JPS5833781B2 - Turbine generator shaft monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for monitoring shaft fatigue of a turbine generator.

A schematic configuration diagram of a conventional turbine generator shaft system is shown in block form in FIG.

In the figure, 1 is a generator rotor, 2 is a turbine, 3 is an exciter,
4 is a shaft that connects the turbines, the turbine and the generator, and the generator and the exciter.

In a turbine generator configured in this way,
Shock torque is applied to the shaft 4 during sudden short circuits, re-closing, etc., and the shaft 4 causes torsional vibration due to the inertia rate of the turbine, generator, etc. and the torsional vibration system created by the shaft, and this torsional vibration The shaft material may become fatigued.

In this case, since the magnitude of the impact torque and the number of times it occurs are uncertain, the magnitude and number of times of the shaft torque generated by torsional vibration are uncertain, and there is a problem that the fatigue level of the shaft is not clear.

The present invention was made in order to monitor the degree of fatigue of the shaft as described above, and an object of the present invention is to provide a shaft monitoring device that measures the torque applied to the shaft and monitors the safety level of the shaft. .

Embodiments of the present invention will be described below based on the drawings.

FIG. 2 is a block diagram showing a turbine generator shaft system in which the shaft monitoring device of the present invention is installed.

In the figure, 5 is a gear for detecting rotational pulses attached to the shaft, 6 is a pulse generator such as a magnetic sensor, 7 is a rotational unevenness detector, 8 is a generator output line, 9 is a power measuring device, 10
1 is an arithmetic unit, and 11 is an indicator.

In this embodiment, the axis monitoring device of the present invention includes a pulse generator 6, a rotation unevenness detector 7, a power measuring device 9, and an arithmetic device 10.
and an indicator 11.

In the shaft monitoring device configured as described above, the pulse generator 6 generates pulses with a pulse frequency proportional to the rotational speed of the shaft 4, and the rotational unevenness meter 7 measures fluctuations in the pulse frequency to detect torsional vibrations of the shaft 4. Detect.

This detects the alternating current component of fluctuations related to the relative torsion angle between two points on the shaft.

Then, since the output of the generator is measured by the power measuring device 9, the torque is determined from this and the rotational speed of the generator.

In this case, the rotation speed can be obtained from the frequency of the detected voltage of the generator output line 8, and also by counting the output pulses of the pulse generator 6.

The torque at this time is a direct current component and a component related to the power supply frequency, and the latter mainly consists of the fundamental wave and harmonic components of the power supply frequency.

Furthermore, the relationship between the shaft torque due to torsional vibration of the shaft system of the turbine 2 and the generator rotor 1 and the rotation unevenness occurring in the gear 5 is separately determined, and this characteristic is stored in the arithmetic unit 10.

In this way, from the rotational unevenness signal from the rotational unevenness meter 7 and the characteristics of rotational unevenness and shaft torque stored in the calculation device 10,
The arithmetic unit 10 calculates the shaft torque due to torsional vibration of the shaft system applied to a certain point on the shaft.

This is an alternating current component.

On the other hand, using the power and frequency detected by the power measuring device 9, the arithmetic unit 10 calculates the torque applied to the generator rotor 1, and then calculates the shaft torque at the above-mentioned point due to this torque, and calculates the shaft torque due to torsional vibration of the shaft system. Add torque.

The added torque becomes a curve C shown in FIG.

The torque represented by this curve C is the shaft torque.

The arithmetic unit 10 determines the stress of the shaft from this shaft torque and the diameter of the shaft 4, and calculates the frequency of the stress by determining, for example, the peak value of the stress and the number of times.

This cumulative frequency is indicated by indicator 11.

For example, if the stress time waveform is a waveform that fluctuates as shown in Figure 4, the stress level is divided into sections of levels 1 to 3, and the number of times the stress peak value falls in each section is calculated to determine the stress level. The data on the number of times, that is, the frequency of stress is counted and the frequency is shown on the indicator 11 for each stress level.

Further, as a frequency counting method for stress, the calculation device 10 may use the known Raincrot method, range pair counting method, or the like.

