An enhanced reliability assessment method for integrated energy system during seismic hazards: Using iterative algorithm and impact-increment enumeration method

• Establish a probability model for transmission line failure during seismic hazards considering the influence of multiple factors. • Build a probability model for transmission line failures in earthquakes, factoring in multiple influences. • Develop a prob. model for line failure in earthquakes, factoring in multiple influences. This paper presents a novel reliability assessment framework specifically designed to accurately evaluate the reliability of integrated energy systems (IES) during seismic hazards. The proposed framework primarily comprises four key components an optimal model that integrally accounts for renewable energy accommodation and power load supply a methodology for calculating transmission line failure probabilities the ULCI-IISE (Impact Increment State Enumeration based on Upper-Cut sets and Lower-Complement sets) and a technique for generating typical operating scenarios. The ULCI-IISE method innovatively integrates the Impact Increment State Enumeration (IISE) with iterative calculation of upper cut sets and lower complement sets, while leveraging the sparsity characteristic of failure probabilities under seismic events to improve computational efficiency. To address the uncertainty of renewable energy, the framework employs Third-order Polynomial Normal Transformation (TPNT) to generate spatiotemporally correlated scenarios for renewable energy units, and utilizes ordinal clustering to characterize typical electric load scenarios. Additionally, the clustering method is further applied to effectively reduce the number of calculating scenarios. Furthermore, the failure probability of transmission lines during seismic hazards is quantified through a decomposition into influential factors. The proposed framework demonstrates the capability to rapidly and accurately assess IES reliability. Its validity is rigorously validated through a case study conducted on a practical 500 kV power system.