Generator stator end vibration non-contact monitoring system and method

Abstract

The invention discloses a non-contact monitoring system and method for generator stator end vibration. The system comprises a light beam excitation unit, an optical signal combination unit, a contrast unit, a measurement unit, a control acquisition unit, a data analysis unit and a spectral analysis unit. The optical signal combination unit is connected with the light beam excitation unit and is used for separating the generated laser into reference light and detection light; the optical signal combination unit inputs the reference light into the contrast unit to obtain first reflected light, and inputs the probe light into the measurement unit to obtain second reflected light; the contrast unit and the measurement unit reflect the first reflected light and the second reflected light back to the light signal combination unit to obtain interference light; the control acquisition unit is connected with the optical signal combination unit through the spectrum analysis unit, receives interference light and obtains the output of a digital signal; and the control acquisition unit transmits the digital signal to the data analysis unit to obtain an end vibration spectrum. According to the invention, non-contact vibration monitoring of the sensor and the detected object is realized, and the measurement precision is improved.

Description

Technical Field

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

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

[0003] In a hydro-turbine generator, the horizontal vibration of the stator frame is extremely harmful. This is mainly manifested in that after long-term high-intensity vibration work, the iron core, wire rods and other components will be aggravated and wear will be reduced, and the service life will be reduced; the structural parts will be affected by alternating stress, causing the rigidity of the stator frame to decrease, and even fatigue fracture; in severe cases, the stator and rotor will deform, and the rotating and fixed parts will collide, causing damage to the generator set. There are many reasons for the horizontal vibration of the stator frame, and vibrations of different characteristics and intensities will cause different damages to different types of equipment. The main reasons for the vibration of the stator frame are as follows: first, the electromagnetic force of the rotor's out-of-roundness cutting magnetic field directly acts on the stator and the iron core, and is transmitted to the stator frame to produce self-excited vibration; second, the stator stiffness is insufficient, and the deformation is large due to external forces; finally, there are other mechanical frictions that produce vibrations.

[0004] In a steam turbine generator, the ends of the generator stator windings are subjected to alternating electromagnetic forces during normal operation and huge transient electromagnetic forces during outlet or internal short circuits. The increase in the capacity of a single generator will cause the ends of the generator stator windings to be subjected to increasingly greater electromagnetic and mechanical forces. Since the frequency of the electromagnetic vibration force on the ends is twice the frequency of the power grid, the tangential and axial components are relatively small, and the radial force is dominant, which is quasi-elliptical. Therefore, when the natural frequency of the end winding is close to twice the power frequency (100Hz), especially when the vibration shape of the end winding is elliptical, the winding will resonate. If the internal fixation, end support, binding fixation and process of the generator stator winding do not meet the requirements, even a small excitation force will induce greater vibration. If the generator is in a resonant state for a long time, the end windings and structural parts may become loose, worn, and the insulation damaged due to the increase in vibration amplitude during operation, which may cause accidents.

[0005] Long-term operation practice and maintenance experience show that the internal vibration state of the generator cannot remain unchanged. Under the action of alternating electromagnetic force and thermal stress, insulation shrinkage, wear, and local loosening of fasteners cause changes in modal parameters. After long-term operation, the natural frequency of a fully qualified steam turbine generator at the time of commissioning may fall within the range of the double-frequency electromagnetic force resonance, causing the vibration state to deteriorate. General electrical monitoring and external component vibration monitoring cannot reflect this dangerous vibration change, and it is difficult to completely avoid the occurrence of sudden accidents. Therefore, from the perspective of long-term safe operation, it is very necessary to directly monitor the vibration amplitude of the stator winding end during daily maintenance. In addition, maintenance experience has shown that if the dynamic characteristics of the end of a steam turbine generator are unqualified during maintenance, and there are elliptical vibration modes near the double frequency, it is difficult to change the overall dynamic characteristics of the end by simply changing the end structure. If the stator winding and the end fastening structure are remade, the transformation cannot guarantee 100% success, and the economic cost is very high.

[0006] After comprehensive consideration, the economical and ideal way to deal with this problem is to install an online monitoring system to monitor the actual vibration changes of the stator winding end in real time during operation, and decide whether the steam turbine generator needs to be shut down for maintenance based on the vibration intensity of the stator winding end bars, so as to realize the early fault alarm function and effectively prevent sudden accidents.

