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Adaptive distance relay setting for parallel transmission network connecting wind farms and UPFC
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... For the accurate operation of distance relays placed into transmission lines connecting large wind farms [12], a time-domainbased method and least square algorithm are discussed. The tripping boundaries [13,14] and relay setting [15,16] of distance relay connected under large WF is adaptively modified to be compliant with various operating scenarios of the WF. In [13,14] only ground faults are considered. ...
... The tripping boundaries [13,14] and relay setting [15,16] of distance relay connected under large WF is adaptively modified to be compliant with various operating scenarios of the WF. In [13,14] only ground faults are considered. In [15], the equivalent impedance of WF and grid side and in [16] the WF equivalent impedance is initially required for the calculation of the relay boundary. ...
... • The advanced distance relay schemes [11][12][13][14][15][16][17] under large WF integration are mainly focused on the performance improvement of distance relay in zone-I. As the higher operating zones of distance relay are more prone to maloperation, to improve the relay performance, an alternate strategy is needed in higher operating zones under large wind power generation. ...
The impedance seen by the distance relay is highly prone to disturbances and major cause of wide-area blackouts. The source impedance of grid-connected large wind farms is variable in nature and thus affects the impedance measured by the distance relay. During faulty conditions, this variation in impedance is responsible for the inaccurate identification and localization of faults using the distance relay. This article presents a system integrity protection scheme (SIPS) for accurate fault localization and classification for supervising the higher operating zones operation of distance relay integrated with the network having large wind power integration. Simulations are carried out on a modified wind farm integrated IEEE-14 bus test system on the PSCAD platform. The proposed SIPS measures the voltage signals using a wide area monitoring system (WAMS). The discrete wavelet transform (DWT) of voltage signals measured from different locations are utilized for information extraction. The detailed coefficient of DWT is further extracted to get the feature sets to reduce the data size. Due to the large feature set, random forest (RF) is used for feature ranking to select important features. Finally, the selected features are utilized for the classification and localization of faults using the RF classifier that further supervises the operation of the distance relay. The results of the RF-based classifier are compared with the ANN classifier with multiple and selected features. The proposed SIPS accurately supervised the relay operation during faulty conditions under large wind power generation.
... Therefore, the voltage and current phasor information used by DFT to calculate impedance in distance, differential, and directional protection schemes is not appropriate for the wind integrated gearbox systems (WITS). To improve the performance of the conventional relays, adaptive distance relay schemes [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26], differential schemes [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43], and directional relay algorithms [44][45][46][47][48][49][50][51][52] were presented. These adaptive methods, which were described in , are trustworthy for a variety of fault types with varying locations and inception angles. ...
... The majority of the works fall within the categories of differential and distance relay mechanisms. A few additional studies that are comparable to these are found in the literature under the other relays category [44][45][46][47][48][49][50][51][52]. To demonstrate the improper operation during failures caused by the wind farm's inadequate feed characteristics, the directional pilot protection scheme is tested on WITS [44]. ...
... These elements have an impact on the classic directional relay's dependability and security. Therefore, the researchers in [46][47][48][49][50][51][52] suggested improved strategies. The internal faults on WITS are detected and distinguished in [46] using the directional angle of the wind side current and collector bus voltage. ...
In the present scenario, renewable energy sources are more encouraged to produce power because of their environmental and economic benefits and wide availability. Furthermore, there are further security concerns regarding the feasibility of incorporating bulk wind technology into the existing electrical grid, especially at the transmission level. This article summarizes the modifications made to the current protection system as a result of the integration of large wind farms. Signal distortions are studied in relation to the effects of dynamic fluctuations in the wind parameters, together with the fault and gearbox line parameters. The use of flexible AC gearbox systems (FACTS) and the integration of large amounts of wind energy have made the situation much worse. Different configurations of the potential solutions for such a gearbox system in the presence of both wind and FACT compensating devices are described. In addition to post-fault diagnosis problems brought on by structural changes in the power system, this research also illustrates fault detection of the transmission lines in the presence of bulk wind power. However, the plans put in place after taking the wind system into account need to be secure when the electricity system is running under stress. To demonstrate the impact of power swing and other stressed events, a review of the solutions is given. Useful techniques like signal processing and artificial intelligence are discussed, which are used to obtain enhanced solutions against conventional methods to get better solutions while protecting lines penetrated through wind farms and equipped with FACT devices. A brief discussion is held regarding the advantages that the new solutions have over the conventional ones.
... Several schemes have been proposed to overcome the over-and under-reach problems associated with the conventional distance relays [8][9][10][11][12][13][14][15][16][17][18][19]. The relay settings [8] and tripping boundaries [9,10] of the distance protection have been adapted to comply with the different operating conditions of the WF. ...
... Several schemes have been proposed to overcome the over-and under-reach problems associated with the conventional distance relays [8][9][10][11][12][13][14][15][16][17][18][19]. The relay settings [8] and tripping boundaries [9,10] of the distance protection have been adapted to comply with the different operating conditions of the WF. However, the equivalent impedances of both grid and WF sides are required to estimate the new relay settings [8], and the ground faults were only considered [9,10]. ...
... The relay settings [8] and tripping boundaries [9,10] of the distance protection have been adapted to comply with the different operating conditions of the WF. However, the equivalent impedances of both grid and WF sides are required to estimate the new relay settings [8], and the ground faults were only considered [9,10]. In [11], an additional adaptive unit has been integrated with the conventional relay to comply with the different operating conditions of the WF. ...
The fluctuated output power of the large-scale wind farms (WF) and their fault transient characteristics have an adverse effect on the current differential protection systems of the transmission lines. With increased transmission line length and in the case of weak output power from the WF, the differential current between both line ends increases in normal conditions since the capacitive current is comparable to the load current. This paper proposes a new differential protection algorithm for transmission lines connected to large-scale wind farms. The proposed current differential protection algorithm is developed based on the signs of the phase current samples at both line ends, instead of utilizing directly the current magnitudes. The similarity between the signs of the phase current samples at both line ends is evaluated utilizing the signed correlation criterion, and the fault detection index is calculated to discriminate the internal faults from other events. In addition, a new online technique is introduced to adjust the protection settings considering the different output power levels of the WF. The conducted PSCAD/EMTDC simulation studies confirm the acceptable performance of the proposed protection algorithm for numerous normal and fault scenarios, including different fault resistances and inception angles as well as all fault types. The effect of line length, type of wind turbine generator, and different values of WF output power are also considered.
