JP6163112B2 - Positioner - Google Patents

Description

  The present invention relates to a positioner that controls the opening of a valve so that the actual opening coincides with a set opening sent from a host device.

  Conventionally, as a positioner for controlling the opening degree of a valve, for example, there is one as shown in FIG. In the figure, 100 (100A) is a positioner, and 200 is a valve. The positioner 100A includes a signal current conversion unit 1, a control calculation unit 2, an electropneumatic conversion unit 3, and a valve opening degree detection unit 4.

  In this positioner 100A, the signal current converter 1 converts an input signal I indicating a set opening degree sent as a signal of 4 to 20 mA from the host device into a control signal Vo. The valve opening degree detection unit 4 detects the actual opening degree of the valve 200 and outputs an opening degree signal Vs indicating the detected actual opening degree. The control calculation unit 2 calculates a deviation between the control signal Vo from the signal current conversion unit 1 and the opening signal Vs from the valve opening detection unit 4, and drives an electric signal obtained by performing PID control calculation on the deviation. Output as signal Vd.

  The electropneumatic conversion unit 3 converts the drive signal Vd from the control calculation unit 2 into an output air pressure Po to the valve 200 and outputs it to the operating unit 201 of the valve 200. As a result, air of the air pressure Po flows into the diaphragm chamber in the operation device 201, and the opening degree of the valve in the valve body 202 is adjusted.

  In this positioner 100A, the actual opening degree of the valve 200 detected by the valve opening degree detection unit 4 is sent to the control calculation unit 2 as the opening degree signal Vs, thereby providing a control feedback signal for the control signal Vo. Therefore, it is very important in valve control to accurately read the opening signal Vs. The opening signal Vs is received by the receiving circuit, which is an electric circuit, in the control calculation unit 2, is subjected to A / D conversion, is taken into a CPU (Central Processing Unit), and is used as a control feedback signal.

JP-A-7-83203

  However, in the installation situation of on-site equipment such as a plant, various equipment such as a power source is in operation and various noises are generated, and the positioner 100A may be affected by the environment. As an effect thereof, when noise is applied to the valve opening degree detection unit 4 or the opening signal line Vs, the receiving circuit of the opening degree signal Vs malfunctions. For example, the output of the receiving circuit is the original opening degree signal. There is a case where the data is output with a shift slightly shifted from Vs and A / D converted.

  In this case, the positioner 100A cannot recognize the correct opening degree of the valve 200, and applies control feedback with an incorrect (shifted) opening signal Vs. As a result, the opening degree of the valve 200 is incorrect (shifted). ) Will cause adverse effects and losses on plant production.

For example, the input signal I changing in the range of 4 to 20 mA is 12 mA (50%), the control signal Vo = 50%, the valve opening Vs (original opening signal) = 75%, and reception of the result including noise When the error opening signal shifted by the circuit = 60%, the positioner 100A operates so that the error opening signal = 60% matches the control signal Vo = 50%, and the error opening signal is changed from 60% → When the operation is lowered to 50%, the valve opening Vs (original opening signal) = 75% is reduced by 10% and becomes 75% → 65%. As a result, with respect to the control signal Vo = 50%, the valve opening Vs (original opening signal) = 65%, which is stabilized here. Further, in the control calculation unit 2 , since the CPU recognizes that the control signal Vo = 50% and the erroneous opening signal = 50% match, the valve opening Vs (original opening signal) = 65. % Is not noticed.

  In the first example of Patent Document 1, the output air pressure Po from the electropneumatic converter 3 is converted into a pressure signal Va, and an abnormality is determined by comparing the pressure signal Va and the opening signal Vs. ing. In the second example of Patent Document 1, an abnormality is determined by comparing the opening signal Vs and the drive signal Vd. Further, in the third example of Patent Document 1, an abnormality is determined by comparing the opening signal Vs and the control signal Vo. However, in such a method, in any example, since only two signals are compared, a case where an abnormality is not noticed may be missed.

  For example, in the second example of Patent Document 1, even though the opening signal Vs and the drive signal Vd match and control seems to be performed normally, the control is actually performed with a wrong opening. In the third example of Patent Document 1, it seems that the control signal Vo and the opening degree signal Vs coincide with each other and the control is normally performed. However, an abnormality such as the fact that the control is actually performed at the wrong opening degree is overlooked.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a positioner capable of not overlooking a case in which an abnormality is not noticed.

In order to achieve such an object, the present invention provides a control signal indicating a set opening degree in a positioner that controls the opening degree of a valve so that the actual opening degree coincides with the set opening degree sent from a host device. A control calculation unit that generates a drive signal corresponding to the deviation between the control signal and the opening signal, and an output signal from the control calculation unit to the valve. An electropneumatic converter that converts to air pressure, a valve opening detector that detects the current opening of the valve and uses it as an opening signal to the control calculator, and a value and opening signal expressed as a percentage indicated by the control signal The value indicated by the percentage indicated by the drive signal and the value indicated by the percentage indicated by the drive signal are compared, and if the value indicated by at least one of the signals is different from the value indicated by the other signal, the abnormality is determined to be abnormal And a diagnostic unit.

