Active Power Filter Control Research Articles

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.

Three-phase four-wire shunt hybrid active power filter model with model predictive control in imbalance distribution networks

<span lang="EN-US">This paper presents a harmonic reduction and load imbalance model in a three-phase four-wire distribution network. This model uses a hybrid active power filter, a passive inductor and capacitor filter, and an active power filter in the form of a three-phase, four-leg connected grid inverter. The switching of the voltage source converter on this filter uses finite control set model predictive control (FCS-MPC). Control of this hybrid active power filter uses model predictive control (MPC) with a cost function, comparing the reference current and prediction current with mathematical modelling of the circuit. The reference current is taken from the load current by extracting dq, and the predicted current is obtained from the iteration of the voltage source converter (VSC) switching pattern. Each combination is compared with the reference current in the cost function to get the smallest error used as a power switching signal. Modelling was validated by using MATLAB Simulink. The simulation results prove a decrease in harmonics at a balanced load from 22.16% to 4.2% and at an unbalanced load, reducing the average harmonics to 4.74%. The simulation also decreases the load current imbalance in the distribution network. Reducing the current in the neutral wire from 62.01%-0.42% and 11.29-0.3 A.</span>

A Grid-Connected Solar PV/Wind Turbine Based Hybrid Energy System Using ANFIS Controller for Hybrid Series Active Power Filter to Improve the Power Quality

The current needs of more nonlinear loads and the frequent usage of single-phase loads in three-phase system drastically create power quality issues in the grid-connected system. As a consequence, it creates an undesirable power quality issue (PQI) in the form of a change in the nature of voltage and current magnitude and waveforms in the power system. The voltage-related PQI leads to a huge disturbance in the system when compared with the current-related PQI. The hybrid series active power filter provides grids with the required voltage in series and suppresses the voltage-related harmonics caused by grid-connected nonlinear loads. The present work deals with an adaptive neurofuzzy inference system controller for the generation of a reference voltage signal that uses a reduced active filter rating. The simulation study was done in the MATLAB 2020b/Simulink environment and the experimental effectiveness of the proposed ANFIS controller was compared with that of a conventional controller. In the grid-connected system, this system prevents voltage quality problems such as voltage sag, flickering, voltage swell, neutral currents, and reactive power. The renewable energy sources interfaced into the DC-link minimize short and long voltage challenges so that they improve the overall performance of the system. In accordance with IEEE standard 519-1992, a prototype model was proved to demonstrate that the power delivery system works effectively under different conditions and reduces the total harmonic distortion by approximately 30%, which is less than the 5% acceptable limit.

An improved robust model predictive and repetitive combined control for three-phase four-leg active power filters with fixed switching frequency

An improved robust model predictive control (MPC) method for a three-phase four-leg active power filter (APF) is proposed in this paper. First, the decoupling model in abc coordinates of the four-leg APF is derived, and then an optimal control law is also deduced based on the calculation of the partial derivation of the cost function, which is composed of the current tracking error and control quantity with a weighted coefficient. In addition, repetitive control (RC) is introduced to eliminate the prediction error inherent in the model. Finally, the influence of control parameters on the stability of the system is analyzed by the Jury stability criterion, the performance of the proposed method has also been investigated with the perturbations of the filter inductor parameters, and strong robustness, fixed switching frequency and rapid dynamic response of the whole system can be obtained. Simulation and experimental results show the effectiveness and feasibility of the proposed method.

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.

Implementation of modified switching table for direct power control of shunt active power filter

ABSTRACT The direct power control (DPC) technique has been proposed as an alternative method to sophisticated current control techniques in order to synthesise the instantaneous active and reactive powers fed by the inverter into the grid. The method selects the voltage vector of the inverter based on the quantised values of the instantaneous active and reactive power errors and thereby controls the power exchange between inverter and the Point of Common Coupling (PCC) directly. The method has better dynamic performance, an inherent decoupling of active and reactive powers and robustness against parameter variations. However, the application of DPC to shunt active power filter (SAPF) requires high sampling frequency in the digital controller and at the same time suffers from the issue of the large variation in the switching frequency. This work proposes implementation of a modified switching table of DPC using multisector Discrete Space Vector Modulation(DSVM) concept for the SAPF to alleviate the problem of high sampling frequency requirement and variation in switching frequency and reduce burden on the controller. The performance of the method is evaluated in MATLAB Simulink® environment, verified with 2 kVA laboratory prototype under various load conditions and compared with constant switching frequency-predictive deadbeat DPC method.

