JPS6111406A - Oscillation supervisory equipment for turbine - Google Patents

Abstract

PURPOSE:To prevent an unexpected tripping caused by earthquake so as to supply electric power stable, by setting filters and timers which are suitable for the characteristics, in each of a starting circuit and a load-operation circuit, in an oscillation supervisory equipment for a turbine. CONSTITUTION:A parallel circuit consisting of an earthquake filter 23 which cuts off the earthquake waves of under the dominant frequency, and a low frequency cut filter 24 which passes the frequency component of more than the lowest characteristic frequency of a turbo-generator shafting, is set between an oscillation detector 12 and an integrator 13, in an oscillation supervisory equipment for a turbine. Another parallel circuit consisting of two timers 25, 26 which prevent trip signals for a given period of time, correspondently with the characteristics of the said filters 23, 24, is set between a comparing deciding device 15 and a trip device 17, and the combination among two pairs of the filter and the timer, is mutually switched by operating switching-units 29, 30 according to external signals 27 determined by the operating condition of the turbo-generator.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a vibration monitoring device that measures and monitors the shaft vibration of high-speed rotating machines such as steam turbines and generators. This invention relates to a turbine vibration monitoring device that prevents trips and the like.

[Technical background of the invention and problems]

The most important thing in the operation of high-speed rotating machines such as steam turbines used in power generation plants and the like is to suppress shaft vibration to an appropriate level under all operating conditions.

By the way, signs of excessive shaft vibration often appear when the turbine is started or when the load changes, and photographing is one of the many common operational monitoring items that requires particularly strict monitoring.

In addition, as the capacity of nuclear power plants increases,
Because it plays an important role as a base load in Japan, there is an even stronger need to improve the reliability of rotating machinery such as turbines and generators, which are the main equipment. Therefore, measurement of vibration, which is an indicator of the reliability of rotating machinery, is extremely important, and the vibration measurement used there must also be highly reliable. Similarly, vibration monitoring equipment that uses vibration signals as sensors must also be highly reliable; for example, if a steam turbine were to come to an emergency stop due to a vibration meter malfunction, it would cause difficulties in social life. Therefore, sufficient care must be taken when configuring the vibration monitoring device.

From this point of view, steam turbine generators used in thermal power plants and nuclear power plants have
Constantly monitors shaft vibrations of turbine rotors and generator rotors,
When the vibration amplitude value exceeds a certain value, an alarm will be issued and the operation will be stopped.
An automatic alarm system that notifies the user of an abnormality, or an automatic system that automatically trips (stops operation) by suddenly closing the steam turbine inlet valve when the vibration amplitude value increases further and exceeds a set value. A trip device is installed for safety reasons.

FIG. 1 is a diagram showing general vibration measurement points of a turbine generator, in which a high-pressure turbine rotor 1, a low-pressure turbine rotor 2, and a generator rotor 3 are flange-coupled as a single shaft system, and each A portion of the rotor body 4 is supported by a bearing 5 at the front and rear journal portions 4 .

By the way, a vibration meter 6 is usually attached to the bearing 5 as shown in FIG. That is, the outer cylinder 9 of the vibration meter 6 is fixed to a bearing stand 8 installed on the base 7-L. A detection rod 11 is provided concentrically within the outer cylinder 9 and is biased into the bearing 5 by a spring 10, and the tip of the detection rod 11 is pressed against the journal portion 4.
A detector 12 is attached to the proximal end of 1.

Therefore, when the journal part 4 vibrates, the vibration is transmitted to the detector 12 by the detection rod 11 that is in contact with it. In the contact-type vibrometer 6 as described above, the detector 12 is usually composed of a velocity meter or an accelerometer, so that the absolute vibration of the journal 4 can be detected as velocity or acceleration via the detection rod 11. can. Therefore, the above vibration ffl
The output from 6 is integrated by an integrator 13 and converted into a displacement signal. The model of the vibration meter 16 is bearing stand 8.
There are also non-contact types that use a displacement meter that can directly detect changes in the relative displacement of the journal part 4. By the way, the displacement signal is rectified by the rectifier 14 and is input to the comparison/judgment device 15 after being changed into a vibration amplitude change which is the absolute value of the displacement.

The comparison/judgment device 15 has a built-in arithmetic circuit that compares the amplitude signal with a predetermined vibration limit value, that is, an alarm value or a stop value, and when the vibration amplitude of the journal section 4 exceeds the alarm value, , outputs an alarm signal to the alarm device 16, and when the amplitude further increases and exceeds the stop value, outputs a stop signal to the trip device 17. Therefore, the alarm device Ff 16 or the trip device @17 is the comparison judgment device N15, respectively.
Depending on the output, an alarm is issued to notify the operator of the abnormality, or the turbine generator is tripped.

