Protection coordination in grid connected & islanded modes of micro-grid operations

Increasing penetration level of distributed generation sources in the power distribution system causes number of operational and control issues. Coordinated operation and control with the help of effective communication protocol forms the concept of smart grid and micro grid. When injection of distributed generation sources are more than 20-30 percentage of total system capacity cause the mal-operation of existing overcurrent protection coordination. In this paper an expert based adaptive overcurrent protection coordination approach is presented with restores the overcurrent relay coordination as per the changing fault current contribution from the distributed generation sources. Micro-grid model is simulated in MATLAB and relay setting are optimised with the help of robust and fast covariance mean evolution strategy based optimization algorithm.