A Systematic Method for Power System Hardening to Increase Resilience Against Earthquakes

Abstract

Although natural disasters have recently imposed enormous damages to power system infrastructures, resilience enhancement through hardening measures is not usually compensated in conventional power system planning. In this article, a framework is proposed to enhance the resilience of distribution systems against earthquakes. In particular, it focuses on substations’ retrofit whose failure can affect the distribution system, imposing outages to the customers connected to it. A knapsack based heuristic method, which considers the bus configuration of substation is proposed to select the substation components for hardening. The potential failure of substation components that would lead to complete unavailability of substation is evaluated through minimal cut set-fault tree analysis. A criterion for resilience enhancement is proposed, including hardening cost, cost incurred by damaged components, cost of customers’ interruption in the distribution system level, and power generation cost of Distributed Energy Resources. A penalty mechanism taking into account the component repair time is used to estimate interruption costs. The impact of earthquakes on substation components is modeled using fragility curves. A case study with real earthquake characteristics is considered and Monte Carlo simulation is used to capture the stochastic failure of substation components. The results show that power transformers and circuit breakers at 20 kV are the most critical components in the retrofitting strategies.