Improvement of overcurrent protection considering distribution systems with distributed generation

This paper presents the impact caused by the Distributed Generators (DGs) on the Overcurrent Relays (ORs) performance for Distribution Systems (DSs) protection, as well as an analysis of the resulting disturbances associated to power quality. A real-time digital simulator was used to model the base test system and to perform the analysis. The base test system is composed by a DG, based on a solar farm, connected to a typical DS substation. The simulations consist of several fault scenarios, in order to show the OR misoperation. The voltage unbalances observed with the tests were used to improve the overcurrent function. Closed loop simulation was performed with a commercial relay to validate the proposed protection function.