JPH05149782A - Device for monitoring torsional vibration of rotating body - Google Patents

Abstract

PURPOSE:To enable the title device to surely recognize the actual condition of the torsional vibration of a rotating body by obtaining information at fault occurring time and, at the same time, to improve the measuring accuracy of the device by preventing the intervention of disturbances at the time of starting and stopping a CPU. CONSTITUTION:In this device for monitoring torsional vibration of rotating bodies, a torsion measuring signal is inputted not only to an A/D converting section, but also to a monitor 21 and alarm/trigger circuit 22. The monitor 21 generates an alarm and trigger signals upon detecting a fault from the torsion measuring signal. The A/D converting section is composed of an A/D converter 9 and buffer memory 23 and temporarily stores measured data about twisting angle displacement and twisting angular velocity in the memory 23. A CPU 10 performs arithmetic operation on the information stored in the memory 23 by tracing the information backward from the alarming time to the fault occurring time in accordance with a command from the circuit 22 and displays an obtained vibration waveform on a display device 11. At the same time, the CPU 10 records the waveform on a hard disk 12, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a steam turbine rotor,
The present invention relates to a torsional vibration monitoring device for a rotating body such as a gas turbine rotor.

[0002]

2. Description of the Related Art Modern electric power systems have various electrical disturbances, and an exciting electric torque is applied to the body of a generator rotor. Furthermore, in steam turbines for thermal power and nuclear power generation, the moment of inertia of the low-pressure turbine rotor equipped with long blades is much larger than the moment of inertia of the generator rotor. It is in.

FIG. 3 is a diagram showing the principle of torsional vibration generation in a rotary shaft system. In rotating body axial system shown in the figure, when the torque variation T _1, such as impact damping moment of inertia I ₁ is operated, not sufficiently large enough moment of inertia I ₁ is sufficient to absorb the torque change, the moment of inertia When the residual moment of inertia I ₂ other than I ₁ is sufficiently large and the shaft rigidity K ₂₁ is small, torsional vibration of the shaft system is excited.

In the turbine / generator shaft system, bending vibration and torsional vibration are mainly problems. For bending vibration, the shaft vibration of the journal part, which is an important index for operating turbines / generators, is usually directly monitored. Vibration was also not monitored. However, in recent years, the opportunities for torsional vibration have increased due to the following factors.

1. High-speed reclosing (Hi
There are many electrical disturbances such as lightning strikes associated with gh speed reclosing (HSR), three-phase steady unbalance, and line switching, which excite torsional vibrations of the turbine / generator shaft system.

2. In order to increase the transmission capacity, a series capacitor may be inserted in the transmission line. At this time, the sum of the "electrical natural frequency of the power system" and the "torsion natural frequency of the turbine / generator shaft system" is the system frequency. When the instantaneous value is matched, the sub-synchronous resonance (Sub-Synchronous
Resonance: SSR) occurs. This is self-excited vibration caused by double resonance between electric vibration of the electric power system and torsional vibration of the shaft system.

In recent years, troubles caused by such torsional vibrations have occurred, and in order to prevent damages and accidents caused by the damages, the number of power generation plants equipped with torsional vibration monitoring devices is gradually increasing. FIG. 4 is a block diagram of a conventional torsional vibration monitoring device, and shows an example of a 600 MW class tandem compound 3-cabin 4-split exhaust thermal power turbine.

In FIG. 4, a high-pressure / intermediate-pressure turbine 1, a low-pressure first turbine 2 and a low-pressure second turbine 3 are shaft coupling portions 4.
Is connected to the generator (GEN) 5 via. An electromagnetic pickup (not shown) is provided on the bearing stand and the shaft ends 4a and 4b of each shaft coupling portion 4, and a detection signal of the electromagnetic pickup is transmitted through a preamplifier PA to a torsion angle displacement meter (T
AM) 6a to 6c and a torsion angular velocity meter (AVM) 7 are input. In addition, in FIG. 4, one system of the preamplifier P is provided.
A is provided. Signals sent from an electromagnetic pickup provided at the shaft end 4a via a preamplifier 8 are input to clock terminals of the torsion angle displacement meters 6a to 6c and the torsion angular velocity meter 7. The system of this preamplifier 8 is
This is for taking in a signal of one pulse every time the turbine makes one revolution, for example, and the torsion angle displacement meter 6a ...
6c and the torsional angular velocity meter 7 are synchronized with the signal acquisition, and the pitch unevenness of the key is corrected.

