Single-phase Shunt Active Power Filter Research Articles

Hybrid One-Cycle-PI Control Algorithm for Shunt Active Power Filter in Mitigating Harmonic Currents

The quality of current waveforms, such as the presence of the harmonic components at the point of common coupling of various consumers, deteriorated due to the nonlinear load applications. Hence, a Shunt Active Power Filter (SAPF) is used to mitigate harmonic pollution in an electrical network. The heart of the SAPF operation is the current control technique. The choice of current control techniques significantly impacts the SAPF performance. As a result, a Hybrid One-Cycle-PI Control (HOCPIC) is proposed to work as a single-phase SAPF's current controller. The HOCPIC utilises a Proportional-Integral (PI) controller to minimise the error signal. As a result, the THD value of the supply current is reduced to 3.20% using the SAPF-based HOCPIC compared to 3.99% when using the SAPF-based OCC. The result proves that the SAPF-based HOCPIC performs better in compensating harmonic currents than the SAPF-based OCC.

RF and Shunt Active Power Filters at Multiple Points of Common Couplings of Radial Electrical Systems

This work investigates the effects of RL filters and single-phase Shunt Active Power Filters (SAPFs) on the supply and load current waveforms and their properties. The parameters involved are rms, input Power Factor (PF) and Total Harmonic Distortion (THD). These parameters can describe the quality of any electrical power system, especially PF and THD. This work focuses on implementing both filters in an electrical radial system due to the limited research work. Hence, the effects of utilising both filters in the radial system are studied. In this work, both filters connect at different Points of Common Couplings (PCCs) of a single-phase radial electrical system. The PCCs are located before composite loads (Case 1), before all nonlinear loads (Case 1) and before individual nonlinear loads (Case 3). Both Cases 1 and 2 apply a centralised SAPF, and Case 3 employs individual SAPFs. Matlab/ Simulink simulates all case studies under four operating conditions: (1) without any filters, (2) with SAPFs only, (3) with RL filters only, and (4) with the RL filters and SAPFs. According to the simulation results, the SAPFs require the RF filters to compensate harmonic components effectively. Otherwise, the SAPF’s injection current consists of high current spikes. However, the RF filters may slightly alter the load current waveforms, rms and THD values; the changes are insignificant. Moreover, based on the THD values of the compensated supply current waveform, the centralised SAPFs seem more suitable to be employed in the radial system. By utilising the centralised SAPFs, the THD values of the supply current are lower than using the individual SAPFs. Thus, it can be stated that the centralised SAPFs exhibit better performance. Nevertheless, connecting both filters on the PCCs of all nonlinear loads (Case 2) is suitable to avoid any linear load current waveform deterioration.

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.

Implementation of an Electronically Based Active Power Filter Associated with a Digital Controller for Harmonics Elimination and Power Factor Correction

This paper introduces simulation study and hardware implementation of a shunt active power filter (SAPF). The SAPF is considered an effective method for improving power quality by enhancing the power factor and reducing the total harmonic distortion (THD) for power sources due to nonlinear loads. A digital notch filter is used for extracting the reference current signal. The hysteresis band current controller is used to generate gating switching signals that control the switches of SAPF. The proposed model is constructed using Simulink/MATLAB environment and Proteus VMS, and the performance of the model is tested through a simulation study. The model of SAPF with a digital notch-filter is implemented using the Arduino microcontroller and a printed circuit board (PCB) layout. The model emulating a single-phase SAPF prototype is built and tested in the University of Kafrelshiekh, Faculty of Engineering laboratory. Significant improvements in power quality issues confirm the ability and effectiveness of SAPF, as well as reducing THD to a level less than 5%, which is in proportion to IEEE Std. 519-1992 and IEEE Std. 519-2014. The results emphasize the importance of SAPF to mitigate harmonics problems and enhance power factors.

