Towards real-time operation of interconnected water-energy systems

The role of hydropower generation in power grid operations is set to expand with the increasing integration of variable renewable energy sources like wind and solar. Thus, understanding how hydropower dispatch decisions vary under evolving hydrologic and electricity demand conditions is essential for effective management of water and energy resources. However, modeling hydropower dispatch decisions is challenging because such decisions are influenced by the state of the hydrological and electrical systems in which dams operate. Traditional modeling approaches based on soft coupling are ill-suited to capture these complex dynamics—as well as their feedback mechanisms—because they implement one-way information flow from one model to another. In this study, we introduce a novel model coupling framework that hard-couples a multi-reservoir system model (VIC-Res) with a power system model (PowNet), and thus captures operational decisions based on the states of both systems. Specifically, VIC-Res accounts for the representation and optimization of hydropower reservoirs, while PowNet simulates the unit commitment and economic dispatch of large-scale power systems. The coupler acts as the model orchestrator, managing the sequential exchange of information between models at each time step and checking the convergence of hydropower generated by VIC-Res and PowNet to advance to the next time step. The framework is tested on the Lao PDR-Thailand-Malaysia-Singapore Power Integration Project (LTMS-PIP), which largely relies on the hydropower produced by the Mekong and Chao Phraya river basins. Our modeling effort involves four instances of PowNet (one for each power grid) and two of VIC-Res (one for each basin). Over a 10-year simulation horizon, we show that accounting for the state of both hydrological and electrical systems when dispatching hydopower is key to improve the overall system performance, which we measure in terms of grid operating costs and CO₂ emissions.