A flange joint bolt monitoring system and a monitoring method

Abstract

The present application relates to wind turbine flange connection bolt monitoring technical field, specifically to a kind of flange connection bolt monitoring system and monitoring method, wherein monitoring system includes fiber grating displacement sensor, fiber grating demodulator, data acquisition instrument and central processing unit, fiber grating displacement sensor is at least two, and evenly distributed on the inner circumference or outer circumference of flange connection, when flange is subjected to load, wavelength output by fiber grating displacement sensor changes, fiber grating demodulator analyzes and processes wavelength change, outputs corresponding relative displacement data, and relative displacement data is transmitted to central processing unit by data acquisition instrument, and central processing unit judges whether flange connection bolt appears loose according to received data.The flange connection bolt monitoring system provided by the present application can monitor the state of flange connection bolt, has high monitoring precision, and can accurately reflect the information of flange deformation with impeller angular position change, and the monitoring is more accurate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wind turbine flange connection bolt monitoring, in particular to a flange connection bolt monitoring system and a monitoring method. BACKGROUND

[0002] The basic principle of wind power generation is that the kinetic energy of wind is converted into mechanical energy by the wind turbine of the wind turbine generator, and then the generator of the wind turbine generator is driven to generate electricity to convert into electrical energy. Due to the interference of strong wind torque and the like, the connection bolt at the joint of the key part of the wind turbine generator is prone to loosening, which causes the wind turbine generator to fail to operate normally. For example, the connection bolt at the joint of the tower drum and the hub is loosened, causing cracks in the flange plate; the connection bolt at the joint of the wind turbine blade is loosened, causing the blade to fall off.

[0003] In order to prevent the reduction or disappearance of the bolt pretightening force, checking the bolt pretightening force with a torque wrench is an important part of regular maintenance. When the operation and maintenance is located in a remote area, the regular checking of the bolt pretightening force is generally performed once every six months. This work is time-consuming and labor-intensive, and is affected by the personal subjective factors and other objective factors of the staff, and cannot guarantee that the bolt loosening problem is found and eliminated in time each time, so it is necessary to monitor the bolt loosening on-line.

[0004] The technical scheme of monitoring the bolt loosening by monitoring the flange state through the installation of a sensor on the flange has the advantages of simple and intuitive principle, convenient field installation, high technical reliability, and the like. There are manufacturers on the market who have developed monitoring systems for monitoring bolt loosening by monitoring flange deformation. For example, patent CN202020349014.5 discloses a flange connection bolt loosening monitoring system, and patent CN202120961270.4 discloses a flange connection bolt monitoring system based on a split type displacement sensor. These two schemes monitor the bolt loosening by monitoring the flange gap or the relative displacement of the flange in the axial direction through a displacement sensor. However, in the above two schemes, an electromagnetic induction type displacement sensor is used. When the sensor is subjected to impact, high temperature or after long-term use, demagnetization problems may occur, resulting in a decrease in monitoring accuracy or even invalidity.

[0005] In addition, in recent years, wind turbine generators have developed towards large-scale, and the diameter of the impeller of some 4MW wind turbine generators has reached more than 150 meters. The wind speed at the lower part of the impeller is quite different from that at the upper part, there is a significant wind shear effect, and the self-weight is large. When the position of the impeller angle is different, the load on each flange of the wind turbine generator is different, and the flange deformation and the elongation of the flange connection bolt are also different. That is to say, the relative displacement of each flange monitored at different impeller angle positions is also different, and the relative displacement of each flange is dynamically changing. The existing technical scheme cannot accurately reflect the change of the flange deformation with the change of the position of the impeller angle, which affects the judgment of the monitoring result of the flange connection bolt. SUMMARY

[0006] In order to solve the above-mentioned deficiencies in the prior art, the present application provides a flange connecting bolt monitoring system, which can monitor the state of the flange connecting bolt, has high monitoring accuracy, and can accurately reflect the information of the flange deformation changing with the impeller angle position, and the monitoring is more accurate.

[0007] The technical scheme of the present application is as follows:

[0008] A flange connecting bolt monitoring system comprises a fiber grating displacement sensor, a fiber grating demodulator, a data acquisition instrument and a central processor, wherein the fiber grating displacement sensor is connected with the fiber grating demodulator, the fiber grating demodulator is connected with the data acquisition instrument, the data acquisition instrument is connected with the central processor, the fiber grating displacement sensor is at least two and is uniformly distributed on the inner or outer circumference of the flange connection, when the flange is subjected to a load, the wavelength output by the fiber grating displacement sensor changes, the fiber grating demodulator analyzes and processes the wavelength change, outputs the corresponding relative displacement data, and transmits the relative displacement data to the central processor through the data acquisition instrument, and the central processor judges whether the flange connecting bolt is loose according to the received data.

[0009] Further, the fiber grating displacement sensor comprises a sensor body and a pull rod connected with each other, the sensor body is fixed on the inner or outer circumferential sidewall of the lower flange through a gasket, the pull rod is fixed on the inner or outer circumferential sidewall of the upper flange through a mounting support, and the center lines of the sensor body and the pull rod are in the same straight line through the gasket and the mounting support; the sensor body and the gasket, the gasket and the lower flange, and the mounting support and the upper flange are all fixed by adhesion.

