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Optimizing the TVA Reservoir System Using RiverWare

By Suzanne S. Biddle, Proceedings of ASCE World Water & Environmental Resources Congress, Orlando, Florida, May 2001

Abstract: For the past several years, the Tennessee Valley Authority (TVA), U. S. Bureau of Reclamation (USBR), and the University of Colorado’s Center for Advanced Decision Support for Water and Environmental Systems (CADSWES) have partnered to develop a software package called RiverWare for use in modeling multipurpose reservoir systems. RiverWare now offers three different modeling approaches: interactive simulation, rulebased simulation, and optimization. TVA implemented the interactive simulation software in April 1996 for scheduling both power and nonpower reservoirs in the TVA system. In May 2000, TVA implemented optimization modeling for scheduling the reservoir system. Prior to this, optimization modeling had been used in parallel with interactive simulation modeling in scheduling the system for about two years.

The optimization modeling approach takes into account not only the power economics of the hydro system, but also other demands placed on the reservoir system. These demands, which include flood control, navigation, recreation, and water quality, as well as special operations for maintenance and community events, are defined in RiverWare as prioritized constraints. The optimization routine uses goal programming to satisfy all of the constraints in order of priority to the extent possible, and then with any remaining flexibility, optimizes hydropower operations to reduce the total integrated system power supply cost. Hydropower operations are optimized by maximizing the combined value of energy generated during the forecast period and water reserved in storage for future generation.

TVA’s RiverWare optimization model is typically run using 6 hour timesteps for a forecast period of one week. The optimization model can be run several times per day as forecasts of power demands or operational constraints change.

There are several advantages to using RiverWare for optimizing TVA’s reservoir system. First, the optimization model ensures that all of the operational objectives of the reservoir system are met to the extent possible. Then, with the physical and policy constraints satisfied, the timing of hydro generation can be improved to maximize the dollar value of the hydro system to TVA. Finally, RiverWare allows the user great flexibility in scheduling the system. The user can interactively define operating policy in the form of constraints, quickly and easily manipulate input data, and use the objective function value to compare the cost difference of various operating scenarios.

CADSWES - Center for Advanced Decision Support for Water and Environmental Systems -- edit September 8, 2005 -- e-mail webmaster