Multi-Timescale Coordination of Wind-Solar-Pumped Storage-Battery Energy Systems: Planning, Scheduling, Control, and System Value

The variability of wind and photovoltaic generation requires energy storage systems not only to perform sustained energy shifting but also to respond to rapid power fluctuations. Pumped hydro storage (PHS) and battery energy storage systems (BESSs) exhibit complementary characteristics in addressing these two requirements. However, the separate treatment of capacity planning, dispatch, and control creates a persistent gap between the expected benefits of hybrid configuration and its practical operational feasibility. This paper reviews the system configurations, capacity planning, optimal scheduling, and coordinated control of wind–photovoltaic–pumped hydro–battery energy storage systems, with particular emphasis on how reservoir states, battery state of charge, and unit operating constraints link decisions across different timescales. The associated evaluation metrics and solution methods are also systematically summarized. Existing studies show that allocating regulation power according to fluctuation characteristics can exploit the different response capabilities of PHS and BESS. Nevertheless, persistent power imbalances accumulate into energy deviations, causing the original power-sharing strategy to become increasingly constrained by reservoir water availability and battery energy states. Assigning fast regulation tasks to BESS can reduce frequent power adjustments of PHS, but at the cost of increased battery cycling. Variable-speed operation and hydraulic short-circuit operation can further extend the regulation range of PHS; however, the practically available regulation capability remains constrained by hydraulic head, operating-mode transitions, and hydraulic transients. Consequently, hybrid-storage planning and operational benefits cannot be adequately assessed solely on the basis of static power balance and short-term operating costs. Future research should incorporate dynamic safety boundaries and lifetime-related degradation costs into planning and scheduling decisions, while conducting cross-timescale validation under consistent resource, equipment, and data conditions. Such efforts are necessary to clarify the operating conditions under which hybrid energy storage provides tangible advantages over single-storage solutions and to quantify its practical value in renewable-dominated power systems.