Control Of Shunt Active Power Filter Research Articles

Analysis of the Influence of the 6-Pulse Thyristor-Bridge Input Reactor Size on the Shunt Active Power Filter Work Efficiency: A Case Study

This paper presents a case study in which the influence of the 6-pulse thyristor-bridge input reactor size on the shunt active power filter (SAPF)’s work performance is investigated. The purpose of using an SAPF in the power system is in most cases for fundamental harmonic reactive power compensation, harmonics and asymmetry mitigation. The work efficiency of such a filter depends not only on the designed control system, interface filter and dc-link capacitor parameters, but also on the parameters of the electrical system in which it is connected. Therefore, it is necessary to study and know the power system (supplier and consumer sides) before its installation. For instance, in the electrical system with diode or thyristor-bridge as loads, the SAPF performance efficiency may not be satisfied due to the high rate of current change (di/dt) at the points of commutation notches. In this paper, the performed simulation and laboratory experiments show that for a better operating efficiency of the SAPF, the input reactor parameters should be selected based not only on the effective reduction in the inverter switching ripple or the control system demand, but also on the parameters of the load, such as the parameters of the diode or thyristor-bridge input reactor. Apart from the experimental demonstrations on how the input reactor size influences the SAPF work efficiency, the novelties in this paper are: the formulated recommendations on how to choose the SAPF input reactor parameters (the SAPF is more efficient in terms of harmonics, asymmetry and reactive power mitigation when the inductance of its input reactor (L-filter) is smaller than the one of the diode or thyristor-bridge input reactor); the proposed SAPF control system; the proposed expressions to compute the SAPF input reactor inductance, DC voltage and capacitor.

Simulation and real time implementation of shunt active power filter for power quality enhancement using adaptive neural network topology

With the rise in non-linear loads, the need for a veracious power filter to alleviate voltage and current harmonics for meeting power quality has been a challenging requirement of the existing power system. This paper presents a systematic approach to improve power quality with a shunt active power filter (SAPF). The controller consists of a neural network approach to enhance the switching control of SAPF under dynamic and non-linear loading conditions. DC link voltage has been regulated using proportional-Integral (PI) control. To extract reference current, instantaneous-reactive power (IRP) theory has been used. IRP theory employing indirect current control strategy provides reference source current signals as well as regulated PWM switching signals for hysteresis control. An ADALINE network has been devised to extract fundamental signals from the polluted supply voltage. The model has been simulated on the MATLAB®/Simulink platform and validated by SAPF prototype in the laboratory using the TMS320F28335 floating-point DSP controller.

Instrumentation for Verification of Shunt Active Power Filter Algorithms.

This article presents a comprehensive system for testing and verifying shunt active power filter control methods. The aim of this experimental platform is to provide tools to a user to objectively compare the individual control methods. The functionality of the system was verified on a hardware platform using least mean squares and recursive least squares algorithms. In the experiments, an average relative suppression of the total harmonic distortion of 22% was achieved. This article describes the principle of the shunt active power filter, the used experimental platform of the controlled current injection source, its control system based on virtual instrumentation and control software and ends with experimental verification. The discussion of the paper outlines the extension of the experimental platform with the cRIO RTOS control system to reduce the latency of reference current generation and further planned research including motivation.

Improving Photovoltaic Grid Integration under Partial Shading by Equilibrium Slime Mould Optimization

In the realm of photovoltaic grid integration with Shunt Active Power Filters operating under partial shading conditions, this study introduces an innovative approach aimed at minimizing both power consumption from the electrical grid and associated costs. The primary objective of this research is to maximize the efficiency of photovoltaic system output by implementing a novel algorithm known as the Equilibrium Slime Mould Optimization technique. This algorithm is employed to precisely track the global power point of the photovoltaic array under partial shading conditions, resulting in increased photovoltaic power injection and decreased grid-side consumption. The choice of the Equilibrium Slime Mould Optimization technique is motivated by its exceptional ability to efficiently explore the search space and avoid falling into local extrema. Additionally, this article incorporates Predictive Direct Power Control, one of the most contemporary Shunt Active Power Filter control techniques, to effectively eliminate harmonics and enhance overall system efficiency. To validate this proposed approach, a simulation setup was meticulously developed. The obtained results demonstrate a remarkable enhancement in the efficiency of photovoltaic power injection compared to the conventional sliding mode technique, which tends to get trapped at local maximum power point, thereby resulting in diminished power injection. This pioneering approach heralds a new era in the application of metaheuristic algorithms within practical systems, leading to enhanced productivity and reduced costs for consumers. Furthermore, it holds the potential to advance various categories of interconnected photovoltaic systems, ensuring improved performance across diverse operational scenarios.