The torsional angular displacement signals output from the torsional angular displacement meters 6a to 6c and the torsional angular velocity signal output from the torsional angular velocity meter 7 together with the synchronizing pulse signal output from the preamplifier 8 together with the A / D converter 9 are used. Sent to. Further, the A / D converter 9 has a voltage measuring signal PT from a voltage measuring device (not shown) for measuring the voltage of the generator (GEN) 5,
And a current measurement signal CT from a current measuring device (not shown) for measuring the current.

The A / D converter 9 converts each of the above-mentioned measurement signals into a digital signal and converts it into a CPU (Central Processing Unit).
: Central processing unit) 10. This CPU1
0 is a display device (CRT) 11 and a hard disk 1
2, a magnetic tape (CMT) 13, a printer 14, etc. are connected.

FIG. 5 is a diagram for explaining the principle of the torsional vibration monitoring device. The twist angle of each shaft coupling part 4 is measured by a twist angle displacement gauge 6a ...
6c and the torsional angular velocity meter 7 (step A1
), Converted into digital data by the A / D converter 9 and sent to the CPU 10. The CPU 10 decomposes the waveform signal of the measured twist angle into a mode waveform (step A2) and multiplies this by a count determined by each natural vibration type,
The stress waveform at the monitoring point is calculated (step A3). And
This stress value is compared with a preset threshold value (step A5), and when the stress value reaches a level above the threshold value, an alarm is issued and a series of waveform signals are stored in the hard disk 12 and the magnetic tape 13. Then, the data is displayed on the display device 11 and printed and recorded by the printer 14 (step A6). The CPU 10 also performs self-excited vibration analysis based on the resonance of the electric power system and the shaft system based on the voltage measurement signal PT, the current measurement signal CT, and the like. Furthermore, CPU1
For 0, the life consumption of the monitoring point is calculated based on the last stored data and compared with the set value (steps A4, A
5) If the value exceeds the set value, alarm generation processing is performed (step A6).

[0012]

As described above, the torsional vibration of the rotating body can be monitored. However, as shown in FIG. 6, the vibration stress at the monitoring point does not become the maximum upon the occurrence of a failure, but it may be a little. It becomes maximum after a lapse of time T seconds. In the case of FIG. 6, the set stress is reached after the elapse of t seconds, at which time an alarm is issued and the recording of torsional vibration is started. For this reason, the information at the time of the failure was not obtained, and the substance of the vibration could not be grasped with certainty.

Further, the conventional torsional vibration monitoring device operates from the start of the turbine to the stop thereof. On the other hand, the torsional vibration of the turbine / generator shaft system occurs due to lightning strikes to the power transmission system, switching of the system, or the like when the generator is connected to the power transmission system as described above. Therefore, from the start up to the connection to the power system, or from the disconnection to the stop, the signal is invalid, and a minute deviation between the invalid signals of this kind that always operates the CPU 10 causes disturbance in the signal system, and the vibration measurement accuracy is improved. Is decreasing.

The present invention has been made in view of the above circumstances, and it is possible to surely grasp the actual state of torsional vibration by obtaining information at the time of failure occurrence, and to prevent the intervention of disturbance at the time of starting and stopping the CPU. An object of the present invention is to provide a torsional vibration monitoring device for a rotating body that can improve measurement accuracy.

[0015]

[Means for Solving the Problems]

(1) According to the present invention, in a torsional vibration monitoring device for a rotating body, a twisting measuring means for measuring a twisting state of a rotating shaft and a signal measured by this means are monitored to detect an occurrence of a failure and issue an alarm signal. Monitor means for outputting, buffer memory for storing the signal measured by the twist measuring means for a certain period, and when an alarm signal is output from the monitor means, information stored in the buffer memory is traced back from the time of alarm to the time of failure occurrence. And a CPU for displaying a vibration waveform on a display device.

(2) The monitor means for monitoring the measurement signal is characterized by having an interlock function which is activated when a signal indicating that the generator is connected to the power system is input. Is.

