强谐波环境下的无功功率补偿技术

非线性功率用电设备产生谐波电流,导致电磁干扰、功率因数降低,由电容器、串联电抗器组成的谐波滤波装置具有谐波滤除和无功补偿两大功能。工作时不会像传统电容器组补偿那样,在提高功率因数的同时对高次谐波进行放大,而是对谐波进行吸收,提高电源质量。在电抗性补偿系统里,根据需要被补偿的功率计算得出电容,串联谐振电路的串联谐振频率由...     

基于双判据融合的串联变压器磁饱和抑制系统

串联变压器磁饱和抑制系统在抑制过程中会出现电流畸变,无法取得较好的抑制效果。为此,基于双判据融合设计了一种新的串联变压器磁饱和抑制系统,通过串联变压器、保护工作器件和电流互感器设置系统硬件结构。采用二次电流波形斜度模块,检测串联变压器的磁饱和电流,计算二次电流谐波确定谐波基波数值,检测电流和电压波形状态,实现磁饱和抑制。实验结果表明,基于双判据融合的串联变压器磁饱和抑制系统能够有效解决电流畸变问题,抑制后二次测量电流波形和电压波形波动较为稳定,该文方法具有良好的抑制效果。     

一种改进型i_p-i_q谐波电流检测方法的研究

分析了以瞬时无功功率理论为基础的传统的ip-iq谐波电流检测方法,提出了一种改进型ip-iq谐波电流检测方法。该方法预设变换矩阵的频率代替锁相环(PLL),采用Chebyshev型陷波滤波器和Bessel型滤波器串联来构成低通滤波器部分。与传统的ip-iq谐波电流检测方法相比,该方法不仅能够保证较高的检测精度,而且电路结构更为简单,响应速度更快。理论分析及MATLAB仿真结果均验证了该改进设计的正确性和有效性。     

基于多重化技术的低谐波电力电子电路研究

文中分析了多重化技术在整流电路,逆变电路,以及PWM电路中的原理及应用。采用串联多重化的方法设计了移相100串联6重联结电路来消除低次谐波,结果表明了移相100串联6重联结电路可以消除36k±1次以外的谐波,并且使最低次数提高,幅值减小,总体谐波含量减少,且具有减少对电网谐波污染的优点。最后,给出了仿真和系统实验波形。     

10吨6000kW晶闸管串联谐振中频电源整流电路的设计

感应电炉的核心在于中频电源,本文对6000k W串联谐振逆变电源系统整流电路进行了设计。设计了串联谐振式中频电源的主电路结构,采用双路12脉整流电路整流电路,相当于等效24脉整流电路,一方面能减少谐波含量,降低谐波畸变率;另一方面有利于逆变电路晶闸管的均流,实现了对逆变晶闸管的电路均流。     

电容器装置中串联电抗器的作用及其选择

介绍了高次谐波对电容器组的危害,提出用加装串联电抗器的方法可以防止发生涌流和谐波放大现象。建立了并联电容器装置模型,通过电路分析方法推导出电抗率K的计算公式。又通过天津某110kV变电所工程实例,进一步计算验证并联电抗器的电抗率的选择。最后得出结论:对于还没有投运电容器组的电抗器装置,应串联电容器装置并充分考虑电容器组接入母线处的谐波背景;对于已经投运电容器的电抗器装置,其串联电抗器选择是否合理需进一步验算,并组织现场实测,了解电网谐波背景的变化。     

煤矿电网谐波检测方法与治理方案

针对煤矿电网中高次谐波状况,设计出一种基于希尔伯特黄变换电网谐波检测的方法与治理方案。以煤矿6kV电网为例,用MATLAB软件建立串联联结的6脉冲整流电路模型模拟谐波,由控制芯片TMS320F2812完成电压电流信号采集,并根据希尔伯特边际谱得到各次谐波含量,将该谐波含量与换算国家标准对比,根据对比结果建立混合型有源滤波器模型模拟滤波,结果表明了该系统的有效性和可行性。     

矿井提升机串联H桥多电平高压变频器整流电路研究

串联H桥多电平变频器由于其输入输出波形好,谐波小,模块化设计等优点逐渐成为高压变频调速的主流方案。本文针对提升机运行特点,对当前已有的串联H桥多电平高压变频器用整流器进行了对比分析。     

一种基于瞬时无功功率的改进谐波电流检测算法

为满足有源电力滤波器谐波电流检测的高精度、高实时性的要求,文章给出一种对瞬时无功功率的改进方法。这种方法减少了计算量,使得实时性、可实现性增强,可以直接应用于三相三线制,三相四线制以及单相系统的谐波和基波无功电流的检测。并综合考虑FIR滤波器和IIR滤波器的优缺点,使用均值滤波器和Butterworth滤波器的串联滤波方法。计算机仿真表明该改进方法具有检测精度高,响应速度快,易于实现的特点。     

单相谐波检测算法改进研究

谐波一直以来都是电力系统发展过程中影响电能质量和安全稳定运行的一个不容忽视的问题。该文就谐波检测的重要性谐波的危害、有源滤波器以及谐波检测算法的基本原理做了简要的分析介绍,并对单相谐波检测的算法改进进行探讨研究,最后对谐波检测的发展趋势做简要分析介绍。     

