An online monitoring system and method for bolts of a wind turbine generator

Abstract

The application provides a bolt online monitoring system and method of a wind power generator set, relates to the technical field of wind power installation equipment detection and analysis, and comprises a detection module, a sensor module, an A / D conversion module, a temperature calibration module, a signal processing module, a network communication module and a monitoring platform. The first detection optical cable and the second detection optical cable are arranged on the body and the bolt of the wind power generator set respectively and detect the backscattering light at the light source incident ports of the two, the OTDR technology is used to monitor the bolt, the first detection optical cable fixed on the body of the wind power generator set is used as a reference to measure the relative change amount of the second detection optical cable, the bolt at each position can be monitored more directly, the influence of the interference signal on the measurement result can be reduced, and the measurement result is corrected by using the temperature sensor, so that the final measurement result is more accurate.

Description

Technical Field

[0001] This invention relates to the field of wind power installation equipment testing and analysis technology, specifically to an online monitoring system and method for bolts of wind turbine generator sets. Background Technology

[0002] During long-term use, some bolts on wind turbines may loosen, fall off, or break, posing safety hazards and even causing irreversible damage to the equipment. Because many of these bolts are located tens of meters in the air, it is difficult to monitor them manually. Currently, commonly used detection methods include OTDR testing, strain gauge electrical testing, ultrasonic testing, and passive RFID tag technology.

[0003] An Optical Time-Domain Reflectometer (OTDR) is a commonly used fiber optic measurement instrument used to evaluate the performance of fiber optic connections and detect faults in the fiber. It analyzes the fiber's characteristics by sending high-energy, short-pulse optical signals to the fiber under test and measuring Rayleigh scattering and the scattered light signals within the fiber. The horizontal axis corresponds to the propagation time of the backscattered light in terms of distance, while the vertical axis represents the intensity of the scattered light in dB and is displayed on the screen. This allows the optical pulse round-trip time to be converted into fiber length on the horizontal axis, directly observing changes in the transmitted optical power along the entire fiber optic line. When a bolt at a certain location loosens or falls off, the fiber at that point deforms under stress, causing a change in the intensity of the scattered light, which is detected, thus enabling online monitoring of the bolt.

[0004] Chinese Patent Publication No. CN109058054A, published on December 21, 2018, discloses an online bolt monitoring system and method for wind turbine generator sets. It determines whether a bolt has loosened or fallen off by detecting changes in the intensity of interference light at the corresponding bolt positions. The phase difference of the interference light is obtained by comparing the light intensity before and after the bolt loosens, thus detecting the severity of the loosening. However, in practical applications, because only one detection optical cable is used to monitor the bolts, only one state of data can be obtained at any given time. Before the bolt loosens, a normal curve is obtained; after the bolt loosens, this normal curve simultaneously becomes an abnormal curve. Real-time comparison is not possible; the abnormal curve can only be compared with the previously saved normal curve. This time difference can easily lead to inaccurate measurement results. Furthermore, the system needs to periodically save the measured curves, resulting in a large data volume and cumbersome operation. Summary of the Invention

[0005] The purpose of this invention is to provide an online monitoring system and method for bolts in wind turbine generator sets to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An online bolt monitoring system for wind turbine generator sets includes:

[0008] The detection module includes two parallel first detection optical cables, a second detection optical cable, and a light source. The second detection optical cable is fixedly connected to the side of the bolts of the wind turbine generator set. A first optical circulator and a second optical circulator are respectively set between the light source and the first and second detection optical cables. The light signal generated by the light source is incident on the first and second detection optical cables through the first and second optical circulators to form incident light signals, and the incident time of the incident light signals is sent to the signal processing module.

[0009] The sensor module includes a first optical fiber sensor and a second optical fiber sensor, which are respectively connected to a first optical circulator and a second optical circulator, and are used to measure the incident light signal after Rayleigh scattering inside the first detection optical cable and the second detection optical cable, as well as the return time of the Rayleigh scattering light signal.

