A Unified Energy Flow Analysis in Integrated Electricity and Natural Gas Systems Considering State Variables of Energy Hub

With the integration of multiple energy conversion units into the integrated electricity and natural gas systems (IEGS), the analysis and calculation of energy flow becomes more complex. Furthermore, the state variables of multiple energy conversion units are needed to detailed model in the energy flow algorithm process. To cope with that, a unified energy flow algorithm is proposed in this paper, considering the influence of coupled units on energy flow calculation in IEGS. Firstly, the multi-energy conversion units are abstracted as a energy hub (EH), which provides a unified modeling method to describe the energy flow relationship between different energy networks. Secondly, the electric and gas inputs of EH are added to form a new state variable column vector based the original sub-network state variables. Then, a new Jacobian matrix is derived based on Newton-Raphson method to form an iterative relationship. Finally, case study is verified on the modified IEEE39-NGS20 test system. The proposed energy flow algorithm can effectively reduce computational burden in multi-energy networks.