Electric utility capacity expansion planning model incorporating power flow equations
Abstract
The electric utility capacity expansion problem is a problem of choosing the type, size and timing of capacity additions to meet a projected demand in the specified planning horizon. Traditionally the problem has been separated into a generator and a separate transmission capacity-expansion problem. A least cost generator only capacity expansion plan would be found and then a transmission line expansion plan to match. This planning paradigm sufficed in the regulated monopoly environment where transmission lines were built mainly for system reliability. In the emerging unregulated environment, transmission lines, in addition to enhancing system reliability are recognized as a significant economic resource, a resource whose economic planning is vital in maintaining a utility's competitive advantage. This has brought about the need for planning models that take into account the location in space of generators and demands and the cost associated with transmitting power among these spatially separated elements. Such models that have recently emerged have relied on the transshipment constraints to capture this flow of power. The model presented in this dissertation improves on this by adding DC power flow equations onto the transshipment formulation. The DC power flow equations provide approximate but linear relationships between the generation and demand levels at nodes and the real power flow through the lines. In addition, the model provides for transmission capacity additions. This is done by grouping the transmission lines into a limited set of alternatives whose network characteristics can be constructed prior to starting the solution search process. The model then chooses the least cost alternative by adding the cost of each alternative to the cost of the least cost generation plan associated with that transmission alternative. Data from the country of Kenya is used to compare the expansion plan from the model with power flow equations with that from the transshipment only model. Five different transmission expansion alternatives are considered. The transmission capacity expansion plans recommended by the two models differ significantly. The total cost of the model with power flow constraints is 19% higher and the model with takes about 2.6 as long to solve.
Degree
Ph.D.
Advisors
Sparrow, Purdue University.
Subject Area
Industrial engineering|Electrical engineering
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