Exact output regulation for wind turbine active power control

Abstract

Abstract The recent proliferation of converter-based generators for the grid connection of renewable energy sources has introduced a number of security challenges, including frequency stability. Frequency regulation is achieved through active power generation, requiring power generators to regulate their power output in real time to match a time-varying power command curve specified by the transmission system operator. Control methodologies to enable the turbine power output regulation have been investigated in the wind energy literature for more than a decade. In this paper, we investigate a classical control methodology known as exact output regulation that has been widely used for the twin problems of output regulation and disturbance rejection. We demonstrate how the method may be adapted to achieve output power regulation for a wind turbine. The method assumes that wind preview information from LIDAR measurements is available for the design of the torque and pitch control input signals. To evaluate the potential of the method to improve wind turbine capability for the provision of frequency regulation services, we compare its performance with that of two baseline controllers, one pitch-based and one torque-based, for the tracking of a specified time-varying power command signal. Our simulations show that the proposed methodology can substantially improve the output power regulation, reduce fatigue loads and also reduce actuator usage, relative to the baseline controllers.