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This paper proposes a novel power-factor-correction system for the harmonic suppression of high-power equipment. It connects a PWM (pulse width modulation) rectifier and several uncontrolled diode rectifier units in parallel. The PWM rectifier is not connected to the load, and the power of the IGBT device is lower than that of the traditional PWM rectifier. The diode rectifier unit is connected in parallel without the loop current, which is convenient for expansion. The diode rectifier unit can still work when the IGBT fails, which enables high reliability. When compared to conventional APFs (active power filters), the proposed system only controls the grid current as a sinusoidal wave at the power frequency, without tracking harmonics, which makes the control simpler and the current THD (total harmonic distortion) lower. In this paper, the operating modes of the proposed parallel system are analyzed and the mathematical model of the circuit is derived. In addition, the corresponding control strategy is proposed and the parameters of the LCL are designed. Finally, simulations were carried out to demonstrate the superiority of the proposed parallel system when compared with the traditional APF, and a 60 kW experimental platform was built to demonstrate the feasibility of the proposed scheme. [ABSTRACT FROM AUTHOR]

The series hybrid active power filter (SHAPF) is known as a very effective harmonic filtering model in power systems. Typically, SHAPF is controlled by a control method based either on the harmonic voltage of the load or on the supply harmonic current. However, the above two methods have the disadvantage of requiring the control coefficient much be large enough, which easily causes system instability. Therefore, this paper presents a new control method for SHAPF. It is a combined control method of the supply harmonic current and the source harmonic voltage. The advantage of the proposed method is the ability to reduce the total harmonic distortion of the supply current and voltage applied to the load with a control coefficient that is not too large. A fuzzy-proportional integral controller is designed for the proposed control method to reduce the compensation error in steady state under variable load conditions. Mathematical models and simulation results have demonstrated the effectiveness of the proposed method in reducing the total harmonic distortion of the supply current, voltage applied to the load and minimize the compensation error at steady state. [ABSTRACT FROM AUTHOR]

DC voltage is one of the important parameters of active power filters. Since the series hybrid active power filter does not withstand the fundamental voltage, it cannot absorb energy from the power grid, making it too difficult to control its DC voltage. In order to solve the DC voltage control problem, an improved control method for the series hybrid active power filter with magnetic flux compensation is proposed in this paper. In this improved method, the fundamental magnetic flux compensation coefficient is equal to 1, meeting the condition of fundamental magnetic flux compensation. This improved method does not rely on the precise detection and phase-locking of the fundamental voltage at the port of the series transformer. A phase-fixed active current component is generated directly by the inverter, enabling the active power filter (APF) to absorb active power from the power grid. Consequently, the active power absorbed by the APF from the power grid has a linear relationship with the active current component. Both simulation and experimentation verified the correctness and effectiveness of this proposed method. [ABSTRACT FROM AUTHOR]

The advent of distributed generation has brought with it a plethora of challenges for the nascent power systems that are being deployed on a large scale. Firstly, the majority of power electronic converters connected to the grid are in current source mode, which results in a lack of inertia and an inability to provide effective inertia or achieve damping support during fluctuations in grid frequency. Secondly, the issue of power quality, caused by the presence of harmonics, is becoming increasingly severe. This is particularly problematic in microgrids or systems with high line impedance, where harmonics can be amplified, thereby further compromising the stability of the power system. To address the deficiency in system inertia, numerous scholars are currently utilizing grid-forming (GFM) technology to achieve virtual inertia. In order to address the issue of system harmonics, it is possible to install active power filter (APF) devices at the point of common coupling (PCC), which serve to mitigate the effects of harmonics. This paper puts forth a proposal for the implementation of an APF with virtual inertia, based on PR + RC composite control. This composite control mechanism serves to enhance the harmonic suppression capabilities of the APF. The introduction of a frequency droop enables the capacitor voltage amplitude to be adjusted during fluctuations in system frequency, thereby achieving virtual inertia and providing active support for system frequency. The experimental results demonstrate that this strategy not only reduces the total harmonic distortion (THD) by 13% in comparison to PI control, indicating excellent harmonic suppression performance, but also allows the system to be inert, achieving positive results in suppressing frequency fluctuations during transients. [ABSTRACT FROM AUTHOR]

