基于RITHAF的电网谐波分析与治理系统装置的研制

针对某变电站在谐波治理的同时需要进行无功补偿的要求,研制了一种基于新型谐振阻抗型混合有源滤波器(Resonant Impedance Type Hybrid Active Filter,RITHAF)的谐波分析与治理装置.在该装置中引入基波串联谐振电路使得RITHAF的无源滤波器在补偿无功时不会增大有源部分的容量,弥补了现有混合有源滤波器不能同时满足这两方面要求的缺陷.文中详细介绍了该装置的滤波原理及谐波分析、控制和主电路三个子系统中的关键技术.该装置已在某220kV变电站中挂网运行,效果良好.     

利用傅氏算法求取正确的基波及谐波分量初始角方法的研究

在采用微机实现的故障保护、远距离测量等场合,从测量信号中提取正确的有用信号至关重要,而提取正确有用信号的前提条件是优秀的测量方法、手段及正确的算法 傅氏算法是一种简单而有效的算法,它能有效地消除高次谐波,算法稳定性好、精度高。但如果直接利用基本的傅氏算法公式从信号中提取基波及谐波分量,则有时所求得的基波或谐波分量的相角并不正确。本文对如何利用傅氏算法来求取正确的基波或某次谐波初相角方法分二种情况进行了研究,分析了原因,提出了改进办法,仿真试验证明效果良好。     

电力系统中谐波的影响及检测方法

本文着重论述了电力系统中谐波的危害及其对电能计量的影响,讨论了电力谐波的检测方法,并提出了一种基于DSP的电网谐波分析仪的设计方案。     

三相谐波检测的DSP实现方案

针对有源滤波器的谐波检测算法进行研究,采用了实时性较高的基于瞬时无功功率的ip - iq法来进行谐波检测,分析了算法及二阶Butterworth低通滤波器的数字化设计,并以TMS320F2812型DSP为核心,搭建试验平台,具体分析了实验的软、硬件设计,给出部分硬件电路图,画出了软件流程图,完成谐波检测实验,并取得良好...     

Hybrid demodulation concept and harmonic analysis for single/multiple power quality events detection and classification

A novel real-time analysis of power quality (PQ) events has been presented using amplitude and frequency demodulation concepts. The earlier techniques were analyzing the few cycles of the power signal based upon wavelets, having the computational complexity of the order O(n²). In the proposed method, PQ events can be considered as similar to various modulating signal forms. In this paper, the concept of demodulation has been used to separate various single/multiple event patterns and MUSIC harmonics algorithm has been used to detect the presence of the various harmonics. These techniques have been well tested on transient, sag, swell harmonics and their combinations in real-time. Fuzzy classifiers have been used for the classification of PQ events from the knowledge base, obtained from amplitude demodulation, frequency demodulation and MUSIC harmonic algorithm. It is concluded from the confusion tables that the efficiency of single/multiple PQ events recognition of fuzzy product aggregation reasoning rule (FPARR) classifier is higher.     

Diode-clamped multi-level power converter with a zero-sequence current loop for three-phase three-wire hybrid power filter

This paper proposes a three-phase three-wire hybrid power filter configured by a three-phase passive power filter and a three-phase diode-clamped multi-level power converter with a small power capacity of zero-sequence current loop connected in series to compensate for the harmonic currents of nonlinear load. The salient feature is that a small power capacity of zero-sequence current loop is applied to overcome the problem of balancing voltages of two DC capacitors for a diode-clamped multi-level power converter applying in the three-phase three-wire hybrid power filter. A laboratory prototype is developed to verify the performance of the proposed three-phase three-wire hybrid power filter. The experimental results have demonstrated the feasibility and practicality of the proposed three-phase three-wire hybrid power filter.     

Triplen harmonics: Myths and reality

In a symmetrical and balanced three-phase system with distorted waveforms, a well-known rule states that each harmonic order corresponds to a specified sequence (positive, negative or zero). In this ideal case, the current in the neutral conductor (or more generally in the return path) contains only triplen harmonics. However, this rule is no longer valid in practical distribution systems subject to unbalance and waveform distortion, in which phase and neutral currents at any sequence generally contain components of any harmonic order. Possible improper extension of the ideal case concepts to general situations may create a sort of myth, to be removed by providing tutorial and practical examples.This paper provides a direct quantification of the extent to which non-triplen harmonics are present in the zero-sequence current components and triplen harmonics are present in the positive and negative sequence current components. An original set of indicators, built on the basis of the theoretical symmetrical component-based framework developed by the authors, is introduced for assessing the specific impact of the triplen harmonics at the different sequences. Some classical myths based on the ideal case are illustrated and discussed on specific examples including theoretical cases and experimental analyses, quantifying the actual role played by the triplen harmonics in these applications.     

谐波传动中齿轮相对转角的正确解

目前关于谐波齿轮传动啮合参数及几何参数的选择主要来源于所列参考文献, 本文指出上述文献中关于谐波传动齿轮相对转角的计算公式是不准确的; 作为验证, 本文用直接法推导出正确结论; 最后讨论了由上述不正确公式所引起的齿轮啮合侧隙的误差及其计算公式。     

振动台有限元动力学分析

为了得到某成型模振动台在未知频率下的生产应用最佳振幅,利用有限元方法对其进行模态和谐响应分析,得到振动台的前十二阶振型与确定了振动台随正载荷激励下的稳定响应。对计算结果进行分析得到了在一个频率的左右小范围内的到了振动台的最佳振幅,某为类似振动台设计与改进提供了理论依据。     

单相Pwm整流器瞬时电流控制的研究

介绍了单相PWM整流器的工作原理,并在此基础上推导出单相PWM整流器的数学模型。然后通过此数学模型搭建了仿真框架,最后用MA丁LAB/Simulink进行了仿真研究,结果表明瞬时直接电流控制使得单相PWM整流器具备很好的稳态和瞬态性能,实现交流侧功率因数接近于1。