JPS60125733A - Turbine protecting apparatus - Google Patents

Abstract

PURPOSE:To prevent malfunctioning of a turbine tripping means by a low- magnitude earthquake, by switching the input of the turbine tripping means according to the level of the values measured by seismometers disposed in the vicinity of a turbine shaft. CONSTITUTION:In case that the magnitude of an earthquake is so low that the values measured by seismometers 20a-20z are smaller than a first reference value, a vibrational relay board 23 for earthquake drives a relay 27 via a relay energizing means 26 and a manual changeover switch 28 is switched to ''automatic''. At the same time, a turbine tripping switch 25 is kept OFF by driving a relay 24 via the relay energizing means 26. In case that the measured values are greater than said first reference value, on the other hand, the manual changeover switch 28 is switched to ''manual''. Further, in case that the measured values are greater than a second reference value, the turbine tripping switch 25 is turned ON. With such an arrangement, it is enabled to prevent malfunctioning of the turbine tripping means by a low-magnitude earthquake.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is a turbine protection device, in particular, which issues an alarm when the vibration amplitude of the turbine shaft reaches an abnormal value, and furthermore, when the abnormal amplitude exceeds a certain set value. The present invention relates to a turbine protection device having a function of automatically stopping a turbine.

[Technical background of the invention]

FIG. 1 shows a block diagram of a conventional turbine protection device. The shaft vibration detectors 11a to lln are installed in the turbine bearing section and the generator bearing section, and the absolute displacement amount detected by these detectors is converted into a signal by the turbine monitoring board 12. The signal from the turbine monitoring board 12 is input to the displacement indicator 15 and displayed, and is also input to the vibration recorder 40 and recorded, and the signal is input to the vibration relay board 1.
3 is input.

The vibration relay board 13 determines the magnitude of the displacement amount based on this input signal, and sends a signal to the alarm device 14 or the turbine trip device 30.

The judgment algorithm in this vibration relay board 13 is
This will be explained using the operation diagram shown in FIG. Figure 2 shows the first
In the block diagram shown in the figure, only the portion corresponding to the vibration relay board 13 is shown as a flowchart, and the same constituent blocks as in FIG. The detected displacement amount, which is a signal from the turbine monitoring panel, is compared with three set values. That is, there are three values: an alarm value, a trip value, and a knock-up trip value. Yes - When the detected displacement amount of the bearing reaches the alarm value or more, the alarm device 14 turns ON.
This notifies the operator that an abnormality has occurred in the turbine or generator. Furthermore, if the detected displacement amount of a certain bearing reaches the trip value or more, and the detected displacement amount of any other bearing reaches the alarm value or more, the turbine trip device 30 is turned ON, and the turbine is automatically activated. Stop at. Further, when the detected displacement amount of a certain bearing reaches the backup trip value or more, the turbine trip device 30 is turned on and the turbine automatically stops, regardless of the detected change amount of other bearings.

In this way, if abnormal vibration occurs in the turbine shaft during normal operation (including startup and stoppage), in other words, the amount of whirling displacement of the turbine shaft becomes abnormal due to some reason, and the relationship between the turbine shaft and the bearings increases. If the relative displacement exceeds the set value,
The vibration detectors 11a to lln detect this abnormal whirling displacement amount as an absolute displacement, and the vibration relay board 13 takes appropriate turbine protection measures.

[Problems with background technology]

However, conventional turbine protection devices have the drawback of operating undesirably when an earthquake occurs. In other words, if the entire turbine generator including the turbine shaft and turbine bearing vibrates during an earthquake, the vibration detector will detect the absolute displacement even though the relative displacement between the turbine shaft and turbine bearing is below the set value. As a result, there was a possibility that an unnecessary turbine trip would occur.

