Three-phase Shunt Active Power Filter Research Articles

Advanced control of double stage grid-tied three phase photovoltaic systems with shunt active power filter

This paper explores the challenges associated with the control of a two-stage three-phase electrical grid connected to a photovoltaic (PV) system. The objectives encompass: i) maximizing the available PV power, ii) controlling the DC-link voltage to a predetermined setpoint, and iii) considering that power quality has become an important measure in a distribution electrical network where different loads are connected, the third objective will mainly focus on ensuring power factor correction (PFC). To achieve these objectives, two loops of nonlinear controller are developed. In the outer loop, the duty cycle of a boost converter is controlled using a hybrid technique of backstepping technique and the perturb & observe (P&O) algorithm. In addition, the inner loop employs a hybrid automaton approach to tackle the challenges of a three-phase shunt active power filter (SAPF). The results have been verified through numerical simulation using MATLAB/Simulink power systems environment.

Frequency-adaptive odd-harmonic repetitive control scheme for three-phase shunt active power filters

Repetitive control (RC), which can track the periodic input or suppress the periodic disturbance with a zero steady-state error, is a promising control strategy for shunt active power filters (SAPF). However, the conventional RC (CRC) scheme will suffer a severe performance degradation caused by the grid frequency variations. In this article, a frequency-adaptive odd-harmonic repetitive control scheme with a single and fixed sampling rate is proposed for SAPF to deal with grid frequency variations and provide fast transient response for RC system. The frequency-adaptability of proposed repetitive control scheme can be implemented by updating the coefficients of the approximate expression for the delay unit in repetitive controller. The FIR filter based on Lagrange linear interpolation is used to transform the multirate repetitive control system into single-rate repetitive control system to address the problems caused by the multirate repetitive control system. Moreover, a fractional-order linear compensator with a simple structure is designed to compensate the magnitude and phase of the system accurately. Compared with other classical repetitive control strategies, the proposed repetitive control scheme can provide a better adaptation to the steady-state deviation and dynamic variation of grid frequency and ensure the control performance of SAPF system. Simulation and experimental results verify the effectiveness of the proposed control scheme.

Fault-tolerant shunt active power filter with synchronous reference frame control and self-tuning filter

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.

Comparative analysis of control techniques using a PV-based SAPF integrated grid system to enhance power quality

The deterioration of power quality due to the increased adoption of Power Electronic Switching Devices is a major concern for electrical engineers. In addition to industrial loads, household loads cause numerous disturbances on the utility side, such as sags, ripples, flickers, and harmonics. It is possible to create power quality problems in a system or to have them arise due to a faulty consumer. This paper implements a renewable energy system with a Shunt Active Power Filter (SAPF) that injects PV energy into a power grid in the presence of nonlinear loads and under various load conditions to maintain power quality and improve power grid capacity. The Perturb and Observe (P&O) algorithm adjusts boost converter duty cycles to track the Maximum Power Point (MPP). The boost converter output is connected to the grid via a SAPF. The effectiveness of SAPF in reducing total harmonic distortion has been investigated using various reference current generation strategies of control methods and improved maximum power factor. The voltage source inverter switches are controlled through hysteresis current control. Moreover, this paper explains how to regulate the dc link capacitor of a three-phase SAPF with PI, fuzzy, and Adaptive Fuzzy Neuro Inference System (ANFIS) controllers to enhance power quality and compensate for reactive power and harmonic current caused by nonlinear loads. This system is developed under balanced and unbalanced nonlinear loads in MATLAB-Simulink. Furthermore, SRF-based reference current generation techniques with ANFIS controller to achieve better performance tested for control performance in proto-type hardware model to validate the proposed performance of this system.

Power Quality Improvement using a New DPC Switching Table for a Three-Phase SAPF

This research focuses on the analysis and design of robust direct power control (DPC) for a shunt active power filter (SAPF). The study proposes a novel switching table design based on an analysis of the impact of inverter switching vectors on the derivatives of instantaneous reactive and active powers. The goal is to reduce the number of commutations by eliminating null vectors while maintaining the desired DC-bus voltage using a PI regulator-based anti windup technique. Additionally, a robust PLL structure-based band pass multivariate filter (BPMVF) is utilized to enhance the network voltage. The research demonstrates the effectiveness of the suggested power control through extensive simulation results, showing high performance in both transient and steady-state conditions. The proposed approach offers the advantages of sinusoidal network current, and unitary power factor, and eliminates the need for current regulators and coordinate transformations or PWM generators. Further research directions could explore the practical implementation and real-world performance of this technique in power systems.

