Fuzzy logic approach for generation dispatch of electric power system with conflicting objectives

An interactive fuzzy satisfying method is presented for solving multiobjective thermal power dispatch problem by assuming that the decision maker (DM) has fuzzy goals for each of the objective function. A multiobjective thermal power dispatch problem minimizes number of objectives viz operating cost, gaseous emission and security etc. together while allocating the electricity demand among the committed generating units subject to physical and technological constraints. Generally, multiobjective problems are solved to generate noninferior solutions using weighting method. Afterwards the DM is provided with a set of simple but effective tools to choose the best alternative among noninferior solutions. The generation of noninferior solution requires enormous amount of computation time when the objectives are more than two. In this paper, weighting method is used to generate noninferior solutions for DM in which the problem is solved many times for different set of weights. The 'best' compromised solution has been obtained by searching for optimal weight pattern using simplex search method. Fuzzy set theory has been exploited to decide the 'preferred' optimal operating point. The noninferior solution that attains maximum satisfaction level from the membership functions of the participating objectives has been adjudged the 'best' solution. The proposed method circumvents the exhaustive evaluation of complete noninferior surface needed. The validity of the proposed method has been demonstrated on an 11 nodes sample system comprising five generators.