Power control strategy of wave energy converter with a hybrid double-machine hydraulic energy storage and generating system

Wave energy converters (WEC) with the increasing capacity, which has reached a level of hundreds of kilowatts, would play a role in the connected microgrid. Due to the inherent fluctuation and randomness of wave energy, the unstable output power of WEC is a threat to the power balance of the microgrid. Machines start and stop periodically and the output power changes continuously and significantly. The previous study focused little on the power control of grid-connected WECs. In this paper, a power control strategy is proposed for WECs to achieve stable power output and regulation in various wave conditions. The power control strategy is based on a hybrid double-machine hydraulic energy storage and generating system composed of a controlled unit and an uncontrolled unit. The control strategy enables the stability control and the controllable regulation of power of WEC in various wave conditions. Simulation results of several wave conditions have validated the effect of the power control strategy. The power control strategy would contribute to the extensive deployment of WECs.