Constant power control of variable speed wind farm for primary frequency control support

The increasing penetration level of wind energy conversion systems (WECSs) into power systems imposes new requirements on the contribution of WECSs in the frequency control system. These requirements can be fulfilled by modifying the conventional control system of WECS. However, special attention should be paid to the frequency response of WECS, which should be high enough to contribute to frequency control, but should not lead to instability of WECS. Since a wind farm contains many turbines, determining the optimal response is very difficult. In this paper, by coordinating the WECSs of a variable speed wind farm, a pre-scheduled power can be tracked. Therefore, the fluctuation of the output power is mitigated; an optimal frequency response is achieved and the stability of WECSs is guaranteed. Simulation results show the capability of the proposed scheme to enable the wind farm tracks a pre-scheduled power and improves frequency control.