An automatic compensation and correction device for valve position and over-torque protection control device of an electric control valve

Abstract

The present invention relates to an automatic compensation and correction device for the valve position of an electric control valve and an over-torque protection control device. The device includes a DCS valve position main control system, a DCS valve position compensation and correction control system, and an over-torque protection control system. The DCS valve position main control system is connected to the electric control valve through a cable for feedback signal connection. The DCS valve position main control system is connected to a command signal relay switching device through a cable for command signal connection. Inside the relay switching device, the command signal is continuously output through a normally closed contact and connected to the input end of a command signal distributor through a cable. The first output end of the command signal distributor is connected to the electric control valve through a cable for command connection. The input end of the DCS valve position compensation and correction control system is connected to the second output end of the command signal distributor through a cable. This solution enables the automatically controlled valve opening to be infinitely close to the command signal, with precise and reliable valve position control, fully ensuring stable and smooth production.

Description

Technical Field

[0001] The present invention relates to a control device, and more particularly to an automatic valve position compensation correction and over-torque protection control device for an electric control valve, belonging to the technical field of electric control valve control. Background Art

[0002] At present, the medium control of the production process pipelines of thermal power generation, waste heat power generation in Meigang Thermal Power Plant and blast furnace fans mainly relies on electric control valve equipment. Through the DCS automatic control system, remote closed-loop control of the on-site valve opening is realized, and the pressure, flow rate and flow direction of the medium in the production process pipeline are controlled. However, the problem is that whether it is open-loop or closed-loop control, due to a certain error existing in the built-in feedback mechanism of the actuator after long-term operation, after the control system issues an opening command, there is a certain deviation between the actual valve position and the command. This technology mainly aims at the deviation between the actual valve position on-site of the control valve and the control command after the control system completes the closed-loop control, and eliminates the deviation between the actual valve position and the command through an automatic valve position compensation correction control method to ensure the improvement of control accuracy. Especially after the electric control valve has been out of service for a long time, it is very easy to have a large pressure difference between the medium before and after the valve. When the electric remote control operates the valve, the existing torque of the actuator cannot normally start the valve, and it is necessary to manually start it on-site through a crank. In a high-temperature and high-pressure control process environment, it is very easy to cause personal injury and great danger.

[0003] Through a novelty search in VIP, at present, most of the domestic electric control valves for production process control and regulation are open-loop or closed-loop feedback control. The on-site valve opening reflected by the control result is also converted into a standard signal through the feedback mechanism and sent to the upper computer such as DCS or PLC for closed-loop control. After retrieval, there is no relevant technical source for secondary accurate detection of the valve opening or further adjustment to make the valve opening accurately consistent with the command. After further retrieval, there is no good solution for the domestic problem that the valve cannot be normally opened due to a large pressure difference between the front and back of the valve before the control valve starts.

[0004] Therefore, aiming at the problems existing in the actual operation process of the above-mentioned electric control valve, it is very necessary to invent a control device and a control method for secondary detection and correction of the actual opening of the electric control valve, and at the same time design a method to solve the problem that the electric control valve is difficult to open and the torque of the actuator is insufficient, resulting in the burning of the servo motor. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides an automatic valve position compensation and correction and over-torque protection control device for an electric control valve. This technical solution designs a control device for actual valve position compensation and correction aiming at the actual valve position error existing in the electric control valve with automatic closed-loop control, and finally realizes that the opening of the automatically controlled valve is infinitely close to the command signal, the valve position control is accurate and reliable, and fully ensures the stable and smooth production. At the same time, by detecting the torque online, it controls the pressure difference balance before and after the valve or cuts off the power supply of the motor drive to protect the servo motor of the actuator from the safety hazard of over-torque coil burnout.

