Control method for avoiding equipment maloperation caused by faults of controller or clamping piece

Abstract

The invention relates to the field of industrial automatic control, in particular to a control method for avoiding equipment maloperation caused by faults of a controller or a clamping piece. The control method comprises the steps that in the controller, self negation is carried out on a closing instruction obtained through front logic calculation, and the closing instruction serves as an opening instruction; performing double-0 or double-1 judgment by taking the two instructions as intermediate variables, and finally outputting a switch instruction by an output function block when no double-0 or double-1 fault is confirmed; if it is judged that the double-0 or double-1 fault phenomenon exists, the output function block outputs a normal value of the last moment as a final switching instruction; the switch instructions are all connected to the terminal module, the terminal module sends control signals to corresponding main contacts of the bistable magnetic latching relay through hard wiring, the S end and the R end of the bistable magnetic latching relay correspond to the opening instruction and the closing instruction of the valve respectively, and when any end receives the instruction, the valve is opened and closed. And the bistable magnetic latching relay realizes opening and closing of the valve according to the corresponding switching state. According to the invention, it can be ensured that the solenoid valve is maintained in a power-on or power-off state, the risk of equipment misoperation caused by signal interruption is effectively avoided, and the safety of equipment and a unit is ensured.

Description

Technical Field

[0001] The present invention relates to the field of industrial automatic control, and in particular to a control method for preventing equipment from malfunctioning due to a controller or a card failure. Background Art

[0002] In the field of industrial automation, pneumatic valves, pumps and other process equipment can start, stop or switch operations by receiving single command switch signals. However, for large equipment such as pumps and fans, if their control systems are not equipped with electrical cabinets, they need to rely on advanced control platforms such as DCS (distributed control systems) or PLC (programmable logic controllers) to provide continuous long command signals. Specifically, when the signal is set to 1 and maintained, the device starts; and when the signal returns to zero, that is, reset to 0, the device stops running. This mechanism also applies to pneumatic valves with solenoid valves, especially switch valves. The power on and off of the solenoid valve directly determines the switch state of the valve.

[0003] However, this control method has potential risks. Once the controller or DO (digital output) card or terminal card fails, it may cause long signal loss, thus causing abnormal operation of the device. For example, the test results of the controller based on the HOLLiAS_MACS V5 platform after the failure are as follows: Figure 1 As shown in the figure, although the DO signal can be self-maintained at the moment of fault, there will be a short interruption of the DO signal when the controller restarts. This phenomenon may cause abnormal operation of equipment that relies on a single command signal, such as pumps or valves.

[0004] Taking the siphon destroyer valve in a nuclear power plant as an example, its working principle and control logic are particularly important for the safety of the unit. The key control components of the siphon destroyer valve include a filter pressure reducing valve, a two-position three-way solenoid valve, and a quick exhaust valve. In order to meet the process requirements, the siphon destroyer valve must reach the maximum opening state within 0.4 seconds. For this reason, three quick exhaust valves are designed to ensure that the valve opening speed meets the requirements. In addition, considering the fail-safe design, the siphon destroyer valve should automatically open in the case of "three breaks" (gas, power, and signal). Therefore, during normal operation, the solenoid valve continues to receive a long signal from the DCS and remains energized. After being filtered, the compressed air enters the valve membrane cavity through the solenoid valve and the quick exhaust valve, compressing the spring and causing the valve stem to close the valve. Once the solenoid valve loses power and the gas supply is interrupted, the gas in the valve membrane cavity is quickly emptied through the quick exhaust valve, and the valve opens quickly under the action of the spring.

[0005] Therefore, if the controller or DO card controlling the siphon breaking valve fails, the valve will open abnormally, triggering a chain reaction, which may cause the unit to shut down or significantly reduce power, seriously interfering with the normal operation of the unit. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a control method to avoid equipment malfunction due to controller or card failure, which can ensure that the solenoid valve remains in an energized or de-energized state, effectively avoid the risk of equipment malfunction caused by signal interruption, and ensure the safety of the equipment and the unit.

