Analysis on Reason for Interphase Short-circuit of 500 kV Alternative Current Compact Transmission Line Caused by Forest Fire

Combining forest fire tripping data in2009to2014 of 500 kV and above voltage grad AC and DC transmission lines ruled by the EHV power transmission company,this paper analyzes characteristics of lines tripping caused by forest fires in aspects of occurrence time,terrain features of failure site and automatic reclosing cases.Compared with DC transmission lines and AC conventional transmission lines,AC compact transmission lines tripping was provided with features of high tripping rate,large proportion of interphase failure,low success rate of automatic reclosing,and so on.In aspects of tower structure and conductor configuration mode,reasons for interphase short-circuit of AC compact transmission lines caused by forest fires were analyzed.It was considered that the main reason for frequent interphase short-circuit was inverted equilateral triangle configuration of the conductor and short interphase distance.