Therefore, based on data on the frequency of these stresses, the remaining life of the shaft member at that time is estimated by the calculation device 10 using data constants such as the S-N curve (stress-rupture repetition rate) of material fatigue. , by outputting the value from the indicator 11, the safety degree of the shaft can be known.

In this way, the stress applied to the shaft and the cumulative stress frequency, which includes the number of times the stress is applied, are indicated, and the safety level of the shaft can be known.

Note that the torsional vibration of the shaft can be measured by using a wow, flutter meter, etc. as the rotational unevenness meter 7, but it does not measure the relative torsion angle between two points on the shaft, so the relative torsion angle, that is, the shaft Torque cannot be found.

However, if the vibration component is determined in advance by determining the characteristics of the shaft system, the torque force and output point are known, and the shaft torque due to torsional vibration of the shaft system can be determined by calculating backwards from the shaft torsion angle at one point.

On the other hand, the torque from the generator rotor 1 can be determined by dividing the output power from the power measuring device 9 by the rotational speed.

Therefore, as described above, by adding the torque from the generator rotor to the shaft torque due to torsional vibration of the shaft system, the torque applied to the shaft can be determined, and the stress on the shaft can also be determined.

In the above embodiment, the gear 5 was attached to the exciter 3 at the end of the shaft system, but it may be mounted anywhere on the shaft system.

For example, it may be between the exciter 3 and the generator rotor, or between the generator rotor and the turbine.

In addition, although the gear 5 is used, other gears may be used as long as it is suitable for measuring rotational unevenness. Instead of the gear 5, a black and white striped tape is attached to the rotating shaft to optically pulse the rotation. You may take it out.

Alternatively, a commonly used encoder may be used.

The pulse generator 6 may be a magnetic sensor or an optical sensor.

As the rotational unevenness meter 7, a wow/flutter meter, a jitter meter, etc. can be used.

The arithmetic device 10 may be either an analog or digital arithmetic device.

Alternatively, both may be used.

As explained above, according to the present invention, a rotational irregularity meter is provided in a turbine generator, which has a gear or the like on its shaft, generates a pulse proportional to the rotational speed with a pulse generator, and detects rotational irregularity from the pulse signal. On the other hand, it is equipped with a power measuring device that measures power from the voltage and current of the generator, and calculates the shaft torque due to torsional vibration of the shaft system from the signal of the rotational irregularity meter, and also calculates the shaft torque due to torsional vibration of the shaft system from the signal of the rotational irregularity meter. Determine the torque applied to the generator rotor from the power waveform and rotational speed, add it to the shaft torque above to determine the instantaneous value of the torque applied to the shaft, determine the stress on the shaft, calculate the magnitude and frequency of stress, and determine the material By providing a computing device that calculates the degree of safety against fatigue of the shaft, the degree of fatigue of the shaft can be monitored.

[Brief explanation of drawings]

Fig. 1 is a block diagram schematically showing a conventional turbine generator, Fig. 2 is a block diagram schematically showing a turbine generator equipped with the shaft monitoring device of the present invention, and Fig. 3 is a block diagram schematically showing the shaft torque of the turbine generator. The graph showing the waveform, FIG. 4, is a graph explaining the frequency counting method with respect to stress. 1: Generator rotor, 2: Turbine, 3: Exciter, 4: Shaft, 5: Gear, 6: Pulse generator, 7: Rotation irregularity meter, 9:
Power measuring device, 10: Arithmetic device, 11: Indicator. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1 A pulse generator that generates electric pulses with a frequency proportional to the rotational speed of the turbine generator shaft, a rotational unevenness detector that receives the electric pulses, a power measuring device that measures the output of the generator, and a signal from the rotational unevenness meter. Calculate the shaft torque generated on the turbine generator shaft due to shaft system torsional vibration of the turbine generator shaft, and also calculate the DC component and power frequency component of the torque applied to the turbine generator by dividing the power measurement value by the power measuring device by the rotation speed. A shaft monitoring device for a turbine generator, comprising an arithmetic device that calculates the magnitude and frequency of the stress by determining the stress of the turbine generator shaft by determining the instantaneous value of the torque by adding the torque to the shaft torque due to the torsional vibration.