Safe transition from connection mode to islanding mode in Microgrids

The lack of spinning reserves makes MGs unable to rapidly follow load changes resulting in unbalancing between generation and consumption which in turn causes voltage and frequency deviation from permitted ranges and even to instability. The current paper addresses this stability problem by presenting a novel control system for power converter-based low voltage MGs stabilization. The converter mode operation technique is adopted to improve the operation of MGs in both connecting and islanding modes and also to achieve safe transient between these two modes. The droop control concept is adapted to improve the cooperation between power converters in order to optimally regulate voltage and dispatch the load demand. A battery is used to provide the fast response to load changes and also to compensate unbalancing between load demands and power generation in IM. In addition, a fuzzy based control system is employed to improve the robustness of the control system by adjusting the gains of control loops.