Rod position control system based on single PLC and control method thereof

Abstract

The invention discloses a single PLC rod control system and a control method, relates to the field of nuclear power plant rod position control, and is used for solving the problems of large occupied space and high manufacturing cost of the existing PLC rod control system. The system comprises a human-computer interface, a PLC control unit and a rod position control case, and the human-computer interface can transmit a control signal to the PLC control unit and can also receive and display a feedback signal of the PLC control unit; the PLC control unit comprises a digital quantity input module, a digital quantity output module, a PLC module and a communication module, and a hardware part of the PLC control unit adopts a multi-slot rack; the rod control machine box comprises a lifting machine box body, a transferring machine box body and a maintaining machine box body, and lifting, transferring and maintaining actions are conducted after signals of the PLC control unit are received.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power plant rod position control, specifically relating to a rod position control system and control method based on a single PLC. Background Technology

[0002] The reactor is the core component of a nuclear power plant. The control and position monitoring system for the reactor control rods, hereinafter referred to as the rod control system, is a key instrument and control system for reactor power control. The control logic part of the rod control system in a certain nuclear power plant is mainly composed of PLCs. Currently, the rod control system of this nuclear power plant consists of three sets of PLCs: a logic cabinet PLC, a power supply cabinet PLC, and a processing cabinet PLC.

[0003] The logic cabinet PLC receives signals from the main control room, the host computer screen, and other systems, including rod selection, lifting, lowering, mode selection, and operation commands. After logical judgment, the logic cabinet periodically generates lifting and lowering commands, which are then sent to the power supply cabinet. The power supply cabinet PLC receives the lifting and lowering commands from the logic cabinet, generates timing excitations for three types of coils, and outputs them to the lifting chassis, the transfer chassis, and the holding chassis. The processing cabinet PLC receives the rod position measurement signals from the measurement cabinet, performs calculations, generates alarm signals based on judgments, and transmits these signals to the alarm system. In other nuclear power plants already built in my country, the rod control system also uses the same structure. If the rod control card test cabinet were designed with the above structure, it would result in high costs and large space requirements. Summary of the Invention

[0004] The purpose of this invention is to provide a rod position control system and control method based on a single PLC, which solves the problem that the existing nuclear power plant rod control system requires three PLCs, thereby reducing the space occupied by the rod control system and lowering the system cost.

[0005] The technical solution adopted by this invention to solve its technical problem is: a bar positioning control system based on a single PLC, wherein the system includes: a human-machine interface, a PLC control unit, and a bar positioning control chassis. The human-machine interface can transmit control signals to the PLC control unit, and can also receive feedback signals from the PLC control unit and display them. The PLC control unit includes: a digital input module, a digital output module, a PLC module, and a communication module, and its hardware adopts a multi-slot rack. The bar positioning control chassis includes: a lifting chassis, a passing chassis, and a holding chassis. After receiving the signal from the PLC control unit, it performs lifting, passing, and holding actions.

[0006] In the aforementioned rod positioning control system based on a single PLC, the feedback signals received by the human-machine interface from the PLC control unit include: equipment fault status and running step count.

[0007] The above-mentioned rod position control system based on a single PLC includes a multi-slot rack in which the power supply module, PLC module, communication module, and digital output module each occupy one slot, the digital input module occupies two slots, and a spare slot is reserved.

[0008] The above-mentioned bar positioning control system based on a single PLC, wherein the PLC module can generate large and small current output signals for the hoisting coil, the transmission coil and the holding coil by logically judging the output signal, and transmit the signals to the hoisting box, the transmission box and the holding box through the digital output module.

[0009] In the aforementioned bar positioning control system based on a single PLC, when an emergency failure occurs in the PLC bar positioning control system, the lifting coil and the transmission coil will be energized simultaneously, causing the lifting box and the transmission box to operate simultaneously to ensure that the control bar does not fall due to the failure.

