Stress monitoring device suitable for bearing part of mixed tower wind driven generator

Abstract

The invention discloses a stress monitoring device suitable for a bearing part of a mixed tower wind driven generator. The stress monitoring device comprises a far-end server, the steel-mixed tower drum is erected on a mixed tower wind driven generator foundation, the fiber bragg grating monitoring device is arranged on the steel-mixed tower drum, the stress monitoring box is arranged on the mixed tower wind driven generator foundation, the fiber bragg grating monitoring device is connected with the stress monitoring box, and the stress monitoring box is connected with the far-end server. The device can accurately monitor the stress of the tower drum.

Description

Technical Field

[0001] The invention belongs to the technical field of wind power generation, and relates to a stress monitoring device suitable for bearing components of a mixed-tower wind turbine generator. Background Art

[0002] With the rapid development of wind power generation, medium and high wind speed areas on land have been developed to the limit, while low wind speed (4.5m / s~6.5m / s) resources in the central, eastern and southern regions of my country are rich in reserves, with a developable amount of 1 billion kW·h, close to the load center of the power grid, and huge development potential. However, wind turbines in low wind speed areas require higher towers to obtain higher wind speeds and increase power generation, which forces the construction height of wind turbine towers in low wind speed areas to continue to increase. The tower height in low wind speed areas in the central, eastern and southern regions of China has climbed to 160m.

[0003] The load-bearing components of a hybrid tower wind turbine mainly include the following key parts: 1. Foundation: The foundation is the root of the wind turbine, and it must be able to support the entire wind turbine and the forces acting on it. For onshore wind turbines, the foundation is usually a large and heavy concrete structure block covered by soil on the ground. Although it is invisible, it plays a vital role. For offshore wind turbines far away from land, the foundation is also invisible underwater, but it has sufficient mass to support and maintain the weight of the wind turbine and the various forces applied to it. 2. Tower: The tower is the main load-bearing component of the wind turbine generator set. Its main function is to support the mechanical components of the wind turbine, the power generation system (gravity load), and to withstand the force of the wind rotor and the force of the wind on the tower. The tower of a hybrid tower wind turbine usually adopts a modular design, breaking through the transportation and safety bottlenecks of traditional steel towers. The height of the tower is similar to the diameter of the circle formed by the rotation of the blades of the wind turbine it carries. Generally speaking, the higher the wind turbine, the easier it is to catch high-speed wind.

[0004] The advantages of traditional steel towers are gradually being replaced by steel-concrete composite wind turbine towers. Pure steel towers are easy to manufacture, lightweight, and highly industrialized, but as flexible towers, they have low rigidity, prominent vortex-induced vibration and fatigue problems, limiting their application in low wind speed areas. The emerging steel-concrete tower consists of an upper steel cylinder section and a lower concrete section. The concrete section is usually combined with assembly technology, prefabricated and transported in layers and sections, and finally assembled on site. It has greater rigidity, strong stability, and excellent fatigue resistance, breaking through the economic height of traditional pure steel towers.

[0005] However, due to the relatively small proportion of hybrid towers in the current wind power market, manufacturing and construction units are relatively lacking in technical and management experience in the manufacturing and installation of hybrid tower units. Owners have weak risk assessment and component non-destructive testing capabilities in hybrid tower structures. Specifically, there is a lack of relevant technologies for accurately monitoring the strain of hybrid tower barrels. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art and provide a stress monitoring device suitable for bearing components of a mixed-tower wind turbine, which can accurately monitor the stress of the tower.

[0007] To achieve the above-mentioned purpose, the present invention discloses a stress monitoring device suitable for the bearing components of a hybrid tower wind turbine, including a remote server; a steel-hybrid tower is erected on the foundation of the hybrid tower wind turbine, a fiber grating monitoring device is arranged on the steel-hybrid tower, a stress monitoring box is arranged on the foundation of the hybrid tower wind turbine, the fiber grating monitoring device is connected to the stress monitoring box, and the stress monitoring box is connected to the remote server.

[0008] The further improvement of the stress monitoring device for the bearing components of the mixed tower wind turbine according to the present invention is:

[0009] The steel-concrete tower is divided from bottom to top into a first straight section of a concrete tower, a first variable-section section of a concrete tower, a second straight section of a concrete tower, a second variable-section section of a concrete tower and a straight section of a steel tower.

