采用不完全S变换的电能质量扰动检测方法

Detection Method of Power Quality Disturbances Using Incomplete S-transform

S变换因其优良的时频特性而在电能质量扰动检测和定位方面获得了广泛的应用,但由于S变换计算时采用等间隔采样频率点,因而计算量较大。为解决此问题,基于S变换的电能质量扰动检测方法一般通过提取模时频矩阵的特征量实现而不需要利用S变换模时频矩阵的所有向量,分析了S变换的快速计算过程,并据此提出了不完全S变换。首先根据其运算前提是计算信号的FFT,利用动态测度方法检测出功率谱包络的峰值,以此确定信号的主要频率点;然后对相应的频率点进行不完全S变换,求模得到频率幅值特征向量;最后由这些特征向量进行电能质量扰动的检测。仿真结果表明,提出的算法能明显提高检测速度,更适合实时应用。

The detection methods of power quality based on S-transform usually adopt the feature vectors of S-transform module time-frequency matrix instead of all of the vectors. Accordingly, the computational procedure was analyzed, and the incomplete S-transform was proposed. Firstly, the FFT was performed and dynamics was utilized to describe the envelope of power spectrum so as to detect the valid frequency samples of FFT. Then the incomplete transform was specifically performed for these samples and the modules were calculated so as to get the feature vectors. Finally, these feature vectors were used to detect the power quality disturbance. The simulation results illustrate that the proposed method quickens the detection and is more suited for real time application.