[0010] A rod position control method based on a single PLC includes seven steps, performed in the order of step one to step seven. Step one involves analog signal processing, converting the rod speed into a period for rod speed control. Step two involves receiving and executing instructions, accepting external lift and drop instructions, and interlocking these instructions to prevent simultaneous lift and drop. Step three involves initializing PLC logic variables, initializing the variables in the PLC module upon initial power-on or reset. Step four involves PLC reset, clearing the counters and resetting the holding, transfer, and lift mechanisms. The fifth step is fault diagnosis, determining if the equipment has an emergency fault. When proceeding to step six, the diagnosis begins. Step six determines whether a boost command can be output. If yes, it jumps back to step one; otherwise, it proceeds to step seven. Step seven determines whether an insert command can be generated. If yes, it jumps to step two; otherwise, it returns to step one and repeats the cycle periodically. The two jump steps are designed to reduce the PLC logic operation time. Jump step one outputs the boost command and the signal to increment the cumulative step count by 1, and returns to step one for periodic repetition. Jump step two outputs the insert command and the signal to increment the cumulative step count by 1, and returns to step one for periodic repetition.

[0011] The above-mentioned rod position control method based on a single PLC includes the following variables in step three, PLC logic variable initialization: the start and end times of the current of the three coils (lift, transmit, and hold), the internal counter, the start and end flags of the coil current, and the lockout bits for lifting and lowering.

[0012] The above-mentioned rod position control method based on a single PLC involves the following step: when the PLC executes step six, it makes a judgment. If the conditions for forming a lift instruction are met, step seven and jump step two are not executed. Instead, jump step one is executed directly, and then the PLC returns to step one to continue executing logical operations in this order. In this case, the PLC execution order is: step one, step two, step three, step four, step five, step six, jump step one, step one.

[0013] In the above-mentioned rod position control method based on a single PLC, if the conditions for forming a boost instruction are not met when the PLC executes step six, then step seven is executed to make another judgment. If the conditions for forming an insert instruction are met, then step two is executed, and then the PLC returns to step one to continue executing the logic operation. In this case, the PLC execution sequence is step one, step two, step three, step four, step five, step six, step seven, jump step two, step one.

[0014] In the above-mentioned rod position control method based on a single PLC, when the PLC executes step seven for judgment, if the conditions for forming the insertion instruction are not met, it will return to step one to re-execute the logic operation. In this case, the PLC execution sequence is step one, step two, step three, step four, step five, step six, step seven, step one.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a rod position control system and control method based on a single PLC, which integrates the logic cabinet PLC function and the power supply cabinet PLC function into a single PLC rod control system. Compared with multiple PLC systems, the structure of a single PLC system is simpler, saving cabinet space and achieving cost savings. Attached Figure Description

[0016] Figure 1 The diagram shown is of a rod position control system based on a single PLC according to the present invention.

[0017] Figure 2 The diagram shows the PLC module configuration of a rod position control system based on a single PLC according to the present invention. Detailed Implementation

[0018] To address the issues of large space requirements and high cost in existing PLC rod control systems, this invention provides a rod positioning control system and method based on a single PLC. Multiple PLCs are configured such that the logic cabinet PLC receives rod selection, lifting, insertion, mode selection, and operation commands, as well as P4 NOT signals, from the main control room, the host computer screen, and other systems. The PLC module outputs lifting / insertion control commands. Simultaneously, the remaining power cabinet PLCs receive the lifting / insertion control signals output by the logic cabinet module. These power cabinet PLCs then process the logic signals and output control signals for the large and small currents of the lifting coil, transmission coil, and holding coil through digital output modules.

[0019] A single PLC receives rod selection, lifting, lowering, mode selection, run commands, and P4 NOT signals from the main control room, the host computer screen, and other systems. After logic processing, it outputs control signals for the large and small currents of the lifting coil, the transmission coil, and the holding coil through the PLC module. Compared to multiple PLC systems, a single PLC system only requires one PLC and one rack to complete all logic control, while a multi-PLC system requires at least two PLCs and two racks to complete the corresponding control.

[0020] like Figure 1 , Figure 2 As shown, a bar positioning control system based on a single PLC is presented. This system consists of a human-machine interface (HMI), a PLC control unit, and a bar positioning control chassis. The HMI can send control signals to the PLC control unit and also receive and display fault information and running step counts from the PLC control unit. The PLC control unit hardware uses a 7-slot rack: slot 0 is for the power module; slot 1 is for the PLC module: the PLC module, through logic judgment, outputs signals to generate large and small current output signals for the lifting coil, transmission coil, and holding coil, and transmits these signals to the lifting chassis, transmission chassis, and holding chassis via a digital output module; slot 2 is for the communication module: used for communication with the host computer; slots 3 and 4 are for digital input modules: used to receive control signals from the HMI; slot 5 is for digital output modules: used for large and small current command output; and slot 6 is a spare slot. The bar positioning control chassis includes a lifting chassis, a transmission chassis, and a holding chassis. After receiving signals from the PLC control unit, it performs lifting, transmission, and holding actions. When an emergency failure occurs in the PLC rod positioning control system, the lifting coil and the transmission coil will be energized simultaneously, causing the lifting box and the transmission box to operate at the same time to ensure that the control rod does not fall due to the failure.

