Secondary Arc Spectrum Characteristics on EHV Transmission Lines

On extra-high-voltage (EHV) transmission lines,the existence of secondary arc impacts on the stable operation of system. The effectiveness of single-pole autoreclosure (SPAR) in maintaining power system stability is largely determined by the speed with which secondary arc extinction and autoreclosure can be achieved. So it is necessary to further study secondary arc. One-terminal input data were processed and determined (if and when the secondary arc following clearing of a single-phase-to-ground fault has disappeared. Realistic simulation techniques are of obvious importance in the design of systems employing. We adopted total harmonic distortion (THD) to judge the status of arc. First,the simulation model of secondary arc was established by the ATPdraw software. Then,faulted phase voltage and secondary arc were simulated in different close angle. Finally,the spectrum characteristics and harmonic content of faulted phase were analyzed,at the same time. THD was obtained by Fourier algorithm. The simulation results show that THD of faulted phase voltage decreases as close angle in every fourth cycle,providing the basis for judging state of arc by using harmonic content of faulted phase voltage. The analysis of spectrum characteristics of harmonic content is of significance in the design of choosing insulation materials and insulation structure.