Resilience enhancement of island integrated energy systems under seismic hazards: A two-stage restoration strategy

Seismic hazards are sudden and destructive events that can cause failures in the electricity, natural gas, and heating subsystems of island integrated energy systems (IIES). Such failures severely hinder the stable supply of energy to critical loads and pose threats to island energy security. However, quantitative assessments of the impacts of seismic hazards on the energy supply capability of IIES remain limited, thus strategies for improving system resilience require further development. To address these issues, this study proposes a resilience enhancement strategy guided by energy supply satisfaction. First, models of the IIES and seismic hazards are established to quantify the failure probabilities of electricity, gas, and heat supply paths under seismic impacts. Second, a resilience evaluation framework is developed by introducing differentiated load weights to reflect the supply priority of critical loads. On this basis, a two-stage strategy combining pre-disaster reinforcement and post-disaster response is designed. Through topology reconfiguration and multi-energy coordination, the complementary characteristics of electricity, natural gas, and heating are utilized to enhance system resilience. Case studies on the E33–G14–H7 test system show that, compared with the post-disaster coordination-only scheme with an energy supply satisfaction of 0.69, the proposed strategy increases energy supply satisfaction by 0.24 to 0.93 and achieves a critical load restoration ratio of 95.62%, verifying its effectiveness under seismic conditions.