[0021] A rod position control method based on a single PLC integrates the functions of a logic cabinet and a power supply cabinet. This control method includes 7 steps and 2 jump steps: Step 1: Analog signal processing; Step 2: Instruction reception and execution; Step 3: PLC logic variable initialization; Step 4: PLC reset; Step 5: Fault diagnosis; Step 6: Determine if a boost command can be output; if yes, jump to Step 1; otherwise, proceed to Step 7; Jump to Step 1: Output the boost command and the cumulative step count increment signal, and return to Step 1 for periodic looping; Step 7: Determine if an insert command can be formed; if yes, jump to Step 2; otherwise, return to Step 1 for periodic looping; Jump to Step 2: Output the insert command and the cumulative step count increment signal, and return to Step 1 for periodic looping.

[0022] The two jump steps are designed to reduce the PLC's logic operation time. When the PLC executes step six, it makes a judgment. If the conditions for forming a boost instruction are met, then step seven and jump step two are not executed. Instead, jump step one is executed directly, and then the PLC returns to step one to continue executing the logic operation in this order. In this case, the PLC execution order is step one, step two, step three, step four, step five, step six, jump step one, step one.

[0023] When the execution reaches step six, if the conditions for forming a boost instruction are not met, then step seven is executed to make another judgment. If the conditions for forming an insert instruction are met, then step two is executed, and then the execution returns to step one to continue the logical operation. In this case, the PLC execution order is step one, step two, step three, step four, step five, step six, step seven, jump to step two, step one.

[0024] When the PLC reaches step seven for judgment, if the conditions for forming the insertion instruction are not met, it will return to step one to re-execute the logic operation. In this case, the PLC execution order is step one, step two, step three, step four, step five, step six, step seven, step one.

[0025] The above 7 steps and 2 jump steps are as follows:

[0026] Step 1: Analog signal processing: Acquire the manual bar speed Gray code signal, convert the acquired Gray code into a decimal number, and convert the decimal bar speed into a period for bar speed control.

[0027] Step Two: Command Reception and Execution: Receive lift and insert commands from the HMI (Human Machine Interface) and interlock these commands to prevent simultaneous execution. If a lift command is received but this step is not completed, the insert command cannot be executed, even if an insert command is input at that time. The insert command is only executed after the lift step is completed. Lift and insert commands cannot occur simultaneously, and valid lift and insert commands are generated periodically.

[0028] Step 3: PLC logic variable initialization: When the PLC is powered on for the first time or reset, the variables in the logic are initialized, including the start and end times of the large and small currents of the three coils of lift, pass, and hold, as well as the internal counter, the start and end flags of the large and small currents of the three coils of lift, pass, and hold, and the lockout bits of lift and push.

[0029] Step 4: PLC Reset: When the PLC reset button is pressed, the internal counter will be reset, the timing timer will be raised and inserted, the start and end flags of the large and small currents of the three coils will be raised, transmitted and held, and the latch position will be raised and lowered.

[0030] Step 5: Fault diagnosis: Determine if the equipment has any urgent faults.

[0031] Step Six: Determine if an escalation command can be output: If the conditions of receiving an escalation command, having no emergency faults in the device, and having no insertion commands are met, an escalation command is generated, and the process jumps to Step One.

[0032] Step 7: Determine if an insert instruction can be formed: If the conditions of receiving an insert instruction, having no emergency faults in the device, and having no escalation instructions are met, an insert instruction will be formed, and the process will jump to Step 2.

[0033] Jump to step one: Output the boost command and the signal to increment the cumulative step count by 1, and return to step one to perform a periodic loop.

[0034] Jump to step two: Output the signal of inserting the command and incrementing the cumulative step count by 1, and return to step one to perform a periodic loop.