... However, all the above adaptive distance relays [5][6][7][8][9][10][11][12][13][14][15] are applied only for the single-circuit transmission line connected to the wind farm. The author has found that only one research article introduces an adaptive distance relay setting for parallel transmission lines connected to wind farm including UPFC [16]. The settings of distance relays are highly affected by the presence of potential coupling between parallel circuits because the apparent impedance is greatly affected. ...
... The settings of distance relays are highly affected by the presence of potential coupling between parallel circuits because the apparent impedance is greatly affected. However, the algorithm in [16] considers only single-line to ground faults and the equivalent impedance of the WTG is required to obtain the new settings. ...
... The proposed protection technique is evaluated with respect to the latest protection algorithms for the double-circuit line connected to large-scale wind farms in the literature [14][15][16] as shown in Table 7. Both proposed technique and that in [16] are applied to the double-circuit line, while the algorithms in [14,15] are applied to the single-circuit line. ...
The penetration of large‐scale offshore wind farms in power grids has a negative effect on the operation of the conventional distance relays. In this study, a new protection technique is presented for uncompensated/compensated double‐circuit transmission lines utilising one‐end current measurements. The proposed protection technique does not require any information regarding the transmission line parameters, wind farms, or the compensation devices. In addition, the errors in phasor estimation due to the generated sub‐harmonics and inter‐harmonics by the wind generators are avoided as the current samples are directly used. Comprehensive studies are implemented on PSCAD/EMTDC software considering numerous cases of external and internal faults. In addition, the double‐circuit transmission line is modelled using the frequency‐dependent phase model and the mutual‐coupling between both circuits are considered. The recorded results confirm the high efficacy of the proposed protection technique with respect to fault type, fault location, and fault resistance.
... But due to the variability nature of renewable sources, it affects the existing protection philosophy of transmission systems and the operator has to pay special attention for the design of protection schemes for transmission systems integrated with renewables. Particularly, the design of protection schemes for compensated transmission lines under these conditions becomes more complicated [38]. Various protection schemes have been used for transmission line protection, namely distance protection, overcurrent protection, differential protection and directional pilot protection. ...
... The variation in wind parameters significantly affects the reach of the distance relays set for transmission line protection. The effect due to wind farm loading on the trip boundary setting of the distance relay, having quadrilateral characteristics, has been discussed in [38], [41]- [45] in detail. As fluctuations in the wind speed causes variations in the voltage level of the local network buses, this leads to changes in the apparent impedance seen by the protective relay [38], [42], [46], [47]. ...
... The effect due to wind farm loading on the trip boundary setting of the distance relay, having quadrilateral characteristics, has been discussed in [38], [41]- [45] in detail. As fluctuations in the wind speed causes variations in the voltage level of the local network buses, this leads to changes in the apparent impedance seen by the protective relay [38], [42], [46], [47]. This fluctuated impedance seen by the protection relay also causes changes in the reach setting of the relay [41], [43]- [45]. ...
... Por otro lado, [6] propone una metodología de ajuste utilizando la característica cuadrilateral, teniendo como resultado el cambio del límite de actuación del relé durante la variación de la impedancia medida, debido a la inserción de la resistencia de falla. ...
... Zona 3: equación (6). ...
Este artículo propone una metodología para ajustar la protección de distancia (ANSI-21) en sistemas de potencia que integran energías renovables no convencionales (ERNC). Se utiliza el sistema New England de 9 barras IEEE modificado como caso de estudio, con un parque eólico compuesto por 33 aerogeneradores de 2.5 MW y sistemas de control validados según estándares internacionales, como el IEC60909-2016. Se considera un valor de resistencia de falla calculado mediante el método de Warrintong. Los ajustes propuestos se simulan utilizando el software Digsilent Power Factory® y un relé Siemens 7SA522 con características cuadrilaterales. La metodología se basa en el uso de datos de voltaje y corriente de los transformadores de instrumentación para calcular la impedancia de la línea hasta el punto de falla. El método adaptativo propuesto demuestra un rendimiento positivo en distintos escenarios de cortocircuito, donde varían el lugar de la falla, la resistencia de la misma y las fluctuaciones de potencia del parque generador. Esto demuestra que el relé actúa en la zona de protección adecuada de manera efectiva.
... The effects of both DFIG-based WFs and FACTS devices on the performance of distance relays in transmission lines are studied. [46][47][48] The effects of offshore WF and UPFC are investigated individually and simultaneously on the performance of distance relays for single-phase-to-ground faults, which occur with high probability in transmission systems. 46,47 The effects of both DFIG-based WFs and FACTS devices of SVC and STATCOM types on the performance of distance relays in transmission lines are studied, 48 and an adaptive distance protection scheme is proposed to improve conventional distance protection performance in FACTS (SVC and STATCOM)-compensated transmission lines for high-resistance single-phase-to-ground faults in a power system that includes WFs. ...
... [46][47][48] The effects of offshore WF and UPFC are investigated individually and simultaneously on the performance of distance relays for single-phase-to-ground faults, which occur with high probability in transmission systems. 46,47 The effects of both DFIG-based WFs and FACTS devices of SVC and STATCOM types on the performance of distance relays in transmission lines are studied, 48 and an adaptive distance protection scheme is proposed to improve conventional distance protection performance in FACTS (SVC and STATCOM)-compensated transmission lines for high-resistance single-phase-to-ground faults in a power system that includes WFs. ...
This paper proposes an adaptive characteristic for eliminating the adverse effects of fault resistance and static synchronous compensator (STATCOM) on the performance of distance relays in transmission line and collector lines of doubly-fed induction generator (DFIG)-based wind farms in the case of single-phase-to-ground resistive faults. The proposed method improves the performance in distance relaying and maintains the coordination between relay pairs in the transmission line and wind farm collector lines. In this method, an adaptive coefficient that can modify the zone settings of conventional distance relays is added to their characteristic to improve the accuracy and coordination under the mentioned conditions. Using analytical relationships and numerical results from simulations in Matlab/Simulink environment, the efficiency of the proposed method is confirmed.
... The wind farm loading effect on the distance relay is having quadrilateral characteristics. [34][35][36][37][38][39]. fluctuation in the wind speed makes variation in the voltage levels in the local networks and hence it ultimately affects the impedance seen in the relays. ...
