A blade-pitch controller for a large wind turbine generator in the presence of time-varying delay and polytopic uncertainty

A pitch-regulated wind turbine has an exclusive pitch activator for every single blade, and it is possible to send various pitch angle demands to each blade. They possess a controller to perform this task, and the problem of delay-dependent robust stability with polytopic-type uncertainties of these time-varying delay systems must be resolved. This paper deals with the dynamic output feedback robust stabilization of the large wind turbine generator in the presence of time-varying delay and polytopic uncertainty. Two critical assumptions are considered for the turbine model involving the model's parameters are uncertain, and the blade-pitch control input actuates by a time-varying unknown delay parameter. A set of intervals is considered for the uncertain and delay parameters, which are assumed to be given and known. Then, a novel algorithm is proposed to design a proper controller for this system based on the Lyapunov-Krasovskii functional approach. The proposed controller simultaneously compensates for the effects of both delay parameters and uncertain parameters. To validate the results in this study, two simulation examples are proposed considering different turbines to compare the performance of the designed controller with previously designed controllers. The results reveal the superiority of the proposed controller compared to the existing controller.