Wind Turbine Envelope Riding

This paper presents a power control algorithm that aims at keeping a wind turbine within its safe loading envelope at all times. An online optimization procedure is used to find those wind speed variations that would lead the wind turbine response to approach the border of the safe operating region, without crossing it. The optimization result is then compared to the actual wind speed to detect if there is a danger of excessive loading, in which case the power reference is adjusted accordingly. The method is the extension of a previously described optimal soft cut-out strategy, which is here modified in order to control the machine not only at high wind speeds but across the entire operating speed range. The proposed control strategy is verified using a high-fidelity aeroservoelastic simulation model, demonstrating its ability in riding the operating envelope, thereby keeping the wind turbine within safe limits at all times.