JPH05341802A - Process controller - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to obtain a process control device capable of continuing stable control by a normal sequence that remains even when a certain sequence of tripled control devices fails. Is. A process control device according to the present invention is provided with a diagnostic circuit for detecting an abnormality in each of the tripled control devices, and when an abnormality is detected by this diagnostic circuit, a corresponding abnormal current amplifier to a coil is connected to the coil. A means for disconnecting the current output circuit is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplexed process control device for controlling a process.

[0002]

2. Description of the Related Art In a process control device used in a plant requiring high reliability such as a nuclear power plant, it is general that a part requiring particularly high reliability is tripled. This is because even if a failure occurs in one series of the triplicated system, control can be continued by the remaining series, and it is possible to prevent a single failure from affecting the operation of the plant.

As a control device of this kind, there is a triple coil current control device shown in FIG. Based on the tripled control commands v _{1a to} v _1c from the upstream side control device, the tripled current amplifiers _{1 a} to ₁ c are three-system coils 2 a.
Output current to ~ 2c.

A servo valve for controlling the opening degree of the turbine steam valve shown in FIG. 5 is a control target using the triple coil. The tripled coil is wound around the torque motor 12 of the servo valve. Torque motor 13
Is placed in the magnetic field formed by the fixed magnet (N) 10 and the fixed magnet (S) 11 with the intersection 13 as the center, and the polarity and strength of the magnetic field generated in the torque motor itself by the coil currents i _{1a to} i _1c. That is, it rotates about the fulcrum 13 depending on the direction and strength of the coil current. A jet nozzle 14 is connected to the torque motor 13,
Supplies the high pressure control oil supplied from above to the left side of the spool 15 when the torque motor 13 operates clockwise, and supplies the high pressure control oil to the right side of the spool 15 when the torque motor 13 operates counterclockwise. Supply. When the high pressure control oil is supplied to the left side of the spool 15, the spool 15 moves to the right side, and this movement causes the port A16 and the port B1 to move.
The 7 are connected. Port A16 is connected to the drain line of high pressure control oil, and port B17 is connected to the oil cylinder of the turbine steam valve. Therefore, the connection between port A16 and port B17 causes the oil in the oil cylinder to be discharged to the drain line and the turbine steam valve. Operates in the closing direction.

When high-pressure control oil is supplied to the right side of the spool 15, the spool 15 moves to the left side, and this movement connects the ports B17 and C18. Since the port C18 is connected to the high pressure control oil supply line, oil is supplied to the oil cylinder via the port B17 by this operation, so that the turbine steam valve operates in the opening direction. As described above, the torque motor 13 is controlled by the electric currents of the triple coils 2a to 2c, and finally the opening degree of the turbine steam valve is controlled.

Next, a case where a failure occurs in the control device will be described. The torque motor 13 is controlled by a driving force proportional to the total current of the triple coils 2a to 2c, and the relationship between the total coil current and the control command is as follows.

The gain of each current amplifier 1a-1c is K ₁ ,
K _2, K _3, also from the control device input signal v _1a to v _1c is that is triplexed upstream of the current amplifier, 3 system because the same value is _{entered, v 1a = v 2a = v} 3a ==

[0008]

## EQU1 ## i _1a = K ₁ v i _1b = K ₂ v i _1c = K ₃ v Therefore, if the coil total current proportional to the driving force of the torque motor 13 is i,

[0009]

## EQU2 ## i = i _1a + i _1b + i _1c = K ₁ v + K ₂ v + K ₃ v = (K ₁ + K ₂ + K ₃ ) v, and the torque motor 13 is controlled in proportion to the control command v. Here, considering the case where the A-system coil 2a is broken or the output of the A-system current amplifier 1a is lost, i _1a = 0 and the total coil current is

[0010]

Equation 3] _{i = i 1b + i 1c =} K 2 v + K 3 v = (K 2 + K 3) v , and the coil total current based on the control command v, that is, capable of proportional control of the torque motor driving force. Also, 2
Similarly, proportional control of the total coil current is possible even when the coil disconnection of the system or the loss of the current amplifier output is taken into consideration. The control circuit of FIG. Alternatively, it is possible to continue the control of the torque motor 13 based on the control command v for failures up to the second system.

[0011]

When the current of the triple coil of FIG. 5 is controlled by the triple control device of FIG. 4, the coil breakage of the 1-system or 2-system as described above or It was described that the torque motor can be controlled based on the control command for the output loss of the current amplifier. Next, consider a failure mode such as saturation of the power amplifier output in the positive or negative direction. _{Assuming that} the output is saturated at I _x due to the failure of the current amplifier A _1a , the relationship between the control command v and the coil total current i is as follows.

[0012]

[Equation 4] There is no problem because the torque motor 13 is controlled based on the control command v, but if it is desired to control the total coil merging in the forward direction by the control command v, (K ₂ + K ₃ )
When + I _x <0, or when it is desired to control the coil current in the negative direction, (K ₂ + K ₃ ) v + I _x > 0, and the output of the current amplifier A _1a is saturated with I _x ,
The torque motor 13 operates in the direction opposite to the control command v, which makes stable control of the torque motor 13 impossible.

It is an object of the present invention to provide a process control device capable of continuing stable control by a normal sequence remaining even if a certain sequence of such triple control devices fails. ..

[0014]

SUMMARY OF THE INVENTION The present invention is provided with a diagnostic circuit for detecting an anomaly in each of the multiplexed control devices, and when the diagnostic circuit detects an anomaly, the current from the current amplifier to the coil of the corresponding abnormal system is detected. A means for disconnecting the output circuit is provided.

[0015]

When a failure occurs in the triple control device that controls the current of the triple coil, the circuit that detects the failure separates the failed series and normalizes the remaining normal series. Continue control.

