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Point of Common Coupling From IEEE 519A Applications Guide (Draft)
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IEEE Std 519-1992 is a useful document for understanding harmonics and applying harmonic limits in power systems. Despite many years of good use there is still some confusion about how to apply certain aspects of the standard. This paper discusses some of those, as well as related issues that are helpful in working with harmonic limits. There is co...
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... Five or six solar panel modules are required for a string inverter system [18]. Harmonic voltage distortion is capped at 5.0% by IEEE 519 (THD), with individual harmonics capped at 3% each; the current harmonic caps are determined by the system's short circuit strength [19]. Adding diodes to the model of solar cells would provide a faster computing time, therefore there is a better performance of the photovoltaic (PV) solar cells [20]. ...
There has been a lot of focus in recent years on finding ways to incorporate renewable energy systems, especially solar photovoltaic (PV) systems, into the existing electrical grid. Power conversion technologies that are both efficient and reliable are in high demand due to the expanding popularity of solar photovoltaic (PV) systems. Micro-inverters, which are module-based inverters placed on individual PV modules, have grown in popularity in recent years due to their decentralized design. However, the integration of solar micro-inverter into the electrical grid presents power quality challenges. This research article presents an experimental investigation and power quality analysis of a solar micro-inverter under various operating conditions such as dust and shade.
... Most EPSs have some tolerance for harmonic distortion; however, when the harmonic distortion increases, it will undoubtedly lead to communication failure, line loss, overheating, and circuit breaker tripping [77]. Therefore, HMGs must minimize the emission of harmonic distortion according to current standards and codes [53,[78][79][80][81]. An important index for quantifying the harmonic content of a voltage or current signal is the Total Harmonic Distortion (THD), which expresses the relationship between two magnitudes and the effective value of the harmonic residue or harmonic components with respect to the fundamental component. ...
Microgrids (MGs) are systems that cleanly, efficiently, and economically integrate Renewable Energy Sources (RESs) and Energy Storage Systems (ESSs) to the electrical grid. They are capable of reducing transmission losses and improving the use of electricity and heat. However, RESs presents intermi ent behavior derived from the stochastic nature of the renewable resources available on site. This can cause power-quality issues throughout the electrical grid, which can be solved by different optimization techniques and/or control strategies applied to power converters. This paper offers a detailed review of the literature regarding three important aspects: (i) Power-quality issues generated in MGs both in islanded mode and grid-connected mode; (ii) Optimization techniques used in the MGs to achieve the optimal operating conditions of the Energy Management System (EMS); and (iii) Control strategies implemented in the MGs to guarantee stability, mitigation of power-quality issues, power balance, and synchronization with the grid. It is worth mentioning that in this paper, we emphasize hybrid MGs (HMGs) since they combine the benefits of AC-MGs and DC-MGs while increasing system reliability. As the utility grid moves toward an optimal design of MG structures, this paper will serve as a foundation for future research, comparative analysis , and further development of novel techniques regarding HMGs.
... Most MG sources are renewable energy systems that use a power electronics device to add harmonics to the grid. Because of this, new GC regulations necessitate that MG systems dramatically cut on harmonics emissions to meet these standards [17]. ...
This chapter presents the conceptual application of power quality (PQ) in the microgrid environment. The distortion in the current and voltage waveform is increased by a spike in the penetration of renewable energy producers containing sophisticated power electronics converter modules. Also, renewable energy-based generation is more attractive than conventional non-renewable-based generators due to enhanced environmental, reduced carbon emission, economical and rural energy electrification benefits. Integrating the multiple microgrids into the distribution system forced utilities to look to preserve the quality of power supplied within standard limits. Nowadays, PQ is more critical due to problems arising in equipment malfunctioning, insulation deterioration, and degraded equipment output performances. This chapter will focus on the standards and methods reported in the scientific literature required to assess the PQ in a microgrid environment operating in isolated and grid-connected modes. Further, the chapter will discuss the essentials of various grid codes and standards available for assessment, monitoring, and improvement.KeywordsPower qualityMicrogridRenewable energy generatorsMitigationHarmonicsSagSwell
... THD of sensitive busses in four scenarios is shown in Table 3. According to the table, THD of some sensitive loads in scenarios1-3 exceeds from 5% standard limit [45] which may cause extra costs for DN operators. In the fourth scenario, THD of all sensitive busses is decreased and it remains within the standard allowable range. ...
