A non-contact monitoring system and method for vibration of an end portion of a generator stator

Abstract

The application discloses a kind of generator stator end vibration non-contact monitoring system and method, system includes light beam excitation unit, light signal joint unit, contrast unit, measurement unit, control acquisition unit, data analysis unit and spectral analysis unit;Light signal joint unit is connected with light beam excitation unit, the laser generated is separated into reference light and probe light;Light signal joint unit inputs reference light into contrast unit, obtains first reflected light, inputs probe light into measurement unit, obtains second reflected light;Contrast unit and measurement unit are reflected back light signal joint unit with first reflected light and second reflected light, obtain interference light;Control acquisition unit is connected with light signal joint unit by spectral analysis unit, receives interference light, obtains the output of digital signal;Control acquisition unit transmits digital signal to data analysis unit, obtains end vibration spectrum.The application realizes that sensor and probe object non-contact vibration monitoring, improves measurement accuracy.

Description

Technical Field

[0001] This invention relates to the field of generator stator core monitoring technology, and in particular to a non-contact monitoring system and method for generator stator end vibration. Background Technology

[0002] Vibration is one of the most important factors causing machine damage, especially in motors. First, vibration causes relative movement between adjacent parts, which may cause friction and lead to wear; second, stress deformation may cause high cyclic fatigue, tensile stress and / or shear stress in materials, causing adhesive or coating materials to loosen.

[0003] In hydroelectric generators, horizontal vibration of the stator frame causes significant damage. This is primarily manifested in the accelerated wear of components such as the core and conductor bars after prolonged high-intensity vibration, reducing their service life. Structural components are affected by alternating stress, leading to a decrease in the rigidity of the stator frame and even fatigue fracture. In severe cases, deformation of the stator and rotor can cause collisions between rotating and stationary components, resulting in damage to the generator set. The causes of horizontal vibration in the stator frame are varied, and different characteristics and intensities of vibration produce different levels of damage to different types of equipment. The main causes of stator frame vibration include: firstly, the electromagnetic force from the rotor's out-of-roundness cutting the magnetic field directly acts on the stator and core, transmitting to the stator frame and generating self-excited vibration; secondly, insufficient stator rigidity leads to significant deformation under external forces; and finally, other mechanical friction also contributes to vibration.

[0004] In steam turbine generators, the stator winding ends are subjected to alternating electromagnetic forces during normal operation and enormous transient electromagnetic forces during outlet or internal short circuits. As the single-unit capacity of the generator increases, the electromagnetic and mechanical forces on the stator winding ends also increase. Because the frequency of the electromagnetic vibration force on the ends is twice the grid frequency, with fewer tangential and axial components and predominantly radial, forming a near-elliptical shape, resonance will occur when the natural frequency of the end winding approaches twice the power frequency (100Hz), especially when the end winding's vibration shape is elliptical. If the generator stator winding slot fixing, end support, binding, and manufacturing processes do not meet requirements, even a small excitation force can induce significant vibration. Prolonged resonance can lead to increased vibration amplitude during operation, causing loosening, wear, and insulation damage to the end windings and structural components, ultimately resulting in accidents.

[0005] Long-term operational practice and maintenance experience show that the internal vibration state of a generator is not static. Under the influence of alternating electromagnetic forces and thermal stress, insulation shrinkage, wear, and local loosening of fasteners cause changes in modal parameters. A steam turbine generator that is fully qualified at commissioning may, after long-term operation, have its natural frequency fall within the harmonic resonance range of the electromagnetic force, resulting in a deterioration of the vibration state. General electrical monitoring and external component vibration monitoring cannot reflect this dangerous vibration change, making it difficult to completely avoid sudden accidents. Therefore, from the perspective of long-term safe operation, it is essential to directly monitor the vibration amplitude at the stator winding ends during routine maintenance. Furthermore, maintenance experience has shown that if the dynamic characteristics at the ends of a steam turbine generator are unqualified during maintenance, exhibiting elliptical vibration modes near the harmonic frequency, it is difficult to change the overall dynamic characteristics of the ends by simply modifying the end structure locally. Remaking the stator windings and end fastening structures does not guarantee 100% success and incurs significant economic costs.

