Integrated power-gas systems (IPGS) have developed critical infrastructure in integrated energy systems. Moreover, various extreme weather events with low probability and high risk have seriously affected the stable operation of IPGSs. Due to close interconnectedness through coupling elements between the power system (PS) and natural gas system (NGS) when a disturbance happens in one system, a series of complicated sequences of dependent events may follow in another system. Especially under extreme conditions, this coupling can lead to a dramatic degradation of system performance, resulting in catastrophic failures. Therefore, there is an urgent need to model and evaluate resilience of IPGSs under extreme weather. Following this development trend, an integrated model for resilience evaluation of IPGS is proposed under extreme weather events focusing on windstorms. First, a framework of IPGS is proposed to describe states of the system at different stages under disaster conditions. Furthermore, an evaluation model considering cascading effects is used to quantify the impact of windstorms on NGS and PS. Meanwhile, a Monte Carlo simulation (MCS) technique is utilized to characterize chaotic fault of components. Moreover, time-dependent nodal and system resilience indices for IPGS are proposed to display impacts of windstorms. Numerical results on the IPGS test system demonstrate the proposed methods.

Integrated power-gas systems (IPGSs) make the power system and natural gas system (NGS) as a whole, and strengthen interdependence between the two systems. Due to bi-directional energy conversion in IPGS, a disturbance may turn into a catastrophic outage. Meanwhile, increasing proportion of renewable energy brings challenges to reliability of IPGS. Moreover, partial failure or degradation of system performance leads IPGS operate at multiple performance levels. Therefore, this paper proposes a reliability assessment model of IPGSs which represents multiple performance of components and considers cascading effects, as well as renewable energy uncertainty. First, a framework of IPGS reliability assessment is proposed: multi-state models for main elements in the IPGS are represented. Especially a gas-power-generation calculation operator and a power-to-gas calculation operator are utilized to bi-directionally convert a multi-state model between NGS and power systems. Furthermore, nodal reliability indices for IPGS are given to display impacts of cascading effects and renewable energy uncertainty on reliabilities of IPGSs. Numerical results on IPGS test system demonstrate the proposed methods.