Hybrid Active Power Filter for Power Quality Improvement

A Deadbeat current controller for an LC-coupling hybrid active power filter is proposed, which can track with the reference compensation current with low steady- state error and fast dynamic response. Moreover, it can lead Hybrid Active power Filter to be operating at a fixed switching frequency with low output current ripples, thus reducing the size of the filtering circuit. The stability issue and parameter design of the proposed deadbeat current controller are analyzed and discussed. Finally, the compensating performance of the deadbeat current controller for the Hybrid Active Power Filter (LC-HAPF) is verified by simulation compared with the conventional hysteresis bandwidth modulation control, the proportional-integral (PI) control, and the proportional multi-resonant control for the LC-HAPF, which shows its effectiveness and superior compensating performances.

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.

A Frequency Adaptive Repetitive Control for Active Power Filter With 380V/75A SiC-Inverter

Active power filters (APFs) with repetitive control (RC) could compensate for the harmonics. However, there are some problems in IGBT-380V-APFs with RC, such as the adaptability of grid frequency varying because of the noninteger value of RC parameters. SiC- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s that could reach high switching frequency provide a new way to increase the compensation accuracy and the frequency adaptability for 380V/APFs. In this article, a novel frequency adaptive fast repetitive control (FAFRC) for APF with SiC- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> inverter to achieve optimal performance in variable frequency girds through changing RC order <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> was proposed. Taking the advantage of the high switching and sampling frequency of SiC-APF, the control method proposed could compensate for the harmonics more accurately with an integer RC order <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> . The control method with 50 kHz switching and the sampling frequency is described, designed, and verified experimentally in a two-level 380V/75A APF prototype made up of SiC- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s, which volume is 37L that 66% of IGBT-APFs. The results obtained that 380V/75A-SiC-APFs with the control method proposed have a high compensation accuracy (THD<5%) with the grid frequency variations.

Neural network–based adaptive fractional-order terminal sliding mode control

This paper proposes an adaptive fractional-order (FO) terminal sliding mode control (TSMC) scheme to the robust current control of active power filter (APF) using a recurrent meta-cognitive fuzzy neural network (RMCFNN). An FO TSMC is developed by considering that the parametric perturbations and the external disturbances of APF are bounded. Compared with conventional TSMC approach, the proposed scheme, with an FO sliding surface, can obtain enhanced finite-time high-precision tracking performance due to another degree of freedom. Then, a novel observer-based FO TSMC is derived to achieve an absorbing model-free feature arising from RMCFNN. To improve the capabilities in managing the uncertainties, the specific online updating schemes for the structure and parameters of RMCFNN are designed. Meanwhile, closed-loop stability and finite-time convergence characteristic can be achieved using Lyapunov theory. Finally, simulation and experimental results indicate that the proposed observer-based FO TSMC can be easily implemented by microcontroller and has superior control performance compared with other existing schemes.

A novel optimizing PI control of shunt active power filter for power quality enhancement

In this paper, shunt active power filter (SAPF) is designed to address the problem of current harmonics in the source current arising from a nonlinear load and improve the quality of electric power. That will be by compensating reactive power and harmonic currents. The PI controller responsible for DC-link energy storage tuning was developed using the Lévy flight distribution algorithm (LFA). It is a novel, previously unused optimization approach to suggest relative gain Kp and integration gain Ki gain values for the PI controller. This approach aims to get the best dynamic performance of SAPF, speed up the convergence rate, get the fastest best stability and bypass constant voltage advancement for DC-link. The model was tested and implemented in MATLAB simulation software. The result of total harmonic distortion THD showed the efficiency of this method compared with the results of traditional PI. The design of the model in the current reference frame was based on instantaneous reactive power (pq) theory.

