Method and device for measuring low-frequency and small-range vibration signals

Abstract

The invention provides a method and device for measuring low-frequency and small-range vibration signals. The method mainly comprises the steps that an acceleration sensor is arranged on a measured object; after the low-frequency and small-range vibration signals sent by the measured object are detected by the acceleration sensor, the low-frequency and small-range vibration signals are converted to vibration acceleration signals; the integration-amplification vibration acceleration signals are output, and the resonant frequency of an integration-amplification acceleration sensor is larger that the largest effective vibration frequency of the vibration signals sent by the measured object; primary integration amplification is conducted on the vibration acceleration signals output by the integration-amplification acceleration sensor so that vibration speed signals can be obtained, and secondary integration amplification is conducted on the integration-amplification vibration speed signals so that vibration displacement signals can be obtained. According to the method and device for measuring the low-frequency and small-range vibration signals, the problem of the failure of the measured signals due to the phenomena of mechanical fatigue and blocking of mechanical components and the like is effectively solved, the resonant frequency of the acceleration sensor is far higher than the largest effective vibration frequency of the measured objects such as the structure of a water-turbine generator set, resonance signals of the acceleration sensor are completely filtered, and the function that a rear-end circuit is not influenced by the resonance signals of the acceleration sensor is guaranteed.

Description

technical field [0001] The invention relates to the technical field of vibration measurement, in particular to a method and device for measuring low-frequency, small-amplitude vibration signals. Background technique [0002] In the field of vibration measurement of hydro-generator units, since the rated speed of the unit is distributed between 60r / min and 1000r / min, the vibration signals of the unit frame, foundation and other components are low-frequency and small-amplitude vibration signals, and in the low-frequency band, especially Below 1 Hz, because the vibration acceleration and vibration velocity values ​​of the vibration signal are very small, only the vibration displacement can be used as the basis for evaluating the vibration state of the unit. [0003] A low-frequency vibration sensor in the prior art is a contact-type ultra-low-frequency magnetoelectric inertial vibration sensor, which can measure the absolute vibration of the frame and foundation of the hydroele...

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Problems solved by technology

[0007] Since the seismic geophone is equipped with mechanical devices such as inertial mass, coil and spring damping, it is extremely prone to mechanical fatigue and jamming during long-term operation, resulting in the actual measurement of the vibration signal of the measured object and the service life of the sensor. shorten

[0008] 2) Measurement error and frequency compensation circuit failure due to seismic geophone resonance

When the seismic geophone is resonated, the output of the geophone not only cannot guarantee the accuracy of the measurement, but also introduces a vibration signal of a false frequency. At the same time, the resonance signal is amplified by the frequency compensation circuit at the back end, which is extremely easy to cause The failure of the frequency compensation circuit will cause the unreliability of the measurement signal and greatly reduce the measurement accuracy of the vibration signal of the measured object

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