Digital Repetitive Control of a Three-Phase Four-Wire Shunt Active Filter

Shunt active power filters have been proved as useful elements to correct distorted currents caused by nonlinear loads in power distribution systems. This paper presents an all-digital approach based on a particular repetitive control technique for their control. Specifically, a digital repetitive plug-in controller for odd-harmonic discrete-time periodic references and disturbances is used for the current control loops of the active filter. This approach does not introduce a high gain at those frequencies for which it is not needed and, thus, improves robustness of the controlled system. The active power balance of the whole system is assured by an outer control loop, which is designed from an energy-balancing perspective. The design is performed for a three-phase four-wire shunt active filter with a full-bridge boost topology. Several experimental results are also presented to show the good behavior of the closed-loop system     

三相四线制无功与谐波全补偿的并联有源电力滤波器的研究

简要分析了并联有源电力滤波器的工作原理，选取含有裂相电容的三桥臂电压源型逆变器作为系统主电路，输出电流采用动态滞环控制。针对三相四线系统，且考虑到电网电压畸变和不对称的情况，给出了一种基于瞬时功率理论实现无功功率和谐波全补偿的控制策略，并使用Matlab对系统进行了仿真。     

三相四线制无功与谐波全补偿的并联有源电力滤波器的研究

简要分析了并联有源电力滤波器的工作原理,选取含有裂相电容的三桥臂电压源型逆变器作为系统主电路,输出电流采用动态滞环控制。针对三相四线系统,且考虑到电网电压畸变和不对称的情况,给出了一种基于瞬时功率理论实现无功功率和谐波全补偿的控制策略,并使用Matlab对系统进行了仿真。     

电容中点式有源电力滤波器数学模型及电流复合控制策略

三相四线并联型有源电力滤波器通常可用来补偿非线性负载所引起的谐波和无功电流,以及负载不平衡引起的负序或零序电流。本文描述了电容中点型三相四线有源电力滤波器在abc及dq0坐标系下的数学摸型,并由此给出了dq0同步旋转坐标系下的一种系统控制策略。由于有源电力滤波器指令为快速变化的交流谐波信号,传统的PI控制由于带宽有限,稳态精度较差。因此,提出了基于PI控制和重复控制并联的电流复合控制策略,利用重复控制对于周期扰动信号无差跟踪的特点来提高稳态精度,同时,PI控制又能保证良好的动态性能。仿真和实验结果验证该控制策略的可行性和有效性。     

DSP-Based Implementation of an LQR With Integral Action for a Three-Phase Three-Wire Shunt Active Power Filter

This paper presents the design and implementation of a Linear Quadratic Regulator (LQR) with Integral action (LQRI) for a three-phase three-wire shunt active filter (SAF). The integral action is added so as to cancel the steady-state errors for reference tracking or disturbance rejection, knowing that the standard LQR provides only proportional gains. The controller is designed to achieve dc bus voltage regulation and harmonics and reactive power compensation. The converter model is set in the $d{-}q$ rotating reference frame. The latter is augmented with the integral of the $q$ component of the SAF currents and dc bus voltage to achieve integral action. The controller's performance depends on the weighting matrix, which is chosen to ensure satisfactory response. The converter is controlled as a whole, i.e., a multi-input–multioutput system and a fixed pulsewidth modulation at 10 kHz is used to generate the gating signals of the power devices. The system is tested for harmonics, reactive power, and load unbalance compensation for balanced/unbalanced loads. The experimental results obtained with a digital signal processor-based implementation of the controller on the DS1104 of dSPACE show good performance in terms of dc bus voltage regulation (small overshoot and very fast time response) and a low total harmonic distortion of ac line currents.      

三相四线制有源电力滤波器的设计与仿真

三相四线制有源电力滤波器能够很好地提高滤波器的滤波性能,实现在大功率场合下的谐波抑制和无功补偿。通过研究主电路拓扑结构,给出了主电路设计方法,包括触发电路的设计,IPM驱动电路的设计和同步信号电路的设计。综合运用瞬时无功理论中的p-q法和ip—iq法,提出了一种新的基于瞬时无功理论的有效的三相四线制谐波检测新方法,此方法能将三相电流中的零序电流剔除。最后文章利用Matlab／Simulink构建了仿真模型,设定了仿真模型中各部分的参数,仿真结果验证了该方法的准确性和有效性。     

并联型三相有源滤波器谐波电流检测研究

在有源滤波器设计中,谐波电流的实时检测与分离是其中的关键环节。文中分析了基于瞬时无功理论的ip、iq法检测谐波电流的基本原理与实现方法。ipi、q法与DFT谐波电流检测方法相比,实时性能更好,容易实现,而且不受电网电压波形畸变的影响。仿真和实验表明,采用ipi、q法能够实时、准确地检测出非线性负载的谐波电流和无功电流。     

