小波(包)电能质量分析的综合性能评估

Comprehensive estimation of power quality based on wavelet (packet) transform

分析了Daubechies系小波随阶数增大,时频域分析特性的递变规律;归纳了用于电能质量综合性能分析与评估的小波选取原则;比较了Daubechies系小波对五种典型电能质量问题的分析结果。仿真结果表明,Daub20小波变换能够兼顾电力系统暂态和稳态电能质量问题的分析要求,同时准确地完成暂态扰动发生时刻定位、扰动时间内信号特征提取以及谐波检测等工作。在电力系统多重扰动存在的情况下,能够有效地对暂态和稳态电能质量问题进行分析,有利于快速、实时地进行电能质量综合性能评估。

Analyzed the performance changing rules of Daubechies wavelets in both timedomain and frequency-domain, when the wavelet order number N gradually changed. Summarized the principle of selecting wavelets which were used in the comprehensive estimation of power quality. Established five typical mathematical models for disturbances of the power network. Compared the results of analysis based on Daubechies wavelets. The results of simulations showed that the Daubechies 20 wavelet transform could satisfy the requirements of both the steady-stationary disturbance and transient power quality analysis. It could not only accurately identify the moment when the disturbances happened but also measure harmonics precisely. For the multi-disturbance in power system, it could comprehensively estimate the power quality correctly, effectively and rapidly.