Load scheduling of hydroelectric/thermal generating systems using nonlinear programming techniques

The load scheduling problem of hydroelectric/thermal systems can be split into long-range and short-range problems. The short-range problem is to allocate the hydroelectric energy available at each station over the period of day, so as to meet the load demand and minimise the overall cost of thermal generation. If the head variations in reservoirs are neglected and if the period is discretised, the problem can be posed as a nonlinear-programming problem of a special kind in terms of the busbar-voltage variables. An algorithm which splits the problem into smaller-dimension problems is described. It is particularly suitable for large systems, in view of the storage requirements of the digital computer. An example, consisting of two hydroelectric stations, three thermal stations and two load stations is solved, and the results are presented.