[0010] Further, the mounting support is a split structure, the mounting support comprises an upper support and a lower support, the lower support is fixedly connected to the upper flange, the upper support and the lower support are connected by screws, an installation hole is formed between the upper support and the lower support, and the end of the pull rod away from the sensor body is fixedly installed in the installation hole.

[0011] Further, the flange connecting bolt monitoring system further comprises an impeller angle position monitoring device, the impeller angle position monitoring device is connected to the data acquisition instrument and transmits the monitored impeller angle position information to the central processor through the data acquisition instrument, and the central processor matches the relative displacement data and the impeller angle position information, judges whether the flange connecting bolt is loose according to the relative displacement data of different impeller angle positions.

[0012] Further, the impeller rotation angle position monitoring device comprises a gravity acceleration sensor and a proximity sensor, wherein,

[0013] The gravity acceleration sensor is installed on the hub inner impeller rotation center axis, the center direction of the gravity acceleration sensor is perpendicular to the impeller rotation center axis, and the center direction of the gravity acceleration sensor points to the root position of the first blade, and the acceleration value measured by the gravity acceleration sensor changes with the different positions of the first blade;

[0014] The proximity sensor is fixedly installed on the cabin chassis, and the proximity sensor is arranged opposite to the circle where the main shaft mounting bolt is located. When the main shaft mounting bolt rotates to the position below the proximity sensor, the proximity sensor sends out a pulse signal or a high level signal.

[0015] The gravity acceleration sensor and the proximity sensor are connected with the data acquisition instrument, and the monitored data are transmitted to the central processor through the data acquisition instrument.

[0016] Further, the fiber grating displacement sensor is provided with a temperature sensor, the temperature is detected through the temperature sensor, the temperature data are transmitted to the central processor through the data acquisition instrument, the wavelength change caused by the temperature change is compensated, and the influence of the temperature change is eliminated.

[0017] Further, the rear end of the hub shell is provided with three groups of distance measuring devices corresponding to the three blades, each group of distance measuring devices comprises a plurality of laser distance measuring modules, and the plurality of laser distance measuring modules in each group of distance measuring devices are arranged in the length direction of the corresponding blade in sequence. The central processor calculates the deformation of each blade according to the received data, compensates the change of the relative displacement data caused by the deformation of the blade, and eliminates the influence of the deformation of each blade.

[0018] Further, the proximity sensor is fixedly installed on the cabin chassis through a mounting bracket, the mounting bracket is further provided with a first distance measuring sensor and a second distance measuring sensor, the first distance measuring sensor and the second distance measuring sensor are arranged opposite to the circle where the main shaft mounting bolt is located, when the main shaft mounting bolt rotates to the position below the proximity sensor, the first distance measuring sensor measures the distance from the end of the main shaft mounting bolt, and the second distance measuring sensor measures the distance from the bolt mounting end face on the main shaft.

[0019] Another aspect of the present application provides a monitoring method of the flange connection bolt monitoring system as described above, for monitoring the flange connection bolts at the connection between the hub shell and the nacelle underframe and monitoring the flange connection bolts at the connection of each blade, comprising the following steps:

[0020] S1, installing fiber grating displacement sensors, gravity acceleration sensors, proximity sensors, three sets of distance measuring devices, first distance measuring sensors and second distance measuring sensors at the corresponding positions of the connection between the hub shell and the nacelle underframe in the wind turbine, and installing fiber grating displacement sensors at the corresponding positions of the connection of each blade, wherein each fiber grating displacement sensor is connected with a fiber grating demodulator, the fiber grating demodulator, the gravity acceleration sensor, the proximity sensor are all connected with a data acquisition instrument, and the data acquisition instrument is connected with a central processor;

[0021] S2, when the wind turbine is working, the central processor receives and stores the data monitored by the fiber grating displacement sensors, the gravity acceleration sensors, the proximity sensors, the three sets of distance measuring devices, the first distance measuring sensors and the second distance measuring sensors through the data acquisition instrument;

[0022] S3, the central processor analyzes the data monitored by the gravity acceleration sensors and the proximity sensors to obtain the position information of the blade wheel angle;

[0023] Specifically, when the first blade where the gravity acceleration sensor is located is at the lowermost end of the blade wheel, the acceleration value measured by the gravity acceleration sensor is the largest, at this time the angle of the blade wheel is the initial value, the proximity sensor is counted, if there are N main shaft mounting bolts in one circle, then the main shaft angle corresponding to the front and rear pulse signals or high level signals emitted by the proximity sensor is 360 / N degrees, that is, the angle of the blade wheel is also 360 / N degrees, according to the counting condition of the pulse signals or high level signals emitted by the proximity sensor, the position of the blade wheel angle is judged;

[0024] S4, the central processor matches the relative displacement data at the same time point with the position information of the blade wheel angle to obtain real-time information of the relative displacement data changing with the position of the blade wheel angle;

[0025] S5, the central processor analyzes and processes the relative displacement data at different blade wheel angle positions to judge whether the flange connection bolts are loose;

[0026] Specifically, the analyzed and processed relative displacement data is compared with the existing relative displacement data at the same blade wheel angle position obtained through test or simulation, when the difference between the two relative displacement data reaches the safety threshold, it means that the bolt loosening problem has occurred, at this time the central processor prompts the bolt loosening position according to the difference between the first distance measuring sensor and the second distance measuring sensor under the detectable accuracy.