The comparison/judgment device 15 is provided corresponding to the vibration meter 6 mounted on each bearing 5, and the output signal of each comparison/judgment device 15 is transmitted to the common alarm device 1 as shown in FIG.
6 and a trip device @17, forming one vibration monitoring device.

Such a vibration monitoring device for a turbine protects the turbine generator from vibrations caused by internal factors of the turbine generator itself, such as rotor unbalance, rubbing, oil whip, and steam whirl. The main purpose is to improve safety. However, since the vibration meter 6 is installed as shown in Fig. 2 and generates absolute vibration R1, it cannot detect the vibration not only when the journal section 4 vibrates, but also when the whole body including the bearing stand 8 vibrates. It will be sensed. Although such a phenomenon does not occur unless a considerably large external force acts on it, there are cases such as earthquakes where it cannot be ignored.

By the way, the bearing stand 8 is generally fixed to a foundation stand 7, as shown in FIG. 4, and the foundation stand 7 is installed on a mat 18, and the mat 18 is further placed on the ground 19. ing. Therefore, when an earthquake occurs, the vibration is transmitted from the ground 19 to the mat 18, and further to the foundation 7.
The bearing stand 8 and the journal portion 4 are vibrated through the vibration.

When this vibration system consisting of the turbine/generator and the turbine foundation is modeled, as shown in Fig. 5, the total quality m of the high pressure turbine rotor 1, low pressure turbine rotor 2, and generator rotor 3 in Fig. 1 is A corresponding mass 20, a spring 21 corresponding to the rigidity of the turbine/generator base 7,
It can be replaced with a general spring mass system consisting of a damper 22 representing a damping term. If the mass corresponding to the total mass of the rotor is the spring constant of the M1 spring 21, and the damping coefficient of the 1 damper 22 is D, then the external force applied to the mat 18 is X = A□S! The response of the turbine/generator to n(1)j is the input amplitude A.

The ratio of the response amplitude A2 to the response amplitude A2 is expressed as follows.

Here, η−〇θ)o: If the foundation system including the turbine generator has a small natural frequency damping, then I! If the frequency component of the I seismic wave and the natural frequency of the foundation system match, = 8
- In other words, in the case of η-1, the vibration of the turbine generator placed on the foundation becomes large. The excitation force is
The excitation force may reach 2 to 5 times the excitation force on the mat 1B, although it varies depending on the vibration characteristics of the mat 1B. In addition, even if the entire bearing base 8 vibrates, the vibration shield 6 is designed to sense the vibration displacement, so even if an external force such as an earthquake acts on the foundation base, the amount of vibration displacement will be reduced. Stop (When reaching 1 h, a stop signal is also sent to the trip device 17, and the turbine trips.

The relationship between vibration displacement and acceleration is expressed by the following equation.

δ−αX9800/(2πf) ・・・・・・(2)
Here, δ: Vibration displacement α: Acceleration f: Frequency As can be seen from this equation, even if the acceleration is small, a large displacement will occur if the frequency is low. For example, if the acceleration is 0.0 G and the frequency is 5 Hz, the displacement is 0.5
m. The above j; sea urchin is transmitted through the foundation J:
The seismic waves are amplified and input to the bearing stand 7. For example, if the vibration response magnification is 2, the mat 18 is 0.0
When excited by an earthquake motion of 25G, the bearing stand 7 is 0.05
G is applied, and the displacement is amplified to 0.5111n. Therefore, if this exceeds the stop value, the comparison/judgment device 15 outputs a stop signal and the steam turbine trips. Seismic waves include many frequencies, and as can be seen from equation (1), the amplitude response magnification differs depending on each frequency, so such a simple calculation is not sufficient, but the results of this study are at least 0.0
This indicates the possibility that even if a small earthquake of 25 GPi occurs, the steam turbine will trip and power transmission from the plant will be halted.

The above is a case in which the vibration meter 6 directly senses seismic waves or amplified seismic waves via the bearing pedestal 8 and causes a trip. A temporary large amplitude induced as a result of a forced external displacement between the rotor journal 4 may reach a trip value.

