This paper reports the development of a two-level optimization methodology to help design a tri-generation system for a given district which satisfies the heating, cooling, and hot water demands and at the same time, minimize the annual total costs and CO₂ emissions. An optimization methodology is proposed and tested on a virtual district with eight buildings where three of them can host the district technologies including heat pump, gas engine, and lake cooling. Within the building, some backup technologies may be implemented including an air/water heat pump, a water/water heat pump, a boiler, and electric chillers. Analysis of the Pareto optimal frontier results in several distinct groups of configuration based on the selected district conversion technologies and their capacities. Solution to the sub-problems including design and operation of the district energy system is carried out by applying a Mixed Integer Programming (MIP) technique. Several different clusters are defined and studied regarding the cost and CO₂ emission. A reference configuration is defined for the purpose of comparison in which electricity is supplied by the grid, heating and hot water by a boiler, and cooling by an electric chiller. Compared to this configuration, the best solution with respect to CO₂ emissions causes 59% emission and 75% cost of the reference configuration. In this case, 53% of the total cost is associated with the initial investment cost while the rest 47% is associated with the operational cost. The optimal configuration with respect to the annual costs causes 86% more emission than the reference configuration and 38% less annual costs. In this case, 22% of the total cost is associated with initial investment cost while 78% of the total cost is associated with the operational cost. Implementation of a two-pipe system instead of a four-pipe system results in nearly 5% reduction in total annual cost.

中文翻译：

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区域能源系统同时设计和调度的两级多目标优化

本文报告了两级优化方法的发展，以帮助设计给定区域的三代系统，该系统既满足供热，制冷和热水需求，同时又将年度总成本和CO ₂降至最低排放。提出了一种优化方法，并在具有八座建筑物的虚拟区域中进行了测试，其中三座建筑物可以承载热泵，燃气发动机和湖泊冷却等区域技术。在建筑物内，可以实施一些备用技术，包括空气/水热泵，水/水热泵，锅炉和电冷却器。对帕累托最优边界的分析得出了基于所选区域转换技术及其能力的几种不同的配置组。子问题的解决方案包括区域能源系统的设计和运行，这是通过应用混合整数规划（MIP）技术进行的。关于成本和CO _2，定义和研究了几个不同的集群排放。为了比较的目的，定义了参考配置，在该参考配置中，由电网供电，由锅炉供热和热水，以及由电冷却器进行冷却。与该配置相比，CO ₂的最佳解决方案排放引起参考配置的59％排放和75％的成本。在这种情况下，总成本的53％与初始投资成本相关，而其余47％与运营成本相关。就年度成本而言，最佳配置导致的排放量比参考配置多86％，而使年度成本减少38％。在这种情况下，总成本的22％与初始投资成本相关，而总成本的78％与运营成本相关。采用两管系统而不是四管系统可导致年度总成本降低近5％。