Wind turbine with turbine blade strain control
By integrating an electric time-domain reflectometry device and an electrical path into wind turbine blades, the complex and inaccurate strain measurement problem in existing technologies is solved, enabling inexpensive and high-precision strain control and damage detection, and supporting the optimization of wind turbine operation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-26
- Publication Date
- 2026-03-27
AI Technical Summary
Existing wind turbine blade strain measurement systems are complex and can only be executed during idle time, lacking accuracy and unable to reliably detect damage to minute structures.
An electric time domain reflection device is integrated into a wind turbine blade. The strain and damage level are determined by measuring the electric time domain reflection through the first and second electric paths. The spar cap is used as the electric path and combined with the lightning protection system to achieve inexpensive and high-precision strain control.
It enables high-precision strain measurement and damage detection during wind turbine operation, reduces equipment costs, improves reliability and accuracy, supports wind turbine operation control, and avoids damage.
Smart Images
Figure CN121752811A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a wind turbine with strain control for wind turbine blades. The invention also relates to a method for determining the strain of wind turbine blades. Background Technology
[0002] Wind turbine blades, especially those of offshore wind turbines, are subjected to large mechanical loads. Excessive wind loads can cause overload on the wind turbine blades, which can lead to structural damage and failure.
[0003] Therefore, obtaining information about the strain of wind turbine blades is crucial for the operation and maintenance of wind turbines. Distributed strain within wind turbine blades is typically measured using fiber-bragg sensors via optical time-domain reflectometry. Due to the high complexity of the measurement system required to perform this measurement, it is typically used for testing purposes, such as in a workshop or when the wind turbine is idle.
[0004] Alternatively, point measurements of the turbine blade strain have been performed using conventional strain gauges. This measurement can be performed during wind turbine operation, for example, for control purposes. These sensors used in load-optimized pitch control strategies (LOPC) are of the conventional type.
[0005] Known strain measurement systems for turbine blades have the following drawbacks: they are often very complex to set up, measurements can only be performed during the idle time of the wind turbine, or they lack accuracy, making it impossible to reliably detect minor structural damage to the turbine blades. Summary of the Invention
[0006] Therefore, the object of the present invention is to eliminate, or at least partially eliminate, the disadvantages described above in the case of wind turbines. In particular, the object of the present invention is to provide a wind turbine with wind turbine blade strain control and a method for determining the strain of the wind turbine blades, said wind turbine and said method avoiding complex measurement systems and / or ensuring accurate strain measurement during wind turbine operation in a simple and inexpensive manner, for example, point strain measurement and / or distributed strain measurement.
[0007] The aforementioned objective is achieved through the claims. Therefore, the problem is solved by a wind turbine with strain control of wind turbine blades having the features of independent claim 1, and by a method for determining the strain of wind turbine blades having the features of dependent claim 11. Further features and details of the invention become apparent from the dependent claims, the description, and the drawings. The features and details described in conjunction with the wind turbine according to the invention naturally also apply to the method according to the invention, and vice versa, so that the disclosure regarding various aspects of the invention can or always be cross-referenced.
[0008] According to a first aspect of the invention, this objective is achieved by a wind turbine with wind turbine blade strain control. The wind turbine includes a tower, nacelle, rotor, hub, a plurality of wind turbine blades, a generator, and a controller for controlling the operation of the wind turbine. The wind turbine blades include a root section for engaging the hub, a tip section, and an intermediate section between the root section and the tip section. Furthermore, the wind turbine blades include a spar-cap extending between the root section and the tip section. According to the invention, the wind turbine blades include a first electrical path from the root section to the tip section, a second electrical path from the tip section to the root section, and an electrical time-domain reflectometry device electrically connected to the first and second electrical paths for performing electrical time-domain reflectometry measurements within the first and second electrical paths.
[0009] The wind turbine according to the present invention may include a plurality of different components, which may be of conventional size, shape and / or material. In other words, when viewed from the outside, the wind turbine may not necessarily have an appearance different from that of a conventional wind turbine.
[0010] The wind turbine blade includes a root section for securing the wind turbine blade to the hub (e.g., a pitch bearing secured to the hub). Preferably, the root section has a circular or elliptical cross-section and a root flange with a plurality of mounting holes for securing the wind turbine blade to the hub (e.g., by bolts and nuts).