Power quality enhancement using a novel SAPF control scheme employing high selectivity filter

Abstract 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.

Multi-resonant Controller Design for a PV-Fed Multifunctional Grid-Connected Inverter in Presence of Unbalanced and Nonlinear Load

The use of Active Power Filters (APFs) in future power grids with high penetration of nonlinear loads is unavoidable. Voltage Source Inverters (VSIs) interfacing Photovoltaic (PV) generator could play the APF role in addition to power supply. In this paper, the control of a PV-fed multifunctional grid-connected three-phase VSI is addressed with nonlinear and unbalanced load. The control objective is threefold. The first one is to deliver the maximum available power from the PV source to the grid satisfying power quality standards. The second one is the Voltage Balancing Control for DC-link capacitors to guarantee correct operation of the VSI. The last one is shunt APF control to compensate for nonlinear and unbalanced load harmonics, reactive power, and unbalanced sequences. A quasi-Proportional-Resonant (PR) controller with harmonic compensators is proposed for the current control loop. The quasi-PR controller parameters are determined through optimization algorithms such as Particle Swarm Optimization (PSO), Genetic Algorithm (GA), and a combination of both PSO and GA. The aim of the objective function is to improve static and dynamic behavior. The different gains at the fundamental resonant frequency and the selected odd harmonics are obtained for the proposed quasi-PR controller. The dynamic characteristics of the optimized quasi-PR controllers show superiority against conventional ones in terms of gain margin, phase margin, overshoot, and robustness. With the proposed control scheme, the harmonics, reactive power, and unbalanced sequences are appropriately compensated. The performance of the PV-fed VSI shunt APF under irradiance change, load change, and distorted grid voltage conditions is validated through numerical simulations performed on hbox {PSIM}^{copyright } software. The results show that the grid currents Total Harmonic Distortion for irradiance change case study are 4.57%, 4.57%, and 3.22% in phase a, b, and c with the proposed control method, while they are 9.25%, 5.65%, and 10.12% with conventional instantaneous p-q theory.

Synchronization control techniques for shunt active power filter: an overview

The phase synchronization control technique of shunt active power filter (SAPF) is discussed in this article. Due to the harmful effects of harmonic currents on power systems, the issue of decreasing their effects has generated a lot of research. A SAPF is acknowledged as the most dependable instrument in this area. The SAPF will detects the current harmonics present in the power system and also generates and injects the corrective current mitigation in the power system to reduce the current harmonics. This implies that, aside from the capacity to create compensating current, it is more essential to ensure that the SAPF can work in phase with the operational power system so that the compensating current will properly injected. As a result, while constructing SAPF control algorithms, correct synchronisation techniques must be incorporated. In this article, the different types of phase synchronization approach have been discussed such as phase-locked loop (PLL), adaptive linear neuron (Adaline), and unit vector. The results of the study may be used as a guideline and source of information for determining the best method for synchronising SAPF with the associated power system.

Enhanced FPGA-Based Controller for Three Phase Shunt Active Power Filter

Abstract In this paper, a three-phase shunt active power filter (SAPF) controller with a fully digital implementation is presented. The main goal of this contribution is to implement a digital direct power control (DDPC) algorithm without phase-locked-loop (PLL) for SAPF. This algorithm is intended for power quality improvement and current harmonic elimination. The controller introduced in this paper is cost-effective, has a fast-dynamic response, and has a simple hardware implementation. In order to comply with the above specifications, a dedicated controller has been conceived and fully implemented within a field-programmable gate array (FPGA) device. This FPGA-based controller integrates the whole signal-processing functions needed to drive the SAPF, as well as an original method for sector identification. The intended controller provides the desired power references to select the optimal switching sequences. The switching orders follow the grid reference to drive the voltage source inverter (VSI), so the SAPF achieves good performances while ensuring balanced overall supply currents, unity power factor, and reduced harmonic load currents. The proposed digital implementation achieves a valuable compromise between fast dynamic response, minimum execution time, and reduced FPGA resources, through a simple hardware design implementation. The entire system is developed and simulated using VHDL and VHDL-AMS languages.