This article presents an energy system that enhances the quality of electrical energy by injecting photovoltaic (PV) renewable energy into the electrical network in the presence of a polluting load. This system is based on a new control approach known as Zero Direct Power Command (ZDPC). The innovative aspect of the proposed work is the addition of clean energy while simultaneously removing the unsettling harmonics produced by the nonlinear loads provided by distorted voltages. This approach combines a traditional Proportional Integrator (PI) controller for regulating the DC bus voltage with a clever technique (fuzzy logic) for tracking the Maximum Power Point Tracking (MPPT). The current has a harmonic distortion rate of about 1% with unity power factor due to the suppression of undesirable harmonics from the source currents. A PV panel connected in series with a chopper and managed by fuzzy logic via a two-state inverter ensures the injection of PV energy into the electrical network. Software called MATLAB/Simulink is used to model this system. The outcomes demonstrate the reliability and viability of the ZDPC control, which concurrently ensures harmonic current compensation, power factor correction, and the introduction of solar power into the electrical network despite distorted source voltages. [ABSTRACT FROM AUTHOR]

Severe issues such as degradation of power quality and efficiency have surfaced in past few years due to extensive use of power electronic converters for conversion and control in power system. The shunt active power filter (SAPF) has gained attention as a competent solution among researchers. However, most SAPF control schemes render ineffective results under non-ideal supply conditions. A novel single-phase p–q scheme based on high selectivity filter (HSF) for extraction of reference compensation currents is proposed in this paper. A three H-bridges (3HB) voltage source inverter (VSI) topology of SAPF is considered and its dc-link voltage is regulated using an Enhanced Bacterial foraging optimization (BFO) based PI controller. This topology along with the proposed SAPF control scheme can guarantee improved APF performance as each phase of the three-phase four-wire system can be controlled independently. Extensive investigations are carried out using MATLAB/Simulink simulations followed by real-time performance verification in Opal-RT Lab. The effectiveness is assessed in terms of current harmonics, excessive neutral current and current unbalance compensation. The results obtained with proposed scheme when compared with conventional three-phase and single-phase p–q schemes employing low-pass filters (LPF) yield remarkably superior results under ideal, distorted and unbalanced supply and unbalanced loading conditions. [ABSTRACT FROM AUTHOR]

Enhancing power quality (PQ) using the Unified Power Quality Conditioner (UPQC) is the focus of this article's research review. There has been a dramatic increase in the use of non-linear and electronically switched devices in distribution lines and industries, which makes PQ issues important. Distribution Flexible AC Transmission Systems (DFACTSs) are a novel idea developed to improve the performance of the distribution system. One of the DFACTSs is the UPQC. The design of this UPQC aims to resolve various PQ problems, such as voltage sag/swell, single-phase and three-phase failures, voltage flicker, compensation of current/voltage harmonics, reactive power demand of the load, and compensation of unbalanced loads. It is possible to build the UPQC to protect sensitive loads that are located inside the distribution system and to prevent any distortion from coming from the load side. This study presents a comprehensive analysis of the different configurations of UPQC systems for single-phase and three-phase applications. The UPQC is categorized based on factors such as voltage sag compensation, supply system, converter topology, and system configuration. According to its function, topology, and application, many researchers have given the UPQC several various names, like Multi- Converter UPQC (UPQC-MC), Interlined UPQC (UPQC-I), Distributed Generator UPQC (UPQC-DG), Right Shunt UPQC (UPQC-R), etc. This study is meant to provide a detailed overview of the many possible UPQC system formations. [ABSTRACT FROM AUTHOR]