[0011] Adjacent to the root section, the wind turbine blade includes the intermediate section. The intermediate section constitutes the longest section of the wind turbine blade. Preferably, the intermediate section has a flat or substantially flat shape. More preferably, the intermediate section is twisted about its longitudinal axis. Preferably, the width of the intermediate section decreases from the root section toward the tip section.
[0012] Adjacent to the intermediate section, the wind turbine blade includes the tip section. The tip section forms the distal end of the wind turbine blade relative to the hub. The tip section may include a lightning rod projecting from the tip section, for example, in a direction away from the root section, for example, parallel to or substantially parallel to the longitudinal axis of the wind turbine blade.
[0013] The spar cap extends between the root section and the tip section. Preferably, the spar cap extends over the entire intermediate section. More preferably, the spar cap extends into the root section and / or the tip section. The spar cap is configured to provide stability to the wind turbine blade. Preferably, the spar cap forms part of the outer surface of the wind turbine blade. Preferably, the wind turbine blade includes two spar caps spaced apart and connected to each other by a shear web.
[0014] The first and second electrical paths are made of conductive materials, such as copper, aluminum, and carbon fiber. The conductive material can be integrated into the wind turbine blade wall material or attached to the inner surface of the wind turbine blade wall, for example, through adhesives, resins, coatings, etc. Preferably, the conductive material is configured to withstand current from lightning strikes and transmit the current from the tip section to the root section. Therefore, it is preferable that the first and / or second electrical paths are part of the lightning protection system of the turbine blade. Preferably, the conductive material can be in or at the spar cap.
[0015] Preferably, the first electrical path and the second electrical path are electrically connected at or near the tip section. Therefore, the first electrical path and the second electrical path constitute a circuit extending from the root section to the tip section and returning to the root section.
[0016] The electrical time-domain reflectometry (ETDAR) device is electrically connected to the first electrical path and / or the second electrical path. Preferably, the ETDAR device is located within the wind turbine blade, the hub, or the nacelle. The ETDAR device is configured to perform ETDAR measurements within the first and second electrical paths. This can be performed, for example, by sending electrical pulses through the first electrical path and receiving electrical pulses from the second electrical path. By evaluating the runtime of the electrical pulses, parameter modifications, etc., the ETDAR device can determine the degree and distribution of strain and damage to the wind turbine blade with high accuracy. Therefore, strain control of the wind turbine blade can be performed. In this invention, strain control can be considered as strain measurement. Advantageously, strain control includes measures to keep the strain below a strain threshold. The controlled strain can be distributed strain and / or point strain.
[0017] The wind turbine according to the present invention has the advantage over conventional wind turbines in that the degree and distribution of strain and damage to the wind turbine blades can be reliably determined with high accuracy in a simple and inexpensive manner. Even existing wind turbines can be easily equipped with strain control. Furthermore, expensive equipment can be saved. Moreover, the strain can be controlled both during wind turbine operation and in inactive states. Therefore, the determined strain data can be used to support the operational control of the wind turbine, for example, to avoid damage to the wind turbine due to strong winds, and to determine cracks, delamination, fractures, or other damage within the structure of the wind turbine blades.
[0018] According to a preferred further extension of the invention, the wind turbine may be configured such that the first electrical path and / or the second electrical path are provided by a sparsity cap of the wind turbine blade. Preferably, the first electrical path is provided by a first sparsity cap of the wind turbine blade, and the second electrical path is provided by a second sparsity cap of the wind turbine blade, wherein the first and second sparsity caps are electrically connected at the tip section. Alternatively, the first electrical path is provided by a first section of the sparsity cap of the wind turbine blade, and the second electrical path is provided by a second section of the sparsity cap, wherein the first and second sections are electrically connected at the tip section. For a sparsity cap with carbon fibers, the carbon fibers can form the electrical path. Thus, a circuit is provided for the electrical time-domain reflectometry measurement. This has the advantage of providing a simple and inexpensive way to improve the integration of strain control into existing wind turbine blades. Furthermore, since the electrical path is integrated into the sparsity cap, damage to the sparsity cap (a critical structure of the wind turbine blade) can be determined with high reliability and accuracy.
