Three-phase Active Power Filter Research Articles

Finite set model predictive control to a shunt multilevel active filter

Purpose – The purpose of this paper is to implement a finite set model predictive control algorithm to a shunt (or parallel), multilevel (cascaded H-bridge) active power filter (APF). Specifically, the purpose is to get a controller that could compensate the mains current and, at the same time, to control the voltages of its capacitors. This strategy avoids the use of multiple PWM carriers or another type of special modulator, and requires a relatively low processing power. Design/methodology/approach – This paper is focussed in the application of the predictive controller to a single-phase parallel APF composed for two H-bridges connected in series. The same methodology can be applied to a three-phase APF. In the DC buses of each H-bridge, a floating capacitor was connected, whose voltage is regulated by the predictive controller. The controller is composed by, first, a model for the charge/discharge dynamics for each floating capacitor and a model for the output current of the APF; second, a cost function; and third, an optimization algorithm that is able to control all these variables at the same time, choosing in each sample period the best combination of firing pulses. Findings – The controller can track the voltage references, compensate the current harmonics and compensate reactive power with an algorithm that evaluates only the three nearest voltage levels to the last voltage level applied in the inverter. This strategy decreases the number of calculations required by the predictive algorithm. This controller can be applied to the general case of a single-phase multilevel APF of N-levels and extend it to the three-phase case without major problems. Research limitations/implications – The implemented controller, when the authors consider a constant sample time, gives a mains current with a Total Harmonic Distortion (THD-I) slightly greater in comparison with the base algorithm (that evaluates all the voltage levels). However, when the authors consider the processing times under the same processor, the implemented algorithm requires less time to get the optimal values, can get lower sampling times and then a best performance in terms of THD-I. To implement the controller in a three-phase APF, a faster Digital Signal Processor would be required. Originality/value – The implemented solution uses a model for the charge/discharge of the capacitors and for the filter current that enable to operate the cascaded multilevel inverter with asymmetrical voltages while compensates the mains currents, with a predictive algorithm that requires a relatively low amount of calculations.

三相電力用アクティブフィルタの直流コンデンサ電圧変動の過渡解析と抑制

三相電力用アクティブフィルタの直流コンデンサ電圧変動の過渡解析と抑制

Control for the Three-Phase Four-Wire Four-Leg APF Based on SVPWM and Average Current Method

A novel control method is proposed for the three-phase four-wire four-leg active power filter (APF) to realize the accurate and real-time compensation of harmonic of power system, which combines space vector pulse width modulation (SVPWM) with triangle modulation strategy. Firstly, the basic principle of the APF is briefly described. Then the harmonic and reactive currents are derived by the instantaneous reactive power theory. Finally simulation and experiment are built to verify the validity and effectiveness of the proposed method. The simulation results show that the response time for compensation is about 0.025 sec and the total harmonic distortion (THD) of the source current of phaseAis reduced from 33.38% before compensation to 3.05% with APF.

Development of Shunt-Type Three-Phase Active Power Filter with Novel Adaptive Control for Wind Generators.

This paper proposes a new adaptive filter for wind generators that combines instantaneous reactive power compensation technology and current prediction controller, and therefore this system is characterized by low harmonic distortion, high power factor, and small DC-link voltage variations during load disturbances. The performance of the system was first simulated using MATLAB/Simulink, and the possibility of an adaptive digital low-pass filter eliminating current harmonics was confirmed in steady and transient states. Subsequently, a digital signal processor was used to implement an active power filter. The experimental results indicate, that for the rated operation of 2 kVA, the system has a total harmonic distortion of current less than 5.0% and a power factor of 1.0 on the utility side. Thus, the transient performance of the adaptive filter is superior to the traditional digital low-pass filter and is more economical because of its short computation time compared with other types of adaptive filters.