According to the present invention, at least one of the value (%) indicated by the control signal (Vo), the value (%) indicated by the opening signal (Vs), and the value (%) indicated by the drive signal (Vd). When the value indicated by one signal is different from the value indicated by the other signal, it is determined as abnormal. That is, if the value (%) indicated by the control signal (Vo), the value (%) indicated by the opening signal (Vs), and the value (%) indicated by the drive signal (Vd) match, it is determined as normal. Otherwise, it is judged abnormal. Thereby, for example, even if the value (%) indicated by the control signal (Vo) matches the value (%) indicated by the opening degree signal (Vs) and the control seems to be performed normally, Actually, an abnormality such that the control is performed with an incorrect opening, or the value (%) indicated by the opening signal (Vs) matches the value (%) indicated by the drive signal (Vd). Even if it seems that the control is normally performed, an abnormality such as the fact that the control is actually performed with the wrong opening is not missed.

In the present invention, the abnormality diagnosis unit compares the value (%) indicated by the control signal (Vo) with the value (%) indicated by the opening signal (Vs) and the value (%) indicated by the drive signal (Vd). In this case, the abnormality is determined. When the abnormality is determined, the value (%) indicated by the control signal (Vo) and the value (%) indicated by the opening signal (Vs) are combined with the determination result indicating the abnormality. And the value (%) indicated by the drive signal (Vd) may be notified to the host device or the like. The comparison result of the value (%) indicated by the control signal (Vo), the value (%) indicated by the opening signal (Vs), and the value (%) indicated by the drive signal (Vd) is useful for identifying an abnormal location. Become.

According to the present invention, the value (%) indicated by the percentage indicated by the control signal, the value (%) indicated by the percentage indicated by the opening signal, and the value (%) indicated by the percentage indicated by the drive signal are obtained. In comparison, when the value indicated by at least one of the signals is different from the value indicated by the other signal, it is determined that there is an abnormality, so that it is possible to avoid missing a case where the abnormality is not noticed.

It is a block diagram which shows the principal part of one Embodiment of the positioner which concerns on this invention. It is a flowchart for demonstrating in detail the function which the abnormality diagnosis part in this positioner has. It is a figure which shows an example of the comparison result of the control signal Vo, the opening degree signal Vs, and the drive signal Vd with the determination result. It is a figure which shows the structure of the principal part of the conventional positioner.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a main part of an embodiment of a positioner according to the present invention. 4, the same reference numerals as those in FIG. 4 denote the same or equivalent components as those described with reference to FIG.

  In the positioner 100 (100B) of the present embodiment, an abnormality diagnosis unit 5 is provided in addition to the basic configuration of the signal current conversion unit 1, the control calculation unit 2, the electropneumatic conversion unit 3 and the valve opening degree detection unit 4, A control signal Vo, an opening signal Vs, and a drive signal Vd are branched and given to the abnormality diagnosis unit 5.

  The abnormality diagnosis unit 5 compares the input control signal Vo, the opening degree signal Vs, and the drive signal Vd, and determines that an abnormality is present when the value indicated by at least one of the signals is different from the value indicated by the other signals. In addition to the determination result indicating the abnormality, the comparison result of the control signal Vo, the opening degree signal Vs, and the drive signal Vd is notified to the host device.

  Note that the functions of the control calculation unit 2 and the abnormality diagnosis unit 5 in the positioner 100B are realized by hardware including a processor and a storage device, and a program that realizes various functions in cooperation with these hardware.

  The functions of the abnormality diagnosis unit 5 will be described in more detail with reference to the flowchart shown in FIG.

  The abnormality diagnosis unit 5 monitors the control signal Vo, and if the control signal Vo remains unchanged for a predetermined time T or longer (NO in step S101, YES in step S103), the opening degree signal Vs and the drive signal Vd are obtained. The control signal Vo, the opening signal Vs, and the drive signal Vd are compared (step S105).

  In addition, when the control signal Vo changes during monitoring of the control signal Vo (YES in step S101), the abnormality diagnosis unit 5 waits for a predetermined settling time TA to elapse (YES in step S102). After confirming that the state in which the signal Vo remains unchanged for a predetermined time T or longer (YES in step S103), the process proceeds to steps S104 and S105, and the control signal Vo, the opening signal Vs, and the drive signal Vd are compared. .

Here, if the control signal Vo, the opening signal Vs, and the drive signal Vd match (YES in step S105), that is, the value (%) indicated by the percentage indicated by the control signal Vo and the opening signal Vs indicate. If the value (%) indicated by the percentage matches the value (%) indicated by the percentage indicated by the drive signal Vd , the abnormality diagnosis unit 5 determines that the control state is normal (step S106). Returning to step S101, the same operation as described above is repeated.

