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An analysis of previous blackouts in the world: Lessons for China׳s power industry

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Abstract

Large-scale blackouts have occurred frequently throughout the world. The blackouts that have occurred in recent years not only seriously affect the lives of local residents, but they also cause substantial economic losses. In particular, as modern society increasingly depends on electricity, power outages occurring at any time may result in devastating consequences. Accordingly, identifying the reasons for blackouts and implementing proper restoration measures are of particular importance. This paper analyses the sphere of influence, the scale of the effects, the restoration measures and the causes of previous worldwide blackouts. Based on the findings, suggestions for the development of China׳s power industry are then offered.

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... Voltage instability incidents have been identified as contributing factors in several recent worldwide blackouts such as the blackouts occurred in Sweden and Denmark in 2003, the great US Northeast blackout of 2003, the blackout affected the Algerian power system in 2003, the Athens blackout in 2004 and the Brazilian blackout in 2009 [1,2]. ...
... where r 1 and r 2 are random numbers in the range of [ 0,1]; β is a constant (equal to 1.5 in this work) and ζ is given by the following equation. ...
... where a is linearly decremented from 2 to 0 along with the iterations, r is a random vector in [0,1]. Therefore, A is used with the random values |A|>1 in order to guarantee the global search for the WOA algorithm. ...
Thesis
Full-text available
In recent years, due to the economic and environmental issues, modern power systems often operate proximate to the technical restraints enlarging the probable level of voltage instability risks. Hence, fast and efficient methods to assess and enhance power system voltage stability are of great importance to experts and industries in order to avoid a risk of large blackouts. In this thesis, firstly, new hybrid models based on the combination of Support Vector Regression (SVR) with modern meta-heuristic optimization algorithms have been developed and implemented to predict power system Voltage Stability Margin (VSM). As the performance of the SVR model heavily depends on a careful selection of its parameters, the AntLion Optimizer (ALO), Dragonfly Algorithm (DA) and Whale Optimization Algorithm (WOA) are adapted to seek for the SVR‟s optimal parameters, which significantly improve its performance. In order to ensure the suitability of the proposed approach for on-line applications, the input features of the hybrid models are provided in the form of voltage magnitudes and voltage phase angles, measured by Phasor Measurement Units (PMUs). Consequently, the above-mentioned algorithms i.e., ALO, DA and WOA are used to identify the weak buses in a large-scale power system based on the optimal location of reactive power support. Finally, an Event-driven Emergency Demand Response (EEDR) based VSM is proposed for voltage stability improvement. The main objective of the proposed EEDR approach is to maintain VSM in an acceptable range during emergency conditions. Validation process was conducted on two test systems namely the IEEE 14-bus and the Algerian 114-bus which produced promising results.
... where their apparent stability can abruptly change state (Dobson et al., 2007;Viejo et al., 2015). The complex intertwining of unforeseeable coincidences may cause rapidly cascading failure in the power system, and, in the worst case, result in a blackout (Bo et al., 2014) -a wide-area outage of long duration (NAS 2017). A blackout in turn normally results in further cascading failure across other interconnected and interdependent infrastructures, e.g. ...
... Large blackouts are low-probability high-consequence events that often result in significant social and economic impact (Bo et al., 2014). In most developed nations with their highly interconnected grids, a blackout is rapidly restored through interconnections from neighboring areas that still have power (Bo et al., 2014). ...
... Large blackouts are low-probability high-consequence events that often result in significant social and economic impact (Bo et al., 2014). In most developed nations with their highly interconnected grids, a blackout is rapidly restored through interconnections from neighboring areas that still have power (Bo et al., 2014). However, in the case of a national blackout, none of Eskom's neighboring electricity utilities have the capacity to restart the South African power system, which highlights the importance of resilience in general, and a black-start capability in particular. ...
Thesis
Full-text available
Electricity supply serves as a lifeline, is foundational to the effective functioning of modern society, and powers multiple layers of other critical infrastructure systems. In South Africa, Eskom, the national state-owned electrical utility, generates 95% of the country’s electricity, making the South African economy highly dependent on the utility. Eskom has been caught up in socio-political, technical and financial challenges, including corruption and state capture allegations. Futhermore, owing to supply deficits, Eskom had to resort to national load-shedding from 2007 to 2008 and from 2014 to 2015. Withdrawal of labour and acts of sabotage by employees during a national strike again necessitated load-shedding between June and August 2018. Eskom is described as the biggest risk to the South African economy, by investment bank Goldman Sachs in 2017, as well as the International Monetary Fund at the end of 2018. Resilience is a systems-level outcome that emerges as a result of dynamics within complex adaptive systems. An essential service, such as electricity, is resilient if the complex adaptive socio-technical system, from which it is produced, has the capacity to sustain delivery of the core service amidst disruption and ongoing change. A fundamental departure point for this study is the realisation that a resilient technical infrastructure is not enough to ensure the supply of essential services is resilient. The dynamics of the embedded social component is often overlooked, but contributes both inherent strength and vulnerability to the functioning of the socio-technical system that delivers the essential service. This dissertation uses the implications of complexity thinking and resilience thinking to investigate approaches to assess and build the resilience of the embedded social resources required to ensure resilient essential service delivery. The specific objectives of the study were to: develop a conceptual framework for assessing resilience of essential services; pilot two methods for assessing and building resilience (through a principle-based formative assessment approach and a narrative-based sensemaking approach); and to describe the SenseMaker® methodology, as it is increasingly utilized in academic research. These objectives were addressed through four research papers around which the dissertation is structured: The first paper develops a framework to conceptualise domains of resilience that distinguish between social and technical resilience investments, on the one hand, and between specified and general resilience, on the other. Specified resilience deals with resilience of particular system components to defined threats, whereas general resilience is a generic capacity to adapt and transform amidst unpredictable threats and unforeseen risks. Investments in all four of these domains are required in complex adaptive socio-technical systems to ensure resilient essential services. The paper also distinguishes between summative and formative resilience assessments. The first involves assessments of resilience whose primary aim is to report to a third party what is in place. The second entails assessments for resilience whose primary aim is to establish, through engagement with relevant stakeholders, what resilience is required and agree collectively on how to build it. The second paper develops and pilots a formative resilience assessment approach, using an appreciative inquiry facilitation approach to assess how the seven generic resilience building principles from the field of socio-ecological systems can be utilised to enhance general social resilience within socio-technical systems. Six participatory workshops were conducted that produced assessments situated in the collective experiences and perspectives of the participants. The study operationalised the seven resilience building principles into an assessment process that can be rapidly and repeatedly conducted to involve several members of a community. The study found participants identified opportunities to enhance resilience based on the principles of resilience governance towards adaptive and transformative resilience capabilities. The third paper provides a detailed description of the SenseMaker® method used to perform the sensemaking-based resilience assessment in paper four. Originally developed as a decision-making tool for corporate businesses, SenseMaker® is now increasingly used by researchers, but has not been well documented in the academic literature. This paper describes the SenseMaker® method, how it can be used, and its significance and shortcomings in research settings. The fourth paper develops and pilots a narrative-based sensemaking approach for assessing the strength of social resilience competencies and the relative combinations of specified and general social resilience resources that people draw on in the face of disruption. The approach was piloted in a national emergency exercise conducted in Eskom, which simulated sudden cascading failure across interdependent systems and functions. The study found that employees drew more on specified than general resilience resources. Results were interpreted relative to the quality of cognitive, connective and purposive sensemaking that participants displayed in response to the simulated failure. The key contribution of this dissertation is that it provides conceptual clarity regarding the different domains of resilience that need to be considered in socio-technical systems. Moreover, the study develops and pilots two methods for assessing social resilience. The first assessment approach is formative and uses the seven principles; and, the second is summative, using the narrative-based sensemaking approach. The importance of sensemaking capacities in social resilience is emphasized, and methodological clarity on the use of the SenseMaker method in research settings is provided. The findings from this study advance conceptual and methodological aspects of resilience assessments, in particular assessments of the social dimension of socio-technical systems. This study is especially significant as it was performed in a technical organization with an engineering driven culture, but focused on social aspects that affects systems-level resilience. These insights may also have relevance in advancing the assessment of social dimensions of resilience in social-ecological systems. On a practical note, the findings may assist a wide range of actors seeking to assess and build the resilience of essential service delivery in socio-technical systems.
... Elektrik kesintilerinin ortaya çıkmasında, mevsim değişiminden teknik arızaya dahası terör saldırılarına kadar birçok faktör etkili olmaktadır. Bu faktörler genel olarak 3 gruba ayrılabiliriz [4,6,7]: a) Dış ortamdan kaynaklı nedenler: Elektrik kesintileri genel olarak deprem, kasırga, heyelan, tsunami gibi doğal afetlerden veya şiddetli rüzgâr, yoğun yağmur yağışı, yıldırım düşmesi, kar fırtınası, tropikal fırtınalar, aşırı sıcaklık gibi yoğun hava koşullarından kaynaklanabilir. Bu nedenlere ek olarak göz ardı edilse de ciddiye alınması gereken nedenlerden bir tanesi de bitki örtüsünün elektrik sistemleriyle temasa neden olabilecek yakınlığıdır. ...
... Tablo 1. Elektrik kesinti kronolojisi [7] Elektrik kesintilerinin ciddiyeti açısından en önemli kriterler ise etkilenen insan sayısı, kaybedilen yük ve kesintisi süresidir. Araştırmacılar tarafından yapılan çalışmalar ve ilgili kurumların sunmuş olduğu raporlar doğrultusunda bahsi geçen üç kriter bağlı olarak yapılan elektrik kesinti kronolojisi Tablo1'de verilmiştir [6,7,[10][11][12][13]. Bu sınıflandırmaya göre hem etkilenen insan sayısı hem kaybedilen yük hem de kesintisi süresi bakımından bugüne kadar yaşanan dünyadaki en büyük kesinti Hindistan'da olduğu görülmektedir. ...
... Kesintilerin sosyal düzen üzerindeki etkileri de göz ardı edilmeyecek noktadadır. Sosyal düzeni;  Trafik sinyalizasyonundaki bozulmadan kaynaklı trafik tıkanıklığı;  Hızlı tren, metro ve tramvay seferlerinin durması ve yolcuların mahsur kalması,  Uçakların acil iniş yapması ve yapılması planlanan uçak seferlerinin iptal edilmesi,  Sabit ile mobil telefon hatlarının ve internetin servis dışı kalması sonucu iletişimde aksamaların yaşanması,  Kesinti anında madende insanların mahsur kalması veya gerekli yardımın yapılmaması sonucu ölmesi,  Rafineri veya fabrikalarda kazaların yaşanması,  Çatışmaların ve kargaşanın baş göstermesi, gibi durumlar etkilemektedir [6]. Elektrik kesintilerinin yaratacağı en büyük sıkıntılar ise insan hayatını doğrudan etkilediği için hastane ve tıbbi tesislerin çalışmasında yaşanabilecek aksaklıklardır. ...
