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Seismic performance and stiffening strategy of transformer bushings on sidewall cover plates
Abstract Transformer bushings are vulnerable to ground motions during earthquakes due to the amplification by the cover plates of the transformer tank. In addition, the stiffening strategies and the seismic performance of sidewall bushings with L-shaped turrets are under-investigated. In this study, a full-scale transformer tank with top and sidewall bushing was tested, with and without stiffening using steel diagonal braces. In addition, a numerical model of the transformer-bushing system is established by idealizing the flexibility of the cover plate as rotational springs. The test results show that the flexibility of the sidewall cover plate contributes to the vulnerability of the bushing, and the sidewall bushing is more vulnerable than the top bushing. The motion at the top of bushings primarily contributes from the bending of the cover plates, while the sidewall cover plate needs sufficiently stiff stiffeners. The diagonal braces effectively reduce the stress and displacement responses of the sidewall bushing by constraining the rocking motion of the turret and increasing the damping ratio. However, the use of these diagonal braces can generate problems if the natural frequency of the tank is close to that of the bushing. Therefore, the transformer tank should be considered in the design of stiffening strategy. However, the diagonal braces are recommended for use when the natural frequency of the transformer tank is much larger than that of the bushing.
Graphical abstract Display Omitted
Highlights The influence of the sidewall cover plate and turret on the seismic performance of the sidewall bushing is investigated. Stiffening strategy using braces to reduce the stress of bushings and the out-of-plane deformation of plates is proposed. The effectiveness of the diagonal braces is analyzed numerically and then validated experimentally. The influence of the transformer tank on the effectiveness of the diagonal steel braces is discussed.
Seismic performance and stiffening strategy of transformer bushings on sidewall cover plates
Abstract Transformer bushings are vulnerable to ground motions during earthquakes due to the amplification by the cover plates of the transformer tank. In addition, the stiffening strategies and the seismic performance of sidewall bushings with L-shaped turrets are under-investigated. In this study, a full-scale transformer tank with top and sidewall bushing was tested, with and without stiffening using steel diagonal braces. In addition, a numerical model of the transformer-bushing system is established by idealizing the flexibility of the cover plate as rotational springs. The test results show that the flexibility of the sidewall cover plate contributes to the vulnerability of the bushing, and the sidewall bushing is more vulnerable than the top bushing. The motion at the top of bushings primarily contributes from the bending of the cover plates, while the sidewall cover plate needs sufficiently stiff stiffeners. The diagonal braces effectively reduce the stress and displacement responses of the sidewall bushing by constraining the rocking motion of the turret and increasing the damping ratio. However, the use of these diagonal braces can generate problems if the natural frequency of the tank is close to that of the bushing. Therefore, the transformer tank should be considered in the design of stiffening strategy. However, the diagonal braces are recommended for use when the natural frequency of the transformer tank is much larger than that of the bushing.
Graphical abstract Display Omitted
Highlights The influence of the sidewall cover plate and turret on the seismic performance of the sidewall bushing is investigated. Stiffening strategy using braces to reduce the stress of bushings and the out-of-plane deformation of plates is proposed. The effectiveness of the diagonal braces is analyzed numerically and then validated experimentally. The influence of the transformer tank on the effectiveness of the diagonal steel braces is discussed.
Seismic performance and stiffening strategy of transformer bushings on sidewall cover plates
Yang, Zhenyu (author) / He, Chang (author) / Xie, Qiang (author)
2020-07-23
Article (Journal)
Electronic Resource
English
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