JPS6320501A - Automatic controller for operation terminal - Google Patents

Abstract

PURPOSE:To prevent disturbance and damage caused by the disturbance from occurring to a plant at the time of the recovery of a driving source (air source) by adding a circuit which makes a command for the degree of opening of an operation terminal coincident with the actual degree of opening when the abnormality of the operation terminal is detected and it is decided that the operation terminal is in a lock state. CONSTITUTION:An abnormality detecting circuit 202 for the operation terminal 61 detects the mutual relation between the opening degree of the operation terminal 61 and a process variable to be controlled or a process variable with close mutual relation because the mutual relation is determined unequivocally in the operation state of the plant. A test and lock deciding circuit 203 inputs a test operation signal to the operation terminal 61 when the abnormality detecting circuit 202 detects abnormality and detects whether there or not is a response to it from variation is process variable, thereby deciding the lock state of the operation terminal. When a decision circuit 203 decides the operation terminal lock state, a reset circuit 204 makes the operation command coincident with the degree of opening estimated from the process variable. Consequently, the degree of opening of the operation terminal 61 is prevented from varying abruptly at the time of unlocking.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an automatic control device for an operating end, particularly an automatic control device for an operating end in a thermal power plant, etc. An automatic control device for the operating end that is suitable for handling abnormalities at the operating end due to loss of the drive air source, etc. 'do.

[Conventional technology]

Pneumatic operating terminals are often used as operating terminals for control devices in thermal power plants, from the viewpoint of safety and explosion protection and because the construction of operation 1 is extremely simple. By the way, in the event of an abnormality such as a problem with the drive air source, the operation f'F. The ends are locked, so
The interface between the automatic controller and the operating end requires a complex interlock circuit.

Additionally, some existing plants simply issue an alarm even in the event of an abnormality as described above, and are not provided with an interlock circuit.

2 to 5 show examples of conventional control circuits for pneumatic operating ends.

1 in FIG. 2 is a control device. 11 is control setting 1
It is a setting device that gives [. Its output is applied to comparator 12 and compared with the process quantity detected by detector 31. The comparison result is input to the proportional/integrator 13. Proportional/
The output of the integrator 13 is input to a voltage/current converter 15 via an automatic/manual switch 14.

16 is a manual operating device for manually operating the operating end. l
7 is a circuit for switching between automatic and manual control. Also 18
is an interlock circuit for locking the operating end, and the details are shown in FIG. 3. 51 is a current/air pressure converter, which generates air pressure corresponding to the operation command that is the output of the voltage/current converter 15. Air pressure to the current/air pressure converter 51 is supplied from an air source 52 to a pressure reducing valve 53. It is supplied under reduced pressure through the A pressure switch 70 monitors the air pressure of the air source 52. A pressure switch 54 monitors the air pressure supplied to the air flow/air pressure converter 51.

The output of the current/air pressure converter 51 is transmitted through a locking solenoid valve 55 controlled by an interlock circuit 18.
The operating end 61 is operated in accordance with the input air pressure input to the position adjuster 56. Bojishi 1su5
6 is supplied from an air source 52 via a pressure reducing valve 57 after being reduced in pressure.

A pressure switch 58 monitors the air pressure supplied to the exhaust gas 56. Reference numeral 59 denotes a selector relay, which releases the air supplied to the locking valve 60 to the atmosphere and locks the operating end 61 when the supply pressure to the positive switch 56 falls below a specified value.

FIG. 3 shows the contents of the interlock circuit 18 for locking the operating end. 101 is an OR circuit, and conditions 102-1
05 is input, and its output operates the locking feature valve 55, and the automatic/manual switching circuit 17 operates.
Switch control from automatic to manual.

Here, the condition 102 is a power failure of the control device 1. Condition 103 is an abnormal condition on the electrical side, such as failure of the voltage/current converter 15 and current/pneumatic converter 51 themselves, or disconnection of the cable between them.