[0006] To achieve the above object, the technical solution of the present invention is as follows: an automatic valve position compensation and correction and over-torque protection control device for an electric control valve, the device includes a DCS valve position main control system, a DCS valve position compensation and correction control system, and an over-torque protection control system. The DCS valve position main control system is connected with the electric control valve through a cable for feedback signal connection, and the DCS valve position main control system is connected with the command signal relay switching device through a cable for command signal connection. Inside the relay switching device, the command signal is continuously output through a normally closed contact and connected to the input end of the command signal distributor through a cable. The first output end of the command signal distributor is connected with the electric control valve through a cable for command connection; the input end of the DCS valve position compensation and correction control system is connected with the second output end of the command signal distributor through a cable, its feedback input end is directly connected with the output end of the laser rangefinder through a cable, and its output end is connected with the command signal relay switching device through a cable. Inside the relay switching device, it is connected with the input end of the command signal distributor through a normally open contact. The DCS valve position main control system includes the feedback signal of the received electric control valve. The command signal output after comparison inside the DCS passes through the normally closed point of the relay switching device and then is output to the signal distributor, and then is output by the signal distributor to the control loop of the electric control valve to control the valve action; the DCS valve position compensation and correction control system includes the feedback signal of the received laser rangefinder; the main control command feedback signal from the received command signal distributor; the two feedback signals are compared inside the DCS to obtain a deviation and then output a valve position correction signal, which passes through the normally open point of the relay switching device and then is output to the signal distributor, and then the correction signal is output by the signal distributor to the control loop of the electric control valve to control the valve to be accurately adjusted.

[0007] As an improvement of the present invention, the over-torque protection control system includes a torque control device, a torque detector, a differential pressure balance electric control valve, a valve rear pressure measuring point, a valve front pressure measuring point and a driving power supply. An actual valve scale indicating rod is installed at the valve core action link of the on-site electric control valve, and a laser rangefinder is fixedly installed below it. A torque detector is installed at the action stroke mechanism at the other end of the electric control valve. The output end of the torque detector is connected to the input end of the torque control device through a cable. The first output end of the torque control device is connected to the coil of the differential pressure balance electric control valve through a cable, and the second output end is connected to the driving power supply of the electric control valve through a cable. The driving power supply and the actuator motor are connected through a cable for switching.

[0008] As an improvement of the present invention, a valve front pressure measuring point is installed on the pipeline in front of the electric control valve body, a valve rear pressure measuring point is installed on the pipeline behind it, a differential pressure balance pipeline is installed between the valve front pipeline and the valve rear pipeline, and a differential pressure balance electric control valve is installed in the middle of the differential pressure balance pipeline. Before the valve is normally opened online, due to the direction of medium flow, theoretically the valve front pressure is greater than the valve rear pressure, that is, P1 > P2. The torque to open the valve mainly overcomes the differential pressure force ΔP = P1 - P2 between the front and rear of the valve. The torque detector online detects the driving torque value of the electric control valve motor. The torque control device receives the measured value of the torque sensor and compares it with the first-order set value SP1. When the measured value is greater than the SP1 set value, it outputs a control signal to drive the differential pressure balance electric control valve to open, so that the valve front pressure P1 and the valve rear pressure P2 tend to be balanced, and the differential pressure between the front and rear of the valve is made equal as much as possible, and the valve can be normally opened.

[0009] In this technical solution, the control method is as follows:

[0010] 1) After the DCS valve position main control system receives the feedback signal input from the on-site electric control valve, it outputs a control instruction through comparison and sends it through the normally closed contact of the command signal relay switching device, enters the command signal distributor, and then the command signal distributor outputs a corresponding control signal to drive the electric control valve to act to complete the closed-loop control of the valve.

[0011] 2) The DCS compensation and correction control system performs a secondary comparison between the main control command current signal and the actual valve position current signal collected by the on-site laser rangefinder, and outputs a correction current signal to the relay switching device. At this time, the DCS compensation and correction control system immediately sends a switching signal to the relay switching device to make the coil energized and act. The normally closed contact inside the relay switching device becomes normally open, and the normally open contact closes. That is, the compensation and correction current signal enters the command signal distributor through the contact of the relay switching device and outputs a control signal to the electric control valve for precise control of valve position compensation and correction.

