小波变换在三相不对称系统谐波检测中的应用  

Harmonic Measurement of Three-phase Asymmetrical System Based on Wavelet Transform

作　　者：周林[1] 夏雪 万蕴杰[3] 张海[1] 雷鹏[1] 

机构地区：[1]重庆大学高电压与电工理论新技术教育部重点实验室,重庆400044 [2]西南电力设计院,成都610021 [3]广东省建筑设计研究院,广州510010

出　　处：《高电压技术》2007年第3期109-112,124,共5页High Voltage Engineering

基　　金：重庆市自然科学基金资助项目(CSTC2005BB2172)。~~

摘　　要：针对小波变换在三相不对称系统的谐波检测中无法分离出系统中的基波负序信号的局限性,提出了一种基于周期交错的小波MALLAT多分辨率分解的测量方法,它根据三相相电流在3/2变换后的正余弦特性,利用1/4个工频周期交错滤除基波信号中的负序成分,再利用小波多分辨率分析提取基波正序信号。在详细介绍了该周期交错算法的原理、流程及计算公式后以TMS320LF2407数字信号处理器为核心建立了验证该算法的实验系统。实验结果表明,该周期交错-小波变换算法可以克服单纯小波频带划分的局限性,有效地检测出三相不对称系统中的基波正序及负序电流分离,从而计算出总的有害电流。Wavelet is a tool of digital signal processing and plays an important part in harmonic measurement of power system. However, because of the effect of the negative sequence of fundamental frequency signal and the limit of the frequency division of wavelet, wavelet transform is restricted in the use of harmonic measurement of three-phase dissymmetrical system. A new approach of harmonic measurement based on Period-interleaving of MALLAT arithmetic for dissymmetrical system is put forward in this paper. According to the characteristics of sine and cosine of three-phase dissymmetrical current after 3/2 transformation and the phase difference between 1/4 period, the negative sequence of fundamental frequency is counteracted by 1/4 period interleaving, then the positive sequence of fundamental frequency can be separated from the signals of high frequency by MALLAT arithmetic. The principle and the formula of this new method is put forward. To prove the new method of harmonic measurement based on MAL- LAT arithmetic, the method is programmed by assembly languages , and an actual three-phase asymmetrical system and a measurement system based on TMS320LF2407 Digital Signal Processor is established. The experimental resuits reveal that the proposed method based on period-interleaving could overcome the limit of wavelet in the use of harmonic measurement of three-phase asymmetrical system and detect the positive sequence of fundamental frequency, then the total harmonics are detected.

关 键 词：谐波检测 小波变换 MALLAT算法 三相不对称系统 周期交错 基波正序信号 

分 类 号：TM935[电气工程—电力电子与电力传动]