... fluctuation in the wind speed makes variation in the voltage levels in the local networks and hence it ultimately affects the impedance seen in the relays. [34,36,40,41]. ...
The prime requirement for the improvement of quality of life and the socio- economic condition of any nation is the clean and environment friendly energy harvesting. India, the 2nd highest populous country with a population of 1.39 billion is one of the largest consumers of using fossil fuels in the world. Limited availability of the fossil fuels may obstruct the future socio-economic development. Hence India government motivates the use of renewable energy sources. The renewable energy sources like solar, wind and biomass etc will never diminish their availability. Sunlight is used to meet ever increasing energy need. The literature analysis shows that in India fossil fuels still continues to contribute 80% and renewable energy sources around 20% of the total electricity generation. It is now of prime importance to focus on the technologies and the protection challenges of renewable energy sources in Indian context. The author has reviewed more than 300 research articles and presented various analysis reports. This will definitely help the researchers to find the lacuna behind less contribution of the renewable energy sources.
Keywords: Renewable energy, wind energy, solar energy, biomass energy, renewable energy technology.
... In [11], the influence of the frequency deviation feature of the fault current contributed from a doubly fed induction generator (DFIG)-based wind farm on distance protection is exhaustively investigated and a corresponding solution is proposed in [12]. With the consideration of the mutual coupling effect, the work in [13] points out that the trip boundaries of the conventional distance relay are more easily affected when the wind farm is connected through a single terminal transmission line compared to a double terminal transmission line. As a remedy, an adaptive distance relay setting principle is proposed in [13] and is further applied to the shunt-FACTS compensated transmission line connected with wind farms in [14]. ...
... With the consideration of the mutual coupling effect, the work in [13] points out that the trip boundaries of the conventional distance relay are more easily affected when the wind farm is connected through a single terminal transmission line compared to a double terminal transmission line. As a remedy, an adaptive distance relay setting principle is proposed in [13] and is further applied to the shunt-FACTS compensated transmission line connected with wind farms in [14]. Similarly, another adaptive distance protection scheme aiming at the wind farm connection environment is proposed in [15]. ...
With high sensitivity and strong tolerance capability for the fault resistance, the fault component-based directional relay (FCBDR) has drawn considerable attention from industry and academia. However, the best application environment for FCBDR no longer exists when considering the large-scale connection of the doubly fed induction generator (DFIG)-based wind farms. Through a detailed analysis of the superimposed impedance of DFIG, this paper reveals that the performances of FCBDRs may be shown negatively impacted by the fault behaviors of DFIG when the crowbar protection inputs. In addition, this paper proposes a mitigation countermeasure to deal with those issues. The proposed countermeasure takes advantage of the different superimposed impedance features of DFIG compared with that of the synchronous generator (SG) to enhance the adaptability of the conventional FCBDRs. Extensive simulation results show that the proposed countermeasure can differentiate the fault direction clearly under different fault conditions.
... and static synchronous compensated (STATCOM) transmission line. In [7] , an adaptive distance relay algorithm is proposed for double circuit transmission system equipped with unified power flow controller (UPFC).In [8] , a permissive overreach transfer trip (POTT) scheme is applied to doubly fed induction generator (DFIG) based wind farm. The selectivity feature of protective relay is difficult to achieve for a transmission system integrated with DFIG based wind farm [9] . ...
... So, the values of Z x and Z x depends mostly on the location of the fault ( x ). From (2) , the fault can be detected by using the following condition | I P − I W | > ν (7) where ν is the threshold. In this work, for the selection of threshold value optimization technique is used. ...
Conventional differential protection scheme utilizes a fixed threshold to detect the fault in a transmission system. In a wind integrated transmission system, any fixed threshold-based protection function is not reliable always due to the dynamic variation of control parameters of the wind turbine. To mitigate this issue, an adaptive differential protection scheme is proposed in this work for the transmission system integrated with wind farm. The method uses a particle swarm optimization (PSO) algorithm to generate an optimum threshold for the system considering the varying system and fault operating conditions. An objective function is designed for PSO considering the fault location, inception angle, and fault resistance. The method is tested by using a standard wind integrated transmission system model, simulated using MATLAB software. Performance of the method is tested for numerous test cases considering the wide variations in fault and system operating conditions.
... Adaptive distance relay setting for series compensated line has been discussed in [16]. Recently, the simultaneous impact of unified power flow controller and off-shore wind penetration on distance relay characteristics have been proposed in [17,18]. Moreover, the adaptive direct under reaching transfer trip protection scheme for three-terminal line discussed in [19]. ...
... P m aV 3 w , where P m is the power extracted from the wind in watts; V w (m/s) is wind speed at hub height upstream of the rotor). Therefore, the frequency and voltage fluctuation happens due to speed variation [17,18]. The impact of off-shore WF on apparent impedance trajectory for A-G fault after SVC and STATCOM is shown in Fig. 4d. ...
To improve the performance of the conventional distance protection scheme for compensated lines with high resistance faults, an adaptive distance protection scheme is proposed. This study presents an analytical approach for finding the possible impacts of shunt connected flexible AC transmission systems (FACTS) devices such as static synchronous compensator/static volt-ampere reactive (VAR) compensator (SVC) integrated with off-shore wind farm (WF) on distance relay characteristics. Analytical results are presented and verified on simulation platform compares under reach phenomena in presence of both FACTS devices and it is found that under reach is more severe for SVC connected system. Moreover, presence of SVC changes the line characteristic presented to relay even for bolted faults. It is also seen that type of coupling transformer has a considerable effect on apparent impedance. Furthermore, the reach setting of the relay is significantly affected as the relay end voltage and power fluctuates continuously (due to non-linear relationship with speed) when off-shore WFs are connected to power transmission systems. Thus, adaptive tripping characteristics for high resistance line-to-ground fault with shunt-FACTS devices considering appropriate operating conditions is a demanding concern and the same has been addressed in the proposed research work.
... In an attempt to address these issues, the negative effects of using FACTS on transmission line distance protection systems are presented in [3,[8][9][10][11][12][13][14][15]. ...
... In [15], the author presents an adaptive formulation to protect transmission lines compensated via STATCOM based on synchronized measurements. A study of the effects of UPFC on distance protection and novel adaptive distance protection methodologies is presented in [8,[12][13][14]. ...
