JPH1030603A - Electropneumatic positioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To announce what kind of abnormality occurs to the central monitoring device side by a method wherein abnormality of a positioner itself and a regulation valve is diagnosed without increasing the load of a host control device and increasing a system cost. SOLUTION: A controller 5B is provided with a diagnosing function to diagnose a plurality of diagnosis items regarding the states of a regulation valve 3 and a positioner itself in addition to a function to generate a drive control signal to an electropneumatic converting part 5C. For example, a controller 5B diagnoses the actual opening X of the regulation valve 3 and whether hunting occurs based on a set opening R from a host control device and the actual opening X from the regulation valve 3. When it is decided that hunting occurs, diagnostic information A to indicate a diagnostic item and a diagnostic content is fed to a central monitoring device through the host control device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generates a drive control signal based on set opening information from a host controller and actual opening information from a control valve, and converts the drive control signal into a pneumatic signal. The present invention relates to an electropneumatic positioner for controlling a flow rate of a fluid passing through a control valve.

[0002]

2. Description of the Related Art Conventionally, an electropneumatic positioner is provided for a control valve, and the flow rate of a fluid passing through the control valve is controlled by the electropneumatic positioner. In this case, the electropneumatic positioner calculates a deviation between the set opening from the higher-level control device and the actual opening from the control valve, generates a drive control signal that makes this deviation zero, and generates the drive control signal. It is converted into a pneumatic signal and given to the control valve. If an abnormality occurs in the electropneumatic positioner or the control valve, the flow rate control of the fluid passing through the control valve is hindered. As a result, for example, an unexpected situation such as a sudden stoppage of the plant occurs, and the production is seriously damaged. Therefore, conventionally, in order to prevent such an unexpected situation, abnormality diagnosis of the electropneumatic positioner and the control valve is performed by the host controller.

[0003]

However, when the abnormality diagnosis of the electropneumatic positioner and the control valve is performed by the higher-level control device, the higher-level control device is usually controlled by a plurality (about several tens to one hundred). Since the control or monitoring of the target or the monitoring target is performed, a further heavy load is imposed on the abnormality diagnosis. As a way to prevent this,
There is a method of providing a separate abnormality diagnosis device, but this method increases the cost of the system. Conventionally, when it is determined that an abnormality has occurred, only a uniform alarm signal is sent to the central monitoring device. Therefore, even if the central monitoring device knows that an abnormality has occurred, Without knowing, the maintenance worker had to actually go to the site and investigate each one to identify the abnormal part.

The present invention has been made in order to solve such problems, and an object of the present invention is to reduce the load on the host controller and increase the system cost without increasing the system cost. Another object of the present invention is to provide an electropneumatic positioner capable of performing abnormality diagnosis of a control valve and notifying the central monitoring device of what abnormality has occurred.

[0005]

In order to achieve such an object, a first invention (an invention according to claim 1) is directed to the above-described electropneumatic positioner, in which a plurality of states of the control valve and the positioner are provided. Diagnostic means for diagnosing the diagnostic item, and diagnostic content output means for outputting a signal indicating the diagnostic item and the diagnostic content diagnosed by the diagnostic means. According to the present invention, the electropneumatic positioner has an abnormality diagnosis function, and diagnoses a plurality of diagnosis items with respect to the state of the control valve and the positioner itself. Then, the electropneumatic positioner outputs a signal indicating the diagnosed diagnosis item and the content of the diagnosis.

[0006] The second invention (the invention according to claim 2) is the first invention.
In the present invention, the hunting of the actual opening of the control valve is regarded as one diagnostic item, and this is diagnosed based on the set opening information from the host controller and the actual opening information from the control valve. According to the present invention, based on the set opening information from the host controller and the actual opening information from the control valve,
Hunting of the actual opening of the control valve is diagnosed. According to a third invention (an invention according to claim 3), in the first invention, deterioration of responsiveness of the actual opening of the control valve to the set opening is set as one diagnostic item, and this is set opening information from the host controller. In addition, the diagnosis is made based on the actual opening degree information from the control valve. According to the present invention, the deterioration of the responsiveness of the control valve to the set opening is diagnosed based on the set opening information from the host control device and the actual opening information from the control valve.