[0019] According to the present invention, the spar cap preferably comprises carbon fiber. More preferably, the spar cap comprises a plurality of carbon fibers, carbon fiber plates, etc. More preferably, the carbon fibers are impregnated with resin. Preferably, the spar cap is manufactured as fiber-reinforced plastic or fiber-reinforced polymer, wherein the reinforcing fibers are carbon fibers or at least comprise carbon fibers. This has the advantage of providing a simple and inexpensive way to improve the integration of strain control into existing wind turbine blades. Furthermore, by integrating the electrical path into the spar cap, damage to the spar cap (a critical structure of the wind turbine blade) can be determined with high reliability and accuracy.
[0020] More preferably, the first electrical path is provided by a first electrical conductor attached to a first wall of the wind turbine blade, and / or the second electrical path is provided by a second electrical conductor attached to a second wall of the wind turbine blade. The first and / or second electrical conductors may be attached to the spar cap, particularly on the side facing the interior of the wind turbine blade, for example, adjacent to the shear web. The first and / or second electrical conductors may be configured as wires, etc. The material of the conductors may be metal, such as copper, aluminum, etc. Alternatively, the material of the conductors may be carbon, for example, in the form of fiber bundles, fiberboard, etc. The fibers may be laminated to the spar cap, for example, by resin, plastic, etc. This has the advantage of providing the first and second electrical paths in a simple and inexpensive manner.
[0021] In a particularly preferred embodiment of the invention, the first electrical conductor and / or the second electrical conductor are configured as a metal strip. The metal strip may also be referred to as a "metal strip" or "metal bar." Preferably, the length of the metal strip from the root section to the tip section is substantially greater than the width of the metal strip. More preferably, the width of the metal strip is substantially greater than the thickness of the metal strip. The preferred metal is copper, or alternatively, aluminum. Preferably, the metal strip is glued to the inner surface of the wind turbine blade, for example, glued to the spar cap. This has the advantage of enabling reliable inspection of the condition of a relatively large area of the wind turbine blade regarding strain, cracks, or other damage in a simple and inexpensive manner.
[0022] Preferably, the electrical time-domain reflectometry device is electrically connected to the lightning protection system of the wind turbine blade. The lightning protection system extends from the tip section to the root section and is connected to ground, preferably passing through or adjacent to the wind turbine tower. By using the lightning protection system for strain measurement, the electrical conductors of the lightning system perform at least two different tasks for the wind turbine. This has the advantage of using the wind turbine's resources very efficiently in a simple and inexpensive manner.
[0023] According to a preferred embodiment of the invention, the controller is configured to analyze the test signal response of the electrical time-domain reflectometry device and operate the wind turbine based on the analysis. The parameters of the wind turbine that can be controlled in this regard may include the pitch angle, yaw angle, flap angle, generator torque, stall device actuation, etc., of the wind turbine blades. Therefore, for example, data on the strain within the wind turbine blades due to strong winds and a first pitch angle of the wind turbine blades can be used by the controller to change the first pitch angle to a second pitch angle when the strain is higher than a predetermined upper strain threshold, for which the wind turbine blades are less exposed to wind, or to change the first pitch angle to a third pitch angle when the strain is lower than a predetermined lower strain threshold, for which the wind turbine blades are more exposed to wind. This has the advantage of reducing the risk of damage to the wind turbine blades due to overload in a simple and inexpensive manner, and improving the power generation of the wind turbine.
[0024] Particularly preferably, the analysis preparation for the test signal response includes comparing the actual test signal response with a previous test signal response of the same wind turbine blade, and / or comparing the actual test signal response of a first wind turbine blade with the actual test signal response of a second wind turbine blade, and / or applying the test signal response to a computer model of the wind turbine blade. Preferably, other variables (such as wind speed, precipitation, pitch angle, yaw angle, etc.) are considered in the analysis. By comparing the actual test signal response for the wind turbine blade with a previous test signal response, structural changes in the wind turbine blade, such as those due to strain, fracture, etc., can be easily and reliably identified. By comparing the actual test signal response for the first wind turbine blade with the actual test signal response for the second wind turbine blade, deviations in the response for different wind turbine blades can be determined, which is an indication of potential damage to one of these wind turbine blades, wherein the other variables mentioned above can be ignored. Using a computer model of the wind turbine blades, the state of the wind turbine blades can be reliably calculated. Preferably, the controller includes artificial intelligence for preparing the analysis and / or for adjusting the computer model of the wind turbine, for example, taking into account measurement data from the electrical time-domain reflectometry device, measurement data from additional sensors, etc. This has the advantage of enabling the determination of the degree and distribution of strain and damage to the wind turbine blades in a simple and inexpensive manner with improved reliability and higher accuracy.