Condition 104 is the detection of air source loss by the pressure switch 54. Condition 105 is the detection result of air source loss by the pressure switch 58, and these are abnormal conditions on the driving air source side.

Thus, for the operation of one unit, a pressure switch for monitoring the normality of the air source for both the flow/air pressure converter and the position 1, and an interlock thereof are required. Incidentally, related devices of type C include, for example, Japanese Patent Application No. 60-223563.

The above are examples of newly constructed plants and large-scale plants.
Some existing plants and small and medium-sized plants have a control circuit as shown in Figure 4.

Components with the same numbers as in FIG. 2 in FIG. 4 operate in the same way as in FIG. 2.

The difference between FIG. 4 and FIG. 2 is that (1) the pressure switches 54 and 58 for monitoring the air pressure in the supply chamber to the current/air pressure device 51 and positioner 56 are omitted in FIG. 4; , and (2) the interlock circuits 19 for locking the operating end are different.

There are two points.

FIG. 5 shows details of the Innotarlock circuit 19.

Components in FIG. 5 with the same numbers as in FIG. 3 operate in the same way as in FIG. 3. The difference from FIG. 3 is that conditions 104 and 105 are not present, that is, the abnormal condition on the air side, which is the loss of the air source for driving the operating end, is omitted.

In the case of a control circuit configured as shown in FIG. 4, even if the operating end is locked due to failure of the air source for driving the operating end, the control remains automatic, so the pressure switch 70 allows the common air source to be When the loss of control is amortized and the alarm occurs, the operator must switch control from automatic to manual.

[Problem that the invention seeks to solve]

In the above conventional technology, for the reasons described below, the control continues automatic operation even though the operating end is in the locked state, and the operation command signal and the actual opening of the operating end (locked opening) Since the actual opening degree of the operating end suddenly changes toward the operation command signal when the operating end is unlocked, it may cause a large disturbance to the system or, in some cases, cause the system to malfunction. There was a problem that it could be damaged. This will be explained in more detail below.

In the circuit example shown in FIGS. 2 and 3, the operation setting value of the selector relay 59 that detects loss or reduction of the air source and operates the locking valve 60 to actually lock the operating end 61, and the pressure switch 58 are determined. The operation setting values of are set to be the same.

Then, the pressure switch 58 detects the loss of air pressure supplied to the positioner 56, and a command to switch to the manual state is given to the manual switching circuit 17 via the OR circuit 101. The control will not remain in automatic operation in the locked state of 61.

However, it is not uncommon for a difference to occur between the operating set value of the pressure switch 58 and the operating θ constant value of the selector relay 59 due to aging or the like.

Even in this case, if the air source is completely lost, both the pressure switch and the selector relay will detect an abnormality, so no particular problem will occur. In cases where pressure loss increases, pressure switch 58 and selector relay 5
Since there is a difference in the operation (timing) of 9, the operating end 6
It may become impossible to get used to the locked state of No. 1 accurately, and the III control may remain in the automatic operation state even though the operating end is in the locked state.

In the circuit example shown in FIGS. 4 and 5, the loss of the air source is detected only by the pressure switch 70, so the detection setting value, the pressure loss of the air supply, the setting of the pressure reducing valve 57, and the operation of the selector relay 59 are used. It becomes very difficult to implement settings and the like for each operating end.

In addition, since it is not possible to detect changes over time or clogging of individual pressure reducing valves (increased pressure loss in the piping system),
1 is locked, the operator may not be aware of the situation and the control may remain in the automatic operation state.

Next, with reference to FIG. 4, a problem that occurs when the automatic operation state of the control is continued with the operating end locked will be explained.

For example, there is an abnormality in the compressor (not shown) that makes up the air source 52, and the air pressure has gradually decreased, but the pressure switch 70 is still not operating, and there may be variations in piping loss or the setting of the pressure reducing valve 57. Due to the variation in values, the selector relay 59 at a certain operating end operates, and the locking valve 6
Let us consider a case where the operating end 61 is locked due to operation of the operating end 61.

