Reliability Assessment for Integrated Power-gas Systems Considering Renewable Energy Uncertainty and Cascading Effects

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 bidirectional 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.