A vibration displacement monitoring device for the stator end of a hydro turbine unit that is resistant to electromagnetic interference

Abstract

An electromagnetic interference-resistant stator end vibration displacement monitoring device for a hydro-turbine unit includes a signal sensing unit, a demodulation unit, and a signal processing unit. The signal sensing unit comprises multiple fiber Bragg grating accelerometers (FBGs) spaced apart on the stator end of the hydro-turbine unit. Each FBG is connected to the demodulation unit, which in turn is connected to the signal processing unit. In application, the FBGs measure the vibration signal at the stator end to obtain a vibration optical signal. The demodulation unit then demodulates this signal to obtain a demodulated signal. Finally, the signal processing unit uses the demodulated signal to determine the frequency and displacement value of the vibration signal. The FBGs are unaffected by high voltage and strong electromagnetic fields, resulting in high measurement accuracy. Therefore, this design is unaffected by high voltage and strong electromagnetic fields and provides accurate vibration signal measurements.

Description

Technical Field

[0001] This utility model relates to a vibration displacement monitoring device, belonging to the field of vibration monitoring technology for hydro turbine generator sets, and particularly to a vibration displacement monitoring device for the stator end of a hydro turbine generator set that is resistant to electromagnetic interference. Background Technology

[0002] When a large hydro-generator is working, the stator end is subjected to alternating electromagnetic force and vibrates continuously. Long-term excessive vibration amplitude may cause the fastening structure of the generator stator winding end to gradually loosen, the insulation of the bars to wear, and may also cause strand breakage due to mechanical fatigue. In more serious cases, it may cause a phase-to-phase short circuit accident at the end. In order to avoid the aforementioned faults or hidden dangers, it is necessary to monitor the vibration state of the stator end.

[0003] Chinese patent application number 202411843029.6, filed on December 13, 2024, discloses an intelligent monitoring system for the operating status of a water turbine, including modules for data acquisition, real-time data push, data storage, status assessment, and human-machine interaction. The data acquisition module utilizes multiple sensors to collect vibration, sway, pressure pulsation, and key phase information; the real-time data push module distinguishes data types and pushes data using WebSocket and HTTP protocols respectively; the data storage module adopts a two-layer architecture of Redis and MySQL; the status assessment module constructs an assessment index system, determines weights using the entropy weight method and improved analytic hierarchy process, and determines the operating status through degradation analysis and fuzzy comprehensive evaluation; the human-machine interaction module displays monitoring data and assessment results, providing interfaces for real-time monitoring, data query, and status assessment. Although this design uses a DP-type seismic low-frequency vibration sensor to collect vibration signals from the stator end to determine the vibration status of the stator end, it still has the following shortcomings:

[0004] The DP-type seismic low-frequency vibration sensor is an electrical sensor. In the high-voltage and strong electromagnetic field environment of a water turbine, it may be interfered with and discharge may occur, resulting in inaccurate vibration measurement of the stator end by the DP-type seismic low-frequency vibration sensor.

[0005] The information disclosed in this background section is intended only to enhance understanding of the overall background of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects and problems of existing technologies that are susceptible to interference in high-voltage and strong electromagnetic field environments, and to provide an anti-electromagnetic interference turbine stator end vibration displacement monitoring device that is not affected by high-voltage and strong electromagnetic field environments.

[0007] To achieve the above objectives, the technical solution of this utility model is:

[0008] A vibration displacement monitoring device for the stator end of a hydro turbine unit that is resistant to electromagnetic interference, the device comprising a signal sensing unit, a demodulation unit and a signal processing unit;

[0009] The signal sensing unit includes multiple fiber Bragg grating accelerometers, which are spaced apart on the side wall of the stator end of the turbine unit.

[0010] The outputs of multiple fiber Bragg grating accelerometers are connected to the input of the demodulation unit, and the output of the demodulation unit is connected to the input of the signal processing unit.

[0011] The fiber optic accelerometer sensor includes a housing and a vibration pickup structure, the vibration pickup structure being located inside the housing, and one side of the housing being connected to one end of the stator of the turbine unit.

[0012] The vibration pickup structure includes a base, a first L-shaped beam, and a mass block;

[0013] The middle part of the base is connected to the bottom of the flexible hinge, the top of the flexible hinge is connected to the bottom of the mass block, the top of the mass block is provided with a mass groove, and the bottom of the mass groove is connected to the middle of the optical fiber.

[0014] One side of the base is connected to the bottom of the first L-shaped beam, and the top of the first L-shaped beam is provided with a first beam groove. The height of the first beam groove is the same as the height of the mass groove, and the first beam groove is connected to one end of the optical fiber.

[0015] A first fiber grating is installed on the part of the optical fiber located between the mass groove and the first beam groove.

