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Off-grid wind energy systems play a pivotal role in providing clean and sustainable power to remote areas. However, the intermittent nature of wind and the absence of grid connectivity pose significant challenges to maintaining consistent power quality. The wind energy conversion system plays a central role in tapping renewable energy from wind sources. Operational parameters such as rotor and stator currents, output voltages of rectifiers and converters, and grid phase voltage variations are crucial for stable power generation and grid integration. Additionally, optimizing power conversion output through voltage gain analysis in boost converters is essential. Moreover, ensuring electricity quality via total harmonic distortion reduction in inverters is vital for grid compatibility. Goal. Enhancing the power quality of grid-integrated wind energy conversion systems. Methods. The proposed topology is implemented in MATLAB/Simulink with optimized control strategies for enhancing power quality in off-grid wind energy systems. Results. Control strategies with a grid-connected wind energy conversion system yields substantial improvements in power quality. This includes effectively mitigating voltage fluctuations and harmonics, resulting in smoother operation and reduced disturbances on the grid. Practical value. The proposed topology has proven to be extremely useful for off grid-integrated wind system. References 18, table 1, figures 11. [ABSTRACT FROM AUTHOR]

Introduction. Off-grid wind energy systems play a pivotal role in providing clean and sustainable power to remote areas. However, the intermittent nature of wind and the absence of grid connectivity pose significant challenges to maintaining consistent power quality. The wind energy conversion system plays a central role in tapping renewable energy from wind sources. Operational parameters such as rotor and stator currents, output voltages of rectifiers and converters, and grid phase voltage variations are crucial for stable power generation and grid integration. Additionally, optimizing power conversion output through voltage gain analysis in boost converters is essential. Moreover, ensuring electricity quality via total harmonic distortion reduction in inverters is vital for grid compatibility. Goal. Enhancing the power quality of grid-integrated wind energy conversion systems. Methods. The proposed topology is implemented in MATLAB/Simulink with optimized control strategies for enhancing power quality in off-grid wind energy systems. Results. Control strategies with a grid-connected wind energy conversion system yields substantial improvements in power quality. This includes effectively mitigating voltage fluctuations and harmonics, resulting in smoother operation and reduced disturbances on the grid. Practical value. The proposed topology has proven to be extremely useful for off grid-integrated wind system. References 18, table 1, figures 11.

This research article details the design and implementation of a nonlinear adaptive filtering (NAF) technique using an exponential functional link network (EFLN) for a shunt hybrid active power filter (SHAPF) control to solve the current-associated power quality issues on the utility side at the distribution level of electrical power systems. Separation of the fundamental component from the harmonics, achieving unity power factor operation, reducing the reactive power drawn from the source, balancing the currents during transients, and reduction of total harmonic distortion (THD) of the source current are the issues considered to resolve. The proposed technique solves these issues by generating the sinusoidal reference current and separating the fundamental current from the harmonics. When compared to conventional and existing adaptive filtering techniques such as least mean square (LMS), least mean fourth (LMF), and variable step size LMS (VSS-LMS), the proposed EFLN-NAF method excels in terms of speedy convergence, adaptability in noise-specific environments and reduced steady-state coefficient error. MATLAB/Simulink software is utilized to perform the simulations to examine the suggested strategy for the chosen SHAPF topology both in static and dynamic scenarios. For a 15 kW and 3kVAr requirement of the nonlinear load, simulation results proved that the designed PPF for 2kVAr is able to share the reactive power with the APF, thereby reducing its rating and cost. The proposed method of filtering has been proven to be fast converging with 0.049 s, and the THD in steady state is brought to 1.32 % in steady-state and to 3.77 % during transient conditions, which are under standard limits. A hardware prototype of the experimental setup is constructed at the laboratory scale with OPAL-RT (OP4510) as the controller. With an active and reactive power demand of 1.1 kW and 210VAr, the designed PPF supplies 110 VAr, whereas the rest is supplied by the APF. The practical THD in source current is observed to be 2.081 %, which meets the standards. The results from both simulations and experiments are validated, and the efficacy of the proposed technique in mitigating the aforementioned power quality issues is proved. [Display omitted] • A passive power filter design to share the reactive power requirement in addition to mitigating the predominant harmonics of the 5th and 7th order. • A robust nonlinear adaptive filter implementation based on exponential functional link network (EFLN-NAF) algorithm to the shunt hybrid active power filter (SHAPF) control for reference current generation and fundamental component separation from harmonics. • Solution for current-associated power quality issues such as reducing the reactive power burden, achieving unity power factor operation, and mitigating the harmonics, thereby reducing the source current THD value. • Simulation of the proposed technique for the control of shunt hybrid active power filter and evaluation of the outcomes for resolving the power quality issues in both steady-state and dynamic conditions. • Development of a hardware prototype at a laboratory scale using OPAL-RT (OP4510) real-time simulator as a controller for the proposed technique for the control of SHAPF and evaluation of the outcomes. [ABSTRACT FROM AUTHOR]

With the high proportion of renewable energy sources and power electronic devices accessed in the distribution network, the harmonic pollution problem has become increasingly serious. The traditional centralized harmonic mitigation strategy has difficulty in effectively dealing with these scattered and random harmonics. Therefore, a distributed harmonic mitigation strategy based on the dynamic points incentive of blockchain communities is proposed in this paper. Firstly, a comprehensive voltage sensitivity partitioning method with harmonic weight differentiation is proposed to realize the reasonable partitioning of each control node and controlled node in the distribution network concerning variability in harmonic components and their distribution. Then, a harmonic mitigation strategy based on the dynamic integral excitation of self-learning algorithms is constructed to promote self-organized optimization and active distributed coordinated control of mitigation devices. The strategy ensures that the total harmonic voltage distortion rate of each node meets the requirements by adjusting the partitioned collaboration to realize optimal harmonic mitigation. By setting optimized partitions in different scenarios and conducting simulation verification, the results demonstrate the effectiveness of the strategy in this paper. It stimulates synergy between devices through a dynamic incentive mechanism and significantly reduces the total harmonic voltage distortion rate across various test scenarios, reflecting the adaptability of the harmonic mitigation method presented. [ABSTRACT FROM AUTHOR]

