Showing papers on "Total harmonic distortion published in 2022"

Latest Advances of Model Predictive Control in Electrical Drives—Part I: Basic Concepts and Advanced Strategies

Abstract: The application of model predictive control in electrical drives has been studied extensively in the past decade. This article presents what the authors consider the most relevant contributions published in the last years, mainly focusing on three relevant issues: weighting factor calculation when multiple objectives are utilized in the cost function, current/torque harmonic distortion optimization when the power converter switching frequency is reduced, and robustness improvement under parameters uncertainties. Therefore, this article aims to enable readers to have a more precise overview while facilitating their future research work in this exciting area.

Investigation on load harmonic reduction through solar-power utilization in intermittent SSFI using particle swarm, genetic, and modified firefly optimization algorithms

Abstract: A new Symmetric Solar Fed Inverter (SSFI) proposed with a reduced number of components compared to the classical, modified, conventional type of Multilevel Inverter (MLI). The objective of this architecture is to design fifteen-level SSFI, this circuit uses a single switch with minimizing harmonics, and Modulation Index (MI) values. Power Quality (PQ) is developed by using the optimization algorithms like as Particle Swarm Optimization (PSO), Genetic algorithm (GA), Modified Firefly Algorithm (MFA). It’s determined to generate the gating pulse and finding optimum firing angle values calculate as per the input of MPP intelligent controller schemes. The proposed circuit is solar fed inverter used for optimization techniques governed by switching controller approach delivers a major task. The comparison is made for different optimization algorithm has significantly reduced the harmonic content by varying the modulation index and switching angle values. SSFI generates low distortion output uses through without any additional filter component through utilizing MATLAB Simulink software (2020a). The SSFI circuit assist Xilinx Spartan 3-AN Filed Program Gate Array (FPGA) tuned by optimization techniques are presented for the effectiveness of the proposed model.

Design and experimental investigation on VL-MLI intended for half height (H-H) method to improve power quality using modified particle swarm optimization (MPSO) algorithm

Abstract: A Voltage lift performance is an excellent role to DC/DC conversion topology. The Voltage Lift Multilevel Inverter (VL-MLI) topology is suggested with minimal number of components compared to the conventional multilevel inverter (MLI). In this method, the Modified Particle Swarm Optimization (MPSO) conveys a primary task for the VL-MLI using Half Height (H-H) method, it determine the required optimum switching angles to eliminate desired value of harmonics. The simulation circuit for fifteen level output uses single switch voltage-lift inverter fed with resistive and inductive loads (R & L load). The power quality is developed by voltage-lift multilevel inverter with minimized harmonics under the various Modulation Index (MI) while varied from 0.1 up to 1. The circuit is designed in a Field Programmable Gate Array (FPGA), which includes the MPSO rules for fast convergence to reduce the lower order harmonics and finds the best optimum switching angle values. To report this problem the H-H has implemented with MPSO to reduce minimum Total Harmonic Distortion (THD) for simulation circuit using Proteus 7.7 simulink tool. Due to the absence of multiple switches, filter and inductor element exposes for novelty of the proposed system. The comparative analysis has been carried-out with existing optimization and modulation methods.

Direct Modulation Pattern Control for Dual Three-Phase PMSM Drive System

Abstract: The additional harmonic currents in multiphase permanent magnet synchronous motors (PMSMs) have been widely discussed and suppressed by the virtual vectors (VVs). However, the concept of VVs would result in an increasing in the switching frequency and losing the controllability in the harmonic subspace. In this article, a novel direct modulation pattern control (DMPC) method is proposed to provide the further discussion on the lower switching frequency and the better harmonic current suppression. First, a deadbeat control concept is applied to calculate the reference voltage vectors in torque production. In dual three-phase PMSM, there are several switching patterns which could generate the reference voltage vector. The designs of these switching patterns are determined according to the demand. In fact, two design concepts under the structure of DMPC is proposed. One is called the low switching frequency design. The control sets of this design is several switching patterns with only one switching signal. Another is called the low THD design. The control sets of this design is two switching patterns with opposite harmonic voltage vectors. Second, the influence of these different switching patterns in the xy currents is optimized by a cost function. Actually, there are two types of cost function. One is a multiobjective cost function, which is designed to regulate both the amplitude of switching patterns and suppress the xy currents. Another is derived from the first cost function that regulates only the xy currents. The amplitude is determined directly in the voltage vector calculation. Finally, the experimental results show a good performance of these control strategies, in terms of the αβ currents production, the xy currents and the switching frequency reduction.

