Multicriteria Load Dispatch with Fuzzy Constraints

The fuzzy linear programming method for solving optimization problems containing several objective functions is briefly discussed and adapted to deal with the various cases of fuzzy constraints. For each type of fuzzy constraints, proper piecewise linear membership functions are suggested, where some of them are decomposed into new simpler types in a manner to fit the method of solution based on the method used in Zimmerman 1978 and extended in Yang et al., 1991. Thus, a fuzzy environment is prepared to solve successfully the multicriteria load dispatch problem in power systems, viewed more realistically to contain some flexible or fuzzy operational constraints. A program is developed to test this algorithm applied to an economic-environmental load dispatch problem on a sample power system, where the total production cost and the total produced emission are to be minimized. The results of various cases of fuzzy and crisp modes of the load and the generation range of the units are analyzed in the case study. It will be seen that the method also can be applied efficiently when priorities are assigned to the objective functions.