Framework for short-term hydropower cascade–station–unit integrated multi-objective scheduling: Considering unit safety and economic efficiency

Abstract

Short-term hydropower scheduling primarily focuses on maximizing economic benefits, and the hydroelectric generating unit, as the primary component responsible for power generation, has become increasingly important given the growth in installed capacity. Consequently, current research has focused on hydro-unit commitment, particularly in terms of its safety status. This study addressed the challenges of sudden load changes and multi-session benefit optimization in cascade power stations, developing a short-term multi-objective optimization model that considers both cascade energy storage and unit safety benefits. First, the work proposed methods to evaluate unit operation status and priority, integrating it into the unit safety objectives. Subsequently, a mixed-integer linear programming model was constructed, incorporating a dynamic variable constraint corridor strategy based on the initial state to narrow the solution space and improve the solving efficiency. The model was validated through case studies involving the scheduling of the Three Gorges–Gezhouba and Xiluodu-Xiangjiaba cascade power stations on the Yangtze River in China, comparing the computational effects in four operational scenarios: drawdown, impoundment, maintenance, and emergency. The results show that: (1) The proposed single-period model effectively reduced the units start/stop frequencies under load fluctuations. (2) In multi-period optimization scheduling, the model enhanced the energy storage benefits at the end of scheduling and optimized the safe operation of the units. (3) A competitive relationship exists between cascade economic benefits and unit safety objectives.