[0007] Early monitoring mainly used the hammering method, but it could only be performed when the equipment was stopped. It could not be discovered in time when the natural frequency fell into the double frequency electromagnetic oscillation range or the vibration amplitude exceeded the dangerous limit range during the operation of the equipment. In order to solve the above-mentioned problems of failure and hidden dangers that cannot be detected in time, the current online monitoring of the internal vibration of the generator mainly uses piezoelectric accelerometers or optical fiber accelerometers, and the sensors are directly installed on the surface of the object to be measured. Piezoelectric vibration sensor is a sensor based on the piezoelectric effect. It is a self-generating and electromechanical conversion sensor; its sensitive element is made of piezoelectric material. After the piezoelectric material is subjected to force, the surface generates a charge. This charge is amplified by the charge amplifier, the measurement circuit, and the impedance is transformed to become an electrical output proportional to the external force. However, the area near the end of the steam turbine stator winding or the stator base of the turbine has a high magnetic field, high voltage and high temperature environment, which can induce a high voltage of more than several KV in the coil of the vibration measurement component, endangering the safety of the measurement construction personnel, and working in this environment is full of challenges to the stability of electronic devices. At present, there are also fiber optic sensors used to monitor the vibration of the stator winding ends of generators. The fiber optic sensor uses the principle of light polarization to reflect the light beam through a birefringent plate to an optical polarity analyzer and then returns to obtain the light interference pattern and the distance between the vibration peaks. In this way, the entire device does not contain electronic devices, which solves the danger of induced high voltage, and does not require insulation and shielding, and has strong anti-interference ability. However, the device is directly installed on the surface of the object to be tested, and there are certain risks in installing, fixing and packaging it at a key position of the generator. The high temperature environment also poses a great challenge to the working life of the optical device. Once the device fails, it is not convenient to replace it in time. Summary of the invention

[0008] To solve the above problems, the present invention provides a system and method for non-contact monitoring of vibration at the stator end of a generator. The detection module is a non-metallic, non-electrical optical device, and adopts near-infrared laser coherent measurement to realize non-contact vibration monitoring between the sensor and the detection object, thereby avoiding the influence of environmental brightness on the measurement. At the same time, diffuse reflected light signals are collected to ensure that a slight deviation of the incident angle from vertical will not have a significant impact on the measurement accuracy. All vibration measurement points share most of the devices of the entire system through time division multiplexing.

[0009] The present invention provides a non-contact monitoring system for the vibration of a generator stator end, and the specific technical scheme is as follows:

[0010] The system includes a light beam excitation unit, a light signal combination unit, a control unit, a measurement unit, a control collection unit, a data analysis unit and a spectrum analysis unit;

[0011] The light beam excitation unit is connected to the light signal combining unit, and the light beam excitation unit separates the laser light generated by the light beam excitation unit into reference light and detection light through the light signal combining unit;

[0012] The optical signal combining unit is connected to the comparison unit and the measuring unit respectively, the reference light is input to the comparison unit to obtain the first reflected light; the detection light is input to the measuring unit to obtain the second reflected light;

[0013] The output feedback of the comparison unit and the measurement unit is connected to the optical signal combination unit, and the first reflected light and the second reflected light are reflected back to the optical signal combination unit to obtain interference light;

[0014] The control collection unit is connected to the optical signal combining unit through the spectrum analysis unit, receives the interference light, and obtains the output of the digital signal;

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

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

[0017] Further, the control unit includes a control unit switch, an adjustable attenuator, an electrically controlled optical fiber delay line, a lens assembly and a reflector;

[0018] The control unit switch is electrically connected to the optical signal combining unit through an optical fiber; the control unit switch is electrically connected to the adjustable attenuator through an optical fiber; and the adjustable attenuator is electrically connected to the lens assembly through the electrically controlled optical fiber delay line.