[0007] The present invention provides a control method for preventing malfunction of equipment due to a controller or card failure, comprising the following steps:

[0008] In the controller, the closing instruction obtained by the preceding logic calculation is self-inverted and used as the opening instruction;

[0009] The two instructions are used as intermediate variables to perform double 0 or double 1 judgment. When it is confirmed that there is no double 0 or double 1 fault, the output function block finally outputs the switch instruction; if it is determined that there is a double 0 or double 1 fault phenomenon, the output function block outputs the normal value of the previous moment as the final switch instruction;

[0010] The switch instructions are all connected to the terminal module, and the terminal module sends the control signal to the corresponding main contact of the bistable magnetic latching relay through hard wiring. The S end and R end of the bistable magnetic latching relay correspond to the opening instruction and closing instruction of the valve respectively. When either end receives the instruction, the bistable magnetic latching relay switches the state accordingly to realize the opening and closing of the valve.

[0011] In a specific embodiment of the present invention, the controller transmits the switch instruction signal to the DO module through the backplane and then transmits the control signal to the terminal module through the threshold cable.

[0012] In a specific embodiment of the present invention, the DO module includes two DO channels.

[0013] In a specific embodiment of the present invention, the switch instruction is connected to the terminal module through two DO channels respectively, the opening instruction is connected to the terminal channel through the first DO channel, and the closing instruction is connected to the terminal channel through the second DO channel.

[0014] In a specific embodiment of the present invention, when the solid-state relay access signal of the first DO channel is 0, the solid-state relay of the second DO channel is activated, and its auxiliary contact is closed;

[0015] When the solid-state relay of the first DO channel is activated by the access signal being 1, its auxiliary contact is closed, and the solid-state relay of the second DO channel is in an inactive state.

[0016] In a specific implementation of the present invention, the close instruction and the open instruction obtained by self-negation thereof are a pair of mutually exclusive open and close instructions.

[0017] In a specific embodiment of the present invention, after receiving an instruction, the bistable magnetic latching relay maintains the state until receiving an opposite instruction, without the need for continuous current maintenance.

[0018] Compared with the prior art, the control method of the present invention for avoiding malfunction of equipment due to controller or card failure has the following beneficial effects:

[0019] (1) The concept of dual-instruction mutual exclusion is introduced, that is, the closing instruction obtained by the preceding logic calculation is self-inverted as the opening instruction, forming a pair of mutually exclusive "open" and "close" instructions. At the same time, the integrity of these two instructions is monitored through the double 0 double 1 judgment mechanism to ensure that the switch instruction is output only when there is no double 0 / 1 fault. The dual instruction mechanism increases the redundancy of the system, avoids malfunctions caused by the failure of a single instruction, and improves reliability. At the same time, the double 0 double 1 judgment can quickly identify abnormal conditions of the instruction system and prevent the output of incorrect switch instructions in a faulty state.

[0020] (2) A bistable magnetic latching relay is used, which has two stable control states, corresponding to the opening and closing commands of the valve. After receiving a command, this relay can maintain the state until receiving the opposite command, without the need for continuous current maintenance. When the controller or DO card fails and causes the command to be lost, the SR bistable magnetic latching relay can maintain the current state to prevent the solenoid valve from accidentally switching, thereby avoiding malfunction of the equipment and enhancing fault tolerance.

[0021] (3) Furthermore, two DO channels are used, corresponding to the "on" and "off" instructions respectively. This design allows each instruction to have an independent transmission path, improving the independence and reliability of the system. The dual DO channel design means that the transmission of the "on" and "off" instructions no longer relies on a single path, enhancing the independence of each part of the system, reducing the risk of fault propagation, and improving system independence. When a problem occurs in the system, the dual DO channel design makes troubleshooting more intuitive, can locate the problem more quickly, shorten maintenance time, and simplify troubleshooting. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Indicates the self-reset phenomenon of DO signal due to controller failure;

[0023] Figure 2 Represents the original control loop block diagram;

[0024] Figure 3 A simplified control logic diagram of the present invention is shown;

[0025] Figure 4 A diagram showing the wiring and power supply circuit of the terminal module of the present invention;

[0026] In the figure, 11, 12, 14, 21, 22, and 24 represent the wiring terminals of the relay auxiliary contacts. DETAILED DESCRIPTION

[0027] In order to further understand the present invention, the embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the present invention.

