基于振动非线性特征的变压器绕组状态检测

Transformer winding condition detection based onthe nonlinear characteristics of vibrations

电力变压器是电网系统中的关键设备,绕组又是变压器的核心部件。为了对带电绕组进行状态检测,文中根据绕组结构参数随负载变化的关系,建立振动幅值与电流之间的非线性模型,证明了结构刚度与模型参数的数值关系,并提出基于振动非线性特征的绕组压紧力评价方法。实验中,在调整绕组轴向压紧力的同时进行短路负载实验,获取电流与振动幅值的关系,结果表明,在绕组压紧力较小的情况下,振动的非线性特征较显著,且特征参数C 3准确反映了绕组结构等效刚度的变化。在实际应用中,比较正常绕组和松动绕组对应的油箱表面振动特征,并将结果以二维等高线的形式呈现,结果表明,油箱表面振动特征体现了测点附近绕组的结构状态。上述结果证明特征参数C 3是压紧力的单调函数,当该数值大于0.5时绕组存在结构状态劣化。

Power transformers are critical devices in power grid systems,with windings as their core components.To perform state detection on online windings,this paper establishes a nonlinear model between vibration amplitude and current based on the relationship between winding structural parameters and load variations.The numerical relationship between structural stiffness and model parameters is proved,and a winding clamping force evaluation method based on the nonlinear characteristics of vibrations is proposed.In the experiment,the relationship between current and vibration amplitude is obtained by adjusting the axial clamping force of windings and performing short-circuit load tests.The experimental results show that the nonlinear characteristics of vibrations are significant when the winding clamping force is small,and the characteristic parameter C 3 accurately reflects the equivalent stiffness change of the winding structure.In practical applications,the vibration characteristics of oil tank surface corresponding to normal windings and loose windings are compared,and the results are presented in the form of two-dimensional contour plot.The results indicate that the vibration characteristics of the tank reflect the structural state of the winding near the measurement point.The above results demonstrate that the parameter C 3 is a monotonic function of clamping force,and there is structural degradation in the winding when this value is greater than 0.5.