... Using local knowledge of current, voltage, and the number of WF units, an adaptive distance relay strategy is developed to protect the transmission system connected to a WF in [12]. An online adaptive distance relay setting for parallel transmission networks having FACTS with WFs is suggested in [13]. ...
Protective relays can mal-operate for transmission lines connected to doubly fed induction generator (DFIG) based large capacity wind farms (WFs). The performance of distance relays protecting such lines is investigated and a statistical model based intelligent protection of the area between the grid and the WF is proposed in this article. The suggested method employs an adaptive fuzzy inference system to detect faults based on autoregressive (AR) coefficients of the 3-phase currents selected using minimum redundancy maximum relevance algorithm. Deep learning networks are used to supervise the detection of faults, their subsequent localization, and classification. The effectiveness of the scheme is evaluated on IEEE 9-bus and IEEE 39-bus systems with varying fault resistances, fault inception times, locations, fault types, wind speeds, and transformer connections. Further, the impact of factors like the presence of type-4 WFs, double circuit lines, WF capacity, grid strength, FACTs devices, reclosing on permanent faults, power swings, fault during power swings, voltage instability, load encroachment, high impedance faults, evolving and cross-country faults, close-in and remote-end faults, CT saturation, sampling rate, data window size, synchronization error, noise, and semi-supervised learning are considered while validating the proposed scheme. The results show the efficacy of the suggested method in dealing with various system conditions and configurations while protecting the transmission lines that are connected to WFs.
... The mutual-impedance of positive and negative sequence could be neglected, however the mutual-impedance of the zero-sequence system between the lines has to be considered for any further studies of doublecircuit power transmission relaying schemes. The mutualimpedance of double lines can be eliminated by using transposition of lines, but even that, the mutual zero sequence impedance would not be zeroes [15,16]. Therefore, the mutual zero sequence impedance is pointedly disturbing the sources voltage. ...
... For double-circuit transmission lines connected to a large scale wind farms, only an adaptive distance relay setting has been proposed in [25]. However, the fault location issue is not introduced in this paper. ...
This paper introduces a new time-domain fault location algorithm for two-terminal parallel transmission lines connected to large scale wind farms. The proposed algorithm employs only a half-cycle data window of synchronized current samples at both line terminals to avoid inaccurate estimation of current phasors due to the generated sub- and inter-harmonics currents by the wind farms. The proposed algorithm does not need any transformation method to decouple the double-circuit transmission line. Moreover, it takes into consideration the effect of the line asymmetry and the potential couplings between the six phases. The fault location equation is deduced by equalizing the differential components of the calculated instantaneous voltages at the fault point, and then the fault distance is estimated directly without any iterative algorithm. The two-terminal parallel transmission line is emulated by PSCAD/EMTDC platform utilizing the frequency-dependent phase model, and the required calculations for fault location are conducted by MATLAB software. The proposed algorithm is tested for several fault resistances and fault locations, and all fault types, including cross-circuit faults. In addition, the effect of measurement, synchronization, and line parameters errors on the fault location accuracy is investigated. The obtained results confirm acceptable accuracy of the proposed fault location algorithm.
... Amin et al. proposes a wind energy conversion system controller based on the synchronverter concept to solve the stability of an offshore wind power network [26]. Sadeghi, Dubey et al. propose two new and adaptive distance protection [27,28], and Sadeghi et al. designes an adaptive unit for distance relay using artificial neural networks. Dubey et al. ...
The system impedance instability, high-order harmonics, and frequency offset are main fault characteristics of wind power system. Moreover, the mea-surement angle of faulty phase is affected by rotation speed frequency component, which causes traditional directional protections based on angle comparison between voltage and current to operate incorrectly. In this paper, a time-domain protection for connected to wind power plant based on model matching is pro-posed, which compares the calculated current and the measured current to identify internal faults and external faults. Under external faults, the calculated current and measured current waveform are quite similar because the protected transmission lines is equivalent to a lumped parameter model and the model itself is not damaged. However, the similarity of calculated current and measured current is quite low, due to destroyed integrity of model under internal faults. Additionally, Hausdorff distance is introduced to obtain the similarity of the calculated current and measured current. Since the proposed protection scheme is applied in time domain, it is independent from current frequency offsets of wind energy system, high-order harmonics, and system impedance variations. Comprehensive case studies are undertaken through Power Systems Computer Aided Design (PSCAD), while simulation results verify the accuracy and efficiency of the proposed approach in fault identification.
... An adaptive and modified version of distance protection scheme, considering influence of UPFC, was proposed in [3]. In [4], an adaptive distance relay scheme for wind and UPFC connected parallel transmission lines is reported. Fault classification in transmission lines, equipped with FACTS devices, using decision tree was introduced in [5]. ...
Fault analysis (detection, classification and location) of transmission network is of great importance in power system. A Wavelet-Alienation-Neural (WAN) depended protection technique has been developed for the fault analysis of Unified power flow controller (UPFC) compensated transmission network. The detection and classification of various outages are accomplished by alienation of wavelet based approximate coefficients computed from current signals. The precise location of faults is carried out by an Artificial Neural Network fed from estimated coefficients computed from voltage and current signals within the same quarter cycle. The robustness of the algorithm is proved with the case studies of varying fault locations, sampling frequency, system parameters, effects of noise, fault incipient angle, different control strategies and fault path impedances.
... This motivated an improved AP scheme design using more system information like the mutual coupling, wider range fault resistances, and the power swing impact parameters for better performance [42], but the model does not cover the compensated transmission line system networks under WFER integration. Further improved AP for both compensated with integrated WT sources on the same utility grid system is presented [39], [43]. The complexity of the approach is the channeling factor. ...
... Some studies have analyzed the impact that renewable energies based on PE may cause in traditional protection system behavior from a theoretical point of view and using traditional simulation analysis [6][7][8][9][10]. Focusing on distance protection in high PE penetration systems, [11][12][13][14][15][16] show different adaptive settings approaches but they are only focused on solving under-reach or over-reach problems associated to renewable generation and does not take into account missed trips due to directional or phase selection errors. Furthermore, [14][15][16] only analyzes current contribution under balanced fault. ...
