Short-term risk-management for hydro-wind-solar hybrid energy system considering hydropower part-load operating characteristics

Francis-type hydropower units operating in part-load region could lead to adverse effects such as decreased turbine efficiency and increased pressure pulsation amplitude. Nowadays, this type of hydropower units is frequently forced to operate in the part-load region due to their complementary operation with uncertain wind and solar power. This poses potential risk to hydro-wind-solar hybrid energy system (HWSHES). However, existing studies have not adequately addressed the risk of hydropower unit operating in part-load region and misestimate the ideal flexible operating range of units. To address the two issues, this work proposes a riskmanagement model for HWSHES considering the hydropower part-load operating characteristics, which is based on the framework of "risk recognition-evaluation-control": (1) Risk recognition: identify and quantify potential operation risk of both power source and power grid in HWSHES; and (2) Risk evaluation: build a triobjective short-term simulation scheduling model to evaluate power sources-power grid risks; (3) Risk control: design a three-stage optimization method for solving the model and effectively controlling risk. A case study of Wudongde hydropower plant, a key project of China's West-to-East power transmission project, in the Jinsha River Basin shows that: (1) The proposed model quantitatively identifies units' part-load risk distribution; (2) The uncertainty of wind and solar is prone to cause the risk of both power shortage and part-load operating in spring and winter; (3) A trade-off between power generation and risk is consistently observed throughout each season; and (4) Implementing the risk-management measures reduces the average part-load operating risk by 57.1% compared with no risk-management. In conclusion, this work contributes to enhancing the riskmanagement capabilities of large-scale HWSHES.