[0006] Taking all factors into consideration, the most economical and ideal solution to this problem is to install an online monitoring system to monitor the actual vibration changes at the stator winding ends in real time. Based on the intensity of the vibration of the stator winding end bars, the system can determine whether the turbine generator needs to be shut down for maintenance, thus enabling early fault alarms and effectively preventing sudden accidents.

[0007] Early monitoring primarily utilized the hammer impact method, but this could only be performed when the equipment was stopped. When the natural frequency of the equipment fell within the second harmonic electromagnetic oscillation range or the vibration amplitude exceeded the dangerous limit, it could not be detected in time. To address these issues of delayed detection of faults and potential hazards, current online monitoring of generator internal vibration mainly employs piezoelectric or fiber optic accelerometers, directly mounting the sensors on the surface of the object being measured. Piezoelectric vibration sensors are based on the piezoelectric effect and are a type of self-generating and electromechanical conversion sensor. Their sensitive element is made of piezoelectric material; when subjected to force, the surface of the piezoelectric material generates a charge. This charge is amplified by a charge amplifier, a measuring circuit, and impedance transformation, becoming an electrical output proportional to the applied force. However, the areas near the stator winding ends of steam turbines or the stator base of water turbines have high magnetic fields, high voltages, and high temperatures. This can induce high voltages of several kV or more within the coils of the vibration measurement components, endangering the safety of measurement personnel. Furthermore, working in this environment poses significant challenges to the stability of electronic components. Currently, there are also fiber optic sensors used to monitor the vibration at the ends of generator stator windings. These fiber optic sensors utilize the principle of light polarization, where a reflected beam passes through a birefringent plate to a light polarity analyzer and then returns to obtain the light interference pattern and the distance between vibration peaks. This means the entire device does not contain electronic components, thus eliminating the danger of induced high voltage. It also eliminates the need for insulation and shielding, and has strong anti-interference capabilities. However, this device is directly mounted on the surface of the object under test, and its installation, fixation, and encapsulation at critical locations in the generator pose certain risks. High-temperature environments also present significant challenges to the lifespan of optical components, and timely replacement is not convenient once the device fails. Summary of the Invention

[0008] To address the aforementioned issues, this invention provides a non-contact monitoring system and method for generator stator end vibration. The detection module is a non-metallic, non-electrified optical device that employs near-infrared laser coherent measurement, enabling non-contact vibration monitoring between the sensor and the detected object, thus avoiding the influence of ambient light on the measurement. Simultaneously, diffuse reflection light signals are collected, ensuring that a slight deviation of the incident angle from perpendicularity will not significantly affect the measurement accuracy. Furthermore, all vibration measurement points share most of the components of the entire system through time-division multiplexing.

[0009] This invention provides a non-contact monitoring system for generator stator end vibration, the specific technical solution of which is as follows:

[0010] The system includes a beam excitation unit, an optical signal integration unit, a comparison unit, a measurement unit, a control and acquisition unit, a data analysis unit, and a spectral analysis unit;

[0011] The beam excitation unit is connected to the optical signal combining unit, and the optical signal combining unit separates the laser generated by the beam excitation unit into a reference light and a probe light.

[0012] The optical signal combining unit is connected to both the reference unit and the measurement unit. The reference light is input into the reference unit to obtain the first reflected light; the probe light is input into the measurement unit to obtain the second reflected light.

[0013] The outputs of the comparison unit and the measurement unit are fed back to the optical signal joint unit, reflecting the first and second reflected light back to the optical signal joint unit to obtain interference light.

[0014] The control acquisition unit is connected to the optical signal combination unit through the spectral analysis unit, receives the interference light, and obtains the output of digital signals.

[0015] The control acquisition unit transmits the digital signal to the data analysis unit to obtain the end vibration spectrum.

[0016] Furthermore, the beam excitation unit is connected to the optical signal combining unit through an optical isolation component, and the laser generated by the beam excitation unit enters the optical signal combining unit after passing through the optical isolation component.

[0017] Furthermore, the comparison unit includes a comparison unit switch, an adjustable attenuator, an electrically controlled fiber optic delay line, a lens assembly, and a reflector;

[0018] The contrast unit switch is electrically connected to the optical signal combination unit via optical fiber; the contrast unit switch is electrically connected to the adjustable attenuator via optical fiber; the adjustable attenuator is electrically connected to the lens assembly via the electrically controlled optical fiber delay line.