Experimental Verification of Photovoltaic-based Three-phase Four-wire Series Hybrid Active Power Filter

—This article proposes a photovoltaic and battery interfaced series hybrid active power filter, which is comprised of a series active power filter and an inductor-capacitor (LC) shunt passive filter. The main benefits of the proposed system provide the compensation against the voltage harmonics, current harmonics, and voltage interruption for the whole day. A series active power filter demands a source of energy for compensating the voltage sag/swell. The proposed topology utilizes the green energy source with an energy storage unit to meet the DC-link voltage requirement of the series active power filter. The control strategy is based on the dual formulation of the compensation system principles with adaptive fuzzy logic controller. The simulation and experimental studies are carried out to validate the effectiveness of the proposed photovoltaic interfaced three-phase four-wire series hybrid active power filter.

Adaptive DC-link Voltage Control for Shunt Active Power Filter

This study analyzes the mathematical relationship between DC-link voltage and system parameters for shunt active power filters (APFs). Analysis and mathematical deduction are used to determine the required minimum DC-link voltage for APF. A novel adaptive DC-link voltage controller for the three-phase four-wire shunt APF is then proposed. In this controller, the DC-link voltage reference value will be maintained at the required minimum voltage level. Therefore, power consumption and switching loss will effectively decrease. The DC-link voltage can also adaptively yield different DC-link voltage levels based on different harmonic currents and grid voltage levels and thus avoid the effects of harmonic current and grid voltage fluctuation on compensation performance. Finally, representative simulation and experimental results in a three-phase four-wire center-split shunt APF are presented to verify the validity and effectiveness of the minimum DC-link voltage design and the proposed adaptive DC-link voltage controller.

Research on Saturation Switched Control of Three-Phase Active Power Filter Based on State Feedback Model the Content

The main difficulties in controlling Three-phase active power filter (APF) arise from their hybrid nature, and the saturation of nonlinear constraints. A novel approach to the modeling and regulation problem of APF is presented from the combined perspective of switched system and stability of systems with saturation constraints. Firstly, the three-phase APF is built as switched affine system model. Based on the sufficient condition for quadratic stability of convex combination, the common Lyapunov function was selected. Meanwhile, the switched rules are put forward by this function. The paper also discusses the problem of feedback control for the switched systems with saturated nonlinear constraint; and gives a stability condition for switched system under state saturation. Finally, simulation results have good agreement with the theory analysis, and demonstrate the validity of this approach.

THE ANALYSIS OF ENERGY PROCESSES IN THREE-PHASE ACTIVE POWER FILTER USING SPECTRAL MODELING

The problem of electricity quality to consumers with non-linear, variable load caused the development of technical solutions as a managed device controlled filtering compensates - active power filter is discussed. In known scientific papers the issues of energy redistribution in the power circuit filter elements are clarified. The purpose of this paper is to give analysis of energy processes in a three-phase active power filter using spectral modeling with the presence of poly harmonics mode settings. Based on existing models of active rectifiers the spectral model of the active power filter is developed. For certain conditions for static mode the temporal and spectral dependence of power and energy in the circuit elements is obtained. Analysis of the results revealed that the contours of the device circulating components of high-power compared with the basic harmonic, that circulates between the network and the device, and the fundamental harmonic is absent in the spectrum of the power capacitor. Operation device provides the energy redistribution between phases of the network due to its partial reswitching of reactive elements

An improved deadbeat control algorithm for three-phase four-leg shunt active power filter

ABSTRACTConsidering the influence of the alternating current side resistor, this paper completes the mathematical model for the three-phase four-leg active power filter and deduces the discrete model of the deadbeat control. A novel delay compensation method is proposed to improve the deadbeat control algorithm. Comparing with the algorithm without delay compensation, the proposed algorithm can effectively reduce the delays caused by digital computing and pulse width modulation output. This is achieved by increasing thë sampling and processing frequency without estimating the actual values. The predictive algorithms are also analysed in this paper. For the improved algorithm, the simulation and experimental results show that the total harmonic distortion values of three-phase source currents become lower and the neutral current becomes smaller than the algorithm without delay compensation. Therefore the proposed algorithm can solve the harmonic and unbalancing problems effectively.