[0027] Further, in the step S5, the central processor analyzes and processes the relative displacement data of different impeller angle positions, specifically including:

[0028] S51, the relative displacement data of the fiber grating displacement sensor at the connection between the hub shell and the nacelle chassis is analyzed and processed to obtain:

[0029] D(θ)=D c (θ)-D t -D x

[0030] Wherein, D(θ) is the relative displacement data of the fiber grating displacement sensor at the connection between the hub shell and the nacelle chassis after analysis and processing under different impeller angles, D c (θ) is the relative displacement data monitored by the fiber grating displacement sensor at the connection between the hub shell and the nacelle chassis under different impeller angles, D t is the displacement change caused by temperature, D x is the displacement change caused by the overall deformation of the three blades, and θ is the impeller angle.

[0031] S52, the relative displacement data of the fiber grating displacement sensor at the connection of each blade is analyzed and processed to obtain:

[0032] d(θ)=d c (θ)-d t -d x -d l

[0033] d′(θ)=d′ c (θ)-d′ t -d′ x -d l

[0034] d″(θ)=d″ c (θ)-d″ t -d″ x -d l

[0035] Wherein, d(θ), d′(θ) and d″(θ) are the relative displacement data of the fiber grating displacement sensor at the connection of the first blade, the second blade and the third blade after analysis and processing, d c (θ), d′ c (θ), d″ c (θ) are the relative displacement data monitored by the fiber grating displacement sensor at the connection of the first blade, the second blade and the third blade under different impeller angles, d t , d′ t , d″ td x d′ x d″ x d l d is the displacement variation caused by different rotating speeds.

[0036] Compared with the prior art, the present application has the following beneficial effects:

[0037] 1. The present application can monitor the deformation (relative displacement) of each flange (such as the hub shell and the cabin bottom frame connection and each blade connection) of the wind turbine through the arrangement of the fiber grating displacement sensor, thereby monitoring the state of each flange connection bolt. The fiber grating displacement sensor has high monitoring precision, high long-term application reliability, and no monitoring precision decline problem caused by magnetic decay.

[0038] 2. The end of the pull rod of the fiber grating displacement sensor away from the sensor body is fixed by the upper support, the lower support and the bolt. The installation is convenient, and the distance between the lower surface of the lower support and the upper surface of the gasket at the sensor body can be quickly adjusted by adjusting the position of the upper support and the lower support on the pull rod, thereby adapting to different monitoring distance application sites.

[0039] 3. The present application monitors the impeller angle position information through the arrangement of the impeller angle position monitoring device, and matches the flange deformation (relative displacement data) at the same time with the impeller angle position information through the central processing unit, thereby accurately reflecting the flange deformation change information with the impeller angle position, avoiding the calculation of the flange load (deformation) caused by the different impeller angle positions into the flange connection bolt deformation in the later flange deformation monitoring, and affecting the judgment of the flange connection bolt monitoring result.

[0040] 4. The impeller angle position monitoring device of the present application comprises a gravity acceleration sensor and a proximity sensor. The wind turbine impeller angle position information can be monitored through the arrangement of the gravity acceleration sensor and the proximity sensor. The monitoring principle is simple, the reliability is high, and the error is small.

[0041] 5. The present application compares the monitored flange relative displacement data with the existing flange relative displacement data at the same impeller angle position through test or simulation after analyzing and processing the monitored flange relative displacement data, judges the bolt loosening problem, eliminates the influence of the impeller angle position on the flange relative displacement data, and has high flange connection bolt monitoring precision and long bolt service life. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 Figure 1 is a top view of the installation of the fiber grating displacement sensor in the corresponding flange connection in the present application;

[0043] Figure 2 Figure 2 is a structural schematic diagram of the fiber grating displacement sensor in the present application;

[0044] Figure 3 Figure 3 is a front view of the installation of the fiber grating displacement sensor in the corresponding flange connection in the present application;

[0045] Figure 4 Figure 4 is a side view of the installation of the fiber grating displacement sensor in the corresponding flange connection in the present application;

[0046] Figure 5 Figure 5 is a structural schematic diagram of the upper support in the present application;

[0047] Figure 6 Figure 6 is a structural schematic diagram of the lower support in the present application;

[0048] Figure 7 Figure 7 is a perspective view of the installation of the gravitational acceleration sensor and the distance measuring device in the hub in the present application;

[0049] Figure 8 Figure 8 is a front view of the installation of the gravitational acceleration sensor in the hub in the present application;

[0050] Figure 9 Figure 9 is a structural schematic diagram of the installation support in the present application;

[0051] Figure 10 Figure 10 is a schematic diagram of the connection of the proximity sensor, the first distance measuring sensor, and the second distance measuring sensor with the support in the present application;

[0052] Figure 11 Figure 11 is a top view of the installation of the proximity sensor on the cabin chassis in the present application;

[0053] Figure 12 Figure 12 is a side view of the installation of the proximity sensor on the cabin chassis in the present application;

[0054] Figure 1 is a top view of the installation of the fiber grating displacement sensor in the corresponding flange connection in the present application;

[0055] 100 - impeller rotation center axis, 200 - center direction of gravity acceleration sensor, 300 - first blade, 400 - second blade, 500 - third blade, 600 - nacelle chassis, 700 - main shaft, 800 - main shaft mounting bolt. DETAILED DESCRIPTION

[0056] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not intended to limit the present application and its application or use in any way. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0057] It should be noted that the terms used herein are only intended to describe specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, operation, device, component and / or combination thereof.

