Control Of Shunt Active Power Filter Research Articles

Adaptive notch filter solution under unbalanced and/or distorted point of common coupling voltage for three‐phase four‐wire shunt active power filter with sinusoidal utility current strategy

In this study, the three-phase four-wire shunt active power filter (ShAPF) dealing with non-ideal point of common coupling (PCC) voltages will be presented. The instantaneous power theory is applied to design the ShAPF controller which shows reliable performances. An adaptive notch filter (ANF) is proposed to process those unbalanced and/or distorted PCC voltage. The power balance among utility, load and ShAPF while applying ANF is clarified by an in-depth explanation. The simulation results prove that the ANF can successfully facilitate the ShAPF in terms of compensating unbalanced/distorted current of loads under a non-ideal PCC voltage circumstance.

Faults Diagnosis in Five-Level Three-Phase Shunt Active Power Filter

In this paper, characteristics of open transistor faults in cascaded H-bridge five-level three-phase PWM controlled shunt active power filter are determined. Phase currents can’t be trusted as fault indicator since their waveforms are slightly changed in the presence of open transistor fault. The proposed method uses H bridges output voltages to determine the faulty phase, the faulty bridge and more precisely, the open fault transistor.

AC Grid Connected DFIG-Based Wind Turbine with Shunt Active Power Filter Based on Nonlinear Predictive Control

The paper presents an AC grid connection for wind energy conversion system (WESC) based on the doubly-fed induction generator (DFIG). A direct voltage control (DVC) approach is designed for applying the DFIG system to obtain a sinusoidal waveforms of the stator voltage. In order to compensate the harmonic produced by the three-phase Diode Bridge supplied by a passive circuit (rd, Ld), a shunt active power filter (SAPF) is connected between DFIG and this nonlinear load at the point of common coupling (PCC). In this work we are all deeply concentrated on development of a new control strategy using nonlinear predictive control (NPC) for SAPF. The proposed control strategy consists of two blocks. The first one is the calculation unit of SAPF reference currents that allows us to identify the disturbance currents. The second one is the nonlinear predictive controller based on currents control loop that provides the switching function of the three half-bridges based on IGBT transistors. The presented work in this paper is validated via simulation under MATLAB/Simulink on a 1.5 MW DFIG-based wind turbine connected to an AC grid, taking into consideration the compensation for the disturbance currents. The results obtained in this work appear to be satisfactory and promising.

English

This paper presents the design of Shunt Active power filter and simplified control of hybrid system (wind -hydel) system connected to two back-to-back converters in which one is connected to hydel turbine and the other is connected to wind turbine system through squirrel cage induction generators (SCIG) feeding three phase loads in isolated locations. The main objective of this work is to provide a better control algorithm for the VSC and to achieve maximum power tracking (M.P.T) through rotor speed control of the wind turbine driven S.C.I.G under varying speeds at the machine side and to control the magnitude and frequency of the voltage at load side and to eliminate the ripple content in the wave forms and to create the system balanced. The system also ensures in sending the power generate by SCIGw is complete to the load through the load- side converter and remaining power be store into ESBS. And at the identical time if the required active power of the load is more than the total power generated by SCIGw and SCIGh. Then the deficit power is supplied by the ESBS. Simulation models of the proposed hybrid system with SAPF and the simulation results are obtained in MATLAB using Simulink and Sim Power System set toolboxes, with different load condition at different wind conditions Keywords-small-hydel, squirrel-cage induction generator (SCIG), MPT, Voltage Source Converter (VSC.), Shunt Active Power Filter (SAPF).

Adaptive nonlinear control of three-phase shunt active power filters with magnetic saturation

Abstract The problem of controlling three-phase shunt active power filters (SAPF) is addressed in presence of nonlinear loads. Previous works generally design control for SAPF based on standard models that assume the involved magnetic coil to be linear. In reality, the magnetic characteristics of these components are nonlinear (especially in the presence of large magnetic flux density in the ferromagnetic core). In this paper, a new oriented control model for SAPF-load system, taking into account for the nonlinearity of coil characteristics, is developed. The control objective is twofold: (i) compensating for the current harmonics and the reactive power absorbed by the nonlinear load; (ii) regulating the inverter DC capacitor voltage. To this end, based on the new model, a nonlinear controller is developed, using the backstepping technical design. It is therefore able to ensure good performances over a wide range of variation of the load current. Moreover, the controller is made adaptive for compensating the uncertainty on the switching loss power. The performances of the proposed adaptive controller are formally analyzed using tools from the Lyapunov stability and the averaging theory. The supremacy of the proposed controller with respect to standard control solutions is illustrated through simulation.