Distribution network reconfiguration (DNR) is capable to improve indices of power systems by changing the distribution network (DN) topology under normal conditions. Here, DNR is implemented to improve the power quality (PQ) and power losses of DN. Furthermore, to achieve better optimum in DNR, discrete particle swarm optimization (DPSO) algorithm is equipped with a smart radial method. The proposed algorithm is faster than other metaheuristic methods due to the prevention of regeneration non‐radial configurations. In addition, the algorithm increases the probability of finding the optimal configurations using the mutation function. The results clearly demonstrated the positive effect of DNR in improving harmonic losses, total harmonic distortion (THD), and power losses. Furthermore, the proposed method is compared with other metaheuristic algorithms in IEEE 33 bus DN, IEEE 69 bus DN, and real 95‐bus DN in presence of photovoltaic (PV). The results show that the developed algorithm leads to the better or same accuracy and speed in all comparisons. In addition, results indicated that considering the summation of fundamental and harmonic losses compared to only fundamental losses in DNR can lead to further energy saving in DNs.
... The IEEE 519 brings recommendations about harmonic current limits at PCC. These limits vary according to the short circuit strength of the system [24]. The current THD limits are recommended aiming to preserve the voltage quality at the PCC. ...
This paper investigates a single-phase ac-dc-ac multilevel converter formed by a three-leg module (converter
$a$
) series connected to an H-bridge (converter
$H$
) at the load side of the system to achieve higher and multilevel output voltage. The proposed solution has two dc-links that are connected through a high-frequency link (HFL) formed by an inverter H-bridge, a small toroidal transformer, and a unidirectional rectifier H-bridge. The use of the HFL permits optimizing the SV-PWM strategy by employing vector redundancies that minimize the switching frequency of the devices. Besides, the control system is simplified compared to the conventional solution with floating capacitors. The proposed system is appropriate for uninterrupted power supply and unified power quality conditioner applications. System equations, dc-link voltage specifications, power distribution analysis, and a space vector PWM are discussed. The proposed control strategy ensures suitable load voltage with constant amplitude and fundamental frequency, guaranteeing a high grid power factor and maintaining controlled dc-link voltages. Compared with the conventional solutions, the proposed topology has a lower dc-link voltage rating, lower harmonic content, and lower switching losses in the converters
$a$
and
$H$
. Experimental results are presented to validate the developed studies.
... Отдельные участки распределительной сети 10 кВ, образованные отходящими от ГПП-2 и последующих цеховых РП кабельными линиями, при взаимодействии с индуктивностями сетевых трансформаторов 110/10 кВ и токоограничивающих реакторов в ячейках РУ-10 кВ ГПП-2 создают сложную картину резонансных явлений в частотных характеристиках сети 10 кВ Z СЕТИ (f) относительно секций 1 и 2 РУ-10 кВ ГПП-2 с несколькими экстремумами в области до 10 кГц. В частотной характеристике на секциях РП-19 также присутствуют резонансные явления в высокочастотной области, обусловленные взаимодействием между собственной емкостью и индуктивностью реакторов в ячейках 1, 21 ГПП-2 [13][14][15]. ...