[0019] Furthermore, the lens assembly is aligned with the center of the reflector and set at a preset distance apart.

[0020] Furthermore, the control acquisition unit is electrically connected to the electrically controlled fiber optic delay line and sends the delay amount to the electrically controlled fiber optic delay line.

[0021] Furthermore, the measurement unit includes a variable gain amplifier, a polarization controller, a measurement unit multiplexer, several lens assemblies, and corresponding objectives;

[0022] The variable gain amplifier and the optical signal unit are electrically connected via optical fiber; the variable gain amplifier and the polarization controller are electrically connected via optical fiber; the polarization controller and the measurement unit multiplexer are electrically connected via optical fiber; the measurement unit multiplexer and each of the lens assemblies are electrically connected via optical fiber pigtails; the center point of each lens assembly forms a 90° right angle with the center point of the corresponding objective lens and the detection point of the objective lens.

[0023] Furthermore, the control acquisition unit is electrically connected to the measurement unit multiplexer and sends a test point selection command to the measurement unit multiplexer.

[0024] Furthermore, the spectral analysis unit includes a dual-channel switch, a spectral measurement component, and a photodetector; the dual-channel switch is connected to the spectral measurement component and the photodetector respectively.

[0025] The present invention also provides a non-contact monitoring method for generator stator end vibration, the specific process of which is as follows:

[0026] S1: Set the delay of the electrically controlled fiber optic delay line to the preset value of the test point i;

[0027] S2: Set the variable gain amplifier value of the test point i through static calibration;

[0028] S3: Turn on the multiplexer of the measurement unit to the point i to be measured;

[0029] S4: Use the spectral analysis unit to obtain spectral data of the point to be measured;

[0030] S5: Process the spectral data of the test point through the data analysis unit and switch to the next test point until all test points are measured.

[0031] Furthermore, the static calibration process is as follows:

[0032] For the control unit, perform an electrically controlled fiber delay line scan to calibrate the zero optical path delay of each measurement channel;

[0033] Based on the zero optical path delay, an additional delay Δz is added. m This serves as the setting value for the measurement channel;

[0034] The optical power of the reference arm is obtained through the spectral analysis unit, and the optical switch of the reference arm is turned off.

[0035] Turn on the multiplexer of the measurement unit and select any point to be measured;

[0036] The variable gain amplifier is controlled by the acquisition unit to keep the optical power of the measurement unit consistent with that of the reference arm, and the setting value of the variable gain amplifier at this time is recorded.

[0037] The beneficial effects of this invention are as follows:

[0038] 1. This invention uses near-infrared laser measurement, with a set distance between the lens assembly and the point to be measured, to achieve non-contact measurement. This eliminates the safety risks of damage to the stator surface caused by contact measurement and the risk of major accidents caused by detachment. It also avoids the impact of high temperature, high pressure and strong magnetic field environment on the life of the sensor, making it easier to maintain and replace the sensor. At the same time, the measurement is not sensitive to external lighting and temperature, and can achieve measurement all year round. It also has high accuracy in measuring vibration frequency and amplitude.

[0039] 2. This invention uses time-division multiplexing for dynamic measurement. All measurement points can share all devices except the measurement unit, which facilitates system integration. At the same time, it can achieve optimized measurement of each channel and avoid the difference between the reflected light power and the reference light power caused by the change of the equivalent reflectivity of the surface of each test point, which would affect the contrast of the spectral interference fringes. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the system architecture of the present invention. Detailed Implementation

[0041] The technical solutions in the embodiments of the present invention are clearly and completely described in the following description. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0042] In the description of the embodiments of the present invention, it should be noted that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is conventionally placed during use, or the orientation or positional relationship in which those skilled in the art conventionally understand it during use. This is only for the convenience of describing the present invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention. Furthermore, the terms "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0043] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0044] Example 1

[0045] Embodiment 1 of the present invention discloses a non-contact monitoring system for generator stator end vibration, such as... Figure 1 As shown, the details are as follows:

[0046] The system includes a beam excitation unit, an optical signal integration unit, a comparison unit, a measurement unit, a control and acquisition unit, a data analysis unit, and a spectral analysis unit;

[0047] The beam excitation unit is connected to the optical signal combining unit, and the optical signal combining unit separates the laser generated by the beam excitation unit into a reference light and a probe light.

