Unified calculation of multi-energy flow for integrated energy system based on difference grid

The comprehensive utilization of electricity, gas, and heat energy is an important way of energy transformation. However, different energy forms follow different physical laws, which brings great challenges to the collaborative analysis and optimization of the integrated energy system (IES). In this paper, a unified time-domain model of IES is developed based on the two-port network equivalence theory. First, the unified linear equations for IES are derived according to the basic dynamic models of electricity, gas, and heat networks. Second, a unified model of the multi-energy branch based on the finite difference scheme is proposed. The complex internal information of the branch is transformed into equivalent transfer matrixes of initial and boundary conditions. Finally, combined with the network topological equations, a multi-energy flow calculation model is established. Numerical simulation results show that the proposed modeling method has higher computational efficiency than the traditional finite difference method.