Coordination Between Wind Turbines and Energy Storage System for Frequency Regulation Participation

As the wind power's penetration level continues to increase, the power grid faces challenges in frequency stability due to the declining inertia and frequency control capability. The use of rotor kinetic energy in frequency regulation can cope with these problems. However, wind turbines could terminate the frequency regulation participation due to insufficient rotor kinetic energy, which leads to a secondary frequency drop. This paper comes up with a coordinated control strategy for wind turbines and an energy storage system during frequency regulation to address the limitation of the rotor kinetic energy. The proposed strategy prioritizes the use of energy storage for frequency regulation. When the energy storage system's capacity is insufficient to meet the requirements of frequency support, the wind turbines participate in the frequency regulation to compensate the power mismatch. When the quasi-steady state frequency is reached, the energy storage assists in the rotor speed's rapid recovery of the wind turbines. Simulations conducted in PowerFactory showed that the proposed strategy has significant advantages in suppressing the secondary frequency drop of the system.