A novel approach for robust control design of hidden synthetic inertia for variable speed wind turbines

Abstract

This work presents a novel design methodology for hidden synthetic inertia control of variable speed wind turbines that considers the compromise between grid frequency response and operating limits of the wind turbine states. Two state space design strategies are proposed: one based on H∞ robust control with dynamic output feedback; and other based on H∞ static state feedback control; both strategies operate as supplementary controllers. The study was carried out on simulation with dynamic mathematical modeling of a variable speed wind turbine and an isolated system with conventional power plants, aiming to evaluate the grid frequency response to load-generation disturbances and wind speed variations. The proposed control strategies are compared with two topologies: without wind turbine frequency control and another with synthetic inertia contribution by Proportional-Derivative control. The proposed strategies allow to optimize performance of synthetic inertia control in accordance with wind turbine operating limits. H∞-based topologies presented greater attenuation of the impacts of load-generation disturbances on the frequency response, and also minimizes a cost function based on H2 norm of the frequency signal in comparison with other controllers, thus providing better performance against reference variations and changes of operation point.