Neural network controller for five phases shunt active power filter applied for five phase embarked electrical network

This paper discusses neural network ANN controller applied for five phase shunt active power filter. Three-phase shunt active power filters are widely studied, however in this paper we investigate to extend their application to five phase embarked electrical network. Two-level five phase inverter is used as a shunt active power filter to reduce harmonics and compensate reactive power injected by a five-phase diode rectifier. An artificial neural network controller has been used to regulate the DC side of the inverter, thereby contributing to the calculation of the reference harmonic currents on the one side and controlling the injected harmonic currents on the other. Self-tuning filter (STF) is used to calculate the reference current. By using STF allow to extract the voltage and current fundamental components in the α-β-axis directly without the use of a phase-locked loop (PLL). Simulation results shows that the ANN controller presents appreciable performances in references tracking and the proposed five-phase shunt active power filter provides a sinusoidal supply current in phase with the line voltage with low harmonic distortion.

FPGA-Based Hardware in the Loop of Optimized Synergetic Controller for Active Power Filter

This paper presents a discrete-time synergetic controller (DTSC) enhanced with ant colony optimization (ACO) technique for a shunt active power filter (SAPF). The developed controller is designed under MATLAB/Simulink environment; then, field-programmable gate array (FPGA) in the loop (FIL) technique is used to implement the DTSC model. The proposed DTSC parameters are optimally tuned according to ACO methodology. The DTSC-ACO should enhance power quality and eliminate grid current harmonics using an indirect current-controlled three-phase SAPF. Note that, the designed FPGA controller integrates the items needed to drive the SAPF. This digital implementation satisfies the hardware and recommended performance. In fact, it reduces significant resources and execution time. The experimental validation is carried out on Virtex-6 ML605 FPGA Xilinx Evaluation Kit using VIVADO processing. A total harmonic distortion (THD = 2.72%) is obtained for the grid current. Thus, the results obtained confirm proper operation of the developed approach. In addition, the proposed DTSC shows good dynamic performance during load step change and output voltage variation.

Advanced Control Algorithm for Three-Phase Shunt Active Power Filter Using Sliding DFT

This paper describes n digital control algorithm for a three-phase shunt active power filter (APF) using switching–sliding discrete Fourier transform (SSDFT). Traditionally, APF control algorithms use first harmonic detector circuits, which can be implemented using the SDFT algorithm. The classical SDFT algorithm is characterized by long-term stability issues, resulting from numerical errors. Many complex modifications to improve the stability of the SDFT algorithm have been proposed in the scientific literature. This article proposes a solution to the SDFT stability problem using the basic structure of the algorithm. The authors propose the use of the switching SDFT algorithm, where two original SDFT algorithms are implemented in parallel. Both algorithms are turned on alternately after a set period of time and reset to zero in order to reset numerical errors causing their unstable operation. Compared to the classical three-phase SDFT algorithm, the three-phase SSDFT requires only about 25% more arithmetic operations. The proposed approach has been validated using experimental tests and dramatically reduces the numerical errors. The control algorithm has been implemented using the TMS320F28379D microcontroller. The sampling method using only the internal A/D converter of a microcontroller is also presented. The article includes the experimental test results of the complete APF.

АНАЛІЗ СТІЙКОСТІ СИСТЕМИ СТАБІЛІЗАЦІЇ НАПРУГИ НА НАКОПИЧУВАЛЬНОМУ КОНДЕНСАТОРІ ТРИФАЗНОГО ПАРАЛЕЛЬНОГО АКТИВНОГО ФІЛЬТРА

The object of the study is a three-phase shunt active power filter, which consists of a two-level voltage inverter, a capacitive storage device and a damping RL-link. Decomposition of the object of study according to the rate of motion of a dynamic system makes it possible to divide this system into two subsystems, interconnected by control. The influence of the dynamic characteristics of the low-pass filter, which acts as a subsystem of communication between the voltage stabilization circuit on the capacitor of the three-phase shunt active power filter and the circuits of compensating current, on the stability of the system is considered. The formation of the compensation current is carried out by forcing the introduction of sliding modes of the first order. The mathematical model of the voltage stabilization subsystem on the capacitor using the vector of the equivalent control under the assumption of the existence of a sliding mode in the formation of the compensation current was built. The analysis of the stability of the voltage stabilization system using a low-pass filter of the second order on the first approximation was performed. To do this, the characteristic equation of a closed system for which an interval characteristic polynomial was constructed, the Kharitonov theorem, and the Rauss-Hurwitz method for a family of these polynomials was used. To confirm the theoretical assumptions, a simulation model was built and the results of digital modeling were analyzed. References 9, figure 1.

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.