In recent years, the frequency converters (FC) with active rectifiers (AR) have become widespread due to their advantages. The advantages are the possibility of energy recovery in braking modes of electric drive and support of the set value of power factor at the input of AR. At the same time these converters have a significant disadvantage, that is the deterioration of voltage quality in the in-plant 6–35 kV power distribution network due to the imposition of high-frequency harmonics of the input voltage and current of AR on the resonant area of the supply network frequency response. This disadvantage can be eliminated by using special passive filters in the in-plant power networks. They ensure the shift of the main resonance of currents to a zone free from high-frequency harmonics of the FC with AR. It makes possible to reduce the harmonic distortion coefficient in the voltage sections of the main stepdown substation (MSS) of the enterprise. Processing of experimental data is carried out in the Matlab mathematical package with the Simulink application. Using income data of functioning metallurgical complex CherMK of PJSC “Severstal”, the authors carried out the analysis of voltage quality of 10 kV network using specialized passive filters and without them. The article presents the results of the study of the effectiveness of the use of specialized passive filters in the in-plant power supply system of the rolling complex operating at the CherMK of PJSC “Severstal”. The reasons of the deterioration of the voltage quality in the 10 kV distribution network are studied, and as a result, operational breakdown of the modes of sensitive electrical receivers. A complex mathematical model of the 10 kV network has been developed to study the way to improve the harmonic composition of voltage due to installation of specialized passive filters. This filter allows you to adjust the frequency characteristics of the 10 kV network, shift it to an area free of high-frequency harmonics generated by modern frequency converters with active rectifiers. Thus, the resonance of currents and voltages in 10 kV sections is eliminated. As a result, a significant improvement in the shape of the line voltage and a decrease in the harmonic distortion coefficient of voltage THDU = 75,2–91,2 % to values THDU = 0,49–1,4 % is observed. The main result of the research is the recommendation to use a specialized passive filter to eliminate the negative impact of the harmonic component of the current resonance. The research results can be used to design power supply systems of metallurgical enterprises that have powerful electric drives with active rectifiers.
... In addition, note that converter manufacturers often provide the harmonic spectrum data for the FC-AFE currents and voltages only up to harmonics 40-50 for promotion purposes. This can be explained by the limits set by the regulatory standards [47]. On the other side, FC-AFEs generate higher-order harmonics than those set out in standards regulating the power quality. ...
... ). The sources of harmonics n =35,37,47,49,59,61,71, and 73 are the FC-AFEs of the rolling mill electric drives. The resonance of the frequency response of the grid with the impedance at harmonics n = 37, . . . ...
... These distortions can be explained by the overlapping of high-frequency harmonics and the resonant region of the frequency response of the grid(Figure 13b). The sources of harmonics n =35,37,47,49,59,61,71, and 73 are the FC-AFEs of the rolling mill electric drives. The resonance of the frequency response of the grid with the impedance at harmonics n = 37, …, 71 is explained by the mutual influence of the inductances of 380/34.5 kV grid transformers and the total capacity of the cable lines. ...
Today, electric drive systems based on frequency converters with active front-end rectifiers (FC-AFEs) are widespread across industries. In the course of the upgrade of production facilities, such systems replace the conventional converters with thyristor- and diode-based rectifiers. FC-AFEs have the following advantages: the capacity to regenerate the power to the grid and the capacity to operate at the set power factor. The manufacturers of FC-AFEs also claim that their products have the best electromagnetic compatibility (EMC) with the power grid. The best EMC shall be achieved via a multilevel FC-AFE topology and specialized pulse-width modulation (PWM) algorithms for AFE rectifiers. However, the experience of operating mid-voltage high-power electric drives with an FC-AFE in 6–35 kV factory distribution grids with non-linear frequency response due to resonant phenomena refutes the claims of the FC-AFE manufacturers. Resonant phenomena in 6–35 kV grids are caused by the interaction of the inductance of grid components (transformers, reactors) and the capacitance of output cable lines. If the resonance frequency at a sufficient amplitude corresponds to the harmonic frequency of the current consumed by the FC-AFE, the distribution grid will feature high-frequency voltage distortions. This may lead to failures in voltage quality-sensitive electrical consumers. This problem recurred at various metallurgical companies. The purpose of this research is to make a comprehensive overview of the EMC problems during the operation of FC-AFEs at active production facilities, as well as the analysis of the technical solutions aimed at the improvement of the EMC of high-power FC-AFEs with the power grid.
... Figure 5 shows a 3phase power system with non-linear load set up. Table 6 Harmonic voltage limits under IEEE Standard 519-1992 [21] Limits for voltage distortion Figure 6(a) without using a lter, shows the waveform obtained by the Matlab/Simulink simulation model. Since there is a wave ripple that is almost square in shape, the wave form is not totally sinusoidal. ...