A single-phase series custom power device (Se-CPD), based on model predictive control (MPC), is presented in this paper to compensate for erratic supply voltage conditions such as voltage sag, swell, and harmonics. The control strategy for Se-CPD encapsulates the generation of reference voltage and optimal switching signals for the voltage source inverter (VSI) of the Se-CPD. The reference voltage extraction from the distorted point of common coupling (PCC) voltage is synthesized using a second-order generalized integrator (SOGI) without any phase delay, unlike the case that uses a low-pass filter (LPF). An MPC realizes the generation of optimal switching signals for Se-CPD with its intuitive and straightforward implementation, without any modulation stage, and considers the converter's switching characteristics in the MPC algorithm itself. The simulation results, using MATLAB/Simulink and the real-time simulation results using the OPAL-RT OP4510 real-time simulator, are presented to validate the SOGI-MPC's effectiveness for voltage quality improvement. [ABSTRACT FROM AUTHOR]

This research proposes a novel method that combines Proportional-Integral (PI) control, Artificial Neural Networks (ANNs), and Synchronous Reference Frame (SRF) theory to improve the performance of a three-phase shunt Active Power Filter (APF) under fault situations. The main goal is to reduce power quality problems in electrical grids that are having problems, such harmonics and voltage sags. To precisely manage the APF, the reference frame in which the grid voltages and currents are synchronized is identified using the SRF theory. In order to provide quick and precise correction of voltage and current distortions, the PI controller is integrated to control the APF's compensatory action. The PI controller offers trustworthy control while running normally, but during errors or disruptions, its functionality may suffer. In order to overcome this difficulty, a self-tuning filter in the form of an Artificial Neural Network (ANN) is presented, which may adaptively modify the PI controller's settings under fault situations. To maintain ideal filter performance, the ANN constantly learns from the system's reaction and modifies in real-time. This self-adjusting feature makes sure that even in the event of grid failures, the APF maintains its ability to mitigate problems with power quality. The suggested method effectively reduces harmonics, voltage sags, and other power quality disturbances under both normal and fault circumstances, as shown by the simulation results. In complicated electrical grid systems, the combination of SRF theory, PI control, and ANN-based self-tuning provides a strong way to improve the dependability and effectiveness of three-phase shunt Active Power Filters.

This paper provides a Self-adjustment Interval Type II Neural Network (SAIT2NN) method combined with Super-Twisting sliding mode control (STSMC), aiming at solving the harmonic current problem and improving power quality in an active power filter (APF) system. The designed neural network takes the advantages of the interval type II fuzzy system to improve the learning ability for complex object, thereby dealing with the nonlinear changes caused by the APF system well. At the same time, the neural network adopts a signal classification and selecting mechanism to raise learning speed while minimizing signal loss to ensure correctness. The eigenvalues used to evaluate the fuzzed signal are also part of the system signal, ensuring functionality and reducing structural complexity. In order to achieve a theoretically tight fit, the online learning algorithms of the SAIT2NN are developed from the Lyapunov method. In order to make up for the chattering problem caused by the inherent error of the neural network and delay of the system, STSMC is used as a compensation mechanism to further improve the accuracy. Experimental study and comparisons are provided to prove the effectiveness and superiority of the performance.

Power quality is critical in ensuring the efficient operation of electrical systems, and Unified Power Quality Conditioners with Distributed Generation (UPQC-DG) systems play a vital role in mitigating power quality issues such as voltage sags, swells, harmonics, and flicker. Proportional-integral (PI) control UPQC-DG systems are crucial for maintaining power quality by stabilizing the DC link voltage, which is also essential for the seamless integration of distributed generation into the power grid. Effective PI control ensures minimal voltage fluctuations and rapid response to disturbances, thereby enhancing overall system reliability and efficiency. However, traditional PI tuning methods, like the Ziegler-Nichols (ZN) approach, often fail to provide optimal performance under dynamic conditions in such complex converters. To address these limitations, this paper presents an innovative approach for real-time tuning of PI controllers in UPQC-DG systems using Particle Swarm Optimization (PSO). The primary objective is to dynamically optimize the PI controller parameters to enhance the stability and performance of the DC link voltage under varying operational conditions. The proposed method was validated in a real-time simulation environment using the OPAL-RT 4512 platform. The results demonstrate the PSO-based method's superior ability to reduce steady-state errors and enhance dynamic response as well. This study underscores the potential of PSO for real-time adaptive control, providing a robust solution for maintaining high power quality in UPQC-DG systems and improving the stability and reliability of distributed generation systems.