[0017]

The signal measured by the measuring means is always stored in the buffer memory for a fixed period. On the other hand, the monitor means
Whether or not a failure has occurred is monitored from the measurement signal, and an alarm signal is output when a failure is detected. When this alarm signal is output, the CPU traces back the time based on the information stored in the buffer memory to obtain the torsional vibration from the time of the occurrence of the failure, and displays it on the display device.

As described above, the measurement signal is always stored in the buffer memory for a certain period, so that the mode waveform can be decomposed and the monitoring point stress waveform can be obtained from the alarm occurrence time to the failure occurrence time. You can grasp the actual situation.

Further, by providing the monitor means with the interlock function, the CPU operates only while the generator is connected to the power system. Therefore, the CPU
It is possible to improve the measurement accuracy without the disturbance during the stoppage.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a torsional vibration monitoring device for a rotating body according to an embodiment of the present invention. The same parts as those of the conventional torsional vibration monitoring device shown in FIG. .. As shown in FIG. 1, a torsion angle displacement meter (TAM) 6
The torsion angular displacement signals output from a to 6c and the torsion angular velocity signal output from the torsion angular velocity meter (AVM) 7 are A /
The signal is sent to the D conversion 20 and branched and sent to the monitor 21 and the alarm trigger circuit 22. A parallel signal PS indicating that the generator is connected to the power system is input to the monitor 21 and the alarm / trigger circuit 22 from another control device in the power plant. The monitor 21 performs an abnormality detection operation based on signals from the torsion angle displacement meters 6a to 6c and the torsion angular velocity meter 7, and when an abnormality is detected, an alarm /
The trigger circuit 22 is operated to generate an alarm, and the trigger signal is used as a CPU operation command to A / D converter 2
Output to 0. In this case, the monitor 21 and the alarm / trigger circuit 22 are provided with an interlock function, and are brought into an operating state by being given the parallel signal PS.

In addition to the torsion measurement signal, the A / D converter 20 also outputs an electric torque signal (voltage measurement signal PT) to the generator 5 measured by a voltage measuring device and a current measuring device (not shown). And the current measurement signal CT) are input.
In the A / D converter 20, the buffer memory 23 is juxtaposed to the A / D converter 9. This buffer memory 23 is
The torsion measurement signal and the electric torque signal converted into digital signals by the A / D converter 9 are stored, and have a capacity capable of accommodating a sufficient amount of information from an assumed failure occurrence to an alarm. .. The A / D converter 20 normally converts the input measurement data into a digital signal by the A / D converter 9 and writes the digital signal in the buffer memory 23. However, the trigger signal is given from the alarm / trigger circuit 22. Then, the stored data in the buffer memory 23 is read and C
It is configured to output to the PU 10. This CPU
10 includes a display device (CRT) 11 and a hard disk 1.
2, a magnetic tape (CMT) 13, a printer 14, etc. are connected. Next, the operation of the above embodiment will be described with reference to the flowchart of FIG.

The twist angle of each shaft coupling portion 4 is measured by a twist angle displacement meter 6
Measured by a to 6c and the torsion angular velocity meter 7 (step B1), sent to the A / D converter 20, branched and sent to the monitor 21 and the alarm / trigger circuit 22.

The A / D converter 20 includes the torsion angle displacement meter 6 described above.
a to 6c and the torsion measurement signal and the electric torque signal (voltage measurement signal PT, current measurement signal CT) measured by the torsion angular velocity meter 7 are converted into digital signals and the buffer memory 2
It is written in 3 and held (step B2). In this case, the buffer memory 23 has a capacity sufficient to accommodate the amount of information from the occurrence of an expected failure to the occurrence of an alarm, and the information before that is automatically deleted.

On the other hand, the monitor 21 is brought into an operating state when a parallel signal PS indicating that the generator is connected to the electric power system is input, and the torsion measurement signal sent from the measuring instrument is converted into a waveform of a torsion angle. The signal is decomposed into mode waveforms (step B3), and the stress waveforms at the monitoring points are obtained by multiplying this by a count determined by each natural vibration type (step B4). In this monitor 21, for example, the stress waveform at the monitoring point is obtained using a simpler method than that of the CPU 10. Then, the monitor 21 compares the stress value obtained based on the torsion measurement signal with a preset threshold value (step B6).
), When the stress value reaches a level equal to or higher than the threshold value, the alarm / trigger circuit 22 is operated to issue an alarm (alarm) of the occurrence of torsional vibration, and a trigger signal as a CPU operation command is output to the A / D conversion unit 20. Yes (Step B7
).

