Design of Microgrid Protection Schemes Using PSCAD/EMTDC and ETAP Programs

Steady-state, harmonics, and transient analysis of a power system by using a detailed simulation model is essential to microgrid operation before the installation of new power facilities, because the microgrid, which is a small-scale independent power grid consisting of distributed resources and an energy storage system, has no choice but to include many inverters consisting of switching devices. Accordingly, in the case of an accident in a microgrid system, various power system simulation tools must be used to calculate the fault current for grid protection components. Specifically, Modelling using Power System Computer Aided Design (PSCAD)/Electro-Magnetic Transient Design and Control (EMTDC) can perform detailed modeling of switching devices into each inverter, and Electrical Transient Analyzer Program (ETAP) can design protection relays. From this perspective, this study designed whole protection components in a microgrid system, including the capacity of switching devices for fault ride through a protective relay and the capacity of the circuit breaker. The parameters of an actual microgrid on the San Cristobal Island, Galapagos, were used to make a detailed simulation model in both PSCAD/EMTDC and ETAP. The capacities of the switching devices were estimated by using PSCAD/EMTDC. Additionally, the rated breaking capacities and the setting values of the protective relay were also calculated from the result of an ETAP simulation.