[0058] In addition, it should be noted that the use of the terms "first", "second" and the like to qualify parts is only intended to facilitate the distinction of the corresponding parts, and unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present application.

[0059] The embodiment provides a flange connection bolt monitoring system based on a fiber grating displacement sensor 1, comprising a plurality of fiber grating displacement sensors 1, a fiber grating demodulator (not shown in the figure), a data acquisition instrument (not shown in the figure) and a central processor (not shown in the figure), wherein the fiber grating displacement sensor 1 is connected with the fiber grating demodulator, the fiber grating demodulator is connected with the data acquisition instrument, the data acquisition instrument is connected with the central processor, and data transmission is performed.

[0060] The fiber grating displacement sensor 1 is at least two, and is uniformly distributed on the inner or outer circumference of the flange connection, as shown in the figure, the fiber grating displacement sensor 1 in the embodiment is uniformly distributed with four on the inner circumference of the flange connection of the hub shell and the nacelle chassis 600, and is uniformly distributed with four on the inner circumference of the flange connection of the three blades respectively. Figure 1

[0061] ​Specifically, each fiber grating displacement sensor 1 comprises a sensor body 11 and a pull rod 12 connected with each other, as shown in the figure Figures 2-6 The sensor body 11 is fixed to the inner circumferential side wall of the lower flange 22 through the gasket 3, and the sensor body 11 and the gasket 3 and the gasket 3 and the lower flange 22 are all fixed by adhesion. The pull rod 12 is fixed to the inner circumferential side wall of the upper flange 21 through the mounting support 4, and the mounting support 4 and the upper flange 21 are all fixed by adhesion. Further, the mounting support 4 is of split structure, comprising an upper support 41 and a lower support 42, the lower support 42 is adhesively fixed to the inner circumferential side wall of the upper flange 21, the upper support 41 and the lower support 42 are connected by screws, and the mounting hole 43 is formed between the upper support 41 and the lower support 42, the end of the pull rod 12 away from the sensor body 11 is fixedly installed in the mounting hole 43, and the gasket 3 and the mounting support 4 are arranged to make the center lines of the sensor body 11 and the pull rod 12 in the same straight line.

[0062] When the flange 2 is subjected to load (flange deformation), the relative displacement (strain) between the upper surface of the gasket 3 and the lower surface of the lower support 42 is caused, so that the wavelength output by the fiber grating displacement sensor 1 is changed, the fiber grating demodulator is connected with the fiber grating displacement sensor 1 through a cable, and after analyzing the wavelength change transmitted by the fiber grating displacement sensor 1, the wavelength information and the relative displacement data between the sensor body 11 and the pull rod 12 of the fiber grating displacement sensor 1 (flange relative displacement data) can be determined, the data is sent to the data acquisition instrument by the fiber grating demodulator, and finally the data is transmitted to the central processor for processing by the data acquisition instrument in a wired or wireless manner. When the wind turbine is in working condition, the relative displacement change between the upper surface of the gasket 3 and the lower surface of the lower support 42 can be monitored in real time by the fiber grating displacement sensor 1 and the fiber grating demodulator installed on the flange 2, the central processor stores and analyzes the relative displacement change data, and according to the corresponding information between the relative displacement change data of the fiber grating displacement sensor 1 and the bolt loosening degree under a certain wind speed obtained by experiment or CAE analysis, when the relative displacement value reaches a certain value, it is indicated that the bolt loosening problem has occurred.

[0063] In order to eliminate the influence of the impeller rotation angle position on the flange connection bolt monitoring and judgment, the monitoring system provided in the embodiment further comprises an impeller rotation angle position monitoring device, specifically, as shown in the figure Figures 7-8As shown, the impeller rotation angle position monitoring device comprises a gravity acceleration sensor 5 and a proximity sensor 6, wherein the gravity acceleration sensor 5 is installed on the impeller rotation center axis 100 in the hub, the center direction 200 of the gravity acceleration sensor is perpendicular to the impeller rotation center axis 100, and the center direction 200 of the gravity acceleration sensor points to the root position of the first blade 300, the acceleration value measured by the gravity acceleration sensor 5 changes with the position of the first blade 300, and when the first blade 300 is at the lowermost end of the impeller, the acceleration value measured by the gravity acceleration sensor 5 is the largest, and the time point when the first blade 300 is at the lowermost end of the impeller can be accurately monitored. Further, the proximity sensor 6 is fixedly installed on the cabin chassis 600 through a mounting bracket 7, and the bracket structure is as shown in Figures 9-10 As shown, the bracket is provided with a fixing seat 71 and a first fixing hole 72, one end (the fixing seat 71) of the bracket is fixedly connected to the cabin chassis 600 through bonding, and the other end (the first fixing hole 72) of the bracket extends above the circle where the main shaft mounting bolt 800 is located, and the proximity sensor 6 is fixedly installed on the first fixing hole 72, as shown in Figure 11 As shown, the proximity sensor 6 is arranged opposite to the circle where the main shaft mounting bolt 800 is located, and the main shaft mounting bolt 800 rotates with the main shaft 700, and when the main shaft mounting bolt 800 rotates below the proximity sensor 6, the proximity sensor 6 sends out a pulse signal or a high-level signal.

