Coordinated power tracking for wind farms participating in secondary frequency regulation

• Proposes a novel two-layer coordinated control framework for wind farm secondary frequency regulation. • Develops an optimization model for presetting EADRC-based pitch controller parameters in real-time scheduling. • Establishes a multi-objective AGC allocation model to minimize tracking error, line losses, and voltage fluctuations. • Validates superior performance via a 352 MW farm case with under 0.05% tracking error. Given the growing significance of wind power integration into power systems, the participation of wind farms in secondary frequency regulation is crucial. This paper proposes a coordinated scheme for WFs to precisely track power commands issued by the automatic generation control (AGC) system. This scheme involves two steps: (a) presetting the controller parameters of each wind turbine generator (WTG) during the real-time scheduling cycle; and (b) allocating the power command from the AGC system to each WTG during the AGC stage. Generally, WTG controllers with fixed parameters cannot achieve strong tracking performance across all operating conditions. Thus, when the base point power is received during real-time scheduling cycle, an optimization model for each WTGs is established to preset the optimal controller parameters. This model aims to minimize the tracking error of the reference signals while considering the refined power regulation dynamics and operational safety constraints of the WTG. Moreover, a power command allocation optimization model incorporating the WF’s power flow constraints is meticulously established to assign optimal power commands to each WTGs during the AGC stage. To minimize the power tracking error at the point of connection, collector line losses, and voltage fluctuations, this model factors in the simplified power dynamics and capacity constraints of WTGs, as well as the voltage and current constraints of the WF. In a 352-MW WF case under a stable/turbulent wind field and step/stochastic load disturbance scenarios, the proposed coordinated power tracking scheme exhibits strong performance. It achieves precise power command tracking with a relative error of less than 0.05% and maintains stable voltage with a fluctuation rate of 0.106%.