Hysteresis Control for Shunt Active Power Filter under Unbalanced Three-Phase Load Conditions

This paper focuses on a four-wire shunt active power filter (APF) control scheme proposed to improve the performance of the APF. This filter is used to compensate harmonic distortion in three-phase four-wire systems. Several harmonic suppression techniques have been widely proposed and applied to minimize harmonic effects. The proposed control scheme can compensate harmonics and reactive power of the nonlinear loads simultaneously. This approach is compared to the conventional shunt APF reference compensation strategy. The developed algorithm is validated by simulation tests using MATLAB Simulink. The obtained results have demonstrated the effectiveness of the proposed scheme and confirmed the theoretical developments for balanced and unbalanced nonlinear loads.

Fuzzy Logic Controlled Shunt Active Power Filter for Harmonic Compensation and Power Quality Improvement

In this paper, a shunt active power filter based on fuzzy logic controller is modeled, simulated, and tested. The fundament of Instantaneous Reactive Power Algorithm is used for extracting compensated reference harmonic current. A fuzzy logic controlled shunt Active Power Filter (SAPF) Using Hysteresis Band Current (HBC) is applied to regulate the DC capacitor voltage of (SAPF) in order to improve the active filter dynamic, to ensure sinusoidal source currents and to produce a high power quality. The main goal of the proposed active filtering system is to maintain the THD well within IEEE-519 on harmonics levels. Simulation results through MATLAB/Simulink are presented and interpreted. It is demonstrated that the fuzzy logic controller improves the performance of the active power filter. The implementation of a shunt active power filter has high performance characteristics by using dSPACE system.

Construction and Detection Algorithm of SAPF

Harmonics of power system seriously affected the quality of electric power. Shunt Active Power Filter (SAPF) [1] which overcomes the shortcomings of passive filter (PF) has become main technology to suppress harmonic. In this paper, structure, mathematic model, detection method and control of SAPF are mainly analyzed and reviewed. With development of key technology of APF, it will have a better application prospect.

Application of Artificial Neural Networks for Shunt Active Power Filter Control

Artificial neural network (ANN) is becoming an attractive estimation and regression technique in many control applications due to its parallel computing nature and high learning capability. There has been a lot of effort in employing the ANN in shunt active power filter (APF) control applications. Adaptive Linear Neuron (ADALINE) and feed-forward multilayer neural network (MNN) are the most commonly used ANN techniques to extract fundamental and/or harmonic components present in the nonlinear currents. This paper aims to provide an in-depth understanding on realizing ADALINE and feed-forward MNN-based control algorithms for shunt APF. A step-by-step procedure to implement these ANN-based techniques in MATLAB/Simulink environment is provided. Furthermore, a detailed analysis on the performance, limitation, and advantages of both methods is presented in the paper. The study is supported by conducting both simulation and experimental validations.

Two-phase Three-wire Shunt Active Power Filter Control by Using the Single-phase P-Q Theory

This paper presents a study of a shunt active power filter (APF) to be applied to two-phase three-wire electric networks. The application of this new APF is presented and possible topologies are discussed. The control algorithm of the APF is based on the single-phase p-q theory, which is briefly reviewed. Then, alternative–αβ transformations for voltages and currents are proposed to implement the single-phase p-q calculations. These adaptations are followed by the description of the proposed current reference calculation algorithm. Digital simulation and experimental results validate the effectiveness of the proposed shunt APF and control algorithm in compensating current harmonics, reactive power and imbalances of two-phase three-wire loads, even under distorted mains voltage condition.

