Abstract:

The participation of wind farms in grid frequency regulation is an important measure to address the frequency challenges of the new power system dominated by new energy sources, which have low inertia. During the process of wind farms participating in grid frequency regulation, how to achieve rapid frequency support and ensure the safety of wind turbine operation is of vital importance. Therefore, this paper proposes a hierarchical consistent coordinated frequency regulation control strategy for wind farms. The upper layer is the frequency regulation power optimization allocation of wind farms based on model prediction. By analyzing the electromagnetic and mechanical characteristics of wind turbines participating in frequency regulation, a prediction model of wind farms is established, and the optimization objective of active power allocation to avoid secondary drops and optimize pitch angle is set. The lower layer is the consistency following control. The leading wind turbine receives the power allocation signal from the centralized controller, and other wind turbines achieve the following of the frequency regulation participation degree of the leading wind turbine by exchanging inertia factors with neighboring wind turbines. Simulation results show that this strategy can effectively increase the minimum turbine speed of wind farms participating in frequency regulation, improve the stability of wind farms participating in system frequency regulation, and achieve the following of the frequency regulation participation degree of non-leading wind turbines and leading wind turbines. It avoids the dimension disaster problem of solving the large-scale wind farm frequency regulation optimization model and has good frequency regulation effect, which is of great significance for ensuring the safe operation of the power grid.

Key words: wind farm frequency modulation, pitch angle optimization, wind farm stability, model predictive control, hierarchical control