[0028] The original control method is briefly described by taking the control of pneumatic switch valve on DCS platform as an example: Figure 2 First, the controller completes the logic operation inside, and then transmits the valve closing signal to the DO (digital output) module via the cage backplane bus. The DO module then transmits this signal to the terminal module through a prefabricated cable. Next, the terminal module sends the control signal to the corresponding relay main contact through hard wiring to energize it. At this time, the auxiliary contact of the relay is activated and switched to the 14 / 24 terminal position, thereby conducting the 48V power supply to the solenoid valve to realize the control of the pneumatic switch valve.

[0029] In order to avoid the loss of DO signal caused by the failure of the controller or DO card and enhance the reliability and fault tolerance of the system, the following technical scheme is formulated: first, the logic optimization is carried out, and the closing instruction obtained by the pre-logic calculation is self-inverted as the opening instruction; then the above two instructions are used as intermediate variables for double 0 double 1 judgment. When it is confirmed that there is no double 0 / 1 fault, the output function block finally outputs the switch instruction. If it is judged that there is a double 0 / 1 fault phenomenon, the output function block outputs the normal value of the previous moment as the final switch instruction. The next step is to connect the switch instructions to the terminal module, that is, the original method needs to occupy one DO channel, and now two DO channels are required, corresponding to the opening instruction and the closing instruction respectively; finally, the relay in the system is changed to an SR type bistable magnetic latching relay, which has two stable control states-S end and R end, corresponding to the opening and closing instructions of the valve respectively. When either end receives the instruction, the relay will switch the state accordingly without the need for continuous current to maintain the state, thereby enhancing the stability and fault tolerance of the system.

[0030] In order to further understand the present invention, the control method provided by the present invention to avoid malfunction of the equipment due to controller or card failure is described in detail below in conjunction with the embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0031] Example 1

[0032] Working condition 1: Valve open

[0033] First, if Figure 3 As shown, the pre-logic undergoes a series of operations ( Figure 3Only a simple illustration of the pre-logic is given), the output of the logic AND gate is 0, that is, at this time, the intermediate variable of the valve closing instruction = 0, and after the inversion operation, the intermediate variable of the valve opening instruction = 1;

[0034] Judge the switch command double 0 / 1. At this time, the closing command is 0 and the opening command is 1. There is no double 0 / 1 fault;

[0035] The above switch command signal is transmitted from the controller to the DO module through the backplane bus and then to the terminal module through the prefabricated cable;

[0036] Connect the valve closing command signal to the first DO channel, and the valve opening command signal to the second DO channel. At this time, the solid-state relay of the first DO channel of the terminal module remains in an inactive state because the access signal is 0; the solid-state relay of the second DO channel is activated, and its auxiliary contacts are closed;

[0037] The R reset coil circuit of the bistable magnetic latching relay is turned on, the R terminal is activated, the auxiliary contact switching switch of the relay keeps 11 and 12, 21 and 22 closed, the power supply circuit of the solenoid valve is disconnected, the gas circuit is cut off, and the valve is opened under the action of the spring force.

[0038] Example 2

[0039] Working condition 2: Valve closed

[0040] first, Figure 3 The output of the logic AND gate is 1, that is, at this time, the intermediate variable of the valve closing instruction = 1. After the inversion operation, the intermediate variable of the valve opening instruction = 0;

[0041] Judge the switch command double 0 / 1. At this time, the closing command is 1 and the opening command is 0. There is no double 0 / 1 fault;

[0042] The above switch command signal is transmitted from the controller to the DO module through the backplane bus and then to the terminal module through the prefabricated cable;

[0043] The valve closing command signal is connected to the first DO channel, and the valve opening command signal is connected to the second DO channel. At this time, the solid-state relay of the first DO channel of the terminal module is activated because the access signal is "1", and its auxiliary contact is closed; the solid-state relay of the second DO channel is in an inactive state;

[0044] The R-end coil circuit of the bistable magnetic latching relay is open, and the coil is not energized. The S-position coil circuit is connected, the coil is energized, and the auxiliary contact switching switch is actuated, so that 11 and 14, 21 and 24 are closed, the solenoid valve power supply circuit is connected, the gas circuit is opened, and the compressed air enters the membrane cavity to overcome the spring force and close the valve.

