Frequency-Constrained Unit Commitment Considering Typhoon-Induced Wind Farm Cutoff and Grid Islanding Events

In coastal regions of China, offshore wind farm expansion has spurred extensive research to reduce operational costs in power systems with high penetration of wind power. However, frequent extreme weather conditions such as typhoons pose substantial challenges to system stability and security. Previous research has intensively examined the steady-state operations arising from typhoon-induced faults, with a limited emphasis on the transient frequency dynamics inherent to such faults. To address this challenge, this paper proposes a frequency-constrained unit commitment model that can promote energy utilization and improve resilience. The proposed model analyzes uncertainties stemming from transmission line failures and offshore wind generation through typhoon simulations. Two types of power disturbances resulting from typhoon-induced wind farm cutoff and grid islanding events are revealed. In addition, new frequency constraints are defined considering the changes in the topology of the power system. Further, the complex frequency nadir constraints are incorporated into a two-stage stochastic unit commitment model using the piece-wise linearization. Finally, the proposed model is verified by numerical experiments, and the results demonstrate that the proposed model can effectively enhance system resilience under typhoons and improve frequency dynamic characteristics following fault disturbances.