Doubly-fed induction generator enabled power generation in ocean wave energy conversion system

This paper proposes a power architecture to utilize doubly-fed induction generator (DFIG) for power generation from oscillating wave energy converter (WEC). Unlike in wind energy conversion system, the stator circuit of the DFIG can not be tied directly with the grid in wave energy conversion system (WECS). In WECS, the speed of the DFIG oscillates from one direction to another. Due to the change of direction of the speed, the stator of the DFIG is proposed to be connected with the grid with switched phase sequence. Also, at low operating speed the DFIG slip speed increases which requires higher voltage rating of the rotor side converter. Therefore, to operate the DFIG with limited rotor side voltage the stator circuit is short circuited at low speed. With these modifications, the DFIG based power architecture is proposed to generate power from WECS. In this paper, the overall hardware and control architecture and system operation are presented. System operation is validated through simulation in MATLAB-Simulink platform. For simulation of the whole system, a WEC model is considered.