A comprehensive model for self-scheduling an energy hub to supply cooling, heating and electrical demands of a building

This paper presents an innovative method for modeling energy hubs based on energy flow between its constituent elements. Using this method, modeling of energy hubs with different elements and connections is facilitated. Also, an appropriate mixed integer nonlinear programming model is presented for short term 24-hour scheduling an energy hub, in which, the objective is to fulfill daily cooling, heating and electric demands of a hypothetical building with the maximum profit. Furthermore, in the energy flow based modeling method presented in this paper, energy storage elements are not only used at the output of the hub; but also, are capable of being used as inputs for other elements inside the energy hub. In order to evaluate the performance of the model, simulations have been accomplished for one hot and one cold typical day. Presented energy hub includes various elements such as combined heat and power, electric heat pump, boiler, absorption chiller and electrical and thermal energy storages. Moreover, in the modeling of the proposed energy hub, feasible operation region for combined heat and power system together with technical constraints of energy hub equipment is considered. Analyzing numerical results, flexibility of the energy hub for feeding the required loads of the building, operation of combined heat and power and the effect of electrical heat pumps in meeting cooling and heating loads of the building are evaluated. The numerical results show that combined heat and power operation points and its average electrical and thermal efficiency in hot and cold days are totally different and electric heat pump, regarding its high efficiency, is the main supplier of cooling and heating loads of the building in the studied energy hub.