The latter phenomenon has been revealed through recent case analysis, and even if the former is completely addressed, there remains the possibility of an inadvertent turbine trip due to an earthquake. On the other hand, if the large-capacity turbines and generators responsible for the base load trip unnecessarily, the impact on the power system will be extremely large, leading to wide-area power outages and causing social chaos.

Therefore, there has been a need for a turbine vibration monitoring device that can accurately deal with shaft vibration phenomena caused by failure, even in the event of a failure.

(Object of the Invention) In view of the above points, the present invention prevents unnecessary turbine trips due to the occurrence of an earthquake, and can minimize the chances of turbine trips.J:
The purpose of the present invention is to obtain a turbine vibration monitoring device that has the following characteristics.

[Summary of the invention]

The present invention includes an oscillation detection device that continuously detects vibrations of a rotating shaft, and a vibration signal detected by the vibration detection device that is compared with a predetermined vibration limit value. In a turbine vibration monitoring device having a comparison judgment device that outputs a trip signal to automatically stop the unit when the vibration exceeds the limit, and an automatic trip device that inputs the trip signal and automatically stops the unit,
The vibration detection circuit is composed of two systems: a startup circuit that is used when the rotation of the turbine/generator increases, such as during startup, and a load operation circuit that is mainly used after the system is connected to the system. The operation circuit has a filter that cuts a specific frequency range of the vibration signal detected by the vibration detection device, and the startup circuit and the load operation circuit are provided between the comparison judgment device and the automatic trip device. A timer that stops the trip signal for a certain period of time is determined based on the characteristics of each of the circuits, and a timer that stops the trip signal for a certain period of time is interposed in each circuit, and the combination of these two sets of circuits and timers is It is characterized by being able to switch, which prevents inadvertent tripping due to increased shaft vibration due to earthquake motion, and prevents the turbine/generator from tripping due to a small earthquake. This is what I did.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 6 to 20. In the figure, the same parts as those of the conventional device are given the same reference numerals, and detailed explanation thereof will be omitted.

FIG. 6 is a schematic system diagram showing an embodiment of the turbine vibration monitoring device of the present invention, in which a filter (earthquake filter) is provided between the detector 12 and the integrator 13 to cut frequencies below the dominant frequency component of seismic waves. 23 and a filter (low frequency cut filter) 24 that passes frequency components equal to or higher than the lowest order characteristic signal number of the turbine/generator shaft system. In addition, two timers 25 and 2 are set to stop inputting the trip signal to the trip device for a certain period of time corresponding to the characteristics of the two filters 23 and 24.
6 parallel circuits are set up (7) 2□1.
Hui-o, iV-o116iq@1. −′2□bin・
A switching device 29 is activated by a switching signal from an external signal detector 28 that detects an external signal 27 determined from the operating conditions of the generator.
and 3o, and are configured to be used selectively. Therefore, when the turbine is started, the earthquake filter 23 and the timer 25 are inserted into the vibration detection circuit, and when the turbine is operating at the rated rotation speed, the low frequency cut filter 24 and the timer 26 are inserted into the vibration detection circuit. Therefore, the seismic wave area is so as to eliminate the response vibration of the rotor.

That is, a characteristic generally required of a vibration monitoring device is to accurately detect and monitor vibration signals in all frequency ranges that are as close to the actual vibration waveform as possible. Therefore, if this characteristic is directly realized in a vibration monitoring device,
As mentioned above, in the event of an earthquake, the detector itself directly detects the seismic waves, or the large vibration amplitude of the rotor shaft system that occurs in response to the seismic waves is detected, leading to a large vibration l-rip. become.

Therefore, in the present invention, a timer 25 such as an earthquake filter 23 or a timer 26 such as a low frequency cut filter 24 is selectively inserted into the vibration detection circuit to remove seismic waves or the response vibration of the rotor caused by the seismic waves, and thereby prevent tripping. This is to prevent the device from operating inadvertently.

However, as a vibration monitoring device, the installation of such additional elements must not hinder the monitoring of abnormal vibrations that indicate an abnormality from the machine itself, and the characteristics of these additional elements, i.e. the frequency below which The question is how long should it be removed. In order to determine these, it is necessary to know not only the characteristics of seismic waves but also the nature of vibrations that appear in rotating machines in general or in response to seismic waves, especially their frequency components.

Among these, seismic waves are determined by the structure of the ground where the turbine/generator is installed and the location of the seismic wave (depth, distance l1lIt).
The seismic waves experienced to date are generally in the frequency range of 0 to 20H2, as shown in Figure 7, and within this, the low frequency component of about 3 to 8H2 is 0). . It is generally recognized that it is overdue.

