Turbine redundancy electro-hydraulic servo control method

Abstract

The invention relates to a redundant electro-hydraulic servo control method for a steam turbine, which takes a PLC (Programmable Logic Controller) as a core control unit, is equipped with a two-way oil supply cut-off valve and a cut-off hydraulic manifold block, cuts off an oil supply way of a faulty electro-hydraulic converter as required, and has the functions of alarming, locking and the like. And the fault converter with high output oil pressure is cut off in time, and the voting mechanism of the current redundant electro-hydraulic converter is perfected, so that the reliability of redundant electro-hydraulic servo control is improved.

Description

Technical Field

[0001] This invention relates to a control method, specifically a redundant electro-hydraulic servo control method for steam turbines, belonging to the field of steam turbine electro-hydraulic servo drive and automatic control technology. Background Technology

[0002] Steam turbine units and blower units are power units in the steel, petrochemical, and power industries. Among them, the electro-hydraulic servo system is the core component for the entire unit's regulation and control. This system is the interface for converting electronic signals into mechanical hydraulic signals. It has a complex structure, high precision, and stringent requirements for oil quality. Its equipment status and performance are critical aspects of the power unit, directly affecting the stability and safety of the production process. Although the electro-hydraulic servo drive section is important, its complex structure still makes it a single point of failure in the unit's control system.

[0003] In recent years, to improve the reliability of power units, some units have adopted redundant electro-hydraulic converter structures. Most redundant electro-hydraulic converters employ a high-selection outlet control oil pressure structure, meaning that of the two electro-hydraulic converters, the one with the higher output oil pressure is active. The purpose of this is that if one electro-hydraulic converter loses power or malfunctions, its outlet control oil pressure decreases. At this time, the electro-hydraulic converter with the higher output oil pressure automatically takes over control according to the high-selection principle, achieving dual redundancy of the electro-hydraulic converters and ensuring that the control valve or other actuators do not lose their driving hydraulic pressure.

[0004] While this type of highly selective redundant electro-hydraulic converter achieves redundancy in most cases, its redundancy structure is not perfect. In certain situations, such as when a converter's slide valve becomes stuck in the increased oil supply position, even though the converter is faulty and should not be driving the control valve, its output oil pressure will continue to increase because it is stuck in the increased oil supply position. This results in its outlet oil pressure being higher than that of another normal converter. Because it is a high-pressure selective device (determined by the structural characteristics of this type of redundant electro-hydraulic converter), the output oil pressure of the faulty converter becomes effective, causing it to continue operating or take over the operation of the normal converter, thus driving the turbine control valve to the wrong position. This is a serious potential fault and a system defect that cannot be solved by simply installing redundant converters. Therefore, a new solution is urgently needed to address this technical problem. Summary of the Invention

[0005] This invention addresses the technical problems existing in the prior art by providing a redundant electro-hydraulic servo control method for steam turbines. This technical solution can monitor and judge the operating status of redundant electro-hydraulic converters and promptly cut off faulty converters with high output oil pressure, thereby improving the voting mechanism of current redundant electro-hydraulic converters and enhancing the reliability of redundant electro-hydraulic servo control.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: a redundant electro-hydraulic servo control method for a steam turbine, the method comprising the following steps:

[0007] Step 1: Install a shut-off solenoid valve on each of the two electro-hydraulic converter's oil supply lines. During normal operation, the shut-off solenoid valve is fully open and de-energized. When the shut-off condition is met, it is energized and closes. Even if the control power is lost, the shut-off solenoid valve will not close due to power failure, ensuring unobstructed oil flow.

[0008] Step 2: Install five pressure sensors on the outlet hydraulic pipeline: supply oil pressure sensor A for electro-hydraulic converter A, control oil pressure sensor A for electro-hydraulic converter A, supply oil pressure sensor B for electro-hydraulic converter B, control oil pressure sensor B for electro-hydraulic converter B, and actual control oil pressure sensor.

[0009] Step 3: Add a PLC-based electronic device to comprehensively monitor and control the redundant electro-hydraulic conversion device.

[0010] Step 4: Acquire signals such as oil supply pressure, control oil pressure, valve position, and power status via hard-wiring and output signals such as shut-off valve command and system alarm; acquire information from the electro-hydraulic control controller, such as speed and valve command, via communication.

[0011] Step 5: Set up a screen to engage and disengage the electromagnetic shut-off valve in the oil inlet pipeline, and display the engagement and disengagement status of the electromagnetic valve.

