A Method of Using Wavelet Transform to Extract Vibration Signal Index Quantities Characterizing the Operating State of On-load Tap Switches

Abstract

The invention provides a method for extracting a vibration signal index quantity representing the operating state of an on-load tap changer by using wavelet transform, which belongs to the field of power system fault detection. After obtaining the envelope of the high-frequency vibration signal of the on-load tap changer, the maximum value of the wavelet transform modulus is obtained for the envelope of the high-frequency vibration signal, and the maximum value of the modulus is used to accurately extract the difference between the first mutation amount and the largest mutation amount. Time t1 and switch switching action time t2, and then use t1 and t2 to obtain the maximum amplitude f1 and f2 in the vibration high-frequency signal envelope within two periods of time, and use t2, f1 and f2 to judge the operating state of the on-load tap changer . When f1 is greater than the threshold value, it is judged that the driving mechanism of the OLTC is insufficiently lubricated, otherwise, it is normal; when t2 is not within the threshold range and f2 is less than the threshold value, it is judged that the spring force of the OLTC is weakened, and on the contrary , it is normal. The simulation experiment proves that the method transforms the analysis of the sudden vibration signal into the analysis of its modulus maximum value, and the method is effective.

Description

technical field [0001] The invention relates to a method for extracting a vibration signal index quantity representing an operating state of an on-load tap changer by using wavelet transform, and belongs to the technical field of power system fault detection. Background technique [0002] In the on-load tap changer, the on-load tap changer is the key device. The on-load tap changer is the only part of the transformer that operates under high voltage and high current, and its failure rate is relatively high, accounting for 41% of the on-load tap changer failures. Aiming at the fault characteristics of the on-load tap changer, the relevant research at home and abroad is mainly focused on the vibro-acoustic detection and the current detection of the drive motor. Among them, it is very important to extract the vibration signal index of the operating state of the on-load tap changer. At present, the commonly used detection methods include dynamic impedance measurement, thermal ...

AI Technical Summary

Problems solved by technology

At present, the commonly used detection methods include dynamic impedance measurement, thermal image analysis, and dissolved gas analysis, but there are few types of faults that can be judged, some defects are not easy to find, functions are not perfect, and only care about the calculation results of mechanical parameters.

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