A Model-Based Controller for A Three-Phase Four-Wire Shunt Active Filter With Compensation of the Neutral Line Current

This paper presents a model-based controller for a three-phase four-wire shunt active filter, which uses a three-leg split-capacitor topology to implement the voltage source inverter. The controller is aimed to compensate reactive power and harmonic distortion in the general case of distorted and unbalanced source voltages and load currents, including distorted loads connected between a phase and the neutral line. In addition, the controller is able to compensate for the homopolar component of the load current, that is, the current flowing to the source via the neutral line can be considerably reduced without modifying the actual topology. The complete model in (fixed frame) alphabetagamma-coordinates is presented. Special attention is given to the homopolar component (referred here as the gamma-component) of the line current, source voltage and control input, which are instrumental for the control design purpose. Experimental results in a 2 kVA prototype are provided to illustrate the benefits of the proposed solution.     

瞬时无功理论在三相四线SAPF中的应用研究

本文借助于对称分量法分析和证明了瞬时无功理论方法在三相四线并联有源电力滤波器（SAPF）中的适用性，然后就电网电压发生畸变对SAPF的影响进行了讨论，最后从仿真和实验两方面证明了以上分析的正确性。     

Seven-Level Shunt Active Power Filter for High-Power Drive Systems

In high-power adjustable-speed motor drives, such as those used in electric ship propulsion systems, active filters provide a viable solution to mitigating harmonic related issues caused by diode or thyristor rectifier front-ends. To handle the large compensation currents and provide better thermal management, two or more paralleled semiconductor switching devices can be used. In this paper, a novel topology is proposed where two active filter inverters are connected with tapped reactors to share the compensation currents. The proposed active filter topology can also produce seven voltage levels, which significantly reduces the switching current ripple and the size of passive components. Based on the joint redundant state selection strategy, a current balancing algorithm is proposed to keep the reactor magnetizing current to a minimum. It is shown through simulation that the proposed active filter can achieve high overall system performance. The system is also implemented on a real-time digital simulator to further verify its effectiveness.      

基于三相并联混合有源滤波器的直接功率控制理论

文中研究的目的是使并联混合型有源电力滤波器取得更好的性价比。由于大功率的电力电子器件（GTO／IGCT）不能应用在高于10kHz,电流控制综合使用了同步参考坐标（SRF）和瞬时无功功率（IRP）的直接功率控制方法,而且IRP的矢量算法没有使用变换矩阵。这种方法的可行性用MATLAB的仿真结果得以证实。     

A New Control Technique for Three-Phase Shunt Hybrid Power Filter

This paper presents a nonlinear control technique for a three-phase shunt hybrid power filter (SHPF) to enhance its dynamic response when it is used to compensate for harmonic currents and reactive power. The dynamic model of the SHPF system is first elaborated in the stationary “abc” reference frame and then transformed into the synchronous orthogonal “dq” reference frame. The “dq” frame model is divided into two separate loops, namely, the two current dynamic inner loops and the dc-voltage dynamic outer loop. Proportional–integral (PI) controllers are utilized to control the SHPF input currents and dc-bus voltage. The currents track closely their references so that the SHPF behaves as a quasi-ideal current source connected in parallel with the load. It provides the reactive power and harmonic currents required by the nonlinear load, thereby achieving sinusoidal supply currents in phase with supply voltages under dynamic and steady-state conditions. The SHPF consists of a small-rating voltage-source inverter (VSI) in series with a fifth-harmonic tuned $LC$ passive filter. The rating of the VSI in the SHPF system is much smaller than that in the conventional shunt active power filter because the passive filter takes care of the major burden of compensation. The effectiveness of the control technique is demonstrated through simulation and experimentation under steady-state and dynamic operating conditions.      

LCL滤波器在并联型有源电力滤波器中的设计

在满足相同的高频滤波效果的情况下,LCL滤波器所需的总电感值比L滤波器小,因此更适于在大功率、开关频率较低的电流源控制型并网设备上应用。然而针对该类型滤波器的参数设计不仅关系到开关频率处纹波抑制效果,同时也会影响电流控制器的性能。随着高频谐波抑制效果明显的LCL滤波器在并联型有源滤波器中应用,基于谐波电流跟踪控制器的LCL参数设计需要进一步研究,因此文中基于并联型有源电力滤波器给出一套LCL滤波器设计方法,并通过仿真验证该LCL滤波器的有源电力滤波器的有效性。     

