Risk Assessment of Composite Transmission and Substation System with Multi-State Wind Farms

When wind power is integrated into largescale power systems, the multiple-state characteristics of its output can have a significant impact on the safe and stable operation of the power system. A fault in the primary equipment of a substation can lead to a partial power outage at the plant and structural changes in the regional grid, increasing the risk of a regional blackout. This article proposes a state reduction method that takes into account the fitting errors of wind farm power characteristics. The equivalent combined system of transformers and transmission lines is sampled using a two-level Monte Carlo sampling technique, and the system risk indicators are calculated using an AC power flow model. Finally, using the improved IEEE-RTS6 system as an example, the proposed method and model are analyzed and validated, showing the effectiveness of the wind farm multi-state model and the two-level Monte Carlo sampling method.