[0045] Example 3

[0046] Condition 3: Valve response when the controller or DO card fails

[0047] First, after the controller fails, once it resets itself, the DO signal will be Figure 1 As shown, it is lost for a short time. After the DO card fails, the DO signal cannot be output normally. In short, the above faults will cause the solid-state relays of the first DO channel and the second DO channel of the terminal module to become inactive at the same time;

[0048] Assume that the last moment is the valve open state of working condition 1, that is, the original first DO channel is silent and the second DO channel is activated. At this time, the second DO channel changes from the activated state to the silent state due to the above fault, and the R end coil loses power. However, based on the magnetic holding function of the relay, its auxiliary contacts can still ensure that 11 and 12, 21 and 22 are closed, thereby ensuring that the solenoid valve power supply circuit is disconnected, the gas circuit is cut off, and the valve is opened under the action of the spring force;

[0049] Assume that the last moment is the valve closed state of working condition 1, that is, the original first DO channel is activated and the second DO channel is silent. At this time, the first DO channel changes from the activated state to the inactivated state due to the above fault, and the S-end coil loses power. However, based on the magnetic holding function of the relay, its auxiliary contacts can still ensure that 11 and 14, 21 and 24 are closed, thereby ensuring that the solenoid valve power supply circuit is turned on, the gas circuit is opened, and the compressed air enters the membrane cavity to overcome the spring force to close the valve.

[0050] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0051] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for avoiding malfunction of equipment due to controller or card failure, characterized in that: The following steps are involved: In the controller, the closing instruction obtained by the preceding logic calculation is self-inverted and used as the opening instruction; The two instructions are used as intermediate variables to perform double 0 or double 1 judgment, and when it is confirmed that there is no double 0 or double 1 fault, the output function block finally outputs the switch instruction; If it is determined that there is a double 0 or double 1 fault phenomenon, the output function block outputs the normal value of the previous moment as the final switch instruction; The switch instructions are all connected to the terminal module, and the terminal module sends the control signal to the corresponding main contact of the bistable magnetic latching relay through hard wiring. The S end and R end of the bistable magnetic latching relay correspond to the opening instruction and closing instruction of the valve respectively. When either end receives the instruction, the bistable magnetic latching relay switches the state accordingly to realize the opening and closing of the valve.

2. The control method for avoiding malfunction of equipment due to controller or card failure according to claim 1, characterized in that: The controller transmits the switch command signal to the DO module through the backplane and then transmits the control signal to the terminal module through the threshold cable.

3. The control method for avoiding malfunction of equipment due to controller or card failure according to claim 2, characterized in that: The DO module includes two DO channels.

4. The control method for avoiding malfunction of equipment due to controller or card failure according to claim 3, characterized in that: The switch command is connected to the terminal module through two DO channels respectively, the opening command is connected to the terminal channel through the first DO channel, and the closing command is connected to the terminal channel through the second DO channel.

5. The control method for avoiding malfunction of equipment due to controller or card failure according to claim 4, characterized in that: When the solid-state relay access signal of the first DO channel is 0, the solid-state relay of the second DO channel is activated and its auxiliary contact is closed; When the solid-state relay of the first DO channel is activated by the access signal being 1, its auxiliary contact is closed, and the solid-state relay of the second DO channel is in an inactive state.

6. The control method for avoiding malfunction of equipment due to controller or card failure according to claim 1, characterized in that: The off instruction and the on instruction obtained by self-negation thereof are a pair of mutually exclusive on and off instructions.

7. The control method for avoiding malfunction of equipment due to controller or card failure according to claim 1, characterized in that: After receiving an instruction, the bistable magnetic latching relay maintains the state until receiving an opposite instruction, without the need for continuous current maintenance.

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