[0016] The flexible hinge has an elastic part in the middle, and both sides of the elastic part are concave structures. The concave structures are arc-shaped and recessed towards the center line of the elastic part. The width of the middle part of the elastic part is smaller than the width of the top part of the elastic part, and the width of the middle part of the elastic part is smaller than the width of the bottom part of the elastic part.

[0017] The vibration pickup structure includes a second L-shaped beam, the bottom of which is connected to the other side of the base, and the second L-shaped beam and the first L-shaped beam are symmetrically distributed along the base;

[0018] The top of the second L-shaped beam is provided with a second beam groove, the second beam groove is at the same height as the first beam groove, and the second beam groove is connected to the other end of the optical fiber;

[0019] A second fiber grating is installed on the part of the optical fiber located between the mass slot and the second beam slot.

[0020] The fiber optic accelerometer includes sensors 11, 12, 13, 14, 15, 16, 21, 22, 23, 24, 25, and 26.

[0021] Sensors No. 11, No. 12, No. 13, No. 14, No. 15, and No. 16 are distributed at intervals on the top side wall of the stator end of the turbine unit;

[0022] Sensors No. 21, No. 22, No. 23, No. 24, No. 25, and No. 26 are spaced apart on the bottom side wall of the stator end of the turbine unit.

[0023] Sensors 11, 12, and 13 are connected to the input signal of the first channel, and the output signal of the first channel is connected to the input signal of the demodulation unit.

[0024] Sensors 14, 15, and 16 are connected to the input signal of the second channel, and the output signal of the second channel is connected to the input signal of the demodulation unit.

[0025] Sensors 21, 22, and 23 are connected to the input signal of the third channel, and the output signal of the third channel is connected to the input signal of the demodulation unit.

[0026] Sensors 24, 25, and 26 are connected to the input signal of the fourth channel, and the output signal of the fourth channel is connected to the input signal of the demodulation unit.

[0027] An epoxy resin adhesive is provided between the bottom of the fiber optic accelerometer sensor and the side wall of the stator end of the turbine unit.

[0028] The top of the fiber optic accelerometer is connected to the middle of the insulating glass ribbon, and the two ends of the insulating glass ribbon are connected to the side walls of the turbine stator end.

[0029] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0030] 1. In the electromagnetic interference-resistant stator end vibration displacement monitoring device of the present invention, the device includes a signal sensing unit, a demodulation unit, and a signal processing unit. The signal sensing unit includes multiple fiber optic accelerometers (FAIs) distributed at intervals on the stator end of the turbine. All FAIs are connected to the demodulation unit, which is also connected to the signal processing unit. In application, the vibration signal at the stator end is sensed by the multiple FAIs and transmitted to the demodulation unit. The demodulation unit then demodulates the vibration signal to obtain a demodulated signal. Finally, the signal processing unit obtains the frequency and displacement values ​​of the multiple vibration signals at the stator end based on the demodulated signal. The advantages of this invention also include:

[0031] Firstly, the fiber optic accelerometer can monitor the vibration signal at the end of the stator;

[0032] Secondly, fiber optic accelerometers are not affected by high voltage or strong electromagnetic fields, so they are more accurate in measuring vibration signals.

[0033] Thirdly, the vibration signal at the stator end is measured simultaneously by multiple fiber optic accelerometer sensors, thus providing a more comprehensive measurement of the stator end.

[0034] Therefore, this invention is not affected by high voltage and strong electromagnetic field environments, and it is relatively accurate in measuring vibration signals.

[0035] 2. In the electromagnetic interference-resistant stator end vibration displacement monitoring device of this utility model, the fiber optic grating accelerometer sensor includes a housing and a vibration pickup structure. The vibration pickup structure includes a first L-shaped beam, a second L-shaped beam, a flexible hinge, a mass block, and an optical fiber. The optical fiber is fixed horizontally along the top of the first L-shaped beam, the mass block, and the second L-shaped beam. The fiber optic grating is located between the first L-shaped beam, the mass block, and the second L-shaped beam. In application, the flexible hinge is prone to elastic deformation. When the stator end vibrates, the flexible hinge and the mass block generate relative displacement with the stator end under their own inertia, thereby stretching and compressing the fiber optic grating to generate a vibration optical signal. After establishing a linear relationship between the vibration acceleration in the vibration signal and the center wavelength drift of the vibration optical signal, the vibration acceleration of the stator end can be obtained through the center wavelength drift of the vibration optical signal. The advantages of this utility model also include:

[0036] Firstly, flexible hinges are used as elastic elements. The thinnest part of the flexible hinge is prone to elastic deformation, which has the advantages of frictionless, wear-free, and highly sensitive measurement.

[0037] Secondly, the flexible hinge adopts an integrated structural design with a high inherent frequency, which helps to broaden the frequency range of the sensor.

