Online calibration method for steam turbine control valve

Abstract

The invention discloses an online calibration method for a steam turbine control valve, and relates to the technical field of steam turbine control valves. The online calibration method for the steam turbine control valve comprises the following specific operation steps: S1, cutting off a power loop; it is ensured that the power loop is in a non-operation state, and the power loop is prevented from adjusting other valves when a faulty valve is debugged in the later period. And S2, reducing the load. And the load is slowly reduced to 65% or below of the upper limit of the unit load, and a load rising space is reserved for later opening of the fault control valve. According to the online calibration method for the turbine control valve, the defects in the prior art can be overcome, online calibration of the control valve is achieved, the economical efficiency of a unit is improved, online calibration work of the control valve is smoothly completed in a forced, open-loop, calibration and closed-loop mode, and accidents such as pipeline vibration, sealing leakage and load shedding are effectively avoided; the problems of two LVDT faults, control valve LVDT connecting rod breakage and the like during operation of the steam turbine are solved, and the economical efficiency of the steam turbine is improved.

Description

Technical Field

[0001] The invention relates to the technical field of steam turbine regulating valves, and in particular to an online calibration method for steam turbine regulating valves. Background Art

[0002] The turbine regulating valve is a valve that is used in conjunction with the DEH control system to regulate the internal fluid of the turbine and control the output power, speed and efficiency of the unit. In order to ensure the stability of the above functions, the turbine regulating valve needs to be calibrated.

[0003] The steam turbine valve position calibration involves two operations: open-loop zero position and open-loop full opening. Open-loop zero position is an operation in which the valve is quickly closed after receiving a command at any position; open-loop full opening is an operation in which the valve is quickly opened to the upper limit of the stroke after receiving a command at any position. The above two operations when the unit is running will cause the valve to be suddenly opened or closed, causing damage to the equipment such as pipeline vibration, seal leakage, load rejection and even unplanned shutdown. Therefore, the power industry standard "DL / T 774-2015" recommends that the steam turbine valve position calibration be carried out when the unit is shut down.

[0004] In the Patent Star system, a novel search was conducted based on the search type "throttle calibration / online", and two search results were obtained: "A power plant online calibration demonstration device", application number: CN201922199038.7; "A steam turbine throttle online calibration method", application number: CN201711359782.8.

[0005] A comparative analysis with the first search result shows that it is a utility model patent, the invention is a physical device for demonstration and training purposes, and the present invention is an operating method derived from existing equipment.

[0006] A comparative analysis with the second search result shows that the present invention has the same invention purpose as that of the invention, but has specific differences in the implementation method. Specifically, the search result requires manual adjustment of the LVDT position and then automatic calibration using the host computer, and the calibration work accuracy is low; the present invention combines the offline calibration method of the steam turbine with the online calibration method implemented by forced, open-loop debugging, closed-loop operation, etc., and the calibration accuracy is consistent with the shutdown calibration accuracy.

[0007] The legal status of the above two search results is invalid. Summary of the invention

[0008] 1. Technical issues to be resolved

[0009] In view of the deficiencies in the prior art, the present invention provides an online calibration method for a steam turbine regulating valve, which solves the problems existing in the prior art.

[0010] (II) Technical solution

[0011] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for online calibration of a steam turbine regulating valve, the operation of which is as follows:

[0012] S1: Cut off the power circuit. Ensure that the power circuit is not in operation to prevent the power circuit from regulating other valves when debugging the faulty valve later.

[0013] S2: Reduce the load. Slowly reduce the load to below 65% of the upper load limit of the unit, leaving room for load increase when the fault regulating valve is fully opened in the later stage.

[0014] S3: Forced command. Confirm that the servo valve inlet throttle is closed and force the faulty valve command to 0 to prevent abnormal operation of the faulty valve.

[0015] S4: Reinstall the primary equipment. For the two-way LVDT, reinstall and fix it. It should be noted that there are scale lines on the LVDT core, and the movement of the core cannot exceed the linear range of the coil, otherwise nonlinear values ​​will be generated.