[0016]

1 shows the structure of a process control apparatus according to an embodiment of the present invention, in which control commands v _1a , v _1b , v _1c from a control apparatus on the upstream side are supplied to a current amplifier 1 respectively.
a, 1b, 1c, and current amplifiers 1a, 1b, 1
c is a current proportional to the input signal to the coils 2a, 2b, 2c
To control the current flowing through each coil.

Each series of the triplicated control device includes:
Diagnostic devices 3a, 3b, 3c are provided respectively,
When the self-diagnosis of each series is performed and an abnormality is detected in the corresponding series, the contacts 4a, 4b, 4c of the corresponding series are disconnected, and the circuit for supplying a current from the current amplifier to the coil is excluded. FIG. 2 shows an example of an abnormality detecting method in the diagnostic devices 3a, 3b, 3c.

In the diagnostic device 3a of FIG. 2, the comparator 5
The provided performs comparison between the input signal v _1a and the output signal i _1a of the current amplifier A _1a. Normally, the gain of the current amplifier A is constant and the input signal v _1a and the output signal i _1a are in a proportional relationship. However, in the comparator 5, when the output signal i _1a is not in a proportional relationship with the input signal v _1a , It is judged that the current amplifier 1a is abnormal, and the contact 4a is opened via the OR circuit 7. The comparator 6 compares the current output to the coil 3a with the return current from the coil 3 to detect a short circuit or a ground fault in the coil 3a and open the contact 4a via the OR circuit 7.
Other diagnostic methods in the diagnostic device 3a include detection of abnormally high or low output of the current amplifier 1a. As described above, the coil total current i is normally controlled by the tripled current amplifiers 1a, 1b, 1c based on the control command v as follows.

[0019]

## EQU00005 ## i = i _1a + i _1b + i _1c = K ₁ v + K ₂ v + K ₃ v = (K ₁ + K ₂ + K ₃ ) v

Here, when an abnormality occurs in the tripled control device A series, the abnormality is detected by the diagnostic circuit 3a, the contact 4a is opened, and the current output circuit to the coil 2a is excluded. The total current i is

[0021]

[Equation 6] i = i _1a + i _1b + i _1c = 0 + K ₂ v + K ₃ v = (K ₂ + K ₃ ) v, and even if an abnormality occurs in one series, the proportionality of the coil total current i based on the control command v is surely achieved. It becomes possible to control. Further, when an abnormality occurs in the control devices B and C, the diagnostic circuits 3a and 3b operate similarly,

[0022]

[Equation 7] i = i _1a + i _1b + i _1c = 0 + 0 + K ₃ v = K ₃ v, and proportional control of the coil total current i based on the control command v can be reliably performed even when two series are abnormal. ..

Therefore, according to the present invention, even if abnormality occurs in one or two series of tripled current amplifiers and coils, stable control can be continued by excluding the circuit in which abnormality has occurred. Becomes FIG. 3 shows another embodiment of the process control device according to the present invention.

In FIG. 3, in the intermediate value selection circuit 20, 3
The intermediate value of the currents i _1a , i _1b , i _1c flowing through the doubled coils 2a, 2b, 2c is selected, and the intermediate value of the deviation calculator 21 is output. The deviation calculator 21 calculates the deviation between the intermediate value and the coil current of each series, and outputs it to the comparator 22. In the comparator 22, when the input deviation exceeds the specified value, the contact 5a provided between the current amplifier 1a and the coil 2a is opened to cut off the current to the coil.

When the deviation between the intermediate value of the coil currents of the three systems and the coil current of any one series becomes large by such means, the series is regarded as abnormal, and the circuits of the series regarded as abnormal are excluded. To do.

[0026]

As described above, according to the present invention, it is possible to reliably detect one series of abnormalities, and by excluding the circuit concerned by abnormality detection, as in the above-described embodiment,
It is possible to continue stable control with respect to one series of abnormalities.

[Brief description of drawings]

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

FIG. 2 is a detailed diagram of a diagnostic circuit of the present invention.

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

FIG. 4 is a circuit configuration diagram showing a conventional example.

FIG. 5 is an explanatory diagram of a coil servo valve that is a control target.

[Explanation of symbols]

 1 ... Current amplifier 2 ... Coil 3 ... Diagnostic circuit 4 ... Contact point 5 ... Comparator 6 ... Comparator 7 ... OR circuit 10 ... Fixed magnet N 11 ... Fixed magnet S 12 ... Torque motor 13 ... Support point 14 ... Jet nozzle 15 ... Spool 16 ... Port A 17 ... Port B 18 ... Port C 20 ... Intermediate value selection circuit 21 ... Deviation calculation circuit 22 ... Comparator

Claims (4)

[Claims] 1. A process control device comprising a tripled coil and a tripled current amplifier for controlling a current flowing through the tripled coil, wherein the tripled current is used. A process control device comprising: a diagnostic circuit for detecting an abnormality in an amplifier and a coil; and means for disconnecting a current amplifier diagnosed as abnormal by the diagnostic circuit. 2. The process control device according to claim 1, further comprising means for detecting an abnormality of the current amplifier by comparing an input signal and an output signal of the current amplifier as a diagnostic circuit. 3. The process control device according to claim 1, wherein a means for detecting an abnormality of the coil is provided as a diagnostic circuit by comparing an input current and an output current of the coil. 4. A process control device comprising a tripled coil and a tripled current amplifier for controlling a current flowing through the tripled coil, wherein each tripled coil is provided. Means for calculating the intermediate value of the current flowing through the coil is provided, and by comparing the calculated intermediate value of the coil current with the current value of each coil, each abnormality of each tripled series is detected, and the abnormality is detected. A process control device comprising means for disconnecting a current inlet to a series coil.