[0012] Step Six: When the unit is running, the electronic monitoring device continuously monitors the oil pressure control commands output by the turbine control system and the oil pressure difference output by each electro-hydraulic converter. If the oil pressure difference of a certain electro-hydraulic converter is higher than the set difference and remains higher for a certain period of time, it can be determined that this electro-hydraulic converter is stuck, and the stuck position is at the high oil pressure output position. The monitoring system then outputs a cut-off command to cut off the cut-off valve on the oil supply pipeline of this faulty electro-hydraulic converter, thereby reducing the output oil pressure of this faulty electro-hydraulic converter, exiting the redundancy mechanism, and avoiding the output of incorrect valve commands to the turbine.

[0013] Step 7: The operator can select to enable or disable the shut-off valve function according to production needs. When enabled, it indicates that the PLC control system has the function of shutting off the solenoid valve. When the conditions in Step 6 are met, the corresponding solenoid valve will be shut off. When the function is disabled, even if all the above conditions are met, the PLC control system will no longer have the function of shutting off the solenoid valve.

[0014] Step 8: Set alarm information, including low oil pressure, speed probe failure, and execution command failure. Operators can use the alarm information to quickly find the cause of the failure and accurately locate the fault.

[0015] In step one, a shut-off solenoid valve A and a shut-off solenoid valve B are installed on the oil pressure pipelines of the two electro-hydraulic servo position valves. During normal operation, shut-off solenoid valves A and B are in a fully open state without power. When the shut-off condition is determined to be met, shut-off solenoid valve A or B is automatically energized to close the valve and cut off the oil supply to the electro-hydraulic servo position valve. Even if the control power is lost, the shut-off solenoid valve will not close due to power failure, ensuring that the oil supply circuit is unobstructed.

[0016] In step three, a PLC-based control system is added to comprehensively monitor and control the redundant electro-hydraulic conversion device. The control system consists of a CPU3152 PN / DP module, an analog input AI8×12bit module, an analog output AO8×12bit module, a digital input DI16×DC24V module, a digital output DO16×DC24V / 0.5A module, and a CP341 communication module. The CPU315-2PN / DP is the control core of the system. It uses an RJ45 Ethernet interface to communicate with the HMI KTP900PN. The PLC communicates with the WOODWARD 505 controller via Modbus through the DB15 pin interface of the CP341. The PLC acts as the master station, and the 505 controller acts as the slave station. The operator can operate and monitor the WSM redundant electro-hydraulic servo valve through the HMI.

[0017] Step 5: Set up the screen to engage and disengage the electromagnetic shut-off valve of the oil inlet pipeline, and display the engagement and disengagement status of the electromagnetic valve. When the system does not need to engage the electromagnetic valve, simply click the disengagement button on the screen. The screen also configures the corresponding measuring points to monitor the oil supply pressure A and B, control oil pressure A and B, actual control oil pressure, valve command A and B, valve position feedback A and B, etc. The screen displays the current status of each signal. When a signal fails, the corresponding line will turn red.

[0018] In step six, the logic judgment strategy for cutting off control valve A is as follows: if the following conditions are met simultaneously, it is determined that spool valve A is stuck in the oil supply position, and the PLC will cut off control valve A:

[0019] 1) The difference between the control oil pressure and the control oil pressure B is greater than 4% of the supply oil pressure A.

[0020] 2) The difference between control oil pressure A and control oil pressure B is greater than 4% of the supply oil pressure A.

[0021] 3) The difference between the gate position feedback A (LVDTA) and the gate instruction A (505) is greater than 4% of the gate instruction A.

[0022] 4) The difference between the gate position feedback B (LVDTB) and the gate instruction B (505) is greater than 4% of the gate instruction B.

[0023] 5) The valve position feedback signal A is normal.

[0024] 6) The regulating gate command A signal is normal.

[0025] 7) The valve position feedback signal B is normal.

[0026] 8) The B signal of the regulating gate is normal.

[0027] 9) The oil pressure supplying the electro-hydraulic servo position valve B is normal.

[0028] 10) The outlet oil pressure (control oil B pressure) of the electro-hydraulic servo position valve B is normal.

[0029] 11) The shut-off valve B command for electro-hydraulic servo position valve B is in the "not shut off" state.

[0030] Logical decision-making strategy for shutting off control valve B:

[0031] If the following conditions are met simultaneously, it will be determined that valve B is stuck in the oil supply position, and the PLC will cut off control of valve B.