Experimental investigation and comparative harmonic optimization of AMLI incorporate modified genetic algorithm using for power quality improvement

Abstract: A super-lift mechanism has made tremendous progress in DC/DC conversion technology. In comparison to the asymmetrical form of MLI, the novel Asymmetric Multilevel Inverter (AMLI) technology proposes a minimized number of components. The Fuzzy-PI (Proportional integral) and Modified Genetic Algorithm (MGA) utilizes to minimize the harmonic content considerably using a variety of modulation index and firing angle values in open-loop and closed-loop control. This architecture for designing single-phase 7-level AMLI with an intelligent algorithm proposed for Renewable Energy (RE) applications. This circuit uses a single MOSFET switch with less switching stress and a single DC source. The effectiveness of the proposed MGA optimization eliminates the lower-order harmonics. MGA and Fuzzy-PI based Distributed Power Flow Intelligent Control (DPFIC) algorithms are applied with multilevel structures while maintaining the fundamental frequency for both MATLAB platform and hardware implementation. During this analysis, the losses is also find to investigate the influence of modulation index and output power factor on inverter efficiency. Simulations and experimental findings confirm the proposed inverter capacity to create high-quality multilayer output voltage. However, the proposed closed loop simulation circuit gives 0.47% minimum THD level, and 10.4% in experimental results.

A Modified Multi Level Inverter With Inverted SPWM Control

Abstract: Existing multilevel inverter circuits are constructed by using more number of components and boost operation is not possible. Modified multilevel inverter with step-up operation using fewer components is proposed in this article. The proposed circuit consists of three capacitors and eight switches, which can able to produce seven-level output. Boost operation is based on the charge pump principle, which can boost 1.5 times of the input voltage in the output. Based on this idea, five-level, seven-level, and nine-level topologies are developed in simulink platform, and the outputs are presented in Section IV. A sine pulsewidth modulation (SPWM) is employed to drive switches, and switching pattern is mainly focused to balance the capacitors and to balance capacitor charging/discharging. Among the three proposed circuits, seven-level circuit is discussed in Section II, using mathematical modeling in MATLAB platform and validated in the real-time model. The main aim of this topology is to reduce total harmonic distortion.

Direct Modulation Pattern Control for Dual Three-Phase PMSM Drive System

Abstract: The additional harmonic currents in multiphase permanent magnet synchronous motors (PMSMs) have been widely discussed and suppressed by the virtual vectors (VVs). However, the concept of VVs would result in an increasing in the switching frequency and losing the controllability in the harmonic subspace. In this article, a novel direct modulation pattern control (DMPC) method is proposed to provide the further discussion on the lower switching frequency and the better harmonic current suppression. First, a deadbeat control concept is applied to calculate the reference voltage vectors in torque production. In dual three-phase PMSM, there are several switching patterns which could generate the reference voltage vector. The designs of these switching patterns are determined according to the demand. In fact, two design concepts under the structure of DMPC is proposed. One is called the low switching frequency design. The control sets of this design is several switching patterns with only one switching signal. Another is called the low THD design. The control sets of this design is two switching patterns with opposite harmonic voltage vectors. Second, the influence of these different switching patterns in the xy currents is optimized by a cost function. Actually, there are two types of cost function. One is a multiobjective cost function, which is designed to regulate both the amplitude of switching patterns and suppress the xy currents. Another is derived from the first cost function that regulates only the xy currents. The amplitude is determined directly in the voltage vector calculation. Finally, the experimental results show a good performance of these control strategies, in terms of the αβ currents production, the xy currents and the switching frequency reduction.

