Coupling Hybrid Active Power Filter Research Articles

Finite-Set Model Predictive Control for Hybrid Active Power Filter

A finite-set model predictive control (FS-MPC) with coupling capacitor voltage observer scheme is proposed for thyristor-controlled <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -coupling hybrid active power filter (TC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -HAPF) in this article. It ensures the fast transient response, low steady-state error, and good robustness under both inductive and capacitive load situations. Generally, the implementation of FS-MPC for TC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -HAPF requires sensing of coupling capacitor voltage and thyristor-controlled reactor current in addition to sensing load voltage, load current, and compensation current, which increases the system complexity and cost. To relax this problem, the simplified predictive model is first proposed, thus reducing the required sensing signals and system order. Then, a coupling capacitor voltage observer is utilized to reduce the hardware costs, which can obtain a comparable performance with directly sensed capacitor voltage. The delay compensation is also considered for the control delay in practical realization. Finally, the effectiveness and performance of the FS-MPC with coupling capacitor voltage observer for TC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -HAPF are verified by simulated and experimental results.

Improved Model Predictive Control With Signal Correction Technique of LC-Coupling Hybrid Active Power Filter

In this article, an improved model predictive control (MPC) with signal correction technique for an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -coupling hybrid active power filter ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -HAPF) is proposed, which can track the reference compensating current with fast dynamic response and low steady-state error. The conventional MPC causes a certain degree of steady-state error due to the error from discretization and prediction. To solve this problem, a signal correction technique is proposed to improve the compensation performance of the MPC for the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -HAPF. First, the model of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -HAPF for implementing the MPC is deduced in this article. Then, the control objective and the design methodology of the improved MPC are presented. After that, the stability and parameter design of the improved MPC is analyzed and discussed. Finally, the compensation performance of the proposed improved MPC for the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -HAPF is verified by simulation and experimental results in comparison with the conventional MPC and other representative current controllers.

H∞ Optimal Control Design of Static Var Compensator Coupling Hybrid Active Power Filter Based on Harmonic State-Space Modeling

Compared with the conventional active power filter (APF), the static var compensator coupling hybrid active power filter (SVC-HAPF) has distinct characteristics of low DC-link operating voltage, which can lower the system and operational costs. It also has a wider operational range than the conventional hybrid active power filter (HAPF). In this paper, a harmonic state-space (HSS) modeling is firstly proposed to address the nonlinearity issue of the SVC-HAPF. The HSS based SVC-HAPF model is linear time-invariant (LTI), which enables the optimal control techniques. Then, the linear matrix inequality (LMI) based H ∞ optimal control design is proposed, which finds the optimal controller parameters via convex optimization algorithm. The proposed controller for the SVC-HAPF achieves high steady-state accuracy, fast transient response, and fixed switching frequency simultaneously. Finally, simulation and experimental results are also provided to verify the effectiveness and performance of the optimal controller for the SVC-HAPF in comparison with the recent developed state-of-the-art multi-quasi-proportional-resonant (MQPR) controller, which shows superior control performances.

Analysis, Design, and Implementation of Multi-Quasi-Proportional-Resonant Controller for Thyristor-ControlledLC-Coupling Hybrid Active Power Filter (TCLC-HAPF)

Compared with the conventional active power filter, the thyristor-controlled <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -coupling hybrid active power filter (TC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -HAPF) has a distinct characteristics of low dc-link operating voltage, which can lower the system and operational costs in the medium-voltage-level system. It also has a wider operational range than the conventional hybrid active power filter. Besides that, the TC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -HAPF can provide reactive, harmonic, and unbalanced powers compensation simultaneously. In this article, the modeling of the TC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -HAPF is investigated based on the linear control aspect. Then, the analysis, design, and implementation of a multi-quasi-proportional-resonant (MQPR) controller with gain scheduling for the TC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -HAPF will be proposed, which can automatically change the resonant gain between the inductive and capacitive loads operation to improve its compensation performances. The proposed controller can significantly reduce the TC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -HAPF steady-state current tracking errors and output current ripple. Finally, the simulation and experimental results are also provided to verify the effectiveness and performance of the MQPR controller for the TC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -HAPF in comparison with the hysteresis current controller and quasi-proportional-resonant (QPR) controller, which shows superior compensating performances.

