A chattering-free terminal sliding mode control of direct-drive PMSG for wind generation system

In order to enhance the stability, the control scheme for the wind power generation should have strong robustness. Sliding mode control is powerful to reject disturbance and has good robustness. However, sliding mode control is a fast switching control essentially. While accelerating the speed to reach the sliding surface, it will result in large chattering which can induce high-frequency oscillation of the output of wind power generation system. This paper proposes a novel chattering-free terminal sliding mode control based on the vector control technology, and applies it to control direct driven permanent magnet synchronous generator(PMSG). Speed and dq-axis current regulator are designed to ensure the rotor speed and current to reach the given values in finite time, respectively. The method proposed can estimate the chattering and enhance the system dynamic and static performance. Compared with PI control, the simulation results verify that the speed and current can track the given value more rapidly. Moreover, it has strong robustness to disturbance.