Control Strategy of Single-Phase UPQC for Suppressing the Influences of Low-Frequency DC-Link Voltage Ripple

Abstract: The single-phase unified power quality conditioner (UPQC) is widely used to improve power quality for sensitive end-users. However, the inherent instantaneous power difference between parallel and series converter will generate significant low-frequency dc-link voltage ripple and degrade the compensation performance of UPQC. The mechanism of dc-link voltage ripple generation and its influences on compensation voltage and current are analyzed in this article. To suppress the influence, a control strategy is proposed for the single-phase UPQC. For parallel converter, a notch filter is introduced in the outer voltage loop to prevent the voltage ripple entering the control loop, the specific order harmonics compensation is proposed in the inner-current loop to reduce the grid current harmonics. For the series converter, the dc-link voltage feedback is adopted to suppress the influence of voltage ripple on the compensation performance. Simulation and experimental results show that the grid current total harmonic distortion (THD) can be reduced effectively with the fixed dc-link capacitance compared with the traditional control strategy. More than half of the load voltage THD are also decreased by the dc-link voltage feedback control. Moreover, with the smaller dc-link capacitance, single-phase UPQC can maintain the better performance under the proposed control strategy.

High-Efficient Electrolytic-Capacitor-Less Offline LED Driver With Reduced Power Processing

Abstract: In this article, an integrated parallel buck–boost and boost converter (IPB3C) is proposed as an electrolytic-capacitor-less light-emitting diode (LED) driver. The IPB3C provides a high power factor (PF) and low total harmonic distortion (THD). The driver is composed of two converters that are connected in parallel, using just one controlled switch. The buck–boost duty is to deliver constant power to the LED, while ensuring a good PF. The boost converter is employed to cancel the low-frequency ripple at the LED. In return, this decreases the flicker effect and only a relatively small capacitance is needed to fulfill the standard requirements. The buck–boost converter handles the full power of the LED, while the boost converter handles only a portion of the LED power. Thus, better efficiency is ensured by this parallel configuration compared to conventional cascaded integrated converters. Moreover, the voltage across the switch is low, as it is the higher, whether buck–boost or boost converter, but not the addition of both. In this article, the IPB3C is analyzed, and its design methodology is presented. A universal input voltage range prototype of the proposed converter supplying an LED lamp of 108-V/ 0.35-A is presented. The prototype shows high PF, nearly equal to one, very small THD, nearly zero, output voltage ripple of 4.5%, output current ripple of 19%, and high efficiency, equal to 92.4%. Moreover, the converter requires the use of a bulk capacitance of only 68 μF, while the required output capacitance is just 1 μF.

Review of AI applications in harmonic analysis in power systems

Abstract: Harmonics and waveform distortion is a significant power quality problem in modern power systems with high penetration of Renewable Energy Sources (RES). This problem has attracted more attention in recent decades, owing to the increasing integration of power electronic devices and nonlinear loads into power systems. In this paper, Artificial Intelligence (AI) techniques used in different aspects of analyzing harmonics in electrical power networks are reviewed. The tasks of spectrum analysis and waveform estimation or prediction, harmonic source classification, harmonic source location and estimation, determination of harmonic source contributions, harmonic data clustering, filter-based harmonic elimination, and Distributed Generation (DG) hosting capacity in the context of harmonics are considered. The applications of AI in these tasks have been addressed within the literature and are reviewed in this paper. Different AI techniques applied in the study of harmonics such as artificial neural networks, fuzzy systems, support vector machine and decision tree are reviewed. AI techniques mostly outperformed traditional methods in harmonic analysis, particularly under varying operating condition. However, there is still room for improvement regarding the use of combinations of techniques, ensemble learning, optimal structures, training algorithms and further comprehension. This review provides researchers with an insight into research trends in harmonic analysis and outlines opportunities for further research on this increasingly important topic.