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

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

[0021] Further, the measuring unit includes a variable gain amplifier, a polarization controller, a measuring unit multiplexer, a plurality of lens assemblies and a corresponding objective lens;

[0022] The variable gain amplifier is electrically connected to the optical signal combining unit through optical fiber; the variable gain amplifier is electrically connected to the polarization controller through optical fiber; the polarization controller is electrically connected to the measurement unit multi-way switch through optical fiber; the measurement unit multi-way switch is electrically connected to each lens assembly through optical fiber pigtails; the center point of the lens assembly forms a 90° right angle with the corresponding center point of the objective lens and the detection point of the objective lens.

[0023] Furthermore, the control acquisition unit is electrically connected to the multi-way switch of the measurement unit, and sends a to-be-measured point selection instruction to the multi-way switch of the measurement unit.

[0024] Furthermore, the spectrum analysis unit includes a two-way switch, a spectrum measurement component and a photoelectric detector; the two-way switch is connected to the spectrum measurement component and the photoelectric detector respectively.

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

[0026] S1: setting the delay amount of the electrically controlled optical fiber delay line to a preset value of the point i to be measured;

[0027] S2: Setting the setting value of the variable gain amplifier at the point i to be measured by static calibration;

[0028] S3: Connect the multi-way switch of the measuring unit to the point i to be measured;

[0029] S4: using a spectrum analysis unit to obtain spectrum data of the point to be measured;

[0030] S5: The spectrum data of the point to be measured is processed by the data analysis unit, and the next point to be measured is switched to until all the points are measured.

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

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

[0033] Based on the zero optical path delay, add additional delay Δz m , as the setting value of the measurement channel;

[0034] Obtain the optical power of the reference arm through the spectrum analysis unit, and close the optical switch of the reference arm;

[0035] Turn on the multi-way switch of the measuring unit and select any point to be measured;

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

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

[0038] 1. The present invention adopts near-infrared laser measurement, and the lens assembly is separated from the point to be measured by a set distance, thereby realizing non-contact measurement, eliminating the safety risks of damage to the stator surface caused by contact measurement and major accidents caused by falling off, avoiding the influence of high temperature, high pressure and strong magnetic field environment on the life of the sensor, facilitating the maintenance and replacement of the sensor, and at the same time, the measurement is insensitive to external environmental lighting and temperature, and can realize measurement throughout the year and all day, and the measurement accuracy of vibration frequency and amplitude is high.

[0039] 2. The present invention adopts time-division multiplexing for dynamic measurement. All measuring points can share all devices except the measuring unit, which is convenient for system integration. At the same time, it can realize optimized measurement of each channel to avoid the difference between the reflected light power of each point and the reference light power caused by the change of the equivalent reflectivity of the surface of each point to be measured, thereby affecting the contrast of the spectral interference fringes. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of the system architecture of the present invention. DETAILED DESCRIPTION

[0041] The following description clearly and completely describes the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[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 invention product is usually placed when in use, or the orientation or positional relationship commonly understood by those skilled in the art, or the orientation or positional relationship in which the invention product is usually placed when in use, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first" and "second" are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0043] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] Example 1

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

[0046] The system includes a light beam excitation unit, a light signal combination unit, a control unit, a measurement unit, a control collection unit, a data analysis unit and a spectrum analysis unit;

[0047] The light beam excitation unit is connected to the light signal combining unit, and the laser light generated by the light beam excitation unit is separated into reference light and detection light through the light signal combining unit;

[0048] Specifically, the light distribution ratio of the optical signal combining unit selects the optimal value according to the reflective condition of the on-site detection surface, and the light output by the coupler becomes the reference light and the detection light in turn, which are connected to the control unit and the measurement unit respectively.

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

[0050] Specifically, the beam excitation unit is a frequency sweep beam excitation unit or a super radiant diode broadband beam excitation unit, wherein the control circuit of the super radiant diode laser is composed of two parts: temperature control and current drive;

[0051] The laser output is output by a single-mode optical fiber with an FC / APC head, and then connected to the port of the optical fiber isolator using a flange. After the laser is output from the port, it is connected to the port of the optical signal combining unit through the flange.

[0052] The optical signal combining unit is connected to the comparison unit and the measuring unit respectively, and the reference light is input to the comparison unit to obtain the first reflected light; the detection light is input to the measuring unit to obtain the second reflected light.

[0053] The output feedback of the comparison unit and the measurement unit is connected to the optical signal combining unit, and the first reflected light and the second reflected light are reflected back to the optical signal combining unit to obtain interference light.