Shunt active power filter voltage sensorless method using a PR controller for unbalanced grid conditions

Unbalanced issues and power quality problems can be handled using shunt active power filters (APFs). Under weak grid conditions and unbalanced grid impedance, the unbalanced three-phase load leads to unbalanced grid currents and point-of-common-coupling voltages. As a result, there will be a significant fluctuation in the real and reactive power of the grid. Several shunt APF control methods were used to solve unbalanced problems. Both voltages and currents measurements are required in the control method. Proposed in this article is a new voltage sensorless control method of shunt APF by using current measurements only. The reference current of the controller was determined from the positive-sequence component of the measured load currents. The APF was controlled by a PR controller. The proposed approach can eliminate fluctuation in the real and reactive power and balance point-of-common-coupling voltages and grid currents. Simulation and hardware experiments were used to verify the proposed method’s performance.

Power quality enhancement for charging station with moving window min–max algorithm based shunt active power filter

The widespread development of charging infrastructure is essential for the projected growth of electric vehicles. These charging stations are non-linear loads and necessitate shunt active power filters (SAPFs) to prevent the propagation of current distortions into the grid. Otherwise, the system efficiency and power transfer capability would reduce. This paper proposes control of SAPF with a moving window min–max (MWM) algorithm-based computation of the fundamental active component (FAC) of load current. The proposed algorithm computes FAC as the average of the maximum and minimum value of d-axis current over the period corresponding to its lowest order harmonic. The lowest harmonic is six and two for the balanced and unbalanced loading, respectively. Based on whether the currents are balanced or not, the MWM algorithm determines the width of the moving window where the minimum and maximum values are stored for computing FAC. The computational simplicity of this algorithm is evident from the pseudo-code presented. The experimental results show that the proposed method offers faster dynamic and accurate steady-state responses than the low pass filter-based synchronous reference frame method. Furthermore, analysis of SAPF operation with the proposed extraction scheme based on simulations reveals that the charging station operation complies with the power quality standards.

Review of Fundamental Active Current Extraction Techniques for SAPF.

The field of advanced digital signal processing methods is one of the fastest developing scientific and technical disciplines, and is important in the field of Shunt Active Power Filter control methods. Shunt active power filters are highly desirable to minimize losses due to the increase in the number of nonlinear loads (deformed power). Currently, there is rapid development in new adaptive, non-adaptive, and especially hybrid methods of digital signal processing. Nowadays, modern methods of digital signal processing maintain a key role in research and industrial applications. Many of the best practices that have been used to control shunt active power in industrial practice for decades are now being surpassed in favor of new progressive approaches. This systematic research review classifies the importance of using advanced signal processing methods in the field of shunt active power filter control methods and summarizes the extant harmonic extraction methods, from the conventional approach to new progressive methods using genetic algorithms, artificial intelligence, and machine learning. Synchronization techniques are described and compared as well.

Shunt active power filtering with reference current generation based on dual second order generalized integrator and LMS algorithm

For reducing the carbon emissions from utility sector, it is important to improve the efficiency of network and electrical loads. Current harmonics are responsible for the degradation of the system as well as load efficiency. The propagation of current harmonics into the grid can be prevented with shunt active power filters (SAPFs). Reference current generation (RCG) is critical for SAPF operation. This paper presents the control of SAPF with RCG based on least mean square (LMS) and dual second order generalized integrator (SOGI). The two SOGIs separately process grid voltage and load current to determine the respective fundamental in-phase component (FPC) and fundamental quadrature component (FQC). FPC and FQC of grid voltage are used to determine the phase angle of fundamental grid voltage. With LMS algorithm the distorted current can be decomposed into fundamental active (FA), fundamental reactive (FR) and harmonic components. However, the dynamic response of LMS based estimation is poor when the same learning rate is used for all components. FQC of load current, estimated with SOGI, can be processed by LMS algorithm to separate FA and FR components. RCG can be implemented with the computed phase angle and FA component. In LMS algorithm, as only two components are to be separated, two different learning rates can be easily specified. This results in faster dynamic response for LMS algorithm and has consequent positive impact on RCG and SAPF operation. Also, the computational complexity is considerably reduced. The performance of SAPF with the proposed extraction algorithm is analyzed for different operating conditions and comparative analysis is carried out.