To be more specific, if the amount of displacement obtained by adding the shaft whirling displacement meter during normal operation and the shaft whirling displacement meter due to an earthquake is less than the set value, the turbine shaft itself causes abnormal vibration. Even if the vibration detector is not installed, the vibration detector can measure not only the amount of displacement that is the sum of the amount of whirling displacement of the shaft during normal operation and the amount of whirling displacement of the shaft caused by an earthquake, but also the amount of seismic displacement at the vibration detector installation point. , the amount of displacement that also includes the amount of seismic displacement of the building and the foundation of the turbine generator is detected as the absolute displacement side.

In order to compensate for these drawbacks, the general frequency characteristics of shaft vibration detectors are designed as shown in FIG. That is, the sensitivity is 100% in the region above 13H2, which is the natural vibration frequency of the turbine, and the sensitivity decreases as the vibration frequency decreases in the region below that. Since the vibration frequency of an earthquake is usually about 2 to 1OH2, sensitivity to earthquake vibration can be kept low.

However, such a method is only an auxiliary solution. Even if the sensitivity to earthquakes is kept low,
For small-scale earthquakes in which the relative displacement between the turbine shaft and turbine bearings does not reach the trip value, the absolute displacement of one bearing is greater than the trip value, and the absolute displacement of any other bearing is If the amount reaches the alarm value or more, or if the absolute displacement bone of one bearing reaches the IJ tube value or more, an unnecessary turbine trip will be performed. It is not desirable for a plant to stop due to such a small-scale earthquake from the viewpoint of plant operation rate.

[Purpose of the invention]

Therefore, an object of the present invention is to provide a turbine protection device that does not trip the turbine due to malfunction in the event of a small earthquake in which the relative displacement between the turbine shaft and the turbine bearing does not reach the trip value. shall be.

[Summary of the invention]

A feature of the present invention is that a seismometer is integrated into the conventional turbine protection device, and the following three operations are selected according to the measured values of this seismograph, thereby eliminating unnecessary turbine trips in the case of small-scale earthquakes. The main point is to ensure that turbine trips are not carried out in the event of a large-scale earthquake.

1. If the vibration caused by the earthquake is less than the vibration that causes the turbine trip to malfunction, the turbine trip operation is automatically performed based on the displacement amount of the shaft vibration detector, similar to the operation of the conventional turbine protection device.

2. If the vibration caused by the earthquake is greater than the vibration that causes a turbine trip to malfunction, but does not reach the level that requires an immediate turbine trip, switch the turbine (IJ) knob operation to manual and Leave it to appropriate judgment.

3. If the vibration caused by the earthquake reaches a level that requires an immediate turbine trip, immediately perform a turbine IJ trip, regardless of whether the turbine trip operation is automatic or manual.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail based on illustrated embodiments. FIG. 4 is an overall view of a nuclear power plant having a device according to the invention. A turbine building 5 is built adjacent to a reactor building 4 that houses a nuclear reactor 6. A turbine generator foundation 7 is provided within the turbine building 5, and the turbine generator 3 is installed on this. The turbine shaft 1 has a turbine bearing 21
7j, and a shaft vibration detector is attached to the turbine bearing 2. A casing 5■ covers these.

Seismometers 20a, 20 are installed on the turbine generator foundation 7.
1).

20c, 20(1, zO2 is added. An enlarged view of the partial part in FIG. 4 is shown in FIG. 5. Turbine shaft 1
The vibrations are extracted as vibrations of a vibration detector 8 attached to the turbine bearing 2 via a spring 9, and detected by a vibration detector 11.

FIG. 6 shows a block diagram of the configuration of an embodiment of the present invention. The signals of the shaft vibration detectors 11a to lln are sent to the turbine monitoring panel 12.
It is input to the vibration relay board 13 via.

The output of the vibration relay board 13 is connected to a relay 17 via a relay energizing device 16. This relay 17 drives an automatic turbine trip switch 18 connected to a power source 19 to control the turbine trip device N30. The output of the turbine monitoring panel 12 is also input to the vibration recorder 40 and the displacement table 15, and is recorded and displayed. The vibration relay board 13 is directly connected to the alarm device 14 and issues an alarm when necessary.

Earthquake detectors 120a-20 installed around the turbine generator
The output of Z is input to the seismic vibration relay board 23.