Article
Full-text available
Günümüzde modern toplum yapısındaki değişimler ve teknolojideki gelişmelerle birlikte elektrik enerjisi vazgeçilmez bir kavram haline gelmiştir. Elektrik enerjisinin hemen hemen her sektörde yaygın bir şekilde kullanılması beraberinde enerjiye olan talebin her geçen gün sürekli olarak artmasına dolayısıyla da enerji talebinin karşılanmasında mevcut güç sistemleri yetersiz kalmasına neden olmaktadır. Bu durumun üstesinden gelebilmek için güç sistemlerine eklenen yeni üretim ve teknoloji birimleri mevcut sistemleri daha karmaşık hale getirmektedir. Dahası enerji talebindeki artışın durdurulamaz olması sistemin maksimum kararlılık sınırında çalışmasına neden olmaktadır. Yaşanılan bu durumlar ise güç sisteminin bazı zorluklarla karşılaşma olasılığını arttırmaktadır. Güç sistemleri için yaşanabilecek en büyük zorluk ise son yıllarda dünyada çok sık meydana gelen elektrik kesintileridir. İnsan yaşamının hem sosyal hem de ekonomik olarak ciddi şekilde etkilenmesine neden olan kesintilerin, neden-sonuçlarıyla iyi bir şekilde analiz edilmesi, gerekli düzenlemelerin yapılarak yaşanabilecek kesintileri ve etkilerini en aza indirgemesini sağlaması açısından son derece önemlidir. Yaptığımız bu çalışmada hem dünyada hem de Türkiye’de meydana gelen elektrik kesintilerinin nedenleri, etki alanları ve alınabilecek önlemler hakkında bilgi verilmiştir. Ayrıca örnek güç sistemi üzerinden kesinti analizleri yapılmıştır.
... Prolonged power failures have been recorded in several countries that were connected to power grids failures and required response interventions to curtail their impacts. For example, between 30 July and 1 August 2012, three large blackouts were recorded in India, which are recognised globally as the world's largest blackouts so far (Zeng et al., 2015). The blackouts, which spread over a wide area, led to extended power outages with huge impacts on India's population. ...
... Considering that blackouts affect the operations of other essential systems, it becomes imperative to improve preparedness by the various organisations involved to respond rapidly when such events occur so that their impacts will be minimal. According to Zeng et al. (2015), blackouts affect society in several ways, such as traffic paralysis; large numbers of people being trapped in subways and roads; the shutting down of electric railway stations; interruptions of communication networks, health systems, water supply systems, and financial and stock markets; and social disorder. Factors including issues related to protection of power grids, inadequate voltage, insufficient remedial actions, inadequate training, poor communication and/or coordination, high transmission utilisation, lack of regulations, inadequate situational awareness, failures in operation procedures, design issues, maintenance errors, insufficient technical upgrades, lack of generation reserves and insufficient maintenance of the power supply system are considered the cause of power failures generally (Veloza and Santamaria, 2016). ...
... Factors including issues related to protection of power grids, inadequate voltage, insufficient remedial actions, inadequate training, poor communication and/or coordination, high transmission utilisation, lack of regulations, inadequate situational awareness, failures in operation procedures, design issues, maintenance errors, insufficient technical upgrades, lack of generation reserves and insufficient maintenance of the power supply system are considered the cause of power failures generally (Veloza and Santamaria, 2016). As society continues to depend on electricity in many ways, interruption of supply can have direct or indirect effect on the stability of social order and economic development (Zeng et al. 2015). As Christopher, et al. (2007) noted, reducing the impacts of blackouts requires electrical safety and protection of electrical infrastructure which can only be possible through adequate planning by developing measures that consider the above actors as a means of improving preparedness. ...
Conference Paper
One response to disaster incidents in Nigeria is to improve institutional preparedness and strengthen the capacity of the organisations involved. This requires adequate resources, improved communication and enhanced operations of the national emergency operations centre (EOC) to intensify coordination and better allocate resources. Factors affecting vulnerability to disasters such as building collapses, stampedes and blackouts, and the capacity of Nigeria’s emergency management organisations (considering resource availability, communication ability and operations of the EOC), were evaluated for the six main organisations involved in emergency response in Nigeria: National Emergency Management Agency, Federal Ministry of Health, Nigeria Police Force, Nigeria Security and Civil Defence Corps, Federal Road Safety Corps and National Hospital. Qualitative and quantitative approaches involving questionnaires and interviews were used. Poor housing and infrastructure, lack of disaster education, socio-economic challenges and institutional failures are the main factors that affect vulnerability to building collapses in Nigeria. Institutional failures, political issues and lack of disaster education affect blackouts, while socio-economic factors, institutional failures, political issues and lack of disaster education predominantly affect vulnerability to stampedes. Despite the need to have available resources, effective communications and functional EOCs, it appears that effective response and the implementation of emergency response activities in Nigeria are hindered by lack of adequate resources, lack of resource-sharing networks between federal, state and local government, lack of accountability, inadequate availability of equipment such as mobile phones and radios, and absence of communication networks such as LAN and WAN. Location and accessibility of each EOC, communication ability within the centre, and resources available to the EOC significantly influence the success or failure of operations of the EOC, which in return affects coordination, cooperation and integration among different levels of government and other organisations involved. In conclusion, there is a need for an emergency management plan that includes all elements and enhances resource availability and utilisation, effective communication, and coordination and allocation of resources to prevent, mitigate and respond rapidly to disasters.
... However, in recent years there have been blackouts that have represented a great impact and relevance, by the number of users affected, and the economic losses. In 2003, a blackout occurred in the US and Canada, causing a power loss of about 62 GW over 2 days, and direct economic losses of about $6.4 billion [6]. In 2012, the combination of three blackouts in India caused the largest recognized one in history, leaving more than 600 million users without service [7]. ...
... It also allows studying how far the system can be kept operable in case of a failure in the lines. The new objective function is presented in (6). ...
... Based on the values of the factors and , the alternative system dispatch solution is calculated by applying the objective function (7) and the constraints (2)(3)(4)(5)(6)(7)(8). The average between the two factors only applies to the lines at risk (L1, L2, L4, L5, and L6). ...
Conference Paper
The operation of electric power systems is a complex task that includes the control and supervision of a great number of elements. A failure in any of them could generate system disturbances and, if they get worse, blackouts can be produced. In this regard, this works presents a model that helps with the decisions in the field of efficiency of these systems. The model analyzes the line status considering the combination of factors that are not frequently addressed in the literature. It allows enhancing the operation decisions by proposing alternative schedules that reduce the possibility of the systems to suffer failures. To prove the effectiveness of the model, a real case is studied: the great blackout of the Argentine System in 2019. Results show alternative solutions, which would have been useful to operate the system during this event, by reducing the power flows in risk lines with only 0.05% of the cost increase.
... In recent years, serious power grid blackouts have occurred throughout the world bringing with them important economic losses and affect the lives of residents. Voltage instability incidents have been identified as contributing factors in several recent worldwide blackouts [1]. Therefore, developing efficient countermeasure techniques for the prevention of voltage collapses has attracted important aspects of power system companies and researchers. ...
... The second one is the spiral updating position. In this approach the distance between the whale located at (X, Y) and the prey located at (X*, Y*) is first calculated (see Fig. 4), then the spiral equation to imitate the helix-shaped movement of humpback whales is formed as follows: Fig. 12 VSI before and after EEDR in the case of loss of line (1)(2) in the IEEE 14-bus system ...
... By computing this voltage stability index, we can estimate the VSM of the system and thereby convenient countermeasure may be taken if the index indicates a poor VSM. In the second step, WOA optimization algorithm is used to solve the problem of determination of suitable locations for load reduction represented by (1). Assuming that all the load buses in the power system can participate in the EEDR program, the procedure used to find the appropriate locations, using WOA algorithm, is summarized in the flowchart of Fig. 6. ...
Article
Full-text available
In recent years, due to the economic and environmental issues, modern power systems often operate proximately to the technical restraints enlarging the probable level of instability risks. Hence, efficient methods for voltage instability prevention are of great importance to power system companies to avoid the risk of large blackouts. In this paper, an event-driven emergency demand response (EEDR) strategy based on whale optimization algorithm (WOA) is proposed to effectively improve system voltage stability. The main objective of the proposed EEDR approach is to maintain voltage stability margin (VSM) in an acceptable range during emergency situations by driving the operating condition of the power system away from the insecure points. The optimal locations and amounts of load reductions have been determined using WOA algorithm. To test the feasibility and the efficiency of the proposed method, simulation studies are carried out on the IEEE 14-bus and real Algerian 114-bus power systems.
... One of the problems that may arise in the case of powering a small loaded island in the initial phase of power system restoration is the occurrence of voltage oscillations in addition to frequency fluctuations. Blackouts occur in different countries around the world and there are many causes for them such as the damage or overloading of transmission lines or other parts of the power system, short-circuits, failure of protection systems, failure of control systems, extreme weather conditions, and others [1][2][3][4][5][6][7]. ...
... (2) is the phase shift between voltage and current with the frequency f 1 (radians), φ 2 is the phase shift between voltage and current with the frequency f 2 (radians), t is the time (seconds). ...
Article
The article discusses the low-frequency oscillations of active power and reactive power recorded during real black-start testing in the power system in Slovakia. The occurrence of these oscillations is analyzed by the theory of calculating RMS values of voltage and current, as well as by measuring the mean value of active and reactive power. The mathematical analysis and theoretical simulations described in this paper confirmed the supposed cause of the measured low-frequency oscillations. These oscillations were caused by inappropriate time window for RMS values as well as active and reactive power evaluation because of two different dominant power frequencies existed. Mutual interconnections between power lines installed on one four-system power line were responsible for the occurrence of these two different dominant frequencies because one line was operated in an island and three other lines were operated in the interconnected grid with frequency 50 Hz. Understanding the cause of low-frequency oscillations occurrence is necessary for the process of finding technical solutions for its elimination.
... The major disadvantage of these oscillations is that they may grow up with time and can lead to severe blackouts. 11,[23][24][25] It means that there is a need for timely control signal to damp out the low-frequency oscillations, delay in which could lead to issues in the stability of the power system. 26 1.2 | Literature review A power system stabilizer (PSS) is the controller that is used to provide the appropriate feedback control signal to the excitation system of alternators employed in a particular power system. ...
... This will profoundly improve the probability of reaching the optimal solution for any complex problem by avoiding the nature of stuck in the local optima. 4 Hence for the robustness in the solution of wolf groups, the breeding parasitism behavior of cuckoos can be adopted through CS. 77,78 Hence, the grey wolf position generated can be upgraded by Lévy flight as given in (24). ...
