Online verification device for LVDT (linear variable differential transformer) of steam turbine control valve of thermal power plant

Abstract

The utility model discloses an on-line verification device used for a thermal power plant steam turbine control valve LVDT, and relates to the technical field of electrical equipment maintenance and detection. The device comprises an online verification device body, a wiring terminal strip, a primary coil, a secondary coil, a demodulator, a comparator, a signal generator, a graduated scale, a fixing device, a green light, a red light and the like. The full-stroke opening degree of the steam turbine control valve is recorded on the graduated scale and locked, an accurate reference is provided for verification of the LVDT, and high-precision online verification of the LVDT is achieved in combination with a signal adjusting system and an automatic indicating system. Compared with a traditional method, the device has the advantages that the debugging error range is reduced from + / -1.5 mm to + / -0.2 mm, the debugging success rate is remarkably increased, shutdown is not needed, and the operation and maintenance efficiency and economical efficiency of equipment are remarkably improved.

Description

Technical Field

[0001] The utility model relates to the technical field of power equipment maintenance and detection, and specifically discloses an on-line calibration device that can be used for the LVDT of the steam turbine governing valve in a thermal power plant. Background Art

[0002] In a thermal power plant, the steam turbine governing valve is a key device for controlling the steam flow rate and the unit power output. Its normal operation is crucial for the safety and stability of the unit. An LVDT (Linear Variable Differential Transformer) is usually installed in the steam turbine governing valve to accurately measure the opening of the governing valve. The LVDT is a sensor that converts mechanical displacement into an electrical signal, and its output signal directly affects the regulation accuracy of the steam turbine governing valve. However, the existing debugging and calibration of LVDT can usually only be carried out when the unit is shut down. This means that if the LVDT fails or has an error during the operation of the unit, it is necessary to shut down the unit for debugging, which not only affects the production efficiency of the power plant, but also may cause economic losses and equipment wear. Therefore, how to achieve on-line calibration of LVDT without shutting down the unit has become an important issue in the current equipment maintenance of power plants. An existing energy-saving control system for electrical engineering automation applicable to thermal power plants (publication number: CN115509195A) has at least the following drawbacks:

[0003] 1. The existing steam turbine governing valve belongs to the main equipment of the power plant, and its LVDT is generally debugged after the unit is shut down. If an LVDT failure occurs during the operation of the unit, since the change in the opening of the steam turbine governing valve will greatly affect the stable operation of the unit, such problems are very difficult to handle. Therefore, there is an urgent need for a device that can achieve on-line calibration of LVDT during the operation of the generator set. Summary of the Utility Model

[0004] The main purpose of the utility model is to provide an on-line calibration device that can be used for the LVDT of the steam turbine governing valve in a thermal power plant, which can effectively solve the problems in the background art.

[0005] To achieve the above purpose, the technical solution adopted by the utility model is: an on-line calibration device that can be used for the LVDT of the steam turbine governing valve in a thermal power plant, including the on-line calibration device body. A terminal block is installed on the on-line calibration device body. The terminal block is connected to the internal secondary coil 1 through an LVDT cable. A secondary coil 2 is installed on the right side of the secondary coil 1. A primary coil is installed on the right side of the secondary coil 2. A demodulator is electrically connected to the lower side of the secondary coil 2. The demodulator is connected to a comparator through a cable. The comparator is connected to a signal generator through a cable.

[0006] Preferably, a green light is electrically connected above the comparator.

[0007] Preferably, a red light is electrically connected to the other side above the comparator.

[0008] Preferably, a fixing device is installed in front of the on-line calibration device body.

[0009] Preferably, a scale is engraved above the fixing device.

[0010] Preferably, the green light is installed above the on-line calibration device body, and a red light is installed beside the green light.

[0011] Compared with the prior art, the utility model has the following beneficial effects:

[0012] 1. In the utility model, the full stroke opening of the steam turbine governing valve is recorded on the scale and locked, providing an accurate reference for the calibration of the LVDT. The LVDT is fixed on a special device to ensure the stability of its position during the debugging process. The signal conditioning system demodulates the signal output by the LVDT into a voltage signal, and generates reference signals of different voltage levels through the connected signal generator and comparator. The operator can manually adjust the LVDT sleeve to ensure that the initial voltage reading is close to 0 VDC, and the green light indicates whether the operation meets the requirements. The LVDT is adjusted gear by gear on the scale, moving 20% each time and correspondingly adjusting the output voltage of the signal generator. By observing the green light throughout the process, it can be confirmed whether the debugging of the LVDT is qualified. Finally, the LVDT is installed on the steam turbine governing valve to ensure the accuracy and safety during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic diagram of the overall structure of the utility model;

[0014] Figure 2 is a sectional view of the interior of the utility model;

[0015] In the figure: 1, on-line calibration device body; 2, fixing device; 3, scale; 4, green light; 5, red light; 6, terminal block; 7, LVDT cable; 8, primary coil; 9, secondary coil 2; 10, secondary coil 1; 11, demodulator; 12, comparator; 13, signal generator; 14, cable. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] In order to make the technical means, creative features, achieved purposes and effects of the utility model easy to understand, the utility model will be further described below in conjunction with specific embodiments.

[0017] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0018] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "provided with", "connected", etc. shall be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0019] Embodiment

[0020] Please refer to Figure 1-2 , the present utility model provides a technical solution:

[0021] An on-line calibration device that can be used for the LVDT of the steam turbine governing valve in a thermal power plant, including the on-line calibration device body. A terminal block is installed on the on-line calibration device body. The terminal block is connected to the internal secondary coil 1 through an LVDT cable. A secondary coil 2 is installed on the right side of the secondary coil 1. A primary coil is installed on the right side of the secondary coil 2. A demodulator is electrically connected to the lower side of the secondary coil 2. The demodulator is connected to a comparator through a cable. The comparator is connected to a signal generator through a cable. A green light is electrically connected above the comparator. A red light is electrically connected to the other side above the comparator. A fixing device is installed in front of the on-line calibration device body. A scale is engraved above the fixing device. The green light is installed above the on-line calibration device body, and a red light is installed beside the green light.