Due to the increasing use of nonlinear loads in modern power systems, harmonic currents have become a more prominent problem for power quality. Typically, harmonic currents are compensated by using shunt active power filters. Recently, a novel constrained linear state signal shaping model predictive controller has been proposed for shunt active power filter control. However, due to the high computational requirements of online quadratic programming solvers, the real-time implementation of this solution is quite challenging. Therefore, the present work proposes the use of a linear state signal shaping explicit model predictive control formulation, such that the optimizations are done offline. However, the generated offline data introduces a large memory footprint, hindering real-time implementation. To break the curse of dimensionality, a tensor representation is proposed, which can be efficiently compressed via tensor decomposition methods. The proposed approach was tested in simulation and was able to provide good results. Due to the use of efficient tensor decomposition methods, a considerable reduction of the memory requirement could be achieved.

This article presents a new modulation technique called three-dimensional sigma–delta (3D- Σ Δ ) modulation for high-frequency three-leg four-wire voltage source converters (VSCs) that use wide-bandgap (WBG) semiconductors. These WBG devices allow for the use of high switching frequencies with a greater efficiency than silicon devices. The proposed 3D- Σ Δ technique enables operation at a variable switching frequency, resulting in a significant reduction in switching losses compared to classical pulse-width modulation (PWM) techniques. Moreover, the 3D- Σ Δ technique uses a fast-processing 3D quantiser that simplifies implementation and considerably reduces computational costs. The behaviour of the 3D- Σ Δ modulation is analysed using MATLAB/Simulink and PLECS. The experimental results performed on an active power filter that uses silicon carbide (SiC) MOSFETs demonstrate an improvement in converter efficiency compared to the conventional SPWM technique. Additionally, the experimental results show how 3D- Σ Δ allows for the compensation of harmonics and homopolar currents, thereby balancing the electrical grid currents. The experiments also show that the proposed 3D- Σ Δ modulation outperforms an SPWM technique in terms of power quality, since the former achieves a larger reduction in the harmonic content of the power grid. In conclusion, the proposed modulation technique is an attractive option for improving the performance of four-wire converters in active power filter applications. [ABSTRACT FROM AUTHOR]

To improve the dynamic response speed and performance of active power filter controller, and improve the robustness, tracking ability, and disturbance rejection ability of linear active disturbance rejection controller (ADRC), an improved linear ADRC (LADRC) is proposed. First, a new error adjustment total disturbance is introduced into the linear expansion state observer to adjust the total disturbance of the linear expansion state observer. Then, on the premise of system stability, the controller is applied to the voltage outer loop of shunt active power filter (SAPF), and the mathematical model of active power filter is deduced, and it is controlled according to the first-order linear active disturbance rejection controller. Finally, through frequency domain analysis, the stability, noise immunity, and tracking performance of the improved LADRC are analyzed. Using MATLAB and Simulink simulation platform, the current stability and tracking performance of SAPF under improved LADRC control are simulated and verified, and compared with traditional methods. The simulation results show that the waveform fluctuation of A-phase voltage on the grid side of this method is relatively smooth, and the voltage on the grid side is always kept at ±50 V; the voltage curve of SAPF DC side is kept between the actual set values, about 820 V; the waveform fluctuation of A-phase current on the load side is small, which is ±220 A; the harmonic distortion rate is 4%. It is verified that this method has good tracking effect and anti-interference characteristics, which is of great significance to improve the control performance of active power filter. [ABSTRACT FROM AUTHOR]

DC voltage is one of the important parameters of active power filters. Since the series hybrid active power filter does not withstand the fundamental voltage, it cannot absorb energy from the power grid, making it too difficult to control its DC voltage. In order to solve the DC voltage control problem, an improved control method for the series hybrid active power filter with magnetic flux compensation is proposed in this paper. In this improved method, the fundamental magnetic flux compensation coefficient is equal to 1, meeting the condition of fundamental magnetic flux compensation. This improved method does not rely on the precise detection and phase-locking of the fundamental voltage at the port of the series transformer. A phase-fixed active current component is generated directly by the inverter, enabling the active power filter (APF) to absorb active power from the power grid. Consequently, the active power absorbed by the APF from the power grid has a linear relationship with the active current component. Both simulation and experimentation verified the correctness and effectiveness of this proposed method.