At the time when the operating end 61 is locked, if the control vii difference, which is the output of the comparator 12, rarely occurs in a negative one shift, the operating end 61 will not move from then on, so the control deviation will also be the value of page.・On the other hand, since the control remains in the automatic state, the proportional/integral 41 input with the above negative deviation
The output No. 3 (opening degree command of the operating end) continues to decrease during lucidity, and continues to deviate from the actual opening degree of the locked operating end 61.

In this state, when the air loss in the air source 52 continues to decrease, the pressure switch 70 is activated. In response to the detection of such a pressure drop in the air source, the compressor standby unit (8
) is activated, pressure in the air source 52 is restored;
Selector relay 59 is also unlocked.

In this state, as described above (because the opening command for the operating end 61 is lower than the locked position of the operating end, the operating end 61 is rapidly narrowed toward the opening command. A sudden change in the operation end 61 causes a large disturbance to the plant, leading to a trip of the plant or, in the worst case, damage to the plant.

There are dozens to hundreds of such control terminals in a single plant, and since the operator does not know which control terminal has performed such an operation, it is difficult to properly handle sudden changes in the plant. It is extremely difficult to take corrective action (that is, to return the operating end to its original opening after a sudden change).

One measure to prepare for such a situation is, for example, to install a pressure switch like the one shown at 58 in Figure 2 on all the existing operation terminals, lay a cable from the site to the control equipment gt1, and It is conceivable to add an interlock circuit to the control device 1. However, it is not easy to install new cables to all operating terminals of the existing plant. Further, even if such cables and circuits are added, there is a problem that if there is a difference in the operation of the pressure switch 58 and the selector relay 59, the effect will be lost.

In the above, we have discussed the problems with operating bars that are driven and controlled by pneumatics, but the same problems occur not only with fluid systems such as hydraulics, but also with electric systems (pulse motors and servo motors). There is a point.

The purpose of the present invention is to accurately detect that the operating end is in a locked state without installing a new pressure switch or installing a new cable at the operating end of an existing plant, and to further detect abnormalities. It is an object of the present invention to provide an automatic control device for an operating end, which adjusts the opening degree command of the operating end to the actual opening degree when a state is released, and does not cause disturbance to a plant.

[Means for solving problems]

The above purpose is to provide a circuit for detecting abnormal operation of the operating end, a circuit for testing the operating end to determine whether it is in the locked state when this is detected, and a circuit for detecting whether the operating end is in the locked state. This is achieved by attaching a circuit to the control device that matches the opening degree command of the operating end with the actual opening degree.

[Effect]

The operating end and abnormality detection circuit focuses on the fact that the interrelationship between the opening of the operating end and the controlled process lid or a process amount with a strong correlation is uniquely determined by the operating state of the Habo plant.
Abnormalities are detected by checking these mutual relationships.

The test and lock determination circuit inputs a test operation signal to the operation terminal when the above-mentioned abnormality detection circuit detects common operation, and detects the presence or absence of the 5 answers from the change in the above-mentioned process amount. The reset circuit is configured to determine the lock state of the operating end. When the determination circuit determines that the operation end is in the locked state, the reset circuit causes the operation command to match the development estimated from the aforementioned process amount. It is something to keep.

By adding such a circuit, air (fluid pressure)
Since it is possible to prevent the opening degree of the operating end from suddenly changing when the lock is released due to power recovery, etc., it is possible to prevent disturbance from being caused to the plant and damage to the main body.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram showing an embodiment of the present invention. Components with the same numbers as in FIG. 4 operate in the same way.

201 is a function generator, based on the fact that the correlation between the process amount taken in from the detector 31 and the opening degree of the operating end 61 is almost uniquely determined for each operating end.
The opening degree of the operating end at that time is estimated from the process sensitivity. The functional relationship is set in advance, for example, as shown in the real image of FIG.