The fourth invention (the invention according to claim 4) is the first invention.
In the present invention, the deterioration of the control valve is regarded as one diagnostic item, and the diagnosis is made based on the actual opening degree information from the control valve and the flow rate value information of the fluid passing through the control valve.
According to the present invention, the deterioration of the control valve is diagnosed based on the actual opening degree information from the control valve and the flow rate value information of the fluid passing through the control valve. The fifth invention (the invention according to claim 5)
In the first invention, after diagnosing the diagnostic items of the positioner itself and determining that the electropneumatic positioner is normal, the diagnostic items of the control valve are diagnosed. According to the present invention, if the diagnosis item of the positioner itself is diagnosed and it is determined that the electropneumatic positioner is normal, the diagnosis item of the control valve is diagnosed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. FIG. 1 is a configuration diagram showing a main part of an electropneumatic positioner showing an embodiment of the present invention, and FIG. 2 is a system configuration diagram of a flow control system using the electropneumatic positioner.

In FIG. 2, reference numeral 1 denotes a central monitoring device;
1 and 2-2 are higher-level control devices, 3-1 and 3-2 are control valves,
Reference numerals 4-1 and 4-2 denote flow meters for detecting flow values of fluids passing through the control valves 3-1 and 3-2, and reference numerals 5-1 and 5-2 denote electropneumatic positioners according to the present invention.

The electropneumatic positioner 5 (5-1, 5-2)
As shown in FIG. 1, an input / output interface 5A, a controller 5B, an electropneumatic converter 5C, a pilot relay 5
D, a valve lift detector 5E and a deviation calculator 5F. In the electropneumatic positioner 5 (5-1, 5-2), the input / output interface 5A includes the host controller 2
Opening degree R (R1, R2) from -1 and flow meter 4
The flow value F from (4-1, 4-2) is given. Further, the valve lift detection unit 5E is provided with the control valve 3 (3-1, 3-
The actual opening X (X1, X2) of the control valve 3 (3-1, 3-2) is obtained from the valve lift position of 2), and is sent to the deviation calculation unit 5F.

The deviation calculating section 5F is provided with a set opening R from the host controller 2-1 via the input / output interface 5A.
And a deviation e (e = R−X) from the actual opening X from the control valve 3 via the valve lift detection unit 5E to the controller 5B. The controller 5B calculates the deviation e from the deviation calculation unit 5F.
Is generated, and the electropneumatic converter 5
Send to C. The electropneumatic converter 5C converts the drive control signal from the controller 5B into a pneumatic signal, and provides the pneumatic signal to the control valve 3 via the pilot relay 5D. Thereby, the actual opening X of the control valve 3 is adjusted to be the set opening R, and the flow rate of the fluid flowing through the control valve 3 is controlled to a desired flow value.

The controller 5B has, in addition to the function of generating a drive control signal to the electropneumatic converter 5C, a diagnostic function of diagnosing a plurality of diagnostic items with respect to the state of the control valve 3 and the positioner itself. The diagnostic function will be described with specific diagnostic items listed, together with the operation of the controller 5B.

[Diagnosis item 1: Hunting] Hunting may occur in the actual opening X of the control valve 3. This hunting is mainly caused by the PID parameter of the electropneumatic positioner 5 being too strong. In this case, the controller 5B communicates with the host controller 2-1 via the input / output interface 5A.
It is determined whether or not hunting has occurred based on the set opening R from the control valve 3 and the actual opening X from the control valve 3 via the valve lift detector 5E.

That is, the controller 5B adds the upper limit value R to the set opening R by adding ε as an allowable overshoot amount.
+ Ε is determined (see FIG. 3), and ε is subtracted from the set opening R as an allowable overshoot amount to determine a lower limit value R−ε. Then, the actual opening X is monitored, and when the actual opening X reaches the upper limit value R + ε (point t ₁ shown in FIG. 3), the timer operation of the timer is started. Then, during the time Δt until the timer finishes its timekeeping operation, the point at which the actual opening X crosses the upper limit value R + ε and the lower limit value R−ε is set as the target point (t
_{1 to} t ₈ ), and the number of times of this target point is counted. If the number of target points is i or more, it is determined that hunting has occurred.

