Seismic vulnerability assessment of power grid systems

Electric power systems play a critical role in assuring modern society’s functionalities. Earthquakes are one of the most destructive natural hazards that affect the serviceability of electricity transmission systems. The earthquake excitations applied to each component of a power grid system (e.g., plants, substations and transmission lines) are spatially correlated by nature due to common causes. Yet limited attention has been paid to the impact of this spatial correlation on power grid system vulnerability. This paper presents an approach for estimating the seismic vulnerability of power grid systems using the network flow theory to model the power flow allocation over the grid components. A stochastic ground motion model is employed to represent the spatial characteristics of earthquake excitations. The proposed method is illustrated through an application to the seismic vulnerability assessment of the national power grid of Italy. The overall vulnerability is measured and evaluated through a proposed metric, and the critical components of the grid system are identified. The impact of spatial correlation of earthquake ground motion on the grid system vulnerability is also investigated.