一种压电陶瓷执行器动态驱动电源

针对压电陶瓷执行器呈现强容性负载的特性,该文研究了基于误差放大原理的压电陶瓷执行器动态驱动电源,提出采用高压运算放大器结合准互补对称功率放大电路构成的输出级以提高驱动电源的输出电压范围的方法和采用多组准互补对称功率放大电路构成的输出级并联以提高输出峰值功率的方法。通过对实际电路的测试表明,采用上述方法开发的压电陶瓷执行器动态驱动电源不仅输出功率达270 W,且具有良好的静态性能。     

A Novel Three-Phase Hybrid Active Power Filter With a Series Resonance Circuit Tuned at the Fundamental Frequency

In this paper, a novel three-phase hybrid active power filter (HAPF) with a series resonance circuit tuned at the fundamental frequency is proposed for simultaneously suppressing harmonic currents and compensating high-capacity reactive power in high- or medium-voltage power systems. To reduce its rated capacity, the active power filter is shunted to the series resonance circuit by a matching transformer and, thus, greatly reduces its current requirements as well as voltage ratings of semiconductor switching devices. The passive power filters are used to compensate the reactive power with a constant capacity. The validity and effectiveness of this novel HAPF system have been verified by simulation and industrial application results.      

UPQC检测控制方法研究

介绍了一种综合型的电能质量补偿装置UPQC的功能和结构,分析了它的检测控制策略.并在此基础上,提出利用瞬时无功功率理论中的同步坐标变换来提取电网电压基波正序相位的检测方法,它简单易行,实时性好,避免了大量对三的相量计算,且无须相不对称且畸变电压进行锁相和滤波.并介绍了根据UPQC内部功率平衡来实现的串连和并联有源滤波器的综合控制方法.仿真结果验证了上述检测控制方法的正确性.     

AC-DC converter with parametric reactive power compensation

Resonant converters of 50 (60) Hz AC-DC are described, where each half cycle of network voltage the capacitor and inductor of an oscillatory circuit are switched from series into parallel and vice versa. The duration of series and parallel connection and also the transformer ratio are parametrically dependent on load. In the case of short circuit, only the parallel oscillating circuit operates. This restricts sharply the output current. The reactive power of the capacitor and the inductor compensate each other, both in the cases of series and parallel connection. Therefore, the power factor is very high from no load to short circuit. This converter fits very well for supplying arc furnaces, and there is no need for the costly and fast reactive power compensator and filter circuits. The operating principle of the converter, design principles, and a real operating converter rated 5.4 MW supplying a steel-melting arc furnace are described     

An optimization technique for real and reactive power allocation

An economic schedule for real power generation is obtained by a Lagrangian method and the allocation of reactive power generation is determined by a gradient method. Alternate real and reactive power requirements for economic system operation are computed until the total cost is minimized within the limitations imposed by system constraints. Repeated solutions of the network equations are used to incorporate the effects of transmission losses in lieu of a precalculated transmission loss formula. The computer program provides a means to determine the optimum use of available real and reactive power generation and to plan economically for future requirements.     

功率因数对工厂供配电系统电能质量的影响

介绍了功率因数对工厂供配电系统电能质量的影响,为了提高电能的利用率,在此研究了如何减少感性负荷的无功储能。详细介绍了2种提高功率因数的方法：传统法和补偿法。传统法是对感性负荷自身进行改造或运行状态的改变来减少无功损耗;补偿法是通过给感性负荷并联电容器纽进行无功补偿的一种新型方法。目的是为了提高电能的利用率和减少有色金属的浪费。研究结果证明,通过这2种方法,系统的功率因数可以提高的1倍以上,对节约电能有很大的帮助。     

A Modular Strategy for Control and Voltage Balancing of Cascaded H-Bridge Rectifiers

In this paper, a new strategy for voltage balancing of distinct dc buses in cascaded H-bridge rectifiers is presented. This method ensures that the dc bus capacitor voltages converge to the reference value, even when the loads attached to them are extracting different amounts of power. The proposed method can be used for an arbitrary number of series H-bridges, different voltage levels, and different power levels in unidirectional or bidirectional rectifiers. To reduce the current harmonics and distortion, the input current is programmed to be sinusoidal and in phase with the input voltage; however, it is possible to adjust the input power factor to control both the active and reactive powers. In the proposed approach, both the low frequency (stepped modulation) and high frequency [pulse-width modulation (PWM)] switching methods are utilized to improve the performance of the rectifier. Using theoretical analysis, the acceptable load power limits for a rectifier with N-H-bridge cells are derived. The validity of the proposed method is verified by simulation and experimental results.      

谐波和无功电流补偿的分析与实验

在供电电网中，由电力电子设备产生的谐波和无功电流已经成为主要的污染源。文章提出一种补偿谐波和无功电流的精巧设计，采用电力有源滤波器实时地向电网注入补偿电流。该方法补偿有效，无附加条件且应用方便。     

AC-DC Converter Minimizing Induced Harmonics in Industrial Power Systems

Conventional ac-dc converters present two important disadvantages: they create harmonic currents and require reactive power. To reduce these drawbacks, a diode rectifier is directly connected in series with a chopper controlled by pulsewidth modulation. Both are preceded by a series inductance (added to the equivalent one of the power system) and a shunt capacitor. This study is applied to single-phase powerful electric locomotives. Equivalent three-phase systems are not so interesting.