In the above description, the allowable overshoot amount ε, the timer time Δt, and the number i of target points are determined in advance as set values. In the above description, the point at which the actual opening X intersects the upper limit value R + ε and the lower limit value R−ε is set as the target point (intersection), but X> R + ε and dx / dt.
= 0 (points t ₉ and t ₁₁ shown in FIG. 3), and points X <R−ε and dx / dt = 0 (points t ₁₀ and t ₁₂ shown in FIG. 3) are target points (inflection points). It may be.

When the controller 5B determines that hunting has occurred based on the above-described diagnosis, the controller 5B controls the diagnostic information A indicating the diagnosis item (hunting) and the contents of the diagnosis (occurrence of hunting) via the input / output interface 5A. The information is sent to the central monitoring device 1 via the device 2-1. Based on the transmitted diagnostic information A, the operator at the central monitoring device 1 can know that hunting has occurred. In this case, the main reason for the maintenance may be that the PID parameter of the electropneumatic positioner 5 is too strong. Therefore, the operator resets the PID parameter using the setting device.

[Diagnosis item 2: Deterioration of responsiveness] The responsiveness of the control valve 3 to the set opening R of the actual opening X may be deteriorated. The deterioration of the response is caused by the PI of the electropneumatic positioner 5
D parameter is too weak, deterioration of operation of valve shaft of control valve 3 (fixation of fluid, consumption of lubricant, etc.), deterioration of air flow [air leakage of actuator (actuator) of control valve 3, electropneumatic positioner 5 air circuit blockage (fixed throttle,
Nozzle flapper, pilot relay, etc.)]. In this case, the controller 5B has a responsiveness based on the set opening R from the host controller 2-1 via the input / output interface 5A and the actual opening X from the control valve 3 via the valve lift detection unit 5E. Diagnose whether it is getting worse.

[Diagnosis processing of deterioration of responsiveness]
When the set opening R is changed, the controller 5B calculates the absolute value of the difference between the set opening R and the actual opening X by a deviation e (e = | R−
X |) (step 401 shown in FIG. 4), and the timer operation is started (timer on) (step 402). Then, the obtained deviation e is compared with a preset deviation e _s (step 403), and e ≧
If e _s , proceed to step 404. Here, _assuming that the deviation (initial deviation) e ₀ at the time when the set opening R is changed is _{equal to} or more than e _s (see FIG. 5), e ≧ _es , so the flow proceeds to step 404.

In step 404, the time count t of the timer started in step 402 is compared with a predetermined set time t _s . Here, if t <t _s, returns through step 405 to step 403. In this case, when the e <e _s between until t ≧ t _s, i.e. the deviation e is set until the time t of the timer reaches the set time t _s, as shown by the characteristic I 5 Deviation e _s
If it is less than the predetermined time, the process proceeds to step 406 in response to NO in step 403, and the timer operation started in step 402 is reset (timer off).

[0020] On the contrary, if not the e <e _s between until t ≧ t _s, that is, the time t of the timer as indicated by characteristic II in FIG. 5 reaches the set time t _s If the deviation e still does not fall below the set deviation e _s , step 4
In response to YES in step 04, the process proceeds to step 407, where "alarm on" is set. That is, the controller 5B determines in step 407 that the responsiveness has deteriorated,
The diagnostic information A indicating the diagnosis item (deterioration of responsiveness) and the content of the diagnosis (deterioration of responsiveness) is sent to the central monitoring device 1 via the upper control device 2-1 via the input / output interface 5A.

From the transmitted diagnostic information A, the operator at the central monitoring device 1 can know that the responsiveness has deteriorated. In this case, the main factors for the maintenance include the PID parameter of the electropneumatic positioner 5 which is too weak, the deterioration of the operation of the valve shaft of the control valve 3 and the deterioration of the air flow. Is used to reset the PID parameters. In the case of a factor, the periphery of the valve shaft is checked, and in the case of a factor, cleaning or component replacement is performed.