[0035] It should be noted that the combination of the technical features in the embodiments of the present invention is not limited to the combination methods described in the embodiments of the present invention or the combination methods described in the specific embodiments. All technical features described in the present invention can be freely combined or combined in any way, unless there is a contradiction between them.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications or equivalent substitutions made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rod positioning control system based on a single PLC, characterized in that, The system includes: a human-machine interface (HMI), a PLC control unit, and a rod position control chassis. The HMI can transmit control signals to the PLC control unit and also receive and display feedback signals from the PLC control unit. The PLC control unit includes: a digital input module, a digital output module, a PLC module, and a communication module, and its hardware uses a multi-slot rack. The rod position control chassis includes: a lifting chassis, a passing chassis, and a holding chassis. After receiving signals from the PLC control unit, it performs lifting, passing, and holding actions.

2. The rod position control system based on a single PLC according to claim 1, characterized in that, The feedback signals received by the human-machine interface from the PLC control unit include: equipment fault status and running step count.

3. The rod position control system based on a single PLC according to claim 1, characterized in that, In a multi-slot rack: the power supply module, PLC module, communication module, and digital output module each occupy one slot, the digital input module occupies two slots, and a spare slot is reserved.

4. The rod position control system based on a single PLC according to claim 1, characterized in that, The PLC module outputs signals through logical judgment, which can stimulate the generation of large and small current output signals for the lifting coil, the transmission coil, and the holding coil, and transmit the signals to the lifting housing, the transmission housing, and the holding housing through the digital output module.

5. A rod position control system based on a single PLC according to claim 4, characterized in that, When an emergency failure occurs in the PLC rod positioning control system, the lifting coil and the transmission coil will be energized simultaneously, causing the lifting box and the transmission box to operate at the same time to ensure that the control rod does not fall due to the failure.

6. A rod position control method based on a single PLC, characterized in that, This control method comprises seven steps, with bar position control performed in the order of steps one through seven. Step one involves analog signal processing, converting the bar speed into a period for bar speed control. Step two involves receiving and executing commands, accepting external lift and drop commands, and interlocking these commands to prevent simultaneous lift and drop. Step three involves initializing PLC logic variables, initializing the variables in the PLC module upon initial power-on or reset. Step four involves PLC reset, clearing the counter and resetting the holding, transfer, and lift mechanisms. Step five involves fault diagnosis, determining the fault location... Check for emergency faults; when proceeding to step six, a judgment is made. Step six determines whether a boost command can be output. If yes, it jumps to step one; otherwise, it proceeds to step seven. Step seven determines whether an insert command can be generated. If yes, it jumps to step two; otherwise, it returns to step one and repeats the cycle. The two jump steps are designed to reduce the PLC logic operation time. Jump step one outputs the boost command and the signal to increment the cumulative step count by 1 and returns to step one for a cycle. Jump step two outputs the insert command and the signal to increment the cumulative step count by 1 and returns to step one for a cycle.

7. The rod position control method based on a single PLC according to claim 6, characterized in that, The variables in the PLC logic variable initialization step three include: the start and end times of the currents of the three coils (lift, pass, and hold), the internal counter, the start and end flags of the coil currents, and the latch bits for lift and push.

8. A rod position control method based on a single PLC according to claim 6, characterized in that, When the PLC executes step six, it makes a judgment. If the conditions for forming a boost instruction are met, then step seven and jump step two are not executed. Instead, jump step one is executed directly, and then the PLC returns to step one to continue executing the logical operation in this order. In this case, the PLC execution order is step one, step two, step three, step four, step five, step six, jump step one, step one.

9. A rod position control method based on a single PLC according to claim 6, characterized in that, When the PLC executes step six, if the conditions for forming a boost instruction are not met, then step seven is executed to make another judgment. If the conditions for forming an insert instruction are met, then step two is executed, and then the PLC returns to step one to continue executing the logic operation. In this case, the PLC execution order is step one, step two, step three, step four, step five, step six, step seven, jump step two, step one.

10. A rod position control method based on a single PLC according to claim 6, characterized in that, When the PLC executes to step seven for judgment, if the conditions for forming the insertion instruction are not met, it will return to step one to re-execute the logic operation. In this case, the PLC execution order is step one, step two, step three, step four, step five, step six, step seven, step one.

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