Overcurrent relay coordination for micro-grid with different operating conditions

The dynamic behavior of micro-grid imposes serious challenges to the design of the protection system. The fault current magnitude and direction changes significantly with variations in the operating conditions which may leads to failure of protection system and non-selective operation. To alleviate the problems, this paper proposes an effective relay coordination using Genetic Algorithm (GA) considering different topology and operating modes of the micro-grid. The proposed coordination enables the overcurrent relays to update their current setting according to the operating conditions to achieve the minimum possible operating times while maintaining the coordination criteria between the primary and backup relays. Extensive test results with both synchronous and inverter based DGs and operating conditions indicate the ability of the proposed relay coordination in devising an effective and reliable protection measure for microgrid.