单相PWM整流器的特定谐波改善控制方法

针对大功率应用场合的单相PWM整流器,为了实现其网侧电流正弦化、减少网侧电流3次谐波含量和提高输入端功率因数,探讨了一种适用于单相PWM整流器的网侧电流3次谐波抑制方法。首先分析了单相PWM整流器的工作原理和网侧电流的3次谐波产生原因,并将该新型谐波抑制方法与常规控制算法进行了对比。计算和仿真实验表明该新型控制算法能够有效抑制网侧电流的3次谐波,并降低总谐波畸变率。     

新型谐波抑制变压器

以往谐波抑制思想主要采用谐波电流对消或谐波电流旁路等方式进行滤波的电抑制方式，在这一过程中，谐波耦合变压器仅作为将谐波电流注入电网独立设备，变压器的一般供电功能和谐波滤波功能相对分离，没有从电力系统的整体性能进行设计开发。谐波抑制变压器将常规供电功能和谐波抑制功能集于一体，它的谐波抑制思想是基于谐波磁场抑制方式，即在主变压器磁路中改变谐波磁阻以防止二次侧谐波向一次侧渗透，该变压器适应于投入运行在区域用户、大型电力装置等与输电网之间的接口位置，用以减少负载谐波源对电网或它们之间的危害。谐波磁抑制技…     

基于谐波观测器的永磁同步电机谐波电流抑制策略研究

针对传统基于谐波注入的抑制策略只对特定的次电流谐波有效,而对其他幅值较高的低次谐波抑制效果不够理想的问题,在推导出与永磁同步电机(permanent magnet synchronous motor,PMSM)、变流器及负载非线性等因素有关的电压、电流谐波解析表达式的基础上,提出一种新颖的基于谐波观测器的电流谐波抑制策略,通过对电压谐波的控制实现对PMSM/变流器系统中全频次低频电流谐波的有效抑制。所设计的谐波电流调节器通过与电流内环的基波电流调节器的并联,实现了对电流的基波分量和谐波分量的解耦控制,在不影响基波电流控制目标的前提下,实现了对于低频各次电流谐波的有效的抑制。为验证算法的有效性,在实验室搭建PMSM/变流器系统测试平台,进行电流谐波抑制策略的实验验证工作。动静态实验结果表明,该方法运算量小、实现方式简单,对各次低频电流谐波均有较为明显的抑制效果,可以有效的改善电流波形。     

基于电压注入的高速永磁电机谐波电流抑制方法

针对高速永磁同步电机在运行过程中相电流谐波含量高这一问题,提出了一种基于电压注入的高速永磁同步电机谐波抑制方法。在考虑存在谐波电流的前提下建立了高速永磁电机数学模型,采用闭环谐波电流检测方法,提取5次和7次谐波电流,根据电机谐波数学模型计算谐波电压补偿量,在传统的双闭环系统上设计增加了谐波电流反馈环和谐波电压补偿环,通过注入谐波电压的方式来抑制高速永磁电机运行时相电流中的谐波分量。仿真和实验结果表明,基于电压注入的高速永磁同步电机谐波电流抑制方法可以有效抑制电机相电流中的谐波,验证了该方法的有效性。该方法易于实现,适应性强。     

技术问答

问:抑制、减小用户设备谐波危害的技术措施有那些? 答:抑制、减小谐波危害主要从注入电网的谐波电流源入手解决。一是对谐波源采取措施,减少产生的谐波含量;二是在谐波源处安装滤波器,就近吸收谐波源产生的谐波电流。具体实施的技术措施不外乎从三个方面加以解决。1 增加电力系统的容量、改善电网结构a.改善电网结构。电网结构的改善,能增加非线性负荷接入点母线的短路容量,以减少     