On the other hand, most of the vibrations caused by the machines themselves that occur in turbines and generators are vibrations and self-excited vibrations caused by unbalance m generated in the rotor for some reason. The former is mainly composed of rotation synchronous components with the same frequency as the machine's operating speed, and for thermal turbines, the frequency is 50Hz, 6
0f-1z, and since nuclear power turbines usually employ a four-pole machine, they are 25)-1z and 301-(z).

This vibration is an important factor in vibration monitoring because mechanical abnormalities such as panel scattering, rotor bending, changes in alignment, and contact with stationary parts are sensitively manifested. In addition, a typical example of self-excited vibration is the oil whip phenomenon caused by the oil film characteristics of a bearing.Once it occurs, it persists, and vibrations with severe amplitude can sometimes lead to damage to the bearing or destruction of the shaft itself. There is. FIG. 8 is a diagram showing a frequency analysis of vibrations when this development occurs, and has the property of vibrating at the lowest critical speed (C) of this shaft system. However, the lowest critical speed of turbines and generators currently in use is around 10 Hl for nuclear turbines and 20+-I2 or more for thermal turbines, so they will oscillate at the above frequencies. .

On the other hand, elucidating the behavior of the vertical axis during an earthquake requires highly accurate sicomilation tests, as it is extremely difficult to perform measurements using actual equipment. Figure 9 is an example of such an analysis result, and shows the response waveform d, which is the theoretically determined vibration response of the rotor when seismic waves are input from the direction perpendicular to the shaft, and the vertical axis is the journal. It represents the relative displacement between the portion 4 and the bearing 5, that is, the vibration value of the rotor, and the horizontal axis represents time. Moreover, FIG. 10 shows this response waveform (10 frequency analysis values).

This figure shows that during an earthquake, the rotational synchronous component, which is unbalanced vibration during steady state, is 0). It can be seen that a low frequency component ω1, which has a much larger vibration and is close to the Chuetsu frequency ω of the earthquake, and a component θ)2 that responds to the natural frequency ω of the shaft appear. and generally 011ωo, (i)210). The relationship holds true.

From the above analysis, it can be said that the frequency that should be constantly monitored as a turbine/generator is equal to or higher than the TFI low-order natural frequency of the target rotor system.

That is, in FIG. 8, ω is the self-excited photographing frequency and ω is the rotation period component. , and furthermore, 1-
If the earthquake response vibration frequency 0)2)θ) can be monitored, vibration monitoring during steady operation will be 1 minute.

To explain this in Figure 11, the shaded area X is the area that needs to be constantly monitored as a shaft vibration meter, and the solid line f depicts the strength of each frequency generally included in seismic waves. As is clear from this figure, there are some measures to eliminate the low-frequency component of shaft vibration that occurs during an earthquake without disturbing the vibration caused by a mechanical earthquake. is the lowest natural frequency ω of the rotor system that is <7 with the λ1 elephant. It is concluded that the best filter (low frequency cut filter) 24 is the one that removes frequencies below the frequency as close as possible to
Ru.

However, if the filter characteristics are set in this way, when the operating speed is in the frequency range removed by the filter when the turbine generator is rotating, such as at startup,
This results in so-called idle operation where the vibration of the rotor cannot be detected. Particularly in a machine where the lowest natural frequency of the rotor system is high, such as a steam turbine of a thermal power plant 1-, this condition continues up to a high rotational speed, which is not desirable.

This contradictory request is fM>Nsa1! One way to do this is to use a filter that cuts the shaded area Y (11) shown in Figure 11, that is, a filter (J, 1111 seismic filter) 23 shown in Figure 12 that has the same sensitivity. That's true.

The above-mentioned embodiment of the present invention was constructed taking into consideration the above two points, and by doing so, the influence of seismic waves can be minimized or reduced.
And the vibration energy increases (60 old) m (10H7)
At rotation speeds above around 4T, it is possible to see the axial vibration φ)j value almost completely.

In this case, it is clear from Fig. 12 that the monitoring of shaft vibration becomes incomplete below 600 rpm, but this is due to the fact that the seismic filter 23 is installed.
This is because it satisfies the minimum requirements for monitoring shaft vibration when the rotation of the turbine/generator increases. That is,
In the extremely low rotational speed range of less than 600 rpm (10l-lz), the vibration energy is extremely small, and even if vibration cannot be directly monitored, it can be used to check startup operations, etc. This is the reason.

