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

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 risk-management 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 tri-objective 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 risk-management capabilities of large-scale HWSHES.