Protection of Microgrid Using Coordinated Directional Overcurrent and Undervoltage Relay

The power system protection is the most vital concern to be addressed with the proliferation of DG. Integration of DG changes the direction of power flow and level of fault current that makes protection of microgrid very challenging. DG integrated through power electronics (PE) converters can decrease or increase fault current level, based upon the location of DG. Due to this existing protection schemes may not work properly or fails to operate. Thus, the selection and design of proper protection scheme is very important for maintaining system reliability. The presented work is based upon the various microgrid protection issues and to implement a suitable protection scheme which works in both grids connected and islanded mode. A novel technique is proposed to design and analysis undervoltage and directional overcurrent relays protection with suitable settings for the microgrid system. Proper relay coordination for protection of microgrid in both islanding and grid connected modes of operation is shown. Simulation studies is carried out on ETAP software.