In other words, if we assume that earthquake countermeasures are taken for all operating conditions of the turbine/generator, then when the turbine/generator rotates, By using a low frequency cut filter 24 (a filter that cuts areas other than the X region in Fig. 11) during zero load operation after merging, Just in case, we can achieve that goal.

However, although the seismic filter 23 can cut out the main components of seismic motion, it allows higher frequency components to pass through as is, so it is possible that the shaft system will resonate with those components, resulting in large vibrations. , the lowest natural frequency component of the shaft system excited by the seismic force using the low frequency cut filter 24. has been removed.

Therefore, in the present invention, in order to eliminate the inconveniences such as the series of -1, the comparison judgment device 15 and the devices 1 to 1 to N
17, during a certain period of time corresponding to the characteristics of the seismic filter 23 and the low frequency cut filter 24, respectively. Limers 25, 26, which operate automatically, are interposed in parallel.

'l 47 The above embodiment completely prevents unnecessary stoppage due to the 1 liter N charge during stable operation of the turbine/generator. This is based on the concept of allowing the turbine to automatically stop in the event of a large earthquake or when the response vibration of the shaft system is large, and the timer 25 corresponding to the earthquake filter 23 is connected to the trip circuit. The commonly used timer for preventing false beliefs 8 and 11 is set to a time limit of 2 seconds or less, while the timer 26 corresponding to the low frequency cut filter 24 responds to seismic waves. It is set to about 30 seconds based on the duration of shaft vibration, that is, the duration of the earthquake itself.

However, if the vibration signal that has passed through the filter exceeds the vibration large trip (IC1) and the duration of IC1 is short, the turbine/generator will not trip, making the turbine/generator unnecessary. Yes, operation stoppage is prevented.

That is, only when the vibration signal continues for more than the set time of the timer 25 when the turbine is started (passes through the vibration filter 23), a lip signal to 1 is input to the trip device 17, and the turbine is stopped. On the other hand, when the startup of the turbine is completed and the load operation state is reached, the low frequency cut filter 271 and the timer 26 are inserted into the vibration detection circuit by the cutter 29 and 30, and from then on, large vibrations that have passed through the low frequency cut filter 24 are inserted into the vibration detection circuit. Only when the signal continues for more than the set time of the timer 26, a trip signal is input to the trip device 17 and the turbine is stopped.

Figure 13 shows an embodiment of the present invention. 1 is a schematic system diagram in which the seismic filter 23 in () in the first embodiment is deleted.

In this case, the vibration detection circuit is switched from the circuit without a filter to the circuit with the low frequency cut filter 24 when the turbine starts up and shifts to load operation.
9, 3 (switched by the operation of 1. Looking at this from the effect of the filter, as shown in Fig. 14 1J, the state a without a filter is switched to the low frequency cut state [), and one solution is shown in Fig. 6. In the case of the first embodiment, the state C is switched from the seismic wave ht1 to the low frequency cut state Qjtb. L I'm angry, I'm angry.
In the case of
Since only the seismic wave response component 0〉1 and J: and its high frequency J: can be cut, the influence of the earthquake can be removed. However, in these cases, while the detector 6 detects the imaging spectrum as shown in FIG.
As shown in Figure 5, it can be seen that it is extremely effective.

FIG. 16 shows still another embodiment of the present invention, in which a filter (bandpass filter) 31 is provided in place of the low frequency cut filter 24 in FIG. 6, which passes only the rated rotational speed component of the shaft system. , since the timer 32 corresponding to the bandpass filter 31 acts in conjunction with the trip delay command for the normal vibration appearing as the rated frequency component, it is not preferable to set it for a long time.
~6 seconds. The point (11!) is the same as the embodiment shown in FIG.

Therefore, the input to this comparison judgment equipment 15 is the 17th
As shown in the figure, earthquake countermeasures are considered to be more effective than 4T. By the way, the drawback in this case is that the natural vibration component is 0 for the self-excited vibration shown in FIG. 8 that may occur during normal operation. However, large vibrations that can lead to machine destruction are
Eventually the rated rotational speed component will be 0).

Due to the fact that this is accompanied by an increase in risk, the problem is only to the extent that there is some sensitivity to danger prediction.

Furthermore, during the set time of the timer 32, the seismic waves are sequentially amplified to the ground 19, the mat 18, the foundation 7, the bearing pedestal 8, and the bearing 5, and finally the turbine/lightning VsI4111
It is determined by taking into account the duration of this phenomenon, taking into account that it may flatten due to a phenomenon of large axis amplitude.

