Structural Resilience of Pole-Mounted Substations Subjected to Flooding: Generalized Framework and a Malaysian Case Study

Abstract

Substations are vital components of electricity supply, representing a weak point in a power network due to their vulnerability to flood events. Pole-mounted substations can effectively mitigate inundation failures by elevating electrical equipment. However, the supporting structures of such substations often are not designed to withstand flood flows, and thus are prone to structural failure. This paper proposes a generalized framework to quantify the structural failure probabilities of pole-mounted substations and to assess their structural resilience to flooding. The generalized framework was applied to a case-study location in Malaysia, where serious flood events are common and pole-mounted substations abound. The study first identifies and quantifies the flood effects on the poles, including pure hydrodynamic forces, the impact of floating debris, debris damming effects, and scouring. The quantified flood effects then are compared with the structural capacity of a typical pole-mounted substation structure and its foundation, to derive a capacity threshold curve for structural failure. The failure probability is illustrated via fragility curves for different flood depths and risk curves for different flood and wind return periods, to assess further the substation’s structural resilience. The aforementioned curves are based on a stochastic distribution of flood depths and velocities represented by a normalized Weibull function. This approach can be adapted easily to depict flood conditions for any given location. Overall, the results of this paper can help stakeholders, including those designing and managing substation structures, to quantify, assess, and further enhance the flood resilience of power-supply networks.