On the needs to evaluate power grid models’ hydropower scheduling with a river operations model

Production Cost Models (PCMs) simulate the economic dispatch of generators across a large power grid and are used widely by planners to study the reliability of electricity supply. As energy systems transition away from the thermoelectric technologies that have traditionally balanced electricity supply and demand, hydropower and its representation in PCMs is of increasing importance for storage and ramping capabilities. A limitation of PCMs applied to continental power grids with diverse generation portfolios is that hydropower generation is simulated without full consideration of complex river dynamics, leading to possible misrepresentation of grid flexibility and performance.

Using a detailed hydropower model, we evaluate whether the hourly hydropower schedule from a PCM with simplified monthly parameterization can be attained when accounting for realistic river dynamics, such as spill requirements and general water movement through a cascading reservoir system. We perform this hydropower generation test for the “Big 10” hydropower system on the Columbia River (part of the Western Interconnect of the United States), revealing 9% overestimation of available hydropower generation in a PCM solution in an average hydrologic year.

We reflect on the sources of differences with implications onto long term planning practices expected to address uncertainties associated with energy transitions, climate change, environmental regulation and competing water uses.