Analysis of unit commitment problem through Lagrange relaxation and priority listing method

This paper shows how the Lagrange Relaxation dual optimization algorithm is incorporated in solving a thermal unit commitment problem. The Lagrange relaxation procedure solves the unit commitment problem by temporarily relaxing the coupling constraints and solving the problem as if they do not exist. The performance of this technique is tested by running the algorithm on MATLAB using a 10-unit system with a 24-hour load requirement data. The same problem is solved using Priority listing method on MATLAB and the results obtained are compared with the results obtained through the dual optimization algorithm to check the performance of the relaxation technique. Minimum up time, down time constraints and startup costs are considered in this case study. Ramp rate constraints and reserve capacity constraints are ignored and shut down cost is taken as zero.