The high penetration of renewable energies will affect the performance of present protection algorithms due to fault current injection from generators based on power electronics. This paper explains the process followed for analyzing this effect on distance protection and the development of a new algorithm that improves its performance in such a scenario. First of all, four commercial protection relays were tested before fault current contribution from photovoltaic system and full converter wind turbines using the hardware in the loop technique. The analysis of results obtained, jointly with a theoretical analysis based on commonly used protection strategy of superimposed quantities, lead to a conclusion about the cause of observed wrong behaviors of present protection algorithms under a high penetration of renewables. According to these conclusions, a new algorithm has been developed to improve the detection of faulted phase selection and directionality on distance protection under a short circuit current fed by renewable energy sources.
... The transmission networks face different protection challenges due to bulk penetration of the wind power including under/overreach issue of the relays due to change of fault impedance [110]. In response, many protection schemes have been proposed including adaptive logic program based scheme [111], adaptive distance relay setting scheme [112], support vector machine-based scheme [113], data-mining-based intelligent differential relaying [114], and wavelet and Fourier Transform based differential relaying [115]. The level of fault current, in addition to the selection and coordination of protective devices, are the main challenges of the microgrids incorporated with the wind [110]. ...
The strengthening of electric energy security and the reduction of greenhouse gas emissions have gained enormous momentum in previous decades. The integration of large-scale intermittent renewable energy resources (RER) like wind energy into the existing electricity grids has increased significantly in the last decade. However, this integration poses many operational and control challenges that hamper the reliable and stable operation of the grids. This article aims to review the reported challenges caused by the integration of wind energy and the proposed solutions methodologies. Among the various challenges, the generation uncertainty, power quality issues, angular and voltage stability, reactive power support, and fault ride-through capability are reviewed and discussed. Besides, socioeconomic, environmental, and electricity market challenges due to the grid integration of wind power are also investigated. Many of the solutions used and proposed to mitigate the impact of these challenges, such as energy storage systems, wind energy policy, and grid codes, are also reviewed and discussed. This paper will assist the enthusiastic readers in seeing the full picture of wind energy integration challenges. It also puts in the hands of policymakers all aspects of the challenges so that they can adopt sustainable policies that support and overcome the difficulties facing the integration of wind energy into electricity grids.
... Thorough investigations on recent global practices in the deployment of many types of environmentally attention should be paid to the design of protection schemes for transmission systems integrated with large-scale renewables. Particularly, the design of protection schemes for compensated transmission lines under these conditions becomes more complicated [8]. ...
... This will cause maloperation 2 in presence of shunt FACTS, depending on the system configuration. 3,4 The zone variation in presence of FACTS device in inductive mode is more than capacitive mode. 3 Distance relay reach accuracy is affected by shunt capacitance and mutual coupling of parallel lines. ...
Numerical distance relays are used in modern power system to boost the performance and reduce the computational burden of relay. Quadrilateral zone of distance relay is more suitable and capable of boundary modification on protection scheme. In this paper, an adaptive distance relay is introduced to tackle the maloperation problems encountered in non-uniform structure of combined transmission system, in which the zone 1 of distance relay is modified. Two boundaries are modified with fifth degree of polynomial equation for quadrilateral zone characteristic. Appropriate objective functions are defined to minimize the increment in relay zone, maloperation rate, and boundary accuracy error. The multiobjective optimization problem is solved by using genetic algorithm. According to the extensive computational analysis results performed by MATLAB, the high accuracy of the proposed adaptive relay was achieved. Furthermore, the proposed method has the ability to encompass all faults and tackles the influence of various power system conditions by finding the optimized equation coefficients for the nonuniform structures.
... The adaptive distance relay setting for two terminal transmission networks with SSSCs is proposed, and extensive validations are conducted. Furthermore, the performance of an adaptive relay is also tested for stress conditions, such as power swing, faults during power swing [36][37][38][39][40] , and load encroachment conditions. The relay must not respond to power swing and load encroachment and must effectively work for faults during power swing. ...
This article presents an extreme learning machine based fast and accurate adaptive distance relaying scheme for transmission lines in the presence of a static synchronous series compensator. The ideal trip characteristics of the distance relay is greatly affected by pre-fault system conditions, ground fault resistance, and zero-sequence voltage. The proposed research develops an extreme learning machine based adaptive distance relaying scheme for two-terminal transmission networks with static synchronous series compensators when a single-line-to-ground fault situation is most likely to occur. The study includes an analytical approach, including a steady-state model of static synchronous series compensator with detailed simulation on MATLAB/Simulink (The MathWorks, Natick, Massachusetts, USA) and open real-time simulation software with MATLAB (OPAL-RT) platform (OPAL-RT Technologies, Montreal, Quebec, Canada). The proposed extreme learning machine based adaptive distance relaying scheme is extensively validated on the two terminal transmission lines with static synchronous series compensators, and the performance is compared with the existing radial basis feed-forward neural network based adaptive distance relaying scheme. The results on simulation and real-time platform show significant improvements in the performance indices, such as speed, selectivity, and reliability of the digital relay. 2016
... The fault location versus compensation factors for power system (Figure 10) is shown in Figure 11(a). The impact of shunt capacitance on the fault current is negligible and thus, the Shunt capacitance during fault analysis is neglected [20, 21]. This is normally considered to avoid complex mathematical burden. ...
The paper presents an on-line sequential extreme learning machine (OS-ELM) based fast and accurate adaptive distance relaying scheme (ADRS) for transmission line protection. The proposed method develops an adaptive relay characteristics suitable to the changes in the physical conditions of the power systems. This can efficiently update the trained model on-line by partial training on the new data to reduce the model updating time whenever a new special case occurs. The effectiveness of the proposed method is validated on simulation platform for test system with two terminal parallel transmission lines with complex mutual coupling. The test results, considering wide variations in operating conditions of the faulted power network, indicate that the proposed adaptive relay setting provides significant improvement in the relay performance.
... The performance of the proposed ELM based FADRS are tested under stressed condition such as power swing [18][19][20][21][22][23][24]. Power swing is one of the major issues and the relay must perform accordingly. ...
The power electronic device-interfaced ac system becomes an important scene of renewable energy power system. The response of the power-electronic devices confronting faults is restricted by their overcurrent withstand capability, showing weak-feed characteristic. Therefore, the sensitivity of protection can be ensured only when the fault can be located before fault ride through of power-electronic device. In this paper, the expression of fault traveling wavefront is derived first and it is pointed out that the expression contains two terms, which are power frequency sine term and exponential decay term. The index of the exponential decay term is only determined by fault distance, whereas the fault occurrence time, fault type, and fault impedance only influence amplitudes of the two terms. In this way, the fault distance and fault severity can be characterized by index and amplitude coefficients respectively and thereby be decoupled. On this basis, an algorithm is proposed to extract fault distance and fault severity information from wavefront, then a novel protection principle is proposed using fault distance information contained in wavefront. The proposed wavefront protection can fast locate faults and have higher sensitivity and reliability compared with the existing non-unit protections, which is verified by numerous simulations and experimental tests.