Advanced nonlinear control of three phase series active power filter

The problem of controlling three-phase series active power filter (TPSAPF) is addressed in this paper in presence of the perturbations in the voltages of the electrical supply network. The control objective of the TPSAPF is twofold: (i) compensation of all voltage perturbations (voltage harmonics, voltage unbalance and voltage sags), (ii) regulation of the DC bus voltage of the inverter. A controller formed by two nonlinear regulators is designed, using the Backstepping technique, to provide the above compensation. The regulation of the DC bus voltage of the inverter is ensured by the use of a diode bridge rectifier which its output is in parallel with the DC bus capacitor. The Analysis of controller performances is illustrated by numerical simulation in Matlab/Simulink environment.

DC-Bus Voltage Control Strategy Based on Low-Pass Filter for Three-Phase Four-Wire APF

The DC-bus voltage control is critical for stable operation of the three-phase four-wire Active Power Filter. DC-bus stable voltage loop and balance voltage loop are established based on the small signal model. Considering the disadvantages of the traditional PI control, second-order low-pass filter is introduced into the proposed controller. Simulation and experimental results are conducted to validate the effectiveness of the proposed strategy.

Dynamic Behavior of Current Controllers for Selective Harmonic Compensation in Three-Phase Active Power Filters

Current regulators are a critical part of active power filters (APFs). The design of current regulators capable of compensating high-frequency harmonics created by nonlinear loads is a challenging task. Selective harmonic current compensation using harmonic regulators is a viable method to achieve this goal. However, their design and tuning is not an easy task. The performance-and even the stability-of harmonic current regulators strongly depends on implementation issues, with the tuning of the controller gains being critical. Furthermore, the presence of multiple current regulators working in parallel can create unwanted couplings with the fundamental current regulator, which can result in a deterioration of APF current control, i.e., oscillations and settling times larger than expected. This paper addresses the design and tuning of selective harmonic compensators, with a focus on their stability analysis and transient behavior.

Adaptive fuzzy-sliding control with fuzzy-sliding switching for three-phase active power filter

In this paper, an adaptive fuzzy-sliding control system is proposed to improve the dynamic performance of a three-phase active power filter (APF). Adaptive fuzzy controllers are employed to approximate both the equivalent control term and the switching control term in the sliding mode controller. An online adaptive tuning algorithm for the consequent parameters in the fuzzy rules is also designed. The switching control becomes continuous and the chattering phenomena can be attenuated. Simulation demonstrated that the proposed control method has an excellent dynamic performance such as small current tracking error, reduced total harmonic distortion (THD), strong robustness in the presence of parameter variation and non-linear load.

Boost‐type inverter‐less shunt active power filter for VAR and harmonic compensation

Harmonics in power system caused by non-linear loads degrade the power quality. As a result, shunt active power filters are widely applied to deal with current harmonics and poor power factor. However, the traditional voltage-source inverter-based active filters, which usually employ large electrolytic capacitors as the energy-storage elements, cannot get much market penetration. An emerging technique that adopts the direct AC–AC conversion and even harmonic modulation can help to eliminate the bulky energy-storage elements while realising the harmonic compensation and power factor correction functions. A three-phase three-wire boost-type inverter-less active power filter for power factor correction and harmonic compensation is presented. The proposed solution eliminates the bulky electrolytic capacitors. Meanwhile, smaller amount of AC capacitors are needed compared with the buck-type AC–AC converters. Furthermore, continuous grid-side current is obtained, which implies that no extra grid-side filters are needed. Numerical calculation is applied to build the model, and the closed-loop control algorithm employing the synchronous reference frame for power factor correction and multi-harmonics compensation is also developed. The proposed topology and control algorithm is simulated in MATLAB/Simulink and validated with a 15 kVA experimental prototype.

