A Hierarchical Inertial Control Scheme for Multiple Wind Farms With BESSs Based on ADMM

Wind farms (WFs) can provide inertial response to power systems through synthetic inertial control. In large scale power systems with high penetration level of wind power, WFs are located in different areas with different wind speed conditions, and it is necessary to coordinate them during inertial control. This paper proposes a hierarchical inertial control (HIC) scheme consisting of a WF level coordination and a wind turbine (WT)/battery energy storage system (BESS) level coordination in active power outputs during inertial control process, in order to improve the system frequency response and reduce the operational cost of each WF. First, the optimal active power references of multiple WFs during inertial control are determined to improve the frequency nadir of the system. Second, the active power references of the WTs/BESS of each WF is optimized to avoid over-deceleration of the WTs' rotor, and minimize the wind energy loss and degradation cost of the BESS. The optimization is achieved by developing a model predictive control (MPC) problem and solving it using the alternating direction method of multipliers (ADMM) to improve the computation efficiency. Simulations on 5 WFs integrated into IEEE 39-bus system were conducted to validate the proposed HIC scheme.