New thermal unit commitment approach using constraint logic programming

The authors propose a constraint logic programming (CLP) algorithm to solve the thermal unit commitment (UC) problem in this paper. The algorithm combines the characteristics of the logic programming with the constraint satisfaction as well as the depth-first branch & bound (B&B) search techniques to provide an efficient and flexible approach to the UC problem. Through the constraint satisfaction techniques, the constraints, which consist of the upper bound on the objective value, are propagated as much as possible to actively reduce the search space of the UC problem in a priori way. Consequently, the optimal solution can be acquired in a very early stage. To demonstrate the effectiveness of the proposed approach, the practical thermal UC problem of Taiwan Power (Taipower) 38-unit system over a 24-hour period is solved by the CLP algorithm implemented in CHIP language. The results obtained are compared with those from the established methods of the dynamic programming (DP), the Lagrangian relaxation (LR) as well as the simulated annealing (SA).