In step 407, "alarm on"
After the, if the e <e _s (t _a point shown in FIG. 5), in accordance with the NO at step 403 step 406,405
Then, the timer operation started in step 402 is reset, and "alarm on" in step 407 is set to "alarm off". Therefore, FIG.
For characteristic II as shown in, only during t _s ~t _a, it is the "alarm on".

[0023] In the [responsiveness diagnosis processing worsening] above, it did not set or one time setting t _s, may be determined more time setting t _s. By determining a plurality of set times t _s , it is possible to classify the state of responsiveness deterioration such as “slight injury”, “severe injury”, and the like.

For example, as shown in FIG. 7, two types of set times t _s1 and t _s2 are determined (t _s1 <t _s2 ). In this case, when the set opening degree R is changed, the controller 5B
The absolute value of the difference between the set opening R and the actual opening X is represented by a deviation e (e = |
R−X |) (step 601 shown in FIG. 6),
The timer operation of the timer is started (step 602).
Then, the obtained deviation e is compared with a preset deviation e _s (step 603), and if e ≧ e _s , the flow proceeds to step 604.

In step 604, the timer time t started in step 602 is compared with a predetermined set time t _s1 . If t <t _s1 , the process returns to step 603 via step 605. In this case, when the e <e _s between until t ≧ t _s1, i.e., the deviation e is set until the measured time t of the timer as shown by a characteristic I in FIG. 7 reaches the preset time t _s1 Deviation e _s
If it is less than, the process proceeds to step 606 in response to NO in step 603, and the timer operation started in step 602 is reset.

[0026] On the contrary, if not the e <e _s between until t ≧ t _s1, i.e. characteristic II in FIG. 7, III
If the deviation e does not fall below the set deviation e _s even after the timer time t reaches t _s1 , as shown by,
The process proceeds to step 607 in response to YES in step 4. In step 607, the time count t of the timer is compared with a predetermined set time t _s2 . Here, if t < _ts2 ,
Proceeding to step 608, "alarm 1 on" is set. That is, the controller 5B determines in step 608 that the responsiveness has deteriorated, and sends the diagnostic information A indicating the diagnostic item (reactive responsiveness), the diagnostic content (reactive responsiveness occurrence), and the type (minor injury). To the central monitoring device 1 via the host controller 2-1 via the input / output interface 5A.

Then, returning to step 603, the same operation as described above is repeated. Here, after the "alarm 1 ON" at step 608, if the e <e _s until the time t of the timer reaches t _s2 (t shown in FIG. 7
_a point), and according to NO in step 603, step 60
The process proceeds to 6,705, in which the timer operation started in step 602 is reset, and “alarm 1 on” in step 608 is changed to “alarm 1 off”. Therefore, if the characteristic II as shown in FIG. 7, only during the t _s1 ~t _a, is the "alarm 1 ON".

On the other hand, after “alarm 1 is turned on” in step 608, e <e _s until t ≧ t _s2.
In other words, if the deviation e does not fall below the set deviation e _s even if the timer time t reaches the set time t _s2 as shown by the characteristic III in FIG.
In response to YES in step S 609, the process proceeds to step 609 to set “Alarm 1 off” and then set “Alarm 2 on”. That is, the controller 5B determines in step 609 that the responsiveness is further deteriorated, and the diagnostic information A indicating the diagnosis item (deterioration of responsiveness), the diagnostic content (deterioration of responsiveness occurrence), and the type (serious injury). Is transmitted to the central monitoring device 1 via the host controller 2-1 via the input / output interface 5A.

Then, returning to step 603, the same operation as described above is repeated. Here, after the "alarm 2 ON" at step 609, if the e <e _s (t _b point shown in FIG. 7), in accordance with the NO at step 603 Step 6
06, 705, and resets the time counting operation of the timer started in step 602;
"Alarm 2 on" in the above is referred to as "Alarm 2 off".
Therefore, in the case of the characteristic III shown in FIG. 7, t _{s1 to} t _s2
During this time, the alarm 1 is turned on, and between t _s2 and t _b , the alarm 2 is turned on.