[0012] 3) Before the electric control valve is started, since the pressure before the valve is always greater than the pressure after the valve, that is, P1>P2, a pressure difference is generated before and after the valve, causing the valve to fail to start normally. At this time, the torque control device receives the torque value measured on-site by the torque sensor as a feedback signal, and compares it with the set value SP1. If the torque measurement value is greater than the first-order set value SP1, the pressure difference balancing electric control valve is driven to open, so that the pressure difference before and after the electric control valve tends to be balanced, reducing the starting pressure and facilitating the normal opening of the valve; if the torque measurement value continues to be greater than the second-order set value SP2, the actuator drive power supply is immediately controlled to be cut off to protect the servo motor coil of the electric control valve from burning due to excessive torque action.

[0013] Compared with the prior art, the present invention has the following advantages: 1) The technical solution accurately measures the actual feedback scale through laser secondary detection of the actual valve position and converts it into a control signal through the control system to compensate and correct the control output; 2) The solution designs a control method for automatic correction, compensation and correction of valve position control deviation, and further realizes automatic switching of the main control signal and the correction signal through the relay switching device, so as to realize accurate control of the controlled valve; 3) An electric regulating valve torque control device is designed, which further links the driving power supply through online measurement of the torque and control of the pressure difference balance before and after the valve, and fully protects the safety of the electric valve actuator motor. The torque control device measures the motor torque value online, and the first step is to link the pressure difference balance valve to reduce the valve starting pressure difference, so as to facilitate the valve opening; the second step is to link the actuator motor drive power supply circuit, and immediately cut off the actuator motor drive power supply when the dangerous set value SP2 is exceeded. Because if the motor continues to act with excessive torque, the valve does not respond, which will cause the valve stem to break mechanically and the medium to leak; the motor coil is overloaded and burned, causing a fire accident. The power switch short-circuit trips, causing large-scale power outages, causing the accident to expand. This solution solves the above problems by driving the power switch circuit through over-torque linkage. It can avoid the valve stem fracture and medium leakage caused by the motor's continuous over-torque action. It can avoid the motor coil overload and burning, which may cause fire accidents. It can avoid the power switch short circuit tripping, causing large-scale power tripping of the control system, and causing the accident to expand. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the overall structure of the valve position automatic compensation correction and over-torque protection control device;

[0015] Figure 2 Principle block diagram of valve position automatic compensation correction control and torque protection control.

[0016] In the figure: 1. Driving power supply; 2. DCS valve position main control system; 3. Instruction signal relay switching device; 4. Instruction signal distributor; 5. Actuator motor; 6. Actual valve scale indication; 7. Electric control valve; 8. Torque detector; 9. Torque control device; 10. Laser rangefinder; 11. Valve outlet pressure measuring point; 12. Differential pressure balance electric control valve; 13. Valve inlet pressure measuring point; 14. DCS valve position compensation and correction control system. Specific implementation mode

[0017] In order to deepen the understanding of the present invention, the following will make a detailed description of this embodiment in conjunction with the attached drawings.