When a trigger signal is sent from the alarm / trigger circuit 22, the A / D conversion section 20 reads the data held in the buffer memory 23 and the CPU 1
Output to 0. The CPU 10 performs abnormality processing on the basis of the data sent from the A / D conversion unit 20, decomposes the mode waveform retroactively when a failure occurs, and calculates the stress waveform at the monitoring point to obtain a series of waveform signals. Also, the data is stored in the magnetic tape 13 and displayed on the display device 11 and printed and recorded by the printer 14 (steps B8 and B9). Thus, when an alarm signal indicating the occurrence of a failure is output, the data held in the buffer memory 23 is used to decompose the mode waveform retroactively at the time of the failure occurrence and to perform the stress waveform of the monitoring point, whereby the torsional vibration It is possible to understand the actual situation.

Further, the CPU 10 analyzes the self-excited vibration due to the resonance of the electric power system and the shaft system based on the voltage measurement signal PT, the current measurement signal CT and the like converted into digital signals.
Further, the CPU 10 calculates the life consumption of the monitoring point based on the last stored data and compares it with the set value (steps B5 and B6). When the set value is exceeded, the device abnormal alarm is generated. ..

[0027]

As described above in detail, according to the present invention, the buffer memory is provided so as to always hold the torsion measurement signal for a certain period of time. It is possible to decompose the mode waveform and obtain the stress waveform at the monitoring point from the time point back to the time point of failure occurrence, and it becomes possible to understand the actual state of torsional vibration. Further, the CPU operates only from the parallel operation to the parallel disconnection, the disturbance at the time of starting and stopping does not intervene, and the measurement accuracy is improved. Therefore, there is a remarkable effect in improving the reliability of the turbine rotor.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a torsional vibration monitoring device according to an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the embodiment.

FIG. 3 is an explanatory view of the principle of torsional vibration.

FIG. 4 is a block diagram showing the configuration of a conventional torsional vibration monitoring device.

FIG. 5 is an operation explanatory view of a conventional torsional vibration monitoring device.

FIG. 6 is a waveform diagram of vibration stress.

[Explanation of symbols]

1 ... High-pressure / intermediate-pressure turbine, 2 ... Low-pressure first turbine, 3 ...
Low-pressure second turbine, 4 ... Shaft coupling part, 4a, 4b ... Shaft end part, 5 ... Generator, 6a-6c ... Torsional angular displacement meter, 7 ... Torsional angular velocity meter, 9 ... A / D converter, 10 ... CPU , 11 ... Display device, 12 ... Hard disk, 13 ... Magnetic tape, 1
4 ... Printer, 20 ... A / D converter, 21 ... Monitor, 2
2 ... Alarm / trigger circuit, 23 ... Buffer memory.

Front page continuation (72) Daisaku Hirata, Inventor Daisaku Hirata 1-1-1, Niihama, Arai-cho, Takasago, Hyogo Prefecture Mitsubishi Heavy Industries, Ltd. Takasago Plant

Claims (2)

[Claims] 1. A torsion vibration monitoring apparatus for a rotating body, wherein a torsion measuring means for measuring a torsion state of a rotating shaft and a signal measured by this means are monitored to detect an occurrence of a failure and output an alarm signal. Monitor means, buffer memory for storing the signal measured by the torsion measuring means for a certain period, and when an alarm signal is output from the monitor means, the stored information in the buffer memory is calculated retroactively from the time of alarm to the time of failure occurrence. A torsional vibration monitoring device for a rotating body, comprising: a CPU for processing and displaying a vibration waveform on a display device. 2. A monitor means for monitoring the measurement signal comprises:
2. The torsional vibration monitoring device for a rotating body according to claim 1, further comprising an interlock function which is activated when a signal indicating that the generator is connected to the power system is input.