Article
This paper proposes a novel hybrid technique called enhanced grey wolf optimization‐sine cosine algorithm‐cuckoo search (EGWO‐SCA‐CS) algorithm to improve the electrical power system stability. The proposed method comprises of a popular grey wolf optimization (GWO) in an enhanced and hybrid form. It embraces the well‐balanced exploration and exploitation using the cuckoo search (CS) algorithm and enhanced search capability through the sine cosine algorithm (SCA) to elude the stuck to the local optima. The proposed technique is validated with the 23 benchmark functions and compared with state‐of‐the‐art methods. The benchmark functions consist of unimodal, multimodal function from which the best suitability of the proposed technique can be identified. The robustness analysis also presented with the proposed method through boxplot, and a detailed statistical analysis is performed for a set of 30 individual runs. From the inferences gathered from the benchmark functions, the proposed technique is applied to the stability problem of a power system, which is heavily stressed with the nonlinear variation of the load and thereby operating conditions. The dynamics of power system components have been considered for the mathematical model of a multimachine system, and multiobjective function has been framed in tuning the optimal controller parameters. The effectiveness of the proposed algorithm has been assessed by considering two case studies, namely, (i) the optimal controller parameter tuning, and (ii) the coordination of oscillation damping devices in the power system stability enhancement. In the first case study, the power system stabilizer (PSS) is considered as a controller, and a self‐clearing three‐phase fault is considered as the system uncertainty. In contrast, static synchronous compensator (STATCOM) and PSS are considered as controllers to be coordinated, and perturbation in the system states as uncertainty in the second case study.
... But, in the last two decades have been blackouts with an important impact and significance (due to the amount of users without service, and the financial damages). For instance, a great blackout happened in the US and Canada in 2003, it caused about 62 GW of power losses, with a duration of 2 days, and direct financial injuries of more than USD 6 billion [6]. Even worse, the largest recognized blackout in history occurs in India, during 2012, as a result of the combination of three lower blackouts. ...
... In this case, DC model is selected to keep the linear type of the mathematical model, besides the reduction of the computational effort [13]. This model determines that the flow transported between the input bus and the output buses is represented in (6). Where is the voltage angle in the considered bus (in rad), the line reactance (in Identify applicable funding agency here. ...
... The major disadvantage of these oscillations is that they may grow up with time and can lead to severe blackouts. 11,[23][24][25] It means that there is a need for timely control signal to damp out the low-frequency oscillations, delay in which could lead to issues in the stability of the power system. 26 1.2 | Literature review A power system stabilizer (PSS) is the controller that is used to provide the appropriate feedback control signal to the excitation system of alternators employed in a particular power system. ...
... This will profoundly improve the probability of reaching the optimal solution for any complex problem by avoiding the nature of stuck in the local optima. 4 Hence for the robustness in the solution of wolf groups, the breeding parasitism behavior of cuckoos can be adopted through CS. 77,78 Hence, the grey wolf position generated can be upgraded by Lévy flight as given in (24). ...
Article
Full-text available
The improvement of power system stability by damping oscillations in the system states is presented in this paper. An Antlion optimization (ALO) algorithm is adopted to tune the damping device controller parameters. The ALO algorithm performance is investigated on the benchmark functions, and the same has been compared with the traditional PSO technique. The statistical analysis on the fitness achieved with the considered algorithms has been demonstrated using best, worst, mean, and SD values on the benchmark functions over 30 individual runs. Here power system stabilizer (PSS) and Static synchronous Compensator (STATCOM) are considered as oscillation damping devices in the test power network. The analysis has been carried out in a sample power system network, and the proposed technique is compared with the conventional PSS and particle swarm optimization (PSO). The results obtained from the designed test system recommends the superior performance characteristics of ALO in applying to the practical power system.
... EC is imperative in real-time operation to minimize the impact of large-scale power outages and recover the system frequency [4]. An optimal load dispatch strategy is proposed to respond to the EC signals in heat and power microgrids [5]. ...
... 599 suggests the shed load be considered equivalent to the loss load caused by failure to avoid a region suffering from severe LS and affecting the normal life of residents. It stipulates different penalties for different levels of power grids, in which the penalty function of the municipal power grid is adopted and fitted as (4). ...
Article
A decline in power system inertia challenges the frequency control, especially in a regional receiving-end power system. Conventionally, load shedding (LS) is the principal measure to recover the reduction in frequency. This paper proposes a two-stage frequency emergency control (EC) strategy to coordinate the LS and demand response (DR) techniques for frequency regulation to effectively and economically restore stable operation. The framework is divided into first-stage control (EC-I), second-stage control (EC-II), and coordination between EC-I and EC-II. EC-I deals with the condition when the system frequency markedly falls due to severe contingencies, with the LS approach adopted to alleviate the power-demand imbalance. Such control is devised to restore the system frequency above the set frequency index (fnadir,x) with the lowest cost. EC-II is performed based on EC-I to help the system promptly recover to a stable state. The LS and DR techniques are combined in EC-II to further reduce the control expenditure, and a control method for TCLs is proposed with less communication and computational burden to realize the power reduction. To minimize the overall control expenditure, a coordination process is designed with the coordination between EC-I and EC-II, which is reflected in the determination of the value of fnadir,x, as this parameter considerably influences expenditures in both EC-I and EC-II. The proposed framework is implemented in an IEEE 39-bus system, with simulation results demonstrating the effectiveness and economy of the strategy.
... Eventually, the temperature will exceed the thermal limit of OHL and create excessive thermal stress in lines. In the worst-case scenario, overload may result in power blackouts, which can affect social, economic, industrial, and political activities [82]. A study found that the increasing amounts of current flowing through the lines lead to the temperature rise of conductors, as shown in Fig. 8 [83]. ...
Article
Full-text available
The overhead transmission line system is one of the methods of transmitting electrical energy at a high voltage from one point to another, especially over long distances. The demand for electrical energy is increasing due to the increase in the world population, the evolution of transport technology, and economic expansion, thereby resulting in overloading to the overhead line (OHL) system. In building new infrastructure for transmission lines, several issues need to be addressed. Thus, optimizing existing power by increasing the ampacity of power line is a practical solution to meet energy demand issues. During long-term operation, the temperature of OHL conductors may increase beyond their rated temperature, which is typically 75 °C for conventional conductors such as aluminum-conductor steel-reinforced cable. This condition is defined as thermal stress, which results in lower sag vertical clearance, tensile loss, elongation and creep, and reduced life span of the conductors. This condition must be avoided to ensure that the line is not permanently elongated, which can disrupt the vertical ground clearance, and to expand the conductor’s life. Other factors such as lightning, wildfire, aging, and degradation of the conductor can also cause thermal stress on the conductors and have thermal effects on the conductor’s performance. Therefore, unwanted thermal stress needs to be examined and identified by monitoring the thermal effect and behavior of the lines. This paper presents the state of the art in monitoring technologies that can be used to identify thermal stress on OHL conductors, including the issues and challenges in monitoring. At the end of this paper, a few suggestions are included to address the occurrence and assessment of thermal stress in lines. Ultimately, this work may provide complete information to researchers and maintenance engineers to enable them to make better decisions on condition monitoring, operation, and maintenance of the system.
... The main aim of this work centralizes around the mitigation of inter-area power oscillations motivated by the well-established fact that many catastrophic blackout events with the consequent multibillion-dollar economic losses were due to unstable interarea modes of oscillations [1][2][3][4]. Blackouts usually cause astronomical economic casualties and probably escorted by human fatalities, so they are considered as the most catastrophic event from the power system operational perspective [5]. ...
Conference Paper
Full-text available
Power system oscillations jeopardize the secure operation and the integrity of electrical power systems. The main aim of this work is to mitigate inter-area power oscillations motivated by the fact that many catastrophic worldwide blackouts were due to unstable inter-area oscillations. This study explores dual fuzzy logic controllers to orchestrate a coordinated switching strategy for dual novel dynamic braking resistor models for mitigation of inter-area power oscillations in Kundur's two-area test system. The obtained simulation results establish exhilarating confidence and optimism that the proposed scheme will effectively mitigate inter-area power oscillations in accordance with a wide perturbation spectrum.
... The inherent poor damping associated with the inter-area oscillations leaves open wide probabilities for irrevocable widespread blackouts with the consequent eventual devastating outcomes measured in terms of the huge economic casualties and the possible human fatalities [2,5,6]. Due to the unceasing industry's quest to a deregulated platform transition, and the lack of transmission expansion projects, many transmission links are becoming more prone to be convoying heavier electric power transfers often close to the safe maximum loading limit [2,7,8]. ...
Article
Inter-area oscillations are, by far, the most detrimental to the synchronous integrity of interconnected power systems. This detriment comes from their wide frequency spectrum and the large numbers of the participant generators. The inherent poor damping associated with the inter-area oscillations leaves open wide probabilities for irrevocable widespread blackouts with the consequent eventual devastating outcomes measured in terms of the huge economic casualties and the possible human fatalities. This article explores the influences of the Interval Type-2 fuzzy logic-based strategized dynamic braking interventions of dual brake models, namely Thyristor Controlled Braking Resistors (TCBRs), for neutralizing the jeopardy of negatively damped inter-area power oscillations in Kundur’s two-area test system, using MATLAB™/Simulink environment. The relative inner generator's speed deviation is employed in this work as a control signal to the proposed controller. The effectiveness of the proposed scheme is authenticated by considering four case studies with different severity degrees. By analyzing the performance repercussions due to four disturbances, without the implementation of the proposed scheme, the unstable nature of the system responses is clearly noticed. With the implementation of the proposed scheme, the system oscillatory behavior is stabilized in an appropriate manner. The performed comparative non-linear time-domain simulation results emphasize the great potential of the proposed scheme in mitigation of inter-area power oscillations according to the considered disturbances. The proposed scheme is simple yet effective in treating the inter-area oscillations appropriately under the considered case studies.
... If preventive measures are not taken to counter threats to power plants, devastating consequences may result. One of the most likely and important consequences is the creation of deliberate blackouts in the power grid (Bo et al., 2015;Farmer & Allen, 2006;Rose, Oladosu, & Liao, 2007). In this paper, a Carver matrix is used to assess power plants' vulnerability to threats. ...
Article
This paper examines Iran's power plants as potential targets of enemy groups. It identifies the most plausible targets and suggests preventive strategies to counter the threats. There are different models to assess the threat to potential targets. A commonly used model in various fields is the Carver matrix model, which, due to its comprehensiveness, has been used to assess power plants as targets of enemy action. The Carver model has six main factors, each of which is assigned a certain coefficient. To evaluate Iran's power plants as targets, information on their capacity, location, number, age, and fuel type is collected, as well as information on the various threatening groups based around Iran. Using the information on the power plants and the specified coefficients of the Carver matrix, the Iranian power plants have been evaluated as targets. The results of this study indicate that Iran's largest and most sensitive power plants are highly attractive targets for enemies.
... Security of the grid system is related to the smooth development of the national economy and social stability because accidents in the grid system will seriously affect social production and people's lives. For example, the "8.14" blackout in the USA and Canada in 2003 resulted in a total of 29 h of power outages with a loss of 61.8 GW of electricity and left 50 million people without power supply [29]. The November 4, 2006, large-scale power outages in Europe caused a load loss of 16.72 GW and affected the life of 10 million people [30]. ...
