An equivalencing technique for solving the large-scale thermal unit commitment problem

This chapter presents a new efficient solution approach for solving the unit commitment schedule of thermal generation units of a realistic large scale power system. We base the approach on cardinality reduction by the generator equivalencing concept. This concept reduces the number of units in the large-scale power system to the lowest possible number based on the units' fuel/generation cost and other physical characteristics, such as minimum up and down time, etc. with units having similar (almost the same) characteristics form one group. The reduced system consists of only each group of representative units and is first solved by the modified dynamic programming technique (one of the new solution methods developed by the authors). Another option is to use any of the standard unit commitment solution techniques. We obtain the overall solution to the original unit commitment problem of the entire system by un-crunching the solved reduced system based on certain rules. This chapter also presents test results for real-life systems of up to 79 units and comparisons with results obtained using Lagrangian relaxation and truncated dynamic programming (DP-TC).