[0018] Embodiment 1: Refer to Figure 1 、 Figure 2, an automatic compensation and correction device for the valve position of an electric control valve and an over-torque protection control device. The device includes a DCS valve position master control system 2, a DCS valve position compensation and correction control system 14, and an over-torque protection control system. The DCS valve position master control system 2 is connected to the electric control valve 7 through a cable for feedback signal connection. The DCS valve position master control system 2 is connected to the command signal relay switching device 3 through a cable for command signal connection. Inside the relay switching device 3, the command signal is continuously output through a normally closed contact and connected to the input end of the command signal distributor 4 through a cable. The first output end of the command signal distributor 4 is connected to the electric control valve 7 through a cable for command connection; the input end of the DCS valve position compensation and correction control system 14 is connected to the second output end of the command signal distributor 4 through a cable, its feedback input end is directly connected to the output end of the laser rangefinder 10 through a cable, and its output end is connected to the command signal relay switching device 3 through a cable. Inside the relay switching device 3, it is connected to the input end of the command signal distributor 4 through a normally open contact. The DCS valve position master control system contains the feedback signal of the electric control valve received. The command signal output after comparison inside the DCS passes through the normally closed point of the relay switching device and then is output to the signal distributor, and then is output by the signal distributor to the control loop of the electric control valve to control the valve action; the DCS valve position compensation and correction control system contains the feedback signal of the laser rangefinder received; the main control command feedback signal from the received command signal distributor; the two feedback signals are compared inside the DCS to obtain a deviation and then output a valve position correction signal, which passes through the normally open point of the relay switching device and then is output to the signal distributor, and then the correction signal is output by the signal distributor to the control loop of the electric control valve to control the precise adjustment of the valve. The over-torque protection control system contains a torque control device 9, a torque detector 8, a differential pressure balance electric control valve 12, a valve outlet pressure measuring point 11, a valve inlet pressure measuring point 13, and a drive power supply 1. A valve actual scale indicating rod 6 is installed at the link of the valve core movement of the on-site electric control valve 7, and a laser rangefinder 10 is fixedly installed below it. A torque detector 8 is installed at the other end movement stroke mechanism of the electric control valve 7. The output end of the torque detector 8 is connected to the input end of the torque control device 9 through a cable. The first output end of the torque control device 9 is connected to the coil of the differential pressure balance electric control valve 12 through a cable, and the second output end is connected to the drive power supply 1 of the electric control valve 7 through a cable. Among them, the drive power supply 1 is connected to the actuator motor 5 through a cable for switching connection. A valve inlet pressure measuring point 13 is installed on the pipeline in front of the valve body of the electric control valve 7, a valve outlet pressure measuring point 11 is installed on the pipeline behind it, a differential pressure balance pipeline is installed between the valve inlet pipeline and the valve outlet pipeline, and a differential pressure balance electric control valve 12 is installed in the middle of the differential pressure balance pipeline. Before the valve is normally opened online, due to the direction of medium flow, theoretically the valve inlet pressure is greater than the valve outlet pressure, that is, P1 > P2. The torque for opening the valve mainly overcomes the differential pressure force ΔP = P1 - P2 between the front and back of the valve.The torque detector detects the driving torque value of the motor of the electric control valve online. The torque control device receives the measured value of the torque sensor and compares it with the first-order set value SP1. When the measured value is greater than the set value of SP1, it outputs a control signal to drive the differential pressure balance electric control valve to open, so that the pressure P1 before the valve and the pressure P2 after the valve tend to be balanced, and the pressure difference before and after the valve is made equal as much as possible, and the valve can be opened normally.

[0019] Working process: as above Figure 1 As shown in the figure: after the DCS valve position master control system 2 receives the feedback signal input from the on-site electric control valve 7, it outputs a control instruction through comparison and issues it through the normally closed contact of the command signal relay switching device 3, enters the command signal distributor 4, and then the command signal distributor 4 outputs a corresponding control signal to drive the electric control valve 7 to act to achieve the closed-loop control of the valve. Among them, the normally closed contact of the command signal relay switching device 3 controls the on-off of the main control command signal, and the normally open contact controls the on-off of the compensation correction signal. At the same time, the laser rangefinder 10 is installed below the actual scale indicating rod 6 of the on-site electric control valve 7. The laser rangefinder 10 sends the actual position of the valve movement to the DCS valve position compensation correction control system 14 through the ranging signal for feedback and calculation and converts it into a standard valve position current signal. At this time, the compensation correction control system 14 simultaneously receives the valve position main control command current signal sent by the main control system. The compensation correction control system 14 compares the main control command current signal with the on-site actual valve position current signal, outputs a correction current signal to the relay switching device. At this time, the compensation correction control system immediately sends a switch signal to the relay switching device coil to energize and act. The normally closed contact inside the relay switching device becomes normally open, and the normally open contact closes. That is, the correction current signal enters the command signal distributor through the contact of the relay switching device and outputs a control signal to the electric control valve for precise control of valve position compensation correction. A pressure measuring point 13 is set in front of the electric control valve, a pressure measuring point 11 is set behind the valve, a differential pressure balance electric control valve 12 is installed in front of and behind the electric control valve, the torque sensor 8 measures the driving torque value of the motor of the electric control valve online, and the torque control device 9 receives the measured value of the torque sensor 8 and compares it with the set value and outputs a control signal to drive the differential pressure balance electric control valve 12 to open, so that the differential pressure P1 and P2 before and after the electric control valve tend to be balanced, which is convenient for the valve to open normally; if the valve continues to maintain over-torque and cannot start the valve, the torque control device 9 directly outputs a contact signal to cut off the driving power supply 1 of the actuator motor 5. Prevent the accident that the electric actuator continues to act with over-torque and burns out the motor coil.

