Low-pressure cylinder blade radial displacement detection system of nuclear turbine generator set
Through the principle of non-contact passive eddy current induction detection and signal processing technology, the problems of unstable accuracy and poor environmental adaptability in the blade displacement detection of low-pressure cylinders of nuclear power turbine generator sets are solved, and high-precision and low-maintenance blade displacement measurement is achieved.
Patent Information
- Application Number
- CN202411214065.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-31
- Publication Date
- 2025-01-03
AI Technical Summary
The prior art has problems in the detection of radial displacement of low-pressure cylinder blades in nuclear power turbine generator sets, which are unstable in measurement accuracy, complex equipment and susceptible to environmental factors, especially in high temperature and high humidity environments, which are difficult to effectively monitor the slight displacement changes of the blades.
Using the non-contact passive eddy current induction detection principle, a magnetic field is generated through the energized metal coil in the probe, and the blade displacement is converted into a voltage signal by using the eddy current effect, and it is used to process low-pass filtering and high-pass filtering, AD conversion and voltage and displacement. The accurate displacement value is calculated based on the table.
It realizes high-precision measurement of blade displacement in high temperature and high humidity environments, eliminates interference from environmental factors, reduces maintenance needs, and improves system flexibility and maintainability.
Smart Images
Figure CN119245492A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of blade displacement detection, and more specifically, to a system for detecting radial displacement of blades of a low-pressure cylinder of a nuclear power steam turbine generator set. Background Art
[0002] As a vital power equipment in the power generation system, the stable operation of the steam turbine is directly related to the safety and efficiency of the entire power system. As a key component of the steam turbine, the steam turbine blades are subjected to extreme working environments of high temperature, high pressure and high-speed rotation, and their working conditions have a direct impact on the performance of the steam turbine. In particular, the blades of the low-pressure cylinder of the nuclear power steam turbine generator set are particularly important to monitor their radial displacement due to the complex working environment.
[0003] During the operation of the steam turbine, the length of the blade is not only affected by the high temperature and pressure inside the turbine, but also by the centrifugal force generated by the rotation. These factors may cause the blade to shift. If the tiny displacement of the blade is not monitored and corrected in time, it may gradually accumulate into a larger deformation or damage, thereby affecting the overall operating efficiency and safety of the steam turbine. Therefore, accurate measurement of the displacement of the turbine blade is of great significance for preventing blade failures and ensuring the stable operation of the unit.
[0004] At present, the main methods for measuring blade displacement include capacitive ranging and optical ranging. However, these methods have certain limitations in the application of low-pressure cylinders of nuclear power steam turbine generator sets. For example, capacitive ranging is greatly affected by changes in ambient temperature, humidity and dielectric constant, and it is difficult to maintain measurement accuracy in the high temperature and high humidity environment of nuclear power steam turbines; and although optical ranging has high accuracy, the equipment is complex, expensive, and easily affected by environmental factors such as dust and water mist, and it is difficult to maintain.
[0005] Therefore, in order to solve the above technical problems, the present invention proposes a radial displacement detection system for low-pressure cylinder blades of a nuclear power steam turbine generator set. Summary of the invention
[0006] In view of the deficiencies in the prior art, the present invention aims to provide a system for detecting radial displacement of blades of a low-pressure cylinder of a nuclear power steam turbine generator set.
[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a nuclear power steam turbine generator set low-pressure cylinder blade radial displacement detection system, a displacement detection module, a non-contact measurement method, a blade displacement detection probe adopts a passive eddy current induction detection principle, a magnetic field is generated by an energized metal coil in the probe, when the blade passes through the magnetic field, according to the magnetic field induction law, an eddy current effect will be formed in the blade, the eddy current formed in the blade will offset part of the magnetic field energy generated by the probe metal, change the impedance of the metal coil in the probe, when the external conditions remain unchanged, the change in the impedance of the probe metal coil is only related to the displacement distance of the turbine blade, thereby converting the displacement value of the blade into a voltage signal;
[0008] The displacement processing module is used to power the displacement detection module and process the blade displacement voltage signal transmitted by the displacement detection module. The voltage signal processing system is equipped with a signal preprocessing circuit to perform low-pass filtering and high-pass filtering on the displacement voltage signal to filter out possible interference signals, and convert the processed voltage signal into a digital signal through an AD converter and transmit it to the blade displacement calculation software.
