This paper introduces a three-phase heuristic approach for a large-scale energy management and maintenance scheduling problem. The problem is concerned with scheduling maintenance and refueling for nuclear power plants up to five years into the future, while handling a number of scenarios for future demand and prices. The goal is to minimize the expected total production costs. The first phase of the heuristic solves a simplified constraint programming model of the problem, the second performs a local search, and the third handles overproduction in a greedy fashion. This work was initiated in the context of the ROADEF EURO Challenge 2010, a competition organized jointly by the French Operational Research and Decision Support Society, the European Operational Research Society, and the European utility company Electricite de France. In the concluding phase of the competition our team ranked second in the junior category and sixth overall. After correcting an implementation bug in the program that was submitted for evaluation, our heuristic solves all ten real-life instances, and the solutions obtained are all within 2.45 of the currently best known solutions. The results given here would have ranked first in the original competition.
Setting production levels for power plants is treated in the literature under the term economic dispatch' --- i.e., the problem of dispatching units to producing power in an economic way to minimize production costs. While many different settings are considered, see for example @cite_5 by Chowdhury and Rahman, there are new features in the production planning for nuclear power plants. The new features concern special bounds on production levels when the fuel level is low, which leads to nonlinear constraints. When a type 2 plant's fuel level drops below a given treshold, a decreasing power production level is imposed. Without this constraint the production planning could be solved with linear programming.
@cite_5
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A survey is presented of papers and reports that address various aspects of economic dispatch. The time period considered is 1977-88. Four related areas of economic dispatch are identified and papers published in the general areas of economic dispatch are classified into these. These areas are: optimal power flow, economic dispatch in relation to AGC, dynamic dispatch, and economic dispatch with nonconventional generation sources. >