[0032] 1) The difference between the control oil pressure and control oil pressure A is greater than 4% of the supply oil pressure B.

[0033] 2) The difference between control oil pressure B and control oil pressure A is greater than 4% of the supply oil pressure B.

[0034] 3) The difference between the gate position feedback A (LVDTA) and the gate instruction A (505) is greater than 4% of the gate instruction A.

[0035] 4) The difference between the gate position feedback B (LVDTB) and the gate instruction B (505) is greater than 4% of the gate instruction B.

[0036] 5) The valve position feedback signal A is normal.

[0037] 6) The regulating gate command A signal is normal.

[0038] 7) The valve position feedback signal B is normal.

[0039] 8) The B signal of the regulating gate is normal.

[0040] 9) The oil pressure supplying the electro-hydraulic servo position valve A is normal.

[0041] 10) The outlet oil pressure (control oil A pressure) of the electro-hydraulic servo position valve A is normal.

[0042] 11) The shut-off valve A command of electro-hydraulic servo position valve A is in the "not shut off" state.

[0043] All of the above deviation percentages have setting functions. Engineers can modify the deviation percentages under certain permissions, such as the deviation percentage between control oil A and B and supply oil A and B, and the deviation percentage between valve position feedback A and B and valve command A and B.

[0044] A redundant electro-hydraulic servo control system for a steam turbine, the control system comprising:

[0045] Oil supply line A, oil supply line B, shut-off valve A, shut-off valve B, oil supply pressure A, oil supply pressure B, control oil pressure A, control oil pressure B, control oil pressure, electro-hydraulic servo valve A, electro-hydraulic servo valve B, high-pressure selector, electronic monitoring device, valve command A, valve position feedback A, valve command B, and valve position feedback B. Oil supply line A supplies oil to electro-hydraulic servo valve A, and oil supply line B supplies oil to electro-hydraulic servo valve B. Shut-off valve A is located at the input end of electro-hydraulic servo valve A on oil supply line A, and shut-off valve B is located at the input end of electro-hydraulic servo valve B on oil supply line B. Both valves are used to shut off the oil supply to the electro-hydraulic servo valves in abnormal situations. Oil supply pressure sensors A and B are located between shut-off valves A and B and electro-hydraulic servo valves A and B on oil supply lines A and B, respectively, to measure the inlet oil pressure of electro-hydraulic servo valves A and B. Control oil pressure sensors A and B are located on the oil supply lines A and B, respectively, between the electro-hydraulic servo position valves A and B and the high-pressure selector, measuring the outlet oil pressure of the electro-hydraulic servo position valves A and B. The electro-hydraulic servo position valves A and B output two control oil lines, A and B, to the high-pressure selector. After high-pressure selection, the high-pressure selector outputs the final actual control oil pressure to the output control oil to control the power cylinder, driving the control valve. The control oil pressure sensor is located on the outlet side of the high-pressure selector and is used to measure the final actual control oil pressure of the redundant electro-hydraulic servo control system. Five pressure sensors (supply oil pressure A, supply oil pressure B, control oil pressure A, control oil pressure B, and control oil pressure) transmit 4-20mA measurement signals to the electronic monitoring device in the central control room via hard-wiring. The electronic monitoring device simultaneously collects control valve position feedback signals A and B from the field control valves and communication signals A and B from other controllers. After logical judgment, these signals output control commands, which control the opening and closing of shut-off valves A and B through a hard-wiring circuit.

[0046] Compared with existing technologies, this invention has the following advantages: 1) By designing a monitoring device, it compensates for the shortcomings of existing redundant electro-hydraulic converter fault judgment mechanisms, thereby taking corresponding measures in case of faults and avoiding the output of incorrect valve control commands to the turbine, thus improving the reliability of the unit. The monitoring device is an important component of the redundant electro-hydraulic servo system. When necessary, it can cut off the oil supply to the faulty electro-hydraulic converter. In this way, even if there are fault points that the redundant electro-hydraulic servo system cannot detect, the monitoring device can automatically cut off the faulty electro-hydraulic converter and switch to the normal electro-hydraulic converter through judgment.

[0047] 2) A method for determining valve jamming is provided. By monitoring parameters and performing logical judgment, the system automatically concludes that the electro-hydraulic converter valve is jammed. The corresponding setpoints for the logical judgment can be modified online according to the equipment status. When the system determines that the valve is jammed in the high oil pressure position, it sends a command to the corresponding shut-off valve, which is then energized to cut off the oil circuit.

