变压器油箱表面运行变形振型特性研究

The vibration on the oil-tank surface of transformer can reflect the mechanical condition of internal windings and cores, so that its vibration characteristics are very important for transformer fault diagnosis. The traditional single-point measurement method is affected by the inherent modal characteristics of the oil-tank, so that the vibration varies due to the location of the measuring point. And it changes with the fluctuation of loading, which limits the further application of this method. In this paper, the measurement method of operating deflection shapes (ODS) on the oil-tank surface was put forward. No-load tests and load tests were conducted on a single-phase transformer respectively. Shape correlation coefficient (SCC) was proposed to judge the deviation of ODS. At last, the ODS characteristics under winding looseness condition were studied. The experimental results show that in the stable working condition, the vibration acceleration of each measuring point is multiple frequencies composited, periodic steady and quasi-synchronous. On account of the accelerations having the same or opposite phase, the acceleration distribution is in the form of a wave shape, moreover, the positions with the maximum amplitude at different frequencies are different. The fluctuations of voltage and current only affect the amplitude, but do not affect the overall shape. The SCC is close to 1, that is, the vibration amplitude ratio between different points unchanged, the vibration phase unchanged. Compared with the normal case, the SCC of winding looseness is far less than 1, which indicated that the ODS changes obviously. These results can provide guidance for the diagnosis of transformer windings and cores.