Study On Dielectric Response Measurement System Of Oil-Paper Insulation In Transformer

Power transformer is one of the most critical equipment in the power system, which is used to transform voltage, distribute and transport electricity, the reliability of power transforms guarantees its excellent operation. Now the numver of transformers grow fast than before, the power capacity increases continuous, and the voltage level improves too, so the security problem of transformer get more and more attention. So it is important for power system to detect the insulation condition of transformers and take fault diagnosis on it. It has important significance for the improvement of the reliability of power system.In this paper, a dielectric response measurement system of oil-paper insulation in transformer is designed, this system is based on frequency-domain spectroscopy and is used for field testing to analyse the insulation condition of transformer. The main research content and results are as follows.First, this paper studies the aging factors and detection methods of transformer oil-paper insulation. Then, the dielectric response methods based on time domain and frequency domain has been study, and the development status of this technology at domestic and international has been discussed too. Microscopic mechanism of the dielectric response is studied through the dielectric polarization and loss theory. To study the feasibility of frequency domain methods in the detection of transformer oil-paper insulation status, an extended Debye model of oil-paper insulation was established by MATLAB. The method for dielectric response testing and the calculation formula of Insulation information has been put forward.This paper designs the dielectric response test system based on the FDS methods, which has variable frequency drive signal source, response signal conditioning unit, data acquisition unit and the Upper Computer Software. The signal conditioning circuit is designed according to the characteristics of the dielectric response signals, which has advantages of weak signal processing, better antijamming performance and accuracy. The signal acquisition circuit is designed to convert the analog/digital signal by SCM.Upper Computer Software is designed by Virtual Instrument Technology.s. Communication module, signal analysis and processing modules, data computation module, data storage and query module are designed by Lab VIEW. And a convenient and intuitive system interface is designed based on the advantages of platform flexible and intuitive for Lab VIEW. The test system of dielectric response for the transformer oil-paper insulation designed by this paper is used to the transformers of Guangdong power grid Company Huizhou Power Supply Bureau. Two transformers’test date are selected to compare and analyse. The results and application show that the system designed by this paper is suitable for field testing of transformer oil-paper insulation condition with its advantages in convenience, efficiency and split hari accuracy.