[0010] The fiber grating monitoring device includes a fiber grating sensor No. 1, a fiber grating sensor No. 2, a fiber grating sensor No. 3, a fiber grating sensor No. 4 and a fiber grating sensor No. 5, wherein the fiber grating sensor No. 1 is arranged on the first straight section of the concrete tower, the fiber grating sensor No. 2 is arranged on the first variable cross-section section of the concrete tower, the fiber grating sensor No. 3 is arranged on the second straight section of the concrete tower, the fiber grating sensor No. 4 is arranged on the second variable cross-section section of the concrete tower, and the fiber grating sensor No. 5 is arranged on the straight section of the steel tower;

[0011] A No. 1 fiber grating sensor, a No. 2 fiber grating sensor, a No. 3 fiber grating sensor, a No. 4 fiber grating sensor and a No. 5 fiber grating sensor are connected to the stress monitoring box.

[0012] The stress monitoring box includes a JEME-IFBG / D04 demodulator and a 4G DTU wireless communication module. The fiber grating monitoring device is connected to the JEME-IFBG / D04 demodulator, and the JEME-IFBG / D04 demodulator is connected to a remote server via the 4G DTU wireless communication module.

[0013] The output end of the JEME-IFBG / D04 demodulator is a USB interface, and the input end of the 4G DTU wireless communication module is a VGA interface.

[0014] The fiber grating monitoring device is fixed on the outer wall of the steel-concrete tower by screws and wire nails.

[0015] The stress monitoring box is fixed to the foundation of the mixed tower wind turbine by anchor screws.

[0016] A wind turbine box is arranged on the top of the straight section of the steel tower tube, a wind turbine is arranged in the wind turbine box, and a driving shaft of the wind turbine is connected with a blade connecting component after passing through the wind turbine box.

[0017] The stress monitoring device for the bearing components of a hybrid tower wind turbine of the present invention comprises a remote server; a steel-hybrid tower is erected on the foundation of the hybrid tower wind turbine, a fiber grating monitoring device is arranged on the steel-hybrid tower, a stress monitoring box is arranged on the foundation of the hybrid tower wind turbine, the fiber grating monitoring device is connected to the stress monitoring box, and the stress monitoring box is connected to the remote server;

[0018] The steel-concrete tower is divided from bottom to top into a first straight section of the concrete tower, a first variable cross-section section of the concrete tower, a second straight section of the concrete tower, a second variable cross-section section of the concrete tower and a straight section of the steel tower;

[0019] A wind turbine box is arranged on the top of the straight section of the steel tower tube, a wind turbine is arranged in the wind turbine box, and a driving shaft of the wind turbine is connected with a blade connecting component after passing through the wind turbine box.

[0020] The further improvement of the stress monitoring device for the bearing components of the mixed tower wind turbine according to the present invention is:

[0021] The fiber grating monitoring device includes a fiber grating sensor No. 1, a fiber grating sensor No. 2, a fiber grating sensor No. 3, a fiber grating sensor No. 4 and a fiber grating sensor No. 5, wherein the fiber grating sensor No. 1 is arranged on the first straight section of the concrete tower, the fiber grating sensor No. 2 is arranged on the first variable cross-section section of the concrete tower, the fiber grating sensor No. 3 is arranged on the second straight section of the concrete tower, the fiber grating sensor No. 4 is arranged on the second variable cross-section section of the concrete tower, and the fiber grating sensor No. 5 is arranged on the straight section of the steel tower;

[0022] A No. 1 fiber grating sensor, a No. 2 fiber grating sensor, a No. 3 fiber grating sensor, a No. 4 fiber grating sensor and a No. 5 fiber grating sensor are connected to the stress monitoring box.

[0023] The present invention has the following beneficial effects:

[0024] In the specific operation of the stress monitoring device for the bearing components of a hybrid tower wind turbine described in the present invention, a fiber grating monitoring device is arranged on the steel-hybrid tower, and the strain information detected by the fiber grating monitoring device is sent to a remote server via a stress monitoring box to realize accurate monitoring of the stress of the tower. It should be noted that the fiber grating monitoring device has the advantages of anti-electromagnetic interference, small size (standard bare optical fiber is 125μm), light weight, good temperature resistance (the upper limit of the operating temperature can reach 400℃~600℃), strong multiplexing capability, long transmission distance, corrosion resistance, high sensitivity, passive device, easy deformation and high precision.

[0025] Furthermore, in the present invention, the fiber grating sensors are arranged in sections, which can realize accurate monitoring of the strain of the steel-concrete tower, capture the strain changes in different positions and directions, and provide a data basis for subsequent structural health status assessment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural diagram of the present invention;

[0027] Figure 2 It is the principle diagram of the present invention;

[0028] Figure 3 This is a fixed structure diagram of the fiber grating sensor in the present invention.

