Full-Operating-Condition Modeling and Multi-Mode Coordinated Control Strategies for Fixed-Speed and Doubly Fed Variable-Speed Pumped-Storage Units

Abstract

High-penetration renewable energy systems impose increasingly stringent requirements on the rapid cross-mode regulation capability of pumped-storage hydropower units. However, during transitions among generating, pumping, shutdown, and start-up modes, the hydraulic, mechanical, and electromagnetic subsystems exhibit substantially different dynamic time scales. Consequently, conventional time-scheduled mode-transition control strategies struggle to simultaneously accommodate hydraulic safety constraints, fast electromagnetic responses, and continuous evolution of unit operating states. To address these challenges, this paper develops full-operating-condition hydraulic–mechanical–electromagnetic coupled dynamic models for fixed-speed pumped-storage (FSPS) and doubly fed variable-speed pumped-storage (VSPS) units. The models integrate the complete characteristic curves of pump-turbines, elastic water-hammer dynamics, nonlinear governing systems, and electrical machine electromagnetic dynamics. A Suter transformation is employed to obtain continuous numerical representations of the nonlinear hydraulic characteristics in the reverse S-shaped and hump regions. Building upon these models, a state-conditioned multi-mode coordinated control strategy is proposed, integrating discrete operating-mode supervision and continuous closed-loop regulation within a unified control architecture. Rotor speed, discharge, guide-vane opening, and hydraulic operating states are incorporated into the mode-transition criteria to ensure continuous state evolution throughout operating-mode transitions. Furthermore, a unified performance evaluation framework is established to investigate and compare the dynamic characteristics of FSPS and VSPS units under different operating conditions and mode-transition scenarios. In the investigated load-rejection cases, the maximum relative rotor-speed rises are approximately 36.3% for FSPS and 14.0% for VSPS. These case-specific values do not establish a matched-condition performance improvement because the initial duties and closure schedules differ. These scenario-specific results illustrate how the proposed framework unifies full-operating-condition multiphysics modeling with cross-mode continuous–discrete coordinated control, providing a theoretical foundation for dynamic performance assessment and coordinated control design of fixed-speed and variable-speed pumped-storage units under complex operating conditions.

The authors' abstract, as published at the source. Processes, 2026 · DOI ↗