Grid-connected and islanded operation of a hybrid power system

Rural area often has only one transmission line in connection with main power grid. The safety of critical load cannot be insured. Instead of adding a second transmission line, distributed generation can be installed. In this paper, a hybrid power system is analyzed. It is composed of solar power, wind farm of doubly fed induction generators (DFIG), pumped storage station, residential load and industry load. Both grid connected operation and islanded operation of this hybrid power system are analyzed. A control strategy is proposed to stabilize this power system under islanded condition without the necessary of central master controller. The water tower with back to back voltage source converter (VSC) is operated as a pumped storage station under islanded situation, which controls the frequency and voltage of the islanded power system. Wind farm, solar power, and load contribute to frequency and voltage control of the hybrid power system.