A Novel Single-Phase Shunt Active Power Filter with a Cost Function Based Model Predictive Current Control Technique

For a single-phase Shunt Active Power Filter (SAPF) with a two-step prediction, this research presents a modified current control based on a Model Predictive Current Control (MPCC) technique. An H-bridge inverter, a DC link capacitor, and a filter inductor comprise the single-phase SAPF topology. The SAPF reference current is computed using the DC-link capacitor voltage regulation-based PI control technique. The weighting factor-based model predictive current controller is used to track the current commands. The essential dynamic index for evaluating waveform quality is the Total Harmonic Distortion (THD) of a source current and switching frequency of power switches. The conventional methods the THD and switching frequency are not considered as an objective function, so that a weighting factor-based MPCC technique is used to obtain a good compromise between the THD of the source current and switching frequency of power switches. Through MATLAB simulation and experimentation with the Cyclone-IV EP4CE30F484 FPGA board, the usefulness of the proposed control technique is proven. As compared with hysteresis, predictive PWM, and conventional MPCC control methods, the cost function-based MPCC algorithm provides a lower switching frequency (13.4 kHz) with an optimal source current THD value.

Novel Neural Network Fractional-Order Sliding-Mode Control With Application to Active Power Filter

In this article, a fractional-order sliding-mode control scheme based on a two-hidden-layer recurrent neural network (THLRNN) is proposed for a single-phase shunt active power filter. Considering the shortcomings of traditional neural networks (NNs) that the approximation accuracy is not high and weight and center vector of NNs are unchangeable, a new THLRNN structure which contains two hidden layers to make the network have more powerful fitting ability, is designed to approximate the unknown nonlinearities. A fractional-order term is added to a sliding-mode controller to have more adjustable space and better optimization space. Simulation and experimental studies prove that the proposed THLRNN strategy can accomplish the current compensation well with acceptable current tracking error, and have satisfactory compensation property and robustness compared with a traditional neural sliding controller.

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

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

Advanced Control and Observation of Shunt Active Power Filter Connected to PV System

We consider the problem of controlling single-phase shunt active power filter operating in presence of nonlinear loads. The filter is connected to PV system; this latter provides the active power to load. The main control objectives are: (i) compensation of harmonics current and the reactive power caused by the nonlinear load; (ii) regulation of the output voltage of PV system to track its reference provided by the MPPT block. The problem is dealt with a nonlinear controller involving two regulators in cascade. The PFC regulator is developed by using the Lyapunov technique to cope with the compensation issue based on the estimated grid voltage values provided by an observer. The outer-loop regulates the output voltage of PV system. The proposed controller performances are confirmed by simulation in MATLAB\\Simulink.

Experimental Evaluation of Single-Phase Shunt Active Power Filter Based on Optimized Synergetic Control Strategy for Power Quality Enhancement

In this paper, a synergetic approach based on particle swarm optimization (SC-PSO) technique is proposed for Single-Phase Shunt Active Power Filter (SP-SAPF). Two-loop cascade controller for SP-SAPF has been designed. In the first loop, a PI controller is used to effectively regulate the DC link voltage. In the second one, a synergetic controller is performed in the current compensation control loop. The various adjustable parameters of the studied synergetic controller are tuned by a PSO algorithm. The objective of this adjustment is to get the optimal control parameters for satisfying requirements of power quality and high dynamic responses for SP-SAPF. The effectiveness of the suggested SC-PSO approach has been proved by simulation and experimental tests using MATLAB/Simulink environment and dSPACE 1104 card for several operating conditions. The experimental results demonstrate that the developed SC-PSO approach is very satisfactory and offers a high performance for both transient and steady states.

Using Nonlinear Load DC Variables as Inputs for Harmonic Current Reduction

This paper introduces and discusses new inputs for a single-phase shunt active power filter (SAPF) using nonlinear load equivalent resistance estimation control strategy. The inputs are an average DC voltage and current of a current source nonlinear load. By using a MATLAB Simulink simulation tool, a model of single-phase AC system connected to the SAPF and nonlinear load is designed and its vital voltage and current variables are simulated. Various simulation results are presented and analysed in order to validate the effectiveness of proposed inputs. As a conclusion, the proposed control strategy with new inputs successfully achieved its objective to mitigate harmonic current and to compensate the reactive power with good performance.

A modified indirect extraction method for a single-phase shunt active power filter with smaller DC-link capacitor size

Indirect extraction method is the most common method to control the single-phase active power filters (APFs) due to its simple structure. The main drawback of this extraction method is its performance dependency on the quality of the DC-link voltage. Selecting the high capacity of the DC-link capacitor leads to the high cost and size of APF, weak dynamic response and low-even-order harmonic components on the DC-link voltage. The low capacity of the DC-link capacitor decreases the cost and size of APF, decreases the sub-harmonics and inter-harmonics of the DC-link voltage, improves the dynamic response, and increases the even-order voltage harmonics. This paper proposes a new extraction method to improve the performance of the conventional indirect extraction method. The proposed method uses a small size of capacitor to achieve the aforementioned advantages. The even-order voltage harmonics are eliminated by the single-frequency-decoupled (SFD) scheme. For implementation of the SFD scheme, the proposed method uses proportional-resonant (PR) controllers, and second order generation integrator-frequency locked loop (SOGI-FLL). The effectiveness of the proposed extraction method is verified by the simulation and experiment.