Generally speaking, the duration of the main earthquake motion is expressed by the following equation.

+(1(+(d0)-〇, 3XM-1,2...
(3) Here, -r-o: If! + Continuation of the main motion of the earthquake between n and v M: Earthquake's magnitude (magnitude) - Figure 18 shows this equation diagrammatically, and shows that, for example, at magnitude 7, a strong earthquake continues for about 10 seconds. It shows.

By the way, when a seismic wave enters the turbine/generator foundation 7, the frequency of the seismic wave resonates with the eigenvalue of the turbine/generator foundation, and the seismic wave components near this frequency are amplified. Ru. The degree of this amplification depends on the frequency components of the seismic waves and the characteristics of the turbine/generator foundation, but is generally about three times as large. In addition, turbine/power generation II M li! i! The seismic waves amplified by the stand pass through the bearing stand, the l1llt bearing, the bearing oil film, and then 1.
It is amplified by 5 to 28 times and ultimately enters the turbine/generator rotor at a magnitude 4.5 to 6 times the magnitude of the earthquake input to the turbine/generator foundation 7. .

However, the strong seismic waves coming to the turbine/generator 1]-ta are frequency components that resonate with the turbine/generator foundation, bearing pedestal, etc., and the duration of a strong earthquake with this frequency component is 5 to 5. It is shorter at 6 seconds. Furthermore, this amplified seismic wave causes a shaft vibration phenomenon in the turbine/generator rotor when the seismic wave has a frequency component close to the critical speed of the turbine/generator rotor. Normally, plants that are prone to earthquake problems are nuclear power turbine plants that have a four-pole rotor and have critical speeds around 151-12. Although this frequency component is not the main component of the seismic wave, it is a constituent component, and it is amplified because it is within the range that exists as an eigenvalue of the turbine/generator foundation, but the duration of the amplification is at most 1 ~ It is 5 seconds. That is, lI! ! Earthquake/1-shi and j: is a turbine.
It can be said that the time period during which the shaft vibration phenomenon persists when the generator rotor is affected is generally 4 to 5 seconds.

By setting the time limit timer 32 having a 9-time period as described in 1 in the trip signal circuit, the rated frequency component is generated only during the period of the shaft vibration worker phenomenon, even if the earthquake occurs 4l-nY. Mechanical tripping is avoided even if the But b II! Once I ff is finished, unless there is an abnormality in the turbine/power generation unit 11 or other equipment, the shaft vibration phenomenon will converge in an extremely short time, and the engine will continue to operate normally thereafter. The Rukoto. On the other hand, if an abnormality occurs inside the equipment due to an earthquake, the shaft vibration phenomenon will continue even after the earthquake has subsided, so a unit trip signal will be sent to the automatic trip device 17, and the turbine/generator will stop. , the protection function is not impaired by the installation of the timer 32.

On the other hand, the low frequency cut filter 2 in FIG. 6 or 13
The set time of the timer 26 corresponding to 4 is determined based on the duration of the earthquake as described above, and the value t depends on the vibration characteristics of the structure shown in FIG. 4 as shown in FIG.

Specifically, the low frequency cut filter 24 shown in FIG.
According to the characteristics of However, for a general foundation structure, it is necessary to consider about 5 to 15 seconds for fire crab units and about 10 to 30 seconds for m (child units).

At this point, please note 4: Although the time set in this way is good during an earthquake, it will delay the trip by this amount during normal operation.
It's definitely not a good thing.

FIG. 19 shows an example of an operating method for overcoming such drawbacks. During normal operation, the worker trip value arrival signal from the comparison/judgment device 15 is sent to the alarm device 16.
to the normal worker alarm value (ANN) as shown in Figure 20.
-1) The idea is that the operator is notified as a trip warning (ANN-2>) that is higher than the previous one, and the trip device 17 is manually tripped at the operator's discretion. Alternatively, the large vibrations excited by this are first attenuated by the low frequency cut filter 24 and blocked by the timer 26, but if the shaking continues even after the earthquake has passed, an automatic trip by the trip device 17 is activated. Become.

If such a 4T operation method is adopted, the automatic trip function during normal operation can serve as a backup against the delay of manual trip due to operation 0, which is extremely rational.

Switching between the starting circuit and the load operation circuit in FIGS. 6, 13, and 16 is performed by detecting an external signal 27 according to the operating conditions of the turbine/generator with an external signal detector 28.
This is done by operating the switches 29 and 30 simultaneously, and if the timing is appropriately selected depending on the characteristics of the filter used and the timer associated with it, a very rational monitoring device can be achieved.

