基于振动的变压器绕组压紧状态评估方法

为实时评估变压器绕组压紧状态,对变压器振动问题进行研究。在绕组振动成分、振动传播路径和油箱表面振动成分的研究基础上,建立了变压器油箱振动信号模型。在瞬态激振实验中发现:相对于油箱正面测点,顶面测点更能体现油箱瞬态激振响应逐渐衰减的特征;靠近C相套管的顶面测点共振频段随压紧力减小而明显向左位移。进行短路实验,结合不同电流不同压紧状态下的大量实验数据,发现靠近C相套管的顶面测点振动信号共振谱峰分布与瞬态激振实验中共振频段分布较为一致,提出利用共振谱峰位移规律进行绕组压紧状态在线评估。该方法简单易行,只需监测油箱顶面振动信号,适应变压器负荷变化的运行环境,与电网没有电气连接,可以实现变压器绕组压紧状态在线评估。

Evaluation Method for Transformer Windings Pressed State Based on Vibration

Research is made on the transformer vibration problem for real-time evaluation of transformer winding pressed state. A transformer tank vibration signal model is developed based on a study of the components of winding vibration, vibration transmission path and components of the tank surface vibration. It is found from transient excitation experiments that, relative to the front tank measuring points, the measuring points on the top surface reflect damping characteristics of the tank vibration better; the resonance frequency band of measuring point on the top surface and near the phase C casing is shifted to the left with the pressed force reduced. In the short-circuit experiments, by referring to a large number of experimental data in different current and pressed states, it is found that the distribution of resonance peaks of the measuring points on the top surface and near the phase C casing is consistent with the distribution of the resonance frequency band of measuring points on the top surface in the transient excitation experiments. The law of resonance spectra peak displacement is proposed for use in online evaluation of the transformer winding pressed state. The method is simple in which only the tank top surface vibration signal should be monitored. This method is adapted to the changing operating environment of the transformer with no electrical connection to the grid. Online evaluation of the transformer winding pressed state can be achieved. This work is supported by 2014 Key Scientific and Technological Projects of State Grid Jiangsu Electric Power Company (No. J2014055).