School of Electric and Electronic Engineering, North China Electric Power University, Baoding 071003, China

While the coupling relationship between the power grid and the natural gas network tends to be close, fault propagation across heterogeneous energy systems introduces new risks of cascading failures in the gas-electricity interconnected system. However, none of the related studies conducted at the current stage has taken into account the characteristics of gas temperature change during the transmission process of natural gas, which may make it difficult to reflect the actual evolution of cascading failures and conduct an accurate impact assessment. Firstly, this paper deduces the non-isothermal transport equation in the steady state of a natural gas pipeline and establishes the corresponding model. Through theoretical analysis and simulation, it is proven that there is a relationship among the gas flow rate, gas temperature, and pressure difference between the beginning and end of the pipeline. On this basis, a model for evaluating the cascading failures of gas-electricity interconnected system considering the non-isothermal characteristics of natural gas is proposed to more accurately assess the impact of natural gas on the cascading failures. Finally, the validity of the proposed model is verified with a test case consisting of an IEEE 39-bus system and a modified Belgian 20-bus natural gas system, and compared and analyzed with related studies based on the isothermal assumption. The results show that the proposed model can adequately reflect the non-isothermal characteristic of the natural gas system, with regard to its accuracy and practicality in assessing the impacts of cascading failures in the power system.