Abstract :
This paper concentrates on the new arising protection problems in modern distribution grids due to the large-scale penetration of distributed generation (DG). Specifically, hardware-in-the-loop (HIL) simulations for the two major impacts of DG on existing protective schemes, namely protection blinding and sympathetic tripping, will be presented. A simplified five bus distribution network, consisting of two feeders protected by two numerical overcurrent relays, will be simulated in the real time digital simulator (RTDS), established in the electric energy systems laboratory of the National Technical University of Athens. Secondary injection tests will be carried out, by means of the RTDS, via the low-level interface of the digital multifunction relays, which are responsible for the feeders´ protection. Finally, the simulation results will be demonstrated and analyzed.