[0029] Among them, 1 is the foundation of the mixed tower wind turbine, 2 is the first straight section of the concrete tower, 3 is the first variable-section section of the concrete tower, 4 is the second straight section of the concrete tower, 5 is the second variable-section section of the concrete tower, 6 is the straight section of the steel tower, 7 is the wind turbine box, 8 is the blade connecting component, 9 is the No. 5 fiber grating sensor, 10 is the No. 4 fiber grating sensor, 11 is the No. 3 fiber grating sensor, 12 is the No. 2 fiber grating sensor, 13 is the No. 1 fiber grating sensor, 14 is the stress monitoring box, 15 is the fiber grating monitoring device, 16 is the JEME-IFBG / D04 demodulator, 17 is the 4G DTU wireless communication module, 18 is the remote server, 19 is the wire nail, and 20 is the screw. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In the description of the present invention, it should be understood that the terms “include” and “comprises” indicate the presence of described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0032] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0033] It should be further understood that the term "and / or" used in the present specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects are in an "or" relationship.

[0034] It should be understood that, although the terms first, second, third, etc. may be used to describe preset ranges, etc. in the embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are only used to distinguish preset ranges from each other. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0035] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0038] Embodiment 1

[0039] refer to Figure 1The stress monitoring device for the bearing components of a mixed tower wind turbine according to the present invention comprises a remote server 18; a steel-concrete tower is erected on a mixed tower wind turbine foundation 1, a fiber grating monitoring device 15 is arranged on the steel-concrete tower, a stress monitoring box 14 is arranged on the mixed tower wind turbine foundation 1, the fiber grating monitoring device 15 is connected to the stress monitoring box 14, and the stress monitoring box 14 is connected to the remote server 18; the steel-concrete tower is divided from bottom to top into a first straight section 2 of a concrete tower, a first variable section 3 of a concrete tower, a second straight section 4 of a concrete tower, a second variable section 5 of a concrete tower and a straight section 6 of a steel tower; a wind turbine box 7 is arranged on the top of the straight section 6 of the steel tower, a wind turbine box 7 is arranged in the wind turbine box 7, and a blade connecting component 8 is connected to the driving shaft of the wind turbine after passing through the wind turbine box 7. The fiber grating monitoring device 15 includes a fiber grating sensor No. 1 13, a fiber grating sensor No. 2 12, a fiber grating sensor No. 3 11, a fiber grating sensor No. 4 10 and a fiber grating sensor No. 5 9, wherein the fiber grating sensor No. 1 13 is arranged on the first straight section 2 of the concrete tower, the fiber grating sensor No. 2 12 is arranged on the first variable cross-section section 3 of the concrete tower, the fiber grating sensor No. 3 11 is arranged on the second straight section 4 of the concrete tower, the fiber grating sensor No. 4 10 is arranged on the second variable cross-section section 5 of the concrete tower, and the fiber grating sensor No. 5 9 is arranged on the straight section 6 of the steel tower; the fiber grating sensor No. 1 13, the fiber grating sensor No. 2 12, the fiber grating sensor No. 3 11, the fiber grating sensor No. 4 10 and the fiber grating sensor No. 5 9 are connected to the stress monitoring box 14.

[0040] Embodiment 2

[0041] refer to Figure 1 The stress monitoring device for the bearing components of a mixed tower wind turbine described in the present invention comprises a remote server 18, a steel-concrete tower is erected on a mixed tower wind turbine foundation 1, and the steel-concrete tower is divided from bottom to top into a first straight section 2 of a concrete tower, a first variable section section 3 of a concrete tower, a second straight section 4 of a concrete tower, a second variable section section 5 of a concrete tower and a straight section 6 of a steel tower, wherein a No. 1 fiber grating sensor 13 is arranged on the first straight section 2 of the concrete tower, a No. 2 fiber grating sensor 12 is arranged on the first variable section section 3 of the concrete tower, a No. 3 fiber grating sensor 11 is arranged on the second straight section 4 of the concrete tower, a No. 4 fiber grating sensor 10 is arranged on the second variable section section 5 of the concrete tower, and a No. 5 fiber grating sensor 9 is arranged on the straight section 6 of the steel tower.

[0042] As an embodiment of the present invention, a wind turbine box 7 is arranged on the top of the steel tower straight section 6, a wind turbine box 7 is arranged inside the wind turbine box 7, and a driving shaft of the wind turbine passes through the wind turbine box 7 and is connected to a blade connecting component 8.

[0043] As an embodiment of the present invention, a stress monitoring box 14 is arranged on the foundation 1 of the mixed tower wind turbine, and the fifth fiber grating sensor 9, the fourth fiber grating sensor 10, the third fiber grating sensor 11, the second fiber grating sensor 12 and the first fiber grating sensor 13 are connected to the stress monitoring box 14.