Design of Multi-Objective-Based Artificial Intelligence Controller for Wind/Battery-Connected Shunt Active Power Filter

Nowadays, the integration of renewable energy sources such as solar, wind, etc. into the grid is recommended to reduce losses and meet demands. The application of power electronics devices (PED) to control non-linear, unbalanced loads leads to power quality (PQ) issues. This work presents a hybrid controller for the self-tuning filter (STF)-based Shunt active power filter (SHAPF), integrated with a wind power generation system (WPGS) and a battery storage system (BS). The SHAPF comprises a three-phase voltage source inverter, coupled via a DC-Link. The proposed neuro-fuzzy inference hybrid controller (NFIHC) utilizes both the properties of Fuzzy Logic (FL) and artificial neural network (ANN) controllers and maintains constant DC-Link voltage. The phase synchronization was generated by a self-tuning filter (STF) for the effective working of SHAPF during unbalanced and distorted supply voltages. In addition, STF also does the work of low-pass filters (LPFs) and HPFs (high-pass filters) for splitting the Fundamental component (FC) and Harmonic component (HC) of the current. The control of SHAPF works on d-q theory with the advantage of eliminating low-pass filters (LPFs) and phase-locked loop (PLL). The prime objective of the projected work is to regulate the DC-Link voltage during wind uncertainties and load variations, and minimize the total harmonic distortion (THD) in the current waveforms, thereby improving the power factor (PF).Test studies with various combinations of balanced/unbalanced loads, wind velocity variations, and supply voltage were used to evaluate the suggested method’s superior performance. In addition, the comparative analysis was carried out with those of the existing controllers such as conventional proportional-integral (PI), ANN, and FL.

Performance improvement of shunt active power filter based on indirect control with a new robust phase-locked loop

Introduction. Since the development of the first active power filter (APF) in 1976, many efforts have been focused on improving the performances of the APF control as the number of different nonlinear loads has continued to increase. These nonlinear loads have led to the generation of different types of current harmonics, which requires more advanced controls, including robustness, to get an admissible total harmonic distortion (THD) in the power system. Purpose. The purpose of this paper is to develop a robust phase-locked loop (PLL) based on particle swarm optimization-reference signal tracking (PSO-RST) controller for a three phase three wires shunt active power filter control. Methodology. A robust PLL based on PSO-RST controller insert into the indirect d-q control of a shunt active power filter was developed. Results. Simulation results performed under the MATLAB/SimPowerSystem environment show a higher filtering quality and a better robustness compared to the classical d-q controls. Originality. Conventional PLLs have difficulty determining the phase angle of the utility voltage sources when grid voltage is distorted. If this phase angle is incorrectly determined, this leads to a malfunction of the complete control of the active power filters. This implies a bad compensation of the current harmonics generated by the nonlinear loads. To solve this problem we propose a robust and simple PLL based on PSO-RST controller to eliminate the influence of the voltage harmonics. Practical value. The proposed solution can be used to improve the functioning of the shunt active power filter and to reduce the amount of memory implementation.

Power Quality Enhancement Using Particle Swarm Optimization Based Shunt Active Power Filter

The shunt active power filter is one compelling arrangement is utilized for reducing the source current harmonics distortion in nonlinear load distribution system. The synchronous reference frame control algorithm utilized to creating current controlled reference signals. The acquired reference control signals are compared with hysteresis controller for better switching of shunt active power filters. Generally SRF with PI controlled shunt active power filter are used to compensation of harmonic. But, they won't give better results to bigger variety loads. In these papers a particle swarm optimization (PSO) system is proposed for better tuning of PI values of SRF with PSO-PI controlled shunt active power filter. The simulation results without and with conventional PI and furthermore with PSO-PI is analyzed for nonlinear load distribution system.

Advanced Control of Single-Phase Shunt Active Power Filter Based on Flying Capacitor Multicell Converter

Shunt Active power filters (SAPFs) are a prevalent device for improving power quality (PQ) in power systems by reducing harmonics caused by nonlinear loads. This paper developed a viable approach for improving power quality by utilizing a very promising power conversion device, namely the flying capacitor multicell inverter (FCMI). Advanced control of single-phase four-level FCMI topology operating as SAPF based on a two-loop structure is proposed. In the inner loop, the backstepping controller is adopted to compensate for the harmonic and reactive currents absorbed by the nonlinear load as well as to regulate the flying capacitors (FCs) voltages. Furthermore, since the regulation of the DC bus voltage is an important process in the control of SAPF, an adaptive neuro-fuzzy inference system (ANFIS) is proposed as an appropriate control technique to regulate the DC voltage to its optimal value in the outer loop. Lastly, the simulation results proved the effectiveness of the proposed controller in terms of tracking, regulation, and robustness.