[0010] The A / D conversion module is electrically connected to the first fiber optic sensor and the second fiber optic sensor, and is used to convert the analog quantities measured by the first fiber optic sensor and the second fiber optic sensor into digital quantities and send them to the signal processing module.

[0011] A temperature calibration module includes a temperature sensor for detecting the end temperatures of the first and second detection optical cables and a calibration unit. The calibration unit generates a temperature calibration coefficient based on the temperature measured by the temperature sensor and sends it to the signal processing module.

[0012] The signal processing module calibrates the Rayleigh scattering optical signals inside the first and second detection optical cables according to the temperature calibration coefficient, and calculates the difference signal strength and transmission time after calibration.

[0013] A network communication module, which is electrically connected to the signal processing module, is used to send the calibrated difference signal to the monitoring platform;

[0014] The monitoring platform is connected to a network communication module and is used to determine whether the bolts are loose based on the difference signal, and to locate the loose bolts.

[0015] Preferably, the formula for calculating the temperature calibration coefficient is:

[0016]

[0017] In the formula, α represents the temperature calibration coefficient, c1 represents the end temperature of the first detection optical cable, c2 represents the end temperature of the second detection optical cable, and c represents the preset reference temperature.

[0018] Preferably, the formula for calculating the difference signal strength is:

[0019] △I=αI2-αI1=α(I2-I1)

[0020] In the formula, ΔI represents the difference signal strength, I1 represents the total light intensity in the first detection optical cable, I2 represents the total light intensity in the second detection optical cable, and α represents the temperature calibration coefficient.

[0021] Preferably, the formula for calculating the transmission time of the difference signal is:

[0022] △t=T2-T1

[0023] In the formula, Δt represents the transmission time of the difference signal, T2 represents the return time of the Rayleigh scattered light signal, and T1 represents the incident time of the light signal.

[0024] Preferably, the formula used by the monitoring platform 7 for positioning is:

[0025]

[0026] In the formula, L represents the distance between the loosened bolt and the ends of the first and second detection optical cables, C represents the speed of light in vacuum, and n represents the refractive index of the optical fiber.

[0027] Preferably, a threshold β is set for the difference signal △I, and the difference signal △I is compared with the threshold β. If the difference signal △I is greater than or equal to the threshold β, the monitoring platform determines that the bolt is loose and locates it. If the difference signal △I is less than the threshold β, the monitoring platform determines that the bolt is not loose.

[0028] The present invention also provides an online monitoring method for bolts in wind turbine generator sets, wherein the method is applicable to the aforementioned monitoring system, and the specific steps include:

[0029] S1: The light source emits two identical pulsed light beams, which propagate through the first and second optical circulators respectively into the first and second detection optical cables. During propagation within the first and second detection optical cables, the two pulsed light beams undergo backscattering by Rayleigh and are detected by the first and second fiber optic sensors respectively, yielding the total light intensity I1 within the first detection optical cable and the total light intensity I2 within the second detection optical cable.

[0030] I1=i1+γ

[0031] I2=i2+γ

[0032] In the formula, i1 and i2 represent the back Rayleigh scattering intensity in the first and second detection optical cables, respectively, and γ represents the intensity of the interference light.

[0033] S2: The temperature sensor in the temperature calibration module detects the end temperatures of the first and second detection optical cables and sends the data to the calibration unit. The calibration unit uses a preset reference temperature to calculate the temperature calibration coefficient α and sends the temperature calibration coefficient α to the signal processing module. The formula for calculating the temperature calibration coefficient α is:

[0034]

[0035] In the formula, c1 represents the end temperature of the first detection optical cable, c2 represents the end temperature of the second detection optical cable, and c represents the preset reference temperature.

