Optimised control approach for frequency-control contribution of variable speed wind turbines

This study proposes a novel control strategy for the provision of an active power reserve for variable-speed wind turbines. The proposed control strategy aims at maximising the rotational kinetic energy by jointly optimising the rotational speed and the pitch angle using differential evolution. The optimisation process takes into account the given frequency support power-reserve margin. Based on the optimisation results, a novel controller strategy is proposed and compared with other existing approaches. This comparison reveals that relative to existing methods at the same de-loaded power, the proposed method yields more rotational kinetic energy released into the system in the event of frequency deviations, thus increasing the frequency stability of the power system.