Introduction. This article’s subject is a dual function energy system that improves the quality of the electric energy with help of an active power filter and uses a new technique of command named ZDPC (Zero Direct Power Command) on one hand, and on the other hand it injects the photovoltaic (PV) renewable energy to the electrical networks in the presence of non-linear charges. The novelty of the work consists in the subtraction of disturbances resulting from the non-linear charges is provided by an active power filter based on a new ZDPC method. Methods. This strategy combines a classic PI controller for DC bus voltage regulation with a smart method to maximum power point tracking (MPPT) of power based on fuzzy logic. Purpose. The elimination of the undesirable harmonics from the source currents makes the current almost sinusoidal with a harmonic distortion rate close to 1 %. The injection of PV energy into the electrical grid is provided by a PV panel in series with a chopper through a two-state inverter. Results. This system is simulated using MATLAB/Simulink software. The results prove the robustness and feasibility of the ZDPC control which simultaneously guarantees the compensation of harmonic currents, the correction of the power factor and the injection of the solar power into the electrical grid.

With the advance of social science and technology, the wide use of power equipment and devices has brought a lot of harmonic interference to the power system. These harmonic interference has seriously affected the stability and normal operation of the power system. In order to solve the problem of harmonic pollution in power system, from the point of view of signal processing, active power filter is introduced to detect and process current harmonics. An improved ip-iq detection method based on adaptive LMS-LMF is proposed to achieve high-precision and high-efficiency harmonic current detection. And the command current tracking control is realized by combining space voltage vector and hysteresis contrast control method. The simulation results show that the response time of the improved ip-iq method is 0.05 s, the load current distortion rate is 4.31%, and the harmonic current can be detected quickly and accurately. The power factor of the system is basically kept within the range of 0.95-1, which can quickly adapt to the sudden change of load. It remains stable within 0.01 s of sudden change of load, and has good dynamic response ability. Improved ip-iq detection method based on adaptive LMS-LMF and space voltage vector. Under the comprehensive effect of hysteresis contrast control method, active power filter can effectively track the command current, suppress the harmonic current, and improve the power factor of the system. It has important practical value for improving the power quality of the power grid system.

This paper presents capacitor dimensioning to increase a system's power density while the converter performance for the delta-connected cascaded H-bridge (CHB) active power filter (APF) is not impaired. After comparing aluminum electrolytic capacitors with film capacitors, this paper proposes capacitance design requirements for film capacitors. With the help of trigonometric transformation for periodic time-varying variables, including capacitor voltages and branch voltages, the capacitance design requirements can be represented as positive univariate polynomials, the coefficients of which are with regard to the capacitance value. The optimization solver SeDuMi is then applied to determine whether a capacitance value is feasible by checking the positiveness of the polynomials. This research has very appealing theoretical and practical properties: the time-domain analysis capability for periodic variables is improved, therefore, enabling a fast computation and a broad application. Both the simulations and experimental results validate the proposed strategy. Compared with the previous work, the proposed method can result in a lower capacitance value without degrading the performance, which is beneficial for a low-cost and low-volume system. [ABSTRACT FROM AUTHOR]