The massive embedding of nonlinear loads in industrial, commercial, and residential applications has created severe power quality problems in modern power distribution systems. Compact Fluorescent Lamps (CFLs), which have been designed to replace Incandescent Lamps (ILs), due to their lower energy consumption and longer lifetime, are among the most used non-linear loads. These electric devices, equipped with ballasts and power electronic converters, inject harmonic currents, reactive powers, and create unbalance in the electrical system. Active filters are widely implemented to overcome these issues and improve power quality. In this sense, a Shunt Active Power Filter (SAPF) is developed in this paper to eliminate the under-wanted harmonics caused by multiple CFLs and ameliorate the global power factor in 3-phase 4-wire systems. The suggested SAPF is connected in parallel with the loads and it consists of three main blocks, the reference current calculation block, the Voltage Source Inverter (VSI), and the VSI control block. The reference currents are calculated following the Synchronous Reference Frame (SRF) theory. Meanwhile, Pulse Width Modulation (PWM) based control is adopted for controlling the switching signals. In order to investigate the efficiency and applicability of the developed 3-phase 4-wire SAPF, different simulations and experimental tests are carried out. The measurements are performed by employing a power analyzer and are analyzed with the Power Pad III software. The obtained results disclosed that the proposed SAPF reduced the Total Harmonic Distortion (THD) of the CFL current from 89.6% to 1.62% and improved the power factor. [ABSTRACT FROM AUTHOR]

Solar energy has been gaining momentum recently, with a focus on maximizing its investment potential due to its reputation as the most sustainable and efficient energy source. This shift towards solar power could potentially reduce the reliance on oil-based fuels in the future. As a result of the integration of photovoltaic (PV) energy sources into the grid, the reliability of power distribution and maintaining its quality in these systems has become increasingly important. The presence of non-linear loads in these grids causes distortion of both voltage and current waves on the grid side, so it is necessary to implement effective reduction techniques to reduce the distortions in these waves. The research contribution is TO introduce the integration of an active filter on the dc side of grid-connected PV systems, along with a control circuit for the filter switches. The control switches were operated using a Sinusoidal Pulse Width Modulation (SPWM) control scheme, while the controller parameters were tuned using the Imperialist Competitive Algorithm (ICA). The proposed system was simulated in the MATLAB/Simulink environment with variations in solar radiation and temperature. The simulation results demonstrated a reduction in the total harmonic distortion factor (THD) for voltage and current waveforms on the grid side, which are within the permissible limits. This confirms the effectiveness of the proposed filter and the efficiency of the control strategy and algorithm for parameter adjustment. [ABSTRACT FROM AUTHOR]

In this research endeavor, a novel approach has been presented to enhance the power quality through a Photovoltaic (PV)-based Dynamic Voltage Restorer (PV-DVR). The proposed work is designed to address voltage fluctuations, flicker, and harmonics within medium or low voltage micro-grid systems. Unlike existing DVR systems that often neglect injected harmonics and converter losses, in the proposed work there is an integration of a PV-fed multilevel inverter system employing Selected Harmonic Elimination and Moderation-based Pulse Width Modulation (SHEAM-PWM). This innovative configuration, coupled with a DC – DC boost converter and a series injection transformer, not only aims to alleviate voltage stress on devices but also optimizes the number of switches to minimize switching losses. The proposed setup successfully reduces the overall voltage Total Harmonic Distortion (THD) to a significant extent, delivering superior dynamic performance. To determine optimal switching angles for the SHEAM-PWM technique, ensuring the elimination or mitigation of the maximum number of harmonics from the output voltage waveform, we employ the Biogeography-Based Optimization (BBO) approach. The computation of these angles is performed offline to eliminate lower-order harmonics, and the results are stored in the microcontroller’s memory using mixed model equations for online applications. The efficacy of our proposed method is demonstrated through both simulation and experimental validation in a real-time laboratory system. The simulation and experimental results obtained underscore the potential utility of our technique for Dynamic Voltage Restorer (DVR) applications, particularly those requiring low harmonic injection. The proposed method introduces a comprehensive and innovative solution for power quality enhancement, combining PV technology, multilevel inverter systems, and advanced optimization techniques. The proposed PV-DVR system exhibits promising results, showcasing its potential for practical implementation in residential micro-grid systems with a focus on minimizing harmonics and ensuring efficient grid compensation. [ABSTRACT FROM AUTHOR]

Industry 4.0 technology is growing rapidly in the manufacturing industry and other businesses. Devices used in Industry 4.0 are manufactured with high-frequency switching functions and generate harmonics that negatively affect power quality. Choosing the direct or parallel connection method of the harmonic current absorber depends on the specific requirements of the system and the goal of improving power quality. Shunt Active Power Filter (SAPF) is the best device currently used to improve power quality. This study proposes to use the fuzzy-rough MARCOS method to make decisions on SAPF selection based on experts’ opinions to improve the quality of power sources at the source of smart manufacturing plants using Industry 4.0 devices. This study implements two decision-making methods in Multi-Criteria Decision-Making (MCDM). The first is the SWARA method (Stepwise Weight Assessment Ratio Analysis), and the second is the MARCOS method (Measurement Alternatives and Ranking According to Compromise Solution). The fuzzy-rough method is used to incorporate uncertain information into the results of decision-making and to use linguistic values. The analysis results of the fuzzy-rough SWARA method show that the price factor and power filter range has the greatest influence on the choice of SAPF for harmonic mitigation. Analysis results from the fuzzy-rough MARCOS method show that manufacturer Schneider Electric has the best features according to the evaluation results from decision makers. Sensitivity analysis methods were used to confirm the findings. The harmonic value THDi displayed in the field after installing the harmonic filter is, respectively, THDi $1=5$ %, THDi $2=6$ %, and THDi $3=5$ %, it meets the regulations of Circular 30/2019/TT-BCT. According to this circular, the requirement for total harmonic value (THDi) is below 12%. With THDi1, THDi2, and THDi3 values all below 12%. In operating electrical systems in production and business environments, using SAPF filters for harmonic mitigation helps improve power quality. The fuzzy-rough method is applied, and the decision maker’s decisions are used to adjust the intention to use the SAPF set to suit the conditions.

