Study On Statistical Characteristic Of Electromagnetic Disturbances And Correlation With Immunity Waveform

In recent years, HVDC transmission technology is widely used in our country, more and more scholars began to study on electromagnetic compatibility. Converter is representative of complex electromagnetic environment. This paper contains three parts to analyze transient electromagnetic disturbance of HVDC converter stations. The first part is the theory section of mathematical statistics. Most of the electromagnetic disturbance caused by switch operation, due to switch operation has a strong randomicity, we need to use statistical methods to analysis measured data of electromagnetic disturbance. Before applied statistical methods to data processing, we should test the hypotheses of data. This paper firstly introduces several different kinds of hypothesis test method. And then expounds the traditional statistics method and Bessel method. Because the number of switch operating is limited, electromagnetic disturbance data has the characteristics of small samples, this paper also introduces two small sample statistical method, self-help method (bootstrap) and the stochastic weighted method. By comparing these methods, the text choose stochastic weighted method for the latter statistical studies. The second part firstly introduces the definition of transient electromagnetic disturbance fundamental characteristic parameters, and analize the measurement data, the calculated results were listed in table, and then applies stochastic weighted method to get statistic characteristics of the electromagnetic disturbance. According to the research process, the text proviod an electromagnetic harassment analysis interface. The interface includes two parts, basic characteristic interface and statistical analysis interface. The basic characteristic parameters of electromagnetic disturbance and its probability distribution histogram, time-domain and frequency domain waveforms, the statistical characteristics hypothesis, the frequency domain statistical envelope can be obtained through the interface. The third part of the article expound the definition of signal related, and introduces the autocorrelation function and cross-correlation function. At present, there is no explicit standard for immunity test of the secondary equipment in converter station, we have to estimate the relevancy between actual disturbance characteristics and existed standard in the basis of making statistical analysis of the measurement data so as to modify and add existed standard or develop more suitable standard.