Introduction. This article’s subject is a dual function energy system that improves the quality of the electric energy with help of an active power filter and uses a new technique of command named ZDPC (Zero Direct Power Command) on one hand, and on the other hand it injects the photovoltaic (PV) renewable energy to the electrical networks in the presence of non-linear charges. The novelty of the work consists in the subtraction of disturbances resulting from the non-linear charges is provided by an active power filter based on a new ZDPC method. Methods. This strategy combines a classic PI controller for DC bus voltage regulation with a smart method to maximum power point tracking (MPPT) of power based on fuzzy logic. Purpose. The elimination of the undesirable harmonics from the source currents makes the current almost sinusoidal with a harmonic distortion rate close to 1 %. The injection of PV energy into the electrical grid is provided by a PV panel in series with a chopper through a two-state inverter. Results. This system is simulated using MATLAB/Simulink software. The results prove the robustness and feasibility of the ZDPC control which simultaneously guarantees the compensation of harmonic currents, the correction of the power factor and the injection of the solar powerinto the electrical grid. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Guangdong University of Technology is the property of Journal of Guangdong University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Active power filter (APF) can significantly compensate the current harmonics produced by nonlinear loads. To do this feature, harmonic detection beside harmonic generation play vital role. Direct power controller (DPC) has great harmony with instantaneous power compensation (PQ) algorithm as well as ability to eliminate internal current loops. In addition, deadbeat controller (DBC) has high compatibility for digital implementation, superior control performance and fast dynamic response. However, DBC suffers from time delay regarded to control action calculation and digital implementation. In this paper, a new deadbeat-based DPC method is proposed firstly to control and generates the harmonic currents of APF. Several simulations achieved in MATLAB/SIMULINK beside different experimental tests obtained from a DSP-based active power filter are conducted to illustrate and prove the effectiveness and superior performance of the proposed control system. As a result, the THD of grid current decreases from 22% to 3.2% under steady state where dynamic response under with/without compensation validate significant transient response lower than 5ms.

Due to the nonlinear behavior of grid-connected cascaded multilevel inverters (GCCMI), the use of nonlinear controllers can guarantee system stability over a wide range of operation. Therefore, state-space modeling is required to design nonlinear controllers. In this manuscript, a comprehensive method is proposed for the general state-space modeling of an n-level GCCMI with LCL coupling. To validate the accuracy of obtained state-space model, an experimental setup of a cascaded multilevel inverter including two H-bridges has been implemented. The outputs of the state-space model are compared with the simulation and experimental results of the GCCMI. This shows that the proposed model is compatible with a real closed-loop system. The simulations were performed using EMTDC/PSCAD software. In the following, the designed general model is used to develop a nonlinear controller based on the Lyapunov stability criteria for a multilevel shunt active power filter (SAPF). Results show that the designed controller is stable and robust in a wide range of operating point changes. [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]

This paper proposes a current-controlled hybrid power filter (CCHPF) to compensate source current harmonics produced by battery charger. Current harmonics are compensated by the voltage- and current-controlled active power filter, whereas in the proposed system, current-controlled hybrid power filter is used. CCHPF overcomes the limitation of voltage-controlled harmonic compensator, conventional proportional integral controller and the passive filter which has high power loss and which may deteriorate the system frequency with high harmonic attenuation. In the proposed control system, the super twisting sliding mode algorithm (STSMA) is used with a modified form of active power theory and cognitive emotional controller to compute the three-phase compensating current reference and the DC link current regulation. The compensated reference signal obtained by sliding mode controller is used to generate switching pulses to current-controlled active power filter (CCAPF) switches. The significant contribution of the proposed system includes the development of CCHPF and its control strategy based on PI- and emotional controller-tuned STSMA to reduce the harmonic distortion of the source current used in electric vehicle charging. The passive power filter is designed to eliminate fifth-order harmonic current. A major advantage of the super twisting sliding mode control algorithm is its adaptability and robustness, which will result in improved reference current tracking without causing chattering. CCHPF is widely used for compensating harmonics generated by electric vehicle battery chargers, UPS systems and industrial loads. The control technique is implemented in MATLAB Simulink environment for dynamic load conditions, and the obtained result compensates the harmonic current to a required level (total harmonic distortion of source current is 0.79%) satisfying IEEE 519-1992 standard. [ABSTRACT FROM AUTHOR]