The design of a Spotted Hyena Optimization Algorithm-Variable Parameter Tilt Integral Derivative with Filter (SHO-VPTIDF) controller for improved performance and enhanced devaluation of harmonic components of grid-connected photovoltaic systems is the main objective of the suggested manuscript. The SHO-VPTIDF controller is proposed by reformulating Tilt Integral Derivative Controller with Filter (TIDCF). The TIDCF is characterized by longer simulation time, lower robustness, longer settling time, attenuated ability for noise rejection, and limited use. This research gap is addressed by replacing the constant gains of TIDCF by variable parameter tilt integral derivative with filter. The VPTIDF replaces the constant gains of TIDCF with error varying control parameters to improve the robustness of the system. The photovoltaic system with nonlinearities causes power quality issues and occasional faults, which can be detected by using Levenberg-Marquardt Algorithm (LMA) based machine learning technique. The novelties of the proposed manuscript including improved stability, better robustness, upgraded accuracy, better harmonic mitigation ability, and improved ability to handle uncertainties are verified in a Matlab simulink environment. In this manuscript, the SHO-VPTIDF and the Direct and Quadrature Control based Sinusoidal Pulse Width Modulation (DQCSPWM) method are employed for fault classification, harmonic diminishing, stability enhancement, better system performance, better accuracy, improved robustness, and better capabilities to handle system uncertainties.

The design of a Spotted Hyena Optimization Algorithm-Variable Parameter Tilt Integral Derivative with Filter (SHO-VPTIDF) controller for improved performance and enhanced devaluation of harmonic components of grid-connected photovoltaic systems is the main objective of the suggested manuscript. The SHO-VPTIDF controller is proposed by reformulating Tilt Integral Derivative Controller with Filter (TIDCF). The TIDCF is characterized by longer simulation time, lower robustness, longer settling time, attenuated ability for noise rejection, and limited use. This research gap is addressed by replacing the constant gains of TIDCF by variable parameter tilt integral derivative with filter. The VPTIDF replaces the constant gains of TIDCF with error varying control parameters to improve the robustness of the system. The photovoltaic system with nonlinearities causes power quality issues and occasional faults, which can be detected by using Levenberg-Marquardt Algorithm (LMA) based machine learning technique. The novelties of the proposed manuscript including improved stability, better robustness, upgraded accuracy, better harmonic mitigation ability, and improved ability to handle uncertainties are verified in a Matlab simulink environment. In this manuscript, the SHOVPTIDF and the Direct and Quadrature Control based Sinusoidal Pulse Width Modulation (DQCSPWM) method are employed for fault classification, harmonic diminishing, stability enhancement, better system performance, better accuracy, improved robustness, and better capabilities to handle system uncertainties. [ABSTRACT FROM AUTHOR]

This paper presents an improved current control strategy for a three-phase voltage source converter connected to distorted grid. The proposed controller can successfully compensate the induced harmonic currents, while suppressing possible active power ripple. To manage various objectives and deal with tough restrictions, model predictive control can offer a promising solution. However, a modified extended complex Kalman filter is introduced to estimate the positive and negative fundamental components of the grid voltages which are used with the real and reactive power references to generate pure sinusoidal reference currents without the need for a phase-locked loop (PLL), avoiding its challenges under abnormal grid conditions. An improved space vector-based model predictive control (SVM-MPC) is proposed to regulate the real and reactive power components. The main target of this controller is to maintain harmonic free grid currents, even in unbalanced and distorted grid conditions, with enhanced performance in terms of fast dynamic response and good steady-state behavior. The proposed SVM MPC uses Pythagoras theorem to determine duty factors, avoiding trigonometric functions, which improves the computational burden and implementation complexity. In addition, fixed switching frequency can be ensured. Simulation and experimental results are carried out to validate the effectiveness and the practical feasibility of the proposed controller under distorted grid conditions.

The Solid State Transformer (SST) is an advanced power electronics-based key component of the distribution system (SST). This paper presents the application of SST to corporate workspaces and IT environments with nonlinear loads to mitigate harmonics. The three stage SST is designed with rectifier, dual active bridge converter and inverter with suitable converter topologies. The system is controlled with dq-transform based Clarke and inverse Clarke transformation system. The proposed system is designed to eliminate source side current harmonics content by injecting compensating current through inverter. The proposed system is implemented and analyzed for non linear load using MATLAB/ Simulink. The power quality is achieved in terms of improved power factor and decreased % THD to permissible limit.

This research paper investigates the new multilevel connections with minimum number of components as a voltage source inverter (VSI) which is connected in parallel as shunt active power filter (SAPF) for the purpose of the improving power quality and reactive power compensation in power systems. The main contribution of this paper is the design & development of modular structure which is capable of producing a wide range of output levels (9,11,13,15,17,19,21,23,25,27,29 and 31) using Asymmetric PV sources. A comparative study is made with other (27-level) reduced multilevel connection (RMC) topologies suitable for asymmetric input sources from solar photovoltaics (SPV). In addition, the state space analysis and the loss calculations are performed in order to ensure that the inverter is superior to the conventional topologies. The switching angles are determined using Particle Swarm Optimization (PSO) method. The implementation part of RMC is carried out with the selective harmonic elimination (SHE) which mitigates harmonics in the system. MATLAB/Simulink software is used for modelling of the proposed system. An Experimental setup of the proposed multilevel connections is developed and then it is experimentally investigated. A capacity of 3 KWp Solar PV system which feeds the DC input to the developed prototype. On the basis of the research findings, it is possible to draw the conclusion that the proposed inverter topology minimizes the voltage harmonics by 2.56% and current harmonics by 2.33% which enhances power quality, compensates the reactive power, lessens the number of components used by 12 and more cost effective. [ABSTRACT FROM AUTHOR]

The world today is increasingly dependent directly or indirectly on the power system. Ensuring the quality of power supplied to electrical equipment is essential. The national regulatory framework is for harmonic mitigation in the global power system. This paper discusses the relationship between Efficiency (E), Security (S), and Reliability (R) for Electric Power Quality (EPQ). We measure the harmonic mitigation regulations listed in the IEEE 519 standard. To evaluate the proposed E, S, and R constructs and their relationship to EPQ, a multi-planning approach the method of Partial Least Squares- Structural Equation Modeling (PLS-SEM) and Deep Learning Artificial Neural Network (ANN) analysis were performed. In it, deep Learning Artificial Neural Network (ANN) was performed to complement the PLS-SEM findings and higher prediction accuracy. The study shows that the aspects of efficiency (E), security (S), and reliability (R) have a significant relationship with Electric Power Quality (EPQ). Another result of the study indicates that science, technology, engineering and math (STEM) resource conditions have a significant and positive impact on EPQ.