[0064] The gravity acceleration sensor 5 and the proximity sensor 6 are connected with a data acquisition instrument, and the monitored data are transmitted to a central processor through the data acquisition instrument, the central processor stores and analyzes the data to obtain the impeller rotation angle position information, the central processor matches the relative displacement data and the impeller rotation angle position information, and the information that the flange deformation changes with the impeller rotation angle position can be accurately reflected, and whether the flange connecting bolt is loose is judged according to the actual monitored relative displacement data of different impeller rotation angle positions and the existing relative displacement data obtained through test or CAE simulation analysis under a certain wind speed and at the same impeller rotation angle position.

[0065] When the existing wind turbine model is tested or simulated, it is generally performed under specific temperature, specific wind speed and the like, and the shape of the blade remains stable; however, when the wind turbine is actually working, the temperature and the wind speed will change, and the blade will also deform, so when the actual monitored relative displacement data is compared with the existing data, although the data comparison can be performed at the same blade rotation angle position to eliminate the influence of the blade rotation angle position, other factors such as temperature, wind speed and blade deformation will also affect the relative displacement data of each fiber grating displacement sensor 1. Therefore, it is necessary to analyze and process the monitored relative displacement data, so that the monitored relative displacement data is converted into data under the same environment as the existing relative displacement data, and then the comparison is performed.

[0066] In this regard, in this embodiment, a temperature sensor is provided in each fiber Bragg grating displacement sensor 1 to detect the temperature, and the temperature data is transmitted to the central processing unit via a data acquisition device to compensate for the wavelength change caused by the temperature change and eliminate the influence of the temperature change.

[0067] Furthermore, if Figure 7 As shown, in this embodiment, three groups of distance measuring devices 8 are provided at the rear end of the hub shell corresponding to the three blades. Each group of distance measuring devices 8 includes a plurality of laser distance measuring modules. The plurality of laser distance measuring modules in each group of distance measuring devices 8 are arranged in sequence in the length direction of the corresponding blades. The three groups of distance measuring devices 8 send the data of each laser distance measuring module to the central processing unit via the data acquisition device. The central processing unit calculates the deformation of each blade based on the received data, compensates for the change in relative displacement data caused by the blade deformation, and eliminates the influence of the blade deformation.

[0068] Furthermore, in this embodiment, a second mounting hole 73 and a third mounting hole 74 are provided on the mounting bracket 7 to respectively install a first ranging sensor 91 and a second ranging sensor 92. The first ranging sensor 91 and the second ranging sensor 92 are arranged opposite to the circle where the spindle mounting bolt 800 is located. The first ranging sensor 91 is arranged close to the proximity sensor 6, and the distance between the two is less than the length of the bolt end. The second ranging sensor 92 is arranged close to the first ranging sensor 91, and the distance between the second ranging sensor 92 and the proximity sensor 6 is greater than the length of the bolt end. When the spindle mounting bolt 800 is rotated to the bottom of the proximity sensor 6, the first ranging sensor 91 measures the distance between it and the end of the spindle mounting bolt 800, and the second ranging sensor 92 measures the distance between it and the bolt mounting end face on the spindle 700.

[0069] The present invention also provides a monitoring method for the flange connection bolt monitoring system, which is used to monitor the flange connection bolts at the connection between the hub shell and the nacelle chassis 600 and the flange connection bolts at the connection of each blade, comprising the following steps:

[0070] S1. Install a fiber Bragg grating displacement sensor 1, a gravity acceleration sensor 5, a proximity sensor 6, three sets of distance measuring devices 8, a first distance measuring sensor 91, and a second distance measuring sensor 92 at corresponding positions at the connection (flange connection) between the hub shell and the nacelle chassis 600 in the wind turbine generator set; install a fiber Bragg grating displacement sensor 1 at corresponding positions at the connection (flange connection) of each blade; these fiber Bragg grating displacement sensors 1 are all connected to a fiber Bragg grating demodulator, and the fiber Bragg grating demodulator, gravity acceleration sensor 5, and proximity sensor 6 are all connected to a data acquisition device, and the data acquisition device is connected to a central processing unit;

[0071] S2, when the wind turbine is working, the central processor receives and stores the data monitored by the fiber bragg grating displacement sensor 1 (fiber bragg grating demodulator), the gravity acceleration sensor 5, the proximity sensor 6, the three sets of distance measuring devices 8, the first distance measuring sensor 91 and the second distance measuring sensor 92 through the data acquisition instrument respectively;

[0072] S3, the central processor analyzes the data monitored by the gravity acceleration sensor 5 and the proximity sensor 6 to obtain the position information of the wind turbine impeller rotation angle;

[0073] Specifically, when the wind turbine is working, the acceleration value measured by the gravity acceleration sensor 5 installed in the impeller hub changes with the position of the first blade 300. When the first blade 300 where the gravity acceleration sensor 5 is located is at the lowermost end of the impeller, the acceleration value measured by the gravity acceleration sensor 5 is the maximum, and the time point when the first blade 300 is at the lowermost end of the impeller can be accurately monitored. At this time, the rotation angle of the impeller is the initial value zero position. Then count the proximity sensor 6. If there are N main shaft mounting bolts 800 in one circle, the main shaft rotation angle corresponding to the two pulse signals or high level signals sent by the proximity sensor 6 is 360 / N degrees, that is, the rotation angle of the impeller is also 360 / N degrees. According to the counting condition of the pulse signal or high level signal sent by the proximity sensor 6, the position of the impeller rotation angle is judged.