Various residential loads such as inductors, capacitors, transformers, rectifiers, uninterruptible power supplies, electrical machines and fluorescent lights result in power factor deterioration and harmonics. Reactive loads linked to the electrical power systems produce reactive power, which declines the current/power quality and power factor in the main network. Therefore, adequate reactive power is required to provide a stable and reliable electric grid. In this paper, an improved control method is proposed to eliminate harmonic effects of different loads, to provide reactive power compensation and effective reactive power flow with a three-phase shunt active power filter (SAPF). The performance results of the proposed control method is examined and compared with the conventional control under comprehensive case studies such as resistive-capacitive linear load (R-CLL), resistive-inductive linear load (R-ILL), non-linear load (NLL) and highly inductive NLL. With the proposed control method, the SAPF supplies adequate reactive power without being drawn power from the main grid to provide a high power factor. Various case studies indicate that the proposed control method can decrease phase discrepancy between grid current and voltage as well as reduce grid current harmonics. Under the impact of different load groups, approximately 0.99 power factor values have been obtained by the proposed control method, while lower power factor values such as 0.79 and 0.81 have been obtained by the conventional control method. In addition, with the proposed control method, the effect of different harmonic loads has been eliminated and the THB of current harmonics has been reduced below 1.0%. [ABSTRACT FROM AUTHOR]

This article presents application of generalized robust logarithmic family (GRLF) framework derived least absolute difference (LAD) Algorithm implemented for active power filters (APF) for PQ enhancement. The presented GRLF-LAD algorithm successfully eliminates lower as well as higher order errors from the harmonically rich nonlinear load currents and thus results in accurate fundamental component extraction. Weak power grids are characterised by distorted grid voltages and riddled with inherent harmonics. Conventional techniques such as synchronous reference frame (SRF) algorithm are unable to filter out the harmonics from grid voltages and this results in oscillations in D-Q components. This leads to generation of a distorted reference current and thus unsatisfactory APF performance. In this article, the grid voltages are processed by modified second-order generalized integrator with quadrature signal generator (QSG-SOGI) based algorithm. The harmonic rejection capabilty of QSG-SOGI is far superior than other tested algorithms. QSG-SOGI shows remarkable improvement of approximately 99.35% than SRF and 96.02% than SOGI in terms of percentage improvement. The performance of presented APF is verified experimentally on a developed prototype and tested rigorously against load variations, grid voltage variations as well as grid distortions. The GRLF-LAD algorithm is found to be approximately 36.04% faster than APA and about 45.16% faster than LMS in terms of dynamic response and about 11.19% better than LMS in accurate current component extraction. The total harmonic distortion (THD) content of presented algorithm is found to be well within the IEEE-519 std.

This paper introduces a novel non-integral method for calculating AC capacitor voltage in shunt hybrid active power filters (SHAPFs). These filters commonly use passive power filters (PPFs) that can introduce voltage containing harmonics into the AC capacitor, leading to overvoltage situations that can be dangerous. To avoid accidents due to overvoltage, it is necessary to monitor the AC capacitor voltage continuously. The proposed method enables the calculation of the voltage across the AC capacitor, using only the sensor available in the SHAPF, without requiring additional sensors. By avoiding the use of integration to calculate the voltage, the method effectively mitigates errors due to DC offset inflows. The effectiveness of the proposed method was verified through simulations and actual experiments. Results demonstrate that the proposed voltage calculation method improves the voltage calculation accuracy by approximately 1.93[%] when compared to the general voltage calculation method. The proposed non-integral AC capacitor voltage calculation method represents a significant advancement for SHAPFs, providing an effective means for reducing overvoltage risks, without requiring additional sensors or costly equipment.

This study presents a method for monitoring the voltage across the AC capacitor in a grid-connected hybrid active power filter without the use of additional voltage sensors. In the case of an AC capacitor used in a hybrid, active power filter, there is a risk of burnout caused by exceeding the allowable voltage owing to the harmonic current and voltage generated by the inverter. Therefore, this study presents a method to monitor the voltage of the AC capacitor using the current from which the DC component has been removed without any additional voltage sensors to prevent the burn-out of the AC capacitor. The proposed sensorless AC capacitor voltage monitoring method is verified through simulations and experiments. The difference between the magnitude of the voltage measured in the simulations and experiments and the magnitude of the voltage predicted with the proposed method was approximately 0.526[%] on average.