[0020] Such as Figure 2As shown in the principle block diagram of valve position automatic compensation correction control and torque protection control: The normal control of the electric control valve is that the DCS valve position main control system receives the valve position feedback signal, issues a control command to the signal switching device, and then outputs it to the electric control valve through the signal distributor to achieve the closed-loop control of the valve opening. The DCS valve position compensation correction control system receives the actual scale indication feedback signal of the valve position from the on-site laser rangefinder, and compares it with a main control command signal from the signal distributor in real time. Once there is a deviation, it immediately issues a switch command to control the signal switching device to act, that is, the main control command signal line is cut off, and the compensation correction command signal line is opened for control. Then, it is calculated and converted into a corrected current signal and output to the signal switching device, and then output to the electric control valve through the signal distributor for valve position compensation correction control until the on-site actual valve position indication is closest to and matches the control command signal to meet the production process requirements. When the electric control valve starts, since the pressure before the valve is always greater than the pressure after the valve, that is, P1 > P2, a pressure difference is generated before and after the valve, resulting in the valve being unable to start normally. At this time, the torque control device receives the torque value measured by the torque sensor on-site as the feedback signal, and compares it with the set value SP1 at the same time. If the torque measurement value is greater than the first-order set value SP1, it drives the differential pressure balance electric control valve to open, making the differential pressure before and after the electric control valve tend to balance and reducing the starting pressure; if the torque measurement value continues to be greater than the second-order set value SP2, it immediately controls to cut off the actuator drive power supply to protect the servo motor coil of the electric control valve from over-torque action and burnout.

[0021] If abnormal faults such as valve jamming occur and the normal torque of the motor cannot overcome other resistances to open the valve, that is, the torque measurement value is greater than the second-order SP2 set value, the torque control device immediately controls to cut off the actuator drive power supply to protect the servo motor coil of the electric control valve from over-torque action and burnout.

[0022] After the DCS valve position main control system receives the feedback signal input from the on-site electric control valve, it issues a control command through comparison and outputs it through the normally closed contact of the command signal relay switching device, enters the command signal distributor, and then the command signal distributor outputs the corresponding control signal to drive the electric control valve to act to achieve the closed-loop control of the valve.

[0023] The DCS valve position compensation and correction control system receives the ranging signal feedback from the laser rangefinder and calculates and converts it into a standard valve position current signal. At this time, the DCS compensation and correction control system also receives the valve position master control command current signal issued by the main control system. The DCS compensation and correction control system compares the master control command current signal with the actual valve position current signal on site, and outputs the correction current signal to the relay switching device. At this time, the DCS compensation and correction control system immediately sends a switch signal to the relay switching device coil to be energized, and the normally closed contacts inside the relay switching device become normally open, and the normally open contacts are closed, that is, the compensation correction current signal enters the command signal distributor through the contacts of the relay switching device and outputs the control signal to the electric control valve for precise control of the valve position compensation correction. Before the electric control valve is started, the pressure before the valve is always greater than the pressure after the valve, that is, P1>P2, and a pressure difference is generated before and after the valve, causing the valve to fail to start normally. At this time, the torque control device receives the torque value measured on-site by the torque sensor as a feedback signal, and compares it with the set value SP1. If the torque measurement value is greater than the first-order set value SP1, the pressure difference balancing electric control valve is driven to open, so that the pressure difference before and after the electric control valve tends to balance and the starting pressure is reduced; if the torque measurement value continues to be greater than the second-order set value SP2, the actuator drive power supply is immediately controlled to be cut off to protect the servo motor coil of the electric control valve from burning due to excessive torque action.

[0024] It can be seen that the scheme technology has designed a control method for automatic correction, compensation and modification of valve position control deviation, realizing precise control of the controlled valve, further improving the accuracy of valve position control, and fully ensuring stable and smooth production. At the same time, an electric regulating valve torque control device is designed, which facilitates the normal opening of the valve by measuring the torque online and controlling the pressure difference balance before and after the valve, and further links the drive power supply to fully protect the safety of the electric valve actuator motor.