Review of AI applications in harmonic analysis in power systems

Abstract: Harmonics and waveform distortion is a significant power quality problem in modern power systems with high penetration of Renewable Energy Sources (RES). This problem has attracted more attention in recent decades, owing to the increasing integration of power electronic devices and nonlinear loads into power systems. In this paper, Artificial Intelligence (AI) techniques used in different aspects of analyzing harmonics in electrical power networks are reviewed. The tasks of spectrum analysis and waveform estimation or prediction, harmonic source classification, harmonic source location and estimation, determination of harmonic source contributions, harmonic data clustering, filter-based harmonic elimination, and Distributed Generation (DG) hosting capacity in the context of harmonics are considered. The applications of AI in these tasks have been addressed within the literature and are reviewed in this paper. Different AI techniques applied in the study of harmonics such as artificial neural networks, fuzzy systems, support vector machine and decision tree are reviewed. AI techniques mostly outperformed traditional methods in harmonic analysis, particularly under varying operating condition. However, there is still room for improvement regarding the use of combinations of techniques, ensemble learning, optimal structures, training algorithms and further comprehension. This review provides researchers with an insight into research trends in harmonic analysis and outlines opportunities for further research on this increasingly important topic.

A Comparative Analysis of Single Phase to Three Phase Power Converter for Input Current THD Reduction

Abstract: In this paper two topologies of single phase to three phase power converters (SPTP) using one single phase rectifier and two single phase rectifiers connected in parallel at front side respectively are discussed. The topology using two single phase rectifiers reduces the switch current, total harmonic distortion in the input supply current and makes the input current nearly in phase with supply voltage. Though the numbers of switches are more in two single phase rectifier topology but the power loss may be lower than the topology using one single phase rectifier. Both the topologies are simulated in MATLAB/SIMULINK and the outputs are compared in terms of THD of input supply current. In both the rectifier PWM controlled technique is used.

Modified CCF Based Shunt Active Power Filter Operation With Dead-Band Elimination for Effective Harmonic and Unbalance Compensation in 3-Phase 3-Wire System

Abstract: The effect of reduction in the terminal voltage of a grid-tied inverter together with minimization in total harmonic distortion (THD) of terminal voltage and current, in the presence of dead-band in the switching remains always challenging for the researchers. With high switching frequency, this issue increases by many folds. The grid-tied inverter used for harmonic compensation acts as a shunt active power filter (SAPF). The implementation of the dead-band elimination technique is based on output current polarity detection, suffers from multiple zero-crossing due to the generation of high frequency switching harmonics during SAPF operation. This paper deals with a dead band elimination methodology together with harmonic compensation using SAPF under non-linear and unbalanced loading conditions. Here, SAPF uses a dual fundamental component extraction (DFCE) scheme with modified complex coefficient filter (MCCF) to extract fundamental components for reference current generation to implement an indirect current control PWM scheme. MCCF extracts fundamental components even in the presence of dc offset and unbalancing at the input. For incorporating dead-band elimination in control, exact polarity detection is done separately through SAPF output current estimation using sensed load current, and modified CCF computed reference source current. Since the estimated SAPF output current contains no high-frequency switching harmonics, the dead-band elimination technique can be correctly implemented. To synchronize the zero-crossing of the estimated and actual SAPF current, an adaptive delay control is used. The proposed MCCF based control logic’s performance together with the dead-band elimination technique is validated for SAPF operating under non-linear, unbalance, and dynamic load conditions. The proposed dead-band elimination scheme based SAPF model is developed and simulated using MATLAB/ SIMULINK. The simulation results show a significant reduction in source current harmonics due to the elimination of odd harmonic injection into the system by incorporating dead-band elimination in SAPF operation. The real-time simulation of the proposed method is also validated using OPAL-RT OP4510 real-time platform.