[0025] According to a preferred embodiment of the invention, the electrical time-domain reflectometry (ETDAR) device is disposed at the root section of the wind turbine blade or at the hub. The root section of the wind turbine blade and the hub include a hollow space that provides sufficient space for the ETDAR device. The ETDAR device can be mounted, for example, to the inner side of the turbine blade wall in the root section or the inner side of the hub wall using screws, adhesive, etc. This has the advantage of enabling a compact design of the wind turbine in a simple and inexpensive manner, as no additional space is required within the nacelle boundaries for the ETDAR device.
[0026] Preferably, the wind turbine includes a lightning bypass switch for disconnecting the electrical time-domain reflectometry (ETDAR) device from the tip section and providing an electrical bypass from the tip section to the ETDAR device in a bypass position, and for providing electrical continuity from the tip section to the ETDAR device in a measurement position. Preferably, the lightning bypass switch is configured to obtain the bypass position under standard conditions, while the measurement position is obtained only during the measurement period of the ETDAR device. Using the lightning bypass switch, the ETDAR device can be protected from lightning strikes. This has the advantage of further increasing the reliability and lifespan of the ETDAR device in a simple and inexpensive manner.
[0027] According to a second aspect of the invention, this objective is achieved by a method for determining the strain of wind turbine blades in a wind turbine according to the invention. The method includes: - A test signal for the first electrical path is generated by the electrical time-domain reflectometry device. - The first test signal response is received from the first electrical path by the electrical time-domain reflectometry device. - The second test signal response received from the second electrical path by the electrical time-domain reflectometry device, and - The strain of the wind turbine blade is determined by the electrical time domain reflectometer by analyzing the response of the test signal.
[0028] First, the electrical time-domain reflectometry (OTDR) device generates a test signal passing through the first electrical path. This test signal can be a standard test signal used in standard OTDR procedures, for example, to measure the condition of underground cables. Due to the characteristics and conditions of the first and second electrical paths, the test signal can be reflected back to the OTDR device through the first electrical path. This reflection is particularly strong when the electrical path has a break. This reflection is referred to as the first test signal response.
[0029] Furthermore, due to the characteristics and conditions of the first and second electrical paths, the test signal can be transmitted to the electrical time-domain reflectometry (OTDR) device via the second electrical path. This transmission is particularly strong when the electrical path is unbroken. This transmission is referred to as the second test signal response. When the first and / or second electrical paths are interrupted, the second test signal response can be a zero signal. Finally, the OTDR device analyzes the received first and second test signal responses and determines the strain of the wind turbine blade.
[0030] The method according to the invention possesses all the advantages already described for the wind turbine according to the first aspect of the invention. Therefore, the method according to the invention has the advantage over conventional methods in that it can reliably determine the degree and distribution of strain and damage to the wind turbine blades with high accuracy in a simple and inexpensive manner. Furthermore, expensive equipment can be saved. Moreover, the strain can be controlled both during wind turbine operation and in inactive states. Therefore, the determined strain data can be used to support the operational control of the wind turbine, for example, to avoid damage to the wind turbine due to strong winds, and to determine cracks, fractures, or other damage within the structure of the wind turbine blades.
[0031] Preferably, analyzing the test signal response includes comparing the actual test signal response with a previous test signal response of the same wind turbine blade, and / or comparing the actual test signal response of a first wind turbine blade of the wind turbine blade with the actual test signal response of a second wind turbine blade of the wind turbine blade, and / or applying the test signal response to a computer model of the wind turbine blade.
