Motor rotor classical failure diagnosis method based on low subharmonic shaft voltage signals

Abstract

The invention relates to a motor rotor classical failure diagnosis method based on low subharmonic shaft voltage signals, which is used for solving the detection problem of turn-to-turn short circuit failure of a motor rotor static eccentricity and a winding. The technical scheme is achieved as follows: respectively connecting two ends of a slide rheostat to two ends of a motor rotor; acquiring shaft voltage partial signals output by the slide rheostat in an on-line way by using a data acquisition device; carrying rapid Fourier transform on the signals to obtain a shaft voltage frequency spectrum plot; and analyzing the frequency spectrum of the shaft voltage signals, diagnosing whether the turn-to-turn short circuit failure exists in the motor rotor winding or not: if the frequency component amplitude of j Omega r / 2Pi in the shaft voltage signals exceeds 15 percent of the normal value, judging the turn-to-turn short circuit failure exists in the motor rotor winding, wherein Omega r is the mechanical angular velocity of the motor. The invention has high diagnosis reliability, simple operation and low cost, is suitable for a non-salient pole sychronous motor and a salient pole synchronous motor, and can conveniently perform the test whatever the motor is big, small, new or old.

Description

technical field [0001] The invention relates to a method capable of diagnosing on-line whether there are typical faults such as inter-turn short circuit in the rotor winding of a synchronous motor, belonging to the technical field of testing. Background technique [0002] Turn-to-turn short circuit fault of rotor winding is a common fault of synchronous motor. There are various diagnosis methods for inter-turn short circuit faults, which can be generally divided into two categories, namely offline diagnosis methods and online diagnosis methods. Among them, the online diagnosis method can detect the fault in real time and prevent it from further deterioration, which is the trend of future development. [0003] At present, the methods for online detection of inter-turn short-circuit faults in rotor windings mainly include detection coil method, excitation current method and detection method based on rotor fundamental frequency vibration. [0004] The basic principle of the d...

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Problems solved by technology

This method should leave a certain margin for system disturbance and power regulation, and is more effective for severe short circuits, while slight inter-turn short circuits (such as 1-turn short circuit) are usually difficult to detect

[0006] The rotor winding turn-to-turn short-circuit fault monitoring method based on the fundamental frequency vibration of the motor rotor monitors the vibration signal of the rotor. Due to the phase opposite between the initial unbalanced external force and the unbalanced magnetic pull caused by the short circuit between the rotor turns, the fundamental frequency vibration of the motor may still be in the normal range after the short circuit occurs, and the fault cannot be detected

[0007] In the late last century, Paul I. Nippes proposed a method of diagnosing rotating machinery faults through shaft voltage after a lot of practice. It is based on abnormal voltage waveforms and sudden increases in amplitude. It has been applied and successfully diagnosed generator faults several times, but it has not received theoretical support, and it is difficult to give a clear indication of the fault type

[0008] In short, although the online detection of inter-turn short-circuit faults of rotor windings has been paid great attention at home and abroad, the existing methods are still subject to certain restrictions in application, and the results obtained in actual tests are not very ideal. There are many cases where inter-turn short circuit faults are not detected in time, so it is necessary to further improve the diagnosis level of such faults

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