An Interactive Fuzzy Satisficing Method for Multiobjective Operation Planning of District Heating and Cooling Plants Considering Various Penalties for Violation of Contract

District heating and cooling (DHC) systems have been actively introduced as energy supply systems in urban areas. Since there exist a number of large-size freezers, heat exchangers and boilers in a DHC plant to generate and supply cold water, hot water and steam to a DHC system, the control under an operation plan for these instruments on the basis of the demand of cold water, hot water and steam, called heat load, is important for stable and economical management of DHC systems. In this paper, we formulate an operation planning problem of an actual DHC plant as a nonlinear integer programming problem in consideration of various penalties for violation of contracts. Furthermore, in order to reflect actual decision making situations for DHC plants more appropriately, we formulate a multiobjective operation planning problem to minimize not only the running cost but the amount of primary energy consumption from the viewpoint of saving energy. Then, we propose an interactive fuzzy satisficing method through tabu search for multiobjective operation planning problems to derive a satisficing solution for the decision maker.