JP2003036115A - Method and device for diagnosing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that complicated statistical processing is needed to detect a stick slip phenomenon and hardly performed by a CPU with low processing capability used for field equipment or takes too long time to actualize. SOLUTION: The quantity of a signal of a valve opening extent, etc., which is proportional to a speed or acceleration is found and this signal is compared with a reference signal of a set point of a valve to diagnose the operation of equipment. The complicated statistical processing becomes unnecessary and even the CPU with low processing capability can take the diagnosis at a high speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for diagnosing field devices and the like in the field of process control, and particularly to a method and device for diagnosing stick-slip phenomenon of a control valve. It relates to the device.

[0002]

2. Description of the Related Art Field devices include sensor and actuator devices for the process industry, that is, transmitters and flow meters,
There is a valve positioner etc. Such field devices are based on the communication protocol for process industry, such as Foundation Fieldbus, PROFIBUS, HART, BRAIN, etc.
It communicates with the host system to receive the set values and the like, and also notifies the host system of the result of self-diagnosis. The higher-level system includes an interface device and a higher-level computer.

The stick-slip phenomenon is one of the causes of the malfunction of the control valve, which is one type of field device. The stick-slip phenomenon is a phenomenon in which sticking and slipping are repeated, and when the degree of this phenomenon increases, it becomes difficult for the positioner that controls the valve to control the valve, and oscillation (limit cycle) occurs.

In the intelligent positioner capable of communicating with the host system, it is possible to stop the oscillation by lowering the gain or giving a dead zone to the integration when the stick-slip phenomenon occurs, but the resolution of the valve is reduced accordingly. There is a drawback that

For example, Japanese Patent Application Laid-Open No. 10-47313 discloses an invention of an apparatus for detecting the occurrence of the stick-slip phenomenon by performing statistical processing. The outline of the invention described in this publication will be described below with reference to FIG.

In FIG. 7, the displacement detecting unit 5 detects the relative displacement of sliding of the valve, the first-order differential calculating unit 61 calculates the velocity component thereof, and the second-order differential calculating unit 7 calculates the acceleration component. These differential operations output the square sum of velocity or acceleration for a predetermined period as their value.

The characteristic storage unit 62 stores the relationship between the speed and the acceleration when the sliding is normal, for example, the acceleration is expressed by a linear expression of the speed. The second-order differential value estimation unit 63 estimates and outputs the acceleration component from the velocity component calculated by the first-order differential calculation unit 61 and the relational expression stored in the characteristic storage unit 62.

The diagnostic calculation unit 8 compares the acceleration component calculated by the second-order differential calculation unit 7 with the acceleration component in the normal state estimated by the second-order differential value estimation unit 63 to determine whether the stick-slip phenomenon has occurred. To diagnose. By doing so, the normal state and the current state can be compared in quantity, so that an accurate diagnosis can be performed.

[0009]

However, such a stick-slip detection device has the following problems.

As described above, in order to obtain the velocity component (first differential component) and acceleration component (second differential component) of the sliding displacement of the valve, statistical processing such as sum of squares is required.
There was a problem that it took time to perform numerical calculation.

Generally, the power consumption of a field device such as a valve positioner must be suppressed to about several mA to several tens of mA due to various restrictions such as intrinsic safety. Therefore, the microprocessor mounted on the field device must use a low power consumption and low calculation speed. Therefore, it is difficult to perform a complicated numerical operation, and even if it is forcibly performed, there is a problem that the practicality is poor due to responsiveness and the like.

[0012]

In order to solve such a problem, the invention according to claim 1 of the present invention is a method for diagnosing a device for diagnosing whether the device is operating normally. , A signal proportional to the speed or acceleration of a signal related to the device to be diagnosed and a reference signal related to this device are compared and calculated to diagnose whether or not the device is operating normally. . It can be diagnosed with simple processing.

According to a second aspect of the present invention, in the first aspect of the present invention, the level of the velocity or acceleration signal is compared with a predetermined threshold value for a predetermined time after the reference signal is changed. The diagnosis is made. Easy to diagnose.

According to a third aspect of the present invention, there is provided a device diagnostic device for diagnosing whether the device is operating normally, wherein a signal related to the device is input, and a signal proportional to the speed or acceleration of this signal is sent. It has a computing unit 1 for computing and outputting,
The device is diagnosed on the basis of the output of the arithmetic unit 1. Easy to diagnose.

