A new method for ground fault line selection in distribution network based on twice regulating zero-sequence voltage

Abstract

Aiming at the problem of low accuracy of single-phase grounding fault line selection in distribution network, a fault line selection method of distribution network based on twice regulating zero-sequence voltage is proposed in this paper. This method use the characteristics that the change law of zero sequence current normal line fault remains unchanged before and after grounding fault occurs, and it always changes in proportion to the system zero sequence voltage, while the change law of zero sequence current of fault feeder changes. By constructing the characteristic function, then regulate zerosequence voltage twice before and after fault occur, and calculated value of the characteristic function of each line, the line with the largest characteristic function value can be determined as a faulty line. This method eliminates the influence of three-phase admittance asymmetry, and has strong line selection ability of high resistance fault. The results of PSCAD simulation show that this method can correctly select the line under different fault conditions, and still has high accuracy in case of high resistance grounding fault.