Design and Experimental Investigation of 500kV Current Transformer Seismic Retrofit Utilizing Structure Rocking and Supplemental Damping with Self-Centering.

摘要

Electrical substations perform a key role in electrical transmission and distribution; the ability for a substation to remain functional during and after a seismic event contributes significantly to the resilience of the clients supplied. Many legacy components currently installed in the main grid substations were designed with minimal consideration of lateral loads and are not qualified per IEEE693. One of the more critical high-voltage substation components that are vulnerable to earthquake damage is the 500kV freestanding current transformer (CT). The CT is particularly vulnerable due to the slenderness and mass distribution of the component. Current transformers are typically constructed from a combination of aluminum and brittle porcelain. Two novel retrofit measures were investigated utilizing base rocking and supplemental damping to reduce the seismic amplification in the CT while also potentially providing post-earthquake self-centering capability. The retrofit measures utilize both shift in system frequency and energy dissipation through supplemental damping to reduce seismic demands on the CT. The purpose of the research was to conceptually develop, detail design, analyze and experimentally validate the retrofit measures. A desired feature of the retrofit measures was for minimal or no residual displacement following the seismic event, which was implemented in the retrofit through a preloaded centering mechanism. Based on the analyses and experiments, the proposed retrofit measures exhibited significantly decreased demands on the CT and true self-centering.