LIDAR-based FX-RLS feedforward control for wind turbine load mitigation

An adaptive feedforward controller based on a filtered-x recursive least square (FX-RLS) algorithm and a non adaptive feedforward controller based on a zero-phase-error tracking control (ZPETC) technique have been designed to augment a collective pitch proportional-integral (PI) feedback controller for wind turbine rotor speed regulation and component load reduction when the turbine is operating in above rated wind speed. The feedforward controllers use wind speed measurements provided by a commercial light detection and ranging (LIDAR) system. Simulations show that augmenting the baseline PI feedback control with ZPETC feedforward control improves the blade loads but worsens the tower loads. The FX-RLS feedforward algorithm gives better performance than both the baseline PI feedback and the ZPETC feedforward in both tower (fore-aft and side-to-side) and blade (flapwise and edgewise) bending moment mitigation, even with a realistic 1 Hz LIDAR data update rate.