[0009] The displacement calculation module obtains the displacement detection module from the displacement processing module, and calculates the displacement value corresponding to the current voltage of the blade through the voltage and displacement comparison table calibrated in advance by the probe. Figure 1 The displacement calculation module searches for the voltage at the displacement voltage value obtained at the current displacement voltage value. Figure 1 The voltage interval position in the linear table, the two known linear points above and below the interval, calculate the linear correspondence between the current voltage and displacement, where the two constants k and y are calculated through Figure 1 The linear table is used for calculation (y: displacement value, unit: mm; x: displacement power value, unit: V); T0 is the initial distance from the displacement detection module when the turbine blade is initially installed, in mm. The T0 value is obtained by manual blade distance calibration during the first measurement and installation. The displacement value of the current blade can be calculated.
[0010] Furthermore, the displacement detection module adopts the passive eddy current ranging principle to test the displacement of the turbine blades. The probe module adopts a probe diameter of 25mm, and the linear range of the probe module can reach 30mm. The displacement detection module adopts the passive eddy current displacement measurement principle. After the metal coil placed in the displacement detection module is energized, it generates magnetic field energy. When the turbine blades pass through the magnetic field, because the turbine blades are permeable metals, according to the principle of electromagnetic induction, an eddy current effect will be formed inside the turbine blades. The eddy current formed in the blades will offset part of the magnetic field energy generated by the probe metal and change the impedance of the metal coil in the probe. When the external conditions remain unchanged, the change in the impedance of the probe metal coil is only related to the displacement distance of the turbine blades, thereby converting the displacement position of the blades into a voltage signal.
[0011] Furthermore, in the displacement processing module, the voltage signal preprocessing circuit inside the system includes a low-pass filter and a high-pass filter, which are used to filter out low-frequency and high-frequency interference signals in the signal. The low-pass filter and the high-pass filter can be logically programmed according to the actual situation on site, and the filtering frequency can be freely changed; after the blade displacement voltage signal passes through the preprocessing circuit, it enters the AD conversion module circuit of the displacement processing module. The module circuit adopts a 24-bit AD converter with a sampling rate of 200Kbps, which converts the voltage analog of the blade displacement into a digital signal and transmits it to the displacement calculation module.
[0012] Furthermore, after the displacement calculation module obtains the voltage value of the displacement detection module from the displacement processing module, the displacement calculation module calculates the displacement value corresponding to the current voltage of the blade through a voltage and displacement comparison table calibrated in advance by the probe.
[0013] Compared with the prior art, the present invention has the following beneficial effects:
[0014] 1. The present invention has strong environmental adaptability:
[0015] The non-contact passive eddy current induction measurement principle can effectively eliminate the influence of the high temperature and high humidity environment inside the nuclear power turbine on the measurement accuracy. Compared with capacitive ranging, this method is not affected by changes in ambient temperature, humidity and dielectric constant, ensuring the stability and accuracy of the measurement results.
[0016] 2. The present invention has high measurement accuracy:
[0017] Through the precise voltage and displacement linear correspondence table, combined with the blade displacement calculation software system, the voltage signal can be accurately converted into the radial displacement value of the blade, realizing high-precision measurement of the blade displacement.
[0018] 3. The present invention is easy to maintain:
[0019] The non-contact measurement method avoids direct contact with the blades, reducing the maintenance requirements due to wear or damage. At the same time, the low-pass filter and high-pass filter inside the system can be logically programmed according to the actual situation on site, and the filter frequency can be freely changed, which improves the flexibility and maintainability of the system. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:
[0021] Figure 1 Schematic diagram of the voltage versus displacement comparison of the present invention. DETAILED DESCRIPTION
[0022] The present invention provides a nuclear power steam turbine generator set low-pressure cylinder blade radial displacement detection system, and this embodiment provides a nuclear power steam turbine generator set low-pressure cylinder free blade displacement detection method. The displacement detection module converts the displacement value of the steam turbine blade into a voltage value and outputs it to the displacement processing module; after signal preprocessing, the displacement processing module converts the displacement voltage signal into a digital signal through the AD conversion module and transmits it to the displacement calculation module; the displacement calculation module calculates the displacement value of the current blade according to the voltage and displacement comparison table calibrated in advance by the displacement detection module, and transmits the displacement value of the steam turbine blade to the blade displacement display system.
[0023] In order to enable those skilled in the art to have a clearer understanding and recognition of the present invention, a method for detecting radial displacement of a low-pressure cylinder blade of a nuclear power steam turbine generator set is described in detail below:
[0024] A method for detecting radial displacement of blades of a low-pressure cylinder of a nuclear power steam turbine generator set comprises a displacement detection module, a displacement processing module, a displacement calculation module and a blade displacement display system.
[0025] The displacement detection module adopts a non-contact measurement method. The blade displacement detection probe adopts the passive eddy current induction detection principle. A magnetic field is generated by the energized metal coil in the probe. When the blade passes through the magnetic field, an eddy current effect will be formed in the blade according to the magnetic field induction law. The eddy current formed in the blade will offset part of the magnetic field energy generated by the probe metal and change the impedance of the metal coil in the probe. When the external conditions remain unchanged, the change in the impedance of the probe metal coil is only related to the displacement distance of the turbine blade, thereby converting the displacement value of the blade into a voltage signal.