Synchronous Reference Frame with Finite Impulse Response Filter for Operation of Single-phase Shunt Active Power Filter

Power Quality (PQ) has been recognized as one of the main issues in electricity supply worldwide after the invention of nonlinear load. In 2017, PQ problem leads to significant economic losses in the Pan European region. Therefore, Active Power Filter has been developed during the past two decades to improve the harmonic compensation, reactive power, and voltage balance. In this research, the evaluation of the Synchronous Reference Frame (SRF) method is done under nonlinear load condition. The objective of this research is to modify the harmonic extraction algorithm based on SRF concepts for the application of single-phase shunt active power filter (SAPF) in harmonics mitigation and evaluate the performance of it. The performance of the SAPF that used SRF is evaluated and verified using MATLAB/Simulink. Besides that, the proposed SRF will be benchmarked with several existing techniques. The results are verified using MATLAB/Simulink with the aid of Powergui in the SimPower System block. Powergui has a built in Fast Fourier Transform (FFT) analysis tool that could perform harmonic analysis. With the aid of this tool, the Total Harmonic Distortion (THD) value can be viewed in the block. This research does achieve the THD value of the power system keeps under the limit set by IEEE standard 519.

Adaptive Sliding Mode Long Short-Term Memory Fuzzy Neural Control for Harmonic Suppression

In this paper, an adaptive sliding mode controller based on a long and short-term memory fuzzy neural network (ASMC-LSTMFNN) is proposed to suppress harmonics for an active power filter (APF). Firstly, a mathematical dynamic model of a single-phase shunt active power filter considering lumped uncertainties is introduced. Then, based on the design of conventional sliding mode control (SMC), a new type of long and short-term memory fuzzy neural network (LSTMFNN) is proposed to approximate the unknown function of the system. The LSTMFNN incorporates a fuzzy neural network (FNN) structure and long and short-term memory (LSTM) mechanism, excellent learning ability and approximation performance. Moreover, the parameters of the neural network are all automatically adjusted through the adaptive laws, and the Lyapunov stability theorem guarantees the current tracking performance and the stability of the closed-loop system. Finally, hardware experiments are carried out based on the dSPACE hardware platform, and the experimental results show that it has good steady-state and dynamic performance, verifying that it has better control performance and harmonic compensation ability compared with the adaptive sliding mode control based on recurrent fuzzy neural network (ASMC-RFNN).

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

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

An Improved Reference Current Generation and Digital Deadbeat Controller for Single-Phase Shunt Active Power Filters

This paper proposes an improved reference current generation and digital deadbeat current controller for single-phase shunt active power filters. The main advantages of the suggested control technique are simplicity, fast dynamics, low computational burden, high accuracy, and direct digital implementation. A straightforward modelling of system and design procedure is described in this paper. The stability analysis of the current control system, especially under parameter uncertainties, is studied. Also, a comprehensive comparison between the proposed technique and the conventional deadbeat controller is provided. In order to generate the reference compensating current, a second order generalized integrator-based PQ technique is used and the effect of integrator discretization in terms of dynamic response, accuracy and real-time computational burden is investigated. Simulation and experimental results on a real prototype system under steady-state and transients are reported to demonstrate the validity of theoretical analyses.

Backstepping Controller With Dual Self-Tuning Filter for Single-Phase Shunt Active Power Filters Under Distorted Grid Voltage Condition

This article presents the design and hardware implementation of an adaptive nonlinear controller for fast, robust, and stable control of single-phase shunt active power filter. The proposed control system consists of two control loops: an inner harmonic current compensation loop and an outer dc-voltage control loop. The inner loop is realized using self tuning filter based instantaneous power theory (pq theory). The limitations of conventional low-pass filter based fundamental component extraction methods are overcome using self-tuning filter. The outer loop is realized backstepping controller (BSC). The limitations observed in existing dc-link voltage controllers like poor stability margin, steady state error, chattering problem, etc., are overcome by the proposed BSC. The switching loss estimation is introduced in BSC using design estimation rules to enhance the dc-link loss compensation capability. The stability of the system with the proposed controller is studied using Barbalat lemma. A laboratory prototype of BSC based shunt active power filter is implemented. The control algorithm is implemented in a single all on chip field programmable gate array (FPGA). To ensure the effectiveness of the controller in mitigating the harmonic currents and controlling dc-link voltage, the control algorithm is tested under steady state and dynamic conditions.