[0048] 3) The shut-off valve is designed to open without power, eliminating the risk of the solenoid valve closing due to system power failure. Simultaneously, interlocking logic is incorporated into the control logic to prevent the simultaneous disconnection of oil supply to both electro-hydraulic converters if one circuit has already been shut off before the other is shut off.

[0049] 4) This monitoring system can comprehensively monitor redundant servo systems. Operators and maintenance personnel can receive alarm information immediately, quickly identify faults, locate the source of the fault, and take action.

[0050] 5) This monitoring device is a useful supplement to the application of redundant electro-hydraulic servo position valve technology in steam turbines. It can not only make up for the shortcomings of the existing redundant electro-hydraulic converter fault judgment mechanism, but also provide functions such as alarm and historical trend recording, ensuring the rigor and integrity of the redundant system. Attached Figure Description

[0051] Figure 1 : Schematic diagram of the servo system before improvement

[0052] Figure 2 Schematic diagram of the improved servo system

[0053] Figure 3 Schematic diagram of the improved monitoring system

[0054] Figure 4 : Schematic diagram of the improved shut-off valve control principle.

[0055] In the diagram: 1-Oil supply line A, 2-Oil supply line B, 3-Shut-off valve A, 4-Shut-off valve B, 5-Oil supply pressure A, 6-Oil supply pressure B, 7-Control oil pressure A, 8-Control oil pressure B, 9-Control oil pressure, 10-Electro-hydraulic servo valve A, 11-Electro-hydraulic servo valve B, 12-High-pressure oil selector, 13-Electronic monitoring device, 14-Regulator command A, 15-Regulator position feedback A, 16-Regulator command B, 17-Regulator position feedback B. Detailed Implementation

[0056] To enhance understanding of the present invention, the embodiments will be described in detail below with reference to the accompanying drawings.

[0057] Example 1: A redundant electro-hydraulic servo control system for a steam turbine, the control method of which is as follows: Taking the Meigang No. 3 AV90 turbine blower unit as an example, as follows... Figure 1 As shown, the original electro-hydraulic servo drive system consisted of an electronic control system signal (4-20mA), a Voith WayValve, and a feedback device (MLDT), as well as the unit's oil supply and discharge pipelines. The WayValve received the valve position command (4-20mA) from the control system, compared the command with the valve position feedback, and output control oil to control the power cylinder. Although the system control effect was good, all components were interconnected, and a failure in any component would cause the unit to shut down or experience significant load fluctuations.

[0058] The improved version uses a Voith WSM device, such as... Figure 2 As shown, the WSM is an integrated redundant device specially designed by Voith, including two completely independent electro-hydraulic servo valves (way valves, electro-hydraulic converters), hydraulic high-selectivity redundant voting components, and necessary instruments and manual switching devices, and is equipped with two sets of hydraulic actuator position feedback devices (MLDT). Dual valve position control commands are derived from the controller (505), and each electro-hydraulic servo valve receives an independent control command (4-20mA). The two outlet control oil circuits then undergo hydraulic redundancy voting to directly drive the oil cylinder.

[0059] While the improved high-selectivity redundant electro-hydraulic servo position valve achieves redundancy in the electro-hydraulic servo system, this redundancy structure is not perfect. To address the significant hazard of the electro-hydraulic servo position valve's slide valve jamming causing the turbine control valve to be driven to the wrong position, this system is further improved as follows:

[0060] Step 1, such as Figure 3 As shown, a shut-off solenoid valve A and a shut-off solenoid valve B are installed on the oil pressure pipelines of the two electro-hydraulic servo position valves. During normal operation, shut-off solenoid valves A and B are in a fully open, de-energized state. When the shut-off condition is met, shut-off solenoid valve A or B automatically energizes and closes the valve, cutting off the oil supply to the electro-hydraulic servo position valve. Even if the control power is lost, the shut-off solenoid valve will not close due to power failure, ensuring unobstructed oil supply.

[0061] Step Two, as follows Figure 3 As shown, five pressure sensors are installed on the hydraulic pipeline, namely, the oil supply pressure sensor A of electro-hydraulic servo valve A, the control oil pressure sensor A of electro-hydraulic servo valve A, the oil supply pressure sensor B of electro-hydraulic servo valve B, the control oil pressure sensor B of electro-hydraulic servo valve B, and the actual high-pressure control oil pressure sensor.