One of the outputs of the seismic vibration relay board 23 is connected to a relay 27 via a relay energizing device 26, and the other output is connected to a relay 24 via a relay energizing device 32.
, the relay 27 drives the manual changeover switch 28 connected to the power source 29 to automatically switch (on the turbine trip device 30 side)
Alternatively, switch to manual (manual switching signal alarm 21 side). When switched to manual mode, the power source 29 is further connected to the turbine trip device 3θ via the manual turbine trip switch 22. Relay 24 is power supply 31
Seismic automatic turbine trip switch 25 connected to
to control the turbine trip device w30.

Next, the operation of this embodiment will be explained using the operation explanatory diagrams of FIG. 6 and FIG. Figure 7 shows the vibration relay board 13 and earthquake vibration relay board 23 in the block diagram of Figure 6.
, and only the parts connected to each relay are shown as a flowchart, and the same reference numerals are used for the same constituent blocks as in Fig. 6, and the explanation thereof will be omitted.

The outputs from the seismometers 20a to 20Z are input to the seismic vibration relay board 23, and the measured values are compared with the set value α.In order to increase the reliability of the measured values, the following logic is used. It is preferable to take a structure. That is, as shown in Figure 8g6, first, the H1 measurement value is set to the set value α for each tlltWil.
1, then perform a logical sum for each pair of seismometers, then perform a logical product for each pair of logical sums, and finally calculate a logical sum for these logical products. It is preferable to have a structure that takes . A flowchart of this algorithm is shown in FIG.

First, the seismic vibration relay board 23 sets the measured values by the seismometers 20a to 20H to the set value α according to the above-mentioned algorithm.
(The set value α is a vibration value that may cause the turbine monitoring panel 12 to instruct the turbine to trip due to the absolute displacement of the shaft even though the relative displacement between the turbine shaft and the bearing is within the allowable value.) .) Explain the operation when it is determined that the following is the case, that is, when an earthquake does not occur normally, or when it does occur (even if it does occur, it is a small earthquake whose scale is less than the set price α) In this case, the seismic vibration relay board 23 drives the relay 27 via the relay energizing device 26 and automatically switches the manual changeover switch 28 to
I! IJ (turbine trip device 30 side), and also drives the 1 relay 24 via the relay energizing device ffi', 32 to keep the earthquake automatic turbine trip switch 25 in the OFF state. The operation under such conditions is similar to that of the turbine protection device according to the prior art.
Ii Le. That is, the amount of displacement detected by the plurality of shaft vibration detectors 11a to 11n installed in the turbine bearing section and the generator bearing section is converted into a signal by the turbine monitoring panel 12, and one of these signals is used as a displacement display. The other signal, which is input to the total 15 and vibration recorder 40 and continuously displayed and recorded for each bearing, is input to the vibration relay board 13, where the amount of displacement is determined. When the displacement amount of a certain bearing reaches the alarm value or more, the visual information device P14 is activated to notify the operator that an abnormality has occurred in the turbine bearing or the generator. In addition, when the displacement of one bearing reaches a trip value (set to a value larger than the alarm value),
And if the displacement amount of any other bearing reaches the alarm value or more, or the displacement amount of one bearing is set as a backup trip value (set separately from the alarm value and trip value).
If the above condition is reached, the relay 17 is activated via the relay energizing device 16, and the automatic turbine trip switch 18 is turned on. Since the manual changeover switch has already been switched to automatic (turbine trip device 3θ side), the turbine trip device 30 is turned on and the turbine is automatically stopped.

Next, when the seismic vibration relay board 23 determines that the measured values by the seismometers 201L to 20z are equal to or higher than the set value α according to the above-mentioned algorithm, t), that is, when an earthquake of a magnitude exceeding the set value α occurs. Explain the operation of.