In recent years, wind energy technology (WET) has been a promising alternative to meet the growing power demand worldwide. This technology is gaining popularity due to its cleanliness and economic attractiveness. Among the various turbine generators (TGs) in WET, the Type-3 doubly-fed induction generator (DFIG) and Type-4 permanent magnet synchronous generator (PMSG) is the most used and technically attractive TGs in large-scale wind power generation. The wind farm consists of several such TGs integrated into the main utility grid and the generated large power is injected through high voltage (HV) long transmission lines (TLs). Therefore, an adequate distance relaying is provided in the long TL for an uninterrupted power supply to the main utility grid. However, the impedance of the TL is greatly affected both during fault and normal conditions due to the nonlinear wind speed versus generated power characteristics, complex control action, and low voltage ride-through capability of the TGs. It confounds the operation of the traditional fixed impedance-based distance relay protecting the TL during fault. These motivate to develop the advanced relaying schemes to provide accurate protection to such TLs. For this purpose, numerous research works have been published over the last decade. The present paper discusses the various impacts of grid-integrated large-scale wind farms on distance relaying-based transmission line protection schemes first. Further, it provides a comprehensive chronological review of the relaying schemes available in the literature to mitigate the protection problems of such wind farm integrated crucial transmission lines. This study may be found useful for future research and to gain insight into the scope of protection of HV-TLs connected to large-scale wind farms for further development.
This chapter examines the control and design of hybrid off-grid configurations using renewable and non-renewable energy sources (R&NR-ESs). Details relating to power quality, voltage, frequency regulation, and synchronization between off-grid configuration elements are provided. Analyzing and testing a hybrid off-grid configuration based on a solar PV array (SPA) and a variable speed doubly fed induction generator (DFIG) is done to better understand this technology. A rotor side converter (RSC) is designed with improved vector control to vary the speed of the diesel engine accordingly to load power demand, generated power from SPA, and battery charge level. To achieve maximum power point tracking (MPPT) from SPA, an improved Perturb and Observe algorithm (IP&O) is used. Improved oriented stator flux control is designed to maintain constant the PCC voltage and frequency, as well as improve the power quality (PQ) at the point of common coupling (PCC) for load-side converters (LSC). An algorithm based on a proportional–integral controller that prevents the BES from overcharging is employed. Simulations are conducted using MATLAB/Simulink to evaluate the performance of selected hybrid off-grid configurations and their control strategies.KeywordsOff-microgrid configurationRenewable and non-renewable energy sourcesVariable speed diesel generatorDFIGControl systemPower quality improvement
Microgrid is an important component of the evolving smart-grid. It has the ability to increase reliability, decrease costs, and enlarge penetration rates for distribution generation systems. However, the protection coordination may get badly affected due to the bi-directional/variable power flow associated with microgrid system and increasing penetration rates of distributed energy resources. Therefore, a proper protection strategy is highly required to decrease the complexities associated with microgrid system. In this paper, a widespread literature review on the current research and progression in the field of AC-microgrid protection is presented. The prime objective of this survey is to extend the researcher’s database comprising relevant reference points which could be highly beneficial to their future research work. This work comprises of the current status, major hitches and existing research efforts focussed in the direction of providing a smooth relaying system under diverse MG operating conditions. Moreover, the work concentrates on analysing the intelligent approaches/devices that help transform the present protection schemes to become smarter.
The use of phase shifting transformer (PST) is one of the common methods of power flow control in complex transmission systems. Changing the power distribution in lines by the PST will change the voltage and the current signals of the power system. Loss of excitation relay in a synchronous generator is one of the important relays of the generator that measures the voltage and current signals of generator output to identify the loss of excitation of the generator. This study shows that the presence of PST in the transmission line interferes with the performance of the loss of excitation (LOE) relay. The LOE relay in this paper is of the Berdy type, which detects loss of excitation by measuring the voltage and current of the generator and calculating the impedance from them. In this paper, the way this impedance is calculated has been modified, as this impedance is calculated from the modified values of the active and reactive powers of the generator. As a result, it has been shown that with the help of this method, the effect of PST on the operation of the LOE relay is significantly eliminated. In the proposed method, PST information is not required to be sent to the relay location, and so the communication channel is not needed. A decision tree‐based method is used as a backup protection to guarantee proper operation in power swing conditions.
To improve the power transfer capability and reliability of the power grid, the unified power flow controller (UPFC) project has been put into operation in the western Nanjing power grid. Based on the practical project, the influence of UPFC on the distance protection is analyzed. To cope with that, the novel three-zone distance protection scheme is put forward. The zone 2 and zone 3 of the novel three-zone distance protection scheme are the same with those of conventional distance protection; however, the novel distance protection zone 1 is based on the parameter model of transmission line. According to the average value and fluctuation degree of the fault distance calculation results, the proposed distance protection zone 1 can effectively distinguish between the internal faults and external faults. More importantly, the proposed distance protection zone 1 can realize effective cooperation with the conventional distance protection zone 2 and zone 3, to construct a complete three-zone distance protection scheme and guarantee the correct operation of the novel three-zone distance protection scheme. The simulation cases in the PSCAD/EMTDC software environment verifies that the proposed three-zone distance protection has excellent performance, and would not be affected by the operational mode and control parameters of UPFC.
An instantaneous converter power based adaptive second order sliding mode control for the Unified Power Flow Controller (UPFC) in a multimachine power system penetrated with a doubly fed induction generator (DFIG) based wind farm is proposed in this paper. Instead of controlling the direct and quadrature-axis currents of the series voltage source converter (VSC) of the UPFC, the instantaneous active and reactive power outputs are used as control variables. This mode of control dispenses the unmodelled dynamics of the VSC phase-locked loop (PLL) system and produces a robust control for the active–reactive power, and DC voltage excursions. However, the PLL is used only to obtain the frequency component needed to generate the Pulse Width Modulation (PWM) signal. In comparison to the first order sliding surface, the second order sliding surface provides very good robustness features, finite reaching time, and chattering free sliding mode behavior. Further, the proposed controller gains of the UPFC are chosen in accordance with the various constraints imposed by the second order sliding mode approach to provide significantly superior and robust performance for a number of diverse operating conditions of the network in comparison to the conventional sliding mode controller.