This paper presents an improved current control strategy for a three-phase voltage source converter connected to distorted grid. The proposed controller can successfully compensate the induced harmonic currents, while suppressing possible active power ripple. To manage various objectives and deal with tough restrictions, model predictive control can offer a promising solution. However, a modified extended complex Kalman filter is introduced to estimate the positive and negative fundamental components of the grid voltages which are used with the real and reactive power references to generate pure sinusoidal reference currents without the need for a phase-locked loop (PLL), avoiding its challenges under abnormal grid conditions. An improved space vector-based model predictive control (SVM-MPC) is proposed to regulate the real and reactive power components. The main target of this controller is to maintain harmonic free grid currents, even in unbalanced and distorted grid conditions, with enhanced performance in terms of fast dynamic response and good steady-state behavior. The proposed SVM MPC uses Pythagoras theorem to determine duty factors, avoiding trigonometric functions, which improves the computational burden and implementation complexity. In addition, fixed switching frequency can be ensured. Simulation and experimental results are carried out to validate the effectiveness and the practical feasibility of the proposed controller under distorted grid conditions. [ABSTRACT FROM AUTHOR]

Proper operation of the grid-tie transformerless converters under unbalanced and distorted conditions entails a precise detection of the frequency and fundamental component of the grid voltage. One of the main problems that could arise during the estimation of grid parameters is the existence of a DC offset generated from measurement and A/D conversion. This undesirable induced DC offset could appear as a part of the reference sinusoidal current of grid-tie converters. Although literature has proposed the use of an extended complex Kalman filter (ECKF) for the estimation of positive and negative sequence voltage components as a promising competitor to phase locked loops, mitigating the effect of possible DC offsets when a Kalman filter is employed remains scarce. This paper proposes a new extended complex Kalman filter to improve the filter stability for estimating the frequency and the fundamental positive and negative symmetrical components of the grid voltages, where DC offset, scaling error, and noise can successfully be rejected. The theoretical findings are experimentally validated. [ABSTRACT FROM AUTHOR]

Research on global harmonic mitigation against distributed and high‐proportioned nonlinear loads in modern distribution networks has received extensive attention. In this paper, a distributed compensation method for active power filters (APFs) is proposed, which utilizes a small number of APFs with adjustable reference to alleviate the global voltage distortion caused by a large number of distributed nonlinear loads. The model predictive control (MPC) is employed to calculate the optimal current reference for compensators at each optimization moment by predicting the system's performance in a certain future time period. Furthermore, the Kalman filter (KF) algorithm is used to estimate the initial harmonic voltage for the MPC, reducing the unfavorable effects of the model uncertainty and measurement noise. The test results based on a seven‐bus distribution network in MATLAB are provided to verify the effectiveness of the proposed method. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Shunt Adaptive Power Filter (SAPF) is widely used in the performance of power quality improvement activities in the power supply industry for processing industries or civil power sources in the world today based on its simplicity, transparency, high reliability, efficiency, and reliability, and their powerful compensating current-providing nature. The PI controller integrated into the SAPF operation mechanism works with extra high efficiency in selecting the current to compensate for the lost current generated in the power supply due to harmonics generated by the K p ,   K i parameter values. The system operates by the PWM method for bridge rectifier circuits that perform the function of selecting the appropriate compensating current, providing correct compensation for the amount of current loss in the power supply. Adjusting the K p ,   K i parameter to reach the optimal value by different methods is a promising and popular research direction at present. The K p ,   K i parameter serves the right purpose for the PI controller to generate enough PWM pulses to excite the bridge rectifiers to generate just the right amount of compensating current and enough current to be compensated on the power supply. The commonly used K p ,   K i parameter adjustment methods include the Ziegler Nichols closed-loop vibration method, the P-Q theoretical method, and several other methods. This study conducts a comprehensive review of the literature on modern strategies for adjusting the K p ,   K i parameters in the PI controller in the SAPF suite by using the meta-heuristic optimization method. This study performs classification according to the operation mode of meta-heuristic optimization methods to adjust the K p ,   K i parameter to control the PI to select the correct PWM frequency to activate bridge rectifiers to select the most optimal compensation current to compensate for the loss of current on the power supply to meet the goal of improving power quality in accordance with IEEE 519-2022 standard, leading to the total harmonic distortion (THD) value is below 5%. The study presents in detail some meta-heuristic optimization algorithms, including applications, mathematical equations, and implementation of flow charts for SAPF and provides some open problems for future research. The main objective of this study is to provide an overview of applying meta-heuristic optimization algorithms to the   K p ,   K i parameter tuning of PI controllers. [ABSTRACT FROM AUTHOR]

The Solid State Transformer (SST) is an advanced power electronics-based key component of the distribution system (SST). This paper presents the application of SST to corporate workspaces and IT environments with nonlinear loads to mitigate harmonics. The three stage SST is designed with rectifier, dual active bridge converter and inverter with suitable converter topologies. The system is controlled with dq-transform based Clarke and inverse Clarke transformation system. The proposed system is designed to eliminate source side current harmonics content by injecting compensating current through inverter. The proposed system is implemented and analyzed for non linear load using MATLAB/Simulink. The power quality is achieved in terms of improved power factor and decreased % THD to permissible limit. [ABSTRACT FROM AUTHOR]

The subject of this research is the use of a HAPF to build up power quality during EAF operations in steel production. The HAPF system accomplishes well through simulation and experimental validation, and hence, shows an enviable performance in leveling power quality. Simulation shows that THD become one fifth of the original, which is 15%. Thus, practical wave shaping method is validated. They do not only protect the machines against current surges or overloads but also ensure voltage deviations are limited to ±2V under normal operation and even free up to ±3V over the load conditions to demonstrate the strength of voltage regulation capabilities. HAPF ensures the effective improvement in power factor of 0.85 lagging leading to0.98 leading during normal condition and 0.80 lagging to 0.95 leading under overload condition. Theory matches experimental results emphasizing the possibility of HAPF's actualization and efficiency on the real-world production line. This study facilitates the diffusion of green technologies in the industry, thus, may cause an improvement in energy efficiency, operating stability of power provision and environmental impacts. [ABSTRACT FROM AUTHOR]