[0036] S3: The optical signals I1 and I2 detected by the first and second fiber optic sensors are converted into digital signals by the A / D conversion module and then sent to the signal processing module. The signal processing module calibrates I1 and I2 according to the temperature calibration coefficient α and calculates the difference signal strength ΔI after calibration. The formula for calculating the difference signal strength ΔI is:

[0037] △I=αI2-αI1=α(I2-I1)=α(i2-i1)

[0038] S4: The signal processing module calculates the transmission time Δt of the Rayleigh scattering light signal and sends it to the monitoring platform via the network communication module. The formula for calculating the transmission time Δt of the difference signal is:

[0039] △t=T2-T1

[0040] In the formula, T2 represents the return time of the Rayleigh scattered light signal, and T1 represents the incident time of the light signal.

[0041] S5: The signal processing module sends the difference signal △I to the monitoring platform via the network communication module. The monitoring platform aligns the horizontal axis with the transmission time △t of the difference signal △I in the form of distance L, and the vertical axis represents the intensity of the difference signal △I, which is displayed on the screen. This allows the round-trip time of the optical pulse to be converted into fiber length on the horizontal axis, thereby generating and monitoring the variation curve of the difference signal △I. When a bolt becomes loose, its location can be determined based on the fluctuations in the curve. The formula for calculating the relationship between distance L and the transmission time △t of the difference signal △I is as follows:

[0042]

[0043] In the formula, C represents the speed of light in a vacuum, and n represents the refractive index of the optical fiber.

[0044] Compared with the prior art, the beneficial effects of the present invention are:

[0045] This invention, by installing a first detection optical cable on the wind turbine generator body and a second detection optical cable on the turbine generator bolts, utilizes the signal collected by the first detection optical cable as a reference. This not only reduces measurement errors caused by internal interference signals within the optical fibers but also allows for real-time comparison of the signals from the second and first detection optical cables, resulting in immediate measurement results. This eliminates the need for the system to periodically save and compare data over time, simplifying the calculation method, improving system response efficiency, and enhancing test accuracy. Furthermore, by incorporating a temperature calibration module and establishing a temperature calibration coefficient α, this invention corrects the data collected by both the first and second detection optical cables, reducing the impact of temperature variations on the optical cables and test results, further improving the accuracy of the test results. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the overall system structure of the present invention;

[0047] Figure 2 This is a schematic diagram of the detection module of the present invention;

[0048] Figure 3 This is a schematic diagram showing the positions of the first and second detection optical cables.

[0049] Figure 4 This is a schematic diagram of the monitoring method of the present invention.

[0050] In the diagram: Detection module 1, Sensor module 2, A / D conversion module 3, Temperature calibration module 4, Signal processing module 5, Network communication module 6, Monitoring platform 7. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0052] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0053] Example:

[0054] Please see Figures 1 to 3 The present invention provides a technical solution:

[0055] An online bolt monitoring system for wind turbine generator sets includes:

[0056] The detection module 1 includes two parallel-arranged first detection optical cables, a second detection optical cable, and a light source. The first detection optical cable is fixedly connected to the surface of the wind turbine generator body, and the second detection optical cable is fixedly connected to the side of the bolts of the wind turbine generator body. Since the first detection optical cable is set on the surface of the wind turbine generator body, and the wind turbine generator body does not undergo significant deformation under normal conditions, the signal in the first detection optical cable is relatively stable and can be used as a reference for the signal in the second detection optical cable. A first optical circulator and a second optical circulator are respectively set between the light source and the first and second detection optical cables. The light signal generated by the light source is incident on the first and second detection optical cables through the first and second optical circulators to form incident light signals, and the incident time T1 of the light signal is sent to the signal processing module 5. The light source adopts an ECL series fiber laser, and the first and second optical circulators adopt PIOC3 series three-port optical circulators.

[0057] Sensor module 2 includes a first optical fiber sensor and a second optical fiber sensor. The first and second optical fiber sensors are isolated from each other to avoid mutual interference between the collected signals. The first and second optical fiber sensors are respectively connected to a first optical circulator and a second optical circulator, and are used to measure the intensity I1 and I2 of the incident light signal after Rayleigh scattering inside the first and second detection optical cables, as well as the return time T2 of the Rayleigh scattering light signal. The first and second optical fiber sensors use optical fiber extenders to extend the measurement range to a greater distance, so as to perform more comprehensive and accurate measurements on taller wind turbine generators.

