Identification Of Transient Fault On Series Compensated Line

Single-phase grounding fault of EHV transmission line is mainly divided into two states:permanent fault and transient fault. Transient fault is usually occurs in these two kinds offaults, and the reclosing technique can improve the stability and reliability of power system.But if it reclosed in permanent fault, it will impact the system again and damage the workcondition of breaker. Therefore, judging the single-phase grounding fault before reclosing torealize adaptive reclosure is particularly important. The series compensation transmission lineis given more attention because it can improve the transmission power, reduce network lossesand it also has certain economic. Therefore, it is necessary to judge the nature of fault in seriescompensated EHV transmission line.This paper first researches the shunt reactor and series capacitor, and then establishes thesimulation model of EHV series compensated line. As the amplitude of arc current is theimportant factor to determine the ability of arc extinguish, so arc current of steady andtransient state in series compensated transmission line is simulated. Through the simulation itcan obtain that the low frequency component existed in the transient process of the arc currentwill increase the transient value of arc current and affect the extinction of arc. Therefore somemeasures must be found out to inhibition of the arc current in order to ensure the arc canself-extinguish smoothly.The frequency components of recovery voltage are calculated after the laplace transformof EHV series compensated transmission line model. Through MATLAB/SIMULINKsimulation to observe the frequency difference between the series compensation and withoutseries compensation line to determine the nature of single-phase ground fault.Then research the wavelet transform properties especially the multi-resolution analysisof wavelet transformation, and summary the extraction method of the wavelet frequency bandenergy in order to used in the identification of transient fault. Finally the low frequencyenergy in recovery voltage of EHV transmission line is calculated, according to the wavelet low frequency energy,we can obtained the method which can distinguish the transient andpermanent fault in parallel compensation EHV line.