Vibration Analysis Method of Windings for Transformer Condition Monitoring

Despite techniques such as Dissolved Gas Analysis (DGA) and Sweep Frequency Response Analysis (SFRA) being widely used in transformer maintenance, winding vibration characteristics are able to provide information about mechanical conditions through the winding's natural frequencies and mode shapes. In this paper, a combination of discrete and continuous models is proposed in order to identify and understand the dynamic behaviour of disk-type winding of power transformers. First, three slightly different multi-degree of freedom (MDOF) mass-spring-damper systems are used to obtain the eigenvalues and eigenvectors of axial, flexural, and torsional vibrations. In the second approach, in-plane and out-of-plane vibrations of windings are described by coupled-ring models. Different failure scenarios are simulated with the proposed models and compared with numerical models validated in previous works performed with a 10 kV single-phase transformer. The outcome of this work is a set of models that when combined allow a complete and efficient definition of the windings' mode shapes, an important key for noise control and identification of faults in power transformers.