Pitch control of electrohydraulic semi-rotary-actuated wind turbine with actuator and valve fault using generalized power-based exponential rate reaching law sliding mode controller

Abstract

Wind power systems comprise complex components and get exposed to harsh environments due to wind speed variations. Researchers in the domain of wind turbine system control are getting more and more attracted to applying sliding mode control, which emerges as an interesting viable option because of its ease of implementation in practice. Design of suitable nonlinear reaching laws in sliding mode control remains an active domain of research which can simultaneously offer fast convergence and improved control performance. This article develops a detailed model of a proportional valve-controlled semi-rotary-actuated wind turbine with valve deadband, valve fault, and actuator fault. Then, the work proposes a generalized power-based exponential rate reaching law-based sliding mode control for pitch control. Detailed derivation of the reaching time for the proposed sliding mode controller with the reaching law has been presented and its stability analysis has been carried out based on Lyapunov theory. Furthermore, the controller performance has been studied as a passive fault-tolerance controller. Extensive performance evaluations have been carried out using benchmark test signals and real wind data, and the superiority of the proposed controller has been demonstrated in comparison to other state-of-the-art sliding mode controls employing a variety of exponential reaching laws and recently proposed wind turbine pitch controller. The proposed generalized power-based exponential rate reaching law-based sliding mode control was able to achieve the lowest integral absolute error value of 0.0014 with real wind data in comparison to the other competing controllers considered here, that is, exponential reaching law-based sliding mode control, exponential rate reaching law-based sliding mode control, constant proportional rate reaching law-based sliding mode control, enhanced exponential reaching law-based sliding mode control, and improved exponential rate reaching law-based sliding mode control, which were able to achieve integral absolute error values of 0.0086, 0.0065, 0.0050, 0.0034, and 0.0015, respectively. Furthermore, the robustness of the proposed generalized power-based exponential rate reaching law-based sliding mode control has been aptly demonstrated with the instantaneous imposition of fault in the actuator.

Harris hawks optimization tuned exponential reaching law based integral SMC for pitch control of linear hydraulic actuated wind turbines

“…Along with the choice of the switching surface, a very important aspect in the design of Kamboj et al is the choice of a suitable RL so that the state trajectory can be forced to reach the sliding surface in finite time, as quickly as possible, and also to achieve simultaneous reduction in chattering phenomenon. 52 The RL must be designed in such a way that it has to satisfy Lyapunov criterion s s · < 0 . Once the state error vector [ x 1 e , x 2 e ] T reaches the sliding surface, the control law has to try and keep the states on the sliding surface itself so as to it finally converge to zero state at the origin.…”