[0044] As an implementation mode of the present invention, the stress monitoring box 14 is fixed on the foundation 1 of the mixed tower wind turbine by means of anchor screws.

[0045] As an embodiment of the present invention, reference Figure 2 The stress monitoring box 14 includes a JEME-IFBG / D04 demodulator 16 and a 4G DTU wireless communication module 17. The No. 5 fiber grating sensor 9, the No. 4 fiber grating sensor 10, the No. 3 fiber grating sensor 11, the No. 2 fiber grating sensor 12 and the No. 1 fiber grating sensor 13 are connected to the JEME-IFBG / D04 demodulator 16. The JEME-IFBG / D04 demodulator 16 is connected to the remote server 18 via the 4G DTU wireless communication module 17.

[0046] As an embodiment of the present invention, the JEME-IFBG / D04 demodulator 16 is set on multiple interfaces, and can simultaneously access the strain information output by the fiber grating sensor No. 5 9, the fiber grating sensor No. 4 10, the fiber grating sensor No. 3 11, the fiber grating sensor No. 2 12 and the fiber grating sensor No. 1 13, and then demodulate it through the JEME-IFBG / D04 demodulator 16, and then send it to the remote server 18 via the 4G DTU wireless communication module 17.

[0047] As an embodiment of the present invention, in view of the existence of factors such as foundation stiffness, mass distribution of the hybrid tower, center of gravity distribution of the main components of the cabin and impeller, the stress concentration point of the steel-hybrid tower is obtained through numerical simulation, and a fiber grating sensor is installed at the stress concentration point.

[0048] As an embodiment of the present invention, for example, when the height of the steel-concrete tower is 55 mm, the heights of the stress concentration points of each section from the ground are 5 m, 13 m, 16 m, 27 m and 36 m respectively, and a No. 1 fiber grating sensor 13, a No. 2 fiber grating sensor 12, a No. 3 fiber grating sensor 11, a No. 4 fiber grating sensor 10 and a No. 5 fiber grating sensor 9 are arranged at the stress concentration points of each section respectively, wherein the No. 1 fiber grating sensor 13, the No. 2 fiber grating sensor 12, the No. 3 fiber grating sensor 11, the No. 4 fiber grating sensor 10 and the No. 5 fiber grating sensor 9 are fixed to the outer wall of the steel-concrete tower by screws 20 and wire nails 19 respectively, as shown in FIG. Figure 3 shown.

[0049] As an embodiment of the present invention, the fiber grating sensor No. 1 13, the fiber grating sensor No. 2 12, the fiber grating sensor No. 3 11, the fiber grating sensor No. 4 10 and the fiber grating sensor No. 5 9 are all FBG fiber Bragg grating sensors. In addition to the advantage that the optical fiber itself is composed of dielectrics and therefore does not require a power source, the FBG fiber Bragg grating sensor also has the advantages of being anti-electromagnetic interference, resistant to extreme temperatures, resistant to corrosion, small in size and light in weight, and having a large transmission capacity and low loss. The FBG fiber Bragg grating sensor has high precision, which can reach ±1με.

[0050] JEME-IFBG / D04 demodulator 16 has the advantages of small size and easy to carry.

[0051] The 4G DTU wireless communication module 17 is programmable and supports secondary development. It can transmit the strain information collected by the JEME-IFBG / D04 demodulator 16 to the remote server 18 in real time through two information transmission modes: SMS transmission and network transmission. At the same time, it can cache data when the network is disconnected.

[0052] The output end of the JEME-IFBG / D04 demodulator 16 is a USB interface, and the input end of the 4G DTU wireless communication module 17 is a VGA interface.

[0053] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and disclosure of the invention. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the following claims.

[0054] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0055] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A stress monitoring device suitable for bearing components of a mixed tower wind turbine, characterized in that: The invention comprises a remote server (18); a steel-concrete tower is erected on a mixed tower wind turbine foundation (1); a fiber optic Bragg grating monitoring device (15) is arranged on the steel-concrete tower; a stress monitoring box (14) is arranged on the mixed tower wind turbine foundation (1); the fiber optic Bragg grating monitoring device (15) is connected to the stress monitoring box (14); and the stress monitoring box (14) is connected to the remote server (18).

2. The stress monitoring device for the bearing components of a mixed-tower wind turbine according to claim 1 is characterized in that: The steel-concrete tower is divided from bottom to top into a first straight section (2) of the concrete tower, a first variable cross-section section (3) of the concrete tower, a second straight section (4) of the concrete tower, a second variable cross-section section (5) of the concrete tower and a straight section (6) of the steel tower.

