Research On Monitoring And Analysis Of Lightning Overvoltage In Substation

In the southern region,lightning frequent areas,frequent lightning accidents,the stable and safe operation of the power grid caused serious damage,substation lightning intrusion wave analysis is helpful to improve the lightning protection level of the power grid.A large number of lightning overvoltage monitoring systems are installed in the substation,and a wavelet transform based lightning overvoltage identification system is developed,which has a high recognition rate.As the waveform of substation intrusion wave is the waveform after transmission line transmission attenuation and deformation,it is necessary to study and analyze the transmission line lightning overvoltage wave process and lightning strike location of the transmission line,to analyze the waveform characteristics of lightning overvoltage.The research group puts forward a kind of based on zno valve piece of partial pressure of lightning overvoltage online monitoring device,the device adopts the zinc oxide valve plates as sensors of overvoltage extraction,through laboratory study,zno valve has a fast response,wide frequency response,good linearity and excellent electrical performance advantages,such as,completely suitable for lightning overvoltage online monitoring.In this paper,wavelet transform is used to extract the characteristic value of overvoltage and support vector machine(SVM)is used for classification.In this paper,the ratio of high and low frequency energy sequence is used as the characteristic value of lightning and operating overvoltage,temporary overvoltage and arc light grounding overvoltage,the similarity is used as the characteristic value of lightning and operating overvoltage,and the energy value of each layer signal is used as the characteristic value of direct strike lightning and induced lightning.In the end,more than 4000 data collected from the substation are classified and identified.The identification rate of this method is as high as 93%,and a large number of waveforms are selected as data support for the analysis of substation intrusion wave characteristics.Paper presents a method of travelling wave based on the improved double end of transmission line lightning location technology,used for statistics on a line by lightning tower or adjacent lines of by lightning overvoltage waveform on both ends of the acquisition,to extract the first time,calculate the time difference,and have been identified by lightning tower measured time take difference divided by the average of double tower wave propagation time of adjacent tower by direct lightning and reference tower distance of implementation of lightning orientation.Through the detection of the measured data,it has a good precision,which provides convenience for the analysis of the characteristics of lightning overvoltage.Through the analysis of the lightning overvoltage waveform extracted from the lightning overvoltage identification system,and combined with the research on the process of the overvoltage wave of the transmission line and the research and analysis of the lightning strike positioning technology,the paper obtains the characteristics of the substation invasion wave and the definition of the lightning invasion wave: Caused by lightning strike phase conductor and earth wire or tower and relatively or insulation flashover and the impact of over-voltage and lightning flashover in phase conductor is not the direct lightning induction lightning overvoltage spread along the route to the substation or power plant of thunder electric wave,the wave front time(T1)0.1 mu s < T1 20 mu s,or less wave tail duration(T2)< 300 mu s,for a single polarity.The waveform extracted from the over-voltage identification system was analyzed and the definition of multi-pulse lightning wave was obtained through statistical analysis.The multi-pulse lightning wave process was as follows: the lightning wave process caused by a single lightning strike that contained more than two monopulse and the interval time of the pulse wave was less than 100 ms.Generally,the two-pulse or three-pulse lightning wave process.