Transformer winding deformation diagnostic method based on discrete wavelet transform

Abstract

The invention provides a transformer winding deformation diagnostic method based on discrete wavelet transform. The transformer winding deformation diagnostic method is characterized in that the discrete wavelet transform method is applied to the frequency response analytic diagnosis of transformer winding deformation. The transformer winding deformation diagnostic method comprises performing decomposition process on a measured waveform obtained by virtue of frequency response analysis and a reference waveform at a plurality of layers by virtue of discrete wavelet transform, and then performing mathematical statistical analysis by use of the processed smooth data and diagnosing the deformation degree of a transformer winding according to a corresponding criterion. Such a diagnostic mode is capable of effectively reducing the errors of a traditional diagnostic mode due to white noise interference during frequency response measurement and some local relatively strong interference points and accurately diagnosing the deformation degree of the transformer winding, and therefore, a new judgment method is provided for estimating transformer fault types and the development trend of faults.

Description

technical field [0001] The invention relates to the field of transformer winding deformation diagnosis, in particular to a transformer winding deformation diagnosis method based on discrete wavelet transform. Background technique [0002] According to incomplete statistics of the State Grid Corporation of China, during the five-year period from 2002 to 2006, there were 162 transformer accidents with a voltage level of 110kV and above in the State Grid System, which has become a major challenge for the power system to achieve safe and stable operation. serious problem. Especially when the main transformer is directly connected to the generator, its damage will force the generator to stop generating power. An accident occurs when a large power transformer is running in the system, which may cause a large-scale power outage. It is very difficult to repair the damaged coil. The maintenance period generally takes more than half a year, which costs a lot and affects a wide range ...

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Problems solved by technology

The short-circuit impedance method is a traditional method for judging winding faults, which has the advantages of short time consumption, but the sensitivity is not high; the vibration signal analysis method judges the state of the transformer based on the vibration signal on the oil tank, which cannot fully reflect the short-circuit fault of the winding. There are many influencing factors; the frequency response analysis method is a method to measure and analyze the frequency response characteristics of windings in a wide frequency band, and judge the winding state. It has the advantages of high sensitivity, simple wiring, and wide frequency bandwidth. It has been widely used in transformer windings. Deformation detection

[0004] However, further studies have shown that the frequency response analysis method still has the following defects or deficiencies: it is easily interfered by background noise, low-frequency resolution is low, and the excitation source energy is limited.

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