[Diagnosis item 3: Deterioration of control valve] The control valve 3 may be deteriorated. That is, in the relationship between the actual opening X of the control valve 3 and the flow rate value F, a shift of the zero point and a drop of the span may occur. The shift of the zero point is mainly caused by wear of the plug and the seat ring (the fluid does not flow completely even at the zero point position). The main cause of the drop of the span is leakage to the outside from the gland packing or the like (fluid leaks outside due to wear of the gland packing or loosening of the bolt, and the span cannot be secured). In this case, the controller 5B determines that the control valve 3 has deteriorated based on the actual opening degree X from the control valve 3 via the valve lift detection unit 5E and the flow rate value F of the fluid passing through the control valve 3 via the flow meter 4. Diagnose whether or not.

[Diagnosis Process of Deterioration of Control Valve (Shift Diagnosis Process of Zero Point)] The controller 5B determines the normal relationship between the actual opening degree X of the control valve 3 and the flow rate value F = aX + b (a>).
0, b = 0) (characteristic I shown in FIG. 8).
reference). Also, ε ₁ (ε ₁ > 0) is set in advance as the threshold value of b, and the actual relation is expressed as F = aX + b (b> ε
_{When 1} ) is satisfied, it is determined that the shift is a zero point.

That is, the controller 5B determines the actual opening degree X from the control valve 3 via the valve lift detecting section 5E and the flow meter 4
The flow rate value F of the fluid passing through the control valve 3 via the control valve 3 is taken in and substituted into F = aX + b (step 90 shown in FIG. 9).
1). Then, a b a b = F-aX, compares the b threshold epsilon ₁ (step 902). here,
If b ≦ epsilon ₁ whereas it is determined to be normal (Step 9
03), b> ε ₁ is long if the abnormality (zero point shift: reference characteristic II shown in FIG. 8) and determines (step 904). Then, the controller 5B generates diagnostic information A indicating the diagnostic item (deterioration of the control valve) and the diagnostic content (shift of the zero point).
Is sent to the central monitoring device 1 via the upper control device 2-1 via the input / output interface 5A (step 90).
5).

From the transmitted diagnostic information A, the operator at the central monitoring device 1 can know that the control valve 4 is degraded (shift of the zero point). In this case, since the main cause of the maintenance is considered to be wear of the plug and the seat ring, the operator replaces the parts of the control valve 4.

[Diagnosis Processing of Control Valve Deterioration (Drop Diagnosis Processing of Span)] The controller 5B determines the normal relationship between the actual opening degree X of the control valve 3 and the flow rate value F = aX + b.
(A> 0, b = 0) is stored (see the characteristic I shown in FIG. 10). Also, as the threshold value of b, −ε ₂ (ε
₂ > 0) is set in advance, and the actual relation is F = aX +
If b (b <−ε ₂ ), it is determined that the span has dropped. The control valve deterioration diagnosis process is performed when it is confirmed that there is no shift of the zero point in the control valve deterioration diagnosis process.

That is, if the controller 5B determines that the shift is zero in the zero shift diagnosis process (step 111 shown in FIG. 11), the controller 5B controls the control valve 3 via the valve lift detector 5E.
And the flow rate value F of the fluid passing through the control valve 3 via the flow meter 4 are taken in, and substituted into F = aX + b (step 112). Then, b is obtained as b = F−aX, and this b is compared with a threshold value −ε ₂ (step 1).
13).

Here, if b ≧ −ε ₂ , it is determined to be normal (step 114), whereas if b <−ε ₂ , it is determined to be abnormal (span drop: see characteristic III shown in FIG. 10). (Step 115). And the controller 5
B sends the diagnostic information A indicating the diagnostic item (deterioration of the control valve) and the content of the diagnosis (drop of span) to the central monitoring device 1 via the host controller 2-1 via the input / output interface 5A (step). 116).

From the sent diagnostic information A, the operator at the central monitoring device 1 can know that the control valve 4 has been degraded (span drop). In this case, the main reason for the maintenance is leakage to the outside from the gland packing or the like. Therefore, the operator replaces the parts of the control valve 4.