Optimal design of a single-phase APF based on PQ theory

The instantaneous active and reactive power (PQ) theory is one of the most widely used control theory for shunt active power filter (SAPF), which can be implemented in single-phase and three-phase systems. However, the SAPF with PQ theory still had ability to improve to become more efficient. This paper presents the optimal design of a single-phase SAPF in terms of reducing the current harmonic distortion and power loss in voltage source inverter (VSI) controlled with the semiconductor switching devices IGBT, MOSFET and Hybrid (combination of IGBT and MOSFET). In order to reduce the switching frequency and power loss of VSI, instead of using single-band hysteresis current controller (HCC), double-band HCC (DHCC) and triple-band HCC (THCC) is used in the SAPF. The designed SAPF is tested with different non-linear loads to verify the results by using MATLAB Simulink.

Real Time Implementation and Analysis of Enhanced Artificial Bee Colony Algorithm Optimized PI Control algorithm for Single Phase Shunt Active Power Filter

This paper proposes a new hybrid novel optimization approach, called Enhanced Artificial Bee Colony Algorithm (EABC) for designing an optimal PI controller for single-phase Shunt Active Power Filter (SAPF). The proposed EABC algorithm optimizes the gain values of the PI controller to improve the dynamic performance of SAPF. In this EABC, the adaptive real coded genetic algorithm (ARGA) is integrated with the Artificial Bee Colony (ABC) algorithm and this integration improves the exploration and exploitation ABC and speed up the convergence rate. The minimization of integral square error (ISE) is considered as an objective function to manipulate the gain values of the PI controller. The system tested with MATLAB simulation results are implemented in the hardware circuit with the same set of parameters. The proposed hardware system is designed with the Cyclone-IV EP4CE30F484 FPGA controller and the gain value for this proposed controller is fed from the simulation results tested with ABC and EABC algorithm. The results obtained from the hardware setup is compared with simulation results. The experimental result enhanced the performance of THD of source current, settling time and percentage peak overshoot of DC Link voltage.

Double-Hidden-Layer Recurrent Neural Network Fractional-Order Sliding Mode Control of Shunt Active Power Filter

In this paper, a fractional-order sliding mode control scheme based on a double-hidden-layer recurrent neural network is proposed for a single-phase shunt active power filter. Considering the shortcomings of traditional neural networks that the approximation accuracy is not high and weight and center vector of neural networks are unchangeable, a new double-hidden-layer recurrent neural network structure which contains two hidden layers to make the network have more powerful fitting ability, is designed to approximate the unknown nonlinearities. An original output feedback neural network with two hidden layers is designed to estimate the uncertainties regardless of unknown system characteristics and external disturbances. A fractional-order term is added to the sliding mode controller to have more adjustable space and better optimization space. Experimental results verified the validity of the designed controller and proved that it can complete the current compensation well with acceptable current tracking error, demonstrating the outstanding compensation performance and strong robustness

Sensorless Nonlinear Control Strategy of the Single Phase Active Power Filters via Two-time Scale Singular Perturbation Technique

This paper focuses on the problem of controlling single-phase shunt active power filters (APFs) operating in the presence of nonlinear and uncertain loads. The main difficulties when controlling this kind of filter are the existence of a strong non-linearity of the system and state variables inaccessible to measurements. This paper proposes a double-loop cascade controller developed on the basis of the singular perturbation technique in order to meet two main control objectives: (i) the inner-loop is designed to compensate the harmonic and reactive currents absorbed by the nonlinear load enforcing power factor correction; (ii) the outer-loop is synthesized to regulate the inverter output capacitor voltage. The controller also includes two-time scale sliding mode observer to estimate the network voltage that is not accessible to measurement. In this work, the singular perturbation technique and averaging theory are used for a complete and rigorous formal analysis to describe the control system performances. The effectiveness of this approach has been successfully verified through computer simulations using the Matlab/Simulink environment.