Study On Transient Power Quality Based On S-transform

With the rapid increasing of devices sensitive to power quality, More and more attentions are paid to transient power quality problems by power unit and consumers. The study of transient power quality problems takes important part in the detection and analyzing of power quality. So discussing that how to detect and classify the power quality disturbances automatically and accurately is the core point of the problems, it's also the necessary process to construct integrated power quality monitoring system and the premise to control power quality problems.This paper reviews the methods used in transient power quality disturbance analysis firstly, and secondly, that the characteristics and the causes of different transient power quality disturbance are analyzed in detail. Thirdly, based on the S-transform, that the detection, classification methods and the classification method of the voltage sag sources in transient power quality disturbance are proposed.Based on LabVIEW7.0, the paper achieves the automatic detection and classification of ten kinds of transient power quality disturbances by using of constructing simple rule-based tree after the analysis of various disturbances S-transform statistical information, and its process is"data processing– extracting characteristics– rule-based tree– outputting the result". Then the work of the automatic classification of seven kinds of voltage sag sources is realized, by means of the wave graph analysis of various disturbance sources and the excellent extracting characteristics based on the S-transform.The results of simulation show that the detection method proposed could detect various transient power quality disturbances quickly and correctly; the classification method possesses high recognition rate, recognizing more kinds of disturbances, strong resistance to noises, simple rule-based classification tree and also is easy to be achieved; the classification method of the sources of voltage sag is effective.