[0058] A / D conversion module 3 is electrically connected to the first fiber optic sensor and the second fiber optic sensor. It is used to convert the analog quantities measured by the first fiber optic sensor and the second fiber optic sensor into digital quantities and send them to the signal processing module 5. The A / D conversion module 3 is based on the A / D conversion chip AD7606.

[0059] Temperature calibration module 4 includes a temperature sensor for detecting the end temperatures of the first and second detection optical cables and a calibration unit. The calibration unit generates a temperature calibration coefficient based on the temperature measured by the temperature sensor and sends it to the signal processing module. The temperature sensor is a PT100 model. The calibration unit uses an STM32F429 series chip core processor and controller to acquire temperature signals and calculate the temperature calibration coefficient α. The calculation formula is as follows:

[0060]

[0061] Signal processing module 5, also based on the STM32F429 series chip core processor and controller, and an operational amplifier circuit designed based on the OP07CDR chip, is used to calibrate the Rayleigh scattering optical signals inside the first and second detection optical cables according to the temperature calibration coefficient α, and to record the incident time and return time of the optical signals, thereby calculating the calibrated difference signal strength ΔI and the difference signal transmission time Δt. The formula for calculating the difference signal strength ΔI is:

[0062] △I=αI2-αI1=α(I2-I1)=α(i2-i1)

[0063] The formula for calculating the transmission time Δt of the difference signal is:

[0064] △t=T2-T1

[0065] In the formula, T2 represents the return time of the Rayleigh scattered light signal, and T1 represents the incident time of the light signal.

[0066] The network communication module 6 is electrically connected to the signal processing module 5. The network communication module 6 is based on the MODEM F2X03 and has the function of wireless data transmission. It is used to send the calibrated difference signal to the monitoring platform 7.

[0067] Monitoring platform 7, which is a PC, is connected to network communication module 6. The horizontal axis corresponds to the transmission time sequence of the difference signal ΔI in the form of distance, and the vertical axis represents the intensity of the difference signal ΔI in dB and is displayed on the screen, thus forming a curve showing the change of the difference signal ΔI. This curve is used to determine whether the bolt is loose. The formula for calculating the relationship between distance L and the transmission time Δt of the difference signal ΔI is as follows:

[0068]

[0069] In the formula, C represents the speed of light in a vacuum, and n represents the refractive index of the optical fiber.

[0070] A threshold β is set for the difference signal △I, and the difference signal △I is compared with the threshold β. If the difference signal △I is greater than or equal to the threshold β, the monitoring platform 7 determines that the bolt is loose and locates it. If the difference signal △I is less than the threshold β, the monitoring platform 7 determines that the bolt is not loose.

[0071] The present invention also provides an online monitoring method for bolts in wind turbine generator sets, wherein the method is applicable to the aforementioned monitoring system, and the specific steps include:

[0072] S1: The light source emits two identical pulsed light beams, which propagate through the first and second optical circulators respectively into the first and second detection optical cables. During propagation within the first and second detection optical cables, the two pulsed light beams undergo backscattering by Rayleigh and are detected by the first and second fiber optic sensors respectively, yielding the total light intensity I1 within the first detection optical cable and the total light intensity I2 within the second detection optical cable.

[0073] I1=i1+γ

[0074] I2=i2+γ

[0075] In the formula, i1 and i2 represent the back Rayleigh scattering intensity in the first and second detection optical cables, respectively, and γ represents the intensity of the interference light.

