To evaluate the earthquake-resistance capability of an entire substation, which is a complex multi-input-multi-output system (MIMOS) composed of many various types of electrical equipment interconnected by conductors, a flow-based analysis model integrating the merit of the flow block diagram and state tree method was introduced. Two performance indicators of a substation were defined from different stakeholders, one is the expected total power transmission capacity and the other is the power accessibility to the targeted users from the substation. And directed graph logic system analysis models were developed on the Simulink platform based on the original internal logic relationship among distributed components and the power delivery path in the substation with different function types. Afterward, the defined reliability indicators associated with the overall system under a certain seismic intensity level can be obtained by combining the seismic vulnerability curve at the equipment level through the Monte Carlo simulation method. The feasibility and accuracy of the proposed system vulnerability analysis model were verified by comparison with the analytical solution through the illustrative simple MIMOS. Then A case study on a practical 220/110 kV substation was conducted, the analysis results can assist decision-makers in seismic optimization of different retrofitting measures and distribution plans for substations.

Electrical substations are crucial components in a power system while substation equipment can be easily damaged in an earthquake. Repairing the damaged equipment as soon as possible is essential to restore the functionality of the substation system and further secure the sustainable power supply of the power grid after the earthquake. However, the damaged equipment cannot be repaired simultaneously due to the limitation of emergency repair resources, and the recovery rate of the substation functionality will vary dramatically depending on the selection of different equipment repair sequences. Therefore, a sensible equipment repair sequence is needed to improve the recovery efficiency of the substation functionality. A resilience-based method was thus proposed in this paper to optimize the equipment repair sequence with the objective of minimizing the resilience index of the substation, which was defined as the post-earthquake overall functionality loss. The heuristic algorithm was incorporated into the systemic resilience assessment framework to find the optimal equipment repair sequence according to different initial damage states of equipment and the limitation of emergency repair resources. A case study was performed on a real-world substation system to illustrate and verify the proposed method, the analysis results can aid decision-makers in the post-earthquake recovery planning.