Design, control and comparative analysis of an LCLC coupling hybrid active power filter

This study provides the design, control and comparative analysis of the proposed LCLC coupling hybrid active power filter (LCLC-HAPF). Compared with the conventional L filter coupling active power filters (APFs), LC filter and LCL filter coupling HAPFs (LC-HAPFs and LCL-HAPFs), the proposed LCLC-HAPF provides better switching frequency harmonics elimination, lower dc-link voltage rating and switching loss. Although the LCLC-HAPF has some advantages, two main challenges will still be confronted in practical implementations. Those are stability problems caused by resonance of LCLC filter, and parameter design for the LCLC filter. In this study, a new active damping method is proposed to overcome the high order resonance problem existing in the proposed LCLC-HAPF. After that, the stability analysis and parameter design are given for the proposed LCLC-HAPF. Finally, the effectiveness of the proposed LCLC-HAPF topology is validated through both simulation and experimental studies in comparison with the conventional APFs and HAPFs.

Second-Order Sliding-Mode Current Controller for LC-Coupling Hybrid Active Power Filter

In this article, a second-order sliding-mode control (SOSMC) based on supertwisting controller for LC -coupling hybrid active power filter ( LC -HAPF) is proposed. Among the literatures review studies, hysteresis-based current controller, which is a special implementation of sliding-mode control, is usually used due to its simplicity, robustness, and good dynamic performance for reference tracking. However, it generates a nonfixed switching frequency for the power filter, which leads to undesirable harmonics problem. The proposed SOSMC ensures the good robustness and dynamic performance of using the conventional sliding mode control with an improved steady-state performance and disturbance rejection capability. In addition, with the help of supertwisting controller, the proposed SOSMC can achieve fixed switching frequency characteristic. First, the control objective and the design methodology of sliding surface are discussed and given in this article. Second, a detailed parameter design procedure under stability, system parameter variation, distorted grid voltage, and grid frequency variation consideration is provided. Then, experimental results on a three-phase four-wire LC -HAPF are carried out to verify the steady-state and dynamic performances of the proposed SOSMC compared with other representative current controllers. Finally, the disturbance rejection capability under different grid conditions of the proposed SOSMC is also verified by experimental results.

A Deadbeat Current Controller of LC-Hybrid Active Power Filter for Power Quality Improvement

In this article, a deadbeat current controller for an LC -coupling hybrid active power filter ( LC -HAPF) is proposed, which can track with the reference compensation current with low steady-state error and fast dynamic response. Moreover, it can lead LC -HAPF to be operating at a fixed switching frequency with low output current ripples, thus reducing the size of the filtering circuit. First of all, the mathematical model of the deadbeat current controller for the LC -HAPF is deduced based on its single-phase equivalent circuit. Then, the closed-loop control block diagram and its $s$ -domain model is proposed and built. After that, 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 LC -HAPF is verified by simulation and experimental results compared with the conventional hysteresis band pulsewidth modulation (PWM) control, the proportional-integral (PI) control, and the proportional multi-resonant (PMR) control for the LC -HAPF, which shows its effectiveness and superior compensating performances.

Unbalanced Control Strategy for A Thyristor-Controlled LC-Coupling Hybrid Active Power Filter in Three-Phase Three-Wire Systems

This paper proposes a control strategy for a three-phase three-wire thyristor-controlled LC -coupling hybrid active power filter (TCLC-HAPF), which can balance active power and compensate reactive power and harmonic currents under unbalanced loading. Compared with TCLC-HAPF with conventional control strategy, active power filters and hybrid active power filters which either fail to perform satisfactory compensation or require high-rating active inverter part for unbalanced compensation, a control strategy was proposed for TCLC-HAPF to operate with a small rating active inverter part for a variety of loads with satisfactory performance. The control idea is to provide different firing angles for each phase of the thyristor-controlled LC -coupling part (TCLC) to balance active power and compensate reactive power, while the active inverter part aims to compensate harmonic currents. First, the required different TCLC impedances are deduced. Then, independent firing angles referenced to the phase angle of voltage across TCLC are calculated. After angle transformations, final firing angles referenced to phase angle of load voltages are obtained. In this paper, a novel controller for TCLC-HAPF under unbalanced loading is proposed. Simulation and experimental results are provided to verify the effectiveness of the proposed controller in comparison with a state-of-the-art controller.