This paper presents analytical and simulation results of the application of distance relays for the protection of transmission systems employing flexible alternating current transmission controllers such as the unified power flow controller (UPFC). Firstly a detailed model of the UPFC and its control is proposed and then it is integrated into the transmission system for the purposes of accurately simulating the fault transients. An apparent impedance calculation procedure for a transmission line with UPFC based on the power frequency sequence component is then investigated. The simulation results show the impact of UPFC on the performance of a distance protection relay for different fault conditions; the studies also include the influence of the setting of UPFC control parameters and the operational mode of UPFC.
In this paper the impact of Static Synchronous Series Compensator (SSSC) on the impedance calculated by distance relay is investigated. Analytical results are presented and verified by detailed simulations. Six different phase to phase and phase to ground measuring units of the distance relay are simulated to resemble the behavior of the relay. It is shown in this paper that zero sequence of the injected voltage by 48 pulse SSSC converter has the most impact on the apparent impedance seen by the phase to ground fault measuring unit and cause under reaching of distance relay. It can be concluded from the results that SSSC located in the middle of the transmission line cause to divide trip characteristics of distance relay into two separate parts. It is also shown that the over-reaching operation of distance relay might happen in some cases in the presence of SSSC. All the detailed simulations are carried out in MATLAB/Simulink environment.
An adaptive current protection scheme is proposed for the protection of power systems with penetration of distributed generation (DG). In this scheme, steady state fault current of the related power transmission lines is derived from steady state network equivalent reduction. Then, settings criteria for adaptive primary and backup protection are established on the basis of the steady state fault current. The simulated results of a realistic power network verify the ranges of adaptive primary and backup protection are immune to implementation of DG and the fault types. Furthermore, compared with traditional current protection schemes, the proposed method has extended the primary and backup protection regions considerably.
Wind speed variations results in wind farm voltage, frequency and power output fluctuations. Therefore, protection of lines connecting such a farm to the grid is very important and an adaptive system for distance protection of such a line is necessary. In this paper, an adaptive unit which adjusts the relay trip characteristic using local information has been designed for distance relay using artificial neural networks. In this case, in order to prevent wrong operation of relay, changing in wind farm conditions, the set points of different zones of distance relay has to be changed simultaneously. The results obtained from proposed method are verified by computer simulation.
Distance relay protecting series compensated line has limitations with metal oxide varistor (MOV) operation,
prefault system condition, high resistance fault and shunt capacitance. This paper proposes an
adaptive first-zone distance protection scheme for line with fixed series compensation connected at
one end using local measurements. Impedance offered by series capacitor and MOV combination is estimated
using relay end fault current. The method has ability to compensate the error due to high resistance
fault. The technique is tested for different system operating condition, level of compensation and
fault resistance of a 400 kV series compensated line and simulated through EMTDC/PSCAD. Simulation
results demonstrate the effectiveness of the proposed method.
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This paper analyzes the distance relay performance during power swing conditions for an uncompensated and compensated transmission line with a unified power-flow controller (UPFC). UPFC can control voltage and power flow of the transmission line independently; hence, it has an impact on the apparent impedance seen by the distance relay. To analyze the case, the apparent impedance seen by the distance relay during a power swing is extracted, and the results are synopsized graphically. The impact of UPFC on different transmission-line parameters from an impedance point of view is investigated. Moreover, the impact of different operation modes of UPFC and their reference values on the apparent impedance seen by concentric $mho$ circles as a power swing detection method are also evaluated by detailed simulations.
Fault-detection and out-of-step protection functions are two important requirements in distance relays while dealing with power-swing conditions. In the proposed research, the first part focuses on developing wavelet entropy-based out-of-step blocking function during stable power swing and tripping function during unstable power swing. The process starts at retrieving the current signal samples during power swing and process it through wavelet transform to derive singular values, used to find out Shannon entropy, called wavelet singular entropy (WSE). Further, the power swing indicators are computed to distinguish stable power swing from unstable ones. The second part computes WSE-based indicator to distinguish faults from power swing. The WSE blocks the relay during power swing and issue the tripping signal during fault conditions based on a set threshold. The proposed technique is extensively tested for different stable and unstable power swing conditions providing improved response time for fault detection during power swing and distinguishing stable power swings from unstable ones.
Fault during a power swing is a challenging task for the distance relay functioning. This article presents a spectral energy function for fault detection during a power swing using a novel time frequency transform known as the S-transform, a variable windowed short-time Fourier transform, which combines the elements of short-time Fourier transform and wavelet transform. Initially, the current signal is preprocessed using S-transform to generate the S-matrix and corresponding S-contours (time–frequency contours). The spectral energy content of the S-counters is used to register symmetrical and unsymmetrical faults during a power swing and, based on a set threshold on the spectral energy, the relay blocks during a power swing and issue of the tripping signal during fault. The proposed technique is tested for different fault conditions during a power swing with possible variations in operating parameters, including the ability to identify the faults with a response time of 1.25 cycles from the fault inception during power swing.
This text/reference presents a comprehensive, up-to-date account of computer relaying in power systems, based in part on the author's extensive experience in the field. Provides background material on current relaying practices, and covers the mathematical foundations for relaying algorithms. Each chapter contains helpful illustrations, examples, and problems.
Transmission line distance relaying for flexible AC transmission lines (FACTS) including thyristor controlled series compensator (TCSC), STATCOM, SVC and unified power flow controller (UPFC) has been a very challenging task. A new approach for fault zone identification and fault classification for TCSC and UPFC line using decision tree (DT) is presented. One cycle post fault current and voltage samples from the fault inception are used as input vectors against target output dasia1psila for fault after TCSC/UPFC and dasia0psila for fault before TCSC/UPFC for fault zone identification. Similarly, the DT-based classification algorithm takes one cycle data from fault inception of three phase currents along with zero-sequence current and voltage, and constructs the optimal DT for classifying all ten types of shunt faults in the transmission line fault process. The algorithm is tested on simulated fault data with wide variations in operating parameters of the power system network including noisy environment. The results indicate that the proposed method can reliably identify the fault zone and classify faults in the FACTs-based transmission line in large power network.
