Unified modeling of regionally integrated energy system and application to optimization

Regionally Integrated Energy System (RIES) combines electricity, heat, natural gas, and other energy sources to improve the overall utilization efficiency of the energy system as well as to satisfy the energy demand. However, the energy flows relationship in RIES is highly interconnected because of the energy network's topology complexity and other energy factors, creating challenges in optimizing the system operation. This paper proposes a unified modeling method by incorporating an energy hub (EH) to integrate various components and energy flow relationships in RIES. The RIES energy network equations are built in the matrix forms to describe the energy conversion and coupling via energy flow selection as state variable and branches/nodes definition based on network graph theory. Based on the energy network equations, the optimized operation model is proposed in unified form as the optimal operation of RIES that reduce the complexity of optimal operation compared with the traditional nonlinear model. Finally, a test system is presented to demonstrate the optimal operation model, compared and analyzed the optimized results between unified modeling and traditional nonlinear modeling to prove the effectiveness of the modeling method. The results show both optimality of the cost and computing time have been improved by the unified modeling method.