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UBC Theses and Dissertations

A study of power system economic operation Perera, Karannagoda K.Y.W.

Abstract

This thesis is a study of some of the financially important and technically interesting situations which appear in the economic operation of power systems. Static type optimization problems, which arise when a given plant demand is distributed among the running units of that plant, and in thermal power systems, are first considered. For this case, scheduling equations which are valid in the presence of bounds on the plant operating range are derived through the application of Kuhn-Tucker conditions. A dynamic type short-range hydro-thermal problem based essentially according to the currently prevalent formulation of assuming a specified water usage, is extended to include operating range bounds and unit commitment aspects. Pontryagin's maximum principle is found to be useful in obtaining suitable solutions to the extended formulations. For the above dynamic type short-range hydro-thermal problems to be meaningful, the water usage specification should usually be obtained through a careful analysis of long term resource management. With the above view, the overall hydro-thermal economic optimization problem is formulated and the long-range and short-range problems are deduced as its components. This results in a dynamic type long-range component while allowing a static type short-range problem. Among other practical aspects, the stochastic nature of the river flows and the very long and indefinite nature of the period of optimization are taken into account. A mathematical basis for the intuitively appealing concept of water values is developed. As a solution to the long-range problem, an equation which gives the interrelationship of water value functions is derived through the application of the principle of optimality. This equation is shown to be useful in computing water values as a function of reservoir state and time. Finally, complications which arise due to the variation of water head, flow interconnected reservoirs and interruptible consumers are analysed.

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