基于改进S变换的电能质量扰动分类

电能质量扰动信号的分类识别对建立电能质量综合评估体系、选择合理的电能质量治理方案,确保电力系统安全稳定运行和用户的合法用电权益具有重要意义。提出了一种基于改进S变换时频模矩阵的电能质量短时扰动分类新方法。该方法首先根据信号的稳态主导频率确定S变换高斯窗的衰减速度,计算所得时频模矩阵作为各电能质量扰动信号的标准模板;通过比较测试信号改进S变换模矩阵的特定频段与各标准模板之间的相似度,实现扰动分类。在相似度的比较过程中,为了凸显异类模板之间的差别,尤其是电压暂降和暂升、电压缺口和尖峰,提出了能量归一化概念以及分频逐行计算相似度的思想,实现异类模板差异最大化。该方法能够充分挖掘各类扰动信号之间的特征差异,通过简单的相似度比较对扰动进行分类,无需添加辅助分类器。仿真和实测数据的分析表明,该方法分类过程简单,可信度高,抗干扰能力强。

Classification for Power Quality Short Duration Disturbances Based on Generalized S-transform

Classification of power quality disturbances is crucial for establishment of comprehensive power quality assessment systems and selection of the right power quality management measures that will ensure a stable and safe operation of power systems and guarantee users’ rights.This paper proposed a new classification method with respect to power quality short-duration disturbances based on the module matrix of generalized S-transform.Firstly,the delay rate of Gauss window was determined according to the stable frequency constituents of the signals,and then the modulus matrixes of the S-transform were calculated to form the standard templates.The signals could be classified in accordance with the analysis of the similarity between the specific region of the matrix of the test signals and the standard templates.In the process of similarity comparison,in order to enlarge the differences among templates,especially for sag and swell,notch and spike,the concept of normalization and the idea of calculating similarities at different frequencies were proposed,thus maximizing the differences.This method sufficiently excavated the characteristic differences among disturbances;no extra classification process was needed since the similarity comparison could directly give the final results.Simulation and field data analysis showed that this proposed method is easy to be implemented with good noise robustness and high accuracy.