基于谐波抑制的共母线开绕组永磁同步电机减振控制

为了减少共母线开绕组永磁同步电机(OW-PMSM)驱动系统中的电流谐波,抑制由径向电磁力引发的电机振动,提出了一种基于零序电流闭环的零矢量重分配随机开关频率空间矢量脉宽调制(SVPWM)算法。该算法通过选取的零矢量产生共模电压,抵消由非零电压矢量带来的共模电压,将零序电流闭环后动态抑制零序电流,有效地减少了相电流3次谐波含量。同时,针对调制策略固有的相电流高频谐波分量,通过SVPWM中开关频率随机化,使得开关频率及其整数倍处高频谐波幅值大大减少。试验结果表明,该方法能有效降低高低频段电流谐波幅值,实现OW-PMSM全频段的减振控制。     

直流偏置型正弦电流电机谐波抑制策略

为了抑制直流偏置型正弦电流电机中的谐波电流,同时保证电机的动态性能,研究了一种谐波电流抑制技术。在多旋转坐标系中对各次谐波电流进行闭环电流调节,使得这些谐波电流可以在稳态和动态过程中被有效地抑制,该控制策略不受电机饱和效应的影响。通过台架实验验证了该策略的有效性。     

串级调速系统的谐波和抑制

本文对静止式串级调速系统中的电流谐波及其特点作了详细分析,並阐明了强迫换流串级调速系统线电流严重畸变的原因。为了减少和抑制这些谐波,给出了三种可行的解决方案,以求在改善和提高串级调速系统的功率因数的同时,谐波亦得到抑制。除了进行理论分析外,亦由串级调速系统的实测的频谱图和电流波形给予证实。     

基于LMS自适应滤波器的PMSM谐波抑制方法

为有效抑制电流谐波，在原有的PI控制器基础上，基于最小均方自适应滤波器(LMS-ANF)改造控制器结构，使得永磁同步电机特定次电流谐波得到抑制。通过在传统d,q坐标系矢量控制算法的基础上增加自适应滤波器模块，将采样得到的实际电流作为输入，提取、放大实际电流中的特定次谐波电流，通过PI调节器对谐波误差放大后的电流进行调节，得到控制电压，取得了良好的谐波抑制效果。通过仿真以及台架实验，证明了该控制策略对于抑制电流谐波的有效性。     

抑制大功率整流电路谐波的三次谐波电流注入法

为消除和减少大功率整流电路中高次谐波对电力系统的危害，必须对此类整流电路所产生的谐波加以抑制和削弱。文中介绍了三次谐波电流注入法的起源、发展及基本原理。该方法是抑制三组二极管桥式整流器中谐波的新方法。文中还分析了输入电流的特性，最后对该方法的发展进行了展望。     

谐波对电力设备的影响

在电力系统中,谐波源产生的谐波对电网本身的安全可靠运行造成严重威胁。介绍了谐波原理;给出了公用电网谐波电压（相电压）限值和注入公共连接点的谐波电流允许值;分析了公用电网中谐波电流和谐波电压对用电设备和电网本身的危害;阐述了抑制和治理谐波的几种方法。     

Power systems and harmonic factors

Harmonic currents and distortions in power systems are a natural progression in society's use of electrical equipment. A proliferation of harmonics can cause problems-some severe. However, the benefits we receive from electrification far outweighs the downside to this problem. There is an increased awareness among equipment designers, manufacturers, and users for the need to reduce power system harmonics. However, much work still needs to be done. This paper describes how harmonics arise from nonlinear loads and their effects on the power system. The problems that arise from harmonic current flow are straightforward and simple. The two main problems are abnormal heating of components and disruption of operation. The paper also describe mitigation of harmonic effects which take on two strategies: one is to reduce the harmonic effect; the other is to reduce or control the harmonic content     

10kV以下供电系统电源谐波的防治

10kV以下供电线路所带负荷通常是多种负荷的叠加,即非线性负荷,是供电系统谐波产生的主要原因。分析了输入谐波电流对供电系统的影响、输入电压波形畸变的危害;结合现行规范对谐波限制的要求,指出了降低配电系统谐波的主要措施和治理原则。对于提高供电系统的电能质量,运行安全,有着十分重要的现实意义。     