According to a fourth aspect of the present invention, there is provided a device diagnostic device for diagnosing whether the device is operating normally, which relates to a signal proportional to the velocity or acceleration of a signal related to the device and the device. It has a comparison calculation unit 2 to which a reference signal is input, and the comparison calculation unit 2 compares and calculates a signal proportional to the speed or acceleration and the reference signal to determine whether the device is operating normally. It was made to diagnose. Diagnosis is possible even with a CPU with low processing capacity.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, a signal relating to the device is input, and a calculation unit 1 for calculating a signal proportional to velocity or acceleration from the signal is provided. The output of the calculation unit 1 is input to the comparison calculation unit 2. Easy to diagnose.

According to a sixth aspect of the present invention, in the invention according to the third to fifth aspects, a communication means is provided, and at least one of the signal related to the device or the reference signal is input from the communication means. It is something that is done. Flexible diagnostic conditions can be set.

According to a seventh aspect of the present invention, a calculation unit 1 for inputting a valve opening signal or an output pressure signal to the valve and calculating a signal proportional to the speed or acceleration of the signal.
And a comparison calculation unit 2 to which an output of the calculation unit 1 and a signal related to the setting signal of the valve are input. The comparison calculation unit 2 includes a signal proportional to the speed or acceleration and the setting signal. By comparing and calculating with a related signal, whether or not stick slip has occurred in the valve is diagnosed. No need for complicated statistical processing.

The invention according to claim 8 is the invention according to any one of claims 3 to 7, wherein the level of the velocity or acceleration signal and a predetermined threshold value is maintained for a predetermined time after the reference signal is changed. The diagnosis is made by comparison. Easy to diagnose.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings. FIG. 1 shows the configuration of a calculation unit that inputs a displacement signal and outputs a velocity or an acceleration. In FIG. 1, X0 is a displacement signal such as a valve opening signal, and 1 is an arithmetic unit to which the displacement signal X0 is input.

The computing unit 1 computes a signal proportional to velocity or acceleration from the input displacement signal X0 and outputs it as a signal Y0. These calculations are usually performed by digital signal processing. In the case of digital signal processing, the calculation for obtaining the signal proportional to the speed can be easily performed because only the difference between the previous displacement signal and the current displacement signal is calculated.
Since the signal proportional to the acceleration can be obtained by calculating the difference between the previous speed signal and the current speed signal, this can also be calculated easily.

FIG. 2 shows the configuration of the comparison calculation unit. In FIG. 2, X1-1 is, for example, a change rate signal or acceleration signal of the valve opening degree, and X1-2 is a reference signal such as a set point signal to the valve. Reference numeral 2 is a comparison operation unit to which these X1-1 and X1-2 signals are input.

The comparison operation section 2 performs comparison operation with the signal X1-1 with reference to the reference signal X1-2 and outputs the result as a signal Y1. The signal Y1 is output as an alarm signal, a discrete signal, a numerical signal, or a combination of these signals by a device that receives the signal.

FIG. 3 shows a configuration in which the arithmetic unit 1 and the comparison arithmetic unit 2 are combined. The same elements as those in FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted. X2-1 is a displacement signal such as valve opening. The computing unit 1 computes a signal proportional to the velocity or acceleration of displacement from this displacement signal X2-1 and outputs it as a signal Y2-1.

The output Y2-1 of the calculation unit 1 is input to the comparison calculation unit 2. A reference signal X2-2 such as a valve set point is input to the comparison calculation unit 2. The comparison calculation unit 2 performs a comparison calculation using the reference signal X2-2 as a reference, and outputs the result as a signal Y2-2.

FIG. 4 shows an example of the operation of the comparison calculation section 2. In Figure 4, X2-2 is the valve set point, X2
-1 is a valve opening signal. Set point at time t1
When X2-2 rises, the valve opening signal X2-1 starts changing with a slight delay. Y2-1 is a speed signal of the valve opening, which is a non-zero constant value while the valve opening is changing.

Yth is a threshold for diagnosis. The comparison calculation unit 2 compares the speed signal Y2-1 of the valve opening degree with the threshold value Yth for a predetermined time T. That is, the reference signal X2-2 is used as a time reference (starting point). Since the valve opening speed signal Y2-1 exceeds the threshold value Yth when the value is not zero during the time T, it is determined that the valve opening speed signal Y2-1 is operating normally.

X2-1 'in FIG. 4 is another example of the speed signal of the valve opening. In this case, the valve displacement speed is slowed because an abnormality has occurred in the valve. Therefore, the corresponding valve opening speed signal Y2-1 ′ becomes smaller than the threshold value Yth. Therefore, it is diagnosed as abnormal.

