Control strategy of hybrid energy storage system in diesel generator based isolated AC micro-grids

This paper proposes an AC micro-grid structure, which was based on diesel engine, synchronous generator and hybrid energy storage (HES) subsystem, consisting of battery and ultra-capacitor. In system operation, the diesel generator works as the sole voltage source of the micro-grid under islanding mode and the HES cooperate to achieve the power balance of the system. The corresponding energy management strategy was proposed, where the net power of the micro-grid is separated into high and low frequency components. The high frequency part is suppressed by the ultra-capacitor unit, whereas the low frequency part is compensated by the diesel generator and the battery unit together. Through the designed energy management strategy, power balanced of the micro-grid system can be achieved. MATLAB/SIMULINK simulation results under different conditions have verified this proposed micro-grid structure and the proposed energy management strategy. Keywords: AC micro-grid, Diesel generator, Power balance, Ultra-capacitor and battery