[0062] Step 3: Add a PLC-based control system to comprehensively monitor and control the redundant electro-hydraulic conversion device. In this embodiment, the control system uses a SIEMENS S7-300 series PLC. This control system consists of a CPU3152 PN / DP module, an analog input AI8×12bit module, an analog output AO8×12bit module, a digital input DI16×DC24V module, a digital output DO16×DC24V / 0.5A module, and a CP341 communication module. The CPU315-2PN / DP is the control core of the system, communicating with the KTP900PN HMI via an RJ45 Ethernet interface. The PLC communicates with the WOODWARD 505 controller via Modbus through the DB15 pin interface of the CP341, with the PLC acting as the master and the 505 controller as the slave. The operator can operate and monitor the WSM redundant electro-hydraulic servo valve through the HMI.

[0063] Step 4: Acquire analog input signals such as oil supply pressure, control oil pressure, and valve position, as well as switch output signals such as power status, through hard-wiring. Output switch output signals such as shut-off valve command and system alarm to other system valve position analog output signals. Acquire information from the electro-hydraulic control controller (505) such as speed and valve command signals through Modbus communication.

[0064] Step 5: Set up the screen to engage and disengage the electromagnetic shut-off valve in the oil inlet pipeline, and display the engagement and disengagement status of the solenoid valve. When the system does not need to engage the electromagnetic shut-off valve function, simply click the disengagement button on the screen. This screen also configures corresponding measuring points to monitor oil supply pressures A and B, control oil pressures A and B, actual control oil pressure, valve commands A and B, and valve position feedback A and B. This screen displays the current status of each signal; when a signal fails, the corresponding line will turn red.

[0065] Step Six: When the unit is running, the electronic monitoring device continuously monitors the status of various parameters of the control system. If a parameter of a certain electro-hydraulic servo valve is higher than the set difference for a certain period of time, it automatically determines that the electro-hydraulic servo valve is stuck, and the stuck position is at the high oil pressure output position. The monitoring system outputs a cut-off command, automatically cutting off the cut-off valve on the oil supply pipeline of the faulty electro-hydraulic servo valve, thereby reducing the output oil pressure of the faulty electro-hydraulic converter, exiting the redundancy mechanism, and avoiding the output of incorrect valve commands to the turbine. At the same time, interlocking logic is added to the control logic, prohibiting the cutting off of the other path when one path has been cut off, to prevent both sets of electro-hydraulic converters from cutting off oil at the same time.

[0066] Logical decision-making strategy for shutting off control valve A:

[0067] If the following conditions are met simultaneously, it will be determined that valve A is stuck in the oil supply position, and the PLC will cut off control valve A:

[0068] 1) The difference between the control oil pressure and the control oil pressure B is greater than 4% of the supply oil pressure A;

[0069] 2) The difference between control oil pressure A and control oil pressure B is greater than 4% of the supply oil pressure A;

[0070] 3) The difference between the gate position feedback A (LVDTA) and the gate instruction A (505) is greater than 4% of the gate instruction A;

[0071] 4) The difference between the gate position feedback B (LVDTB) and the gate instruction B (505) is greater than 4% of the gate instruction B;

[0072] 5) The valve position feedback A signal is normal;

[0073] 6) The gate control command A signal is normal;

[0074] 7) The valve position feedback signal B is normal;

[0075] 8) The B signal of the regulating gate is normal;

[0076] 9) The oil pressure supplying the electro-hydraulic servo position valve B is normal;

[0077] 10) The outlet oil pressure (control oil B pressure) of the electro-hydraulic servo position valve B is normal;

[0078] 11) The shut-off valve B command of the electro-hydraulic servo position valve B is in the "not shut off" state.

[0079] Logical decision-making strategy for shutting off control valve B:

[0080] If the following conditions are met simultaneously, it will be determined that valve B is stuck in the oil supply position, and the PLC will cut off the control valve B:

[0081] 1) The difference between the control oil pressure and the control oil pressure A is greater than 4% of the supply oil pressure B;

[0082] 2) The difference between control oil pressure B and control oil pressure A is greater than 4% of the supply oil pressure B;

[0083] 3) The difference between the gate position feedback A (LVDTA) and the gate instruction A (505) is greater than 4% of the gate instruction A;

[0084] 4) The difference between the gate position feedback B (LVDTB) and the gate instruction B (505) is greater than 4% of the gate instruction B;

[0085] 5) The valve position feedback A signal is normal;

[0086] 6) The gate control command A signal is normal;

[0087] 7) The valve position feedback signal B is normal;

[0088] 8) The B signal of the regulating gate is normal;

[0089] 9) The oil pressure supplying the electro-hydraulic servo position valve A is normal;

[0090] 10) The outlet oil pressure (control oil A pressure) of the electro-hydraulic servo position valve A is normal;

[0091] 11) The shut-off valve A command of electro-hydraulic servo position valve A is in the "not shut off" state.

