A simple approach to predictive control for small wind turbines with an application to stress alleviation

Abstract

Small wind turbines (SWT) generally operate under unsupervised conditions, oftenexposed to varying environmental conditions including high turbulence and gust levels. Whiletraditional SWT control focuses on maximum power point tracking (MPPT), a reliabilityorienteddesign should also consider an appropriate strategy for mitigating mechanical loadsin the rotor and other structural elements. In the present work, a predictive control basedstrategy is presented which allows to upgrade an existing small wind system by implementing asupervisory control considering a joint optimization of output power and the stress in the rotorblades. Innovations include a simple yet robust implementation of an adaptive predictive controlfor a custom-designed rectier and the construction of a compound objective function throughadvanced beam modelling of the rotor blades. The proposed strategy has been demonstratedexperimentally using a laboratory test bench, showing a signicant reduction of rotor stresswhile maintaining the SWT near optimal power extraction conditions.