Operation of Directional Overcurrent Protection in Microgrids

This paper aims to raise awareness of the different ways of evaluating fault current direction using directional overcurrent protective relays. A comparison has been made for currently used protective relays from SEL and ABB in distribution networks. It is for their further use in microgrids that it is necessary to know what algorithm they use. Published articles in this area of research indicate that the current protection system cannot be used in microgrids and will be replaced by a new one. The most problematic part of the use of overcurrent protection in microgrids is the application of renewable power sources, which are mostly connected through inverters whose short-circuit current contribution is around 1.4 multiples of the rated value of the nominal current.