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

[0055] The control unit switch is electrically connected to the optical signal combining unit through an optical fiber; the control unit switch is electrically connected to the adjustable attenuator through an optical fiber; the adjustable attenuator is electrically connected to the lens assembly through the electrically controlled optical fiber delay line;

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

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

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

[0059] As a preferred embodiment, the measuring unit includes a variable gain amplifier, a polarization controller, a measuring unit multiplexer, a plurality of lens assemblies and a corresponding objective lens;

[0060] The variable gain amplifier is electrically connected to the optical signal combining unit through optical fiber; the variable gain amplifier is electrically connected to the polarization controller through optical fiber; the polarization controller is electrically connected to the measurement unit multi-way switch through optical fiber; the measurement unit multi-way switch is electrically connected to each lens assembly through optical fiber pigtails; the center point of the lens assembly forms a 90° right angle with the corresponding center point of the objective lens and the detection point of the objective lens.

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

[0062] The control acquisition unit is electrically connected to the multi-way switch of the measurement unit, and sends a to-be-measured point selection instruction to the multi-way switch of the measurement unit.

[0063] In practice, due to the large size of the generator set, the spatial distance between each test point and the optical back-end component varies greatly, and the effective adjustment range of the electric optical fiber delay line on the reference arm is limited. Therefore, it is necessary to use the fiber pigtail length required by the farthest test point as a reference, and equip each test point with a fiber pigtail of substantially the same length. That is, the lengths of the multiple fiber pigtails are consistent, and are all based on the distance between the farthest test point and the multi-way switch of the measurement unit.

[0064] In addition, the actual optical path length of the reflected light of each channel is also affected by the optical path length of the free space optical path between the lens assembly in the optical front-end assembly and the position 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 optical fiber pigtail of each test point is cut according to the pigtail length required for the farthest distance from the multi-channel light switch, and the cutting accuracy only needs to be controlled in the millimeter level.

[0066] The control collection unit is connected to the optical signal combining unit through the spectrum analysis unit, receives the interference light, and obtains the output of the digital signal;

[0067] The control and collection 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 perform polarization control on the polarization controller.

[0068] As a preferred embodiment, the spectrum analysis unit includes a two-way switch, a spectrum measurement component and a photoelectric detector; the two-way switch is connected to the spectrum measurement component and the photoelectric detector respectively;

[0069] Specifically, the two-way switch is used to select the spectral analysis instrument as a spectral measurement component or a photoelectric detector, and the function of the spectral measurement component or the photoelectric detector is to obtain 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 process of the digital signal through the data analysis unit is as follows:

[0073] The digital signal is Fourier transformed through the data analysis unit to complete the conversion from frequency domain to spatial domain;

[0074] According to the center position of the wave crest in the spatial domain, the location information of the detection point is obtained;

[0075] The position information of the detection point within a period of time is collected and inverse Fourier transform is performed to realize the transformation from space domain to frequency domain, the vibration spectrum of the detection point is obtained, and the detection point monitoring is completed.

[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, and then the signal is Fourier transformed to achieve the conversion from frequency domain to space domain. The position information of the current detection point can be obtained in real time based on the center position of the spatial domain peak. The real-time data of the detection surface position within a period of time is Fourier transformed again to complete the signal transformation from time domain to frequency domain, so as to obtain the vibration spectrum and the vibration amplitude at each frequency point, thereby completing the vibration monitoring of a detection point.

[0077] Based on the above system, when in use, the system is first started and initialized, and the host computer sends various control instructions to the control acquisition unit according to the set workflow;

[0078] Afterwards, the data analysis unit receives the spectral measurement data uploaded by the control acquisition unit, completes DC filtering, wavelength-wavenumber conversion and Fourier transform data processing operations, and obtains the measurement result of the position of the measured point changing with time.

[0079] Finally, the vibration information of all detection points is integrated into a data packet, which is sent to the host in the floor cabinet in real time through the RS485 (or other bus) bus, and interacts with the entire data management system of the power plant through the host. A database can also be built to store and manage massive amounts of historical data, and conduct a comprehensive analysis of historical data, which can not only quantitatively monitor the vibration of the stator end inside the system, but also find the correlation between the vibration state and the health status of other components inside the entire generator through big data and artificial intelligence algorithms.