[0016] S5: Zero position calibration. Enter VCC debugging through the host computer, let the valve enter the open loop mode, so that it is out of the closed loop state where the command and feedback are constantly compared, click the open loop zero position, and the host computer sends the corresponding signal voltage of the closing direction to the servo valve through the VCC card. At the same time, confirm the valve mechanical scale on site. The valve position should be in the mechanical zero position state. At this time, click the automatic two-way setting to write the current voltage value into the VCC card and save it to complete the valve zero position calibration.

[0017] S6: Full-scale calibration. After the zero-position calibration is completed, let the valve enter the closed-loop working state, check that the valve always has a command signal forced to 0, slowly open the servo valve throttle, and let the valve have normal operation conditions. Then give a forced command by slowly setting the number, so that the unit load slowly increases until the given forced command cannot change the valve position. At the same time, confirm the valve mechanical scale on site, and the valve position should currently be in a mechanically fully opened state. At this time, enter the VCC debugging, and send the servo valve a signal voltage corresponding to the fully opened direction through the VCC card. At this time, click the automatic dual-channel setting to write the current voltage value into the VCC card and save it, and the full-scale calibration of the valve is completed.

[0018] S7: Commissioning. After the full-scale calibration operation is completed, the valve is returned to the closed-loop normal working mode and maintained in the forced state. Taking the unit single-valve mode operation as an example, the valve opening is slowly set to close to the other valves, and then the forced state is released to complete all operations.

[0019] (III) Beneficial effects

[0020] The present invention provides a method for online calibration of a steam turbine regulating valve. It has the following beneficial effects:

[0021] The steam turbine valve online calibration method can make up for the shortcomings of the existing technology, realize the valve online calibration, improve the unit economy, and smoothly complete the valve online calibration work by using the forced, open-loop, calibration and closed-loop method, effectively avoiding accidents such as pipeline vibration, seal leakage, load rejection, etc., and solving problems such as two-way LVDT failure and valve LVDT connecting rod breakage during turbine operation, thereby improving the economy of the steam turbine;

[0022] The calibration effect is consistent with the valve adjustment when the turbine is shut down, and the calibration accuracy is high;

[0023] The online calibration of the valve can be completed smoothly, effectively avoiding accidents such as pipeline vibration, seal leakage, load shedding, etc., and has the advantages of stability and reliability;

[0024] When dealing with such problems, there is no need to shut down the plant, thus avoiding non-stop losses and effectively improving the economic efficiency of the power plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] See also Figure 1 The present invention provides a technical solution: a method for online calibration of a steam turbine regulating valve, the specific operation is as follows:

[0028] S1: Cut off the power circuit. Ensure that the power circuit is not in operation to prevent the power circuit from regulating other valves when debugging the faulty valve later.

[0029] S2: Reduce the load. Slowly reduce the load to below 65% of the upper load limit of the unit, leaving room for load increase when the fault regulating valve is fully opened in the later stage.

[0030] S3: Forced command. Confirm that the servo valve inlet throttle is closed and force the faulty valve command to 0 to prevent abnormal operation of the faulty valve.

[0031] S4: Reinstall the primary equipment. For the two-way LVDT, reinstall and fix it. It should be noted that there are scale lines on the LVDT core, and the movement of the core cannot exceed the linear range of the coil, otherwise nonlinear values ​​will be generated.

[0032] S5: Zero position calibration. Enter VCC debugging through the host computer, let the valve enter the open loop mode, so that it is out of the closed loop state where the command and feedback are constantly compared, click the open loop zero position, and the host computer sends the corresponding signal voltage of the closing direction to the servo valve through the VCC card. At the same time, confirm the valve mechanical scale on site. The valve position should be in the mechanical zero position state. At this time, click the automatic two-way setting to write the current voltage value into the VCC card and save it to complete the valve zero position calibration.

