High Voltage Transmission Lines Lightning Over-voltage Recognition

In the power system,the transmission distance of the high voltage transmission line is very long which may go through different topography and high ground distance.Therefore,the probability of the lightning to the high voltage transmission line is much larger than that of other electric power equipment.Therefore,the transmission line lightning overvoltage has become one of the important factors affecting the safe operation of power grid.There are two kinds of high-voltage transmission line's lightning overvoltage.one is the induction lightning over voltage,the other is the direct lightning over voltage,direct lightning over voltage is divided into counterattack and wound.High-voltage transmission lines are subject to lightning,then the line insulation impact flashover,and it convertes to the power frequency arc,causing the transmission line trip.Therefore,the transmission line lightning overvoltage to identify can be generated by the different lightning over the corresponding lightning protection measures to prevent the occurrence of lightning accidents,improve the transmission line power supply reliability.In the lightning protection construction of the power grid,the identification of the lightning overvoltage has a guiding effect on the lightning protection architecture,which provides a reliable basis for the relay protection setting,and has important reference significance for the location and prediction of the transmission line fault.In this paper,the formation mechanism of lightning current is expounded,and the reason of the lightning current acting on the transmission line is analyzed by the analysis method of the power system transient.The lightning stripping overvoltage of the transmission line is classified and identified.The simulation model is obtained by using ATP-EMTP of the power system electromagnetic transient software,and the corresponding simulation model is obtained.The lightning overvoltage of each type of transmission line is simulated with the example,and the transient overvoltage signal under different fault types is obtained.On this basis,combined with the powerful computing power of Matlab software to deal with and analyze the lightning transient signal,according to the wavelet transform to extract the seven features of the degree of distinction,so the transmission line lightning overvoltage classification and recognition.After extracting the feature quantity in different situations,the comprehensive criterion of recognition is obtained.At the same time,according to the experience accumulated in the long run of the power grid,the criterion is modified appropriately and the lightning overvoltage detected by the corresponding fault type is set,Verify that the method has a certain adaptability.