[0048] Specifically, the light distribution ratio of the optical signal joint unit is selected based on the reflectivity of the surface being detected on-site. The light output by the coupler becomes the reference light and the detection light in sequence, and is connected to the comparison unit and the measurement unit respectively.

[0049] In a preferred embodiment, the beam excitation unit is connected to the optical signal combination unit through an optical isolation component, and the laser generated by the beam excitation unit enters the optical signal combination unit after passing through the optical isolation component.

[0050] Specifically, the beam excitation unit is a swept beam excitation unit or a superradio diamagnetic tube broadband beam excitation unit, wherein the control circuit of the superradio diamagnetic laser consists of two parts: temperature control and current drive.

[0051] The laser output is delivered via a single-mode fiber with an FC / APC connector, and then connected to the port of the fiber optic isolator via a flange. After the laser outputs from the port, it is connected to the port of the optical signal combination unit via the flange.

[0052] The optical signal combining unit is connected to the reference unit and the measurement unit respectively. The reference light is input into the reference unit to obtain the first reflected light; the probe light is input into the measurement unit to obtain the second reflected light.

[0053] The outputs of the comparison unit and the measurement unit are fed back to the optical signal combination unit, reflecting the first and second reflected light back to the optical signal combination unit to obtain interference light.

[0054] In a preferred embodiment, the comparison unit includes a comparison unit switch, an adjustable attenuator, an electrically controlled fiber optic delay line, a lens assembly, and a reflector;

[0055] The contrast unit switch is electrically connected to the optical signal combination unit via optical fiber; the contrast unit switch is electrically connected to the adjustable attenuator via optical fiber; the adjustable attenuator is electrically connected to the lens assembly via the electrically controlled optical fiber delay line;

[0056] The lens assembly is aligned with the center of the reflector and is set at a preset distance apart.

[0057] The control and acquisition unit is electrically connected to the electrically controlled fiber optic delay line and sends the delay amount to the electrically controlled fiber optic delay line.

[0058] The control acquisition unit is also connected to the adjustable attenuator control to control the attenuation amount of the attenuator.

[0059] In a preferred embodiment, the measurement unit includes a variable gain amplifier, a polarization controller, a measurement unit multiplexer, several lens assemblies, and corresponding objective lenses;

[0060] The variable gain amplifier and the optical signal unit are electrically connected via optical fiber; the variable gain amplifier and the polarization controller are electrically connected via optical fiber; the polarization controller and the measurement unit multiplexer are electrically connected via optical fiber; the measurement unit multiplexer and each of the lens assemblies are electrically connected via optical fiber pigtails; the center point of each lens assembly forms a 90° right angle with the center point of the corresponding objective lens and the detection point of the objective lens.

[0061] Specifically, in order to increase the reflected power of reflected light on rough surfaces such as generator stators, highly reflective markers can be pasted at the test points or an appropriate amount of white reflective paint can be sprayed on them.

[0062] The control acquisition unit is electrically connected to the multiplexer of the measurement unit and sends a command to the multiplexer of the measurement unit to select the point to be measured.

[0063] In practice, due to the large size of the generator set, the spatial distance between each test point and the optical back-end components varies greatly. Furthermore, the effective adjustment range of the motorized fiber delay line on the reference arm is limited. Therefore, it is necessary to equip each test point with fiber optic pigtails of approximately the same length, using the required length of the fiber optic pigtail at the farthest test point as a benchmark. That is, the lengths of the multiple fiber optic pigtails are consistent, and each is based on the distance between the farthest test point and the multiplexer of the measurement unit.

[0064] In addition, the actual optical path of the reflected light in each channel is also affected by the optical path of the free space optical path between the lens assembly in the optical front-end assembly and the point to be measured. Therefore, the actual optical path difference of each channel can usually only be controlled to the millimeter level.

[0065] The length of the fiber optic pigtails at each test point is cut according to the standard of the pigtail length required at the furthest distance from the multi-channel optical switch, and the cutting accuracy only needs to be controlled at the millimeter level.

