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UBC Theses and Dissertations

Marginal value controlled reservoir operation Smith, Gerald Keith


Techniques have been developed for coordinating releases from a system of water reservoirs to maximize the expected returns from the system. The system is decomposed into single reservoir subsystems linked by various common demands and interdependent releases and inflows. Demands for firm and secondary energy are considered, and thermal generation can be included in the system. Two basic criteria for reservoir operation have been defined according to principles of economic efficiency. In the operation of each individual reservoir, releases should be increased until the current marginal return equals the marginal loss in future returns and, when several reservoirs supply a common demand, the marginal costs of supply from the reservoirs should be equal. Each single reservoir subsystem is modelled and optimization proceeds on three levels. An iterative procedure calculates the expected value of long-term operation, and then employs dynamic programming to determine releases to maximize that value. Annual inflows are treated as serially independent probabilistic events, and a winter prediction based on snow surveys is assumed to provide complete knowledge of inflows during the coming year. The model is then extended to include reservoirs with interdependent releases and inflows. Releases from upstream reservoirs are influenced by monthly marginal values of water to downstream reservoirs in a release adjustment cycle which converges on sets of optimal releases for all reservoirs in the series. Finally, monthly proportions of the common demands are satisfied by each subsystem, and the optimal proportions which equalize marginal costs of production are found. Computational feasibility and optimization criteria effectiveness were tested with several realistic applications. Dynamlc programming dimensional problems are avoided and computational time increases linearly as reservoirs are added to the system. The present model simulates steady-state operation with annual Inflow as the only variable. Therefore, application is limited to problems involving long-term reservoir operation, or the design of proposed projects. However, modifications are outlined to allow application of the system optimization techniques to transient operation.

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