基于振动信号的变压器绕组松动故障诊断方法

提出了基于运行中变压器表面振动信号的绕组松动故障诊断模型和诊断方法。首先,分析了绕组振动幅值与电流、预紧力、铁芯振动、非线性因素的关系,确定振动信号中100 Hz为绕组松动的特征频率,提出分离绕组振动幅值和铁芯振动幅值的方法;提出绕组松动诊断模型和基于该模型的平均安全余量,利用待检测变压器在一组负载电流下的绕组振幅计算平均安全余量,由此定量判断绕组的松动状态。利用有限元仿真和现场实验分别对诊断模型和诊断方法进行检验,实验结果显示平均安全余量在1±0.5之外时存在松动故障,值越远离1,松动程度越大。该方法解决了变压器实际运行中绕组和铁芯振动基频相同、矢量叠加相互影响的问题及实际运行中负载变化,电流不同,仅用某个电流下的振幅判断精度受限的问题,且对松动程度量化表示,易于判断。

Vibration Signal Based Diagnosis Method for Looseness Fault of Transformer Winding

A diagnosis model and a diagnosis method for looseness fault of transformer winding are proposed based on the surface vibration signal of the transformer in operation. Firstly, the relationship between the amplitude of the winding vibration and the current, the preload, the vibration of the iron core and the nonlinear factor is analyzed. And the characteristic frequency of the 100 Hz is determined. Then the method for separating winding vibration amplitude and vibration amplitude of iron core is proposed. A diagnosis model of winding and the average safety allowance based on the model are proposed. The average safety allowance is calculated using the amplitude of the windings detected in a set of load current to determine the state of the winding. Finite element simulation and experiment are used to test the diagnosis model and method. Experimental results show there is a loosening fault when the average safety allowance is beyond the range. The farther away the allowance is from 1, the greater the degree of loosening. The method solves two problems of the transformer in operation: the problem of the transformer at the same fundamental frequency and vector superposition of the winding and the iron core''s vibration in actual operation; the load and the current changes, the problem of accuracy being limited is judged only by the amplitude of a current, which is easy to do thanks to quantification of the degree of looseness.