Article
Full-text available
Grid-level large-scale electrical energy storage (GLEES) is an essential approach for balancing the supply–demand of electricity generation, distribution, and usage. Compared with conventional energy storage methods, battery technologies are desirable energy storage devices for GLEES due to their easy modularization, rapid response, flexible installation, and short construction cycles. In general, battery energy storage technologies are expected to meet the requirements of GLEES such as peak shaving and load leveling, voltage and frequency regulation, and emergency response, which are highlighted in this perspective. Furthermore, several types of battery technologies, including lead–acid, nickel–cadmium, nickel–metal hydride, sodium–sulfur, lithium-ion, and flow batteries, are discussed in detail for the application of GLEES. Moreover, some possible developing directions to facilitate efforts in this area are presented to establish a perspective on battery technology, provide a road map for guiding future studies, and promote the commercial application of batteries for GLEES.
... Among the currently imaginable categories of power system oscillations, inter-area oscillations are, by far, the most destructive to the synchronous integrity of the interconnected power systems due to their wide frequency range and the huge numbers of the involved generators besides inherent weak damping associated with the inter-area oscillations which leave open wide possibilities for irrevocable blackouts with the resultant devastating consequences measured in terms of massive economic losses and possible human casualties [2,3]. In fact, many catastrophic blackout events with the consequent multi-billion-dollar economic losses were due to the presence of unstable (i.e. ...
Article
Full-text available
Power system oscillations have been long recognized as a problem of great interest in the electric power industry. The main objective of this work focuses on stabilization of inter-area power oscillations motivated by the fact that many catastrophic blackout events with the consequent multi-billion-dollar economic losses were due to the presence of unstable inter-area modes of oscillations. This study will explore dual fuzzy logic controllers to orchestrate a coordinated switching strategy for dual dynamic braking resistors, as a cost-effective method, for stabilization of inter-area power oscillations in Kundur’s two-area test system. Comparative simulation study via MATLAB/Simulink-based modeling and simulation environment of the test model with and without the suggested stabilization regime will demonstrate its effectiveness in stabilizing inter-area oscillations.
... N-1) contingencies. However, several large blackouts still occurred in the US, Europe, India and Brazil in the last two decades [1]- [3]. It has been well recognized that emergency control is imperative in real-time operation to minimize the occurrence and impact of power outages or wide-spread blackouts. ...
Article
// Source Code: https://github.com/RLGC-Project/RLGC. // Power system emergency control is generally regarded as the last safety net for grid security and resiliency. Existing emergency control schemes are usually designed off-line based on either the conceived "worst" case scenario or a few typical operation scenarios. These schemes are facing significant adaptiveness and robustness issues as increasing uncertainties and variations occur in modern electrical grids. To address these challenges, this paper developed novel adaptive emergency control schemes using deep reinforcement learning (DRL) by leveraging the high-dimensional feature extraction and non-linear generalization capabilities of DRL for complex power systems. Furthermore, an open-source platform named Reinforcement Learning for Grid Control (RLGC) has been designed for the first time to assist the development and benchmarking of DRL algorithms for power system control. Details of the platform and DRL-based emergency control schemes for generator dynamic braking and under-voltage load shedding are presented. Robustness of the developed DRL method to different simulation scenarios, model parameter uncertainty and noise in the observations is investigated. Extensive case studies performed in both the two-area, four-machine system and the IEEE 39-bus system have demonstrated excellent performance and robustness of the proposed schemes.
... A failure in a power grid may result in follow-up failures in the grid and other infrastructures [2]. Bo et al. [3] mapped and summarized 23 major blackouts from 1965 to 2012, representing major failures in power grids. Among the surveyed literature, no additional major blackouts were found, which is partially validated by the list of billion-dollar weather and climate disasters [4] in the US. ...
Article
Full-text available
A structured collection of tools for engineering resilience and a research approach to improve the resilience of a power grid are described in this paper. The collection is organized by a two-dimensional array formed from typologies of power grid components and business processes. These two dimensions provide physical and operational outlooks, respectively, for a power grid. The approach for resilience research is based on building a simulation model of a power grid which utilizes a resilience assessment equation to assess baseline resilience to a hazards’ profile, then iteratively selects a subset of tools from the collection, and introduces these as interventions in the power grid simulation model. Calculating the difference in resilience associated with each subset supports multicriteria decision-making to find the most convenient subset of interventions for a power grid and hazards’ profile. Resilience is an emergent quality of a power grid system, and therefore resilience research and interventions must be system-driven. This paper outlines further research required prior to the practical application of this approach.
... N-1) contingencies. However, several large blackouts still occurred in the U.S., Europe, India and Brazil in the last two decades [1]- [3]. It has been well recognized that emergency control is imperative in real-time operation to minimize the occurrence and impact of power outages or wide-spread blackouts. ...
Preprint
Full-text available
// Source Code: https://github.com/RLGC-Project/RLGC. // Power system emergency control is generally regarded as the last safety net for grid security and resiliency. Existing emergency control schemes are usually designed off-line based on either the conceived "worst" case scenario or a few typical operation scenarios. These schemes are facing significant adaptiveness and robustness issues as increasing uncertainties and variations occur in modern electrical grids. To address these challenges, for the first time, this paper developed novel adaptive emergency control schemes using deep reinforcement learning (DRL), by leveraging the high-dimensional feature extraction and non-linear generalization capabilities of DRL for complex power systems. Furthermore, an open-source platform named RLGC has been designed for the first time to assist the development and benchmarking of DRL algorithms for power system control. Details of the platform and DRL-based emergency control schemes for generator dynamic braking and under-voltage load shedding are presented. Extensive case studies performed in both two-area four-machine system and IEEE 39-Bus system have demonstrated the excellent performance and robustness of the proposed schemes.
... In most cases, system disruptions and failures due to natural disasters, such as thunderstorm and severe lightning events, can interrupt the power supply to the consumers. More recently, the more frequent occurrence of extreme weather conditions due to global warming and the El Niño effect [3,4] have also been identified as factors that reduces the reliability. ...
Article
Full-text available
This article presents alternative analyzing method of extracted dissolved gases related to insulating oil of power transformers. Analysis of soluble and free gas is one of the most commonly used troubleshooting methods for detecting and evaluating equipment damage. Although the analysis of oil-soluble gases is often complex, it should be expertly processed during maintenance operation. The destruction of the transformer oil will produce some hydrocarbon type gases. The development of this index is based on two examples of traditional evaluation algorithms along with fuzzy logic inference engine. Through simulation process, the results of the initial fractures in the transformer are obtained in two ways by the "Duval Triangle method" and "Rogers's ratios". In continue, three digit codes containing the fault information are created based on the fuzzy logic inference engine to achieve better results and eliminate ambiguous zones in commonly used methods, especially in the "Duval Triangle method". The proposed method is applied to 80 real transformers to diagnose the fault by analyzing the dissolved oil based on fuzzy logic. The results illustrate the proficiency of this alternative proposed algorithm. Finally, with utilization of a neural network the alternative practical inference function is derived to make the algorithm more usable in the online condition monitoring of power transformers.
... The economical implications of the post-peak will make power distribution more unstable, and the development and maintenance of big infrastructures much more difficult. Electricity has become a vital part of modern societies, being fundamental in our daily life, as well as in many sectors, such as governmental, commercial and industrial areas [3], [4]. For this reason, energy interruptions paralyse the daily routine, compromising all the services which directly rely on the power supply. ...
... It has been noted that mental health problems such as stress, depression, and anxiety can increase [50,82]. Furthermore, the lack of information and slow emergency response after prolonged power outages may also lead to public discontent, uprisings, looting and crime [13] as observed after certain major disasters, including the 2005 earthquake in Pakistan [2]; the 2005 Hurricane Katrina [23]; the 2010 Haiti earthquake [8]; and the 2010 Chile earthquake and tsunami [70]. Yes, these social impacts have been identified, but there is no evidence concerning the long-term impact. ...
Article
This paper examines the short and long-term societal impact of prolonged power outages caused by a disaster, and the way of coping that the community develops. Community resilience is used as a conceptual framework to analyse the community responses to power outages following the 2010 Chile earthquake. Based on empirical evidence from longitudinal qualitative research we explore the resilience capacities and resources deployed in five low-income communities within Talcahuano, one of the cities most heavily affected by the power outage. Our research reveals that community resilience attenuates the negative consequences of power outages during the response and recovery periods. However, external assistance is required to reduce the short and long-term societal impact of prolonged outages. Policy recommendations and guidelines are provided on how to increase community resilience and reduce the negative impact of long-lasting power outages.
... The main aim of this work centralizes around the mitigation of inter-area power oscillations motivated by the well-established fact that many catastrophic blackout events with the consequent multibillion-dollar economic losses were due to unstable interarea modes of oscillations [1][2][3][4]. Blackouts usually cause astronomical economic casualties and probably escorted by human fatalities, so they are considered as the most catastrophic event from the power system operational perspective [5]. ...
Conference Paper
Power system oscillations jeopardize the secure operation and the integrity of electrical power systems. The main aim of this work is to mitigate inter-area power oscillations motivated by the fact that many catastrophic worldwide blackouts were due to unstable inter-area oscillations. This study explores dual fuzzy logic controllers to orchestrate a coordinated switching strategy for dual novel dynamic braking resistor models for mitigation of inter-area power oscillations in Kundur's two-area test system. The obtained simulation results establish exhilarating confidence and optimism that the proposed scheme will effectively mitigate inter-area power oscillations in accordance with a wide perturbation spectrum.
... Therefore, while enjoying convenience and comfort brought by electricity, protection of the power system against catastrophic accidents has been an unavoidable challenge. In recent years, several blackouts caused by cascading failures have severely affected production and daily life [1][2][3]. Meantime, with tighter electrical coupling within internal power networks, cascading failures can spread rapidly, giving rise to much of the recent research into identification, prediction, and mitigation of cascading failures [4,5]. ...
Article
Full-text available
Abstract Minimizing the risk of cascading failures in a power system is vital to balance the operational economy and security. A multi‐step corrective control (MSCC) method is proposed to mitigate cascading effects in terms of reducing risk of blackout by considering the multi‐step propagation characteristics of cascading failures caused by overload. Based on fault chain model and the DC power flow equation, the dynamic interaction between the process of cascading failures and control schemes is first discussed. The corrective control problem is then expressed as a multi‐step decision‐making optimisation problem based on the defined risk indices. The MSCC model with flexibility of control timing is designed by optimizing probability weighting expected cost and overload risk of cascading failure. In this control method, generation re‐scheduling and load shedding are selected as the main remedial actions, and a multi‐layer coding genetic algorithm is employed to obtain the optimal remedial control schemes. The numerical results indicate that control schemes generated by the proposed method could mitigate the cascading failures and result in better performance than non‐recurring corrective control (NCC) in terms of economy and operational risk.
