New approach with Secant method for solving Unit Commitment problem

Abstract

This paper presents an application of Secant method and Improved pre-prepared power demand (IPPD) table for solving unit commitment (UC) problem. The UC problem is divided into combinatorial sub problem in unit status variables and non-linear programming sub problem in unit output power variables. Initially, IPPD table obtains the unit status information and then the optimal solution is achieved by Secant method at each power demand for 24 hours. The logic is used to obtain the IPPD table is at any power demand, the generating units, which are having low minimum incremental cost (lambda) are operating first and then the remaining generating units are kept in off position until meet the required power demand The proposed method has been tested on a power system having 3 and 10 generating units. The extensive studies have been performed for large-scale power system by considering 20, 40, 60, 80 and 100 generating units. The simulation results of the proposed method were compared with conventional methods such as dynamic programming and lagrangian relaxation method, heuristic methods such as genetic algorithm and simulated annealing and hybrid methods such as LR-GA in terms of solution quality and computational time. The comparison of results of the proposed method with the results of previous published methods shows that the proposed approach provides more qualitative solution with less computational time.