Analysis of Levenberg Marquardt - ANN based reference current generation for control of shunt active power filter

Shunt active power filter (SAPF) is an inevitable solution that needs to be installed by industrial consumers to prevent the power quality issues due to the non-sinusoidal currents drawn by non-linear loads. SAPF provides harmonic current compensation and reactive power management to eliminate the current related power quality issues. Various reference current generation schemes such as d-q theory, instantaneous reactive power theory, discrete Fourier transform, PI controller, fuzzy logic etc. are reported. Artificial neural network (ANN) is an emerging concept in SAPF for reference current generation. In this paper, detailed analysis of Levenberg Marquardt–feedforward ANN based reference current generation scheme for the control of SAPF is presented. This paper mainly focuses on successful implementation of Levenberg Marquardt algorithm for training the feedforward ANN network for reference current generation with different non linear and unbalanced load condition. Performance analysis of Leven Marquardt – ANN based reference current generation for the control of SAPF under different operating condition is carried out in MATLAB/SIMULINK platform.

Takagi‐Sugeno exact model and linear matrix inequalities for an active power filter control

In order to take advantage of the capabilities of a shunt active power filter (SAPF), the design of an adequate control scheme must be developed; generally, the SAPF control scheme corresponds to a cascade control composed of an inner loop and an outer loop. This article approaches the design of an inner loop control based on linear matrix inequalities (LMIs) for a SAPF with LCL coupling filter. The control design begins with the system rewriting in exact Takagi-Sugeno (TS) models, in the sequel, through the use of a quadratic energy function, and considering the closed-loop system, the Lyapunov direct method to establish LMI conditions is used. This proposal of inner loop control is called TSLMI, and in conjunction with a PI control, a PI-TSLMI cascade control scheme is configured. The SAPF objectives are the reduction of the total harmonic distortion (THD) in the mains current, the power factor (PF) correction, and facing load changes. The results show a correct performance of the proposed PI-TSLMI for both simulation and experimental tests.

A New Optimal Current Controller for a Three-Phase Shunt Active Power Filter Based on Karush–Kuhn–Tucker Conditions

This paper presents an algorithm for finding the optimal control for a current controller that operates as a part of a control system of a shunt active power filter. The algorithm is based upon the Karush–Kuhn–Tucker conditions for finding an optimal value where control signal is limited and constraints create a cube. The explicit solution of the Karush–Kuhn–Tucker problem is presented and simplified calculations are given to lower calculation complexity. The presented Karush–Kuhn–Tucker algorithm is compared with a classical PI controller. It is given the algorithm for finding the optimal parameters of the PI controller and the behavior of the PI controller is compared with the presented algorithm. Attention has been paid to the saturation of controllers in commutation states of load currents, which has a negative impact on the final performance of the controllers and the controlled shunt active power filter. The paper also presents the software and hardware platforms applied to run the presented algorithms in real-time. For both controllers, the shunt active power filter response is shown using real experimental results. The results of the experiments prove better behavior regarding the presented algorithm, especially in the case of commutative load currents, where the output signals from other controllers become saturated.

Enhanced Exponential Reaching Law-Based Sliding Mode Control of ShAPF in an EDS

In this paper a three phase Shunt Active Power Filter (ShAPF) is proposed to address the current related issues in a three phase Electrical Distribution System (EDS). A sliding mode controller (SMC) and an Enhanced Exponential Reaching Law based SMC (EERL-SMC) is proposed for a ShAPF to compensate the load current. The controller’s performance is tested by injecting the current harmonics into the system. A non-linear load along with different loads on the distribution side is connected in parallel in a distribution network at Point of common coupling (PCC). Modelling of the system is done using state space analysis. Stability of the system is analyzed using the state feedback approach. The reference source currents are generated using instantaneous PQ theory. For variations in the load, the THD in the source current is realized. It is found that EERL-SMC is more effective for a ShAPF in reducing the high frequency oscillations and settling time for convergence. The source voltage and current waveforms are observed to be sinusoidal in nature. Both the controllers are effective in reducing the THD levels in the source current as per the IEEE standards. A comparison between the controllers is presented in terms of settling time, THD in source current. PSCAD v4.6 is used for simulation works.