Modified dynamic programming based unit commitment technique

Abstract

This paper represents a modified dynamic programming solution to the unit commitment (UC) problem. The UC is a complex decision-making process because of multiple constraints which may not be violated while finding the optimal or suboptimal commitment schedule. There are many methods to solve the UC problem gradually. So, before we present our method, we will show the drawbacks of the standard dynamic programming methods which use general purpose optimization techniques to the UC problem. The priority list method, the lagrange relaxation and the mixed integer linear programming (MILP) are possible to apply to a real power system for performing the unit commitment. However, by using these methods, we could not get an optimal solution but only a suboptimal silution. Therefore we propose to get an optimal solution by using dynamic programming. Performing dynamic programming takes a lot of simulation time, so it is not optimal to use in a real power system for performing the unit commitment. Therefore, we need a modified dynamic programming method to satisfy both the simulated and the real power system to get the optimal solution. For those not familiar with UC problem, we introduce the constraints, production cost and start-up cost. The goal of the objective function is in cost minimization, so we use the economic dispatch using the lambda iteration method when we calculate the production costs. Finally, we compare the UC solution by using both methods.