Analysis of Multi-objective Optimal Dispatch of Cogeneration with Thermal Energy Storage for Building Energy Management System

Abstract

This paper presents analysis of the multi-objective optimal operation of designed BEMS which contains cogeneration or combined heat and power (CHP) and thermal energy storage (TES) as energy sources. The previously designed BEMS consists of CHP as the main energy supply with absorption chiller and auxiliary boiler. It is observed that there is excessive heat energy from CHP operation which is enough for further utilization. In this paper, TES is additional component to utilize excessive heat energy released from CHP operation. TES cooperates with CHP and auxiliary boiler to supply heat energy to meet the cooling load demand in the building. There are two objective functions for consideration, namely, total operating cost (TOC) and total carbon dioxide emission (TCOE). The multi-objective framework combines both objective functions and employs the weighted sum of TOC and TCOE. Furthermore, we vary initial state of TES from 0 - 20% of TES’s capacity and analyze its effect on TOC and TCOE. We apply the multi-objective approach to a large shopping mall. Numerical results show that setting initial state of TES to 0% can offer more reduction of TOC and TCOE than other initial conditions. The multi-objective optimal operation converges to minimum TOC when a weighting factor is 0. On the other hand, it converges to the minimum TCOE when the weighting factor is 1. In addition, the trade-off curve showing a relationship between TOC and TCOE provides operating points which depends on operator’s decision criterion.