In this case, the seismic vibration relay board 23 drives the relay 27 via the relay energizing device 26, and the manual changeover switch 2
8 to manual (manual switching signal alarm 21 side), and also drives the relay 24 via the relay energizing device 32 to turn off the earthquake automatic turbine trip switch 25.
Keep it in F condition. When the manual changeover switch 28 is changed to manual, the manual changeover signal alarm 21 is activated, notifying the operator that the turbine trip operation has been changed from automatic to manual. The operator can turn on the turbine trip device 30 and stop the turbine by turning on the manual turbine trip switch 22 as needed.

Finally, the seismic vibration relay board 23 determines, according to the above-mentioned algorithm, that the measured values by the seismometers 20a to 20z are set to a set value β (the set value β is a vibration that causes the relative displacement between the turbine shaft and the bearing to exceed the allowable value). β) α in the vibration value of a large-scale earthquake that would give. ) or more, that is, when a large-scale earthquake exceeding the set value β occurs, the operation will be explained.

In this case, the earthquake vibration relay board 23 drives the relay U via the relay energizing device a32, and turns on the earthquake automatic turbine trip switch 25. This turns the turbine trip operation 30 ON and the turbine automatically stops.

〔Effect of the invention〕

As described above, according to the present invention, even if the absolute displacement between the turbine shaft and the bearing exceeds the set value for performing a turbine trip when the entire turbine equipment is shaken due to the terrain etc. If the displacement does not exceed the set value for performing a turbine trip, immediately perform a turbine trip and change the turbine trip operation from automatic to manual.
By leaving this to the operator's appropriate judgment, unnecessary shutdowns of the turbine can be prevented and the plant's operating rate can be significantly improved.

Also, the relative displacement between the turbine shaft and the bearing causes a turbine trip.7. (In the event of a large-scale earthquake that exceeds the set value, the automatic turbine trip switch for ground 73 allows the turbine to trip automatically due to its own gravity, which also improves the safety of the plant.

[Brief explanation of drawings]

Figure 1 shows the configuration block (9) of a turbine protection system according to the prior art, Figure 2 is an explanatory diagram of the operation of the turbine protection system according to the prior art, and Figure 3 shows a typical shaft vibration detector. Frequency characteristic diagram, fI: Figure 44 is an overall view of a nuclear power plant having a device according to the present invention, Figure 5 is an enlarged view of part A in Figure 4, and Figure 6 is a structural block diagram of an embodiment of the present invention. FIG. 7 is an explanatory diagram of the operation of an embodiment of the present invention. 1...Turbine shaft, 2...Turbine bearing, 3...
Turbine starter pw machine, 4... Reactor building, 5... Turbine building, 6... Nuclear reactor, 7... Turbine starter base stand, 8... Shaft vibration detector, 9... ··spring,
Ila~lln... Shaft vibration detector, 12... Turpin monitoring board, 13... Photographing relay board, 14... Alarm device, 15... Displacement sensor, 16, 26. 32...Relay energizing device, 17, 24, 27...
・Relay, 18... automatic turbine trip switch,
19,29.31...Power supply, 20a-202...Seismometer, 21...Manual switching signal 'alarm', 22...
Manual turbine trip switch, 23... Earthquake vibration relay board, 25 River earthquake automatic turbine trip switch, 28... Manual changeover switch, 3o... Turbine trip device, = 40... Vibration recorder, 51...Casing. Applicant's agent Kiyokon Inomata 3

Claims (1)

[Claims] 1. A shaft vibration detector that detects the amount of displacement between the turbine shaft and the bearing, and a vibration relay that inputs the amount of displacement from the shaft vibration detector and determines whether or not to perform a turbine trip. A turbine protection device comprising a panel and a turbine trip device that operates to stop the turbine in response to an input signal, a seismometer installed around the turbine shaft, and inputting measured values from the seismometer. and an earthquake vibration relay board that switches the input of the turbine trip device to one of the following three depending on the magnitude of the measured value. (1) If the measured value is less than the first set value, input the output signal of the vibration relay board to the turbine trip device. (2) If the measured value is greater than or equal to the first set value and less than the second set value, a manual control signal is input to the turbine trip device. (3) If the measured value is equal to or greater than the second set value, a signal for performing turbine IJ tripping is unconditionally input to the turbine trip device.