三相有源电力滤波器控制方法的研究

基于单周控制的三相有源电力滤波器(APF)虽不需谐波检测电路,电路相对简单,但只能同时补偿谐波和无功电流,且要求电源电压无畸变,故有局限性。为此将ip-iq谐波检测法和单周控制方法相结合,利用ip-iq法检测负载电流的谐波和无功分量,以单周控制作为电流跟踪控制方式,推出单周控制方程,基于此的建模和仿真研究结果表明:APF可灵活地补偿非线性负载的谐波和无功电流,且补偿效果良好,有一定可行性。     

Designing harmonic filters for adjustable-speed drives to complywith IEEE-519 harmonic limits

This paper discusses the application of the revised IEEE 519 harmonics standard to typical industrial facilities employing adjustable-speed drives (ASDs). The harmonic generation characteristics of ASDs are described. Requirements for control of the harmonic currents are developed as a function of the ASD characteristics, overall plant loading level, power system characteristics, and power-factor-correction requirements. Filter design procedures are presented for controlling the harmonic currents injected into the power system     

Developing a harmonics education facility in a power systemsimulator for power engineering education

This paper describes a newly installed harmonics education facility in detail to teach students about harmonics related problems in a power system. A nonlinear load, which produces harmonic currents, and a harmonic filter, which is a mitigation facility, are merged into an existing power system simulator for advanced power engineering education. The nonlinear load is a widely used three-phase, 6-pulse controlled rectifier. The filter bank is designed to eliminate the characteristic harmonic currents. This paper also shows the resonant condition caused by shunt capacitors which are usually used for power factor correction. Several suggested experiments are given to teach students about harmonics related problems including harmonic sources, measurement, resonance, limitation, and mitigation. The harmonics education facility greatly extends and promotes the performance of the power system simulator     

Harmonic measurements, analysis, and power factor correction in amodern steel manufacturing facility

Maximizing electric power transfer directly affects the productivity of an electric arc furnace operation. Arc furnaces and rolling mill loads operate at power factors that result in penalty charges and lower bus voltages. In addition, the nonlinear characteristics of the furnace arcs and rolling mill drives generate significant harmonic currents that flow through the plant and utility power system. These harmonic currents cause system voltage distortion and power loss in the system, and can interact with power factor correction capacitor banks leading to equipment failures. This paper presents the analytical technique used to correct power factor in a modern steel manufacturing facility. The study included field measurements, harmonic analysis, and filter design work to reduce the amount of harmonic distortion in the plant. The modeling of arc furnaces and rolling mills for a harmonic analysis study is also discussed. The solutions recommended in this paper to increase power factor and reduce harmonics can be applied to other steel manufacturing facilities to improve power quality and therefore plant productivity     

Application Considerations in Handling Effects of SCR Generated Harmonics in Cement Plants

Loads that inject harmonics into power distribution systems have existed for many years. Such harmonics produced by discontinuous conducting devices and nonlinear loads created few recognized problems for most cement plant power distribution systems installed prior to 1960 because of the small amount of harmonic generating loads present on such systems. With the advent of large thyristor-controlled equipment, considerable attention has been directed to harmonic currents required by such loads and the resultant harmonic voltages produced by the passage of such currents through the power system.     

三相四线制系统谐波检测p-q-0法的研究

以瞬时无功功率理论为基础,介绍了针对三线四线制系统谐波电流检测和无功补偿所提出的p-q-0法,分析了瞬时无功功率理论在三线四线制电力系统下的物理意义,并给出了该系统下谐波和无功电流的检测控制算法原理图,详细讨论了三相负载不平衡时的补偿效果。通过理论分析,在M atlab环境下对三相不平衡负载电路仿真证明,当电网电流发生严重畸变时,p-q-0法不仅能准确、实时地消除三相四线制系统中的谐波电流,对中线电流抑制及无功功率补偿也有较好的效果,并且补偿后的电源瞬时三相功率为定值。     

定频积分控制的三相4线有源电力滤波器

有源电力滤波器(APF)是谐波抑制和无功补偿的有效方法.采用定频积分控制的有源电力滤波器摆脱了先检测谐波和无功电流,然后根据检测信号产生补偿电流的传统控制方法,简化了有源电力滤波器的结构.将该方法用于三相4线制有源电力滤波器,抑制谐波,提高功率因数并解决三相不平衡问题.