Simulation knows no bounds: digital real-time simulation for closed-loop testing of numerical communication relays

With the increasing use of numerical protection relays in power systems, from the highest voltage levels, down to consumer voltages, real-time closed-loop simulation is becoming more and more important for development, testing and final acceptance of relays. Especially under the aspect of the increasing use of series compensation, FACTS-elements and HVDC links in all voltage levels, it is evident to consider the power-system transients caused by the switching elements and the high dynamic control