Performance Analysis of Three-Phase Shunt Active Power Filter for Harmonic Mitigation

Aims: To carried out performance analysis of a shunt active power filter (SAPF) for harmonics mitigation.
 Study Design: Experimental design through simulation studies using P-Q Theory and proportional integral controller.
 Place and Duration of Study: Department of Physics, Nasarawa State University Keffi, main campus, Nigeria, between October 2020 and September 2021.
 Methodology: Primary and secondary data were obtained using AVO Digital Multimeter and manufacturers’ datasheets from Schneider electric website to capture required system parameters, SAPF was designed using a Voltage Source Inverter model to represent the Three-Phase source, and P-Q Theory with PI Control was used for reference current extraction. The SAPF was modeled, designed and simulated using MATLAB-Simulink and analyzed under different nonlinear load conditions and harmonic spectrum to achieve low Total Harmonic Distortion (THD).
 Results: The THD in the unbalanced system voltages before the application of SAPF was found to be 12.6%, 11.4% and 11.2%, while after the application of SAPF was 2.2%, 2.5% and 2.5% for phase voltages a, b and c respectively. The grid currents indicated THD of 27.2%, 30.9% and 31% before application of SAPF and 2.2%, 2.2% and 2.1% after application.
 Conclusion: The use of non-linear loads; has adverse effects on the quality of electric power as well as phase voltage and frequency waveforms. The use of SAPF is of vital importance in improving electric power quality for reliable power supply and quality service delivery.

Is It Correct that the Higher Detection Accuracy of Single-Phase Shunt APF Harmonic Current Detection, the More Effective the Detection?

Is it correct that the higher the detection accuracy of a single-phase shunt active power filter (SPSAPF) harmonic current detection (HCD) is, the more effective the HCD is? To answer the question, an interesting view correction for evaluating an SPSAPF HCD is proposed in this paper. The main points of the proposed view correction are as follows: The answer to the question is Yes when the load current changes periodically but No when the load current changes non-periodically. The proposed view correction also applies to a three-phase shunt active power filter; thus, it has general applicability. Its existence and feasibility are confirmed by experimental results.

A high gain observer design for the three-phase shunt active power filter interfacing a photovoltaic source

In this article, a nonlinear observer is designed for a system consisting of a PVS photovoltaic source associated with a shunt active power filter (SAPF) and connected to a three-phase electrical network. In addition to improving the quality of energy in the distribution network (unity power factor), the use of SAPF also allows the injection of photovoltaic energy into the network. Since the system model is nonlinear and some variables are unknown (inaccessible to measurement), a high-gain observer is constructed. The advantage of this solution lies in the estimation of the unmeasured state variables (variables of the photovoltaic source). It is shown using theoretical analysis, under certain conditions of persistent excitation, that all estimation errors disappear exponentially. The effectiveness of the solution is verified by numerical simulation under Matlab/Simulink.

Flatness-SVPWM Control for Three-Phase Shunt Active Power Filter Based on Five-Level NPC Inverter

The increasing use in the industry of nonlinear loads based on power electronic elements has introduced serious perturbation problems in the electric power distribution grids. These nonlinear loads generate non-sinusoidal currents to the mains which degrade the system's performance. Active power filters have been developed over the years to solve these problems and improve power quality. This study focuses on the use of a shunt active power filter to compensate nonlinear load's current harmonics and reactive power. To this end, a regulator based on the flatness control technique combined with an SVPWM strategy for a three-phase shunt active power filter based on a five-level neutral-point-clamped (NPC) inverter is used. The control objectives of this work are twofold: i. compensating the current harmonics and the reactive power produced by the nonlinear loads, and ii. regulating the inverter's DC capacitor voltage. To achieve these objectives, two cascaded loops are designed; an inner loop for the reactive and harmonic currents compensation based on a flatness controller and an outer loop for the DC voltage regulation based on a PI regulator. The simulation results are developed under MATLAB/Simulink environment to prove the satisfactory performance of the proposed controlled system.

Comparative Analysis of Two Methods of Calculating the Prescribed Current in a Shunt Active Filtering System

- In this paper, the performance of a three-phase shunt active power filter (APF) using the instantaneous power theory (p-q theory) has been compared with that corresponding to the use of the synchronous reference frame (SRF) based method. It is clear that, under balanced and sinusoidal voltage conditions, these two methods gives similar results. The entire system has been modeled using MATLAB-SIMULINK software. The simulation results demonstrate the applicability of both methods for the APF control.