[0066] The control acquisition unit is connected to the optical signal combination unit through the spectral analysis unit, receives the interference light, and obtains the output of digital signals.

[0067] The control acquisition unit is also connected to the variable gain amplifier and the polarization controller to control the gain value of the variable gain optical amplifier and to perform polarization control on the polarization controller.

[0068] In a preferred embodiment, the spectral analysis unit includes a dual-channel switch, a spectral measurement component, and a photodetector; the dual-channel switch is connected to the spectral measurement component and the photodetector respectively.

[0069] Specifically, the dual-channel switch is used to select whether the instrument for spectral analysis is a spectral measurement component or a photodetector. The function of both the spectral measurement component and the photodetector is to acquire spectral data.

[0070] The control acquisition unit transmits the digital signal to the data analysis unit to obtain the end vibration spectrum.

[0071] Specifically, the data analysis unit is deployed in the host computer and can provide a clock signal for system synchronization.

[0072] The specific processing steps of digital signals by the data analysis unit are as follows:

[0073] Digital signals undergo Fourier transform through the data analysis unit, completing the conversion from the frequency domain to the spatial domain;

[0074] Based on the location of the center of the wave crest in the spatial domain, the location information of the detection point is obtained;

[0075] The location information of the detection point is collected over a period of time, and an inverse Fourier transform is performed to realize the transformation from the spatial domain to the frequency domain, thereby obtaining the vibration spectrum of the detection point and completing the monitoring of the detection point.

[0076] Specifically, the digital signal is uploaded to the host computer or enters the FPGA digital processing circuit in real time through a high-speed transmission bus. Then, the signal undergoes a Fourier transform to realize the conversion from the frequency domain to the spatial domain. Based on the center position of the wave peak in the spatial domain, the position information of the current detection point can be obtained in real time. The real-time data of the detection surface position over a period of time is then subjected to another Fourier transform to complete the transformation of the signal from the time domain to the frequency domain, thereby obtaining the vibration spectrum and the vibration amplitude at each frequency point. This completes the vibration monitoring of a detection point.

[0077] Based on the above system, when using it, the system is first started and initialized, and then the host computer sends various control commands to the control acquisition unit according to the set workflow.

[0078] Subsequently, the data analysis unit receives the spectral measurement data uploaded by the control acquisition unit, completes the DC filtering, wavelength-wavenumber conversion and Fourier transform data processing operations, and obtains the measurement results of the position of the test site changing over time.

[0079] Finally, the vibration information from all detection points is aggregated into a single data packet, which is then transmitted in real-time to the host unit in the control cabinet via an RS485 (or other bus) interface. This host unit interacts with the power plant's overall data management system. A database can also be built to store and manage massive amounts of historical data, and to perform comprehensive analysis of this data. This allows for not only quantitative monitoring of vibration at the stator end within the system but also the use of big data and artificial intelligence algorithms to correlate vibration status with the health status of other components within the generator.

[0080] In vibration monitoring of hydro-generators, it is generally necessary to monitor the vibration of the upper stator core ends and the lower stator core ends. For monitoring the lower stator core, the probe is installed on the lower frame. For monitoring the upper stator core, the probe is encapsulated in a ring-shaped mounting box, and the entire box is welded to the upper frame to increase stability and prevent the probe from slipping into the machine body. The number of screws and fasteners should be minimized, and necessary screws and bolts should be tightened by applying glue to prevent loosening.

[0081] Example 2

[0082] Embodiment 2 of the present invention discloses a non-contact monitoring method for generator stator end vibration based on Embodiment 1 above.

[0083] The signal-to-noise ratio of existing low-coherence optical vibration measurement methods decreases as the optical path difference between the reference arm and the measurement unit increases. To obtain the optimal signal-to-noise ratio for each channel, the actual zero optical path difference position of each channel can be statically calibrated by scanning the motorized fiber delay line on the reference arm and recorded in the database. During time-division multiplexing dynamic measurement, the fiber delay line is adjusted to the calibration position of the corresponding channel, thereby achieving optimized measurement of each channel.