In the last two decades, a rapid increase in the utilization of non-linear loads within electrical grids has been observed. Consequently, elevated levels of harmonics are found in both voltage and current waves, and adverse effects on power quality are caused. In this context, the variable speed drive (VSD) systems are considered a significant non-linear contributor. To mitigate the harmonic content in VSD systems, various techniques are explored, such as electronic smoothing inductor incorporation in the DC-link, active filters utilization at the grid side, and passive filters integration. A technique centered on the reconfiguration of the DC-link in the VSD systems is proposed in this paper to improve the overall performance of the VSD systems. The configuration comprises two transistors and two diodes, along with smoothing inductors and a capacitor to enhance power quality in the VSD systems. The utilization of three-stage sine pulse width modulation (SPWM) control technology ensures accurate control of the switches, generating optimal control signals that enhance the power quality of the voltage and current waves at the grid side. The effectiveness of the proposed approach is tested via time-domain simulation in MATLAB/Simulink under both constant and variable loading conditions and is verified using a laboratory prototype. The obtained results demonstrate a notable improvement in power quality, showcasing reduced total harmonic distortion (THD) in AC voltage and current waveforms, as well as minimized ripple factor in the DC-link when compared to existing methods. • Proposing a topology to reconfigure of the DC-link in the VSD systems. • Eliminating the need for any further hardware modifications in system structure. • Improving power quality specifications of the VSD systems by decreasing THD in the grid-side waves. • Designing a laboratory prototype to validate the efficacy of the suggested configurations. [ABSTRACT FROM AUTHOR]

Quality power is a very important factor for the proper functioning of appliances and can be enhanced using shunt active power filters (SAPF). This work demonstrates the hardware implementation of synchronous reference frame (SRF) theory based SAPF. This paper presents the technique of particle swarm optimization (PSO) to tune the gain values of the SAPF PI controller to control the voltage of the DC-link and enhance its dynamic efficiency. The estimation of gain values of PI controllers using conventional methods does not yield the expected outcomes under varying load conditions. The PSO tuned controller provides better results as compared to traditional tuning methods. The switching scheme is implemented using hysteresis controller to control the SAPF. The main objectives of this approach are to extract the compensating currents and cancel out the harmonics produced by balanced, unbalanced and nonlinear loads. The planned scheme is designed and implemented in MATLAB/Simulink and then its performance on a developed laboratory prototype is validated experimentally.

This research work proposes a cost-effective Hybrid Active Harmonic Filter (HAHF) method to mitigate current harmonics in an industrial or commercial power network. The proposed HAHF is based on a Silicon-Controlled Rectifier with an Electronic Inductor (SCR-EI) topology with a reduced number of fully active switches and a better harmonic performance. A new shifted-pulse current modulation method is proposed to cancel harmonics caused by other converters. A Particle Swarm Optimisation (PSO) algorithm is implemented to optimise the modulation parameters and minimise the total harmonics. A lab prototype is implemented in the laboratory to validate the proposed mathematical method and simulation results.

Harmonic pollution sources in microgrids have the characteristics of high penetration and decentralization, as well as forming a full network. Local harmonic mitigation is a traditional harmonic mitigation method, which has the disadvantages of complexity and costly operation. Based on the idea of the decentralized autonomy of power quality, this paper establishes a comprehensive optimization model of the active power and harmonic mitigation capacities of grid-connected inverters based on two-layer optimization and realizes harmonic mitigation. Firstly, based on the harmonic sensitivity analysis, the calculation method of harmonic mitigation capacity is given. Secondly, a two-layer model of harmonic mitigation optimization is established. The upper-layer optimization model takes the minimum operation cost of the microgrid as the objective and the active power reduction in the multi-functional grid-connected inverter (MFGCI) as the optimization variable. The lower-layer optimization model offers the best harmonic mitigation effect as the objective and the harmonic current compensation as the optimization variable. According to the relationship between the total remaining capacity of MFGCI and the capacity required for harmonic mitigation, there are three different objective functions in the lower-layer optimization model. Then, the model solving steps are provided. Finally, an example shows that the proposed optimization model can achieve harmonic mitigation at different times. Compared with the case without active power optimization, the operation cost of the whole system can be reduced by up to 14.6%, while ensuring the harmonic mitigation effect. The proposed method has the advantages of a harmonic mitigation effect and economical system operation. [ABSTRACT FROM AUTHOR]

Due to globalization and industrial development, the need of power is increasing day by day. In addition, due to the high demand for clean energy sources, the use of renewable systems has expanded in recent years. Wind systems can take advantage of the copious and free energy provided by the wind, which is a significant benefit. However, changing incident energy from renewables generate harmonics, which may result in poor system performance. The power quality has therefore become an important issue for both the power suppliers and consumers. Power electronic devices and nonlinear loads have been used frequently in industries hence introducing harmonic distortions in the industrial power distribution network. Harmonics have adverse effects on the power quality like degradation of power generation efficiency, higher operational costs, overheating of equipment, saturation of transformer, electromagnetic interference etc. In order to solve these problems, the implementation of suitable filtration techniques and the evaluation of efficiency with harmonic reduction are crucial. Since, utilities are always aiming to improve the power quality with minimum filtering units, this paper compares the performance of two available filter implementation plan, namely the shunt active power filter (SAPF) and the single tuned filter (STF) in a renewable penetrated industrial distribution network. Based on the outcome of the comparison, a genetic algorithm (GA) based approach is proposed in this paper to determine the optimum size and position of the minimum required filtering units that improves the network’s existing harmonic scenarios. Simulation results to validate the proposed methodology are presented. According to the results, the proposed method of incorporating filtering units significantly outperformed in lowering total harmonic distortion (THD) in an industrial power distribution network with a higher renewable penetration.