[0026] The displacement processing module has built-in low-pass filter circuit and high-pass filter circuit to pre-process the voltage signal of blade displacement and remove interference signals. The filter parameters can be adjusted according to the actual site. The displacement voltage signal pre-processed by the displacement processing module is converted into a digital signal through the 24-bit AD conversion module in the displacement processing module and transmitted to the displacement calculation module.
[0027] After receiving the signal transmitted by the displacement processing module, the displacement calculation module calculates the displacement value corresponding to the current voltage of the blade through the voltage and displacement comparison table calibrated in advance by the probe. Figure 1It is the comparison table of voltage and displacement of the actual displacement detection module. The displacement calculation module searches for the voltage interval position in the voltage and displacement comparison table according to the currently acquired displacement voltage value, and calculates the linear correspondence between the current voltage and displacement by taking the two known linear points above and below the interval. The two constants k and y are calculated through the voltage and displacement comparison table (y: displacement value, unit mm; x: displacement power value, unit V); T0 is the initial distance from the displacement detection module when the turbine blade is initially installed, in mm. The T0 value is obtained by manual blade distance calibration during the first measurement and installation. The displacement value of the current blade can be calculated, and b is the initial deviation value of the sensor when the voltage x is 0.
[0028] The voltage and displacement comparison table is set in advance in the displacement calculation module. The implementation process of the radial displacement detection method of the low-pressure cylinder blade of a nuclear power steam turbine generator set is as follows:
[0029] The displacement detection module uses the measurement principle of eddy current ranging to measure the displacement distance of the blade in a non-contact manner and convert the displacement distance of the blade into a voltage signal.
[0030] The displacement processing module has built-in low-pass filtering module and high-pass filtering module, which are used to pre-process the blade displacement voltage signal transmitted from the blade displacement monitoring probe module, and convert the displacement voltage signal into a digital signal through a 24-bit AD.
[0031] After receiving the inter-blade voltage transmitted by the displacement processing module, the displacement calculation module calculates the blade displacement distance value corresponding to the current blade displacement voltage according to the comparison table of the voltage and displacement of the displacement detection module, and displays the blade displacement value.
[0032] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in the industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with the profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.
Claims
1. A nuclear power steam turbine generator set low pressure cylinder blade radial displacement detection system, characterized in that: include: The displacement detection module is used to detect the displacement of the blade and convert the displacement value into a voltage signal; The displacement processing module is used to receive and process the voltage signal sent by the displacement detection module, convert the voltage signal into a digital signal, and also provide power for the displacement detection module; The displacement calculation module is used to obtain the digital signal processed by the displacement processing module and calculate the position value of the blade according to the voltage and displacement comparison table. The calculation formula is: y=(kx+b)-T0 Wherein, k is a constant, y is the displacement value, x is the displacement voltage value, b is the initial deviation value of the sensor when the voltage x is 0, and T0 is the initial distance from the displacement detection module when the turbine blade is initially installed.
2. A nuclear power steam turbine generator set low pressure cylinder blade radial displacement detection system according to claim 1, characterized in that: The displacement detection module adopts passive eddy current induction non-contact detection.
3. A nuclear power steam turbine generator set low pressure cylinder blade radial displacement detection system according to claim 1, characterized in that: The voltage and displacement comparison table is set in advance in the displacement calculation module.
4. A voltage signal processing method, applied to a nuclear power steam turbine generator low-pressure cylinder blade radial displacement detection system as claimed in any one of claims 1 to 3, characterized in that: The processing of the voltage signal in the displacement processing module includes the following steps: A. Voltage signal preprocessing, through low-pass filter and high-pass filter, is used to filter out low-frequency and high-frequency interference signals in the signal; B. After the voltage signal passes through the preprocessing circuit, it enters the AD conversion module circuit of the blade displacement voltage signal processing system; C. Convert the voltage analog of blade displacement into digital signal and transmit it to the blade displacement calculation software system.
5. The method for processing a voltage signal according to claim 4, characterized in that: The low-pass filter and the high-pass filter can be logically programmed according to actual conditions on site, and the filter frequency can be freely changed.
6. A nuclear power steam turbine generator set low pressure cylinder blade radial displacement detection system according to claim 3, characterized in that: After the displacement processing module detects the voltage value detected by the displacement detection module, the displacement value corresponding to the current voltage of the blade is calculated through a comparison table of voltage and displacement calibrated in advance by the probe.