Artificial-Neural-Network-Based Phase-Locking Scheme for Active Power Filters

This paper presents a phase-locking control scheme based on artificial neural networks (ANNs) for active power filters (APFs). The proposed phase locking is achieved by estimating the fundamental supply frequency and by generating a phase-locking signal. The nonlinear-least-squares-based approach is modified to estimate the supply frequency. To improve the accuracy of frequency estimation, when the supply voltage contains harmonics that are not known, a prefiltering stage is introduced. In shunt APF applications, not only the information of frequency is sufficient but also the phase information of the supply voltage is required to generate a unit template that is phase-locked to the supply voltage. Therefore, in this paper, an adaptive-linear-neuron-based scheme is proposed to extract the phase information of the supply voltage. The estimated system frequency and phase information are then utilized to generate a phase-locking signal that assures a perfect synchronization with the fundamental supply voltage. To demonstrate the effectiveness of the proposed approach, the synchronous reference frame ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$d{-}q$</tex></formula> theory) shunt APF control method with the proposed ANN-based phase-locking scheme is adopted. The performance of the proposed ANN-based approach is verified experimentally with different supply systems and load conditions.

Digital Control of Space Vector Pulse Width Modulation Based Shunt Active Filter

The wide spread use of power electronics equipments in modern electrical systems, has became a major concern due to the adverse effects of harmonics on all the sensitive equipments. This paper presents the implementation of shunt active power filter (SAPF) using source voltage and source current detection. The control and implementation of SAPF is being done by instantaneous active and reactive power, PQ theory for the extraction of harmonics from the fundamental and for the generation of Pulses for the voltage source inverter (VSI), space vector pulse width modulation (SVPWM) is used. The harmonics present in the system are computed and the controller generates PWM signals to inject the compensating harmonic current back into the line to cancel the harmonic components in the distorted line. The performance of proposed topology is first examined by MATLAB-SIMLINK-based simulation and the prototype hardware has been developed using DSP TMS320F28027 processor and the results were verified. The Total harmonic distortion (THD) is below the specified limits.

Indirect current controlled shunt active power filter for power quality improvement

The paper deals with an indirect current controlled shunt active power filter (APF) for improving power quality by reactive power compensation and harmonic filtering. The proposed APF is based on a voltage source inverter (VSI). The VSI is controlled by two loops, the voltage control loop and the current control loop. The voltage control loop regulates the DC link capacitor voltage and the current control loop uses hysteresis band control to shape the source current such that it is in-phase with and of the same shape as the input voltage. The major advantage of the proposed APF is that the reference current for power quality improvement is generated from the DC link capacitor voltage. The proposed scheme has been verified through simulation and experimental investigations.

A Source-Current-Detected Shunt Active Power Filter Control Scheme Based on Vector Resonant Controller

A shunt active power filter (APF) with current detection at the source side is considered as a closed-loop system from the view of the whole power distribution system, which is expected with better harmonics filtering performance compared with the one with load current detection. The conventional source current detection control scheme can be mainly grouped into two types: 1) current-source-based (CS) scheme and 2) power-balance-based (PB) scheme. As introduced in this paper, the CS scheme has good dc-voltage regulation, but it bears inevitable conflict between filtering performance and system stability, whereas the PB scheme has excellent stable filtering performance, but it bears great influence on the dc voltage in the transient state. In this paper, a novel source current detection control scheme is proposed, which reserves the advantages of conventional schemes and, meanwhile, avoids their limitations. The proposed scheme employs a vector resonant controller, with which the shunt APF performs as an equivalent multiband rejection filter that series between nonlinear loads and the grid source, blocking selected harmonics components from the load side flowing into the source side. The proposed scheme is simple in structure, is needless of a harmonics extraction algorithm, and shows good stable and transient performance. Finally, the conclusions obtained in this paper are validated through experiments on the laboratory prototype.

Power quality improvement using fuzzy logic controller for five-level shunt active power filter under distorted voltage conditions

In this paper, a five-level inverter is used as a shunt active power filter (APF), taking advantages of the multilevel inverter such as low harmonic distortion and reduced switching losses. It is used to compensate reactive power and eliminate harmonics drawn from a thyristor rectifier feeding an inductive load (RL) under distorted voltage conditions. The APF control strategy is based on the use of self-tuning filters (STF) for reference current generation and a fuzzy logic current controller. The use of STF instead of classical extraction filters allows extracting directly the voltage and current fundamental components in the α-β axis without phase locked loop (PLL). The MATLAB fuzzy logic toolbox is used for implementing the fuzzy logic control algorithm. The obtained results show that the proposed shunt APF controller has produced a sinusoidal supply current with low harmonic distortion and in phase with the line voltage.