... Accordingly, it is important to identify the reasons for the outage and to implement appropriate recovery measures. A paper analyses the field of influence, the scale of effects, the recovery measures and the causes of previous interruptions in the world (Bo et al., 2015). In a study using a survey of car owners, structural equations were modeled based on the relationship between service quality and its impact on customer satisfaction and loyalty. ...
Article
Purpose The purpose of this paper is to describe a novel method to compromise between planned (regulated) maintenance and outage initiation and unplanned (unregulated) maintenance and to find an economic model using which one can perform maintenance adequately and in the most optimal state. Design/methodology/approach In this paper, a system consisting of similar components is considered, and the role of each component in the system is explained. Then, the cost pertaining to failure in each asset is determined. Costs such as energy not supplied, penalties, human resources to resolve the defect and replacing assets are taken into account. Finally, a new comprehensive objective is proposed, and optimization is performed for a sample system. Findings In this paper, some graphs have been plotted from which plenty of information may be extracted. This is mentioned in the Conclusion. Originality/value In this paper, some graphs have been plotted from which plenty of information may be extracted. This is mentioned in the Conclusion.
... In most cases, system disruptions and failures due to natural disasters, such as thunderstorm and severe lightning events, can interrupt the power supply to the consumers. More recently, the more frequent occurrence of extreme weather conditions due to global warming and the El Niño effect [3,4] have also been identified as factors that reduces the reliability. ...
Article
Full-text available
A lightning monitoring system is used to observe, collect and analyze lightning activities so that a preventive measure to protect power equipment from severe damage can be planned. A proper system increases sustainability of the electrical energy supply. Regarding to this topic, no comprehensive review papers for evaluation of utilized technologies and their performances, are prepared. Owing to the literature gap, this paper is written to summarize the working principles of the relevant sensors and the various methods of data transmission, storage and analysis the acquisitioned data for localization of strike occurrence. Furthermore, new developed systems and compare of the detection techniques are also presented in this essay. The methods to transmit the required data of lightning signals are also discussed in details.
... As a result of such increased inter-connectivity, outages can propagate across networks spanning multiple scales due to losses in physical connectivity, the failure of a co-located infrastructure, or a disruption to information flow and logical processes (Rinaldi, Peerenboom, and Kelly 2001). Such disruptions can lead to cascading failures with significant societal or economic impactsnotably when initiated from the electricity sector (van Eeten et al. 2011;Kjølle, Utne, and Gjerde 2012;Zeng et al. 2015). In particular, analyses of past events have highlighted the vulnerability of transportation networks (e.g. ...
Article
Critical infrastructure systems are typically managed as isolated systems, however, past events have demonstrated that disruptions to electricity supply can initiate major social and economic impacts on dependent infrastructure. This paper investigates the role of electricity on the functioning of the New Zealand national passenger–transportation sectors, namely: airports, ferries, rail, and petroleum distribution via state highways. Expert-elicited relationships used to define electricity-transport dependencies in practice are compared and updated using a national-scale network-of-networks simulation model – a methodology with the advantage of capturing a far greater range of possible dependency relationships compared to a single expert-elicited curve. Examining the geographic and functional dependence on the electricity transmission/distribution networks, critical substations for normal transportation sector functionality are identified. Through simulating disruptive scenarios, we derive a synthesised set of curves integrating the qualitative and quantitative approaches to characterising infrastructure dependencies. While urban areas show dense co-location of transport assets and critical substations with significant potential for disrupting transportation, the routing of petroleum from bulk storage terminals to retail stations reveal the criticality of road networks beyond simple traffic count metrics. This approach in modelling infrastructure dependencies at the national scale is not without limitations and these are reflected on accordingly.
... Currently, thermal energy storage (TES) is being considered as one of the effective solutions to overcome this challenge. On the other hand, HVAC systems have been identified as the single largest contributor to peak demand on electric grids and are one of the primary causes of grid failure, resulting in blackouts [4,5]. The integration of TES with HVAC systems could mitigate the peak electricity demand of HVAC systems through effective load shifting [6,7]. ...
Article
This paper presents the development, experimental testing, and numerical investigation of water-based phase change material (PCM) thermal energy storage (TES) using the shell-and-tube design with different tube layouts including single serpentine, double serpentine, and spiral. Sodium acetate trihydrate (SAT) with a melting temperature of 58 °C was used as the storage medium. The major contribution of this study is the sensitivity analysis and performance comparison of the shell-and-tube PCM TES units with different tube layouts. A quasi-three-dimensional dynamic model of the PCM TES unit was developed and used to predict the performance of the TES unit under different design and operating conditions, which was validated against the experimental data. A global sensitivity analysis was implemented to quantify the influence of the design parameters on the performance of the PCM TES unit. The results showed that the inlet water temperature was the most influential parameter, followed by the tube length, water flow rate, tube layout, and PCM thermal conductivity. The PCM TES module with the spiral tube layout and the double serpentine tube layout generally outperformed that with the single serpentine tube layout. The time required to charge the PCM to a liquid fraction of 0.95 was reduced by 16.0% if changing the tube layout from single serpentine to spiral and when the tube length was 4,055 mm. The findings obtained from this study could be potentially used to guide and facilitate the design of the shell-and-tube PCM TES units.
... In this study, Sidr affected i.e. south west part in Bangladesh is the study area. Bo et al.(2015)studied devastating consequences of large-scale blackout of electricity. They suggested a continuous improvement of electric power system i.e. risk identification, research and identification of potential improvement are essential for the security of electric power sector. ...
Article
The study was conducted at the Department of Electrical and Electronic Engineering, Begum Rokeya University, Rangpur, Bangladesh during the year 2019. Secondary data were used in this study. Electric power is the basis of human life and plays an important role wherever man lives or works and the electricity requirement of the world is increasing at an alarming rate. So, electric power is essential all over the world including Bangladesh. In this study, security of electric power system in south west cyclone prone areas of Bangladesh is studied. In this regard, loss in electric power system after Sidr, projects under annual program of Ministry of Science and Technology, PGCB as well as government’s ongoing projects and annual allocation in south west part of Bangladesh are taken into account. Beside this, government’s risk mitigation model for disaster is also studied. It has been seen that government is allocating a huge amount of money every year and taking some good initiatives to improve the quality of service and increase the access to electric power all over the country. However, there is no bridging among government, scientific community and electric power system companies to overcome the risk of vulnerability of electric power system infrastructure during disaster specially cyclone. For this reason, a model has been proposed in this study to strengthen the security of electricity supply in south west coastal areas of Bangladesh. This model will not only help electric power company but also allow government of Bangladesh to utilize national think tank properly and lessen the foreign dependency in technical support.
... In cases where people experienced disturbances, these were mainly caused by incidents that were not attributable to individual consumers but were caused by external influences (e.g., strong meteorological effects damaging connection lines and separating areas within the grid). 9 Consequently, this absence of major losses or reductions in service quality can lead to a deceptive feeling of security of supply. 10 Considering this, there has been no need for consumers to understand domain-specific details about the resilient operation of the grid. ...
Article
Full-text available
The transition of energy grids toward future smart grids is challenging in every way: politically, economically, legally, and technically. While many aspects progress at a velocity unthinkable a generation ago, one aspect remained mostly dormant: human electricity consumers. The involvement of consumers thus far can be summarized by two questions: “Should I buy the eco-friendly appliance? Will solar pay off for me?” However, social and psychological aspects of consumers can profoundly contribute to resilient smart grids. This vision paper explores the role of active consumer-producers (prosumers) in the resilient operation of smart energy grids. We investigate how data can empower people to become more involved in energy grid operations, the potential of heightened awareness, mechanisms for incentives, and other tools for enhancing prosumer actions toward resilience. We further explore the potential benefits to people and system when people are active, aware participants in the goals and operation of the system.
... Some parts of the optimization algorithm code itself are given later, for the sake of clarity and a better understanding of the process. Note, many uncertainty modeling techniques in power system studies can be found in the available literature [23]. Among them, we can find a couple of probabilistic methods. ...
Chapter
Distance relay is designed with different overlapping zones to provide complete protection to the associated lines and other lines. From the three different operating zones, the third zone is the delayed operative zone as its operation is followed by the nonresponding operation of the other two zones. However, the operation of zone-3 is not so important but the false operation of the same is a leading factor behind the power system blackout. Maloperation of the zone-3 unit of distance relays during system stressed conditions such as voltage instability, power swing, and load encroachment results in such a disaster. Zone-3 unit of distance relay is heavily affected by such events due to the large reach area and longtime delay. During symmetrical fault in zone-3 section and system stressed events, the impedance trajectory enters into the setting characteristics. So, the relay is unable to make proper discrimination between the different balanced phenomena and operate. As system stressed events are nonfault events, the relay should remain silent. These unwanted consequences lead to cascaded events and further large-area power outage. So, to maintain security, selectivity, proper detection, and discrimination of symmetrical fault from the system stressed events are essential. In this chapter, a complete survey report behind zone-3 maloperation and power system blackout is provided. The main objectives of this chapter are to discuss the impact of uncertainty measures, root causes behind power system blackout, and what are the available solutions to mitigate this issue. The simulation work is conducted in the EMTDC/PSCAD platform to generate the voltage, current, active power, and reactive power signal during system stressed and fault conditions. The IEEE 39-bus test system is considered for the study and to verify the performances of conventional and available techniques.
... The hyperparameters of the DMRL algorithm for the training is shown in Table III. At the training stage, the contingency set {C train } for each environments E trn,i was defined as 18 different contingencies, which was a combination of 2 fault durations (0.05 and 0.08 s) and 9 candidate fault buses (2,3,5,8,12,15,17,23,26). Fig. 6 shows the average rewards with respect to training iterations for both the DMRL and PARS algorithms. ...
Preprint
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As power systems are undergoing a significant transformation with more uncertainties, less inertia and closer to operation limits, there is increasing risk of large outages. Thus, there is an imperative need to enhance grid emergency control to maintain system reliability and security. Towards this end, great progress has been made in developing deep reinforcement learning (DRL) based grid control solutions in recent years. However, existing DRL-based solutions have two main limitations: 1) they cannot handle well with a wide range of grid operation conditions, system parameters, and contingencies ; 2) they generally lack the ability to fast adapt to new grid operation conditions, system parameters, and contingencies, limiting their applicability for real-world applications. In this paper, we mitigate these limitations by developing a novel deep meta-reinforcement learning (DMRL) algorithm. The DMRL combines the meta strategy optimization together with DRL, and trains policies modulated by a latent space that can quickly adapt to new scenarios. We test the developed DMRL algorithm on IEEE 300-bus system. We demonstrate fast adaptation of the meta-trained DRL polices with latent variables to new scenarios including unseen power flow cases, new system dynamic parameters, and new contingencies using the proposed method and achieve superior performance compared to the state-of-the-art DRL method and model predictive control (MPC).