大容量并联型有源电力滤波器的软启动技术

分析大容量并联型有源电力滤波器的系统模型和工作特点的基础上,提出了大容量并联型有源电力滤波器软启动的方法。电流环软启动通过输出电流指令递增实现,电压环软启动则比较了直流侧电压指令逐步升高法、恒定电流充电法、变PI参数调节法三种策略。实验结果表明并联型有源电力滤波器投入电网时直流侧电压上升平稳无超调,输出电流也无冲击现象,证明此软启动方法是有效的。     

An Implementation of an Adaptive Control Algorithm for a Three-Phase Shunt Active Filter

This paper deals with the hardware implementation of a shunt active filter (SAF) for compensation of reactive power, unbalanced loading, and harmonic currents. SAF is controlled using an adaptive-linear-element (Adaline)-based current estimator to maintain sinusoidal and unity-power-factor source currents. Three-phase load currents are sensed, and using least mean square (LMS) algorithm-based Adaline, online calculation of weights is performed and these weights are multiplied by the unit vector templates, which give the fundamental-frequency real component of load currents. The dc bus voltage of voltage source converter (VSC) working as a SAF is maintained at constant value using a proportional–integral controller. The switching of VSC is performed using hysteresis-based pulsewidth-modulation indirect-current-control scheme, which controls the source currents to follow the derived reference source currents. The practical implementation of the SAF is realized using dSPACE DS1104 R&D controller having TMS320F240 as a slave DSP. The MATLAB-based simulation results and implementation results are presented to demonstrate the effectiveness of the SAF with Adaline-based control for load compensation.      

Novel Direct Current-Space-Vector Controlfor Shunt Active Power Filters Basedon the Three-Level Inverter

The growing number of electric drives with non-sinusoidal line currents has given increased interest in active power filters (APF), to avoid grid problems caused by harmonic distortions. In this paper, a novel direct current-space-vector control scheme (DCSVC) is presented for a three-level, neutral-point-clamped voltage source inverter, which is employed as an active power filter. The proposed method generates the compensation current reference indirectly generating an equivalent ohmic conductance for the fundamental component by means of the APF's dc-link voltage control. Based on the fast Fourier transform the compensation of the reactive fundamental current and selectable harmonics can be cancelled, confining the operation to only harmonic compensation and thus saving the APF's apparent power. The novel DCSVC, operating in synchronously rotating coordinates is implemented in a field programmable gate array, realizing the switching states from switching tables. The proposed control reduces the average switching frequency and thus, the switching power loss significantly, compared with a previous DCSVC, operating in stationary coordinates. Simulation and experimental results validate the feasibility and highly dynamic performance of the proposed control, both for harmonic and total non-active current compensation.      

基于RLS自适应滤波器的并联型有源电力滤波器

将RLS自适应滤波器用于有源滤波器直流端电容电压的控制，并将直流端电容电压的控制完全摒弃了传统的PI积分控制，解决了控制参数难于调节且对电路中其他参数的变化非常敏感的问题。而且经过自适应滤波器的直流端电容电压几乎没有任何纹波，不但在电源电压为理想情况时可以起到较好的补偿作用，而且当电源电压发生畸变时也有较好的补偿性能。仿真研究证明了所提出的控制方法的正确性。     

并联有源电力滤波器的启动建压与稳压控制

对直流侧电压控制模型,在基于电流正交分解的基础上进行了简化修正,同时考虑检测延迟环节的影响,基于此模型设计了直流侧电压环的PI调节器。文中还设计了一种限流电阻加在线改变电压放大倍数K值的直流侧启动充电方法。最后,采用基于空间电压矢量电流跟踪法的并联型有源滤波器（SAPF）模型进行上述分析的仿真,仿真结果证明该方法可行。     

并联混合有源电力滤波器的参数设计及仿真

并联混合有源电力滤波器作为一种复杂的电力电子设备,其各个组成部分的参数选取、逆变器的控制策略和系统参数的变化均对滤波性能有一定的影响。文章在分析了这些影响和系统工作原理的基础上,提出一些合适的参数选择方法和控制策略,并用SIMULINK搭建系统模型进行动态仿真验证。     

并联型有源滤波器直流侧电压稳定控制策略

有源滤波器直流侧电压的波动对有源滤波器的稳定运行有很大的影响,针对这个问题,分析了直流侧电压波动产生的原因及对有源滤波器运行的影响,对传统的PI控制提出了基于电压偏差平方的PI控制改进的方法,这种控制直流侧电压的方法对处理传统PI控制的非线性问题也有很大的改进。并通过matlab仿真验证了改进的PI调节控制策略对谐波的消除有很好的效果,这种控制策略通过软件即可实现,不需要增加硬件设备,是一种经济的解决措施。