Due to the influence of wind speed disturbance, there are some uncertain phenomena in the parameters of the nonlinear wind turbine model with time in an actual working environment. In order to mitigate the side effects of uncertainties in speed models of wind turbines, researchers have designed a variety of controllers in recent years. However, traditional control methods require more knowledge of dynamics. Therefore, based on reinforcement learning and system state data, a robust wind turbine controller that adopts adaptive dynamic programming (ADP) is proposed. The ADP algorithm is a combination of Temporal-Difference (TD) algorithm and actor-critic structure, which can guarantee the rotor speed is stable around the rated value to indirectly adjust the wind energy utilization coefficient by changing the pitch angle in the area of high wind speed and achieve online learning in real-time. In addition, the variation of the pitch angle command of the proposed controller is relatively gradual, which can reduce the energy consumption of the variable pitch actuator, and extend the service life of the equipment. Finally, the wind speed model is simulated by combined wind speed based on Weibull distribution, the comprehensive simulation results show that the proposed controller has better control effect than some existing ones. INDEX TERMS Neural dynamic programming, reinforcement learning, robust control, wind turbine system.

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The increase in speed and system hydraulic pressure may cause major accidents during the transient of load rejection, especially in high-water head hydropower plants. The current study presents a wicket gate step-by-step closure control law, where two guide vanes will be closed asynchronously to reduce the increase in pressure and improve the transient quality of a waterturbine. Compared with the calculated data in the routine closure law, the control law obviously improved the dynamic qualities of the transient in load rejection and decreased the rising hydraulic pressure from the water diversion system of the plant. The proposed control law can replace the role of a surge tank under certain conditions.

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