Article
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The large-scale interconnection of the power grid has brought great benefits to social development, but simultaneously, the frequency of large-scale fault accidents caused by extreme weather is also rocketing. The power grid is regarded as a representative complex network in this paper to analyze its functional vulnerability. First, the actual power grid topology is modeled on the basis of the complex network theory, which is transformed into a directed-weighted topology model after introducing the node voltage together with line reactance. Then, the algorithm of weighted reactance betweenness is proposed by analyzing the characteristic parameters of the power grid topology model. The product of unit reliability and topology model’s characteristic parameters under extreme weather is used as the index to measure the functional vulnerability of the power grid, which considers the extreme weather of freezing and gale and quantifies the functional vulnerability of lines under wind load, ice load, and their synergistic effects. Finally, a simulation using the IEEE-30 node system is implemented. The result shows that the proposed method can effectively measure the short-term vulnerability of power grid units under extreme weather. Meanwhile, the example analysis verifies the different effects of normal and extreme weather on the power grid and identifies the nodes and lines with high vulnerability under extreme weather, which provides theoretical support for preventing and reducing the impact of extreme weather on the power grid.
Thesis
Our societies are more dependent on electricity than ever, thus any disturbance in the power transmission and delivery has major economic and social impact. The reliability and security of power systems are then crucial to keep, for power system operators, in addition to minimizing the system operating cost. Moreover, transmission systems are interconnected to decrease the cost of operation and improve the system security. One of the main challenges for transmission system operators is therefore to coordinate with interconnected power systems, which raises scalability, interoperability and privacy issues. Hence, this thesis is concerned with how TSOs can operate their networks in a decentralized way but coordinating their operation with other neighboring TSOs to find a cost-effective scheduling that is globally secure.The main focus of this thesis is the security of power systems, this is why the evolution of the main characteristics of the blackouts that are failures in power system security, of the period 2005-2016 is studied. The approach consists in determining what the major characteristics of the incidents of the past 10 years are, to identify what should be taken into account to mitigate the risk of incidents. The evolution have been studied and compared with the characteristics of the blackouts before 2005. The study focuses on the pre-conditions that led to those blackouts and on the cascades, and especially the role of the cascade speed. Some important features are extracted and later integrated in our work.An algorithm that solve the preventive Security Constrained Optimal Power Flow (SCOPF) problem in a fully distributed manner, is thus developed. The preventive SCOPF problem consists in adding constraints that ensure that, after the loss of any major device of the system, the new steady-state reached, as a result of the primary frequency control, does not violate any constraint. The developed algorithm uses a fine-grained decomposition and is implemented under the multi-agent system paradigm based on two categories of agents: devices and buses. The agents are coordinated with the Alternating Direction method of multipliers in conjunction with a consensus problem. This decomposition provides the autonomy and privacy to the different actors of the system and the fine-grained decomposition allows to take the most of the decomposition and provides a good scalability regarding the size of the problem. This algorithm also have the advantage of being robust to any disturbance of the system, including the separation of the system into regions.Then, to account for the uncertainty of production brought by wind farms forecast error, a two-step distributed approach is developed to solve the Chance-Constrained Optimal Power Flow problem, in a fully distributed manner. The wind farms forecast errors are modeled by independent Gaussian distributions and the mismatches with the initials are assumed to be compensated by the primary frequency response of generators. The first step of this algorithm aims at determining the sensitivity factors of the system, needed to formulate the problem. The results of this first step are inputs of the second step that is the CCOPF. An extension of this formulation provides more flexibility to the problem and consists in including the possibility to curtail the wind farms. This algorithm relies on the same fine-grained decomposition where the agents are again coordinated by the ADMM and a consensus problem. In conclusion, this two-step algorithm ensures the privacy and autonomy of the different system actors and it is de facto parallel and adapted to high performance platforms.
Article
The increasing integration of renewable energy sources (RESs) into the power system, rapid load changes, and increasing power demand create problems for the stability of power systems. Therefore, the voltage stability index (VSI) becomes an important indicator of power system stability. This paper provides a comprehensive overview of most VSIs and a wealth of resources for researchers, students, and employers. For each VSI, list data such as name, abbreviation, calculation method, assumptions, the basic concept, steady-state, threshold, instability, pros, and cons are discussed in detail. Also, the paper describes the relationship between RESs, load changes, and VSI, and it investigates the stability issues of the power system. The significant outcome of this comprehensive review is to provide a good foundation for future work in this field and helps professionals to choose the best VSI that meets their needs for various applications.
Article
Objective Online estimation of voltage stability margin (VSM) is critical to the long‐term safety and stable operation of power system. In this paper, a deep neural network (DNN)‐based model that incorporates the intrinsic grid topology information is proposed to achieve accurate VSM estimation. Methods The node embedding information together with the electrical parameter measurements are combined together into an array of local structures as the input feature vector. A local‐global deep neural network (LGDNN) model is proposed to extract and integrate the local information into high‐level global representation for VSM estimation. The Node2vec algorithm is employed to obtain embedded node vectors and a NodeRank algorithm is designed to form local structures, which are composed of the measurements of a fixed number of similar nodes according to the similarity among their embedded vectors. A sequential DNN with cascade‐connected depthwise separable 1D convolutional layer and fully connected layer is trained to estimate the current VSM. Results The model performance is validated on the IEEE‐39 and IEEE‐118 benchmark systems under normal and post‐contingency situations. Experiment results indicate that the proposed model can achieve VSM estimation with high precision that surpasses seven mainstream approaches in multiple estimation error indices. Conclusion Through the integration of local structures, the proposed LGDNN increases the estimation accuracy with relatively few parameters than various DNN‐based models. Thus, it is an practical model for online power grid voltage stability monitoring.
Preprint
New Zealand's critical infrastructures are typically managed as isolated systems. Past events have demonstrated that disruptions to electricity supply, for example, can cause major social and economic impacts across electricity dependent infrastructures. This paper investigates and contributes and furthers understanding of the role electricity has on the functioning of the wider New Zealand passenger-transportation sector, namely; airports, ferries, rail, and the petroleum distribution network via state highways. Previous studies have defined system-level dependency relationships of transportation networks on electricity supply through expert-elicitation. Although these are already widely applied in practice, the contribution of this paper lies in the comparison and integration of expert defined relationships with a technical national scale network-of-networks simulation approach -- a methodology with the advantage of capturing a far greater range of possible dependency relationships compared to a single expert-elicited curve. In doing so, we examine the geographic and functional dependencies on different levels of the electricity transmission and distribution networks, identify the critical electricity assets for the wider transportation sector functionality, and through further exhaustive disruption, derive a synthesised set of curves integrating the qualitative and quantitative approaches to characterising infrastructure dependencies. The methodological approach and insights developed here are relevant to similar contexts globally.
Chapter
The expansion of electric power systems and increasing energy demand leads to operating close stability margins and an increase in the risk of voltage collapse. In such a situation, a fast and accurate assessment of voltage stability is necessary to prevent large-scale blackouts. Machine learning techniques are widely applied in the voltage stability assessment according to their ability to train offline and predict results online. This paper presents a novel machine learning framework employed in the online voltage stability assessment. The framework consists of four main stages: database generation, training model, performance evaluation, and online application. For the determined operating conditions, the database is constructed using random sampling based on the continuation power flow. Randomly generated samples are labeled as “secure” or “insecure” using the WECC voltage security criteria. Various machine learning methods are trained using several training sets that are obtained by applying importance sampling and dimensionality reduction. Also, hyperparameters tuning is employed to obtain the best performance; subsequently, the performance is evaluated using different measures such as accuracy and the CPU time. The framework robustness is demonstrated by adding noisy and missing data to the dataset. The proposed framework was tested on the IEEE 39-bus and IEEE 118-bus test. The results confirm the applicability of the proposed framework in the online voltage stability assessment.
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Controlled islanding can enhance power grid resilience and help mitigate the effect of emerging failure by splitting the grid into islands that can be rapidly and independently recovered and managed. In practice, controlled islanding is challenging and requires vulnerability assessment and uncertainty quantification. In this work, we investigate robustness drops due to − line failures and a controlled partitioning strategy for mitigating their consequences. A spectral clustering algorithm is employed to decompose the adjacency matrix of the damaged network and identify optimal network partitions. The adjacency matrix summarizes the power system topology, and different dynamic and static electrical factors such as line impedance and flows are employed to weigh the importance of the grid's cables. Differently from other works, we propose a statistical correlation analysis between vulnerability metrics and goodness of cluster scores. We investigate expected trends in the scores for randomized contingencies of increasing orders and examine their variability for random outages of a given size. We observed that the spectral radius and natural connectivity vary less on randomized failure events of a given size and are more sensitive to the selection of the adjacency matrix weights. Vulnerability scores based on the algebraic connectivity have a higher coefficient of variation for a given damage size and are less dependent on the specific dynamic and static electrical weighting factors. We show a few consistent patterns in the correlations between the scores for the vulnerability of the grid and the optimal clusters. The strength and sign of the correlation coefficients depend on the different electrical factors weighting the transmission lines and the grid-specific topology.
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In this paper, a reintegration-based multi-objective intentional controlled islanding (ICI) model is proposed to enhance resiliency of electrical power systems under catastrophic events. This remedial measure plan relies on a mixed-integer linear programming model with two objective functions including reintegration risk and total load shedding value. While ensuring that each island includes only coherent generators, the proposed multi-objective model solves the controlled islanding problem using lexicographic optimization approach. To ease the islands’ reintegration, charging reactive power, reliability, capacity, and power flow disruption of transmission lines are considered in the model. After implementation of controlled islanding, each resulted island may face temporary active/reactive load-generation imbalance, which may put the islands at the risk of frequency instability, transient voltage instability or a combination of both. The proposed model reduces these risks by modeling energy storage systems (ESSs) and static VAR compensators (SVCs) as fast corrective control actions. In addition to modeling voltage dependent loads in the controlled islanding problem, a linear island frequency response (IFR) model is proposed for frequency stability assessment. The test results of the proposed ICI model on the IEEE 39-bus and IEEE 118-bus test systems demonstrate its performance.
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Electric power systems have become larger, more complex and found to be operating close to their stability limits with small security margin. In such situation, fast and accurate assessment of voltage stability is necessary in order to prevent large-scale blackouts. Due to its ability to learn off-line and produce accurate results on-line, machine learning (ML) techniques i.e., artificial neural networks, decision trees, support vector machines, fuzzy logic and adaptive neuro-fuzzy inference system are widely applied for on-line voltage stability assessment. This paper focuses on providing a clear review of the latest ML techniques employed in on-line voltage stability assessment. For each technique, a brief description is first presented and then a detailed review of the finding published research papers discussed the application of this technique in on-line voltage stability assessment is presented. Based on the conducted review, some discussions and limitations of ML techniques are finally presented.