[0038] Thirdly, the mass block can cause two fiber gratings to produce strains of opposite directions and the same magnitude. Through the publicly disclosed demodulation method, temperature compensation can be achieved while improving sensitivity.

[0039] Therefore, the measurement sensitivity of this invention is high.

[0040] 3. In this utility model's anti-electromagnetic interference hydro-turbine unit stator end vibration displacement monitoring device, there are twelve fiber optic accelerometer sensors. Six fiber optic accelerometer sensors are distributed at 60-degree intervals on the top side of the stator end, and six fiber optic accelerometer sensors are distributed at 60-degree intervals on the bottom side of the stator end. In application, multiple fiber optic accelerometer sensors are distributed at 60-degree intervals on the top and bottom side of the stator end to simultaneously measure vibration information in multiple directions of the stator end. Given the large volume of the stator, the vibration at the top and bottom may be unbalanced. Therefore, multiple fiber optic gratings are symmetrically arranged at the top and bottom of the stator end to more comprehensively capture the vibration signal of the stator end. Therefore, this utility model provides more comprehensive measurement of vibration signals.

[0041] 4. In this utility model's anti-electromagnetic interference turbine stator end vibration displacement monitoring device, every three adjacent fiber Bragg grating accelerometers are sequentially connected to the demodulation unit via the first, second, third, and fourth channels. In application, each channel is allocated to three adjacent fiber Bragg grating accelerometers, and the two are connected using a 1-to-4 fiber optic splitter. This means the vibration optical signals from the three fiber Bragg grating accelerometers are combined into one channel for transmission. This not only effectively reduces the number of channels (ordinary single-mode fiber) but also significantly increases the channel transmission capacity. Furthermore, the spectra of the vibration optical signals from the three fiber Bragg grating accelerometers do not overlap. Therefore, this utility model has a high channel transmission capacity.

[0042] 5. In the electromagnetic interference-resistant stator end vibration displacement monitoring device of this utility model, the fiber optic accelerometer sensor is fixed to the stator end with epoxy resin. The fiber optic accelerometer sensor can also be further fixed by binding with insulating glass ribbon. During application, the fiber optic accelerometer sensor is fixed with epoxy resin and insulating glass ribbon to prevent it from falling off during the operation of the turbine generator set, thus ensuring that the fiber optic accelerometer sensor can stably measure the vibration signal at the stator end for a long period. Therefore, this utility model has good stability. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the structure of this utility model.

[0044] Figure 2 yes Figure 1 A schematic diagram of the structure of the signal sensing unit.

[0045] Figure 3 yes Figure 2 Top view.

[0046] Figure 4 yes Figure 2 The main view.

[0047] Figure 5 yes Figure 1 A schematic diagram of the vibration pickup structure.

[0048] Figure 6 yes Figure 5 The main view.

[0049] Figure 7 yes Figure 5 A schematic diagram of the structure of the central base.

[0050] Figure 8 yes Figure 5 A schematic diagram of a medium-flexible hinge.

[0051] Figure 9 This is a schematic diagram of the time domain result of the vibration signal of a fiber optic accelerometer in Example 7 before preprocessing.

[0052] Figure 10 This is a schematic diagram of the time domain result of the vibration signal preprocessing of a fiber optic accelerometer in Example 7.

[0053] Figure 11 This is a schematic diagram of the frequency domain result of the vibration signal of a fiber optic accelerometer in Example 7 before preprocessing.

[0054] Figure 12 This is a schematic diagram of the frequency domain result of the vibration signal preprocessing of a fiber optic accelerometer in Example 7.

[0055] Figure 13 This is the spectrum of a fiber optic accelerometer sensor in Example 8 at a certain measurement point during time period 1.

[0056] Figure 14 This is the spectrum diagram of a fiber optic accelerometer sensor in Example 8 at a certain measurement point during time period 2.

[0057] Figure 15 This is the spectrum of a fiber optic accelerometer sensor in Example 8 at a certain measurement point during time period 3.

[0058] Figure 16 This is the spectrum of a fiber optic accelerometer sensor in Example 8 at a certain measurement point during time period 4.

[0059] Figure 17 This is a graph showing the peak-to-peak displacement changes of a fiber optic accelerometer sensor in Example 9 during two time periods on July 5th.

[0060] Figure 18 This is a graph showing the peak-to-peak displacement changes of another fiber optic accelerometer sensor in Example 9 during two time periods on July 5th.

