A Compensation Power Control Strategy for DFIG and PMSG in a Wind–PV–Hydro Hybrid System

Abstract

When a short-term power fluctuation caused by photovoltaic (PV) array occurs in a wind–PV–hydro hybrid system, the traditional hydro generator cannot suppress the fluctuation perfectly. The reason is that its response speed is not as fast as that of the stored energy unit equipped with electronic devices. However, the wind turbine based on either doubly fed induction wind generator (DFIG) or permanent magnetic synchronous generator (PMSG) has the advantage of a quicker regulation speed and the kinetic energy stored in the rotor can be used to quickly compensate the short-term power fluctuation. This paper proposes a new approach to take advantage of the rapidity of wind turbine to improve the stability of total output in a hybrid system. In the active power control loop of DFIG and PMSG, the deviation of total output to be compensated is added to the reference of power output, so that the wind turbine can adjust its output according to the fluctuation of total output, which consequently can stabilize the output. Case studies under different system operation conditions are presented, and the results show that the proposed control strategy can make the output more stable, which verifies the effectiveness.