Power Quality Disturbances Analysis And Based On S-Transform

With the rapid development of national economy and scientific technology, a great deal of nonlinear, impact and unsymmetrical load increased significantly in the power system, power quality problems caused more and more serious economic losses, how to effectively reduce the impact of power quality problems has become a research focus of the technology workers. The first step to improve the power quality is the detection, analysis and identification of power quality disturbances. Only to detect power quality problems rapidly and accurately, conduct effectively analysis, and identify the type of disturbances, power quality problems can be controled and governed effectively.This paper systematically analysed the classification, causes and analysis method of power quality problems and established the signal models of power quality disturbances, identified the time of the transient power quality disturbances by using the wavelet transform and analyzed the characteristics of the walvelet transform in processing power quality disturbances, and detected the feature of common power quality disturbances by using the S-transform and analyzed the characteristics of the S-transform in detecting power quality disturbances. The comparison of the wavelet transform and S-transform in dealing with power quality disturbances showed the S-transform was more suitable for the area of power quality disturbances detection and identification.In order to achieve automatic classfication and identification of power quality disturbances, a new method based on S-transform and least square support vector machine was proposed. S-transform was used for extracting the feature vector of power quality disturbances and the least square support vector was used for classification and identification of power quality disturbances. Simulation results showed that the proposed method had an good performance on correct ratio and training speed, and strong resistances to nosies, so it is suitable to classification system for power quality disturbances.Finally, the hardware circuit of the power quality analysis experimental platform based on DSP 5416 was designed. The hardware circuit provided a basis for future analysis and processing of power quality problems. The hardware circuit was made up of the following five parts:data acquisition circuit, data processing circuit, serial communication circuit, power circuit and reset circuit. The data acquisition circuit consisted of signal conditioning circuit and analog-digital conversion circuit. The data processing circuit was mainly composed of the DSP5416 and external storage decives.