FIG. 5 shows an example in which stick slip has occurred. In FIG. 5, X2-2 is the set point of the valve, which rises at time t2. Therefore, the valve opening signal X2-1 changes at a constant speed with a slight delay. Y2-1 is a valve signal of the valve opening, and shows a constant value that is not zero while the valve opening signal is changing. Yth 'is a threshold for stick-slip diagnosis.

During a predetermined time T after the reference signal X2-2 rises, the speed signal Y2-1 is compared with the threshold value Yth '. Also in this case, the reference signal X2-2 is used as a time reference. Since the valve opening speed signal Y2-1 is smaller than this threshold value Yth ', it is determined to be normal.

X2-1 'is a valve opening signal when stick-slip occurs, and has a large rise and shows irregular movement. Y2-1 'is the speed signal of the valve opening. The comparison calculation unit 2 compares the valve opening speed signal Y2-1 ′ with the threshold value Yth ′ during the time T. At time t3, speed signal Y
Since 2-1 'exceeds the threshold value Yth', it is diagnosed that stick-slip has occurred.

As described above, by using the valve opening as the input signal to be operated and the valve set point signal as the reference input signal, the phenomenon that the valve response becomes abnormally slow by simple comparison operation and An abnormal phenomenon that responds rapidly by stick-slip can be detected.

Although the valve opening signal has been described in this embodiment, the present invention is not limited to this, and the input signal X2-1 and the reference signal X2-2 may be in any combination. .

For example, considering the positioner as the center, a valve opening signal, an output pressure signal to the valve, and a set point signal to the positioner can be combined. Also, focusing on the process controller built into the host system or field equipment, the flow rate value, pressure value, temperature value, liquid level value, set point to the controller,
The controller output signal, valve opening signal, and output pressure signal can be combined.

Furthermore, when the arithmetic function is implemented as a function block conforming to the Foundation Fieldbus standard, the output value of the function block of another device on the fieldbus was measured in-house. Since process values such as valve opening and output pressure signal can be selected in combination, more flexible diagnostic conditions can be set.

FIG. 6 shows an embodiment in a system including a field bus. In FIG. 6, 3 is a field bus and 4 is a process controller connected to the field bus 3. The process controller 4 measures a process value such as a valve opening degree and outputs a control signal.

Reference numeral 41 is a diagnostic device having the same configuration as in FIG.
A valve opening measured by the process controller 4 and a signal from another function block connected to the fieldbus 3 are input via the fieldbus 3. The diagnostic device 41 diagnoses the device based on these input values and outputs the result.

In such a configuration, by providing an open function block, it is possible to combine the devices in multiple vendors and perform optimum process diagnosis and valve diagnosis.

[0039]

As is apparent from the above description,
According to the present invention, the following effects can be expected. According to the first aspect of the present invention, there is provided a method for diagnosing whether or not a device is operating normally, which is related to a signal proportional to the speed or acceleration of a signal related to the device to be diagnosed and the device. By comparing and calculating with the reference signal, the device diagnoses whether or not the device is operating normally.

Since the diagnosis can be made only by comparing the input values, there is an effect that complicated statistical processing is unnecessary and the diagnosis can be performed at high speed. Further, there is an effect that even a CPU having a small processing capacity can be diagnosed at high speed.

According to a second aspect of the present invention, in the first aspect of the invention, the signal proportional to the velocity or the acceleration is compared with the threshold value for a predetermined time after the reference signal is changed. . Because you can diagnose only by comparing the levels,
There is an effect that diagnosis can be performed quickly and easily.

According to the third aspect of the present invention, there is provided a device diagnostic device for diagnosing whether the device is operating normally,
A signal related to the device is input, and a calculation unit 1 that calculates and outputs a signal proportional to the speed or acceleration of the signal is provided, and the device is diagnosed based on the output of the calculation unit 1. .

Since the velocity or the acceleration can be obtained by performing the difference calculation, there is an effect that the diagnosis can be performed at a high speed. Further, since complicated statistical processing is unnecessary, it is possible to diagnose even a CPU having a low processing capacity.

According to the fourth aspect of the present invention, there is provided a device diagnostic device for diagnosing whether the device is operating normally,
It has a comparison operation part 2 to which a signal proportional to the speed or acceleration of a signal related to this device and a reference signal related to the device are input, and this comparison operation part 2 and a signal proportional to the speed or acceleration A comparison operation is performed with a reference signal to diagnose whether the device is operating normally.

Since the diagnosis can be made only by comparing the input values and complicated statistical treatment is not required, there is an effect that the diagnosis can be performed at high speed. Further, since it is possible to diagnose even a CPU having a low processing capacity, it is possible to use a CPU with low power consumption, and it is possible to easily realize intrinsically safe explosion-proof.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, a signal relating to the equipment is input, and the arithmetic unit 1 for calculating a signal proportional to velocity or acceleration from this signal is provided. The output of the calculation unit 1 is input to the comparison calculation unit 2.