Design and Performance of an Adaptive Low-DC-Voltage-Controlled LC-Hybrid Active Power Filter With a Neutral Inductor in Three-Phase Four-Wire Power Systems

This paper proposes an adaptive low-dc-link-voltage-controlled LC coupling hybrid active power filter ( LC-HAPF) with a neutral inductor, which can compensate both dynamic reactive power and current harmonics in three-phase four-wire distribution power systems. Due to its adaptive low-dc-link-voltage characteristic, it can obtain the least switching loss and switching noise and the best compensating performances, compared with the conventional fixed and newly adaptive dc-voltage-controlled LC-HAPFs. The design procedures of the dc-link voltage controller are discussed, so that the proportional and integral gains can be designed accordingly. Moreover, the general design procedures for the adaptive dc-voltage-controlled LC-HAPF with a neutral inductor are also given. The validity and effectiveness of the adaptive dc-link voltage-controlled LC -HAPF with a neutral inductor are confirmed by experimental results obtained from a 220-V 10-kVA laboratory prototype compared with the conventional fixed and adaptive dc-link voltage-controlled LC-HAPFs without a neutral inductor.

Analysis of DC-Link Voltage Controls in Three-Phase Four-Wire Hybrid Active Power Filters

This paper investigates different dc-link voltage control strategies in a three-phase four-wire LC coupling hybrid active power filter (LC -HAPF) for reactive power compensation. By using direct current (current reference) pulsewidth modulation (PWM) control method, to achieve dc-link voltage self-charging function during LC -HAPF start-up process, the dc-link voltage control signal feedback as reactive current component is more effective than the traditional method as an active current component. However, when the LC-HAPF is performing dynamic reactive power compensation, this dc-link voltage control scheme will influence the reactive power compensation, and thus, makes the LC-HAPF lack of success to carry out dynamic reactive power compensation. In this paper, a novel dc-link voltage control scheme for LC-HAPF is proposed so that the dc-link voltage control with start-up self-charging process can be obtained as well as providing dynamic reactive power compensation. Representative simulation and experimental results of the three-phase four-wire center-spilt LC-HAPF are presented to verify all deductions, and also show the effectiveness of the proposed dc-link voltage control scheme in dynamic reactive power compensation.

Hysteresis current control of hybrid active power filters

This article presents a hysteresis pulse width modulation study for a inductor-capacitor (LC)-coupling hybrid active power filter (HAPF). As the coupling LC impedance yields a non-linear inverter current slope, this can affect the controllability of using the conventional hysteresis control method and generate unexpected trigger signals to the switching devices. This results in deteriorating the system operating performances. On the basis of the proposed modelling, the linearisation of the hysteresis control for the HAPF is firstly studied, investigated and compared with the linear active power filter. Two limits are proposed in this study that divides the HAPF into non-linear, quasi-linear and linear operation regions. The design criteria of hysteresis band and sampling time can then be derived. Single-phase simulation and experimental results are given to verify the hysteresis control study of HAPF compared with active power filter. Finally, representative simulation and experimental results of a three-phase four-wire centre-split HAPF for power quality compensation are presented to demonstrate the validity of the hysteresis linearisation study.

Adaptive DC-Link Voltage-Controlled Hybrid Active Power Filters for Reactive Power Compensation

This paper presents a novel adaptive dc-link voltage-controlled LC coupling hybrid active power filter (LC-HAPF) for reducing switching loss and switching noise under reactive power compensation. First, the mathematical relationship between LC-HAPF dc-link voltage and reactive power compensation range is deduced and presented. Based on the compensation range analysis, the required minimum dc-link voltage with respect to different loading reactive power is deduced. Then, an adaptive dc-link voltage controller for the three-phase four-wire LC-HAPF is proposed, in which the dc-link voltage as well as the reactive power compensation range can be adaptively changed according to different inductive loading situations. Therefore, the compensation range, switching loss, and switching noise of the LC-HAPF can be determined and reduced correspondingly. In this paper, the reference dc-link voltage is classified into certain levels for selection in order to alleviate the problem of dc voltage fluctuation caused by its reference frequent variation, and hence reducing the fluctuation impact on the compensation performances. Finally, representative simulation and experimental results of a three-phase four-wire center-split LC -HAPF are presented to verify the validity and effectiveness of the proposed adaptive dc-link voltage-controlled LC-HAPF in dynamic reactive power compensation.