Suppression of parallel resonance and mitigation of harmonic distortion through shunt active power compensation

In this contribution a solution to the parallel resonance problem that can be present in practical applications of shunt Active Power Filter (APF) compensation is proposed. The proposed solution involves turning the shunt APF scheme of compensation into a Shunt Hybrid Filter (SHF) configuration. A Linear Quadratic Regulator (LQR)-based switching controller was specifically designed for this hybrid scheme of compensation, maintaining stringent performance requirements on the tracking of filtering currents and the draining of the harmonic ripple currents. Results obtained with Matlab/Simulink® illustrate an effective and sound system of compensation which also reduces the necessary KVA rating of the APF.     

电网谐波功率潮流方向与电力滤波器的应用

分析了电网谐波功率潮流方向对其安装的无源滤波器和有源滤波器的影响,证明了只有根据电网谐波功率潮流的方向和谐波源类型来确定所使用的滤波器及其工作方式才能达到预期的滤波效果。     

Analysis of cascaded multilevel inverters for active harmonic filtering in distribution networks

This paper aims at the investigation of an active power filter (APF) comprised of a transformerless multilevel inverter (MLI) for power conditioning in three-phase three-wire distribution network. The inverter topologies used here are three, five, seven and nine-level. The system configuration mainly involves cascaded MLI structure of APF, generation of compensation filter currents based on instantaneous active and reactive current component (i_d–i_q) method and dc-link voltage regulation using a PI controller. Not many papers focus on the regulation of dc-link capacitor voltage. Here we have proposed the implementation of bacterial foraging optimization (BFO) to extract the gains of PI controller. The proposed work provides improved dc-link voltage regulation, quick prevail over current harmonics and reduction of overall source current THD. Adequate MATLAB/Simulink simulation results are presented for the different cascaded MLIs discussed above. Additionally, the performance has been validated in real-time using Opal-RT Lab simulator considering three different conditions of supply i.e., balanced sinusoidal, balanced non-sinusoidal and unbalanced sinusoidal.     

针对典型谐波源的有源滤波器及仿真研究

该文用HatlabSimulink建立了带典型负载的电力有源滤波器的仿真模型,应用瞬时无功功率理论,以三相全桥晶闸管全控整流桥为负载,模拟实际系统,用于检验其策略和参数在实际条件下的工作情况。仿真模型的结果表明:基于瞬时无功功率理论的有源滤波器,对于电网中最典型的谐波源--三相桥整流器能达到良好的效果。     

基波磁势自平衡谐波抵消式有源滤波器的优化设计

提出一种基波磁势自平衡谐波抵消式串联有源电力滤波器(SAPF)的无源电力滤波器(PPF)优化设计方法.该滤波器只需要考虑变流器及二次侧所接的电感L和电容C所组成的基渡谐振电路;采用粒子群优化算法(PSO)直接应用于求解连续变量优化问题,对于离散优化或混合整数的优化,仅需对每一代的微粒速度和位置作离散化处理.论述了PPF优化的数学模型、PSO求解PPF支路参数的实现流程.通过对基波磁势自平衡谐波抵消式SAPF的PPF的优化设计结果表明:滤波器投运后系统电流波形畸变率由24.4%下降到3.06%,功率因数由0.7提高到0.96.     

Implementation of the shunt harmonic voltages compensation approach

Instead of injecting harmonic currents to compensate those drawn by distorting loads, in this paper a shunt active filter is used for generating harmonic voltages to compensate harmonic voltages at the point of common coupling; the main advantage in using such a compensation approach is that, when the aim is to reduce or eliminate the harmonic voltages at the point of common coupling only one active filter is required. For determining the harmonic voltages such a filter must generate, two simple and practical methods are proposed in this paper; the effectiveness of these methods was evaluated using a 1-kW prototype of an active filter operating according to the shunt harmonic voltage compensation approach. In addition, the laboratory results were comparable to those obtained with the ATP-EMTP simulation software.     