By calculating the velocity component or the acceleration component, there is an effect that diagnosis can be performed more easily. Further, since the speed / acceleration can be obtained by the difference calculation, there is an effect that a CPU having low processing capability can be used.

The invention according to claim 6 is the invention according to any one of claims 3 to 5, further comprising communication means for inputting at least one of a signal related to the device or the reference signal from the communication means. I decided to do it.

Since it is possible to make a diagnosis by using the process value of a remote place connected by the field bus, there is an effect that the diagnosis condition can be set more flexibly.

According to the seventh aspect of the present invention, the arithmetic unit 1 for inputting the valve opening signal or the output pressure signal to the valve and calculating a signal proportional to the speed or acceleration of the signal, and the arithmetic unit. 1 and a comparison calculation unit 2 to which a signal related to the valve setting signal is input,
The comparison calculation unit 2 compares the signal proportional to the speed or acceleration and the signal related to the setting signal to diagnose whether or not stick slip has occurred in the valve.

Since the stick-slip phenomenon of the valve can be diagnosed without using complicated processing such as statistical processing, there is an effect that the diagnosis can be performed at high speed. Further, since it is possible to make a diagnosis even with a CPU having a low processing capacity, it is possible to use a CPU with low power consumption, and it is possible to easily realize the intrinsically safe explosion-proof required for field devices.

According to the invention described in claim 8, in the invention described in claims 3 to 7, the level of the signal proportional to the velocity or acceleration and the level of the threshold value for a predetermined time after the change of the reference signal. I tried to compare. Since the diagnosis can be made only by comparing the levels, there is an effect that the diagnosis can be easily and quickly performed.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing an embodiment of the present invention.

FIG. 3 is a configuration diagram showing an embodiment of the present invention.

FIG. 4 is a diagram for explaining the effect of the present invention.

FIG. 5 is a diagram for explaining the effect of the present invention.

FIG. 6 is a configuration diagram showing another embodiment of the present invention.

FIG. 7 is a configuration diagram of a conventional stick-slip detection device.

[Explanation of symbols]

1 computing unit 2 Comparison calculation part 3 fieldbus 4 Process controller 41 Diagnostic device

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Claims (8)

[Claims] 1. A method for diagnosing a device for diagnosing whether the device is operating normally, in which a signal proportional to the speed or acceleration of a signal related to the device to be diagnosed and a reference signal related to the device are compared and calculated. Then, a method for diagnosing a device is characterized in that whether or not the device is operating normally is diagnosed. 2. The diagnosis is performed by comparing the level of the velocity or acceleration signal with a predetermined threshold value for a predetermined time after the reference signal has changed. How to diagnose equipment. 3. A device diagnostic device for diagnosing whether or not a device is operating normally, comprising a computing section for receiving a signal related to the device and computing and outputting a signal proportional to the speed or acceleration of the signal. A diagnostic device for a device, characterized in that the device is diagnosed on the basis of the output of the arithmetic unit. 4. A diagnostic apparatus for a device for diagnosing whether the device is operating normally, wherein a comparison operation in which a signal proportional to the velocity or acceleration of a signal related to the device and a reference signal related to the device are input. And comparing the signal proportional to the speed or acceleration with the reference signal by the comparison calculation unit to diagnose whether or not the device is operating normally. Equipment diagnostic equipment. 5. A signal relating to the device is input, and a calculation unit for calculating a signal proportional to velocity or acceleration from the signal is provided, and the output of the calculation unit is input to the comparison calculation unit. The diagnostic device for equipment according to claim 4, wherein 6. A communication means is provided, and at least one of the signal related to the device or the reference signal is inputted from the communication means.
A diagnostic device for a device according to claim 5. 7. An arithmetic unit for inputting a valve opening signal or an output pressure signal to the valve to calculate a signal proportional to the speed or acceleration of the signal, and an output of the arithmetic unit and a setting signal of the valve. A comparison calculation unit to which a related signal is input, the comparison calculation unit compares and calculates a signal proportional to the speed or acceleration and a signal related to the setting signal, and a stick slip occurs in the valve. A diagnostic device for equipment, which is characterized in that it is adapted to diagnose whether or not it is operating. 8. The diagnosis is performed by comparing the level of the velocity or acceleration signal with a predetermined threshold value for a predetermined time after the reference signal has changed. A diagnostic device for a device according to claim 7.