[0061] In the diagram: Signal sensing unit 1, fiber optic accelerometer 11, sensor 111, sensor 112, sensor 113, sensor 114, sensor 115, sensor 116, sensor 111, sensor 121, sensor 122, sensor 123, sensor 124, sensor 125, sensor 126, demodulation unit 2, signal processing unit. 3. Stator end of turbine unit 4. Vibration pickup structure 5. Base 51. First L-shaped beam 52. First beam groove 521. Mass block 53. Mass groove 531. Flexible hinge 54. Elastic part 541. Concave structure 542. Optical fiber 55. First fiber grating 551. Second fiber grating 552. Second L-shaped beam 56. Second beam groove 561. Shell 57. First channel 6. Second channel 61. Third channel 62. Fourth channel 63. Epoxy resin adhesive 7. Insulating glass ribbon 71. Detailed Implementation

[0062] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0063] Please see Figure 1 — Figure 18 A vibration displacement monitoring device for the stator end of a hydro turbine unit that is resistant to electromagnetic interference, the device comprising a signal sensing unit 1, a demodulation unit 2 and a signal processing unit 3;

[0064] The signal sensing unit 1 includes multiple fiber optic accelerometers 11, which are spaced apart on the side wall of the stator end 4 of the turbine unit.

[0065] The outputs of multiple fiber Bragg grating accelerometers 11 are all connected to the input signal of demodulation unit 2, and the output of demodulation unit 2 is connected to the input signal of signal processing unit 3.

[0066] The fiber optic accelerometer 11 includes a housing 57 and a vibration pickup structure 5. The vibration pickup structure 5 is located inside the housing 57, and one side of the housing 57 is connected to one end of the stator end 4 of the turbine unit.

[0067] The vibration pickup structure 5 includes a base 51, a first L-shaped beam 52, and a mass block 53;

[0068] The middle part of the base 51 is connected to the bottom of the flexible hinge 54, the top of the flexible hinge 54 is connected to the bottom of the mass block 53, the top of the mass block 53 is provided with a mass groove 531, and the bottom of the mass groove 531 is connected to the middle of the optical fiber 55.

[0069] One side of the base 51 is connected to the bottom of the first L-shaped beam 52. The top of the first L-shaped beam 52 is provided with a first beam groove 521. The height of the first beam groove 521 is the same as the height of the mass groove 531. The first beam groove 521 is connected to one end of the optical fiber 55.

[0070] The optical fiber 55 is provided with a first fiber grating 551 at the position between the mass groove 531 and the first beam groove 521.

[0071] The flexible hinge 54 has an elastic part 541 in the middle, and both sides of the elastic part 541 are concave structures 542. The concave structure 542 is an arc-shaped structure that is recessed towards the center line of the elastic part 541. The width of the middle part of the elastic part 541 is smaller than the width of the top part of the elastic part 541, and the width of the middle part of the elastic part 541 is smaller than the width of the bottom part of the elastic part 541.

[0072] The vibration pickup structure 5 includes a second L-shaped beam 56, the bottom of which is connected to the other side of the base 51, and the second L-shaped beam 56 and the first L-shaped beam 52 are symmetrically distributed along the base 51.

[0073] The top of the second L-shaped beam 56 is provided with a second beam groove 561, the second beam groove 561 is at the same height as the first beam groove 521, and the second beam groove 561 is connected to the other end of the optical fiber 55.

[0074] A second fiber grating 552 is provided on the optical fiber 55 located between the mass groove 531 and the second beam groove 561.

[0075] The fiber optic accelerometer 11 includes sensor 111, sensor 112, sensor 113, sensor 114, sensor 115, sensor 116, sensor 111, sensor 122, sensor 123, sensor 124, sensor 125, and sensor 126.

[0076] Sensors 111, 112, 113, 114, 115, and 116 are distributed at intervals on the top side wall of the stator end 4 of the turbine unit.

[0077] Sensors 121 (number 21), 122 (number 22), 123 (number 23), 124 (number 24), 125 (number 25), and 126 (number 26) are distributed at intervals on the bottom side wall of the stator end 4 of the turbine unit.

[0078] Sensors 111, 112, and 113 are connected to the input of the first channel 6, and the output of the first channel 6 is connected to the input of the demodulation unit 2.

[0079] Sensors 114, 115, and 116 are connected to the input of the second channel 61, and the output of the second channel 61 is connected to the input of the demodulation unit 2.

[0080] The twenty-first sensor 121, the twenty-second sensor 122, and the twenty-third sensor 123 are connected to the input signal of the third channel 62, and the output signal of the third channel 62 is connected to the input signal of the demodulation unit 2.

[0081] Sensors 124, 125, and 126 are connected to the input of the fourth channel 63, and the output of the fourth channel 63 is connected to the input of the demodulation unit 2.

[0082] An epoxy resin adhesive 7 is provided between the bottom of the fiber optic accelerometer 11 and the side wall of the stator end 4 of the turbine unit.

[0083] The top of the fiber optic accelerometer 11 is connected to the middle of the insulating glass ribbon 71, and the two ends of the insulating glass ribbon 71 are connected to the side of the stator end 4 of the turbine unit.

