پیاده سازی روش چند معیاره برای استراتژی عملیاتی سیستم های تولید همزمان تحت محدودیت های زیست محیطی

This paper presents a multi-objective approach based on evolutionary programming to solve the economical operation of cogeneration system under emission constraints. A multi-objective function including the minimization of cost and multi-emission is formulated in this paper. The cost model includes fuels cost and tie-line energy. The emissions with CO2, SOx, and NOx were derived as a function of fuel enthalpy. All constraints including fuel mix, operational constraints, and emission constraints must be met in the optimization process. The steam output, fuel mix, and power generations will be found by considering the time-of-use dispatch between cogeneration systems and utility companies. Data of an industrial cogeneration system was used to illustrate the effectiveness of the proposed method.

Cogeneration systems have now become an important power source to the industry. It offers a reliable, efficient, and an economic mean to supply both thermal and electrical energy. It can be constructed in urban areas and used as distributed electrical energy sources. Applications of cogeneration systems are still growing. More experience will be needed in improved operations for more energy saving. For effective operations, many strategies had been developed in [1], [2], [3], [4], [5] and [6]. Those strategies mainly dealt with the operating cost regardless of emissions constraints. The passage of the Clean Air Act Amendments of 1990 [7] has forced utilities to modify their operating strategies to meet environmental standards set by legislation. In recent years, some strategies including emission dispatching and fuel switching have been developed in [8], [9], [10], [11], [12] and [13]. These techniques intended to reduce both the emission and the operational cost. In addition, some multi-objective algorithms [14], [15] and [16] were successfully applied to solve bi-objective environmental/economic problem regarding minimization of operational cost and the total emission of NOx/SOx/CO2. The multi-emission, such as CO2, NOx, SOx, etc. are not all taken into account. In search procedure, it easily enables the decision makers (DMs) to alternative a paerto-optimal solution. DMs are not able to adjust single-emission dependent upon their importance.

A multi-objective function is formulated for the environmental/economic operation of cogeneration systems. The multi-objective approach with EP is used to solve the problem while meeting the requirements of steam capacity and electric power. This approach was tested on the system of a Petroleum Company. Results provide a practical and flexible framework for evaluating the multi-emission strategies. The search procedure provides an interactive mechanism for multi-fuel dispatch and operational cost. Simulations also proved that the TOU rate is significant in the overall economy of cogeneration systems. With the developed approach, DMs will know where to look for improvement and how to confirm a final schedule with the interactive procedure.