[0022] It should be noted that, first of all, for the present utility model, by recording and locking the full stroke opening of the steam turbine governing valve on a scale, an accurate reference is provided for the calibration of the LVDT. The LVDT is fixed on a special device, ensuring the stability of its position during the debugging process. The signal conditioning system demodulates the signal output by the LVDT into a voltage signal, and generates reference signals of different voltage levels through the connected signal generator and comparator. The operator can manually adjust the LVDT sleeve to ensure that the initial voltage reading is close to 0 VDC, and the green light indicates whether the operation meets the requirements. The LVDT is adjusted step by step on the scale, moving 20% each time and correspondingly adjusting the output voltage of the signal generator. By observing the lighting situation of the green light throughout the process, it can be confirmed whether the debugging of the LVDT is qualified. Finally, the LVDT is installed on the steam turbine governing valve to ensure the accuracy and safety during operation.

[0023] It should be noted that, for the present utility model, by recording and locking the full stroke opening of the steam turbine governing valve on a scale, an accurate reference is provided for the calibration of the LVDT, greatly improving the operation accuracy. The LVDT is fixed on a specially designed device, ensuring the stability of its position during the debugging process, and avoiding the deviation caused by vibration or unstable installation of traditional equipment. The error range of traditional LVDT debugging is usually within ±1.5 mm, while the present utility model controls the error within ±0.2 mm through an accurate fixing device, significantly improving the debugging accuracy. In addition, the signal conditioning system demodulates the signal output by the LVDT into a voltage signal, and then generates reference signals of different voltage levels through the signal generator and comparator, making the debugging process more sensitive and accurate. The traditional system usually requires multiple manual adjustments to ensure the stability of the signal, while in the actual operation of the present utility model, the success rate of the first adjustment reaches more than 85%, far higher than about 50% of traditional equipment, greatly reducing the debugging time, and the average debugging time is shortened by 40%. The operator can manually adjust the LVDT sleeve to ensure that the initial voltage reading is close to 0 VDC, and the green light indicates whether it meets the requirements. Whenever the LVDT is adjusted step by step on the scale, the signal generator outputs voltages of 2 VDC, 4 VDC, 6 VDC, 8 VDC, and 10 VDC in sequence, and by observing the lighting situation of the green light throughout the process, it can be confirmed whether the debugging of the LVDT is qualified. Compared with the prior art, the present utility model avoids the errors caused by manual operation, the debugging qualification rate is increased by 30%, the accuracy of each debugging is higher, and the rework rate is reduced.

[0024] It should be noted that the following is a comparison table of experimental data between the present utility model and traditional equipment:

[0025] Comparison items Prior art The present utility model Superiority Debugging error range ±1.5 mm ±0.2 mm The debugging accuracy is increased by 7 times and the error is significantly reduced Success rate of the first adjustment About 50% Over 85% The success rate of the first adjustment is increased by 35% and the debugging time is reduced Average debugging time About 1 hour About 36 minutes The debugging time is shortened by 40% and the efficiency is improved Qualified rate of debugging About 70% Over 90% The qualified rate of debugging is increased by 20% and the rework is reduced Single rework rate 15%-20% Less than 5% The rework rate is reduced by about 75% and the number of reworks is reduced

[0026] The foregoing has shown and described the basic principles, main features and advantages of the present utility model. Those skilled in the art should understand that the present utility model is not limited by the above embodiments, and what is described in the above embodiments and the specification only illustrates the principles of the present utility model. Without departing from the spirit and scope of the present utility model, the present utility model will have various changes and improvements, and all these changes and improvements fall within the scope of the present utility model claimed. The scope of protection claimed by the present utility model is defined by the appended claims and their equivalents.

Claims

1. An online calibration device for a steam turbine regulating valve LVDT in a thermal power plant, comprising an online calibration device body (1), characterized in that: A terminal block (6) is installed on the body (1) of the online verification device. The terminal block (6) is connected to an internal secondary coil 1 (10) via an LVDT cable (7). A secondary coil 2 (9) is installed on the right side of the secondary coil 1 (10). A primary coil (8) is installed on the right side of the secondary coil 2 (9). A demodulator (11) is electrically connected to the lower side of the secondary coil 2 (9). The demodulator (11) is connected to a comparator (12) via a cable (14). The comparator (12) is connected to a signal generator (13) via a cable (14).

2. The online calibration device for LVDT of a steam turbine regulating valve in a thermal power plant according to claim 1 is characterized in that: The comparator (12) is electrically connected to the green light (4) at the top.

3. The online calibration device for LVDT of a steam turbine regulating valve in a thermal power plant according to claim 1 is characterized in that: The other side above the comparator (12) is electrically connected to the red light (5).

4. The online calibration device for LVDT of a steam turbine regulating valve in a thermal power plant according to claim 1 is characterized in that: A fixing device (2) is installed in front of the on-line verification device body (1).

5. The online calibration device for LVDT of a steam turbine regulating valve in a thermal power plant according to claim 4 is characterized in that: A scale (3) is engraved above the fixing device (2).

6. The online calibration device for LVDT of a steam turbine regulating valve in a thermal power plant according to claim 2 is characterized in that: The green light (4) is installed above the on-line calibration device body (1), and a red light (5) is installed next to the green light (4).

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