[0084] The supplementary description of this utility model is as follows:

[0085] The demodulation unit 2 mentioned in this utility model refers to a fiber optic grating demodulator.

[0086] The signal processing unit 3 described in this utility model refers to a computer, which has the function of calculating demodulated signals.

[0087] Example 1:

[0088] Please see Figure 1 — Figure 18A vibration displacement monitoring device for the stator end of a hydro-turbine unit that resists electromagnetic interference is disclosed. The device includes a signal sensing unit 1, a demodulation unit 2, and a signal processing unit 3. The signal sensing unit 1 includes multiple fiber optic accelerometers 11, which are spaced apart on the sidewall of the stator end 4 of the hydro-turbine unit. The output terminals of the multiple fiber optic accelerometers 11 are all connected to the input terminal of the demodulation unit 2, and the output terminal of the demodulation unit 2 is connected to the input terminal of the signal processing unit 3.

[0089] In application, multiple fiber optic accelerometers 11 are first fixed to the side of the stator end 4 of the turbine unit. The fixed position of the fiber optic accelerometer 11 is the measuring point. When the turbine is working, the multiple fiber optic accelerometers 11 simultaneously measure the vibration signal of the measuring point, and then obtain multiple vibration optical signals. The demodulation unit 2 then demodulates the multiple vibration optical signals to obtain demodulated signals. Then, the signal processing unit calculates based on the demodulated signals to obtain the frequency and displacement value of the vibration signal of the multiple measuring points. Finally, the vibration condition of the stator end 4 of the turbine unit is judged based on the frequency and displacement value of the vibration signal.

[0090] Example 2:

[0091] The basic content is the same as in Example 1, except that:

[0092] Please see Figure 1 — Figure 8 The fiber Bragg grating accelerometer 11 includes a housing 57 and a vibration pickup structure 5. The vibration pickup structure 5 is located inside the housing 57, and one side of the housing 57 is connected to one end of the stator end 4 of the turbine unit. The vibration pickup structure 5 includes a base 51, a first L-shaped beam 52, and a mass block 53. The middle part of the base 51 is connected to the bottom of a flexible hinge 54, and the top of the flexible hinge 54 is connected to the bottom of the mass block 53. A mass groove 531 is provided on the top of the mass block 53, and the bottom of the mass groove 531 is connected to the middle part of an optical fiber 55. One side of the base 51 is connected to the bottom of the first L-shaped beam 52, and a first beam groove 521 is provided on the top of the first L-shaped beam 52. The height of the first beam groove 521 is the same as the height of the mass groove 531, and the first beam groove 521 is connected to one end of the optical fiber 55. A first fiber Bragg grating 551 is provided on the portion of the optical fiber 55 located between the mass groove 531 and the first beam groove 521. The flexible hinge 54 has an elastic part 541 in the middle, and both sides of the elastic part 541 are concave structures 542. The concave structure 542 is an arc-shaped structure that is recessed towards the center line of the elastic part 541. The width of the middle part of the elastic part 541 is smaller than the width of the top part of the elastic part 541, and the width of the middle part of the elastic part 541 is smaller than the width of the bottom part of the elastic part 541.

[0093] In application, when the measuring point at the stator end 4 of the turbine unit vibrates, the first L-shaped beam 52 vibrates along with the measuring point. The mass block 53 and the flexible hinge 54, under their own inertia, will generate relative displacement with respect to the measuring point. Therefore, the first fiber optic grating 551 located between the first beam groove 521 and the mass groove 531 is stretched and compressed, causing axial strain in the first fiber optic grating 551, resulting in a shift in its center wavelength. Thus, a vibration optical signal is obtained based on the vibration signal from the measuring point. A linear relationship can be established between the vibration acceleration in the vibration signal and the center wavelength shift in the vibration optical signal. Subsequently, the vibration acceleration of the vibration signal can be obtained from the center wavelength shift of the vibration optical signal. The flexible hinge 54 is the elastic element of the fiber optic grating accelerometer 11. Due to the concave structures 542 on both sides of the middle section, its width is the smallest. Therefore, it is easy to generate elastic deformation. The flexible hinge 54 has the advantages of frictionless, wear-free and high sensitivity during measurement. The flexible hinge 54 adopts an integrated structure design, that is, it is processed by integrated cutting, which is not only easy to process, but also can effectively reduce the measurement error caused by component assembly. Compared with the traditional cantilever beam fiber grating accelerometer, the flexible hinge 54 has a higher natural frequency, which can increase the frequency measurement range of the fiber grating accelerometer 11. The flexible hinge 54 also adopts an arc-shaped package, which makes the fiber grating accelerometer 11 more miniaturized. At the same time, the first fiber grating 551 is a bending resistant fiber grating, which solves the problem of light loss in the arc-shaped package. The vibration pickup structure 5 is made of non-magnetic material, which can ensure that the fiber grating accelerometer 11 will not affect the normal operation of the turbine in the electromagnetic environment.