Proper operation of the grid-tie transformerless converters under unbalanced and distorted conditions entails a precise detection of the frequency and fundamental component of the grid voltage. One of the main problems that could arise during the estimation of grid parameters is the existence of a DC offset generated from measurement and A/D conversion. This undesirable induced DC offset could appear as a part of the reference sinusoidal current of grid-tie converters. Although literature has proposed the use of an extended complex Kalman filter (ECKF) for the estimation of positive and negative sequence voltage components as a promising competitor to phase locked loops, mitigating the effect of possible DC offsets when a Kalman filter is employed remains scarce. This paper proposes a new extended complex Kalman filter to improve the filter stability for estimating the frequency and the fundamental positive and negative symmetrical components of the grid voltages, where DC offset, scaling error, and noise can successfully be rejected. The theoretical findings are experimentally validated.

With the increased usage of power electronics at the source and load ends of modern power systems, power quality issues like harmonic control and total harmonic distortion (THD) minimization are being given considerable attention. Selective harmonic elimination and mitigation (SHE and SHM) are well-known effective techniques to control the low-order harmonics in the voltage and current waveforms generated by DC–AC converters, which otherwise pollute the grid waveforms and lead to undesired losses. As these methods also result in lower switching losses, they are mostly beneficial for high-power applications like medium-voltage electric drives and grid-connected systems. This work presents an over-the-decade overview of the enhancements in the SHE and SHM pulse width modulation (PWM) techniques of two-level and multilevel DC–AC converters, discussing various problem formulations and the solving methods of the resulting transcendental expressions. The exclusive use of metaheuristic techniques, neural networks, and predictive control structures in expression solving and controller architecture are discussed. The current and future research directions are presented with a focus on optimization, digitalization, real-time implementation, and low-power application avenues. • The manuscript emphasizes the heightened focus on harmonic controls. • SHE and SHM as effective techniques for controlling low-order harmonics. • SHE and SHM techniques reduce switching losses alongside harmonic control. • Highlighting advancements in pulse width modulation techniques. • Showcases the metaheuristic techniques, NNs, and MPC for designing controller architectures. [ABSTRACT FROM AUTHOR]

• Switching control of shunt compensator based on the Joint Logarithmic Hyper Hyperbolic Cosine Adaptive Filter. • Design implementation of the JLHCAF, which possesses the unique characteristics highlighting its smooth cost function, robustness to errors, and stability. • Improvement in the power quality and load balancing in distribution grid connected with linear and nonlinear loads. • Comparison of proposed control algorithm against the existing adaptive controls. When nonlinear loads are introduced to a distribution system, various power quality challenges emerge, such as load unbalance, harmonic distortion, and reactive power mismatch. This study presents a novel solution utilizing a joint logarithmic hyperbolic cosine adaptive filter-operated distribution static compensator to mitigate these issues. The cost function of the adaptive filter is designed to be smooth for minor errors and resilient to significant errors. The proposed control technique computes fundamental active and reactive currents, generating reference signals for the distribution static compensator. A comparative analysis with conventional adaptive control techniques is also conducted. The distribution system undergoes comprehensive testing under various dynamics to ensure compliance with IEEE-519 standards. Real-time simulation-based experiments are employed to showcase the algorithm's performance. [ABSTRACT FROM AUTHOR]

Voltage/frequency (V/f) drive of a three-phase induction motor plays a crucial role in a flour mill for energy saving. Wheat consumption in India is increasing day by day, which reached 105,000 metric ton (MT) in 2021. India's high wheat consumption and production increase flour mills. Thus, energy efficiency in a flour mill is a must in the present situation. Hence, V/f drives are widely used in flour mills. Apart from the advantages of V/f drive, electronic circuits in a drive induce harmonics in a power system. Power quality plays a vital role in a modern power system. Harmonics by V/f drive increase the current consumption, causing increased losses, cable overheating, and motor overheating, which necessitates a filter for harmonic mitigation. In this paper, an artificial neural network controller-based hybrid power filter is proposed for harmonic mitigation. A hybrid power filter (HPF) is presented to overcome the problems and achieve the active and passive power filter's benefits. Harmonic mitigation of the proposed hybrid power filter is compared with the passive and active filter-based drives. This paper analyzes harmonic mitigation for three-phase induction motors with V/f drive installed in a 300-ton/day wheat flour mill's purifier fan. The performance of the suggested system is analyzed under various speeds in the aspects of harmonic mitigation, reduction in current consumption, and energy saving using various filters. The entire system is developed and analyzed using MATLAB/Simulink. Energy saving is increased by around 10.97 kWh per year by HPF by means of reducing harmonics and current consumption compared to an active power filter, while it is increased by around 28.16 kWh/year compared to a passive power filter. Along with the harmonic mitigation, energy saving is also validated for various filters under various speeds. [ABSTRACT FROM AUTHOR]

This work focused on a harmonic mitigating filter and investigated the effect of the harmonic mitigating filter in the textile industry with innovative energy conservation strategies for energy bill reduction, which covers a pathway to climate change mitigation. Here, the effect of the harmonic filter is found out by the systematic energy audit methodology (Preliminary, Detailed and Post-Audit phase). From the energy auditing, it has been found that the textile industry needed a passive harmonic filter for harmonic mitigation. Since, third, fifth, and seventh order of harmonic predominantly exists in the system. The high stability at higher current, known tuning frequency, low cost and low power consumption makes the passive filter to be the best fit for the system. The voltage and current Total Harmonic Distortion Factor (THDF) have been measured using the class ‘A’ power quality and energy analyzer. The harmonic filter’s effect in harmonics mitigation is prominent; 66.45% of the reduction of current harmonics which is achieved after installing the passive filter at the Point of Common Coupling (PCC) of the system. Also, the reduction of harmonics ensures energy conservation through the reduction of additional losses (joule, copper and eddy current losses). The techno-economic analysis with payback period calculation is carried out and reported. Also, the effect of harmonics like mechanical anomalies (temperature rise) is carefully studied using an infrared thermo graphic technique in the textile industry’s motor loads. The energy conservation and their carbon emission reduction are calculated and reported.

