The Power Transformer Condition Monitoring System Based On Vibration Method

It is very important for the power transformer's normal operation, so monitoring the state of a running power transformer at real-time is quite significative. There are two main kinds of method testing the power transformers. One is Off-Service detection, and the other is In-Service monitoring. Because In-Service monitoring needn't to stop transformers from working, it tests much more conveniently and exactly. Just taking the electric characteristics into account but ignoring the mechanical characteristics is the shortcomings of the old In-Service monitoring system, which should be improved. The vibration signals of oil-tank's surface can reflect the states of running power transformer's windings and cores, so it is a quite useful method on transformer's In-Service monitoring.The objective of this paper is to design and develop a measurement system based on vibration method, it can be used for condition monitoring of power transformers (TCMS) in fieldwork. TCMS has been supported by a grant from Ningbo. In the beginning of the paper, TCMS was introduced in detail, including structure, hardware design, outer interface, sensor fixing and so on, especially some measures to restrain interference in hardware design. Next, as main work undertaken by writer, the paper introduced the front-end computer used for data sampling, including designing software, communication protocol, basic software functions as well as software architecture. In the end, because Fourier analytical method has lots of disadvantages of processing non-linear signals, a new method called Hilbert-Huang Transform (HHT) was used to process vibration signals sampling from a power transform in Ningbo. By time-frequency-energy three-dimensional plot, we got some vibration signals' intrinsical characteristics on oil-tank's surface, such as fundamental frequency and harmonics characteristic, energy density and so on. At last, we gave the reason why vibration's fundamental frequency is 100Hz and the reason inducing harmonics.Power transformers' modeling and fault diagnosing are emphesis in the future.