[0074] S4, the central processor matches the relative displacement data and the position information of the impeller rotation angle at the same time point to obtain the real-time information that the relative displacement data changes with the position of the impeller rotation angle, that is, the information that the deformation of the flange 2 changes with the position of the impeller rotation angle.

[0075] S5, the central processor analyzes and processes the relative displacement data at different positions of the impeller rotation angle to judge whether the flange connecting bolt 23 is loose;

[0076] Among them, the central processor analyzes and processes the relative displacement data at different positions of the impeller rotation angle, specifically including:

[0077] S51, analyze and process the relative displacement data of the fiber bragg grating displacement sensor 1 at the connection between the hub shell and the nacelle chassis 600 to obtain:

[0078] D (θ) = D c (θ)-D t -D x

[0079] Among them, D (θ) is the relative displacement data of the fiber bragg grating displacement sensor 1 at the connection between the hub shell and the nacelle chassis 600 at different positions of the impeller rotation angle; D c(θ) is the relative displacement data monitored by the fiber Bragg grating displacement sensor 1 at the connection between the hub shell and the nacelle chassis 600 at different impeller rotation angles, obtained through actual measurement of each fiber Bragg grating displacement sensor; D t D is the displacement change caused by temperature at the connection between the hub shell and the nacelle chassis 600, that is, the displacement change caused by the difference between the temperature measured by each temperature sensor and the temperature of the existing data; x is the displacement change caused by the overall deformation of the three blades. The multiple distances measured by each distance measuring device can be used to obtain the slopes of multiple measured points on each blade. The displacement change caused by the overall deformation is calculated in combination with the shape of each blade. Alternatively, a data table of the overall displacement change and the slopes of multiple measured points is pre-formed through simulation. The overall displacement change is obtained by looking up the table based on the slope data of the current multiple measured points. θ is the impeller angle.

[0080] S52, analyzing and processing the relative displacement data of the fiber Bragg grating displacement sensor 1 at each blade connection to obtain:

[0081] d(θ)=d c (θ)-d t -d x -d l

[0082] d′(θ)=d′ c (θ)-d′ t -d′ x -d l

[0083] d″(θ)=d″ c (θ)-d″ t -d″ x -d l

[0084] Wherein, d(θ), d′(θ) and d″(θ) are the relative displacement data of the fiber Bragg grating displacement sensor 1 at the first blade connection, the second blade connection and the third blade connection after analysis and processing respectively; d c (θ), d′ c (θ), d″ c (θ) are the relative displacement data monitored by the fiber Bragg grating displacement sensor 1 at the connection of the first blade, the connection of the second blade, and the connection of the third blade at different impeller rotation angles, which are obtained by actual measurement of each fiber Bragg grating displacement sensor; d t , d′ t , d″ t is the displacement change caused by the temperature at the first blade connection, the second blade connection, and the third blade connection, that is, the displacement change caused by the difference between the actual temperature measured by each temperature sensor and the temperature of the existing data; d x, d' x , d" x The displacement variation amounts caused by the first blade deformation, the second blade deformation and the third blade deformation are respectively d', d" and d'". The slopes of the multiple measured points on each blade can be obtained by the multiple distances measured by each distance measuring device. The displacement variation amounts are calculated in combination with the shape of each blade, or a data table of displacement variation amounts and slopes of multiple measured points is formed in advance through simulation. The displacement variation amounts are obtained by looking up the table according to the slope data of the current multiple measured points. l d is the displacement variation amount caused by different rotating speeds, that is, the displacement variation amount caused by different centrifugal forces due to the difference between the current rotating speed and the rotating speed corresponding to the existing data. The rotating speed can be obtained according to the interval time between two signals of the proximity sensor and the arc length of the circle where the two adjacent main shaft mounting bolts are located. The flange connection of each blade is monitored and judged according to the above formula.

[0085] Then, the analyzed relative displacement data is compared with the existing relative displacement data of the same impeller angle position obtained through test or simulation. When the difference between the two relative displacement data reaches the safety threshold, it indicates that the bolt loosening problem has occurred, prompting the staff to overhaul.

[0086] In the traditional flange connection bolt detection system, the existing relative displacement data for comparison at different impeller angle positions is the same value. Due to wind shear and self-weight, the actual measured relative displacement data is allowed to fluctuate in a relatively large range around the same value, that is, the range of the data interval that meets the requirements is relatively large. In this way, the relative displacement data at any angle position can meet the requirements, so as not to be misjudged, and the monitoring and judging accuracy is very low. In the embodiment, the high-precision fiber Bragg grating displacement sensor is used in combination with the angle position monitoring device to monitor the relative displacement data at different blade angle positions, which is then compared with the existing relative displacement data at the same blade angle position. The allowed fluctuation range of the relative displacement data at each angle position monitored can be set very small, and the accuracy is very high.

[0087] When the new bolt is just installed, the working environment of the wind turbine is different from the environment corresponding to the existing data, and it is impossible to determine whether the bolt after installation deviates from the design value. For example, although the relative displacement data monitored by the fiber Bragg grating displacement sensor is within the allowed range, the measured data is actually out of the allowed range due to the influence of temperature or blade deformation. Therefore, the embodiment considers factors such as temperature, wind speed and blade deformation, and converts the data of the wind turbine under the current actual working environment into data under the same environment corresponding to the existing data, so as to prevent misjudgment caused by displacement variation amounts due to these factors. If the design value is found to be inconsistent when newly installed, the bolt can be replaced immediately, which can improve the service life of the bolt.

