A communication based infeed correction method for distance protection in distribution systems

Due to the increasing penetration of Distributed Generation (DG) units in the power grid, traditional protection philosophies in distribution systems need to be updated. Distance protection offers an interesting choice in microgrid protection since it is independent of variations in source impedance. However, there are several constraints in applying conventional distance protection on the distribution side. If a DG is present between the fault point and measurement location, the resultant infeed effect might lead the relay to incorrectly infer that the fault is located at a higher time grading zone. This paper proposes a simple communication based scheme for accurately estimating the distance to fault in presence of infeeds. The performance of the method is demonstrated with a microgrid model in MATLAB/Simulink.