[0033] S6: Full-scale calibration. After the zero-position calibration is completed, let the valve enter the closed-loop working state, check that the valve always has a command signal forced to 0, slowly open the servo valve throttle, and let the valve have normal operation conditions. Then give a forced command by slowly setting the number, so that the unit load slowly increases until the given forced command cannot change the valve position. At the same time, confirm the valve mechanical scale on site, and the valve position should currently be in a mechanically fully opened state. At this time, enter the VCC debugging, and send the servo valve a signal voltage corresponding to the fully opened direction through the VCC card. At this time, click the automatic dual-channel setting to write the current voltage value into the VCC card and save it, and the full-scale calibration of the valve is completed.

[0034] S7: Commissioning. After the full-scale calibration operation is completed, the valve is returned to the closed-loop normal working mode and maintained in the forced state. Taking the unit single-valve mode operation as an example, the valve opening is slowly set to close to the other valves, and then the forced state is released to complete all operations.

[0035] In summary, the online calibration method for the steam turbine regulating valve can make up for the shortcomings of the existing technology, realize the online calibration of the regulating valve, improve the economic efficiency of the unit, and smoothly complete the online calibration of the regulating valve by using the forced, open-loop, calibration and closed-loop method, effectively avoiding accidents such as pipeline vibration, seal leakage, load rejection, etc., and solving problems such as two-way LVDT failure and regulating valve LVDT connecting rod breakage during steam turbine operation, thereby improving the economic efficiency of the steam turbine;

[0036] The calibration effect is consistent with the valve adjustment when the turbine is shut down, and the calibration accuracy is high;

[0037] The online calibration of the valve can be completed smoothly, effectively avoiding accidents such as pipeline vibration, seal leakage, load shedding, etc., and has the advantages of stability and reliability;

[0038] When dealing with such problems, there is no need to shut down the plant, thus avoiding non-stop losses and effectively improving the economic efficiency of the power plant.

[0039] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0040] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for online calibration of a steam turbine regulating valve, characterized in that: The specific operations are as follows: S1: Cut off the power circuit. Ensure that the power circuit is not in operation to prevent the power circuit from regulating other valves when debugging the faulty valve later. S2: Reduce the load. Slowly reduce the load to below 65% of the upper load limit of the unit, leaving room for load increase when the fault regulating valve is fully opened in the later stage. S3: Forced command. Confirm that the servo valve inlet throttle is closed and force the faulty valve command to 0 to prevent abnormal operation of the faulty valve. S4: Reinstall the primary equipment. For the two-way LVDT, reinstall and fix it. It should be noted that there are scale lines on the LVDT core, and the movement of the core cannot exceed the linear range of the coil, otherwise nonlinear values ​​will be generated. S5: Zero position calibration. Enter VCC debugging through the host computer, let the valve enter the open loop mode, so that it is out of the closed loop state where the command and feedback are constantly compared, click the open loop zero position, and the host computer sends the corresponding signal voltage of the closing direction to the servo valve through the VCC card. At the same time, confirm the valve mechanical scale on site. The valve position should be in the mechanical zero position state. At this time, click the automatic two-way setting to write the current voltage value into the VCC card and save it to complete the valve zero position calibration. S6: Full-scale calibration. After the zero-position calibration is completed, let the valve enter the closed-loop working state, check that the valve always has a command signal forced to 0, slowly open the servo valve throttle, and let the valve have normal operation conditions. Then give a forced command by slowly setting the number, so that the unit load slowly increases until the given forced command cannot change the valve position. At the same time, confirm the valve mechanical scale on site, and the valve position should currently be in a mechanically fully opened state. At this time, enter the VCC debugging, and send the servo valve a signal voltage corresponding to the fully opened direction through the VCC card. At this time, click the automatic dual-channel setting to write the current voltage value into the VCC card and save it, and the full-scale calibration of the valve is completed. S7: Commissioning. After the full-scale calibration operation is completed, the valve is returned to the closed-loop normal working mode and maintained in the forced state. Taking the unit single-valve mode operation as an example, the valve opening is slowly set to close to the other valves, and then the forced state is released to complete all operations.

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