Reach accuracy of a distance relay is adversely affected by prefault system conditions, ground fault resistance, shunt capacitance, and mutual coupling of parallel lines. This paper presents a comprehensive adaptive relaying scheme for stand-alone distance protection of parallel transmission lines under a single-line-to-ground fault condition taking into account all of these factors. The proposed adaptive scheme is based on the back-propagation neural network used for training and adaptation. The relay acts as a stand-alone relay, which does not require a separate communication channel for real-time data transmission during faults. The simulation results show significant improvement in the relay selectivity.
Summary form only given as follows. The paper presents an apparent impedance calculation procedure for the distance relaying of power transmission lines involving FACTS devices, particularly the UPFC (unified power flow controller). The presence of UPFC significantly affects the trip boundaries which are also adversely affected by fault resistance combined with remote end infeed. Depending on the UPFC location, the trip boundary is influenced by the fault location, prefault condition, the arc fault resistance and the parameters of the UPFC itself (series voltage magnitude and phase angle). The adaptive nature of this protection scheme necessitates the use of a neural network for generation of trip boundaries
A fundamental basis has been developed for the use of a time-shared stored-program digital computer to perform many of the electrical power-system protective-relay functions in a substation. Logic operations are given to detect a fault, locate it, and initiate the opening of the appropriate circuit breakers, whether the fault is in the station or on lines radiating from the station. The instantaneous values of the station voltages and currents are sampled at a 0.5-ms rate, converted to digital form, and stored for computer main-frame use. Operating times are compatible with the 25-ms breaker trip capability of modern two-cycle breakers. Computer speed in initiating tripping is a maximum of 4 ms for severe faults and a maximum of 10 ms for moderate or distant faults. Little attention has been given to hardware or programming aspects; instead this treatment represents the viewpoint of a protective-relay engineer who is attempting to answer the question: can it be done and what is involved? However, major emphasis was placed on minimizing computer main-frame duty. Copyright © 1969 by The Institute of Electrical and Electronics Engineers, Inc.
The European Union has committed to reduce the equivalent carbon dioxide emissions by 8% of the 1990 level by the end of 2012. To meet the objective, the member states have financially encouraged the development of renewable energy especially wind power. Locally, this results in some of the highest wind power penetration levels in the world. This paper discusses the transmission challenges of Denmark, Spain, Germany and Ireland. With increasing wind capacity, the transmission system operators (TSOs) became concerned about the impact of high levels of wind generation on system stability. The integration of wind power has been hampered by the lack of suitable dynamic models for use in transient stability programs. The number of different turbine technologies used increased the complexity of the modeling problems.
Performance of conventional nonpilot distance relay is affected by ground fault resistance, prefault system conditions, mutual effects of parallel lines and shunt capacitance influences. The work presented in this paper addresses the problems encountered by conventional non pilot distance relay when protecting two terminal parallel transmission lines. One of the key points of this paper is the detailed analysis of the apparent impedance as seen from the relaying point taking into account the effects of transmission line parameter uncertainties, mutual effects of parallel lines for simple and more complex configuration, shunt capacitance influences and variations in the system external to the protected line. Based on extensive computer simulations of the infeed/outfeed, fault resistance, mutual coupling and shunt capacitance effects on the relay characteristics, an adaptive digital distance relaying scheme is proposed using radial basis function neural network which provides more efficient approach for training, computation, adaptation and tripping than the conventional feed forward network using back propagation algorithm. In addition, the proposed adaptive scheme improves the performance of distance relay for double-circuit lines using modified compensation factor. Moreover, the scheme does not require separate communication channel for data transmission. The results of computer simulation show the improvement of sensitivity and selectivity of the relay
Due to changes in the power system, such as generator and line
outages and changes in load and generation, the performance of distance
relays can vary. In the case of a distance relay protecting a phase of a
double-circuit line, the state of the parallel circuit is of major
importance. Simulations show that, depending on the power system state,
a distance relay can cover from less than 50% up to far more than 100%
of the total line length. This is demonstrated with a double-circuit
line under the single-line-to-ground fault (SLG) fault condition, since
this is the most common type of fault. In this paper the distance
protection of a double-circuit line under the SLG fault condition is
formulated. To achieve correct operation, the relay does not only use
the measured quantities of the circuit-to-be-protected, but also the
zero sequence current of the parallel circuit. Such a relay requires
extra measuring equipment, and, moreover, the zero sequence current of
the parallel circuit cannot always be measured. Therefore, another
approach is chosen. A correction factor is introduced, set adaptively
according to the actual power system state. In this way, the appropriate
setting of the relay is provided, in relation with the actual power
system state. A side-effect of the adaptive setting of the relay is that
the safety margin in the relay settings is decreased, due to the
uncertainty in the power system state. By adapting the relay to the
actual power system state, maximum selectivity is achieved, and the
protection system as such will be more reliable
Reach accuracy of a distance relay on transmission lines is
adversely affected by fault resistance combined with remote-end infeed
which is not measurable at the relaying point. Different network
conditions correspond to different remote-end infeed behaviour and in
conventional setting a safety margin is necessary so as to avoid
maloperation. In this paper an adaptive setting concept which can
overcome this disadvantage is proposed. A microprocessor based distance
relay with this new technique can respond to network conditions that
change from time to time and computer simulation has confirmed the
validity of this new concept
Wind speed varies continuously throughout a day resulting in fluctuating wind farm output power. When such a farm is connected to the grid through a line, the transmitted power and the relay end voltage (with respect to grid voltage) fluctuate continuously. In this paper, the protection of such a line with distance relay is investigated. The ideal trip characteristic for distance relay is studied with change in conditions of the wind farm. A method is proposed to set the boundary adaptively using local information only
Remote end infeed causes problems in distance relay especially
under high resistance earth fault conditions. Although a distance relay
set to an ideal operating region can cover the fault resistance at one
particular load condition, the operating region is affected by changes
in load condition. Hence a distance relay may overreach or underreach
when load changes. From the main factors which affect the ideal digital
distance relay operating region, a stand alone intelligent digital
distance relay which can adapt to these changes is presented. This
approach does not need communication links from the remote end of the
line or the system control center. Numerous computer simulations have
been carried out on realistic system configurations and the results show
that there is a high potential for developing an intelligent digital
distance relay
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