Optimization of the Mid-Columbia Hydropower System

This thesis is about the optimization of the Mid-Columbia hydropower system, which is comprised of seven cascaded hydropower projects on the Columbia River. It is the largest system of its kind in the United States, and it possesses unique qualities that make it useful to power system operators and important for the integration of variable and intermittent wind and solar generation. This research formulates real-time and day-ahead optimization programs to plan cascade operations and coordinate hydro and wind resources. These programs are used to evaluate the potential benefits of real-time optimization (with and without wind firming) and hydro-wind coordination with day-ahead replanning and to estimate the battery-like properties of the Mid-Columbia system when it is used to balance wind variability. The system is simulated and tested using a multi-year wind and hydropower dataset that has been compiled from publicly available resources and estimated using bespoke software tools. Our results demonstrate that real-time optimization can increase hydraulic potential by 0.74 percent and stored energy by 0.68 percent. The power capacity of the Mid-Columbia hydropower battery is +/- 3000 and +/- 750 megawatts with and without replanning, respectively. Round-trip conversion efficiency exceeds 80 percent, and energy storage capacity is several tens of gigawatt-hours. These estimates may be too conservative or too optimistic depending on modeling assumptions, and they are subject to significant uncertainty. The primary factor inhibiting the performance of the hydropower battery was the maximum generation capacity of the hydropower system