Modelling on Optimal Scheduling of Variable-Speed Pumped Storage Units in Novel Electric Power Systems

This study conducts an analysis of the operational characteristics of fixed-speed and variable-speed pumped storage units and establishes a joint scheduling model for pumped storage units and other types of units based on mixed-integer linear optimization. The model considers conventional pumped storage unit constraints such as unit operating conditions, reservoir capacity, and cycle type, while also addressing the issues of frequent start-stop operations and losses incurred by operation beyond stable regions. Utilizing the CPLEX solver to solve the model, empirical case studies within provincial power grids demonstrate that the model effectively schedules the output of fixed-speed and variable-speed pumped storage units while considering the economic lifespan of units. This scheduling optimally leverages the units for peak shaving, valley filling, and renewable energy integration. Variable-speed units, due to their flexible adjustment capabilities in both power generation and pumping modes, contribute significantly to improving the operational conditions of other units within the system and facilitating renewable energy integration.