[0080] In the vibration monitoring of hydro-turbine generators, it is generally necessary to monitor the vibration conditions of the upper stator core end and the lower stator core end. The probe for monitoring the lower stator core is installed on the lower frame. For monitoring the upper stator core: the probe is encapsulated in an annular mounting box, and the entire box is welded to the upper frame to increase stability and prevent the probe from slipping into the body; minimize screw fasteners, and use glue to prevent loosening and tighten the necessary screws and bolts.

[0081] Example 2

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

[0083] The signal-to-noise ratio of the existing low-coherence optical vibrometer method will decrease with the increase of the optical path difference between the reference arm optical path and the measurement unit optical path. In order 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 electric fiber delay line on the reference arm and recorded in the database respectively. During the time-division multiplexing dynamic operation measurement process, 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: setting the delay amount of the electrically controlled optical fiber delay line to a preset value of the point i to be measured;

[0086] S2: Setting the setting value of the variable gain amplifier at the point i to be measured by static calibration;

[0087] As a preferred embodiment, the static calibration has the following specific process:

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

[0089] Based on the zero optical path delay, add additional delay Δz m , as the setting value of the measurement channel;

[0090] Obtain the optical power of the reference arm through the spectrum analysis unit, and close the optical switch of the reference arm;

[0091] Turn on the multi-way switch of the measuring unit and select any point to be measured;

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

[0093] S3: Connect the multi-way switch of the measuring unit to the point i to be measured;

[0094] S4: using a spectrum analysis unit to obtain spectrum data of the point to be measured;

[0095] S5: The spectrum data of the point to be measured is processed by the data analysis unit, and the next point to be measured is switched to until all the points are measured.

[0096] Since the surface of the generator stator is relatively rough, and the principle of vibration measurement in this method is based on the difference between the reflected optical path of the point to be measured and the optical path of the reference arm, in order to avoid the interference and blurring of the measured spectral signal caused by the different reflected optical path lengths at different points on the rough surface, it is necessary to use high-quality lens components on the optical front end to focus the sample arm light beam onto the surface of the point to be measured as much as possible, and keep the spot size as small as possible, so as to improve the spatial resolution and reduce the influence of the different reflected optical path lengths at different points on the rough surface on the measurement signal accuracy and axial resolution.

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

[0098] Taking the mth measurement point as an example, under static conditions, its reflected optical path from the optical signal combination unit is z m,0 , under dynamic operating conditions, its maximum amplitude is set to A m , the normalized vibration waveform is δ m (t), at system time T m,0 At this moment, the dynamic measurement of the channel begins. At this time, it is assumed that the reference arm electric optical fiber delay line has completed the delay adjustment according to the static calibration data, and the reflection optical path from the reference arm to the optical signal combination unit is z m,R =z m,0 +Δz m , constant Δz m A is the reference arm optical path offset set according to actual conditions, usually slightly larger than A m In general, each channel can be set with the same Δz m .

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

[0100] Assume that the incident light field from the beam excitation unit arm to the optical signal combining unit is E in =E0S(k), S(k) is the power spectral density function of the incident light, the reflected light of the optical signal combining unit enters the reference arm, and the transmitted light enters the sample arm. The reflected and transmitted power ratios of the optical signal combining unit are R and T respectively. The transmission and fiber coupling losses on the sample arm and the reference arm are considered to be η S,m ,η R , the power reflectances of the reference arm reflector and the mth channel test point are R S,m ,R R , then the interference light field obtained by the reflected light of the reference arm and the mth channel of the sample arm passing through the optical signal combining unit again is:

[0101]

[0102] Therefore, the interference light intensity is:

[0103]

[0104] Therefore, it can be seen that in the spectral domain (k wave number domain), the reflected light intensity 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 to be measured, the reflected optical path difference at each moment can be extracted through Fourier transform. Furthermore, by analyzing the change of the reflected optical path difference over time, the vibration frequency and vibration amplitude of the point to be measured can be obtained.