[0094] Example 3:

[0095] The basic content is the same as in Example 1, except that:

[0096] Please see Figure 1 — Figure 8 The vibration pickup structure 5 includes a second L-shaped beam 56, the bottom of which is connected to the other side of the base 51. The second L-shaped beam 56 and the first L-shaped beam 52 are symmetrically distributed along the base 51. A second beam groove 561 is provided on the top of the second L-shaped beam 56. The second beam groove 561 is at the same height as the first beam groove 521. The second beam groove 561 is connected to the other end of the optical fiber 55. A second fiber grating 552 is provided on the part of the optical fiber 55 located between the mass groove 531 and the second beam groove 561.

[0097] In application, the second L-shaped beam 56 and the first L-shaped beam 52 are symmetrically distributed along the base 51. Therefore, when the stator end 4 of the turbine unit vibrates, the second fiber grating 552 and the first fiber grating 551 generate strains in opposite directions and of the same magnitude. Through the disclosed demodulation method, temperature compensation can be achieved while improving the measurement sensitivity of the fiber grating accelerometer 11. Both the second fiber grating 552 and the first fiber grating 551 are suspended and fixed, which can effectively avoid the chirping effect. Furthermore, the suspended and fixed second fiber grating 552 and the first fiber grating 551 are far from the central layer of the flexible hinge 54, thus amplifying the strain of the second fiber grating 552 and the first fiber grating 551.

[0098] Example 4:

[0099] The basic content is the same as in Example 1, except that:

[0100] Please see Figure 1 — Figure 4 The fiber optic accelerometer 11 includes sensor 111, sensor 112, sensor 113, sensor 114, sensor 115, sensor 116, sensor 121, sensor 122, sensor 123, sensor 124, sensor 125, and sensor 126. Sensors 111, 112, 113, 114, 115, and 116 are spaced apart on the top sidewall of the stator end 4 of the turbine unit; sensors 121, 122, 123, 124, 125, and 126 are spaced apart on the bottom sidewall of the stator end 4 of the turbine unit.

[0101] In application, due to the large number of parallel branches in the stator winding of the turbine, if the number of fiber optic grating accelerometers 11 is small, the number of vibration optical signals measured will be small, making it impossible to effectively and comprehensively monitor the stator end 4 of the turbine unit. This will bring many uncertainties to the maintenance plan. Therefore, sensors 111, 112, 113, 114, 115, and 116 are distributed at 60-degree intervals on the top side wall of the stator end 4 of the turbine unit, and sensors 121, 122, 123, 124, 125, and 126 are distributed at 60-degree intervals on the bottom side wall of the stator end 4 of the turbine unit. This will achieve the effect of comprehensively capturing the vibration signals of the stator end 4 of the turbine unit.

[0102] Example 5:

[0103] The basic content is the same as in Example 1, except that:

[0104] Please see Figure 1 — Figure 4 Sensors 111, 112, and 113 are connected to the input of the first channel 6, and the output of the first channel 6 is connected to the input of the demodulation unit 2. Sensors 114, 115, and 116 are connected to the input of the second channel 61, and the output of the second channel 61 is connected to the input of the demodulation unit 2. Sensors 121, 122, and 123 are connected to the input of the third channel 62, and the output of the third channel 62 is connected to the input of the demodulation unit 2. Sensors 124, 125, and 126 are connected to the input of the fourth channel 63, and the output of the fourth channel 63 is connected to the input of the demodulation unit 2.

[0105] In application, wavelength division multiplexing (WDM) is used to transmit the vibration optical signal. Sensors 111, 112, and 113 are all connected to a 1-to-4 fiber optic splitter, and then the vibration optical signal is transmitted to demodulation unit 2 through the first channel 6. Sensors 114, 115, and 116 are all connected to a 1-to-4 fiber optic splitter, and then the vibration optical signal is transmitted to demodulation unit 2 through the second channel 61. Sensors 121, 122, and 123 are all connected to a 1-to-4 fiber optic splitter, and then the vibration optical signal is transmitted to demodulation unit 2 through the third channel 62. Sensors 124 and 125... Sensor 126 (number 26) is connected to a 1-to-4 fiber optic splitter, and the vibration light signal is transmitted to demodulation unit 2 through the fourth channel 63. Sensors 111 (number 111), 112 (number 112), 113 (number 113), 114 (number 114), 115 (number 115), 116 (number 116), 121 (number 121), 122 (number 122), 123 (number 123), 124 (number 124), 125 (number 125), and 126 (number 126) are connected to the 1-to-4 fiber optic splitter using ordinary single-mode fiber optic cable. The first channel 6, the second channel 61, the third channel 62, and the fourth channel 63 are ordinary single-mode fiber optic cable. The demodulation unit 2 is connected to the signal processing unit via a network cable.