Indirect current control of active filter for harmonic elimination with novel observer-based noise reduction scheme

Active power filters have been developed recently to solve the harmonics disturbance problems on power system networks. The direct current control scheme is generally used to control the harmonic compensating current directly for current source active power filters. To improve the characteristics of harmonic elimination, the voltage regulation scheme is proposed which regulates the filter capacitor voltage at the input side. Hence the voltage regulation scheme is an indirect current control technique for making sinusoidal line current. To implement this proposed scheme, the electronic differentiator should be used. By using the conventional differentiator, high frequency noise is generated in the controller. This deteriorates both the accuracy and reliability of the controller. To reduce this noise, a novel observer-based noise reduction scheme is proposed for our active filter system. The observer-based algorithm and characteristics of indirect current-controlled active filters are investigated through simulations and experiments.     

Modified static VAR compensator using a large value AC capacitor

To overcome some of the limitations of conventional static VAR compensators (SVCs) which are widely used for reactive power compensation, a modified SVC (MSVC) has been proposed. MSVC uses a large value AC capacitor. The large value AC capacitor is realized using unipolar DC capacitors and power semiconductor devices. Unlike the conventional SVCs, the proposed MSVC does not require additional shunt passive filters for harmonic filtering. MSVC has been verified through analysis and simulation. A practical implementation of MSVC has been realized and tested.     

一种新的混合型有源电力滤波器控制方法

提出一种新的控制策略并应用于混合型有源电力滤波器,实现电力系统无功与谐波的统一补偿。将滤波问题转化为谐波抑制问题,用无静差极点配置控制方式控制无功补偿,用适合于电路拓扑的谐波抑制策略进行谐波补偿,该控制方法具有严格的数学基础,并对各种负荷变化的干扰、参数摄动及未建模动态具有很强的鲁棒性,并能够简化谐波检测。详细阐述了控制方法的原理,仿真结果表明了该方法的有效性及令人满意的性能。     

注入式混合型有源滤波器研究

提供了一种大容量、低成本的注入式混合型有源滤波器以适用于高压系统同时进行谐波抑制和无功补偿,其中,利用大容量无源滤波器实现谐波抑制和无功补偿;采用有源滤波器改善系统滤波效果并阻尼无源滤波器与系统阻抗之间的串、并联谐振。讨论了采用检测电网电流的控制策略时,注入式混合型有源滤波器的工作原理,其基本思想是通过对有源部分进行适当控制来等效增大电网支路的谐波阻抗。从抑制电网阻抗与无源滤波器之间的串、并联谐振,改善无源滤波器的滤波效果以及提高整个系统的鲁棒性3个方面详尽分析了注入式混合型有源滤波器的稳态补偿特性。相关仿真结果及工程应用效果均证明了该混合型有源滤波器对于同时进行谐波抑制和无功补偿的可行性。     

Active power filter for three-phase four-wire electric systems using neural networks

This paper presents the design of neural networks compared with the conventional technique, a hysteresis controller for active power filter for three-phase four-wire electric system. A particular three-layer neural network structure is studied in some detail. Simulation and experimental results of the active power filter with both controllers are also presented to verify the feasibility of such controller. The simulation and experimental result show that both controller techniques can reduce harmonics in three-phase four-wire electric systems drawn by nonlinear loads and can reduce neutral current. The advantage of the neural network controller technique over hysteresis controller technique are less voltage ripple of d.c. bus, and less switching loss. Furthermore, the neural networks controller has better fault tolerance than the hysteresis controller.     

Improved tracking of shunt active power filter by sliding mode control

An improved tracking technique of the reference current waveform in a shunt type active power filter is proposed in this paper using sliding mode control and feedback linearization. Feedback linearization approach helps to reduce the complexity of the controller. Excellent tracking is achieved in both for steady state and dynamic performance. A three-phase four-wire system is considered. The proposed algorithm is simulated first in MATLAB/SIMULINK. An experimental prototype using a dspace1104 based controller is also produced in the laboratory. Results from simulation match well with the corresponding results from experimental prototype confirming the usefulness of the proposed technique.     