Variable parameter pulse width modulation‐based current tracking technology applied to four‐switch three‐phase shunt active power filter

A novel configuration is proposed with a y/y step-up transformer adding to AC side of the four-switch three-phase (FSTP) active power filter (APF), so as to improve the utilisation of DC voltage and further widen the voltage range of FSTP APF. To ameliorate the current tracking performance of the FSTP inverter, a variable parameter pulse width modulation (VPPWM) approach is presented. In the proposed VPPWM method, the triangular wave is not fixed but derived by integration of reference current error signals. A pulse width coefficient T is also adopted in VPPWM together with the parameter k, so as to make the APF current tracking width adjustable and the resultant over-high switch frequency issue is effectively compromised. The principle and implementation of the VPPWM approach are elucidated in detail, and the validity is demonstrated by simulation studies. The simulation results are compared with that of the proportional-integral control triangular wave comparison approach and the current hysteresis tracking approach, which indicates that the VPPWM methodology shows superior performance in response speed and accuracy to the other ones.

Modeling and State Feedback Control of Three-Phase Active Power Filter on Switched System

Three-phase active power filter (APF) is a typical switched affine system for the action of the power switch. The conventional method of modeling was based on the linear system theory. In this paper, a novel control procedure for the three-phase APF based on the switched affine system and quadratic stability is proposed. Firstly, the three-phase APF is built as switched affine system model. Based on the sufficient condition for quadratic stability of convex combination, the common Lyapunov function is selected. Then, the switched rules can be defined to assess quadratic stability of the switched system, thus realizing the control of the compensation current and the DC side voltage. Finally, simulation results have good agreement with the theory analysis, and demonstrate the validity of this approach.

Adaptive Neural Sliding Mode Control of Active Power Filter

A radial basis function (RBF) neural network adaptive sliding mode control system is developed for the current compensation control of three-phase active power filter (APF). The advantages of the adaptive control, neural network control, and sliding mode control are combined together to achieve the control task; that is, the harmonic current of nonlinear load can be eliminated and the quality of power system can be well improved. Sliding surface coordinate function and sliding mode controller are used as input and output of the RBF neural network, respectively. The neural network control parameters are online adjusted through gradient method and Lyapunov theory. Simulation results demonstrate that the adaptive RBF sliding mode control can compensate harmonic current effectively and has strong robustness to disturbance signals.

Adaptive RBF Neural Network Control for Three-Phase Active Power Filter

Abstract An adaptive radial basis function (RBF) neural network control system for three-phase active power filter (APF) is proposed to eliminate harmonics. Compensation current is generated to track command current so as to eliminate the harmonic current of non-linear load and improve the quality of the power system. The asymptotical stability of the APF system can be guaranteed with the proposed adaptive neural network strategy. The parameters of the neural network can be adaptively updated to achieve the desired tracking task. The simulation results demonstrate good performance, for example showing small current tracking error, reduced total harmonic distortion (THD), improved accuracy and strong robustness in the presence of parameters variation and nonlinear load. It is shown that the adaptive RBF neural network control system for three-phase APF gives better control than hysteresis control.

Parameters Optimization Design of Four-Switch Three-Phase Shunt Active Power Filter

The working capability and cost of four-switch three-phase (FSTP) shunt active power filter (APF) are determined by the parameter selection. Based on mathematical model of FSTP inverter, the effect of key parameters, such as dc-bus voltage level and capacitor voltage transform is analyzed. On account of ac output filter inductance, voltage and capacitance on dc side, output filter in the design of four-switch three-phase APF, this paper expounds the optimal selection approach of parameters, sets up simulation model in PSIM, correctness of the method is verified by simulation on the basis of analysis about law of effect.

Internal Model Control of Three-Phase Four-Leg Active Power Filter Based on Online LS-SVM ANN Inverse System Method

In dealing with the problem of the SAPF’s nonlinear and strong coupling model, the internal model control of three-phase four-leg active power filter based on online ANN method is studied in this paper. With the ANN’s nonlinear mapping ability of self-learning and self-organizing modeling, the inverse system can be approximated by online LS-SVM. In order to have a good linearization control effect, the internal model control based on ANN is proposed for the combined pseudo-linear system. This method can be used to design effective controllers for nonlinear system with unknown mathematical models. At last, the simulation results show that a good steady-state performance can be obtained under the improved method