... Harmonic current limits according to IEEE Standard 519-1992 (limitations for current distortion in systems rated from 120 V to 69 kV)[21] ...
Harmonics constitutes multiple integrals of the fundamental frequency found in power systems or electric circuitry systems, are primarily caused by non-linear loads that draw current intermittently or have an impedance that changes each cycle of the AC voltage. This can lead to overheating of the system, loss of original waveform, and damage to equipment or system leading to extra expense economically to the consumer. Since harmonics cause distortion in the system and cannot be eliminated from the system, various methods of mitigating to an acceptable level are introduced, use of filters is one of these methods. An STPF adjusted to the 5 th , 7 th , 11 th , 13 th , 17 th , and 19 th harmonic order was employed in this paper in a power system and analyzed. Data was measured on the point of common coupling (PCC) panel using the power quality analyzer tool, and the system was designed on MATLAB/Simulink environment without the filter applied readings were made, and after the STPF was added, both were compared to the IEE 519-1992 standard for which the STPF totally mitigated the harmonics in the system within the standard required.
... Harmonic distortions are caused by nonlinear load's operations (saturated electric machines or rectifers), and they can be minimized by using passive and active flters. To evaluate the power quality of the systems, the two parameters including total harmonic distortion and individual harmonic distortion must satisfy allowable ranges in Table 1 [36,37]. ...
This paper proposes an improved equilibrium optimizer (IEO) for determining optimal location and effective size of distributed generation units (DGUs) in the distribution systems in order to minimize the total power loss on distribution branches, investment cost, and operation and maintenance cost. In a good obtained solution, limits of voltage, current, and harmonic flows are also seriously considered, exactly satisfying predetermined ranges. Especially, individual harmonic distortion (IHD) and total harmonic distortion (THD) of bus voltage must fall into IEEE Std. 519. The proposed IEO is developed from the original equilibrium optimizer (EO), which was motivated by control volume mass balance models. This novel algorithm can effectively expand the search area and avoid the premature convergence to low-quality solution spaces. With the determined solutions from IEO, not only are the voltages well improved but also the harmonics are mitigated from the violated values down to the allowable values of IEEE Std. 519. Moreover, the total power loss is significantly reduced from 0.2110 MW to 0.0815 MW, 0.2245 MW to 0.07197 MW, and 0.3161 MW to 0.1515 MW for IEEE 33-bus, IEEE 69-bus, and IEEE 85-bus radial distribution systems, respectively. Not only that, the total cost of DGUs is also more economical and consumes only $3.4753 million, $3.2840 million, and $3.0593 million corresponding to the three systems for a 20-year planning period. The performance of the proposed algorithm is compared to three other implemented methods consisting of artificial bee colony (ABC) algorithm, salp swarm algorithm (SSA), and EO and eight previously published methods for the three test systems. The comparisons of results imply that IEO is better than other methods in terms of performance, stability, and convergence characteristics.
... As a result, this project can be defined as an attempt to construct a parallel active current harmonic filter, which provides an efficient means of mitigating harmonics, reducing process-related voltage fluctuations, and extending the life of equipment and increasing device power. It can be used as part of a harmonic filtering and power factor correction scheme [5]. ...
Harmonic currents are introduced into power system as use of nonlinear electrical loads increases. Extra losses are caused by harmonic current stream into effective supply lines. A dynamic power filter engenders harmonic compensating current using a switching inverter. Single-phase current into the harmonic filter connects in parallel to load end and inject current harmonic required by the load feeder to avoid harmonic current in the direction of power system. This report discusses harmonic problem, available harmonic mitigation techniques, basic design of filter, control strategy, design steps of major hardware blocks, modelling and simulation of current harmonic filter in MATLAB SIMULINK setting, component selection, hardware implementation and final results. This filter will eliminate harmonic up to 45th order. The control circuit consists of a peak filter, all-pass filter, low pass filter and adders which are used to produce error signal by comparing harmonic current demand of load and injected harmonic current through switching inductor.
