A novel approach for short-term hydrothermal scheduling using hybrid technique

The short-term hydrothermal co-ordination of power system, which is a large scale, combinatorial and nonlinear optimization problem has been extensively studied because of its significant economical impact. In this paper an effective short-term hydrothermal scheduling algorithm based on a hybrid evolutionary and a conventional technique is proposed. In the algorithm the thermal units on the system are represented by an equivalent unit. The power balance constraints, total water discharge constraints, reservoir volume constraints and constraints on operating limits of the equivalent thermal and hydro units are taken into account. The proposed method is developed in such a way that a standard adaptive evolutionary programming method is acting as a base level search and it directs the search towards the optimum region. Thereafter local optimization by direct search and systematic reduction in size of search region method is next employed to do fine tuning. The algorithm is demonstrated through an example of standard test system with a hydro plant and an equivalent thermal plant for a time schedule of six 12-hour intervals. The results are examined to validate the effectiveness of the algorithm