3. The stress monitoring device for bearing components of a mixed-tower wind turbine according to claim 2 is characterized in that: The fiber grating monitoring device (15) comprises a first fiber grating sensor (13), a second fiber grating sensor (12), a third fiber grating sensor (11), a fourth fiber grating sensor (10) and a fifth fiber grating sensor (9), wherein the first fiber grating sensor (13) is arranged on the first straight section (2) of the concrete tower, the second fiber grating sensor (12) is arranged on the first variable cross-section section (3) of the concrete tower, the third fiber grating sensor (11) is arranged on the second straight section (4) of the concrete tower, the fourth fiber grating sensor (10) is arranged on the second variable cross-section section (5) of the concrete tower, and the fifth fiber grating sensor (9) is arranged on the straight section (6) of the steel tower; A No. 1 fiber grating sensor (13), a No. 2 fiber grating sensor (12), a No. 3 fiber grating sensor (11), a No. 4 fiber grating sensor (10) and a No. 5 fiber grating sensor (9) are connected to a stress monitoring box (14).

4. The stress monitoring device for bearing components of a mixed-tower wind turbine according to claim 1 is characterized in that: The stress monitoring box (14) comprises a JEME-IFBG / D04 demodulator (16) and a 4G DTU wireless communication module (17), the fiber grating monitoring device (15) is connected to the JEME-IFBG / D04 demodulator (16), and the JEME-IFBG / D04 demodulator (16) is connected to a remote server (18) via the 4G DTU wireless communication module (17).

5. The stress monitoring device for bearing components of a mixed-tower wind turbine according to claim 4 is characterized in that: The output end of the JEME-IFBG / D04 demodulator (16) is a USB interface, and the input end of the 4G DTU wireless communication module (17) is a VGA interface.

6. The stress monitoring device for bearing components of a mixed-tower wind turbine according to claim 1, characterized in that: The optical fiber grating monitoring device (15) is fixed on the outer wall of the steel-concrete tower by means of screws (20) and thread fixing nails (19).

7. The stress monitoring device for bearing components of a mixed-tower wind turbine according to claim 1 is characterized in that: The stress monitoring box (14) is fixed on the foundation (1) of the mixed tower wind turbine generator by means of anchor screws.

8. The stress monitoring device for bearing components of a mixed-tower wind turbine according to claim 1 is characterized in that: A wind turbine box (7) is arranged at the top of the steel tower straight section (6), a wind turbine box (7) is arranged inside the wind turbine box (7), and a driving shaft of the wind turbine box is connected to a blade connecting component (8) after passing through the wind turbine box (7).

9. A stress monitoring device suitable for bearing components of a mixed tower wind turbine, characterized in that: The invention comprises a remote server (18); a steel-concrete tower is erected on a mixed tower wind turbine foundation (1); a fiber grating monitoring device (15) is arranged on the steel-concrete tower; a stress monitoring box (14) is arranged on the mixed tower wind turbine foundation (1); the fiber grating monitoring device (15) is connected to the stress monitoring box (14); and the stress monitoring box (14) is connected to the remote server (18); The steel-concrete tower is divided from bottom to top into a first straight section (2) of a concrete tower, a first variable cross-section section (3) of a concrete tower, a second straight section (4) of a concrete tower, a second variable cross-section section (5) of a concrete tower and a straight section (6) of a steel tower; A wind turbine box (7) is arranged at the top of the steel tower straight section (6), a wind turbine box (7) is arranged inside the wind turbine box (7), and a driving shaft of the wind turbine box is connected to a blade connecting component (8) after passing through the wind turbine box (7).

10. The stress monitoring device for bearing components of a mixed-tower wind turbine according to claim 9, characterized in that: The fiber grating monitoring device (15) comprises a first fiber grating sensor (13), a second fiber grating sensor (12), a third fiber grating sensor (11), a fourth fiber grating sensor (10) and a fifth fiber grating sensor (9), wherein the first fiber grating sensor (13) is arranged on the first straight section (2) of the concrete tower, the second fiber grating sensor (12) is arranged on the first variable cross-section section (3) of the concrete tower, the third fiber grating sensor (11) is arranged on the second straight section (4) of the concrete tower, the fourth fiber grating sensor (10) is arranged on the second variable cross-section section (5) of the concrete tower, and the fifth fiber grating sensor (9) is arranged on the straight section (6) of the steel tower; A No. 1 fiber grating sensor (13), a No. 2 fiber grating sensor (12), a No. 3 fiber grating sensor (11), a No. 4 fiber grating sensor (10) and a No. 5 fiber grating sensor (9) are connected to a stress monitoring box (14).

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