[0088] In the subsequent work process of the wind turbine, the flange connections are continuously monitored, and the difference between the first distance sensor 91 and the second distance sensor 92 during the subsequent work is compared with the difference recorded during the initial operation. When the analyzed and processed relative displacement data exceeds the limit, the approximate position of the loose bolt is prompted. For example, when a bolt is detected, if the difference between the first distance sensor 91 and the second distance sensor 92 is greater than the difference recorded during the initial operation, the position of the bolt is displayed, thereby improving the maintenance efficiency. It should be noted that since the detection accuracy of the distance sensor is slightly lower than that of the fiber Bragg grating displacement sensor 1, only the detection accuracy of the distance sensor is realized.

[0089] From the above, it can be seen that the flange connection bolt monitoring system provided in the embodiment can monitor the state of the flange connection bolt, has high monitoring accuracy, and can accurately reflect the information of the change of the flange deformation with the blade wheel angle position, and the monitoring is more accurate.

[0090] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can make equivalent replacements or changes to the technical range disclosed in the present application according to the technical solution and inventive concept of the present application, which should be covered within the protection scope of the present application.

Claims

1. A flange joint bolt monitoring system characterized by, The system comprises a fiber grating displacement sensor (1), a fiber grating demodulator, a data acquisition instrument and a central processor, wherein the fiber grating displacement sensor (1) is connected with the fiber grating demodulator, the fiber grating demodulator is connected with the data acquisition instrument, the data acquisition instrument is connected with the central processor, the fiber grating displacement sensor (1) is at least two and is uniformly distributed on the inner or outer circumferential wall of the flange connection, when the flange (2) is subjected to load, the wavelength output by the fiber grating displacement sensor (1) changes, the fiber grating demodulator analyzes and processes the wavelength change, outputs the corresponding relative displacement data, and transmits the relative displacement data to the central processor through the data acquisition instrument, and the central processor judges whether the flange connection bolt (23) is loose according to the received data. The flange connection bolt monitoring system is used for monitoring the flange connection bolts at the connection between the hub shell and the nacelle undercarriage (600) and monitoring the flange connection bolts at the connection of each blade; the rear end of the hub shell is provided with three groups of distance measuring devices (8) corresponding to three blades, each group of distance measuring devices (8) comprises a plurality of laser distance measuring modules, and the plurality of laser distance measuring modules in each group of distance measuring devices (8) are arranged in the length direction of the corresponding blade in sequence; the three groups of distance measuring devices (8) send the data of the laser distance measuring modules to the central processor through the data acquisition instrument, and the central processor calculates the deformation of each blade according to the received data, compensates the change of the relative displacement data caused by the deformation of the blade, and eliminates the influence of the deformation of each blade.

2. The flange joint bolt monitoring system according to claim 1, characterized by, The fiber grating displacement sensor (1) comprises a sensor body (11) and a pull rod (12) connected with each other, the sensor body (11) is fixed on the inner or outer circumferential side wall of the lower flange (22) through a gasket (3), the pull rod (12) is fixed on the inner or outer circumferential side wall of the upper flange (21) through a mounting support (4), and the center lines of the sensor body (11) and the pull rod (12) are in the same straight line through the gasket (3) and the mounting support (4); the sensor body (11) and the gasket (3), the gasket (3) and the lower flange (22), and the mounting support (4) and the upper flange (21) are fixed through adhesion.

3. The flange joint bolt monitoring system according to claim 2, wherein The mounting support (4) is a split structure, the mounting support (4) comprises an upper support (41) and a lower support (42), the lower support (42) is fixedly connected to the upper flange (21), the upper support (41) and the lower support (42) are connected through screws, an installation hole (43) is formed between the upper support (41) and the lower support (42), and one end of the pull rod (12) away from the sensor body (11) is fixedly installed in the installation hole (43).

4. The flange joint bolt monitoring system according to claim 3, wherein The flange connecting bolt monitoring system further comprises an impeller rotation angle position monitoring device connected to the data acquisition instrument and transmitting the monitored impeller rotation angle position information to the central processor via the data acquisition instrument, and the central processor matches the relative displacement data and the impeller rotation angle position information to determine whether the flange connecting bolt (23) is loose according to the relative displacement data at different impeller rotation angle positions.

5. The flange joint bolt monitoring system according to claim 4, wherein The impeller rotation angle position monitoring device comprises a gravity acceleration sensor (5) and a proximity sensor (6), wherein, The gravity acceleration sensor (5) is installed on the impeller rotation center axis (100) in the hub, the central direction (200) of the gravity acceleration sensor (5) is perpendicular to the impeller rotation center axis (100), and the central direction (200) of the gravity acceleration sensor (5) points to the root position of the first blade (300), and the acceleration value measured by the gravity acceleration sensor (5) changes with the position of the first blade (300); The proximity sensor (6) is fixedly installed on the cabin chassis (600), and the proximity sensor (6) is arranged opposite to the circle where the main shaft mounting bolt (800) is located. The main shaft mounting bolt (800) rotates with the main shaft (700), and when the main shaft mounting bolt (800) rotates below the proximity sensor (6), the proximity sensor (6) sends out a pulse signal or a high level signal. The gravity acceleration sensor (5) and the proximity sensor (6) are connected with the data acquisition instrument, and the monitored data is transmitted to the central processor via the data acquisition instrument, and the central processor stores and analyzes the data to obtain the impeller rotation angle position information.

