The flexibility of hydroelectric reservoir and pumped storage generation — Application to Switzerland

We investigate the impact that different technical and operational model representations for hydroelectric reservoir and pumped storage power plants have on the market dispatch and annual generation patterns in a techno-economic electricity sector model. The `detailed´ model explicitly accounts for individual plant and reservoir capacity limitations, hydraulic interconnections within cascaded systems, and the seasonal distribution of the usable water resources over the course of a year. The results are compared to two common simplified representations of hydro storage operation: `inflexible´ and `fully flexible´ reservoirs. The three approaches are applied to Switzerland, including the neighboring countries, for the reference year 2012. The model results indicate that the `fully flexible´ approach can be a useful simplification if seasonality is not considered while the `inflexible´ model is infeasible due to missing peak capacity.