[0032] Preferably, other parameters, such as wind speed, air pressure, blade pitch angle, precipitation, and temperature, are also considered to enable meaningful comparisons without significant errors. By analyzing the test signal by comparing the actual test signal response with the previous test signal response of the same wind turbine blade, variations in the characteristics of the wind turbine blade can be easily determined.
[0033] By analyzing the test signals by comparing the actual test signal response of the first wind turbine blade with that of the second wind turbine blade, it is easy to determine that a change in the characteristics of one of the two wind turbine blades has occurred. More preferably, this comparison also involves comparing the actual test signal response of the third wind turbine blade in the same manner. Therefore, all wind turbine blades are monitored, and the risk of erroneous analysis due to simultaneous damage to two wind turbine blades is reduced.
[0034] By analyzing the test signal using a computer model that applies the test signal response to the wind turbine blade, the overall state of the wind turbine blade can be accurately determined. Preferably, artificial intelligence is involved in this analysis to determine the overall state of the wind turbine blade and to adjust the computer model based on the individual characteristics of the wind turbine blade, for example, by comparing the characteristics of the wind turbine blade during the initial operation of the wind turbine. This has the advantage of further improving the analysis of the state of the wind turbine blade in a simple and inexpensive manner. Attached Figure Description
[0035] Further advantages, features, and details of the invention will become apparent from the following description, in which working examples of the invention are described in detail with reference to the accompanying drawings. Thus, the features derived from the claims and those mentioned in the specification are essential to the invention, whether used alone or in any combination. In the drawings: Figure 1 A schematic side view of a wind turbine according to a preferred embodiment of the present invention is shown. Figure 2 Show Figure 1 A schematic perspective cross-sectional view of a wind turbine blade. Figure 3 Showing the use of Figure 1 A schematic exploded view of alternative wind turbine blades for wind turbines, and Figure 4 A schematic flowchart illustrating a preferred embodiment of the method according to the present invention is shown.
[0036] Components with the same function and purpose Figures 1 to 4 Each figure is labeled with the same reference numerals. Detailed Implementation
[0037] exist Figure 1A schematic side view illustrates a wind turbine 1 according to a preferred embodiment of the present invention. The wind turbine 1 includes a tower 2, a nacelle 3 pivotally mounted to the tower 2, a rotor 4 rotatably mounted to the nacelle 3, a hub 5 mounted to one end of the rotor 4, and three wind turbine blades 6, each blade having a root section 9, a tip section 10, and an intermediate section 11 between the root section 9 and the tip section 10. The root section 9 is pivotally mounted to the hub 5.
[0038] A generator 7 is arranged inside the nacelle 3 and mechanically connected to the rotor 4 to convert the rotational energy of the rotor 4 into electrical energy. A controller 8 is arranged inside the nacelle 3 to control the operation of the wind turbine 1. An electrical time domain reflection device 15 is arranged in the root section 9 of the wind turbine blade 6 to perform electrical time domain reflection measurements within the wind turbine blade 6.
[0039] Figure 2 A schematic perspective cross-sectional view is shown. Figure 1 The wind turbine blade 6 of the wind turbine 1. Specifically for stabilization purposes, the wind turbine blade 6 includes two spar caps 12 made of carbon fiber and resin. In this figure, the upper spar cap 12 forms a first electrical path 13. The lower spar cap 12 forms a second electrical path 14.
[0040] exist Figure 3 In the middle, a schematic exploded view is shown for... Figure 1 An alternative wind turbine blade 6 for the wind turbine 1 is shown. The root section 9, middle section 11, and tip section 10 of the wind turbine blade 6 are illustrated. In this alternative embodiment, a first electrical path 13 is provided by a first electrical conductor 16. The first electrical conductor 16 is attached to a first wall 17 of the wind turbine blade 6. A second electrical path 14 is provided by a second electrical conductor 18. The second electrical conductor 18 is attached to a second wall 19 of the wind turbine blade 6.
[0041] Figure 4 A preferred embodiment of the method according to the invention is illustrated in a schematic flowchart. In a first action 100, a test signal for a first electrical path 13 is generated by an electrical time-domain reflectometry (OTDR) device 15. In a second action 200, a first test signal response from the first electrical path 13 is received by the OTDR device 15. In a third action 300, a second test signal response from the second electrical path 14 is received by the OTDR device 15. In a fourth action 400, the strain of the wind turbine blade 6 is determined by the OTDR device 15 through analysis of the test signal response.