6. The flange joint bolt monitoring system according to claim 5, wherein The temperature sensor is arranged in the fiber grating displacement sensor (1), the temperature sensor detects the temperature, and the temperature data is transmitted to the central processor via the data acquisition instrument, the wavelength change caused by the temperature change is compensated, and the influence of the temperature change is eliminated.

7. The flange joint bolt monitoring system according to claim 6, wherein The proximity sensor (6) is fixedly installed on the cabin chassis (600) through the mounting bracket (7), and the first distance measuring sensor (91) and the second distance measuring sensor (92) are further arranged on the mounting bracket (7), the first distance measuring sensor (91) and the second distance measuring sensor (92) are arranged opposite to the circle where the main shaft mounting bolt (800) is located, when the main shaft mounting bolt (800) rotates below the proximity sensor (6), the first distance measuring sensor (91) measures the distance from the end of the main shaft mounting bolt (800), and the second distance measuring sensor (92) measures the distance from the bolt mounting end face on the main shaft (700).

8. A monitoring method of the flange joint bolt monitoring system according to claim 7, characterized by, The method comprises the following steps: S1, install fiber bragg grating displacement sensor (1), gravity acceleration sensor (5), proximity sensor (6), three sets of distance measuring devices (8), first distance measuring sensor (91) and second distance measuring sensor (92) at the corresponding position of the connection between the hub shell and the nacelle chassis (600), and install fiber bragg grating displacement sensor (1) at the corresponding position of the connection between each blade, wherein the fiber bragg grating displacement sensor (1) is connected with the fiber bragg grating demodulator, the fiber bragg grating demodulator, the gravity acceleration sensor (5), the proximity sensor (6) are connected with the data acquisition instrument, and the data acquisition instrument is connected with the central processor; S2, when the wind turbine is working, the central processor receives and stores the data monitored by the fiber bragg grating displacement sensor (1), the gravity acceleration sensor (5), the proximity sensor (6), the three sets of distance measuring devices (8), the first distance measuring sensor (91) and the second distance measuring sensor (92) through the data acquisition instrument; S3, the central processor analyzes the data monitored by the gravity acceleration sensor (5) and the proximity sensor (6) to obtain the blade wheel angle position information; Specifically, when the first blade (300) where the gravity acceleration sensor (5) is located is at the lowermost end of the blade wheel, the acceleration value measured by the gravity acceleration sensor (5) is the maximum, and at this time, the angle of the blade wheel is the initial value. Count the proximity sensor (6), if there are N main shaft mounting bolts (800) in one circle, then the main shaft angle corresponding to the front and rear pulse signals or high level signals emitted by the proximity sensor (6) is 360 / N degrees, that is, the angle of the blade wheel is also 360 / N degrees. According to the counting condition of the pulse signal or high level signal emitted by the proximity sensor (6), the blade wheel angle position is determined; S4, the central processor matches the relative displacement data at the same time point with the blade wheel angle position information to obtain real-time information of the relative displacement data changing with the blade wheel angle position; S5, the central processor analyzes and processes the relative displacement data at different blade wheel angle positions to determine whether the flange connecting bolt is loose; Specifically, the analyzed and processed relative displacement data is compared with the existing relative displacement data at the same blade wheel angle position obtained through test or simulation. When the difference between the two relative displacement data reaches the safety threshold, it means that the bolt loosening problem has occurred. At this time, the central processor prompts the bolt loosening position according to the difference between the first distance measuring sensor (91) and the second distance measuring sensor (92) under the detectable accuracy.

9. The monitoring method of the flange joint bolt monitoring system according to claim 8, characterized by, In the step S5, the central processor analyzes and processes the relative displacement data at different blade wheel angle positions, specifically including: S51, analyze and process the relative displacement data of the fiber bragg grating displacement sensor (1) at the connection between the hub shell and the nacelle chassis (600) to obtain: D(θ) = D c (θ) - D t -D x Wherein, D(θ) is the relative displacement data of the optical fiber grating displacement sensor (1) at the connecting position of the hub shell and the nacelle underbody (600) under different impeller rotation angles after analysis and processing, D c (θ) is the relative displacement data of the optical fiber grating displacement sensor (1) at the connecting position of the hub shell and the nacelle underbody (600) under different impeller rotation angles, D t is the displacement change caused by temperature, D x is the displacement change caused by the overall deformation of the three blades, and θ is the impeller rotation angle. S52, analyze and process the relative displacement data of the fiber bragg grating displacement sensor (1) at the connection between each blade to obtain: d(θ) = d c (θ) - d t - d x - d l d'(θ) = d c (θ) - d t - d x - d l d"(0) = d"c(0) - d" t -d" x -d l Wherein, d(θ), d'(θ) and d''(θ) are the relative displacement data of the fiber grating displacement sensor (1) at the first blade joint, the second blade joint and the third blade joint after analysis and processing, respectively, d c (θ), d' c (θ), d'' c (θ) are the relative displacement data of the fiber grating displacement sensor (1) at the first blade joint, the second blade joint and the third blade joint under different impeller angles, respectively, d t , d' t , d'' t are the displacement change amounts caused by temperature at the first blade joint, the second blade joint and the third blade joint, respectively, d x , d' x , d'' x are the displacement change amounts caused by the first blade deformation, the second blade deformation and the third blade deformation, respectively, d l is the displacement change amount caused by different rotating speeds.

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