[0092] All of the above deviation percentages have setting functions. Engineers can modify the deviation percentages under certain permissions, such as the deviation percentage between control oil A and B and supply oil A and B, and the deviation percentage between valve position feedback A and B and valve command A and B.

[0093] Step 7: Operators can select to enable or disable the shut-off valve function according to production needs. When enabled, it indicates that the PLC control system has the function of shutting off the solenoid valve. When the conditions in Step 6 are met, the corresponding solenoid valve will be shut off. When the function is disabled, even if all the above conditions are met, the PLC control system will no longer have the function of shutting off the solenoid valve. (When manually operating the redundant electro-hydraulic servo valve handle or replacing a faulty set of electro-hydraulic servo valves, the shut-off valve function must be disabled to prevent malfunction of the redundant electro-hydraulic converter due to misoperation.)

[0094] Step 8: Set alarm information, such as low oil pressure, speed probe failure, execution command failure, etc. Operators can monitor alarm information on this screen to quickly identify the cause of the fault and accurately locate the fault. After repairing the fault, click the alarm reset button to reset the alarm information. Under normal circumstances, the system's alarm indicator light is green. When an alarm occurs, the indicator light turns red, and the corresponding fault alarm blue bar also turns red and flashes. After clearing the fault, click the alarm reset button to reset the alarm information.

[0095] Example 2: A redundant electro-hydraulic servo control system for a steam turbine, the control system comprising...

[0096] Oil supply line A, oil supply line B, shut-off valve A, shut-off valve B, oil supply pressure A, oil supply pressure B, control oil pressure A, control oil pressure B, control oil pressure, electro-hydraulic servo valve A, electro-hydraulic servo valve B, high-pressure selector, electronic monitoring device, valve command A, valve position feedback A, valve command B and valve position feedback B, oil supply line A supplies oil to electro-hydraulic servo valve A, oil supply line B supplies oil to electro-hydraulic servo valve B, shut-off valve A is located on oil supply line A, and the input measurement of electro-hydraulic servo valve A is... At the front end, shut-off valve B is located at the input end of electro-hydraulic servo valve B on oil supply line B. Both valves are used to shut off the oil supply to the electro-hydraulic servo valve in abnormal situations. Oil supply pressure sensors A and B are located between shut-off valves A and B and electro-hydraulic servo valves A and B on oil supply lines A and B, respectively, to measure the inlet oil pressure of electro-hydraulic servo valves A and B. Control oil pressure sensors A and B are located between electro-hydraulic servo valves A and B and the oil pressure high-selection device on oil supply lines A and B, respectively, to measure the outlet oil pressure of electro-hydraulic servo valves A and B. Electro-hydraulic servo position valves A and B output two control oil paths, A and B, respectively, to the high-pressure selector. After high-pressure selection and voting, the high-pressure selector outputs the final actual control oil pressure to the output control oil to control the power cylinder, driving the regulating valve. The control oil pressure sensor is located on the outlet side of the high-pressure selector and is used to measure the final actual control oil pressure of the redundant electro-hydraulic servo control system. Five pressure sensors, namely supply oil pressure A, supply oil pressure B, control oil pressure A, control oil pressure B, and control oil pressure, transmit 4-20mA measurement signals to the electronic monitoring device located in the central control room through hard-wiring. The electronic monitoring device simultaneously collects the regulating valve position feedback signals A and B from the field regulating valves and the communication signals regulating valve commands A and B from other controllers. After logical judgment, these signals output control commands, which control the opening and closing of shut-off valves A and B through a hard-wiring circuit.

[0097] It should be noted that the above embodiments are not intended to limit the scope of protection of the present invention. Equivalent transformations or substitutions made based on the above technical solutions all fall within the scope of protection of the claims of the present invention.