202 is an abnormality detection circuit of the operating end, and a function generator 20
1 output, that is, the opening degree of the operating end 61 estimated from the process cabinet, and the operating end opening command, which is the output of the automatic/manual switch 14, and for example, when the difference becomes more than a predetermined value ( In Figure 6, when the estimated opening degree falls within the shaded area),
Detects an abnormality. When an abnormality is detected, the alarm 210 is output, and the switch 18 (211) is switched to the automatic/manual switching circuit 17 (4) to switch the control from self-control (self-control force) to manual. Control signal 2
12 to the operating end lock test operation and determination circuit 203 to start the circuit.

The detailed operation of the abnormality detection circuit 202 is shown in the flowchart of FIG.

Step 250 is a determination as to whether the current state is such that abnormality detection can be performed. In other words, a certain condition is required to uniquely determine the process amount that is the output of the detector 31 and the opening degree of the operating end 61, and if that condition is not satisfied, detection is excluded (prohibited) and malfunction is caused. It is necessary to prevent this.

Examples of exclusion conditions include:

(Transient conditions such as 11 wide and rapid negative fI fluctuations.

(21FCB (Rapid load narrowing due to system accidents, etc.)

(3) Runback (operation with reduced output due to failure of large auxiliary equipment such as water pumps and forced/returning ventilation fans).

(4) When normal performance is not achieved due to unbalanced operation due to an abnormality in the auxiliary equipment, etc. - Step 251 generates a function 4 based on the actual opening command and the flow rate.
This is a check or evaluation of the difference from the opening estimated by 201.
A permissible width is determined in advance for each operating end according to the characteristics of the process, and it is determined whether the difference exceeds the permissible width.

Step 252 is a determination as to whether the abnormality in which the difference exceeds the allowable range is instantaneous or continuous.

If the abnormality is continuous, it is determined that the operating end is abnormal, and a warning is output in step 253.

Further, in step 254, the control is switched from automatic to manual, and in step 255, the test operation and determination circuit 203 is activated.

When the determinations in steps 251 and 252 are that "the difference between the opening command value and the estimated opening is within the allowable value" and that "the abnormality continues within the allowable time".

Since this operating end is normal, the process shown in FIG. 8 immediately ends.

By the process of step 255 described above, operation 1 in FIG.
When the zero test operation and determination circuit 203 is activated, it first gives a test operation command 213 to the 16 manual operation setting devices 16 to increase or decrease the amount permissible in the plant.

Then, the process value detected by the detector 31 is monitored, and if there is an e-response to check whether the value has changed by the expected amount within a specified time, that is, if the value has changed by the expected amount. determines that the operating end 61 is not locked, gives an automatic input command 215 to the automatic/manual switching circuit 17, and switches the control to automatic operation again.

If there is no response, it is determined that the operating end 61 is in the locked state, and the reset circuit 204 is activated by the reset circuit 214.
Start.

When activated, the reset circuit 204 gives the opening degree 1 216 of the operating end 61 estimated by the function generator 201 to the manual operation setting device 16, and converts the operation 1 opening command by manual operation into the estimated opening degree. Set the signal 216 trap equal to prepare for operation i eI rack release due to air source recovery, etc.

The processing procedure 1'@ described above is shown in the flowchart of FIG. Reference numerals 202 to 204 in FIG. 1 correspond to those in FIG. 1, and the processes lE! I am writing 7 works.

As shown in step 205 in FIG. 7, once the abnormality at the site has been investigated and restored, and the restoration has been completed, in step 206,
Operator switches control from manual to automatic.

Practical Example A (According to this example, the locked state of the operator's seat can be detected without adding a new pressure inlet or laying a cable to the operating end of an existing plant, and
Manual control of the operating end; Opening when the opening command is locked,
You can reset the length or something close to this.