[0025] It should be noted that the above embodiments are not intended to limit the protection scope of the present invention, and equivalent changes or substitutions made on the basis of the above technical solutions all fall within the protection scope of the claims of the present invention.

Claims

1. An automatic compensation and correction device for the valve position of an electric control valve and an over-torque protection control device, characterized in that, The device includes a DCS valve position main control system, a DCS valve position compensation and correction control system, and an over-torque protection control system. The DCS valve position main control system is connected to the electric control valve through a cable for feedback signal connection. The DCS valve position main control system is connected to the command signal relay switching device through a cable for command signal connection. Inside the relay switching device, the command signal is continuously output through a normally closed contact and connected to the input end of the command signal distributor through a cable. The first output end of the command signal distributor is connected to the electric control valve through a cable for command connection; the input end of the DCS valve position compensation and correction control system is connected to the second output end of the command signal distributor through a cable. Its feedback input end is directly connected to the output end of the laser rangefinder through a cable. Its output end is connected to the command signal relay switching device through a cable. Inside the relay switching device, it is connected to the input end of the command signal distributor through a normally open contact.

2. The electric control valve position automatic compensation correction and over-torque protection control device according to claim 1, characterized in that, The over-torque protection control system includes a torque control device, a torque detector, a differential pressure balance electric control valve, a valve outlet pressure measuring point, a valve inlet pressure measuring point, and a drive power supply. A valve actual scale indicating rod is installed at the action link of the electric control valve spool. A laser rangefinder is fixedly installed below it. A torque detector is installed at the action stroke mechanism at the other end of the electric control valve. The output end of the torque detector is connected to the input end of the torque control device through a cable. The first output end of the torque control device is connected to the coil of the differential pressure balance electric control valve through a cable. The second output end is connected to the drive power supply of the electric control valve through a cable. Among them, the drive power supply is connected to the actuator motor through a cable for switch connection.

3. The automatic compensation correction and over-torque protection control device for the valve position of the electric control valve according to claim 1, characterized in that, A valve inlet pressure measuring point is installed on the front pipeline of the electric control valve body, a valve outlet pressure measuring point is installed on the rear pipeline, a differential pressure balance pipeline is installed between the valve inlet pipeline and the valve outlet pipeline, and a differential pressure balance electric control valve is installed in the middle of the differential pressure balance pipeline.

4. The automatic compensation and correction device for the valve position of the electric control valve and the over-torque protection control device according to any one of claims 1-3, characterized in that, The control method is as follows: 1) After the DCS valve position main control system receives the feedback signal input from the on-site electric control valve, it outputs a control command through comparison and sends it through the normally closed contact of the command signal relay switching device, enters the command signal distributor, and then the command signal distributor outputs a corresponding control signal to drive the electric control valve to act to complete the closed-loop control of the valve. 2) The DCS compensation and correction control system performs a secondary comparison between the main control command current signal and the actual valve position current signal collected by the on-site laser rangefinder, and outputs a correction current signal to the relay switching device. At this time, the DCS compensation and correction control system immediately sends a switch signal to the relay switching device, and the coil is energized to act. The normally closed contact inside the relay switching device becomes normally open, and the normally open contact closes. That is, the compensation and correction current signal enters the command signal distributor through the contact of the relay switching device and outputs a control signal to the electric control valve for precise control of valve position compensation and correction. 3) Before the electric control valve starts, since the pressure in front of the valve is always greater than the pressure behind the valve, that is, P1 > P2, a pressure difference is generated before and after the valve, resulting in the valve being unable to start normally. At this time, the torque control device receives the torque value measured by the torque sensor on site as a feedback signal and compares it with the set value SP1 at the same time. If the measured torque value is greater than the first-order set value SP1, the differential pressure balance electric control valve is driven to actuate and open, so that the differential pressure before and after the electric control valve tends to be balanced, reducing the starting pressure and facilitating the normal opening of the valve; if the measured torque value continues to be greater than the second-order set value SP2, the driving power supply of the actuator is immediately controlled to cut off to protect the servo motor coil of the electric control valve from being damaged due to over-torque operation.

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