Claims

1. A redundant electro-hydraulic servo control method for a steam turbine, characterized in that, The method includes the following steps: Step 1: Install a shut-off solenoid valve on each of the two electro-hydraulic converter's oil supply lines. During normal operation, the shut-off solenoid valve is fully open and de-energized. When the shut-off condition is met, it is energized and closes. Even if the control power is lost, the shut-off solenoid valve will not close due to power failure, ensuring unobstructed oil flow. Step 2: Install five pressure sensors on the outlet hydraulic pipeline: supply oil pressure sensor A for electro-hydraulic converter A, control oil pressure sensor A for electro-hydraulic converter A, supply oil pressure sensor B for electro-hydraulic converter B, control oil pressure sensor B for electro-hydraulic converter B, and actual control oil pressure sensor. Step 3: Add a PLC-based electronic device to comprehensively monitor and control the redundant electro-hydraulic conversion device. Step 4: Acquire signals such as oil supply pressure, control oil pressure, valve position, and power status via hard-wiring and output shut-off valve commands and system alarm signals; acquire information from the electro-hydraulic control controller via communication. Step 5: Set up a screen to engage and disengage the electromagnetic shut-off valve in the oil inlet pipeline, and display the engagement and disengagement status of the electromagnetic valve. Step Six: When the unit is running, the electronic monitoring device continuously monitors the oil pressure control commands output by the turbine control system and the oil pressure difference output by each electro-hydraulic converter. If the oil pressure difference of a certain electro-hydraulic converter is higher than the set difference and remains higher for a certain period of time, it can be determined that this electro-hydraulic converter is stuck, and the stuck position is at the high oil pressure output position. The monitoring system then outputs a cut-off command to cut off the cut-off valve on the oil supply pipeline of this faulty electro-hydraulic converter, thereby reducing the output oil pressure of this faulty electro-hydraulic converter, exiting the redundancy mechanism, and avoiding the output of incorrect valve commands to the turbine. Step 7: The operator selects whether to enable or disable the shut-off valve function based on production needs. When enabled, it indicates that the PLC control system has the function of shutting off the solenoid valve. When the conditions in Step 6 are met, the corresponding solenoid valve will be shut off. When the function is disabled, even if all the above conditions are met, the PLC control system will no longer have the function of shutting off the solenoid valve. Step 8: Set alarm information, including low oil pressure, speed probe failure, and execution command failure. The operator can quickly find the cause of the failure and accurately locate the fault location through the alarm information.

2. The redundant electro-hydraulic servo control method for a steam turbine according to claim 1, characterized in that, In step one, a shut-off solenoid valve A and a shut-off solenoid valve B are installed on the oil pressure pipelines of the two electro-hydraulic servo position valves. During normal operation, shut-off solenoid valves A and B are in a fully open state without power. When the shut-off condition is met, shut-off solenoid valve A or B is automatically energized to close the valve and cut off the oil supply to the electro-hydraulic servo position valve. Even if the control power is lost, the shut-off solenoid valve will not close due to power failure, ensuring that the oil supply circuit is unobstructed.

3. The redundant electro-hydraulic servo control method for a steam turbine according to claim 1, characterized in that, In step three, a PLC-based control system is added to comprehensively monitor and control the redundant electro-hydraulic conversion device. The control system consists of a CPU3152PN / DP module, an analog input AI8×12bit module, an analog output AO8×12bit module, a digital input DI16×DC24V module, a digital output DO16×DC24V / 0.5A module, and a CP341 communication module. The CPU315-2PN / DP is the control core of the system and communicates with the KTP900PN human-machine interface touch screen (HMI) via an RJ45 Ethernet interface. The PLC communicates with the WOODWARD 505 controller via Modbus through the DB15 pin interface of the CP341. The PLC acts as the master station, and the 505 controller acts as the slave station. The operator operates and monitors the WSM redundant electro-hydraulic servo valve through the HMI.

4. The redundant electro-hydraulic servo control method for steam turbines according to claim 2, characterized in that, Step 5: Set up the screen to engage and disengage the electromagnetic shut-off valve of the oil inlet pipeline, and display the engagement and disengagement status of the electromagnetic valve. When the system does not need to engage the electromagnetic valve, simply click the disengagement button on the screen. The screen also configures the corresponding measuring points to monitor the oil supply pressure A and B, control oil pressure A and B, actual control oil pressure, valve command A and B, and valve position feedback A and B. The screen displays the current status of each signal. When a signal fails, the corresponding line will turn red.