Claims
1. A wind turbine (1) with wind turbine blade strain control, the wind turbine comprising a tower (2), a nacelle (3), a rotor (4), a hub (5), multiple wind turbine blades (6), a generator (7), and a controller (8) for controlling the operation of the wind turbine (1), wherein, The wind turbine blade (6) includes a root section (9), a tip section (10), and a middle section (11) for engaging the hub (5), the middle section being between the root section (9) and the tip section (10), wherein the wind turbine blade (6) includes a spar cap (12) extending between the root section (9) and the tip section (10), characterized in that the wind turbine blade (6) includes a first electrical path (13) and a second circuit. The wind turbine blade (6) has a first electrical path (14) from the root section (9) to the tip section (10) of the wind turbine blade (6), and a second electrical path from the tip section (10) to the root section (9). The electrical time domain reflector is electrically connected to the first electrical path (13) and the second electrical path (14) for performing electrical time domain reflectance measurements within the first electrical path (13) and the second electrical path (14).
2. The wind turbine (1) according to claim 1, characterized in that, The first electrical path (13) and / or the second electrical path (14) are provided by the spar cap (12) of the wind turbine blade (6).
3. The wind turbine (1) according to claim 2, characterized in that, The wing cap (12) comprises carbon fiber.
4. The wind turbine (1) according to any one of the preceding claims, characterized in that, The first electrical path (13) is provided by a first electrical conductor (16) attached to the first wall (17) of the wind turbine blade (6), and / or the second electrical path (14) is provided by a second electrical conductor (18) attached to the second wall (19) of the wind turbine blade (6).
5. The wind turbine (1) according to claim 4, characterized in that, The first electrical conductor (16) and / or the second electrical conductor (18) are configured as metal strips.
6. The wind turbine (1) according to any one of the preceding claims, characterized in that, The electrical time domain reflector (15) is electrically connected to the lightning protection system of the wind turbine blade (6).
7. The wind turbine (1) according to any one of the preceding claims, characterized in that, The controller (8) is configured to analyze the test signal response of the electrical time domain reflectometer (15) and control the operation of the wind turbine (1) based on the analysis.
8. The wind turbine (1) according to claim 7, characterized in that, Preparation for the analysis of the test signal response includes comparing the actual test signal response with the previous test signal response of the same wind turbine blade (6), and / or comparing the actual test signal response of the first wind turbine blade (6) of the wind turbine blade (6) with the actual test signal response of the second wind turbine blade (6) of the wind turbine blade (6), and / or applying the test signal response to a computer model of the wind turbine blade (6).
9. The wind turbine (1) according to any one of the preceding claims, characterized in that, The electrical time domain reflector (15) is arranged at the root section (9) of the wind turbine blade (6) or at the hub (5).
10. The wind turbine (1) according to any one of the preceding claims, characterized in that, The wind turbine (1) includes a lightning bypass switch for disconnecting the electrical time domain reflector (15) from the tip section (10) in the bypass position and providing an electrical bypass from the tip section (10) around the electrical time domain reflector (15), and for providing electrical conduction from the tip section (10) to the electrical time domain reflector (15) in the measurement position.
11. A method for determining the strain of a wind turbine blade (6) of a wind turbine (1) according to any one of the preceding claims, the method comprising: - A test signal for the first electrical path (13) is generated by the electrical time-domain reflectometry device (15). - The first test signal response is received from the first electrical path (13) by the electrical time-domain reflectometry device (15). - The second test signal response received by the electrical time-domain reflectometry device (15) from the second electrical path (14), and - The strain of the wind turbine blade (6) is determined by the electrical time domain reflectometer (15) by analyzing the response of the test signal.
12. The method according to claim 11, characterized in that, Analyzing the test signal response includes comparing the actual test signal response with the previous test signal response of the same wind turbine blade (6), and / or comparing the actual test signal response of the first wind turbine blade (6) of the wind turbine blade (6) with the actual test signal response of the second wind turbine blade (6) of the wind turbine blade (6), and / or applying the test signal response to a computer model of the wind turbine blade (6).