Study on Envelope Extraction Method of Vibration Signal of OLTC Based on Savitzky-Golay Filter
During the switching process of the on load tap changers(OLTC),each contact collides in sequence in closing and opening operation and generates vibration signal.The signal's characteristics reflects the collision ener-gy and stiffness of the contacts.In order to study the dynamic characteristic of the contact collision,the collision dy-namic model with 4 contacts of M-type OLTC is set up firstly,and the influence of static contact stiffness on the re-sponse characteristic of the model is calculated.Then,the spring relaxation fault of the stationary contact is simulat-ed and the corresponding vibration signal of spring with wire diameter of 0.6 mm and 1.0 mm are obtained.After that,the envelope calculation method based on Savitzky-Golay filter is proposed to extract the average envelope of vi-bration signal during the odd position to the even position and the opposite.Finally,the correlation coefficients of the average envelope corresponding to the static spring of the two wire diameters are calculated.The study results show that the natural frequency of the contact collision system decreases with the decreasing stiffness of stationary contact,consequently leads to a slower response speed of the contact collision and the time delay of the first peak of the vibra-tion signals.Furthermore,the correlation coefficient of the average envelopes is only 1.6,indicating a significant vari-ation of the vibration signal caused by the change of stiffness of the contact.The study conclusion can be used in the diagnosis of the contact condition of the OLTC.
on-load tap changercontact collisiondynamic modelvibration response
万方数据
维普