Performance investigation of modular multilevel inverter topologies for photovoltaic applications with minimal switches

Abstract: Introduction. In recent years, a growing variety of technical applications have necessitated the employment of more powerful equipment. Power electronics and megawatt power levels are required in far too many medium voltage motor drives and utility applications. It is challenging to incorporate a medium voltage grid with only one power semiconductor that has been extensively modified. As a result, in high power and medium voltage settings, multiple power converter structure has been offered as a solution. A multilevel converter has high power ratings while also allowing for the utilization of renewable energy sources. Renewable energy sources such as photovoltaic, wind, and fuel cells may be readily connected to a multilevel inverter topology for enhanced outcomes. The novelty of the proposed work consists of a novel modular inverter structure for solar applications that uses fewer switches. Purpose. The proposed architecture is to decrease the number of switches and Total Harmonic Distortions. There is no need for passive filters, and the proposed design enhances power quality by creating distortion-free sinusoidal output voltage as the level count grows while also lowering power losses. Methods. The proposed topology is implemented with MATLAB / Simulink, using gating pulses and various pulse width modulation methodologies. Moreover, the proposed model also has been validated and compared to the hardware system. Results. Total harmonic distortion, number of power switches, output voltage and number of DC sources are compared with conventional topologies. Practical value. The proposed topology has been very supportive for implementing photovoltaic based multilevel inverter, which is connected to large demand in grid.

Grid Harmonic Current Correction Based on Parallel Three-Phase Shunt Active Power Filter

Abstract: This article presents a finite-set model predictive control (FS-MPC) applied to the shunt active power filters (SAPF) based on three-phase inverters connected in parallel sharing the same dc-link. The discrete-time model of the system is used to predict the future value of the grid, circulation, and offset currents. The presence of circulation and offset currents occurs due to the connection of the two inverters in parallel sharing the same dc-link. There are 64 switching state vectors for SAPF and, in order to reduce the burden of calculation, only 30 switching states are chosen and applied, however keeping the advantages of the FS-MPC algorithm. The control strategy ensures the sinusoidal shape of the grid current, high power factor, and circulating and offset currents suppression. The FS-MPC has its performance compared to the pulsewidth modulation (PWM) strategy considering the SAPF with two parallel inverters, the conventional SAPF and the neutral-point-clamped SAPF. These comparisons include harmonic distortion, power semiconductor losses, and analysis of dc-link capacitor losses. As a multilevel topology, the SAPF with two parallel inverters using FS-MPC present competitive efficiency and can be applied with a good performance in industrial and residential applications. Simulation results and a laboratory-scale experimental platform is used for corroborating the proposal.

Faster Convergence Controller With Distorted Grid Conditions for Photovoltaic Grid Following Inverter System

Abstract: The hysteresis current controller (HCC) for grid following inverter (GFI) system with $LCL$ -filter is a well-known controller for its robustness, fast reference tracking, better dynamics, and easier implementation compared to other controllers. However, HCC behaves differently while integrating such a system with solar photovoltaics (PV). The PV-based GFI system requires fast convergence while transferring maximum power from PV to the grid at minimum converter losses through GFI. This paper therefore proposes a modified double-band HCC (MDBHCC) with proportional resonant (PR) controller for single-phase PV integrated GFI system with LCL-filter. The proposed algorithm implements a unipolar symmetrical PWM strategy for reducing inverter switching losses through a sequential logic with an adaptive clock. It improves the variation in switching frequency and limits the maximum switching frequency of HCC while enhancing the total harmonic distortion (THD) of the injected current into the grid at the point of common coupling. To alleviate the power quality problem and achieve zero steady state error, the proposed MDBHCC with PR control operates at lesser % THD. Simulation and experimental results are presented, with a significant decrease in switching frequency and an improvement in grid current harmonics at both steady-state and dynamic conditions.

