Control strategy for optimal participation of wind farms in primary frequency control

This paper proposes an optimal control strategy for participation of wind farms (WFs) in primary frequency control. In this strategy, we exploit wake interaction in a WF to maximise the total kinetic energy (KE) of the wind turbines´ (WTs´) rotating masses in the WF, and optimally deploy this KE after a frequency event to reduce the frequency nadir, by controlling the rate of change of the rotor speed. The amount of the KE injected into the system by the controller is proportional to the rate of change of frequency (RoCoF) and the frequency deviation after the contingency. By implementing this strategy in a test system with high penetration of wind energy, the stored KE of the WTs in the WF is gradually injected into the system during a frequency excursion. The results show that not only the system frequency nadir is reduced, but also the system frequency is kept relatively uniform for up to 50s.