Towards Fast and Robust Simulation in Integrated Electricity and Gas System: A Sequential United Method

The decoupling method, in which different energy vectors are solved alternatively, is widely adopted in the integrated electricity and gas systems (IEGS) analysis. Nevertheless, the bidirectional interaction created by power to gas (P2G) and gas turbines (GT) requires iterative calculations between the electric power system (EPS) and the natural gas network (NGN). Without proper solutions, the iterations will raise predictable concerns about simulation efficiency and convergence. Therefore, this paper investigates the fast and robust simulation in IEGS considering the nonlinearity and dynamics from both the network and device sides. To address the bidirectional interaction, a state decoupling method (SDM) is first proposed as an efficient solver for the dynamic NGN model. Based on this, a sequential united method (SUM) is developed to reduce the computational cost and improve the solver robustness, which decouples the large-scale Jacobian matrix inversion into the sequential solution of multiple small sub-matrixes. Case studies in two systems demonstrate the superiority of the proposed method compared with the decoupling method, indicating a significant improvement of SUM in simulation efficiency and robustness.