  On the other hand, if the control signal Vo, the opening signal Vs, and the drive signal Vd do not match (NO in step S105), that is, the value indicated by at least one of the signals is different from the value indicated by the other signals. Then, it is determined that the control state is abnormal (step S107), and the comparison result of the control signal Vo, the opening signal Vs, and the drive signal Vd is notified to the host device together with the determination result indicating that the control is abnormal. (Step S108).

That is, as shown in FIG. 3 as an example, if the control signal Vo, the opening signal Vs, and the drive signal Vd match (case I), it is determined to be normal. On the other hand, if the control signal Vo, the opening degree signal Vs, and the drive signal Vd are all different (case II), it is determined that there is an abnormality. Even if the control signal Vo and the drive signal Vd match, if the opening signal Vs does not match (Case III), it is determined that there is an abnormality, and the opening signal Vs and the drive signal Vd match. However, if the control signal Vo does not match (case IV), it is determined that there is an abnormality, and even if the control signal Vo and the opening signal Vs match, the drive signal Vd does not match (case V). ).

  Thereby, for example, even if the control signal Vo and the opening signal Vs coincide with each other and the control seems to be performed normally, the control is actually performed with the wrong opening. Even if the opening signal Vs and the drive signal Vd coincide with each other and the control seems to be performed normally, the control is actually performed with the wrong opening. An abnormality or an abnormality such that the control signal Vo and the drive signal Vd coincide with each other and the control seems to be performed normally, but the control is actually performed with the wrong opening degree. You will never miss.

  In addition, the abnormality diagnosis unit 5 notifies the host device of the comparison result of the control signal Vo, the opening degree signal Vs, and the drive signal Vd together with the determination result indicating that there is an abnormality. Helps to identify abnormal locations.

  For example, in case III, an abnormality of the valve 200, an abnormality of the valve opening degree detection unit 4 (an opening degree sensor), and the like are considered as causes. In the case of Case IV, the cause may be the case where the control calculation unit 2 (control calculation circuit) and the valve opening degree detection unit 4 (opening sensor) are broken in conjunction with each other. In case V, noise may be superimposed on the opening signal Vs, the valve opening detector 4 (opening sensor) may be abnormal, or the control arithmetic unit 2 (control arithmetic circuit) may be abnormal.

  In the host device, the operator can specify an abnormal part, though roughly, using a comparison result of the control signal Vo, the opening degree signal Vs, and the drive signal Vd notified from the positioner 100B as a hint.

  In this way, in this embodiment, the soundness of the valve control is monitored, and if an abnormality is found in the valve opening, it is immediately transmitted to the operator to minimize the serious loss of the plant. It becomes possible to suppress to.

  In the above-described embodiment, the abnormality diagnosis unit 5 notifies the host device that an abnormality has occurred. However, a separate air system is provided for the valve 200 so that the valve 200 is forcibly turned off. You may make it do. Means for notifying the host device of an abnormality from the abnormality diagnosis unit 5 is a communication signal such as HART (Highway Addressable Remote Transducer), FF (Fieldbus Foundation), and SFN (Single Frequency Network) in addition to a current signal of 4 to 20 mA. , DO signal, etc.

[Extension of the embodiment]
The present invention has been described above with reference to the embodiment. However, the present invention is not limited to the above embodiment. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the technical idea of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Signal current conversion part, 2 ... Control calculating part, 3 ... Electropneumatic conversion part, 4 ... Valve opening degree detection part, 5 ... Abnormality diagnosis part, 100 (100B) ... Positioner, 200 ... Valve, 201 ... Actuator, 202 ... Valve body.

Claims (2)

In a positioner that controls the valve opening so that the actual opening matches the set opening sent from the host device,
A control arithmetic unit that receives the control signal indicating the set opening and the opening signal indicating the actual opening of the valve, and generates a drive signal corresponding to the deviation between the control signal and the opening signal;
An electropneumatic conversion unit that converts a drive signal from the control calculation unit into an output air pressure to the valve;
A valve opening degree detection unit that detects the current opening degree of the valve and sets the opening degree signal to the control calculation unit;
A value represented by the percentage indicated by the control signal, a value represented by the percentage indicated by the opening signal, and a value indicated by the percentage indicated by the drive signal, and a value indicated by at least one of the signals A positioner comprising: an abnormality diagnosing unit that determines that an abnormality occurs when the value differs from a value indicated by another signal. The positioner as claimed in claim 1,
The abnormality diagnosis unit
When it is determined that there is an abnormality, together with the determination result indicating that there is an abnormality, the value represented by the percentage indicated by the control signal, the value indicated by the percentage indicated by the opening signal, and the percentage indicated by the drive signal. The positioner is characterized by notifying the result of comparison with the measured value .

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