As new energies integrated into grid, the harmonics in the grid are more serious, and the Voltage Detection Active Power Filter (VDAPF) has been used as the mitigation equipment to solve the harmonic problems in power electronic distribution network. The global optimization method generally utilizes 15 min to mitigate harmonic which is named long-time-scale, and it is impossible to mitigate harmonic timely. This paper studies a multi-time-scale harmonic mitigation method which adds 5 min prediction to the global optimization method which is named multi-time-scale. The objective is to correct the deviation of harmonic caused by the long-time-scale harmonic prediction error. This paper utilizes MPC to predict the amplitude and phase variation of the harmonics in short time scale, and utilizes distributed VDAPF to optimize harmonic in long time scale. The IEEE 33 nodes system was used as an example to conduct a comparative analysis of mitigation effects in two different harmonic injection scenarios which injected separately 10 and 20%. The results shows that the mitigating effect of the global optimization method is limited under two different harmonic injection scenarios, and it needs to combine with short time scale harmonic prediction information to ensure the effectiveness and rationality of the mitigation results. When the harmonic current fluctuates, there are unqualified voltage distortion nodes in each region, and the voltage distortion rate is larger. But the MPC can change harmonic prediction in a short time, so every harmonic of each VDAPF conductance values is set bigger, and harmonic conductance of the higher harmonics is relatively lower.

Summary: In this research, a novel pulse‐doubling circuit (PDC) is employed to upgrade the 28‐pulse rectifier to the efficient 56‐pulse rectifier. The main objective of this research is to reduce the power kVA rating. In the autotransformer with a 14‐phase polygon structure, the kVA rating is approximately 39.5% of the load power. Since the pulse‐doubling method is utilized, the rectifier with 56 pulses has benefited from a simpler structure. With a comparison to the other rectifiers, the harmonic mitigation is the clearest feature of the proposed rectifier. According to the experimental and theoretical results, in the proposed rectifier with 56 pulses, the input current THD is less than 3%. Finally, the volume and cost of the proposed rectifier with 56 pulses show a notable reduction. In other words, the proposed rectifier is an economical choice for most sectors of the industry. [ABSTRACT FROM AUTHOR]

This article proposes a three-phase three-level cascaded H-bridge (CHB) based shunt active power filter (SAPF) for the management of peak power demand and the mitigation of multiple power quality problems. The proposed topologies are controlled by a sliding-mode control (SMC) for robustness and better dynamic response. The SMC is designed by mathematical modeling of SAPF. The proposed three-level SAPF for the three-wire system is developed by using three H-bridges and three coupling inductors. The same topology can be extended to the four-wire system without using any additional switches. The management of peak power demand of load is achieved by connecting batteries with the dc-link of the H-bridges. The three-wire topology can be used for harmonic mitigation, power factor correction, and compensation of current unbalances. The proposed topology in the four-wire network is required to suppress the neutral current flow in addition to the abovementioned power quality problems. The performances of proposed topologies are verified through MATLAB/ Simulink and validated through the experimental prototype developed in the laboratory. [ABSTRACT FROM AUTHOR]

In this article, a new harmonic mitigation system using double balanced impedance filtering power transformer (DBI-FPT) is proposed for improving the power quality (PQ). Designed for multistage distribution network with severe harmonic pollution, the proposed system enhances multiport filtering performance, mitigates resonance along with reduction of construction and maintenance costs compared to other alternative system. The simplified model of the proposed system is established by combining the short-circuit impedance calculation method and the characteristics of dual-balanced winding. By analyzing the influence of manufacturing errors on the dual-balanced winding in detail, the optimization method for filtering performance is given, which in turn guides the practical application of DBI-FPT effectively. After that, through comprehensively comparative analysis, the multiport harmonic mitigation characteristics, resonance avoidance, and amplification weaken mechanism of the proposed method are revealed. The experimental results validate that the proposed system is suitable for multiterminal PQ improvement and industrial application in multistage regional distribution network. [ABSTRACT FROM AUTHOR]

This paper presents a new single to three phase converter using rotating magnetic field transformer. Conventional transformers have been used in many converters aiming at supplementary improvements and they usually have no critical effect on the conversion technique. In this paper, the conversion technique is based on a special rotating magnetic field transformer in which there are two windings in the primary and six windings on the secondary side. In the proposed converter, first a single-phase voltage source is applied on the primary windings via a switching technique using thyristors to create a rotating magnetic field. Next, the created field induces three phase voltages on the secondary three phase windings. Nevertheless, the created field in the primary side suffers from low frequency harmonics and can be transmitted to the secondary three phase voltages. Hence, design of the secondary windings is modified to mitigate these harmonics. The paper discusses how the harmonics can be mitigated using two sets of three phase windings with appropriate shift. Finally, the proposed converter is modeled using state equations and the simulation results exhibit the effectiveness of the proposed converter. [ABSTRACT FROM AUTHOR]

The increasing use of power electronic devices can deteriorate the power quality by introducing voltage and current harmonics. In islanded microgrids, the presence of nonlinear loads can distort the point of common coupling (PCC) voltage, while the dead-time effect can also bring additional circulating current harmonics among parallel inverters. To simultaneously attenuate the PCC voltage harmonics and suppress the dead-time induced circulating current harmonics, this paper proposes a coordinated control strategy for harmonic mitigation of parallel inverters. The proposed control strategy allows inverter impedances to be properly reshaped at selective harmonic frequencies. As a consequence, the PCC voltage harmonics are filtered by the inverter operating in the harmonic compensation mode (HCM), whereas the dead-time induced circulating current harmonics are suppressed by the inverter operating in the harmonic rejection mode (HRM). Experimental results from an islanded microgrid prototype with two parallel inverters are provided to validate the effectiveness of the proposed control strategy.

