考虑土-结构相互作用的特高压变压器抗震性能分析

Finite Element Analysis of Seismic Performance of Ultra High VoltageTransformer Based on Soil Structure Interaction

特高压变压器是变电站内重要的电气设施,进行变压器抗震计算时一般把地基基础考虑为绝对刚性,忽略了土体的影响。本文研究基于有限元数值仿真建立了土体-变压器的抗震分析模型,该模型考虑了土体在地震载荷下的非线性力学行为,并研究了变压器刚度及阻尼比变化对变压器抗震性能的影响。结果表明:数值模型与试验结果的频率误差在10%以内;在土体非线性力学行为影响下,随着地震峰值加速度的增加,特高压变压器的地震响应呈现出非线性增加的趋势;在0.2 g、0.4 g、0.8 g(g为重力加速度)地震激励下高压套管应力与试验误差分别为3.3%、2.6%、5.6%,说明了仿真分析力学模型的有效性。随着变压器刚度的增加,作为变压器薄弱环节的高压套管应力减小;阻尼比增加,设备的地震响应先增加后减小。研究成果可为特高压变压的抗震设计提供指导。

UHV(ultra high voltage)transformer is an important electrical facility in substation.In seismic calculation of transformer,the foundation is generally considered as rigid,and the influence of soil is ignored.To investigate the seismic performance of transformer considering soil-structure interaction,a seismic analysis model of soil-UHV transformer system was established based on finite element.The model considers the nonlinear mechanical behavior of soil under seismic load,and the effects of transformer stiffness and damping ratio change on the seismic performance of transformer were carried out.The results show that:the frequency error between the finite element numerical model and the test results is within 10%,and the stress and test error of high voltage bushing under 0.2 g,0.4 g and 0.8 g seismic excitation are 3.3%,2.6%and 5.6%respectively,which shows the effectiveness of the simulation analysis mechanical model.With the increase of transformer stiffness,as the weak link of transformer,the stress of high-voltage bushing decreases,the damping ratio increases,and the seismic response of equipment first increases and then decreases.The research results can provide guidance for the seismic design of UHV transformer.