For example, in the configuration shown in Figure 13, the low frequency cut filter 2
4 is used, so switching is possible at any time as long as the rotational speed of the turbine/generator passes the lowest natural frequency of the shaft system. Therefore, as the external signal 27, the lowest natural frequency from the rotation frequency meter (not shown) is determined depending on the concept of the operational state in which the turbine/generator has reached stable operation, in which tripping is not desired even in the event of an earthquake. Load signal or rated speed reaching signal, or system breaker (not shown)
You can use the system joining signal etc.

By the way, the vibration limit value for normal operation in the comparison judgment device is determined by the vibration limit value for steam turbines and power generation against increased vibrations caused by internal factors such as unbalanced vibrations, rubbing, oil whip, and steam whirl in the rotor system, as described above. In order to protect the machine and to detect as early as possible any tendency towards normal vibration levels, the strength of the bearings that support the rotor system is set much lower than the strength limit. It is.

In other words, the risk of large vibrations generally lies in the contact between rotating parts and stationary parts, and the tendency for this to become dissipative due to the thermal surface phenomenon of the rotor that occurs as a result of local heating of the rotor. The vibration limit value is set as low as t-J.

On the other hand, the response of the rotor system during an earthquake corresponds to the case where the vibration system is given forced external displacement from its stable position as shown in Figure 5, but the vibration characteristics of the turbine/generator shaft system due to normal design are similar to those shown in Figure 5. It has been clarified that the rotor system, bearing, and bearing stand move as one because it has extremely high rigidity. In such a case, it is sufficient to take measures on the vibration n1 side so that the vibration meter does not detect the seismic motion, but if the seismic motion appears as it is as a relative image between the rotor and the bearing, the fifth
This is a case in which the natural frequency of the vibration 11 shown in the figure is relatively close to the predominant frequency of an earthquake, which is said to be 8 to 10H7, and in this case, the rotor experiences a superposition of seismic waves and a frequency corresponding to the natural frequency, albeit temporarily. This causes large vibrations that exceed the normal operation limit trip value. Examples of this can be seen in large-capacity 4-pole steam turbines/generators with a rated rotation speed of 1500 or 1800 rpm.
Since it is a unit of m, it often has a natural frequency in the vicinity of 12 to 151-1z, and therefore is easily affected by earthquakes.

However, although the amplitude of large vibrations caused by an earthquake can be as large as the bearing gap, the frequency is the frequency of the seismic wave or the natural frequency of the system, so the rated rotation frequency It has the characteristic of being sufficiently lower than Therefore, even if rubbing occurs due to this vibration, since it does not have a rotational synchronization component, it will not lead to local heating of the rotor and will not lead to bending. The large vibrations excited by seismic waves will converge once the seismic motion converges, and there is little risk of developing into a divergent imaging phenomenon, and it can be said to have extremely stable properties.

Therefore, the limit for safe operation in this case is the strength of the bearing that supports the rotor system, and since it has sufficient margin against the limit value for normal operation, it can withstand large vibrations caused by seismic waves. There is no need to apply such vibration limit values for normal operation, and therefore safety will not be compromised in any way by not detecting this large vibration, or by preventing automatic trip even if it is detected. It turns out. The former means corresponds to a low frequency cut filter or a bandpass filter, and the latter means corresponds to a timer.

Furthermore, when switching from the starting circuit to the load operation circuit, in the first embodiment shown in FIG. 6, the starting circuit is also provided with an earthquake filter 23, so that it will not trip in an earthquake of medium or lower magnitude. There is no need to worry; the second embodiment is urgently needed. On the other hand, in the third embodiment, since a bandpass filter is used in the load operation circuit,
Naturally, the switching must be performed after the rated rotational speed is reached.

For reverse switching from the startup circuit to the load operation circuit,
Would it be better if the timing was opposite to the above-mentioned forward switching timing? I[
The 1llll theory from the system, starting when the rotation starts from the rated rotation speed, and passing the lowest natural frequency of the rotor system when the rotation decreases, is adopted to deal with the next startup.