Shunt Active Power Filter System Design for Inter-harmonic

Given the complex situations of the grid with inter-harmonics, three-level model of shunt active power filter (SAPF) was built. For the harmonics accurate detection, the CPT principle was used to detect the fundamental component of the grid. The inter-harmonics, parameter fluctuation of APF and the deadband effect were considered as the non-periodic disturbance to the controller. To eliminate the non-periodic disturbance impact on the controller and to improve the control system performance, equivalent input-disturbance (EID) was used based on the traditional repetitive controller. With Matlab and three-level test platform, the SAPF control system was built. The performance of detection and compensation for harmonic and inter-harmonic was verified by the simulation and experiment. DOI: http://dx.doi.org/10.11591/ijpeds.v3i4.4442

Design and Performance of a Three-Phase Fuzzy Logic Controlled Shunt Active Power Filter Control Hardware with a 400 kHz Switching PWM Implemented in FPGA

This paper presents a control strategy for harmonic compensation using a fuzzy logic controlled shunt active power filter generating a 400 kHz PWM control signal compatible with recent Silicon Carbide inverters. The designed controller uses the p-q Theory, a modified Fuzzy DC regulator instead of a PI Fuzzy and high speed current generation for the 400 kHz PWM control signal. This paper also describes and analyzes the improvement in increasing the switching frequency and its relation to the total harmonic distortion at the source and the filter inductors size. Such control presents a complexity in terms of speed which is solved by the use of a FPGA. The FPGA allows the Fuzzy DC controller to operate in parallel with the p-q Theory and the 400 kHz PWM generator, optimizing speed and hardware with the use of VHDL-2008 fixed-point libraries. The controller is synthesized in the Altera Cyclone $$^{\circledR }$$ IV EP4CE115 from DE2-115 board. The implementation is experimentally validated by “FPGA in the Loop” and compared with other similar solutions showing better performance and effectiveness.

Fuzzy logic controller for three-phase four-leg five-level shunt active power filter under unbalanced non-linear load and distorted voltage conditions

This paper presents a five-level inverter which is used as a three-phase four leg shunt active power filter, taking advantages of the multilevel inverter such as low harmonic distortion and reduced switching losses. It is used to suppress harmonic current, compensate reactive power and neutral line current and balance the load currents under unbalanced non-linear load and distorted voltage conditions. The active power filter control is essentially based on the use of self tuning filters for the reference current generation and a fuzzy logic current controller. This study is divided in two parts. The first one deals with the harmonic isolator which generates the harmonic reference currents. The second part focuses on the generation of the switching pattern of the inverter by using a fuzzy logic controller applied and extended to a four leg five level shunt active power filter. The MATLAB Fuzzy Logic Toolbox is used for implementing the fuzzy logic control algorithm. The performance of the proposed shunt active power filter controller is found considerably effective and adequate to compensate harmonics, reactive power and neutral current and balance load currents under distorted voltage conditions.

A new concept of harmonic current detection for shunt active power filters control

The paper deals with measurement and control aspects of active power filtering in ship systems. The main focus of the paper is concentrated on improvement of harmonic current measurement algorithms based on ip–iq method with application of low-pass filter (LPF) module and, alternatively, on ip–iq method with application of mean value module.

Novel Control Strategy for a UPQC under Distorted Source and Nonlinear Load Conditions

This paper proposes a novel control strategy for a unified power quality conditioner (UPQC) including a series and a shunt active power filter (APF) to compensate the harmonics in both the distorted supply voltage and the nonlinear load current. In the series APF control scheme, a proportional-integral (PI) controller and a resonant controller tuned at six multiples of the fundamental frequency of the network (<TEX>$6{\omega}_s$</TEX>) are performed to compensate the harmonics in the distorted source. Meanwhile, a PI controller and three resonant controllers tuned at <TEX>$6n{\omega}_s$</TEX>(n=1, 2, 3) are designed in the shunt APF control scheme to mitigate the harmonic currents produced by nonlinear loads. The performance of the proposed UPQC is significantly improved when compared to that of the conventional control strategy thanks to the effective design of the resonant controllers. The feasibility of the proposed UPQC control scheme is validated through simulation and experimental results.