[0076] S2: The temperature sensor in temperature calibration module 4 detects the end temperatures of the first and second detection optical cables and sends the data to the calibration unit. The calibration unit uses a preset reference temperature to calculate the temperature calibration coefficient α and sends the temperature calibration coefficient α to signal processing module 5. The formula for calculating the temperature calibration coefficient α is:

[0077]

[0078] In the formula, c1 represents the end temperature of the first detection optical cable, c2 represents the end temperature of the second detection optical cable, and c represents the preset reference temperature.

[0079] S3: The optical signals I1 and I2 detected by the first and second fiber optic sensors are converted into digital signals by the A / D conversion module 3 and then sent to the signal processing module 5. The signal processing module 5 calibrates I1 and I2 according to the temperature calibration coefficient α and calculates the difference signal strength ΔI after calibration. The formula for calculating the difference signal strength ΔI is:

[0080] △I=αI2-αI1=α(I2-I1)=α(i2-i1)

[0081] S4: Signal processing module 5 calculates the transmission time Δt of the Rayleigh scattering light signal and sends it to monitoring platform 7 via network communication module 6. The formula for calculating the transmission time Δt of the difference signal is:

[0082] △t=T2-T1

[0083] In the formula, T2 represents the return time of the Rayleigh scattered light signal, and T1 represents the incident time of the light signal.

[0084] S5: Signal processing module 5 sends the difference signal △I to monitoring platform 7 via network communication module 6. Monitoring platform 7 aligns the horizontal axis with the transmission time △t of the difference signal △I in the form of distance L, and the vertical axis represents the intensity of the difference signal △I and displays it on the screen. This allows the round-trip time of the optical pulse to be converted into a scale of fiber length on the horizontal axis, thereby generating and monitoring the variation curve of the difference signal △I. When a bolt becomes loose, its location can be determined based on the fluctuations in the curve. The formula for calculating the relationship between distance L and the transmission time △t of the difference signal △I is:

[0085]

[0086] In the formula, C represents the speed of light in a vacuum, and n represents the refractive index of the optical fiber.

[0087] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0088] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0089] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. An online bolt monitoring system for wind turbine generator sets, characterized in that, include: The detection module (1) includes two parallel first detection optical cables, a second detection optical cable, and a light source. The second detection optical cable is fixedly connected to the side of the bolt of the wind turbine generator set. A first optical circulator and a second optical circulator are respectively set between the light source and the first and second detection optical cables. The light signal generated by the light source is incident on the first and second detection optical cables through the first and second optical circulators to form incident light signals. The incident time of the incident light signal is sent to the signal processing module (5). The sensor module (2) includes a first optical fiber sensor and a second optical fiber sensor. The first optical fiber sensor and the second optical fiber sensor are respectively connected to the first optical circulator and the second optical circulator, and are respectively used to measure the incident light signal after Rayleigh scattering inside the first detection optical cable and the second detection optical cable, as well as the return time of the Rayleigh scattering light signal. A / D conversion module (3), which is electrically connected to the first fiber optic sensor and the second fiber optic sensor, is used to convert the analog quantities measured by the first fiber optic sensor and the second fiber optic sensor into digital quantities and send them to the signal processing module (5). Temperature calibration module (4) includes a temperature sensor and a calibration unit for detecting the end temperature of the first detection optical cable and the second detection optical cable. The calibration unit generates a temperature calibration coefficient based on the temperature measured by the temperature sensor and sends it to the signal processing module (5). The signal processing module (5) calibrates the Rayleigh scattering light signals inside the first and second detection optical cables according to the temperature calibration coefficient, and calculates the difference signal strength and transmission time after calibration. The network communication module (6) is electrically connected to the signal processing module (5) and is used to send the calibrated difference signal to the monitoring platform (7). The monitoring platform (7) is connected to the network communication module (6) for judging whether the bolt is loose based on the difference signal, and locating the loose bolt.

2. The online bolt monitoring system for a wind turbine generator set according to claim 1, characterized in that: The formula for calculating the temperature calibration coefficient is as follows: In the formula, α represents the temperature calibration coefficient, c1 represents the end temperature of the first detection optical cable, c2 represents the end temperature of the second detection optical cable, and c represents the preset reference temperature.