Lyapunov based harmonic compensation and charging with three phase shunt active power filter in electrical vehicle applications

With the increasing proliferation of high-tech loads and electrical vehicle (EV) charging stations, shunt active power filters (SAPFs) are contemplated to play a growingly substantial role in power distribution and delivery. In this regard, this paper proposes a Lyapunov based harmonic compensation and charging with the operation of three-phase SAPF as interface EV applications and the electric grid. The proposed control algorithm provides effective harmonics mitigation capability under various non-linear loads (NLLs) groups and grid disturbances. A noteworthy contribution of this paper is that a Lyapunov based proportional integral with anti-windup (PI with AW) control is proposed to regulate oscillations of the DC-link voltage without increasing DC-link capacitor size. The proposed control algorithm offers comprehensive solutions with several improvements, novelties and features as: (i) keeping the total harmonic distortion (THD) of source currents below recommended IEEE-519 limits, (ii) extraction of reference current and voltage signals based on Lyapunov estimator (LE) with effective and good harmonic rejection capability, (iii) achieving good dynamic performance with utilizing a Lyapunov based PI with AW control for the DC-link capacitor voltage and (iv) eliminating the necessity of any high-pass or low-pass filters with utilizing LE based orthogonal signal generation (OSG). Besides, comparative analyses with previous studies are handled to examine improvements provided by the proposed control algorithm. The feasibility and effectiveness of the proposed control algorithm are confirmed by PSCAD/EMTDC environment and DSP based PIL quasi-real time results.

Adaptive linear neuron control of three-phase shunt active power filter with anti-windup PI controller optimized by particle swarm optimization

In the present paper, particle swarm optimization technique (PSO) is used to tune anti-windup PI controller gains for DC bus voltage control of the shunt active power filter by offline simulation. The main advantage of the PSO tuning algorithm is to accurately estimate PI controller parameters and overcome the complexity of analytical calculation approaches as well as classical tuning methods. The sum of the total harmonic distortion of source currents and the DC bus's voltage error are used as a fitness function. The reference current is obtained using an artificial neural network named adaptive linear neuron (ADALINE). Three ADALINEs are trained online using the least mean square algorithm (LMS). The proposed system is designed by MATLAB/Simulink and validated experimentally through the dSPACE DS1104 platform. The analysis is done for various conditions, and the obtained results demonstrate the effectiveness of the controller in terms of performance, efficiency, and power quality enhancement.

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.

Vector Strategy of Formation of the Compensating Current of Shunt Active Filter In Sliding Mode

A space-vector strategy for controlling of a three-phase shunt active power filter (SAPF), which is connected to a utility grid in which there is a nonlinear load, is proposed. The filter consists of a semiconductor voltage inverter with fully controlled switches, a capacitive storage and a single-link output RL filter. The DC voltage of the storage capacitor is stabilized by a second-order sliding mode, which is based on the implementation of a finite double-twisting algorithm. To form the compensation current, an indirect control strategy and a space-vector algorithm for tracking the instantaneous value of the current of the "parallelogram" type are used. Space-vector method avoids ambiguity in the choice of vectors of the output voltage of the inverter under the solution of the problem of current tracking. The proposed algorithm uses the methods of projective geometry to determine the relative position of the spatial vectors of voltages and currents of the power supply system, so it does not contain the difficult mathematical operations for calculating inverse trigonometric functions. The selection of the appropriate output voltage vector of the SAPF inverter on the location of the end of the current error vector relative to some switching lines is based. Switching lines from the projections of the two-dimensional sliding surface on the plane α-β are formed. These projections are subject to further linear transformation, the matrix of which is non-degenerate. Linear transformation of projections of these sliding surfaces includes sequential operations of rotation at a fixed angle, parallel movement and application of the rotation matrix. This rotation matrix has constant coefficients, which change abruply at some points in time. The classical method of equivalent control is applied. The transition from one group of coefficients to another occurs based on the spatial location of the equivalent control vector, the coordinates of which are calculated in real time. The choice of the rotation matrix provides unambiguous determination of the spatial position and the choice of the corresponding output voltage vector of the SAPF inverter. A simulation model of the power supply system with a two-dimensional sliding mode and taking into account the features that are inherent in the real-time sliding mode is built, and the simulation results are analyzed. The "switching freeze" method to eliminate chattering was used. The proposed strategy with the traditional three-channels hysteresis algorithm of the compensation current tracking according to the criteria of the number of switches is compared.

Self tunning filter for three levels four legs shunt active power filter with fuzzy logic controller

The low harmonic distortion and reduced switching losses are the advantages of using the multilevel inverter. For this purpose, the three-level inverter is used in this paper as a three-phase four-leg shunt active power filter (SAPF). The SAPF is used to eliminate the harmonic current to compensate the reactive power current, and to balance the load currents under an unbalanced non-linear load. A fuzzy logic controller and self-tuning filters (STF) are used to control the active power filter (APF) and generate the reference current. To demonstrate the validity of the proposed control strategy, we compared it with a conventional p − q theory, under distortion voltage conditions and unbalanced non-linear load. The Matlab-Simulink toolbox is used to implement the algorithm of Fuzzy logic control. The performance of the SAPF controller is found very effective and adequate as compared with the p − q theory.