Precise model of LC active power filter and feedback linearization control

The problems of regulating power quality are more prevalent. In general, Active power filter(APF) is one of the best solution. But the influence of load impedance and grid impedance were widely ignored by a great number of papers, supposed the load voltage is constant and modeling in APF singly, which can’t describe the system accurately. Firstly,there are build an accurate model, including LC APF, load and grid impedance. Secondly, applying feedback linearization and proportional resonant differentiation (FL-PRD) control in inner current loop. Then analyze the influence of load and grid impedance. Once more,checked the accuracy of builded accurate model by Simulink and experiment. Eventually, compare mentioned algorithm in the paper with classical proportional resonant (PR) controller. The results show that it is rather important to set up an accurate model and the proposed algorithm gets a perfect capacity.

Nonlinear Observation and Control of Series Active Power Filters in the Presence of Voltage Sags

This study addresses the problem of controlling series active power filters for voltage sag compensation. Indeed, we can control this kind of filter to generate a voltage series that compensates the grid voltage sag in order to protect the sensitive loads against this perturbation. This study is aimed at seeking a control strategy that meets the main control objective, which is the compensation of grid voltage sags and this by considering the following technical constraints: (i) the nonlinearity of the system dynamics, (ii) the high dimension of the system model, and (iii) the inaccessibility of some system variables to measurements. To meet the main control objective, we propose a nonlinear controller that is designed based on the system nonlinear model, using the backstepping technique. This controller involves a nonlinear regulator and a grid observer. The former copes with the compensation issue. The observer provides online the grid voltage estimations. In addition to a theoretical analysis of the control system, the performances of the proposed controller are evaluated by simulation using MATLAB/Simulink.

A novel strategy for high performance fault tolerant control of shunt active power filter

A novel strategy for high performance fault tolerant control of shunt active power filter

A direct current control strategy based on vector resonance controller for shunt active power filter

From the perspective of complex vector, this paper derives the mathematical model of the three-phase three-wire shunt active power filter (SAPF) current control object, and based on it, derives the corresponding vector resonance control expression form coordinate transformation, and the steady-state accuracy, anti-interference ability, and stability of the system are analyzed. The deduction demonstrates the equivalence of the traditional detection load harmonic current control and the direct grid current control in this paper, and the consistency of the current regulator. Then, a direct vector resonance control structure of grid current based on the dq coordinate without detecting harmonic currents is designed, and the digital realization of the vector resonance controller, the adaptive ability to frequency, and the phase lag at the high-order control frequency are designed. And finally experimental verification under different working conditions is presented, the experimental results prove the practicability and effectiveness of the direct current control strategy based on the vector resonance controller proposed in this paper.

MPC with Space Vector Phase-Shift PWM (SV-PSPWM) Technique with Harmonic Mitigation Strategy for Shunt Active Power Filters Based on H-Bridge Multilevel Converter

This article presents a model predictive current control of a shunt active power filter based on 7-level cascaded H-bridge converters. By using the spacial vector modulation approach into the model predictive control, a considerable reduction of the computational burden is achieved and makes possible the real-time implementation in a custom experimental setup. Then, the current harmonics on the grid side, caused by non-linear loads connected to the point of common coupling, are compensated. The experimental results confirmed the feasibility and efficacy of the proposed controller.

Nonlinear control of active power filter connected to photovoltaic system

The paper presents a nonlinear control of shunt active power filter operating in presence of nonlinear loads. The said filter is connected to PV system in order to deliver the active power to load. The main control objectives are: (i) compensation of harmonic currents and the reactive power caused by the nonlinear load; (ii) regulation the DC bus voltage of inverter. The control problem is dealt with a nonlinear controller that is developed by using the Lyapunov technique to cope with the harmonic’s issue. The outer-loop regulates the DC bus voltage of the static converter. The controller performances are validated by simulation in MATLAB\\Simulink.

Cascaded controller for single-phase shunt active power filter and STATCOM

Cascaded controller for single-phase shunt active power filter and STATCOM

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.