Implementation and CHIL Testing of a Microgrid Control System

With the growing deployment of microgrids, it is urgent to standardize microgrid control system and the test procedure. In this paper, implementation and testing of a microgrid control system with transition and dispatch function is presented. To alleviate power fluctuations due to renewable energy and control the power at point of interconnection (POI) to zero for planned islanding, tie-line flow control is adopted in grid-connected mode. Voltage-frequency control applied to energy storage system can achieve stable frequency and active re-synchronization in islanded mode. State-of-Charge and power-limiting based dispatch rules are employed in both grid-connected and islanded mode to maintain power balance while reducing fuel consumption. Power balancing upon unplanned islanding is achieved by emergency dispatch. Technique for smooth transition is also adopted to reduce the impact on the breaker at POI and mitigate the disturbance of distributed renewable resources during islanding/reconnection. The control algorithm is implemented with controller hardware-in-the-loop (CHIL) test bench.