基于改进小波变换的电力谐波检测方法研究

Power Harmonic Detection Method Research Basedon Improved Wavelet Transform

在电力系统供电优化中,谐波检测是治理谐波的前提,可提高电能质量。目前主要的谐波检测方法中,瞬时无功功率法存在精度低,傅里叶(Fourier)变换法存在频率泄露和栅栏现象,小波包分析法存在运算量大、速度慢、实时性差等问题。提出了一种改进的小波变换的谐波检测方法,结合了小波变换和小波包两种方法的优势。针对特定的谐波频段进行检测,利用小波函数的时频特性,快速有效地提取出特定频率段的谐波分量,标定谐波发生的起止时刻,同时减少谐波检测的计算量,确保谐波准确实时检测。MATLAB仿真结果表明该方法能有效的检测出各个谐波分量,提高检测速度。验证了改进小波变换电力谐波检测方法的实时性。

In the power system, as the premise of harmonic suppression, harmonic detection is necessary to improve power quality. According to problems of the main harmonic detection methods, such as low accuracy of instantaneous reactive power theory, spectrum leakage, fences phenomenon existed in Fourier transform, and complicated computation, slow analysis speed, poor real-time performance of wavelet packet theory, we presented an improved wavelet transform harmonic detection method combined wavelet transform and wavelet packet. Only for a specific frequency band harmonic detection, the time-frequency characteristics of wavelet and wavelet packet were used to extract the frequency of component and calibrate the start and stop times of the specific harmonic frequency. The amount of computation has been reduced and the real-time performance of harmonic detection has been improved with this method. The Matlab simulation results show that the proposed method detects the harmonic components effectively and improves the detection speed. The timeliness of power harmonic detection based on the improved wavelet transform has been verified.