The interleaved inverter with simple structure, low output ripple, and flexible expansion has been widely used. A current control method for an interleaved active power filter (APF) with SiC-MOSFETs was proposed, which can compensate harmonic accurately with low output switching ripple. A mathematical model of a two-level interleaved inverter with two-module parallel was discussed. According to the mathematical model of the interleaved topology, a composite current controller with the fast repetitive control (FRC) as the outer loop and the PI controller as the inner loop is designed. The control method proposed is implemented on a 380V/75 A APF with a switching frequency of 50 kHz. In the experiments, The THD of grid current drops from 30.0% to 4.1%, and the time of dynamic full response is 10 ms that is half of the grid period, which verifies the feasibility of the interleaved APF and its control method.

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The case study focuses on the improvement of current harmonics and reactive power compensation methods in the Roşiuţa quarry, part of the Motru Mining Basin of the Oltenia Energy Complex, proposing a method based on the calculation of the instantaneous active power of the grid, with results similar to the conventional method based on reactive power and zero sequence, using the Generalized Theory of Instantaneous Power and demonstrating that it is not necessary to change the reference coordinate system. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper provides a multi-feedback feature selection fuzzy neural network (MFFSFNN) based on super-twisting sliding mode control (STSMC), aiming at compensating for current distortion and solving the harmonic current problem in an active power filter (APF) system. A feature selection layer is added to an output feedback neural network to attach the characteristics of signal filtering to the neural network. MFFSFNN, with the designed feedback loops and hidden layer, has the advantages of signal judging, filtering, and feedback. Signal filtering can choose valuable signals to deal with lumped uncertainties, and signal feedback can expand the learning dimension to improve the approximation accuracy. The STSMC, as a compensator with adaptive gains, helps to stabilize the compensation current. An experimental study is implemented to prove the effectiveness and superiority of the proposed controller. [ABSTRACT FROM AUTHOR]

A sliding mode control (SMC) strategy with a fractional-order scheme is developed to provide an effective way to compensate for the harmonic current and strengthen the performance of an active power filter (APF). The formulation of a fractional-order sliding mode controller (FOSMC) is incorporated in the current control of an APF control system, obtaining an extra degree of freedom over integer-order ones to improve the dynamic property. The simulation results of the APF utilizing the designed strategy confirm the satisfactory performance and smaller total harmonic distortion (THD) by comparative study. [ABSTRACT FROM AUTHOR]

Utilization of active power filters (APFs) is the most efficient method to reduce harmonic pollution in distribution networks. Previous approaches utilized APFs in integrated control schemes based on broad data-gathering systems. Since a broad data-gathering system is not available in most practical distribution networks, previously proposed approaches may not readily be implemented. This paper presents the utilization of stand-alone controlled APFs (SACAPFs) in radial distribution networks. Utilizing APFs with a stand-alone control system decreases implementation costs and complexity by making them autonomous and independent of integrated control systems, which are complicated and expensive in practical applications. In this paper, a single SACAPF is modeled as a dependent current source where its injection current is equal in amplitude but opposite in phase compared to the harmonic content of the current passing through the point of common coupling (reference current). Due to the presence of both linear and nonlinear loads in the distribution network, the reference current changes after injection by SACAPF, so it is necessary to modify the injection current until reaching a constant value in the reference current. This is considered via an iterative procedure in the modeling scheme. Operation of multiple SACAPFs is handled using a backward procedure based on a priority list. Simulation results on an IEEE 18-bus test system show the proper operation of the stand-alone control systems for both single and multiple SACAPF implementation. Furthermore, optimal allocation of the proposed SACAPFs is performed in an IEEE 33-bus test network and a 9-bus test network, and the results are discussed and compared with the allocation of integrated control system APFs. [ABSTRACT FROM AUTHOR]