Medium-term optimization of pumped hydro storage with stochastic intrastage subproblems

This paper presents a medium-term self-scheduling of pumped hydro storage plants. A decomposition of the problem into inter- and intrastage subproblems, where the intrastage problems themselves are formulated as multi-stage stochastic programs, allows the detailed consideration of short-term flexibility. The method is presented together with three alternative approaches, where the short-term flexibility is considered differently: (1) with aggregated peak and off-peak prices, (2) with price duration curves and (3) with deterministic intrastage subproblems. The approaches are compared and evaluated in a Monte Carlo operation simulation study. The study is performed on a realistic hydro power plant with consideration of revenue from ancillary services.