[0106] Example 6:

[0107] The basic content is the same as in Example 1, except that:

[0108] Please see Figure 1 — Figure 8 An epoxy resin adhesive 7 is provided between the bottom of the fiber optic accelerometer 11 and the sidewall of the turbine stator end 4. The top of the fiber optic accelerometer 11 is connected to the middle of the insulating glass ribbon 71, and both ends of the insulating glass ribbon 71 are connected to the sidewall of the turbine stator end 4. Preferably, the material of the housing 57 is epoxy resin.

[0109] In application, to prevent the fiber optic accelerometer 11 from falling off during vibration at the stator end 4 of the turbine unit, epoxy resin adhesive 7 is used to firmly attach the bottom of the fiber optic accelerometer 11 to the stator end 4 of the turbine unit. Insulating glass ribbon can also be used for secondary binding and fixing of the fiber optic accelerometer 11. The internal electrical environment of the generator is very harsh, a special environment with high voltage and strong alternating electromagnetic field. The housing 57 is made of epoxy resin material, which has corrosion resistance, high temperature resistance, wear resistance and good insulation, so as to avoid affecting the safe operation of the generator. The epoxy resin adhesive and insulating glass ribbon used for fixing are also insulating materials.

[0110] Example 7:

[0111] The basic content is the same as in Example 1, except that:

[0112] Please see Figure 9 — Figure 12 During the demodulation of the vibration optical signal by demodulation unit 2 and its transmission to signal processing unit 3, DC signals inevitably get mixed in. These DC signals can overwhelm low-frequency signals, causing distortion in the demodulated signal. Therefore, a mean-removal method can be used to preprocess the demodulated signal to remove the DC component and reduce errors. The vibration acceleration of a fiber optic accelerometer 11 within a 0.5-second time range is arbitrarily selected for the aforementioned preprocessing. The time and frequency domain comparisons before and after preprocessing are as follows: Figure 9 — Figure 12 As shown in the figure, the comparison shows that the acceleration signal after the above preprocessing is smoother and the amplitude is more stable. Moreover, all high-frequency noise above 100Hz is filtered out, but the energy of frequencies below 100Hz is not lost, and the useful signal is retained.

[0113] Example 8:

[0114] The basic content is the same as in Example 7, except that:

[0115] Please see Figure 13 — Figure 16By arbitrarily selecting vibration signals from a fiber optic accelerometer at different time periods (1, 2, 3, and 4) at a certain measurement point, and analyzing them, the following results are obtained: Figure 13 — Figure 16 As shown in the spectrum diagrams, the four spectrum diagrams mainly include two types of vibrations: a 6Hz vibration and a 100Hz vibration. The 6Hz vibration is the main vibration, which is three times the rotational frequency and belongs to the typical rotational frequency vibration. It can be used for routine monitoring of the stator end 4 of the turbine unit. The 100Hz vibration belongs to the typical extreme frequency vibration and requires more attention.

[0116] Example 9:

[0117] The basic content is the same as in Example 8, except that:

[0118] Please see Figure 17 — Figure 18 The displacement peak-to-peak values ​​of two randomly selected fiber optic accelerometers 11 at different measuring points were analyzed at different time intervals, and their changes were as follows: Figure 17 — Figure 18 As shown, the peak-to-peak values ​​of the vibration displacement of the two fiber optic accelerometers 11 at different time periods all fluctuate stably around a certain value, with a fluctuation range not exceeding 30 μm, which meets the vibration fluctuation range of the stator end during normal operation of the hydro-generator unit.

[0119] The above description is only a preferred embodiment of the present utility model. The protection scope of the present utility model is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present utility model should be included in the protection scope recorded in the claims.

Claims

1. A device for monitoring the vibration displacement at the stator end of a hydro-turbine unit that is resistant to electromagnetic interference, characterized in that: The device includes a signal sensing unit (1), a demodulation unit (2), and a signal processing unit (3). The signal sensing unit (1) includes multiple fiber optic accelerometers (11), which are spaced apart on the side wall of the stator end (4) of the turbine unit. The outputs of multiple fiber optic accelerometers (11) are all connected to the input signal of the demodulation unit (2), and the output of the demodulation unit (2) is connected to the input signal of the signal processing unit (3). The fiber optic accelerometer (11) includes a housing (57) and a vibration pickup structure (5). The vibration pickup structure (5) is located inside the housing (57). One side of the housing (57) is connected to one end of the stator end (4) of the turbine unit.