In the above description, the electropneumatic positioner 5
And the control valve 3 are diagnosed simultaneously. However, diagnostic items are separately defined for the electro-pneumatic positioner 5 and the control valve 3, and the diagnostic items of the positioner itself are diagnosed to determine that the electro-pneumatic positioner 5 is normal. After that, the diagnosis of the control valve 3 may be performed.

[0039]

As is apparent from the above description, according to the present invention, the electropneumatic positioner has an abnormality diagnosis function,
Diagnosis of multiple diagnostic items for the status of the control valve and the positioner itself, and outputs a signal indicating the diagnosed diagnostic item and the content of the diagnosis, so that the host controller does not become a heavy load and separate abnormalities There is no increase in the cost of the system as in the case of providing a diagnostic device. Further, it is possible to inform the central monitoring device of what kind of abnormality has occurred, and quick and appropriate maintenance can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a main part of an electropneumatic positioner according to an embodiment of the present invention.

FIG. 2 is a system configuration diagram of a flow control system using the electropneumatic positioner.

FIG. 3 is a diagram illustrating a hunting diagnosis process in the electropneumatic positioner.

FIG. 4 is a flowchart for explaining a diagnosis process of deterioration of responsiveness in the electropneumatic positioner.

FIG. 5 is a characteristic diagram for explaining a process of diagnosing deterioration of responsiveness in the electropneumatic positioner.

FIG. 6 is a flowchart for explaining a diagnosis process of deterioration of responsiveness in the electropneumatic positioner.

FIG. 7 is a characteristic diagram for explaining a process of diagnosing deterioration of responsiveness in the electropneumatic positioner.

FIG. 8 is a characteristic diagram for explaining a diagnosis process (zero-point shift diagnosis process) of deterioration of a control valve in the electropneumatic positioner.

FIG. 9 is a flowchart illustrating a process of diagnosing deterioration of a control valve in the electropneumatic positioner.

FIG. 10 is a characteristic diagram for explaining a process of diagnosing deterioration of a control valve (span diagnosing process) in the electropneumatic positioner.

FIG. 11 is a flowchart illustrating a process of diagnosing deterioration of a control valve in the electropneumatic positioner.

[Explanation of symbols]

1 central monitoring device, 2 (2-1, 2-2) ... host controller, 3 (3-1, 3-2) ... control valve, 4 (4-1, 4-)
2) Flow meter, 5 (5-1, 5-2) electropneumatic positioner, 5A input / output interface, 5B controller, 5C electropneumatic converter, 5D pilot relay, 5
E: valve lift detector, 5F: deviation calculator.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Fumio Nagasaka, inventor Yamatake Ha Newel Co., Ltd. 2-12-19 Shibuya, Shibuya-ku, Tokyo

Claims (5)

[Claims] 1. A drive control signal is generated based on set opening information from a host controller and actual opening information from a control valve, and the drive control signal is converted into a pneumatic signal and passes through the control valve. In an electropneumatic positioner for controlling a flow rate of a fluid, diagnostic means for diagnosing a plurality of diagnostic items with respect to the state of the control valve and the positioner itself, and outputting a signal indicating the diagnostic items and diagnostic contents diagnosed by the diagnostic means An electro-pneumatic positioner, comprising: a diagnostic content output unit that performs diagnosis. 2. The method according to claim 1, wherein the hunting of the actual opening of the control valve is defined as one diagnostic item, and the hunting is performed based on the set opening information from the host controller and the actual opening information from the control valve. Electro-pneumatic positioner characterized by the following. 3. The method according to claim 1, wherein the deterioration of the responsiveness of the actual opening of the control valve with respect to the set opening is regarded as one diagnostic item, which is set opening information from the host controller and the actual opening from the control valve. An electropneumatic positioner characterized by making a diagnosis based on information. 4. The method according to claim 1, wherein the deterioration of the control valve is regarded as one diagnostic item, and the deterioration is diagnosed based on information on the actual opening from the control valve and information on the flow rate of the fluid passing through the control valve. Electro-pneumatic positioner. 5. The electropneumatic positioner according to claim 1, wherein a diagnosis item of the control valve is diagnosed after diagnosing a diagnosis item of the positioner itself and determining that the electropneumatic positioner is normal.