[0084] The specific process is as follows:

[0085] S1: Set the delay of the electrically controlled fiber optic delay line to the preset value of the test point i;

[0086] S2: Set the variable gain amplifier value of the test point i through static calibration;

[0087] In a preferred embodiment, the static calibration process is as follows:

[0088] For the control unit, perform an electrically controlled fiber delay line scan to calibrate the zero optical path delay of each measurement channel;

[0089] Based on the zero optical path delay, an additional delay Δz is added. m This serves as the setting value for the measurement channel;

[0090] The optical power of the reference arm is obtained through the spectral analysis unit, and the optical switch of the reference arm is turned off.

[0091] Turn on the multiplexer of the measurement unit and select any point to be measured;

[0092] The variable gain amplifier is controlled by the acquisition unit to keep the optical power of the measurement unit consistent with that of the reference arm, and the setting value of the variable gain amplifier at this time is recorded.

[0093] S3: Turn on the multiplexer of the measurement unit to the point i to be measured;

[0094] S4: Use the spectral analysis unit to obtain spectral data of the point to be measured;

[0095] S5: Process the spectral data of the test point through the data analysis unit and switch to the next test point until all test points are measured.

[0096] Since the generator stator surface is relatively rough, and the vibration measurement principle of this method is based on the difference between the reflected optical path of the test point and the optical path of the reference arm, in order to avoid interference and ambiguity of the measured spectral signal due to the different reflected optical paths at various points on the rough surface, it is necessary to select a high-quality lens assembly at the optical front end, focus the sample arm beam on the test point surface as much as possible, and keep the spot size as small as possible, thereby improving the spatial resolution and reducing the impact of the different reflected optical paths at various points on the rough surface on the accuracy of the measurement signal and the axial resolution.

[0097] Based on the above method, the measurement process of any point is explained using single-point measurement as an example.

[0098] Taking the m-th measurement point as an example, under static conditions, its reflected optical path length from the optical signal joint unit is z. m,0 Under dynamic operating conditions, its maximum amplitude is set as A. m The normalized vibration waveform is δ m (t), at system time T m,0 At time 1, dynamic measurement of this channel begins. At this time, assume that the reference arm motorized fiber delay line has completed the delay adjustment according to the static calibration data, and the reflected optical path length of the reference arm from the optical signal joint unit is z. m,R =z m,0 +Δz m constant Δz m The optical path offset of the reference arm is set according to the actual situation, and is usually slightly larger than A. m Generally, all channels can be set to the same Δz. m .

[0099] At time t, the displacement A of the measured point relative to its static position. m δ(tT m,0 Therefore, the reflected optical path is z / 2.m (t)=z m,0 +(A m δ(tT m,0 ) / 2)*2=z m,0 +A m δ(tT m,0 ).

[0100] Assume the incident light field from the beam excitation unit arm onto the optical signal junction unit is E. in =E0S(k), where S(k) is the power spectral density function of the incident light. The reflected light from the optical signal co-unit enters the reference arm, and the transmitted light enters the sample arm. The ratio of reflected to transmitted power in the optical signal co-unit is R and T, respectively. Considering the transmission and fiber coupling losses on the sample arm and the reference arm, η is given. S,m ,η R The power reflectivity of the reference arm reflector and the test site in the m-th channel are Rm and Rm, respectively. S,m ,R R Then, the interference light field obtained by the reflected light from the m-th channel of the reference arm and the sample arm passing through the optical signal joint unit again is:

[0101]

[0102] Therefore, the intensity of the interference light is:

[0103]

[0104] Therefore, it can be seen that the reflected light intensity in the spectral domain (k-wavenumber domain) is affected by the reflected optical path difference A between the reference arm and the sample arm. m δ(tT m,0 )-Δz m Modulation.

[0105] When the sampling rate of the spectral measurement component is high enough, that is, much higher than the highest vibration frequency of the object under test, the reflected optical path difference at each moment can be extracted by Fourier transform. Furthermore, by analyzing the change of the reflected optical path difference over time, the vibration frequency and vibration amplitude of the point under test can be obtained.

