Response Characteristics And Recognization For Lightning In The Progagation Process Of Transmission Line And Substation

With the rapid economic development of our country,the demand for eclectricity of customer is increasing.the scale of power system becomes larger.Now,constructing strong power grid is advocated. Ensuring safe and reliable power supply is a necessary prerequisite for building a strong grid.But a problem needed solved now is how to ensure safe and reliable power supply.It's also a big challenge.Research shows that lightning stroke is one of the main reasons to cause various kinds of equipment insulation damage in power system. It destroys the normal operation of power system and threatens equipment insulation.Study on response characteristics of lightning wave in propagation process plays a key role in insulation configaration.Lightning protection is an important measure to insure safe and reliable operation of power system.Normal lightning protection measurs are erecting lightning shield line,installing lightning rod, arrester and so on.But lightning trip-out rate doesn't drop after these lightning protection measures are adopted.Because lightning process is so complex that the reasons to cause lightning are various.Nowadays,collection and recording system of overvoltage monitoring device is used to collect and record overvoltage wave.As there are too much overvoltage datas, there are a certain degree of difficulty and workload for experts analyze on field.It requires lightning overvoltage wave characteristc quantity extraction and recognition.This makes it possible to quickly find the point of failure and take some appropriate lightning protection measures.Failure time can be shortened,power supply reliability can be guaranteed.Therefore,lightning overvoltage recognition and response characteristics analysis of lightning wave in the dissemination process play a very important role in safe and reliable operation of power system.In the paper,firstly,the electromagnetic transient simulation software ATP-EMTP is used in 110 k V transmission line and substation modeling and simulation.lightning overvoltage waves are obtained in different positions of substation under different conditions, such as,different types of lightning stroke,different lightning stroke positions,with or without arrester.By comparison with standard lightning wave,the response characteristics of lightning wave in power system are analyzed.Extracting the characteristic quantity of time domain and time frequency domain of measured induced overvoltage and simulation direct lightning overvoltage on transmission line.In time domain,similarity degree of waveforms,interphase peak ratios maximum are extracted.In time frequency domain, characteristc quantity RMS,mean,pulse and so on are extracted based on wavelet transform.Wavelet modulus maxima is used to construct thecharacteristic quantity.for example, wave front polarity and arrester operating time recognize lightning overvoltage.In the processing of recognition,the paper combines traditional binary support vector machine concept and the multi-class support vector machines concept.A multi-layer recursive method is adopted to develop procedure.In order to further improve the recognition accuracy,firstly,normalization method is adopted in data pretreatment,then,integrated using of cross-validation, genetic algorithm, particle swarm optimization algorithm treat optimally the support vector machines,a superior way is chosen to determine SVM parameter.