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Many arising factors endanger the secure and stable operation of transmission grids. Those are deregulation that opens transmission grid, increasing dynamics in consequence of wide integration of variable renewable energy sources, unwillingness to install new transmission lines, electric power demand increase, resulting stress that causes frequent components outage, uneven distribution of power in transmission lines, and resulting low utilization of existing transmission grid infrastructure. In consequence, the need to widely use transmission grid power flow controllers is escalating. However, these power flow controllers need to be reasonably costing as well as technically competent. Three main families of existing power flow controllers are conventional power flow controllers, flexible AC transmission systems controllers, and hybrid power flow controllers, which all have their pros and cons. Conventional power flow controllers are cost-effective, however, have technical shortcomings. Flexible AC transmission systems controllers are technically competent but their cost is high. Hybrid power flow controllers combine some advantages of the other two families, however, have their own limitations, and their cost is still high. Combination of most technical advantages of existing power flow controllers in a single power flow controller at a reasonable cost is promising. Based on a comprehensive review, a family of power transistor- assisted Sen Transformers that bridges the gap between unified power flow controller and Sen Transformer is proposed. Power transistor-assisted Sen Transformers are designed and their comprehensive Simulink model is developed and tested in MATLAB/SIMULINK. Ratings of components of a power transistor- assisted Sen Transformer are determined and its cost is analyzed and compared to that of a similar unified power flow controller. Operation principle of power transistor-assisted Sen Transformers, operational characteristics, and control strategies are revealed. Also, a simplified Simulink model and a comprehensive Newton-Raphson model of power transistor-assisted Sen Transformers are developed and validated. Performance of power transistor-assisted Sen Transformers for enhancement of optimal power flow and also for maintaining grid security is assessed and compared to that of Sen Transformer and unified power flow controller. Methods used include simulation using MATLAB/SIMULINK, analytical Newton- Raphson based load flow analysis, optimal power flow, and simple power flow equations, besides voltage vector analysis. Among the significant findings, operational characteristics of power transistor-assisted Sen Transformers are found closely comparable to those of the unified power flow controller. Power transistor- assisted Sen Transformers operate continuously and provide repeatable control action, error-free, and ensure precise control action. They have non-limited operating points within their control area and ensures increased flexibility, improved response- rate that enables mitigating transient stability problems, extended control range, and far lower cost as compared to an analogous unified power flow controller. As compared to an analogous conventional Sen Transformer, performance of power transistor-assisted Sen Transformer in enhancement of optimal power flow is found to be techno-economically feasible. Also, as compared to an analogous unified power flow controller, power transistor-assisted Sen Transformer is able to maintain grid security and found closely similar with a far lower installation cost. In conclusion, power transistor-assisted Sen Transformers are timely proposed competent and cost-effective power flow controllers those provide tremendous technical and economic benefits to the current days' and the future's smart grids.
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This paper mainly describes the various causes of power system blackouts all over the world which may be the result of one or more than one factors The failure of the power system triggers from various factors such as natural calamities, human factors, electrical malfunctions but one of the root causes for several international power system blackouts have been power mismatch between power generation and demand, thus it is important to analyze the various international events of power system failure as they constitute a real threat not only to electrical power system, but also to safety. The purpose of power grid is to continue supplying power to meet the demand. With increasing electrical energy demand in every industry including the medical world it is very important to maintain power system reliability and stability of the power grid. On failure of automated systems to recognize massive surplus power drawn by a line, the overloaded grid may collapse resulting to additional overhauling of other alternators and thus finally resulting to grid collapse. In this paper various international events of power system blackouts along with their causes have been illustrated. Keywords-Causes of grid failure, various causes of electrical power system blackouts, voltage collapse, frequency collapse, international events of grid failure, comparative study on various international grid
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On Sept. 8, 2011, a large-scale blackout occurred in South America and North Mexico interconnected power gird. General situation and the process of the blackout as well as its harmful effects are presented. The structure of the power grid where the fault occurred and the features of its operation and dispatching are analyzed, and the main causes leading to the blackout, such as heavy load of power grid due to hot weather, weak structure of power grid, non-uniform power grid security management under joint dispatching mode and weak supervision and monitoring ability of grid dispatching centre, are dissected. On the basis on analyzing the large-scale blackout and considering actual situation of dispatching and administration of power grids in China, the lessons from the large-scale blackout for power grid dispatching and administration in China are summarized.
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The objective of this paper is to contribute to the topic of energy supply security by proposing a Monte Carlo-based and a survey based model to analyze the costs of power interruptions. Outage cost estimations are particularly important when deciding on investments to improve supply security (e.g. additional transmission lines) in order to compare costs to benefits. But also other policy decisions on measures that have direct or indirect consequences for the supply security (e.g. a phasing out of nuclear energy) need to be based on results from outage cost estimations. The main focus of this paper lies with residential consumers, but the model is applied to commercial, industrial and governmental consumers as well. There are limited studies that have approached the problem of evaluating outage cost. When comparing the results of these studies, they often display a high degree of diversification. As consumers have different needs and dependencies towards the supply of electricity because of varying circumstances and preferences, a great diversity in outage cost is a logical consequence. To take the high degree of uncertainties into account, a Monte Carlo simulation was conducted in this study for the case of private households in Germany.
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The recent development of small scale combined heat and power (CHP) systems has provided the opportunity for in-house power backup of residential-scale photovoltaic (PV) arrays. This paper investigates the potential of deploying a distributed network of PV CHP hybrid systems in order increase the PV penetration level in the U.S. The temporal distribution of solar flux, electrical and heating requirements for representative U.S. single family residences were analyzed and the results clearly show that hybridizing CHP with PV can enable additional PV deployment above what is possible with a conventional centralized electric generation system. The technical evolution of such PV CHP hybrid systems was developed from the present (near market) technology through four generations, which enable high utilization rates of both PV-generated electricity and CHP-generated heat. A method to determine the maximum percent of PV-generated electricity on the grid without energy storage was derived and applied to an example area. The results show that a PV CHP hybrid system not only has the potential to radically reduce energy waste in the status quo electrical and heating systems, but it also enables the share of solar PV to be expanded by about a factor of five.
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Large-scale blackouts are an intrinsic drawback of electric power transmission grids. Here we analyze the structural vulnerability of the Italian GRTN power grid by using a model for cascading failures recently proposed in Crucitti et al. (Phys. Rev. E 69 (2004)).
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Demand managers currently draw on a limited range of psychology and economic theories in order to shift and shed peak electricity demand. These theories place individual consumers and their attitudes, behaviours and choices at the centre of the problem. This paper reframes the issue of peak electricity demand using theories of social practices, contending that the ‘problem’ is one of transforming, technologically-mediated social practices. It reflects on how this body of theory repositions and refocuses the roles and practices of professions charged with the responsibility and agency for affecting and managing energy demand. The paper identifies three areas where demand managers could refocus their attention: (i) enabling co-management relationships with consumers; (ii) working beyond their siloed roles with a broader range of human and non-human actors; and (iii) promoting new practice ‘needs’ and expectations. It concludes by critically reflecting on the limited agency attributed to ‘change agents’ such as demand managers in dominant understandings of change. Instead, the paper proposes the need to identify and establish a new group of change agents who are actively but often unwittingly involved in reconfiguring the elements of problematic peaky practices.
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An adaptive optimal excitation controller (AOEC) is described. The generator and the power grid connected are identified as an object controlled with recursive least square technique. Then the parameters identified are provided to a special 3 order discrete Riccati equation which is solved in real time to get optimal gain matrix. In theory the adaptive controller has optimal performance under any condition. Dynamic simulations were carried out on a physical model of a single machine infinite bus system to verify the effectiveness of the AOEC. The controller has operated in Gezhouba hydropower plant for 1 year. The experiments on-site also show that the AOEC has good performance
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This study surveys the power failure that affected the Taiwan electrical network on July 29, 1999 (729 blackout). The failure left approximately 82.5% of consumers without power. The first part of the investigation describes the general system characteristics and the condition of the network before the incident. Meanwhile, the second part describes the events during and after the failure. The third part then summarizes the lessons learned from the power blackout. Finally, the last part presents conclusions.
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In the past 20 years, China's economy has grown rapidly, but so has the country's power industry. This paper provides a comprehensive introduction on the current status and the future development of the power transmission systems and grids, which include HVAC and HVDC transmissions, regional power grids and grid interconnections, several important operational issues, e.g., stability problems that China's power grids face, new technologies for increasing transmission capacity, and stabilizing the grids, and so on. Under the constructed UHVAC and UHVDC, some pilot projects and planned future development of UHVAC and UHVDC transmission systems are also introduced.
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In a polarization-division multiplexing soliton system, the multiple soliton interactions are studied numerically, the effects of soliton interactions on timing jitter are analyzed, and a countermeasure using nonlinear gain to suppress the soliton interactions is developed with the help of computer modeling. It is found that the mutual interactions between neighboring solitons cause soliton transmission instability and lead to timing jitter. The interactions of more than two solitons are stronger than that of two solitons. Therefore, the maximum transmission distance limited by the soliton interactions should be inferred from the collision distance of multiple soliton interactions, not the mutual interactions of two solitons. Nonlinear gain combined with a filter is suggested to effectively suppress the soliton interactions and stabilize soliton propagation.
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With the expansion of China's power system, there are more and more factors contributing to Large-area Power Outages. The snow disaster that hit Southern China in 2008 caused serious damages to the power systems, which made Chinese government realize that they cannot solely depend on power enterprises to effectively control the risk involved in power system. The Chinese government needs to collaborate with power enterprises in strengthening Electricity Regulation and taking countermeasures to reduce the risk of Large-area Power Outages. This paper first proposes an objective, practical and adaptive Electrical Security Risk Assessment System based on Electricity Regulation. The system consists of an assessment process with 278 indices, which are used to calculate the risk of Large-area Power Outages by the use of Analytic Hierarchy Process and the Delphi Method. Then, an example of Guangdong power system serves to illustrate the detailed implementation procedures of the proposed assessment system and the results show that Guangdong power system faces a moderate risk of Large-area Power Outages. Finally, some countermeasures are proposed to overcome the defects in the existing power system.
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Increased interconnection has been highlighted as potentially facilitating the integration of wind generation in power systems by increasing the flexibility to balance the variable wind output. This paper utilizes a stochastic unit commitment model to simulate the impacts of increased interconnection for the island of Ireland with large penetrations of wind generation. The results suggest that increased interconnection should reduce average prices in Ireland, and the variability of those prices. The simulations also suggest that while increased interconnection may reduce carbon dioxide emissions in Ireland, Great Britain would experience an increase in emissions, resulting in total emissions remaining almost unchanged. The studies suggest that increased interconnection would not reduce excess wind generation. This is because under unit commitment techniques which incorporate wind power forecasts in the scheduling decisions, wind curtailment is minimal even with low levels of interconnection. As would be expected an increase in interconnection should improve system adequacy considerably with a significant reduction in the number of hours when the load and reserve constraints are not met.
