Distance Protection with Fault Impedance Compensation for Distribution Network with DG

Impedance type relays are a promising alternative to overcurrent protection in distribution networks with dispersed generation (DG) due to their inherent directionality and fault current independence. At the same time, the biggest problem in their application is underreaching issues caused by non-zero fault impedances. This work proposes a universal compensation strategy aiming at eliminating errors produced by fault impedances and infeed currents from DG. The method is tested on a model of an actual network in PSCADTM/EMTDCTM. It demonstrates good performance for interphase faults and gives possibilities for fault location. The developed approach helps to improve dependability of impedance relaying in distribution networks with DG and overall quality of power supply.