Non-invasive online detection method and system for rotor broken-bar fault of three-phase cage type asynchronous motor

Abstract

The invention provides a non-invasive online detection method and system for a rotor broken-bar fault of a three-phase cage type asynchronous motor. The detection system comprises a data acquisition system and a virtual platform. The detection method comprises the following steps of: acquiring any one phase of stator current of the three-phase cage type asynchronous motor by the data acquisition system; measuring a base frequency f0 of a stator current signal by the virtual platform and carrying out filtering and spectrum zoom on the stator current signal; finding and accurately measuring a groove harmonic component of the motor to carry out timely accurate measurement on a slip ratio s of the motor; and carrying out online detection to detect whether the motor has the rotor broken-bar fault through accurately searching whether a characteristic component of the rotor broken-bar fault exists. According to the invention, the problem that a rotor broken-bar fault signal spectral line is annihilated by a stator current fundamental harmonic signal spectrum is effectively solved. Meanwhile, the problem of erroneous judgment caused by influences of fluctuation of load, power supply harmonic and other interference signals is further solved; and therefore, the method and the system provided by the invention have the advantages of simplicity in operation, high flexibility and the like.

Description

technical field [0001] The invention belongs to the technical field of detection, and in particular relates to on-line accurate detection of a cage-type asynchronous motor rotor broken bar fault. Background technique [0002] Three-phase asynchronous motor is widely used in electric power, metallurgy, petroleum, chemical industry, machinery and other fields because of its simple structure, low price and reliable operation. It is the most widely used motor. However, three-phase cage-type asynchronous motors often have broken rotor bars, and the probability of failure is as high as 10%. This will not only damage the motor itself, but also affect the normal operation of the entire system, and even endanger personal safety, resulting in huge economic losses. . For a long time, for various serious faults of large motors, various relay protection measures have been adopted. Commonly used protections include grounding protection, overcurrent protection, differential current prote...

AI Technical Summary

Problems solved by technology

However, these methods have the following problems: misjudgment may occur due to the influence of fundamental frequency current and external interference factors, and no practical and effective solution to the signal interference problem is proposed; since the slip of the motor is a dynamic variable, the spectrum analysis of the current can be obtained Whether the spectral line of the motor is the characteristic spectral line of the broken bar fault has not been studied

Images