Therefore, even if the control end is unlocked due to recovery or reconnaissance of the air source, the operating medium will not change suddenly, preventing disturbance or damage to the plant. effective.

Furthermore, even in plants where a pressure switch (58 in Figure 2) is installed, lock detection may become impossible due to a discrepancy in the operating settings between the pressure switch and the lock selector relay due to changes over time. The same effect as above can be obtained in such cases.

In the above, an example has been described in which the present invention is applied to an operating end controlled by pneumatic pressure. However, the present invention can be applied not only to a hydraulic type or other fluid type, but also to an electric type (pulse motor or servo motor type) operation. It will be easily understood that C can also be applied to end control.

Further, although the operating end is used to control the opening degree, it is needless to say that the operating end is not limited to this and may be used to control any other amount.

〔Effect of the invention〕

According to the present invention, the monitoring means (pressure switch) can be added even in an existing plant where there is no means (for example, a pressure switch for monitoring air pressure) of the drive source for operation every y% of operations. By detecting whether or not the operating end is locked and resetting the opening command of the operating end to the locked opening or its vicinity, the drive source can be This has the effect of preventing disturbances to the plant and damage caused by such disturbances when the air source is restored.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention, and FIG. 2 is a system diagram showing an embodiment of the present invention.
System diagram showing an example of a conventional automatic control device for an operating end, Part 3
The diagram shows the operations in Figure 2! A diagram showing the operation of the interlock circuit for locking, Fig. 4 is a system diagram showing another example of the conventional automatic control device for the operating end, and Fig. 5 shows the operating end 0 in Fig. 4.
FIG. 6 is a diagram showing an example of the correlation between the estimated opening degree of the operating end and the process amount, and FIGS. Al with flow chart to explain. DESCRIPTION OF SYMBOLS 1... Control g position, 12... Comparator, 14... Manual switch, 17... Automatic/manual switching circuit, 19... Interlock circuit, 31... Detector, 52... ... Air source, 56 ... Position 1, 61 ... Operation end, 202
... Control end abnormality detection circuit, 203 ... Control end lock test) N production and judgment circuit, 204 ... Reset circuit agent Patent attorney Michi Hiraki]
No. 1. figure
1 Figure 3 Figure 4 Figure 5 Figure 6 Process amount Figure 7

Claims (6)

[Claims] (1) An operating end for controlling a process amount, a drive source for driving the operating end, means for supplying an operation command signal to the operating end based on a deviation of the process amount from a target value, and a drive source. an automatic control device for an operating end, comprising: means for locking the operating end when the operating end becomes abnormal; means for estimating that the operation of the operating end is abnormal; means for applying a test operation signal to the operating end; means for determining whether or not the operating end has performed a predetermined action in response to the test operating signal; and when the operating end does not perform a predetermined action; An automatic control device for an operating end, comprising means for setting an operation command signal for the operating end to a value substantially equal to the amount of operation of the operating end at the time of estimation of an abnormality. (2) The means for estimating that the operation of the operating end is abnormal includes a means for detecting a process quantity, a means for estimating an operation command signal from the detected process quantity, and a means for estimating an operation command signal and an actual operation. 2. The automatic control device for an operating end according to claim 1, further comprising means for determining whether the difference from the command signal is less than or equal to a predetermined value. (3) Determination as to whether or not the operating end has performed a predetermined operation in response to the test operation signal is made based on whether or not the process amount has changed by more than a predetermined value in response to the test operation signal. An automatic control device for an operating end according to claim 1 or 2, characterized in that: (4) The automatic control device for an operating end according to any one of claims 1 to 3, wherein the drive source is a pressure fluid. (5) The automatic control device for an operating end according to claim 4, wherein the pressure fluid is air. (6) The value substantially equal to the operation amount of the operating end at the time of abnormality estimation is an operation command signal estimated based on the process amount at the time of abnormality estimation. automatic control device at the operating end of.