3. The online bolt monitoring system for a wind turbine generator set according to claim 1, characterized in that: The formula for calculating the difference signal strength is: In the formula, ΔI represents the difference signal strength, I1 represents the total light intensity in the first detection optical cable, I2 represents the total light intensity in the second detection optical cable, and α represents the temperature calibration coefficient.

4. The online bolt monitoring system for a wind turbine generator set according to claim 1, characterized in that: The formula for calculating the transmission time of the difference signal is: In the formula, Δt represents the transmission time of the difference signal, T2 represents the return time of the Rayleigh scattered light signal, and T1 represents the incident time of the light signal.

5. The online bolt monitoring system for a wind turbine generator set according to claim 1, characterized in that: The formula used by the monitoring platform (7) for positioning is: In the formula, L represents the distance between the loosened bolt and the ends of the first and second detection optical cables, C represents the speed of light in vacuum, and n represents the refractive index of the optical fiber.

6. The online bolt monitoring system for a wind turbine generator set according to claim 1, characterized in that: A threshold β is set for the difference signal △I, and the difference signal △I is compared with the threshold β. If the difference signal △I is greater than or equal to the threshold β, the monitoring platform (7) determines that the bolt is loose and locates it. If the difference signal △I is less than the threshold β, the monitoring platform (7) determines that the bolt is not loose.

7. A method for online monitoring of bolts in a wind turbine generator set, characterized in that: The method is applicable to the monitoring system according to any one of claims 1-6, and the specific steps include: S1: The light source emits two identical pulsed light beams, which propagate through the first and second optical circulators respectively into the first and second detection optical cables. During propagation within the first and second detection optical cables, the two pulsed light beams undergo backscattering by Rayleigh and are detected by the first and second fiber optic sensors respectively, yielding the total light intensity I1 within the first detection optical cable and the total light intensity I2 within the second detection optical cable. In the formula, i1 and i2 represent the back Rayleigh scattering intensity in the first and second detection optical cables, respectively, and γ represents the intensity of the interference light. S2: The temperature sensor in the temperature calibration module (4) detects the end temperatures of the first and second detection optical cables and sends the data to the calibration unit. The calibration unit uses a preset reference temperature to calculate the temperature calibration coefficient α and sends the temperature calibration coefficient α to the signal processing module (5). The formula for calculating the temperature calibration coefficient α is: In the formula, c1 represents the end temperature of the first detection optical cable, c2 represents the end temperature of the second detection optical cable, and c represents the preset reference temperature. S3: The optical signals I1 and I2 detected by the first and second fiber optic sensors are converted into digital signals by the A / D conversion module (3) and then sent to the signal processing module (5). The signal processing module (5) calibrates I1 and I2 according to the temperature calibration coefficient α and calculates the difference signal strength ΔI after calibration. The formula for calculating the difference signal strength ΔI is: S4: Transmission time of Rayleigh scattering light signal by signal processing module (5) The calculation is performed and sent to the monitoring platform (7) via the network communication module (6). The transmission time of the difference signal is... The calculation formula is: In the formula, T2 represents the return time of the Rayleigh scattered light signal, and T1 represents the incident time of the light signal; S5: The signal processing module (5) sends the difference signal △I to the monitoring platform (7) through the network communication module (6). The monitoring platform (7) makes the horizontal axis correspond to the transmission time △t of the difference signal △I in the form of distance L, and makes the vertical axis represent the intensity of the difference signal △I and display it on the screen. In this way, the round-trip time of the optical pulse can be converted into the scale of the fiber length on the horizontal axis, thereby generating the change curve of the difference signal △I and monitoring it. When the bolt is loose, it can be located according to the fluctuation of the curve. The calculation formula between the distance L and the transmission time △t of the difference signal △I is: In the formula, C represents the speed of light in a vacuum, and n represents the refractive index of the optical fiber.

Images