2. The anti-electromagnetic interference stator end vibration displacement monitoring device for a hydro-turbine unit according to claim 1, characterized in that: The vibration pickup structure (5) includes a base (51), a first L-shaped beam (52), and a mass block (53); The middle part of the base (51) is connected to the bottom of the flexible hinge (54), the top of the flexible hinge (54) is connected to the bottom of the mass block (53), the top of the mass block (53) is provided with a mass groove (531), and the bottom of the mass groove (531) is connected to the middle of the optical fiber (55). One side of the base (51) is connected to the bottom of the first L-shaped beam (52), and the top of the first L-shaped beam (52) is provided with a first beam groove (521). The height of the first beam groove (521) is the same as the height of the mass groove (531), and the first beam groove (521) is connected to one end of the optical fiber (55). The optical fiber (55) is provided with a first fiber grating (551) at the position between the mass groove (531) and the first beam groove (521).

3. The anti-electromagnetic interference stator end vibration displacement monitoring device for a hydro-turbine unit according to claim 2, characterized in that: The flexible hinge (54) has an elastic part (541) in the middle, and both sides of the elastic part (541) are concave structures (542). The concave structure (542) is an arc-shaped structure that is recessed towards the center line of the elastic part (541). The width of the middle part of the elastic part (541) is smaller than the width of the top of the elastic part (541), and the width of the middle part of the elastic part (541) is smaller than the width of the bottom of the elastic part (541).

4. The anti-electromagnetic interference stator end vibration displacement monitoring device for a hydro-turbine unit according to claim 3, characterized in that: The vibration pickup structure (5) includes a second L-shaped beam (56), the bottom of which is connected to the other side of the base (51), and the second L-shaped beam (56) and the first L-shaped beam (52) are symmetrically distributed along the base (51); The top of the second L-shaped beam (56) is provided with a second beam groove (561), the second beam groove (561) is at the same height as the first beam groove (521), and the second beam groove (561) is connected to the other end of the optical fiber (55). The optical fiber (55) is provided with a second fiber grating (552) at the part between the mass groove (531) and the second beam groove (561).

5. The anti-electromagnetic interference stator end vibration displacement monitoring device for a hydro-turbine unit according to claim 1, characterized in that: The fiber optic accelerometer (11) includes sensor 11 (111), sensor 12 (112), sensor 13 (113), sensor 14 (114), sensor 15 (115), sensor 16 (116), sensor 21 (121), sensor 22 (122), sensor 23 (123), sensor 24 (124), sensor 25 (125), and sensor 26 (126).

6. The anti-electromagnetic interference stator end vibration displacement monitoring device for a hydro-turbine unit according to claim 5, characterized in that: The eleventh sensor (111), the twelfth sensor (112), the thirteenth sensor (113), the fourteenth sensor (114), the fifteenth sensor (115), and the sixteenth sensor (116) are distributed at intervals on the top side wall of the stator end (4) of the turbine unit; The twenty-first sensor (121), twenty-second sensor (122), twenty-third sensor (123), twenty-fourth sensor (124), twenty-fifth sensor (125), and twenty-sixth sensor (126) are distributed at intervals on the bottom side wall of the stator end (4) of the turbine unit.

7. The anti-electromagnetic interference stator end vibration displacement monitoring device for a hydro-turbine unit according to claim 6, characterized in that: The eleventh sensor (111), the twelfth sensor (112), and the thirteenth sensor (113) are connected to the input of the first channel (6), and the output of the first channel (6) is connected to the input of the demodulation unit (2). The fourteenth sensor (114), the fifteenth sensor (115), and the sixteenth sensor (116) are connected to the input of the second channel (61), and the output of the second channel (61) is connected to the input of the demodulation unit (2). The twenty-first sensor (121), twenty-second sensor (122), and twenty-third sensor (123) are connected to the input signal of the third channel (62), and the output of the third channel (62) is connected to the input signal of the demodulation unit (2). The twenty-fourth sensor (124), the twenty-fifth sensor (125), and the twenty-sixth sensor (126) are connected to the input signal of the fourth channel (63), and the output of the fourth channel (63) is connected to the input signal of the demodulation unit (2).

8. The anti-electromagnetic interference stator end vibration displacement monitoring device for a hydro-turbine unit according to claim 1, characterized in that: An epoxy resin adhesive (7) is provided between the bottom of the fiber optic accelerometer (11) and the side wall of the stator end (4) of the turbine unit.

9. The anti-electromagnetic interference stator end vibration displacement monitoring device for a hydro-turbine unit according to claim 8, characterized in that: The top of the fiber optic accelerometer (11) is connected to the middle of the insulating glass ribbon (71), and the two ends of the insulating glass ribbon (71) are connected to the side of the turbine stator end (4).

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