PSO-Optimized SHE-PWM Technique in a Cascaded H-Bridge Multilevel Inverter for Variable Output Voltage Applications

Abstract: One of the problems of the selective harmonic elimination pulsewidth modulation (SHE-PWM) method is a limited range of feasible solutions. In many practical applications, the inverter is required to produce a variable output voltage within a wide range (e.g., 0.1 to 1). When the inverter operates in a low modulation index (low output voltage), the output harmonic distortion increases. This article introduces a method to use the SHE-PWM technique for a wide range of modulation indices, which allows achieving a high-quality output waveform in a cascaded H-bridge multilevel inverter. In a five-level case, a dc–dc converter regulates the dc-link voltage of only one bridge. In this way, the extra hardware requirement is reduced, and also a higher number of voltage levels is achieved, which improves the waveform quality. The particle swarm optimization algorithm is used to solve the SHE problem for different output voltage values. Two strategies are proposed to obtain the variable dc-link voltage; one of them is suitable for the lower output voltage values and the other one is more suitable for high values of the output voltage. The proposed strategies have been tested through simulation and experimental studies in different conditions. The results indicate a considerable improvement in the output waveform quality.

Problem of Total Harmonic Distortion Measurement Performed by Smart Energy Meters

Abstract: Abstract Currently, electricity is treated as commodity that should be delivered from a distributor to a consumer with a certain quality. The power quality is defined by the set of measures with specific limit values. One of the basic measures is the Total Harmonic Distortion (THD), which allows to assess the level of the voltage distortion. The measurement of THD ratio should be carried out in accordance with the normative specification. It is assumed that this requirement is met by class A power quality analyzers. Currently, measures are taken to monitor power quality in a large number of measurement points with the use of smart energy meters that are part of the Advanced Metering Infrastructure (AMI). The paper presents the problem of THD ratio measurement by AMI meters if voltage fluctuations occur. In such situation, inconsistency in measurement results of AMI meters and class A power quality analyzers occurs. The problem is presented on the basis of laboratory study results in which disturbances in power grid are recreated.

A 13-Bit ENOB Third-Order Noise-Shaping SAR ADC Employing Hybrid Error Control Structure and LMS-Based Foreground Digital Calibration

Abstract: This article presents a third-order noise-shaping (NS) successive approximation register (SAR) analog-to-digital converter (ADC), which exploits a hybrid error control topology to increase the order of the noise-transfer function (NTF). This scheme is a hybrid of two NS stages, namely, a cascaded integrator feed-forward (CIFF) and an error feedback (EF). This EF-CIFF structure contributes a more effective NS capability and enhances the robustness of the high-order NTF. An improved dither-based digital calibration is developed to mitigate the harmonic distortion caused by the capacitor mismatch. Due to the usage of an averaging filter, this calibration greatly reduces the interference of quantization noise on mismatch extraction while only needing a minimum modification in a standard SAR Topology. Hence, our scheme is simple and inherently robust to the process, voltage, and temperature variation. Based on an 8-bit SAR, our prototype is fabricated in a 130-nm CMOS process. It consumes a 96- $\mu \text{W}$ power when operating at a 2-MS/s sampling frequency with a 1.2-V supply. The proposed NS-SAR yields a peak Schreier figure of merit of 170.7 dB with a signal-to-noise-and-distortion ratio (SNDR) of 79.57 dB at an oversampling ratio of 8.

Grid connected photovoltaic system impression on power quality of low voltage distribution system

Abstract: Abstract To ensure the global energy demands and decarbonize the production of electricity, the expanded utilization of solar photovoltaics (PV) as a renewable energy resource has been increasing in recent decades, principally with the feasibility to be integrated with the conventional power grid. However, supplying clean power from PV grid-connected systems is often hampered by power quality (PQ) disturbances caused by the intermittent nature of solar radiation and other factors related to the grid, converters, and connected loads. To prevent deterioration of the power quality of the system, these disturbances must be mitigated. This paper technically studies some of these PQ issues, that is, the current total harmonic distortion (THD) which causes harmful effects on the whole connected power system and the linked loads. The case study works on a 5.5 kW grid-connected rooftop PV power system established at Benha Faculty of Engineering, Egypt, with the assistance of an installed weather station that boosts the validation of the research results. All aspects regarding the aforementioned small plant are presented including description and simulation of the whole system, review of current THD problems occurring at the point of common coupling (PCC), and a review of other disturbances observed by connected meters. A detailed examination of four techniques for harmonic mitigation, namely the on-off technique, LCL filter, active power filter, and hybrid active power filter is presented with a final comparison to assess the merits and demerits of each one. This research achieved a current harmonic limitation of 1.5%.

