Study On Nonlinear Isolation System Of Main Transformer Equipment Based On Metallic Rubber

The transformer substation,composed of a heavy and rigid box and several vulnerable porcelain bushings,generally presents mass and stiffness concentrating,high frequency and low damping ratio properties.Base isolation technology is a good choice for this kind of structures or instruments.The stiffness of most traditional isolation devices are usually seen as linear,and the isolators with nonlinear stiffness is seldom investigated.Therefore,based on the quasi zero stiffness of metallic rubber(MR)and the energy dissipation capacity of friction pendulum bearing,this paper presents a three-dimensional isolation bearing which can be applied to substation isolation.The specific research contents are as follows:(1)A novel type of isolation device was firstly proposed based on the strain hardening characteristics of metallic rubber materials.Then the effect of the parameters including loading frequencies,amplitude history as well as the diameter of steel wires on the mechanical performance of the isolator were investigated.In addition,the fatigue performance of the MR based isolator was studied.(2)Based on the mechanical test results and improved Bouc-Wen model,the constitutive model of the MR based isolator was proposed.Especially,the pinching function was adopted in the theory.Then,the corresponding parameters of the above mentioned model were identified.The isolation effect and displacement control effect of the new isolation system under the random earthquake excitation were analyzed later.(3)Based on a 1:5 scaled transformer substation model,shaking table test were carried out to verify the proposed nonlinear isolation theory,including the key influencing factors and their variation rules of the isolation effect of the device.This will provide theory,method and means for nonlinear isolation analysis,simulation and design of power facilities in substations under strong earthquake.