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.