Photovoltaic Partial Shading Performance Evaluation With a DSTATCOM Controller

Abstract: A solar photovoltaic distribution static compensator (SPV-DSTATCOM) under partial shading condition (PSC) is studied using a single-stage, 3-phase grid-connected mode. Under PSC, the performance of the grid-connected SPV-DSTATCOM is studied and addressed the issues such as active current sharing, reactive power control, and harmonic elimination. Rejection of DC offset with such PSC condition is an issue when using a conventional Proportional Resonant (PR) controller. As a result of this research, a new and improved PR (IPR) based second-order generalized integrator (SOGI) has been developed that has unity gain at the fundamental frequency and greater DC offset rejection capability to address the PR controller shortcomings. The proposed controller’s performance is evaluated in both steady-state and dynamic conditions with varying loads and different PSC conditions. An experimental evaluation of the proposed controller’s design assumptions is also presented in the form of a comparison with both the PR controller and the adaptive PR controller.

A Single-Phase Five-Level Transformer-Less PV Inverter for Leakage Current Reduction

Abstract: Multilevel inverters are becoming more and more popular in photovoltaic applications because of lower total harmonic distortion, lower switching stress and lower electromagnetic interference. In this article, a single-phase five-level transformer-less PV inverter is proposed for the purpose of leakage current reduction. The inverter is based on a flying capacitor (FC) configuration, the voltages of FCs are balanced at V _dc /4 through the coordination of the two half-bridge at the switching frequency, helps to reduce investment cost in passive elements. Two bidirectional circuits are added to guarantee a constant common-mode (CM) voltage. The leakage current elimination mechanism is analyzed in detail with operational states and CM equivalent model. The losses are analyzed, the control strategy and the FCs are detailed designed. A comparison is also made in terms of the number of elements, voltage stress and CM voltage. Experiment results under grid-connected condition show that the proposed topology achieves both excellent differential-mode and CM performance.

Power Quality Improvement for Vehicle-to-Grid and Grid-to-Vehicle Technology in a Microgrid

Abstract: The demand for electric vehicles continues to grow, as evidenced by global sales of electric vehicles reaching 2.2 million in 2019 and more than doubling to 6.6 million in 2021. The rapid growth of renewable energies and electric vehicles (EVs) necessitates the use of microgrids, which are a promising solution to the problem of integrating large-scale renewables and EVs into the electric power system. Besides, the essential policy support provided by the government is an increase in the availability of public charging infrastructure for EVs. This research employs a fast-charging configuration of an off-board charger with DC energy transfer. Implementation of DC energy transfer for vehicle-to-grid and grid-to-vehicle technology in a microgrid due to DC charging’s unrestricted charger-rated power and rapid power transfer. However, the integration of EVs in the Microgrid system creates some operational challenges, which in this research are power quality issues such as harmonics in power systems that affect both utilities and consumers. The design models using the PI controller and the fuzzy controller based on MATLAB software are simulated to determine the control system’s effectiveness. These simulations assess the control system’s performance, and both approaches help improve the system’s performance power quality by minimizing the system’s total harmonic distortion (THD). According to the results, the fuzzy logic controller exceeded the traditional PI controller as demonstrated by minimizing the THD and also in terms of improving the waveform quality which achieved high accuracy with good performance. This research also utilized the fuzzy logic controller to control the power transfer between EVs and the microgrid, which differs from other research work, to achieve high system efficiency for the benefit of consumers.