JPH0345145A - Torsional vibration measuring device for shaft of electrical rotary machine - Google Patents

Abstract

PURPOSE:To improve detection sensitivity and reliability by employing two piezoelectric acceleration sensors having rigid structure and high detection sensitivity and providing acceleration signal to static section. CONSTITUTION:Vibration acceleration signals in the coupling direction of rotary shaft, detected through piezoelectric acceleration sensors 1a, 1b, are oscillated through oscillators 2a, 2b being driven by batteries 3a, 3b and transmitted through oscillation antennas 4a, 4b. The transmitted wave is received by a receiving antenna 5 installed at static side and distributed through a distributor 6 to respective receivers 7a, 7b where the distributed wave is demodulated to acceleration signals corresponding to the acceleration sensors 1a, 1b. A signal processor 8 analyzes the frequency and obtains the phases of signals fed from both acceleration sensors, and if the polarity of both sensors indicates same rotary direction inphase component is judged to be the torsional vibration component and extracted while if the polarity indicates reverse rotary direction the reverse phase component is judged to be torsional vibration component and extracted. Furthermore, level of rotary frequency component of electrical rotary machine may be compared with a predetermined level in order to judge normal system operation.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a shaft torsional vibration measuring device for a rotating electric machine.

(Prior art) Recently, in shaft torsional vibration of turbine generators, etc., it is caused by the unbalance of the load and the natural vibration of a higher mode that exists around twice the power generation frequency coupled with the bending vibration of the turbine blades. Serious accidents have occurred that are thought to be caused by a resonance phenomenon with torque pulsation at a frequency twice the power generation frequency. Therefore, it is necessary to understand the natural frequency around twice the power generation frequency, and if it is too close, take measures to separate it from twice the power generation frequency. Up until now, the measurement device for shaft torsional vibration has been to install gears and electromagnetic pickups facing each other at two locations in the longitudinal direction of the shaft, and to calculate the torsion angle from the phase difference of the signals that alternate between each tooth of the gear. there were.

(Problem to be solved by the invention) This device can measure low-order eigenmode torsional vibrations with relatively large axial torsional displacements, but cannot measure high-order eigenmode vibrations with relatively small axial torsional displacements. The same method is used for measuring by attaching a strain gauge to the surface and using an FM telemetry system.

In particular, it is desirable to have a torsional vibration measuring device that can measure minute vibrations and has a high detection sensitivity, since there is a risk of damaging the turbine generator and it is necessary to refrain from exciting the natural frequency to a large extent.

As described above, the conventional shaft torsional vibration measuring device has insufficient detection sensitivity for measuring high-order mode torsional vibration.

The present invention has been made in response to such circumstances, and an object of the present invention is to provide a shaft torsional vibration measuring device for a rotating electrical machine that has high detection sensitivity and high reliability.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the shaft torsional vibration measuring device for a rotating electric machine of the present invention is provided in a rotating part of a one-rotation type machine, and the detection direction is aligned with the rotation direction and the rotation axis is symmetrical. A pair of piezoelectric acceleration sensors attached, a transmitter that transmits the detection signal of this sensor, a power source that drives this transmitter, an antenna connected to the transmitter, and a transmitter that transmits the detection signal provided on a stationary part. a receiving antenna that receives the vibration, a distributor connected to the receiving antenna, a receiver connected to the distributor that extracts each vibration waveform obtained from the sensor, and a receiver that frequency-analyzes the vibration waveform and extracts each vibration frequency component. determine whether the phase is the same or the opposite phase, extract the vibration component corresponding to the pre-specified phase, and determine whether the vibration level of the rotational frequency component of the rotating electric machine is within a predetermined level range. The configuration includes a signal processing device having functions.

(Function) The present invention is configured as described above, and the vibration acceleration signal in the tangential direction of the rotating shaft detected by the piezoelectric acceleration sensor is transmitted by a transmitter driven by a power source on a radio wave from a transmitting antenna. The signal is received by a receiving antenna provided on the stationary side, distributed to each receiver by a distributor, and demodulated into an acceleration signal corresponding to each acceleration sensor. Then, the frequency is analyzed by a signal processing device, and the phase of the signals of both acceleration sensors is also determined. If the polarities of the sensors are installed with both facing the same rotation direction, the in-phase component is installed with the polarities facing in the opposite direction. If so, the negative phase component can be determined to be a torsional vibration component and extracted. It is also possible to determine whether the system is operating normally by comparing the level of the rotational frequency component of the single-rotation machine with a predetermined level.

(Example) An embodiment of the present invention will be described with reference to the drawings.

