Research On Distribution Network Power Quality Analysis Algorithm And Its Application

With the widespread use of power electronic devices in distribution network,the quality of power supply is reduced,which affects the stability and economy of power system,therefore,the power of accurate and reliable quality analysis and evaluation on the safety and economic operation of power system is very important.In this thesis,the main research work of power quality parameter detection,power quality evaluation and power load forecasting method in distribution network is studied.In order to solve the problem of high complexity and inaccurate positioning in the classification method of distribution network power quality disturbance,a method of identifying and detecting S transform matrix and classification rule tree is proposed.It is through the signal S transform and extract four features criterion,then the classification rules tree based on the formation of self recognition disturbance classification;then the amplitude envelope method and amplitude and mean square amplitude detection method,the change of the disturbance signal and disturbance time.The simulation results show that the proposed method can identify and detect the transient disturbance signal with a low complexity,and the recognition accuracy can reach more than 93%,and the detection error is less than 2%,which verifies the reliability and accuracy of the method.In order to solve the problem that the weight of the single index is caused by the single weight and the limitation in the power quality assessment,a method of gray correlation power quality assessment based on subjective and objective weights is proposed.To determine the weight of the power quality index through the combination weighting method,FAHP method and entropy method to determine the subjective and objective weight;in addition,according to the grey correlation coefficient of grey correlation analysis to determine the index weight,comprehensive value and complete the comprehensive evaluation and weighted grey correlation coefficient.The example analysis shows that the comprehensive weight method can realize the accurate classification of the power quality of each observation point of the distribution network.In order to verify the performance of the S mode matrix detection method and the grey correlation evaluation method,the power quality parameters of a regional distribution network in Guangdong power grid are used for transient detection and comprehensive evaluation.The example analysis shows that the application of S matrix model can accurately and effectively achieve the power detection and identification,classification and quality parameters of the transient disturbance;using gray relational comprehensive evaluation method can realize the comprehensive evaluation of power quality and accurate classification.