供用电系统谐波滤波与无功功率补偿仿真软件

谐波治理的重要手段是采用各种形式的滤波器,开发实用的滤波器设计软件非常必要。介绍了所开发的供用电系统谐波滤波与无功功率补偿仿真软件的基本功能及特点:用工程文件方式保存工程设计基本参数、滤波方案及滤波器参数配置等;可在一个数据表中进行4种滤波器任意组合滤波方案的设置;仿真计算滤波电容器额定参数等,并可在额定频率和频率偏差情况下进行滤波效益与参数校验工作。所开发的软件参数输入与修改便捷,可方便地进行用户谐波电压与电流超标情况、电容器谐波放大问题分析、滤波效果校验、滤波器阻频特性分析等。在某钢厂的应用实例证明该软件可靠、稳定、方便。     

有源电力滤波器任意次谐波电流检测的新算法

有源电力滤波器是一种消除电力系统谐波污染的重要装置，随着电力电子技术的发展，它的使用也越来越广泛。针对有源电力滤波器的特点，基于瞬时无功功率理论，提出一种对于任意指定次数的谐波电流的检测算法。该算法能够克服数字式控制器延迟时间对于谐波补偿的影响，可实现谐波的实时补偿。理论分析和仿真结果证实了所提方法的正确性。     

Active power filters for harmonic cancellation in conventional and advanced aircraft electric power systems

Conventional and advanced civil aircraft electric power systems are simulated and controlled to be within standards regarding the voltage magnitude and frequency everywhere in the system at different loading scenarios. Harmonics in conventional and advanced aircraft power systems are calculated and reduced using a well-designed active power filter. The control circuit of the filter is based on the perfect harmonic cancellation method. The designed filter results in bringing the harmonics in both aircraft systems down to be within the standard limits of IEEE-519 and MIL-STD-704E.     

Fuzzy logic controller for three-level shunt active filter compensating harmonics and reactive power

In this paper, the three-level inverter is used as a shunt active power filter, making use of the multilevel inverter advantages of low harmonic distortion, and reduced switching losses. This PWM inverter is employed as shunt APF compensating reactive power and suppresses harmonics drawn from a nonlinear load. Most previously reported three-phase active power filters are based on two-level inverters with conventional controllers requiring a complex and a complicated mathematical model. In order to overcome this problem a fuzzy logic controller applied and extended to a three level shunt APF is proposed.     

单相并联型混合电力滤波器中谐波检测量的选取

以单相混合型电力滤波器为对象,讨论了有源电力滤波器(APF)中谐波检测量的选取,即APF电压的不同表达式对混合电力滤波器滤波效果的影响。提出了5种APF电压表达式,这5种方式中后2种情况下都能使系统达到理想的滤波特性,一种是同时检测电网电流、负载电流和连接点处的电压;另一种是同时检测负载电流和连接点处的电压。     

并联混合型有源滤波器控制策略研究

提出了一种并联混合有源电力滤波器(APF)的拓扑结构;分析了在不同控制策略下有源滤滤器的滤波原理及其优劣。实践表明,所提出的有源电力滤波器不仅有较好的滤波效果,而且APF逆变器的容量较小,因而工程应用价值较高。     

稳定/脉冲直流电源用并联有源电力滤波器的四种控制方法分析

选择合适的有源电力滤波器控制策略，对实现高性能的有源滤波非常重要。本文对用于高精度、低纹波稳定/脉冲直流电源的并联有源电力滤波器的四种控制方法，包括：检测电源侧与负载侧纹波电流的控制方法、检测电源侧与负载侧纹波电压的控制方法进行了比较研究。结果表明，对于具有大电感的磁铁励磁电源负载，采用检测负载纹波电压的控制方法具有显著优点。该方法是通过检测负载的纹波电压来控制有源电力滤波器的输出，使负载纹波电流分流，从而降低负载电流纹波。在对传感器和电路元件精度要求不高的情况下，该方法很容易实现大功率直流稳定/脉冲电源的低纹波要求。一台实际的运行的工业装置测试表明，其电流纹波达到了 。     

有源电力滤波器并列运行方案

在某些实际工业生产中,为保证供电可靠性会采用经闭合母联断路器连接的2条母线向非线性负载供电的结构。采用无源滤波器治理谐波时,谐波电流会在母联断路器和各支路间流动。针对该运行工况,提出了有源电力滤波器(APF)并列运行的谐波治理方案。详细分析了谐波穿行现象产生的原因以及APF并列运行抑制谐波穿行的原理;通过PSCAD/EMTDC软件仿真对分布式无源滤波方案和APF并列滤波方案的滤波效果进行了比较,对负载扰动、无源滤波支路投退等运行工况进行仿真分析。结果表明:APF并列运行的谐波治理方案能有效解决分布式无源滤波方案中存在的谐波电流吸收率低、谐波电流穿行、滤波支路易过载、电能质量较差等问题,具有较强的实用价值。