[0106] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A non-contact monitoring system for the vibration of a generator stator end, characterized in that: It includes a light beam excitation unit, a light signal combination unit, a control unit, a measurement unit, a control collection unit, a data analysis unit and a spectrum analysis unit; The light beam excitation unit is connected to the light signal combining unit, and the light beam excitation unit separates the laser light generated by the light beam excitation unit into reference light and detection light through the light signal combining unit; The optical signal combining unit is connected to the comparison unit and the measuring unit respectively, the reference light is input to the comparison unit to obtain the first reflected light; the detection light is input to the measuring unit to obtain the second reflected light; The output feedback of the comparison unit and the measurement unit is connected to the optical signal combination unit, and the first reflected light and the second reflected light are reflected back to the optical signal combination unit to obtain interference light; The control collection unit is connected to the optical signal combining unit through the spectrum analysis unit, receives the interference light, and obtains the output of the digital signal; 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 light beam excitation unit is connected to the light signal combining unit through an optical isolation component. The laser light generated by the light beam excitation unit passes through the optical isolation component and then enters the light signal combining unit.

3. The non-contact monitoring system for generator stator end vibration according to claim 1, characterized in that: The control unit includes a control unit switch, an adjustable attenuator, an electrically controlled optical fiber delay line, a lens assembly and a reflector; The control unit switch is electrically connected to the optical signal combining unit through an optical fiber; the control unit switch is electrically connected to the adjustable attenuator through an optical fiber; and the adjustable attenuator is electrically connected to the lens assembly through the electrically controlled optical fiber delay line.

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

5. The non-contact monitoring system for generator stator end vibration according to claim 3, characterized in that: The control and acquisition unit is electrically connected to the electrically controlled optical fiber delay line and sends a delay amount to the electrically controlled optical fiber delay line.

6. The non-contact monitoring system for generator stator end vibration according to claim 1, characterized in that: The measuring unit includes a variable gain amplifier, a polarization controller, a measuring unit multiplexer, a plurality of lens assemblies and a corresponding objective lens; The variable gain amplifier is electrically connected to the optical signal combining unit through optical fiber; the variable gain amplifier is electrically connected to the polarization controller through optical fiber; the polarization controller is electrically connected to the measurement unit multi-way switch through optical fiber; the measurement unit multi-way switch is electrically connected to each lens assembly through optical fiber pigtails; the center point of the lens assembly forms a 90° right angle with the corresponding center point of the objective lens and the detection point of the objective lens.

7. The non-contact monitoring system for generator stator end vibration according to claim 6, characterized in that: The control acquisition unit is electrically connected to the multi-way switch of the measurement unit, and sends a to-be-measured point selection instruction to the multi-way switch of the measurement unit.

8. The non-contact monitoring system for generator stator end vibration according to claim 1, characterized in that: The spectrum analysis unit comprises a two-way switch, a spectrum measurement component and a photoelectric detector; the two-way switch is connected to the spectrum measurement component and the photoelectric detector respectively.

9. A non-contact monitoring method for the vibration of a generator stator end, based on the non-contact monitoring system for the vibration of a generator stator end according to any one of claims 1 to 8, characterized in that: Methods include: S1: setting the delay amount of the electrically controlled optical fiber delay line to a preset value of the point i to be measured; S2: Setting the setting value of the variable gain amplifier at the point i to be measured by static calibration; S3: Connect the multi-way switch of the measuring unit to the point i to be measured; S4: using a spectrum analysis unit to obtain spectrum data of the point to be measured; S5: The spectrum data of the point to be measured is processed by the data analysis unit, and the next point to be measured is switched to until all the points are measured.

10. The non-contact monitoring method for generator stator end vibration according to claim 9, characterized in that: The specific process of the static calibration is as follows For the control unit, an electrically controlled optical fiber delay line scan is performed to calibrate the zero optical path delay of each measurement channel; Based on the zero optical path delay, add additional delay Δz m , as the setting value of the measurement channel; Obtain the optical power of the reference arm through the spectrum analysis unit, and close the optical switch of the reference arm; Turn on the multi-way switch of the measuring unit and select any point to be measured; The variable gain amplifier is controlled by controlling the acquisition unit so that the optical power of the measurement unit is consistent with that of the reference arm, and the setting value of the variable gain amplifier at this time is recorded and obtained.

Images