Pitch Angle Regulation of Floating Wind Turbines with Dynamic Uncertainty and External Disturbances

Abstract

This paper addresses the problem of pitch angleregulation of floating wind turbines with the presence ofdynamic uncertainty and unknown disturbances usuallyencountered in offshore wind turbines, where two control lawsare derived for two different cases to continuously achieve zeropitch angle for the floating turbine. In the first case, the timevaryingunknown coefficients that characterize the turbine'sdynamics are assumed reasonably bounded by known functions,where robust controller is designed in terms of these knownfunctions to achieve zero pitch angle for the turbine withexponential rate of convergence. While in the second case, theturbine's dynamics are considered to be characterized byunknown coefficients of unknown bounds. In this case, a slidingmodeadaptive controller is constructed in terms of estimatedvalues for the unknown coefficients, where these values arecontinuously updated by adaptive laws associated with theproposed controller to ensure asymptotic convergence to zerofor the turbine's pitch angle. Simulations are performed todemonstrate the validity of the proposed controllers to achievethe required regulation objective.