[0106] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A non-contact monitoring system for generator stator end vibration, characterized in that, It includes a beam excitation unit, an optical signal combination unit, a comparison unit, a measurement unit, a control and acquisition unit, a data analysis unit, and a spectral analysis unit; The beam excitation unit is connected to the optical signal combining unit, and the optical signal combining unit separates the laser generated by the beam excitation unit into a reference light and a probe light. The optical signal combining unit is connected to both the reference unit and the measurement unit. The reference light is input into the reference unit to obtain the first reflected light; the probe light is input into the measurement unit to obtain the second reflected light. The outputs of the comparison unit and the measurement unit are fed back to the optical signal joint unit, reflecting the first and second reflected light back to the optical signal joint unit to obtain interference light. The comparison unit includes a comparison unit switch, an adjustable attenuator, an electrically controlled fiber optic delay line, a lens assembly, and a reflector; The contrast unit switch is electrically connected to the optical signal combination unit via optical fiber; the contrast unit switch is electrically connected to the adjustable attenuator via optical fiber; the adjustable attenuator is electrically connected to the lens assembly via the electrically controlled optical fiber delay line; The measurement unit includes a variable gain amplifier, a polarization controller, a measurement unit multiplexer, several lens assemblies, and corresponding objectives. The variable gain amplifier and the optical signal unit are electrically connected via optical fiber; the variable gain amplifier and the polarization controller are electrically connected via optical fiber; the polarization controller and the measurement unit multiplexer are electrically connected via optical fiber; the measurement unit multiplexer and each of the lens assemblies are electrically connected via optical fiber pigtails; the center point of each lens assembly forms a 90° right angle with the center point of the corresponding objective lens and the detection point of the objective lens; wherein, the delay of the electrically controlled fiber delay line is set to a preset value of the corresponding test point connected to the measurement unit multiplexer. The control acquisition unit is connected to the optical signal combination unit through the spectral analysis unit, receives the interference light, and obtains the output of digital signals. The control acquisition unit transmits the digital signal to the data analysis unit to obtain the end vibration spectrum.

2. The non-contact monitoring system for generator stator end vibration according to claim 1, characterized in that, The beam excitation unit is connected to the optical signal combining unit through an optical isolation component. The laser generated by the beam excitation unit enters the optical signal combining unit after passing through the optical isolation component.

3. The generator stator end vibration non-contact monitoring system according to claim 1, characterized in that, The lens assembly is aligned with the center of the reflector and is set at a preset distance apart.

4. The generator stator end vibration non-contact monitoring system according to claim 1, characterized in that, The control and acquisition unit is electrically connected to the electrically controlled fiber optic delay line and sends the delay amount to the electrically controlled fiber optic delay line.

5. The generator stator end vibration non-contact monitoring system according to claim 1, characterized in that, The control acquisition unit is electrically connected to the multiplexer of the measurement unit and sends a command to the multiplexer of the measurement unit to select the point to be measured.

6. The generator stator end vibration non-contact monitoring system according to claim 1, characterized in that, The spectral analysis unit includes a dual-channel switch, a spectral measurement component, and a photodetector; the dual-channel switch is connected to the spectral measurement component and the photodetector respectively.

7. A non-contact monitoring method for generator stator end vibration, based on the non-contact monitoring system for generator stator end vibration according to any one of claims 1-6, characterized in that, The methods include: S1: Set the delay of the electrically controlled fiber optic delay line to the preset value of the test point i; S2: Set the variable gain amplifier value of the test point i through static calibration; S3: Turn on the multiplexer of the measurement unit to the point i to be measured; S4: Use the spectral analysis unit to obtain spectral data of the point to be measured; S5: Process the spectral data of the test point through the data analysis unit and switch to the next test point until all test points are measured.

8. The non-contact monitoring method for generator stator end vibration according to claim 7, characterized in that, The static calibration process is as follows: For the control unit, perform an electrically controlled fiber delay line scan to calibrate the zero optical path delay of each measurement channel; Based on zero optical path delay, an additional delay is added. This serves as the setting value for the measurement channel; The optical power of the reference arm is obtained through the spectral analysis unit, and the optical switch of the reference arm is turned off. Turn on the multiplexer of the measurement unit and select any point to be measured; The variable gain amplifier is controlled by the acquisition unit to keep the optical power of the measurement unit consistent with that of the reference arm, and the setting value of the variable gain amplifier at this time is recorded.

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