Summary: Power inverter plays important and multifaceted roles as an intermediary between renewable energy sources and the grid. One of these important roles is to maintain and improve the quality of power produced by these energy sources under grid different conditions. The purpose of this article is to present a new control scheme that uses the concept of virtual admittance to reduce the injection current harmonics, when the local grid voltage is distorted. The scheme is implemented in the synchronous reference frame (dq) and the method of obtaining the virtual admittance function is simpler and completely different. Although the responsibility for harmonic compensation rests with the virtual admittance, its constituent loop is outside the main control loop of the injection current and uses the local grid voltage feed forwarding. Therefore, an advantage of this method is that it does not interfere with an important issue such as the stability of the inverter control system. Another important issue considered in this article is the possibility of instability of the inverter control system due to the insufficient damping in the inner loop of the low‐pass output filter and also the ability to give the inverter to start it soft. For these purposes, an internal voltage control loop with a Proportional‐Integral‐Derivative controller (PID) and an external current control loop with PI controller are designed in the synchronous reference frame. Finally, in order to validate the proposed control scheme, the simulation results are presented in different conditions. [ABSTRACT FROM AUTHOR]

High-resolution sinusoidal pulsewidth modulation (SPWM) switching is beneficial in order to achieve compact size and fine sinusoidal output of dc–ac converters. In this article, a novel field-programmable gate array (FPGA) based high-definition SPWM (HD-SPWM) architecture is proposed for adopting a scheme of integrating a lower frequency PWM train to a high-frequency SPWM train in order to suppress inverter output harmonics while achieving high resolution output. An optimized FPGA-based two-stage finite-state-machine (FSM) architecture is designed, where the initial stage decides pulsewidths of a lower frequency PWM train based on the premeditated pulsewidth of the high-frequency SPWM train, whereas in the final stage, lower frequency PWM pulsewidths are integrated with the high-frequency SPWM pulsewidths to generate updated pulsewidths of high-frequency SPWM, i.e., HD-SPWM. Moreover, a preformulation mathematical model is established for the calculation of duty-cycle count values of pulse trains to support the online adjustment of modulation index (MI) of the HD-SPWM. The proposed generation has the benefits of harmonic mitigation, online fine adjustment of MI, low-processing time, and requirement of a minor segment of a medium-sized FPGA; thereby, providing a good tradeoff between larger designs and higher performance. Theoretical calculations, characteristics, and design contemplations are specified, and the HD-SPWM generation is demonstrated through experimentation with a Xilinx Spartan-3 FPGA board. [ABSTRACT FROM AUTHOR]

Inaccurate reactive power sharing and voltage distortion at the point of common coupling (PCC) always exist in a parallel inverter system due to feeder impedance mismatches and nonlinear load disturbances. An enhanced inverter control scheme through an output impedance adjustment is proposed to address these issues. Inverter output impedance is regulated considering fundamental and harmonic frequencies, and accurate power sharing and improved PCC voltage quality are realized at the steady state. In addition, the compensation scheme is easily applied in multiple parallel inverters without any prior knowledge of the feeder impedance. Experimental results with three parallel inverters validate the feasibility of the proposed control scheme. [ABSTRACT FROM AUTHOR]

The locations and sizes of plug-in electric vehicle fast-charging stations (PEVFCS) can affect traffic flow in the urban transportation network (TN) and operation indices in the electrical energy distribution network (DN). PEVFCSs are supplied by the DNs, generally using power electronic devices. Thus, PEVFCSs could be used as power line conditioners, especially as active filters (for mitigating harmonic pollutions) and reactive power compensators. Accordingly, this paper proposes a mixed-integer linear programming model taking into account the traffic impacts and power line conditioning capabilities of PEVFCSs to determine optimal locations and sizes of PEVFCSs. Various load profile patterns and the variation of charging demand during the planning horizon are included in this model to consider different operation states of DN and TN. The proposed model is implemented in GAMS and applied to two standard test systems. Numerical results are provided for the case studies and various scenarios. The results confirm the ability and efficiency of the proposed model and its superiority to the existing models. [ABSTRACT FROM AUTHOR]

DC-connected parallel inverter systems are gaining popularity in industrial applications. However, such parallel systems generate excess current ripple (harmonics) at the DC-link due to harmonic interactions between the inverters in addition to the harmonics from the PWM switching. These DC-link harmonics cause the failure of fragile components such as DC-link capacitors. This paper proposes an interleaving scheme to minimize the current harmonics induced in the DC-link of such a system. First, the optimal phase-shift angle for the carrier signal is investigated using the analytical equations, which provides maximum capacitor current ripple cancellation (i.e., at the main switching frequency harmonic component). These optimally phase-shifted switching cycles lead to variations of the output current ripples, which, when summed together at the DC-link, result in the cancellations of the DC-link current ripples. The results show that when the carrier waves of the two inverters are phase-shifted by a 90° angle, the maximum high-frequency harmonic ripple cancellation occurs, which reduces the overall root-mean-square (RMS) value of the DC-capacitor current by almost 50%. The outcome of this proposed solution is a cost-effective DC-harmonics mitigating strategy for the industrial designers to practically configure multi-inverter systems, even when most of the drives are not operating at rated power levels. The experimental and simulation results presented in this paper verify the effectiveness of the proposed carrier-based phase-shifting scheme for two different configurations of common DC connected multi-converter systems.

This paper presents a new single to three phase converter using rotating magnetic field transformer. Conventional transformers have been used in many converters aiming at supplementary improvements and they usually have no critical effect on the conversion technique. In this paper, the conversion technique is based on a special rotating magnetic field transformer in which there are two windings in the primary and six windings on the secondary side. In the proposed converter, first a single-phase voltage source is applied on the primary windings via a switching technique using thyristors to create a rotating magnetic field. Next, the created field induces three phase voltages on the secondary three phase windings. Nevertheless, the created field in the primary side suffers from low frequency harmonics and can be transmitted to the secondary three phase voltages. Hence, design of the secondary windings is modified to mitigate these harmonics. The paper discusses how the harmonics can be mitigated using two sets of three phase windings with appropriate shift. Finally, the proposed converter is modeled using state equations and the simulation results exhibit the effectiveness of the proposed converter.

This paper proposes an improved coordinated control of standalone brushless doubly fed induction generator (BDFIG) supplying nonlinear loads. Due to the existence of nonlinear loads, the voltage at the point of common coupling becomes distorted with a large number of low-order harmonics, which severely degrades the performance of power generation systems. In order to eliminate the included low-order harmonics, a coordinated control method of harmonic mitigation has been presented in this paper for the control of both machine side and load side converters. Then, a weight factor is introduced to the proposed control method for distributing the contribution of harmonic mitigation between the two converters. Comprehensive experimental results on a 30 kVA BDFIG are presented to verify the proposed control method. [ABSTRACT FROM AUTHOR]