5. The redundant electro-hydraulic servo control method for a steam turbine according to claim 3, characterized in that, In step six, The logic decision strategy for shutting off control valve A is as follows: If the following conditions are met simultaneously, the PLC will determine that spool valve A is stuck in the oil supply position and shut off control valve A: 1) The difference between the control oil pressure and the control oil pressure B is greater than 4% of the supply oil pressure A. 2) The difference between control oil pressure A and control oil pressure B is greater than 4% of the supply oil pressure A. 3) The difference between the gate position feedback A (LVDTA) and the gate instruction A (505) is greater than 4% of the gate instruction A. 4) The difference between the gate position feedback B (LVDTB) and the gate instruction B (505) is greater than 4% of the gate instruction B. 5) The valve position feedback signal A is normal. 6) The regulating gate command A signal is normal. 7) The valve position feedback signal B is normal. 8) The B signal of the regulating gate is normal. 9) The oil pressure supplying the electro-hydraulic servo position valve B is normal. 10) The outlet oil pressure (control oil B pressure) of the electro-hydraulic servo position valve B is normal. 11) The shut-off valve B command for electro-hydraulic servo position valve B is in the "not shut off" state. Logical decision-making strategy for shutting off control valve B: If the following conditions are met simultaneously, it will be determined that valve B is stuck in the oil supply position, and the PLC will cut off control of valve B. 1) The difference between the control oil pressure and control oil pressure A is greater than 4% of the supply oil pressure B. 2) The difference between control oil pressure B and control oil pressure A is greater than 4% of the supply oil pressure B. 3) The difference between the gate position feedback A (LVDTA) and the gate instruction A (505) is greater than 4% of the gate instruction A. 4) The difference between the gate position feedback B (LVDTB) and the gate instruction B (505) is greater than 4% of the gate instruction B. 5) The valve position feedback signal A is normal. 6) The regulating gate command A signal is normal. 7) The valve position feedback signal B is normal. 8) The B signal of the regulating gate is normal. 9) The oil pressure supplying the electro-hydraulic servo position valve A is normal. 10) The outlet oil pressure (control oil A pressure) of the electro-hydraulic servo position valve A is normal. 11) The shut-off valve A command of electro-hydraulic servo position valve A is in the "not shut off" state.

6. A redundant electro-hydraulic servo control system for a steam turbine, characterized in that, The redundant electro-hydraulic servo control method for a steam turbine according to any one of claims 1-5, wherein the control system includes... Oil supply line A, oil supply line B, shut-off valve A, shut-off valve B, oil supply pressure A, oil supply pressure B, control oil pressure A, control oil pressure B, control oil pressure, electro-hydraulic servo valve A, electro-hydraulic servo valve B, high-pressure selector, electronic monitoring device, valve command A, valve position feedback A, valve command B and valve position feedback B, oil supply line A supplies oil to electro-hydraulic servo valve A, oil supply line B supplies oil to electro-hydraulic servo valve B, shut-off valve A is located on the oil supply line The input sensor of electro-hydraulic servo position valve A is located on line A. The shut-off valve B is located on the input sensor of electro-hydraulic servo position valve B on line B. Both valves are used to shut off the oil supply to the electro-hydraulic servo position valve in abnormal situations. Oil supply pressure sensors A and B are located on lines A and B respectively, between the shut-off valves A and B and the electro-hydraulic servo position valves A and B, measuring the inlet oil pressure of the electro-hydraulic servo position valves A and B. Control oil pressure sensors A and B are located on lines A and B respectively, between the electro-hydraulic servo position valves A and B and the electro-hydraulic servo position valves A and B. In the middle of the high-pressure selector, the outlet oil pressure of electro-hydraulic servo position valves A and B is measured. Electro-hydraulic servo position valves A and B respectively output two control oils A and B to the high-pressure selector. After high-pressure selection and voting, the high-pressure selector outputs the final actual control oil pressure to the output control oil to control the power cylinder and drive the regulating valve. The control oil pressure sensor is located on the outlet side of the high-pressure selector and is used to measure the final actual control oil pressure of the redundant electro-hydraulic servo control system. Five pressure sensors, namely oil supply pressure A, oil supply pressure B, control oil pressure A, control oil pressure B, and control oil pressure, transmit the 4-20mA measurement signal to the electronic monitoring device located in the central control room through hard-wiring. The electronic monitoring device simultaneously collects the regulating valve position feedback signals A and B from the field regulating valve and the communication signals regulating valve commands A and B from other controllers. After logical judgment, these signals output control commands, which control the opening and closing of shut-off valves A and B through hard-wiring circuits.

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