Power spectrum of fault phase voltage based single-phase adaptive reclosure

When single phase earth fault occurs in EHV/UHV (extra high voltage/ ultra high voltage) transmission line, distinguishing the type of fault is the guarantee of application of single phase adaptive reclosure.This paper analyzes the characteristic of the recovery voltage when single phase earth fault occurs in EHV/UHV transmission line with shunt reactor. The results show that recovery voltage of temporary fault contains the components of power frequency and resonant frequency, while the recovery voltage of permanent fault only contains power frequency component. According to the different frequency characteristics of recovery voltage, a new method based on power spectrum to distinguish the temporary faults from permanent faults in EHV/UHV transmission lines is proposed. Using the distribution of spectral line nearby the power frequency in power spectrum, this method can distinguish the types of fault. The criterion which doesn´t need high frequency contents is prone to set and realize. Simulations have been carried out by MATLAB/ SIMULINK and the power spectrums have been calculated. The results show that the proposed method is exact and feasible.