COMPARATIVE STUDY OF DIFFERENT FORMULATIONS IN HYDRO-THERMAL OPTIMAL LOAD FLOW PROBLEM

Abstract This paper deals with the optimal power flow problem in a fixed-head hydrothermal electric power system. As the hydro generation is energy limited, a dynamic optimization problem involving the daily scheduling of the system is encountered. This dynamic optimal power flow problem requires a solution of a large scale set of non-linear simultaneous equations. Newton-Raphson's method has been implemented to obtain the optimal operational strategy. Due to the large scale nature of the problem, we have adopted a sparse matrix solution to the problem. Three different formulations involving (1) Polar form (2) Rectangular form and (3) Current mismatch form have been developed. We have developed an algorithm with three different versions. Implementation of these methods is detailed in this paper. The algorithms have been successfully executed for six different IEEE test systems varying in size from 5-bus to 118-bus systems. The test results and CPU times are detailed. A comparative study of the performance...