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Traditional electric power systems are designed in large part to utilize large baseload power plants, with limited ability to rapidly ramp output or reduce output below a certain level. The increase in demand variability created by intermittent sources such as photovoltaic (PV) presents new challenges to increase system flexibility. This paper aims to investigate and emphasize the importance of the grid-connected PV system regarding the intermittent nature of renewable generation, and the characterization of PV generation with regard to grid code compliance. The investigation was conducted to critically review the literature on expected potential problems associated with high penetration levels and islanding prevention methods of grid tied PV. According to the survey, PV grid connection inverters have fairly good performance. They have high conversion efficiency and power factor exceeding 90% for wide operating range, while maintaining current harmonics THD less than 5%. Numerous large-scale projects are currently being commissioned, with more planned for the near future. Prices of both PV and balance of system components (BOS) are decreasing which will lead to further increase in use. The technical requirements from the utility power system side need to be satisfied to ensure the safety of the PV installer and the reliability of the utility grid. Identifying the technical requirements for grid interconnection and solving the interconnect problems such as islanding detection, harmonic distortion requirements and electromagnetic interference are therefore very important issues for widespread application of PV systems. The control circuit also provides sufficient control and protection functions like maximum power tracking, inverter current control and power factor control. Reliability, life span and maintenance needs should be certified through the long-term operation of PV system. Further reduction of cost, size and weight is required for more utilization of PV systems. Using PV inverters with a variable power factor at high penetration levels may increase the number of balanced conditions and subsequently increase the probability of islanding. It is strongly recommended that PV inverters should be operated at unity power factor.
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The “European Blackout” of 4 November 2006 is a key reference in current debates on transnational electricity infrastructure vulnerability and governance. Several commentators have observed that to understand what happened, one must look at history. Our paper answers this call and demonstrates how historical choices, path dependencies, and ways of dealing with these afterwards, have shaped Europe's electric power infrastructure and its vulnerability geography. We show that the decentralized organization of transnational electricity infrastructure and governance, often blamed for present-day power grid fragility, was informed by reliability considerations that still count today. We also address the (meso)regional logic of the failure, foregrounding how stakeholders from different parts of Europe historically chose to collaborate in different ways, with due consequences for the 2006 disturbance and other recent blackouts. Finally, the paper observes that today's notion of transnational electricity infrastructure vulnerability, supposedly demonstrated by the 2006 blackout, is highly contested as many stakeholders find the system extremely reliable.
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We analyze and evaluate the evolution of the deregulated market for electricity in Colombia in the period from 1995, when deregulation took place, to 2002. The case of Colombia is of particular interest as it is one of the most open markets in the developing world as well as being predominantly based on hydroelectrical technology. Furthermore, Colombia has had no blackouts since deregulation, in contrast to a number of neighboring countries, even though Colombia has had periods with severe adverse weather conditions. Colombia has so far managed to adjust the regulatory environment to keep investment at a reasonable level. Finally, we discuss the prospects for the Colombian system over the next 5 years.
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This paper describes the development of China's power industry, present situation, environmental influences and potential benefits of regional power grid interconnections in China. Power plants in China are mainly thermal, burning fossil fuels especially coal which emit a great deal of pollutants and greenhouse gases such as SO2, NOx and CO2. China leads all other countries in emissions of SO2, CO2, and the power industry is the largest contributor to these emissions. There are a number of environmental benefits through regional power grid interconnection. That is, the construction of small electricity generation capacity would be avoided; natural resources would be used to generate electricity on a regional scale; and generating sources can be separated from centers of electricity use, which will decrease emission of pollutants and greenhouse gases and help to reduce human exposure to elevated air pollutant concentrations. Therefore, gradually enlarged power grids, and power grid interconnection, should be part of the general pattern of power system development in China.
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We consider optimization problems related to the prevention of large-scale cascading blackouts in power transmission networks subject to multiple scenarios of externally caused damage. We present computation with networks with up to 600 nodes and 827 edges, and many thousands of damage scenarios.
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Communication/transportation systems are often subjected to failures and attacks. Here we represent such systems as networks and we study their ability to resist failures (attacks) simulated as the breakdown of a group of nodes of the network chosen at random (chosen accordingly to degree or load). We consider and compare the results for two different network topologies: the Erdös–Rényi random graph and the Barabási–Albert scale-free network. We also discuss briefly a dynamical model recently proposed to take into account the dynamical redistribution of loads after the initial damage of a single node of the network.
Article
In spite of regional closeness, energy cooperation in Northeast Asia has remained unexplored. However, this situation appears to be changing. The government of South Korea seems to be very enthusiastic for power grid interconnection between the Russian Far East and South Korea to overcome difficulties in finding new sites for building power facilities to meet its need for increased electricity supplies. This paper analyzes the feasibility of this electric power grid interconnection route. The issues addressed include electricity market structures; the prospects for electric power industry restructuring in the Russian Federation and South Korea; the political issues related to North Korea; the challenges for the governments involved and the obstacles anticipated in moving this project forward; project financing and the roles and concerns from multilateral and regional banks; and institutional framework for energy cooperation. While there are many technical issues that need to be resolved, we think that the great challenge lies in the financing of this commercial project. Thus, the governments of the Russian Federation and South Korea involved in the project need to foster the development of their internal capital markets and to create confidence with international investors. To this end, on energy side, this involves defining a clear energy policy implemented by independent regulators, speeding up the already started but delayed reform process of restructuring electric power industry and markets, and establishing a fair and transparent dispute resolution mechanism in order to reduce non-commercial risks to a minimum. The paper argues that establishing a framework for energy cooperation in this region will contribute positively towards that end, although views differ regarding its specific form. Finally, given that North Korea has a crucial transit role to play and faces a very unstable political situation, it is concluded that moving the project forward needs to be contingent on a resolution of the North Korea's nuclear crisis.
Article
This study analyzes the effects of additional interconnection on welfare and competition in the Irish electricity market. I simulate the wholesale electricity markets of the island of Ireland and Great Britain for 2005. I find that in order for the two markets to be integrated in 2005, additional interconnection would have to be large. The amount of interconnection decreases for high costs of carbon, since this causes the markets to become more similar. This suggests that in the absence of strategic behavior of firms, most of the gains from trade derive not from differences in size between countries, but from technology differences and are strongly influenced by fuel and carbon costs. Social welfare increases with interconnection, although at a decreasing rate. As the amount of interconnection increases, there are also positive effects on competition in Ireland, the less competitive of the two markets. Finally, it is unlikely that private investors will pay for the optimal amount of interconnection since their returns are significantly smaller than the total social benefit of interconnection.
Article
Using data from the North American Electric Reliability Council (NERC) for 1984-2006, we find several trends. We find that the frequency of large blackouts in the United States has not decreased over time, that there is a statistically significant increase in blackout frequency during peak hours of the day and during late summer and mid-winter months (although non-storm-related risk is nearly constant through the year) and that there is strong statistical support for the previously observed power-law statistical relationship between blackout size and frequency. We do not find that blackout sizes and blackout durations are significantly correlated. These trends hold even after controlling for increasing demand and population and after eliminating small events, for which the data may be skewed by spotty reporting. Trends in blackout occurrences, such as those observed in the North American data, have important implications for those who make investment and policy decisions in the electricity industry. We provide a number of examples that illustrate how these trends can inform benefit-cost analysis calculations. Also, following procedures used in natural disaster planning we use the observed statistical trends to calculate the size of the 100-year blackout, which for North America is 186,000Â MW.
Article
The idea that increasing the capacity of the transmission network should improve the security of the system and reduce the probability of blackouts is intuitively appealing. However, this intuition does not withstand scrutiny.
Article
Regulators, system operators, and consumers should consider just how much reliability is enough. A widespread blackout that affects 50 million people should never occur with properly designed systems and operating procedures in place. Yet local outages are bound to occur.
Article
Deficiency of human glycerate kinase leads to D-glycerate acidemia/D-glyceric aciduria. Through PCR cloning assisted by in silico approach, we isolated the human glycerate kinase genes--Glycerate Kinase 1 (GLYCTK1) and its alternatively splicing variant--Glycerate Kinase 2 (GLYCTK2), which might be associated with D-glycerate acidemia/D-glyceric aciduria. The locus of GLYCTK gene is mapped to 3p21. PCR amplification in seventeen human tissue cDNAs revealed that both GLYCTK1 and GLYCTK2 are expressed widely almost in all these tissues. The expression of mouse Glyctk in various tissues was demonstrated by in situ hybridization. Both GLYCTK1 and GLYCTK2 proteins are localized in cytosol, and GLYCTK2 proteins are specifically localized in mitochondria. Present results revealed the characteristic expression pattern of murine Glyctk in neural system, skeleton muscle, supporting that glycerate kinase is implicated in D-glycerate acidemia/D-glyceric aciduria.
Development and prospect of China power grids
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Zhao Zunlian. Development and prospect of China power grids. Electricity 2004;15(1):6–11.
Summary of construction for 750 kV transmission pilot project in SG Cop. of China
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Yu Xinqiang, Liang Xuming. Summary of construction for 750 kV transmission pilot project in SG Cop. of China. Electr Power 2005;38(12):1–5 ([in Chinese]).
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Zhang Yunzhou. Characteristics and development tendency of main frame-work in the future for regional power grid in China. Electr Power 2005;38 (1):1–6 ([in Chinese]).
Research on safety and stability of regional power grids in 2020
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Zhou Qinyong, Zhao Liang, Guo Qiang. Research on safety and stability of regional power grids in 2020. Electr Power 2005;38(5):20–4 ([in Chinese]).
Review and brief analysis on power system accidents and sugges-tions on power system dispatching and management
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Yang Cai. Review and brief analysis on power system accidents and sugges-tions on power system dispatching and management. Power Syst Technol 2007;31(11):6–10.
Review on the blackout of power systems and discussion on its security lessons and related countermeasures
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Kuo Xin, Xiaochen Wu, Shizhi He. Review on the blackout of power systems and discussion on its security lessons and related countermeasures. South Power Syst Technol 2013;7(1):32–8.
WSCC disturbance on august 10, 1996 in the United States
  • Lu Weixiu
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Lu Weixiu, Shu Yinbiao, Shi Lianju. WSCC disturbance on august 10, 1996 in the United States. Power Syst Technol 1996;20(9):40–2 ([in Chinese]).
Revelation of 2.4 Blackouts happened in Brazil on safe and stable operation of China′s power grid
  • Lin Weifang
  • Tang Yong
  • Sun Huadong
  • Guo Qiang
  • Zhao Hongguang
  • Zeng Bing
Lin Weifang, Tang Yong, Sun Huadong, Guo Qiang, Zhao Hongguang, Zeng Bing. Revelation of 2.4 Blackouts happened in Brazil on safe and stable operation of China′s power grid. Autom Electr Power Syst 2011;35(9):1–5 ([in Chinese]).
The management of disasters
  • Coppola Damon
Coppola Damon P. The management of disasters. 2nd ed.Introduction to international disaster management; 2011; 1–35.
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