In the figure, la and 1b are piezoelectric acceleration sensors that have higher acceleration detection sensitivity and stronger structure than strain gauge types, and are stable against rotational centrifugal force.
a transmitter 2a that modulates the acceleration signal and transmits it as a radio wave;
2b, and these driving batteries 3a, 3b, and are molded and embedded in the head of a bolt (not shown) of a coupling 9 of a turbine generator at an axially symmetrical position so that the detection direction is in the same rotational direction. It is.

The transmitting antennas 4a and 4b are fixed to the surface of the turbine generator shaft with an adhesive-coated glass string or the like so as not to scatter, and are connected to the transmitter. The receiving antenna 5 is fixed near the transmitting antennas 4a and 4b so as to revolve around an axis. The receiving antenna 5 is connected to the receiver 7a via a distributor 6 which supplies average radio waves to each receiver.

7b. Then, the outputs of the receivers 7a and 7b have a function to perform frequency analysis to find the phase between signals and extract the frequency of a predetermined phase component, and a function to compare the level of the rotational frequency component of the turbine generator with a predetermined level. The signal is guided to a signal processing device 8 having a pass/fail determination function.

When the turbine generator equipped with the shaft torsional vibration measuring device configured as described above rotates and some torsional vibration occurs, the vibration acceleration signal detected by the piezoelectric acceleration sensors la and lb is transmitted to the battery 3a. , 3b are driven by generators 2a and 2b, and the radio waves are carried by the transmitting antenna 4.
a, 4b. This signal is received on the stationary side by a receiving antenna 5, and is equally supplied to receivers 7a and 7b by a distributor 6, where it is demodulated into the original acceleration waveform. This acceleration waveform is frequency-analyzed by a signal processing device 8 to determine the phase of the signals from both sensors. This acceleration signal includes not only torsional vibration components but also lateral vibration components and components associated with rotation. The signal processing device 8 determines that the in-phase component is a torsional vibration component and extracts that component. At the same time, the signal processing device 8 compares the component accompanying the rotation, that is, the level of about ±1 G per rotation, with a predetermined level, and the system of the rotating part It can also be determined that it is operating normally.

In addition, in the conventional gear system, the detection sensitivity is determined by the gear pitch and the response of the phase difference detection section, and the maximum sensitivity is about 0.25 degrees at full scale, and the acceleration sensor is
, when attached to a coupling bolt at a position of 5 m 1
If ±0.25° torsional vibration occurs at 00Hz, the acceleration value of this group is approximately ±130G, and since the full scale can be raised to ±IG to confirm the normality of the 1-rotation section, it can be detected 100 times more. Sensitivity can be increased.

In this embodiment, since a battery is used to drive the transmitter, the battery and the acceleration sensor can be integrally molded, and the system can be simplified.

As another embodiment, in the above embodiment, a battery was used as the power source for driving the transmitter, but for long-term measurements, an induction power supply device may be used to continuously supply power from a stationary part. .

〔Effect of the invention〕

As explained above, according to the present invention, two piezoelectric acceleration sensors with a strong sensor structure and high detection sensitivity are used to send an acceleration signal to a stationary part using a system, resulting in high sensitivity and high reliability. It is also possible to provide an apparatus for measuring shaft torsional vibration of a rotating electric machine which has the following characteristics and can also check the operation of the system of the rotating part by checking the signal level of approximately ±IG generated during one rotation.

[Brief explanation of drawings]

The figure is a configuration diagram showing an embodiment of the present invention. la, lb...piezoelectric acceleration sensor 2a, 2b.
...Transmitter 3a, 3b...Battery 4
a. 4b... transmitting antenna 5... receiving antenna 6... distributor 7a. 7b...Receiver 8...Signal processing device

Claims (1)

[Claims] A pair of piezoelectric acceleration sensors installed in the rotating part of a rotating electric machine, whose detection direction is aligned with the rotation direction and mounted at a position symmetrical to the rotation axis, a transmitter that transmits the detection signal of this sensor, and a transmitter that drives this transmitter. an antenna connected to the transmitter, a receiving antenna provided on a stationary part and receiving the detection signal, a distributor connected to the receiving antenna, and a power supply connected to the distributor and receiving the detection signal from the sensor. a receiver that extracts each vibration waveform, and a receiver that analyzes the frequency of the vibration waveform, determines the phase of each vibration frequency component, determines whether it is the same phase or opposite phase, extracts the vibration component corresponding to a pre-specified phase, and rotates the vibration waveform. 1. A shaft torsional vibration measuring device for a rotating electrical machine, comprising: a signal processing device having a function of determining whether a vibration level of a rotational frequency component of the electrical machine is within a predetermined level range.