〔Effect of the invention〕

As explained above, in the present invention, seismic waves and vibration signals of large vibrations excited in the turbine/generator shaft system by the seismic waves are cut by a frequency band filter before being input to the comparison/judgment device, and the remaining large vibration signals are The trip signal from the vibration component comparison/judgment device is blocked by a timer set according to the characteristics of the above-mentioned filter, thereby preventing inadvertent tripping when shaft vibration increases due to earthquake motion. , it is possible to continue operation to near the limits of the strength of the equipment. Therefore, the turbine generator will not trip due to a small earthquake, significantly improving operational durability, providing a more stable power supply, and preventing disruptions caused by large power outages. can be prevented.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the turbine shaft system, Fig. 2 is an explanatory diagram of the mounting structure of the vibration meter of the vibration monitoring device on the bearing, Fig. 3 is a schematic system diagram of the conventional turbine vibration monitoring device, and Fig. 4 is the basics. 5 is a longitudinal sectional view of the bearing part of the turbine generator including the stand; FIG. 5 is a diagram modeling the vibration system of the device in FIG. 4; FIG. 6 is a schematic system diagram of the turbine vibration monitoring device of the present invention; Figure 7 is a diagram showing the frequency components of seismic waves, Figure 8 is a vibration characteristic diagram of the rotor system of a turbine/generator, Figure 9 is a diagram showing seismic waveforms, and Figure 10 is a diagram of the turbine/generator affected by earthquake waves. A diagram showing the vibration characteristics of the rotor system of a generator, FIG. 11 is an explanatory diagram of the idea of vibration monitoring according to the present invention, FIG. 12 is a characteristic diagram of a filter in an embodiment of the present invention, FIGS. 13 and 16 14 is a characteristic diagram of the filter in the present invention, FIGS. 15 and 17 are diagrams showing the vibration characteristics after passing through the filter, and FIG. 18 is a diagram showing the vibration characteristics after passing through the filter. The figure shows the relationship between the magnitude of the earthquake and the duration of the main motion of the earthquake, FIG. 19 is a diagram explaining the manual trip operation, and FIG. 20 is a diagram explaining the operation of the alarm device. 6... Vibration meter, 13... Integrator, 15... Comparison judgment device, 17... Trip device, 23... Earthquake filter, 24... Low frequency cut filter, 25.2
6゜32...Timer, 31...Band pass filter. Applicant's representative Kiyoshi Inomata 6th session 16 Peripheral area 1 sentence (Hz) Figure 9 - Juyuu Te! 4th section 15th section

Claims (1)

[Claims] 1. A vibration detection device that continuously detects vibrations of a rotating shaft;
The vibration signal detected by the vibration detection device is compared with a predetermined vibration limit value, and if the vibration signal exceeds the vibration control value, a comparison judgment is made to output a trip signal to automatically stop the unit. In a turbine vibration monitoring device having an automatic trip device that automatically stops the unit by inputting a trip signal from the device, the vibration detection circuit is used mainly during startup, which is used when the rotation of the turbine/generator increases, such as during startup. It consists of two circuits: a circuit for use and a circuit for load operation, which is mainly used after addition to the grid.
At least the load operation circuit has a filter that cuts a specific frequency range of the vibration signal detected by the vibration detection device, and a filter corresponding to the start-up circuit is provided between the comparison judgment device and the automatic trip device. The turbine vibration monitoring system is characterized in that a timer is installed to stop the trip signal for a certain period of time, and the combination of these two circuits and timers can be switched depending on the operating conditions of the turbine/generator. Device. 2. The filter that cuts a specific frequency range is a filter that only passes vibration signals with a frequency higher than the lowest natural frequency of the turbine/generator shaft system, as set forth in claim 1. Turbine vibration monitoring equipment. 3. Turbine vibration according to claim 1, wherein the filter that cuts a specific frequency range is a filter that only passes vibration signals with a frequency of the rated rotational speed component of the turbine/generator shaft system. Monitoring equipment. 4. The turbine vibration monitoring device according to claim 1, wherein the starting circuit includes a filter that passes only vibration signals having a frequency exceeding the predominant frequency of an earthquake. 5. The turbine vibration monitoring device according to claim 1, wherein the setting time of the timer corresponding to the starting circuit is set to 2 seconds or less with the main purpose of preventing mistrips due to erroneous signals. . 6. The filter for the load operation circuit should be a filter that only passes vibration signals with a frequency equal to or higher than the lowest eigensignal number of the turbine/generator shaft system, and the timer corresponding to the filter should be set to 5 to 30 seconds. A turbine vibration monitoring device according to claim 1, characterized in that: 7. Make sure that the filter for the load operation circuit is a filter that only passes vibration signals with the frequency of the rated rotational speed component of the turbine/generator shaft system, and that the timer corresponding to that filter is set to 4 to 6 seconds. A turbine/vibration monitoring device according to claim 1, characterized in that: