Wiring structure of wind driven generator

Abstract

The invention belongs to the technical field of wind power generation, and particularly relates to a wind driven generator wiring structure which comprises a wind driven generator, a transformer, a high-voltage control cabinet, a first connecting conductor, a second connecting conductor, a third connecting conductor, a jumper wire, a strain insulator string and an overhead conductor. The transformer is fixedly mounted in a cabin or a tower drum of the wind driven generator, and the high-voltage control cabinet is fixedly mounted in the tower drum; the first connecting conductor is connected between a wire outlet end of a converter of the wind driven generator and a low-voltage side of a transformer; the second connecting conductor is connected between the high-voltage side of the transformer and the wire inlet busbar of the high-voltage control cabinet; the first end part of the third connecting conductor is connected to an outgoing line busbar of the high-voltage control cabinet, and the second end part of the third connecting conductor penetrates out of the tower drum through a wall bushing; one end of the overhead conductor is fixedly connected to the outer side of the tower drum through a strain insulator string, and the other end of the overhead conductor is used for being connected with a high-voltage stringing tower; the jumper wire is connected between the second end portion and the overhead conductor.

Description

Technical Field

[0001] The invention belongs to the technical field of wind power generation, and in particular relates to a wind generator connection structure. Background Art

[0002] As competition in the wind power industry becomes increasingly fierce, the development and changes of wind turbines themselves are becoming increasingly apparent. In the context of electricity market transactions, wind power bidding for access to the grid has become a trend. Problems such as large footprint of wind turbine boxes and high cost of connecting cables have become prominent, which has seriously restricted the sustainable and rapid development of the wind power industry.

[0003] The wiring structure of wind turbines in the prior art can generally be divided into the following two categories. The first category is to set up a wind turbine box transformer outside the wind turbine. The second category is to arrange the transformer inside the tower or nacelle of the wind turbine, and also arrange the high-voltage control cabinet inside the tower or nacelle of the wind turbine to replace the wind turbine box transformer. When the first type of arrangement is adopted, if the foundation of the wind turbine box transformer exceeds the outer edge of the wind turbine foundation, additional land will be required, which will increase the construction cost. However, when the second type of arrangement is adopted, no additional land will be required, which can effectively reduce the construction cost.

[0004] However, since the wind turbine transformer or high-voltage control cabinet in the wind turbine wiring structure is usually far away from the terminal tower, it is necessary to directly bury high-voltage cables between the wind turbine transformer (or high-voltage control cabinet) and the terminal tower to transmit electrical energy to the overhead collection line. This has technical problems such as large amount of high-voltage cables used and high construction costs. Summary of the Invention

[0005] In order to solve the above-mentioned defects of the prior art, the present invention provides a wind turbine connection structure to solve the technical problems of the existing wind turbine connection structure, such as large amount of high-voltage cables used and high construction cost.

[0006] In order to achieve the above-mentioned object, the technical solution of the present invention is as follows: A wind turbine connection structure, characterized in that it includes: a wind turbine, a transformer, a high-voltage control cabinet, a first connecting conductor, a second connecting conductor, a third connecting conductor, a jumper, a tension insulator string and an overhead conductor; The transformer is fixedly installed in the nacelle or tower of the wind turbine, and the high-voltage control cabinet is fixedly installed in the tower; the first connecting conductor is arranged in the nacelle and / or the tower, and is connected between the output terminal of the converter of the wind turbine and the low-voltage side of the transformer; the second connecting conductor is arranged in the nacelle and / or the tower, and is connected between the high-voltage side of the transformer and the incoming busbar of the high-voltage control cabinet; The first end of the third connecting conductor is connected to the outgoing busbar of the high-voltage control cabinet, and the second end of the third connecting conductor passes through the wall bushing to the outside of the tower; One end of the overhead conductor is fixedly connected to the outside of the tower through the tension insulator string, and the other end of the overhead conductor is used to be connected to the high-voltage transmission tower; the second end is arranged below the connection point of the tension insulator string on the tower, and the jumper is connected between the second end and the overhead conductor.

[0007] By arranging the third connecting conductor, the jumper, the tension insulator string and the overhead wire, the tower of the wind turbine connection structure provided by the present invention can also serve as a terminal tower, greatly reducing the distance between the high-voltage control cabinet and the terminal tower (that is, the tower in the present invention). Compared with the existing wind turbine connection structure, there is no need to connect the wind turbine box transformer (or high-voltage control cabinet) and the overhead collection line on the terminal tower through directly buried high-voltage cables, and the flexibility of the design of the high-voltage collection line network (including high-voltage line towers and overhead collection lines) is improved, which can be used to further optimize the design of the high-voltage collection line network. Since overhead wires have the advantages of low cost, low investment, simple construction, and easy installation compared to high-voltage cables, even if the high-voltage collection line network design is the same, the wind turbine connection structure provided by the present invention can save a lot of construction costs compared to the existing wind turbine connection structure, solving the technical problems of large high-voltage cable usage and high construction cost in the existing wind turbine connection structure.

[0008] Furthermore, the converter and the transformer are both fixedly installed in the nacelle, and the first connecting conductor is arranged in the nacelle.

[0009] By fixedly installing the converter and the transformer in the nacelle and arranging the first connecting conductor in the nacelle, the distance between the converter and the transformer can be effectively reduced, thereby reducing the length of the low-voltage connecting conductor (i.e., the first connecting conductor) and reducing line loss.

[0010] Furthermore, the wind turbine connection structure further includes a fireproof partition fixedly installed in the nacelle, wherein the fireproof partition is used to separate the inner cavity of the nacelle into a first installation chamber and a second installation chamber sequentially arranged along the central axis of the nacelle; The first installation chamber is used for fixedly installing the wind turbine set and the converter of the wind turbine, and the second installation chamber is used for fixedly installing the transformer. The wind turbine set is arranged on a side of the first installation chamber away from the second installation chamber, and the converter is arranged on a side of the first installation chamber close to the second installation chamber. The wind wheel of the wind turbine is installed on the outside of one end of the first installation chamber away from the second installation chamber.

[0011] By providing the fireproof partition, the transformer can be arranged in an independent isolation room (ie, the second installation room) for fireproof isolation.

[0012] Furthermore, the second installation room is also provided with an automatic fire extinguishing device.

[0013] Furthermore, the fire resistance limit of the fireproof partition is not less than one hour.

[0014] Furthermore, the converter adopts a wiring method of upper outgoing line, and the low-voltage side of the transformer adopts a wiring method of upper incoming line; The first connecting conductor is fixedly installed on the upper inner wall of the cabin through a hanger, one end of the first connecting conductor is laid above the converter and then extends downward to be fixedly connected to the output terminal of the converter; the other end of the first connecting conductor is laid above the low-voltage side of the transformer and then extends downward to be fixedly connected to the low-voltage side.

[0015] Furthermore, the first connecting conductor is a hard conductor or a bare conductor.

[0016] In the existing wind turbine connection structure, multiple low-voltage cables are usually laid in parallel to connect the low-voltage side of the transformer and the converter of the wind turbine. However, this connection method will cause the cable to be laid low, thereby increasing the number of low-voltage cables laid in parallel. With the development of wind power generation, the capacity of wind turbines has been continuously increasing (the motor capacity of onshore wind turbines has increased from 1.5MW to 11MW, and the capacity of offshore wind turbines has increased from 2.5MW to 18MW). As the capacity of wind turbines gradually increases, the above problem will cause the number of low-voltage cables laid in parallel to increase rapidly. The increase is costly and it is difficult to meet the requirements of economical connection of the low-voltage side of large-capacity wind turbine transformers. Compared with the traditional connection method through parallel laying of multiple low-voltage cables, the wind turbine wiring structure provided by the present invention is able to effectively avoid the technical problems of the traditional connection method through parallel laying of multiple low-voltage cables, such as the large number of low-voltage cables, difficult laying and high cost, by setting the first connecting conductor to a hard conductor or a bare conductor with stronger short-circuit current resistance, better oxidation resistance, convenient construction, low cost, good heat dissipation and high mechanical strength. At the same time, it can also facilitate the operation and maintenance personnel to carry out the later maintenance work.

[0017] Furthermore, the current-carrying cross-sectional area of ​​the first connecting conductor is not less than a preset cross-sectional area; The preset cross-sectional area is calculated using the following formula: ; Wherein, S is the preset cross-sectional area; Q is the thermal effect of the short-circuit current of the first connecting conductor; C is the conductor material coefficient of the first connecting conductor; The value range of the conductor material coefficient C is calculated using the following formula: ; Among them, C is the conductor material coefficient of the first connecting conductor; K is the first empirical constant; τ is the second empirical constant; t1 is the heating temperature of the first connecting conductor before short-circuiting; and t2 is the maximum allowable temperature when the first connecting conductor is short-circuited.

[0018] When the material of the first connecting conductor is copper, the first empirical constant K=522×10 6 (Unit: W×s / Ω×cm 4 ), the second empirical constant τ = 235℃; When the material of the first connecting conductor is aluminum, the first empirical constant K=222×10 6 (Unit: W×s / Ω×cm 4 ), the second empirical constant, the second empirical constant τ=245℃.

[0019] When the material of the first connecting conductor is copper, the maximum allowable temperature t2 is 300° C.; when the material of the first connecting conductor is aluminum or aluminum-manganese alloy, the maximum allowable temperature t2 is 200° C.

[0020] Furthermore, the allowable current carrying capacity of the first connecting conductor is not less than the designed current carrying capacity; The design current carrying capacity is calculated using the following formula: ; Among them, I do is the designed current carrying capacity; I1 is the maximum transmission current on the low-voltage side of the transformer; P is the rated power of the wind turbine; V is the rated voltage at the low-voltage side outlet of the wind turbine; cosφ is the power factor of the wind turbine; K1 is the current carrying capacity correction coefficient of the first connecting conductor.

[0021] The value of the current-carrying capacity correction coefficient K1 of the first connecting conductor is related to the altitude and ambient temperature of the area where the wind turbine is arranged, and is also related to the laying method of the first connecting conductor.

[0022] Furthermore, the maximum allowable stress value of the first connecting conductor is not less than the design stress value; The design stress value is calculated using the following formula: ; Wherein, σ1 is the design stress value; σ x-x σ is the maximum mechanical stress generated between the phases of the first connecting conductor when short-circuited; x It is the mechanical stress caused by the interaction between the same-phase conductor pieces of the first connecting conductor when short-circuited.

[0023] Furthermore, the high-voltage control cabinet is fixedly installed at the bottom of the inner cavity of the tower, the high-voltage control cabinet adopts a top-in and top-out wiring method, and the high-voltage side of the transformer adopts a bottom-out wiring method; The second connecting conductor is a soft wire, which is arranged in a vertical direction. The second connecting conductor is fixedly mounted on the inner wall of the tower through a plurality of support insulators. The upper end of the second connecting conductor passes through the cabin and is connected to the high-voltage side of the transformer, and the lower end of the second connecting conductor is connected to the incoming busbar of the high-voltage control cabinet.

[0024] Furthermore, the second connecting conductor is steel-core aluminum stranded wire, aluminum-clad steel-core aluminum stranded wire or steel stranded wire.

[0025] Furthermore, the value range of the cross-sectional area of ​​the second connecting conductor is calculated using the following formula: ; Among them, S1 is the conductor cross-sectional area of ​​the second connecting conductor; P is the rated power of the wind turbine; J is the economic current density of the second connecting conductor; V1 is the rated voltage of the high-voltage side of the transformer; cosφ is the power factor of the wind turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the implementation. Obviously, the drawings described below are only some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0027] Figure 1 1 is a schematic structural diagram of a wind turbine connection structure in an embodiment; Figure 2 is a cross-sectional view of the wiring structure of a wind turbine generator in an embodiment; Figure 3 yes Figure 1 A partial enlarged view of area A in the middle; Among them, 1 - transformer, 2 - high-voltage control cabinet, 3 - first connecting conductor, 4 - second connecting conductor, 5 - third connecting conductor, 6 - jumper, 7 - tension insulator string, 8 - overhead conductor, 9 - converter, 10 - high-voltage pylon, 11 - nacelle, 12 - tower, 13 - fireproof partition, 14 - wind turbine, 15 - wind rotor, 16 - hanger, 17 - pillar insulator; 11.1—First installation room, 11.2—Second installation room. DETAILED DESCRIPTION

[0028] 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 only part of the embodiments of the present invention, rather than all the embodiments.

[0029] like Figures 1 to 3 As shown, this embodiment provides a wind turbine connection structure, characterized in that it includes: a wind turbine, a transformer 1, a high-voltage control cabinet 2, a first connecting conductor 3, a second connecting conductor 4, a third connecting conductor 5, a jumper 6, a tension insulator string 7 and an overhead conductor 8; The transformer 1 is fixedly installed in the nacelle 11 or tower 12 of the wind turbine, and the high-voltage control cabinet 2 is fixedly installed in the tower 12; the first connecting conductor 3 is arranged in the nacelle 11 and / or tower 12, and is connected between the output terminal of the converter 9 of the wind turbine and the low-voltage side of the transformer 1; the second connecting conductor 4 is arranged in the nacelle 11 and / or tower 12, and is connected between the high-voltage side of the transformer 1 and the incoming busbar of the high-voltage control cabinet 2; The first end of the third connecting conductor 5 is connected to the outgoing busbar of the high-voltage control cabinet 2, and the second end of the third connecting conductor 5 passes through the wall bushing to the outside of the tower 12; One end of the overhead conductor 8 is fixedly connected to the outside of the tower 12 through the tension insulator string 7, and the other end of the overhead conductor 8 is used to be connected to the high-voltage transmission tower 10; the second end is arranged below the connection point of the tension insulator string 7 on the tower 12, and the jumper 6 is connected between the second end and the overhead conductor 8.

[0030] By arranging the third connecting conductor 5, the jumper 6, the tension insulator string 7 and the overhead wire 8, the tower 12 of the wind turbine connection structure provided by the present invention can also serve as a terminal tower, greatly reducing the distance between the high-voltage control cabinet 2 and the terminal tower (that is, the tower 12 in the present invention). Compared with the existing wind turbine connection structure, there is no need to connect the wind turbine box transformer (or the high-voltage control cabinet 2) and the overhead collection line on the terminal tower through direct-buried high-voltage cables, and the flexibility of the design of the high-voltage collection line network (including the high-voltage line tower 10 and the overhead collection line) is improved, which can be used to further optimize the design of the high-voltage collection line network. Since the overhead wire 8 has the advantages of low cost, low investment, simple construction, and easy installation compared with the high-voltage cable, even if the high-voltage collection line network design is the same, the wind turbine connection structure provided by the present invention can save a lot of construction costs compared with the existing wind turbine connection structure, solving the technical problems of large high-voltage cable usage and high construction cost in the existing wind turbine connection structure.

[0031] In one embodiment, Figure 1 and Figure 2 As shown, the converter 9 and the transformer 1 are both fixedly installed in the nacelle 11 , and the first connecting conductor 3 is provided in the nacelle 11 .

[0032] By fixing the converter 9 and the transformer 1 in the nacelle 11 and arranging the first connecting conductor 3 in the nacelle 11, the distance between the converter 9 and the transformer 1 can be effectively reduced, thereby reducing the length of the low-voltage connecting conductor (i.e., the first connecting conductor 3) and reducing line loss.

[0033] In one embodiment, Figure 1 and Figure 2 As shown, the wind turbine connection structure further includes a fireproof partition 13 fixedly installed in the nacelle 11, and the fireproof partition 13 is used to separate the inner cavity of the nacelle 11 into a first installation chamber 11.1 and a second installation chamber 11.2 arranged in sequence along the central axis of the nacelle 11; The first installation chamber 11.1 is used for fixedly installing the wind turbine set 14 and the converter 9 of the wind turbine, and the second installation chamber 11.2 is used for fixedly installing the transformer 1. The wind turbine set 14 is arranged on the side of the first installation chamber 11.1 away from the second installation chamber 11.2, and the converter 9 is arranged on the side of the first installation chamber 11.1 close to the second installation chamber 11.2. The wind turbine rotor 15 is installed on the outside of the end of the first installation chamber 11.1 away from the second installation chamber 11.2.

[0034] By providing the fireproof partition 13 , the transformer 1 can be arranged in an independent isolation room (ie, the second installation room 11 . 2 ) for fireproof isolation.

[0035] Preferably, in this embodiment, an automatic fire extinguishing device is also provided in the second installation chamber 11.2.

[0036] Specifically, in this embodiment, the fireproof partition 13 has a fire resistance limit of not less than one hour.

[0037] Specifically, in this embodiment, Figure 2 As shown, the converter 9 adopts the wiring method of the upper outgoing line, and the low-voltage side of the transformer 1 adopts the wiring method of the upper incoming line; The first connecting conductor 3 is fixedly mounted on the upper inner wall of the cabin 11 through a hanger 16. One end of the first connecting conductor 3 is laid above the converter 9 and then extends downward to be fixedly connected to the output terminal of the converter 9; the other end of the first connecting conductor 3 is laid above the low-voltage side of the transformer 1 and then extends downward to be fixedly connected to the low-voltage side.

[0038] Preferably, in this embodiment, the first connecting conductor 3 is a hard conductor or a bare conductor.

[0039] In the existing wind turbine connection structure, a plurality of low-voltage cables are usually laid in parallel to connect the low-voltage side of the transformer 1 and the converter 9 of the wind turbine. However, such a connection method will cause the cable to be laid in a low position, thereby increasing the number of low-voltage cables laid in parallel. With the development of the field of wind power generation, the capacity of a single wind turbine is constantly increasing (the capacity of an onshore wind turbine has increased from 1.5MW to 11MW, and the capacity of an offshore wind turbine has increased from 2.5MW to 18MW). As the capacity of the wind turbine gradually increases, the above problem will cause the number of low-voltage cables laid in parallel to increase rapidly. The cost is increasing rapidly, and it is difficult to meet the requirements of economical connection of the low-voltage side of the large-capacity wind turbine transformer 1. Compared with the traditional method of connecting by laying multiple low-voltage cables in parallel, the wind turbine connection structure provided by the present invention is to set the first connecting conductor 3 as a hard conductor or bare conductor with stronger short-circuit current resistance, better oxidation resistance, convenient construction, low cost, good heat dissipation and high mechanical strength. It can effectively avoid the technical problems of the traditional method of connecting by laying multiple low-voltage cables in parallel, such as the large number of low-voltage cables, difficult laying and high cost, and can also facilitate the operation and maintenance personnel to carry out the later maintenance work.

[0040] Specifically, in this embodiment, the first connecting conductor 3 should simultaneously meet the requirements of circuit current carrying capacity, short-circuit thermal stability and short-circuit dynamic stability, and should be selected based on the maximum cross-section calculated according to the above requirements; Among them, the requirement for short-circuit thermal stability is: the current-carrying cross-sectional area of ​​the first connecting conductor 3 is not less than the preset cross-sectional area; the requirement for loop current carrying capacity is: the allowable current carrying capacity of the first connecting conductor 3 is not less than the designed current carrying capacity; the requirement for short-circuit dynamic stability is: the maximum allowable stress value of the first connecting conductor 3 is not less than the designed stress value.

[0041] Specifically, in this embodiment, the current-carrying cross-sectional area of ​​the first connecting conductor 3 is not less than the preset cross-sectional area; The preset cross-sectional area is calculated using the following formula: ; Wherein, S is the preset cross-sectional area; Q is the thermal effect of the short-circuit current of the first connecting conductor 3; C is the conductor material coefficient of the first connecting conductor 3; The value range of the conductor material coefficient C is calculated using the following formula: ; Wherein, C is the conductor material coefficient of the first connecting conductor 3; K is the first empirical constant; τ is the second empirical constant; t1 is the heating temperature of the first connecting conductor 3 before short circuit; t2 is the maximum allowable temperature when the first connecting conductor 3 is short circuited.

[0042] When the material of the first connecting conductor 3 is copper, the first empirical constant K=522×10 6 (Unit: W×s / Ω×cm 4 ), the second empirical constant τ = 235℃; When the material of the first connecting conductor 3 is aluminum, the first empirical constant K=222×10 6 (Unit: W×s / Ω×cm 4 ), the second empirical constant τ=245℃.

[0043] When the material of the first connecting conductor 3 is copper, the maximum allowable temperature t2 = 300° C.; when the material of the first connecting conductor 3 is aluminum or aluminum-manganese alloy, the maximum allowable temperature t2 = 200° C.

[0044] Specifically, in this embodiment, the allowable current carrying capacity of the first connecting conductor 3 is not less than the designed current carrying capacity; The design current carrying capacity is calculated using the following formula: ; Among them, I do is the designed current carrying capacity; I1 is the maximum transmission current on the low-voltage side of the transformer 1; P is the rated power of the wind turbine; V is the rated voltage at the low-voltage side outlet of the wind turbine; cosφ is the power factor of the wind turbine; K1 is the current carrying capacity correction coefficient of the first connecting conductor 3.

[0045] The value of the current-carrying capacity correction coefficient K1 of the first connecting conductor 3 is related to the altitude and ambient temperature of the area where the wind turbine is arranged, and is also related to the installation method of the first connecting conductor 3 .

[0046] Specifically, in this embodiment, the maximum allowable stress value of the first connecting conductor 3 is not less than the design stress value; The design stress value is calculated using the following formula: ; Among them, σ1 is the design stress value; σ x-x is the maximum mechanical stress generated between the phases of the first connecting conductor 3 during short circuit; x It is the mechanical stress caused by the interaction between the same-phase conductor pieces of the first connection conductor 3 during short circuit.

[0047] In actual applications, the connecting conductor on the high-voltage side of the transformer 1 (ie, the second connecting conductor 4 ) may be a high-voltage cable or a flexible wire.

[0048] Specifically, in this embodiment, Figures 1 to 3 As shown, the high-voltage control cabinet 2 is fixedly installed at the bottom of the inner cavity of the tower 12. The high-voltage control cabinet 2 adopts a top-in and top-out wiring method, and the high-voltage side of the transformer 1 adopts a bottom-out wiring method; The second connecting conductor 4 is a soft wire, and is arranged in the vertical direction. The second connecting conductor 4 is fixedly mounted on the inner wall of the tower 12 through a plurality of support insulators 17. The upper end of the second connecting conductor 4 passes through the nacelle 11 and is connected to the high voltage side of the transformer 1. The lower end of the second connecting conductor 4 is connected to the incoming busbar of the high voltage control cabinet 2 (at Figure 1 and Figure 3 In the figure, the lower section of the second connecting conductor 4 is partially overlapped and blocked by the third connecting conductor 5 and is therefore not fully shown).

[0049] Among them, commonly used soft wires include steel core aluminum stranded wire, aluminum clad steel core aluminum stranded wire and steel stranded wire.

[0050] In this embodiment, the second connecting conductor 4 is a steel-core aluminum stranded wire, an aluminum-clad steel-core aluminum stranded wire, or a steel stranded wire.

[0051] When the second connecting conductor 4 is a soft wire, the selection of the second connecting conductor 4 needs to comprehensively consider factors such as environmental conditions, loop current, wire corona, radio interference, etc.; in coastal areas where the air contains high salt content or places with corrosive gases, corrosion-resistant soft wires should be used as much as possible; and when the second connecting conductor 4 is a soft wire, the cross-section of the soft wire needs to be selected according to the economic current density based on the continuous working current of the loop.

[0052] Specifically, in this embodiment, the value range of the wire cross-sectional area of ​​the second connecting conductor 4 is calculated using the following formula: ; Among them, S1 is the conductor cross-sectional area of ​​the second connecting conductor 4; P is the rated power of the wind turbine; J is the economic current density of the second connecting conductor 4; V1 is the rated voltage of the high-voltage side of the transformer 1; and cosφ is the power factor of the wind turbine.

[0053] For onshore wind power projects, the number of power generation hours is generally less than 3000h. At this time, the economic current density J of the second connecting conductor 4 is usually 1.65A / mm2. For offshore wind power projects, the number of power generation hours in some areas can reach 3000h~5000h. At this time, the economic current density J of the second connecting conductor 4 is usually 1.15A / mm2.

[0054] The implementation of this embodiment is further explained by taking an existing wind farm project as an example: The wind farm has 48 6.25MW wind turbines with a total capacity of 300MW. The wind turbines have a power factor of 0.95, the high-voltage side of the transformer is rated at 35kV, the low-voltage side is rated at 1.14kV, and the turbine hub height is 160m.

[0055] Option 1: Use the existing wind turbine wiring structure.

[0056] The current on the low-voltage side of the box-type transformer is 3332A, and the current on the high-voltage side of the box-type transformer is 109A.

[0057] For the high voltage side of the box-type transformer, a 35kV cross section of 3×95mm is used. 2 Copper core cable that meets the current carrying capacity requirements needs to use YIY23-26 / 35-3×95mm 2 The copper core cable length is about 120m.

[0058] For the low-voltage side of the box-type transformer, since multiple cables are laid in parallel through pipes, it is necessary to consider the soil thermal resistance coefficient and the parallel laying coefficient of multiple cables. The cable selection for the low-voltage side of the box-type transformer is shown in Table 1: Table 1: Cable selection for low-voltage side of box-type transformer:

[0059] ; Considering the low resistivity, small bending radius and high reliability of copper core cables, the project initially adopted 11 3×400 copper core cables as the power cables on the low voltage side of the box-type transformer. The neutral cable of the wind turbine was 150mm. 2Because low-voltage cables are used to connect the nacelle fans to the control cabinet at the base of the tower, and vice versa, a single fan uses 1,760 meters of YJY23-1.8 / 3kV-3×400 copper-core cables and 160 meters of YJY23-1.8 / 3kV-1×150 copper-core cables.

[0060] Solution 2: Using the wind turbine connection structure provided in this embodiment.

[0061] For the high voltage side of the transformer, according to the calculation formula of the value range of the conductor cross-sectional area of ​​the second connecting conductor 4, it can be obtained that the conductor cross-sectional area of ​​the second connecting conductor 4 shall not be less than 65 mm 2 Therefore, the second connecting conductor 4 can adopt JL / G1A-95 / 20 steel core aluminum stranded wire.

[0062] For the low-voltage side of the transformer, referring to the Technical Specification for Conductor and Electrical Appliance Selection and Design (DL / T 5222-2005), since the maximum current is less than 4000A, the first connecting conductor 3 can be a rectangular copper conductor (a type of hard conductor). Since the first connecting conductor 3 should simultaneously meet the requirements of loop current carrying capacity, short-circuit thermal stability, and short-circuit dynamic stability, the first connecting conductor 3 can be four 100×8 rectangular copper conductors.

[0063] The selected transformer 1 weighs approximately 20 tons, while the total weight of the nacelle 11, wind turbine 14, and rotor 15 is approximately 300 tons. The integration of the transformer 1 within the nacelle 11 only increases the total weight by 6.7%, significantly impacting the structure of the wind turbine's foundation and tower 12. Therefore, the impact of the transformer 1's integration into the nacelle on the cost of the foundation and tower 12 is negligible. Furthermore, the wind turbine wiring structure provided by this embodiment facilitates the placement of the transformer 1 as the wind turbine's capacity increases, providing more space within the nacelle.

[0064] The economic comparison of the above two solutions is shown in Table 2: Table 2: Comparison of economic efficiency between Option 1 and Option 2

[0065] ; The wind turbine connection structure provided by the present invention has at least the following technical effects or advantages: 1. By providing a third connecting conductor 5, a jumper 6, a tension insulator string 7 and an overhead conductor 8, the tower 12 of the wind turbine connection structure provided by the present invention can also serve as a terminal tower, greatly reducing the distance between the high-voltage control cabinet 2 and the terminal tower (i.e., the tower 12 in the present invention). Compared with the existing wind turbine connection structure, there is no need to directly bury high-voltage cables to connect the wind turbine box transformer (or the high-voltage control cabinet 2) and the overhead collector line on the terminal tower, and the flexibility of the design of the high-voltage collector line network (including the high-voltage transmission tower 10 and the overhead collector line) is improved, which can be used to further optimize the design of the high-voltage collector line network. Since the overhead conductor 8 has the advantages of low cost, low investment, simple construction, and easy installation compared to high-voltage cables, even if the high-voltage collector line network design is the same, the wind turbine connection structure provided by the present invention can save a lot of construction costs compared to the existing wind turbine connection structure, solving the technical problems of large high-voltage cable usage and high construction cost in the existing wind turbine connection structure.

[0066] 2. By fixing the converter 9 and the transformer 1 in the nacelle 11 and arranging the first connecting conductor 3 in the nacelle 11, the distance between the converter 9 and the transformer 1 can be effectively reduced, thereby reducing the length of the low-voltage connecting conductor (i.e., the first connecting conductor 3) and reducing line loss.

[0067] 3. By providing a fireproof partition 13, the transformer 1 can be arranged in an independent isolation room (ie, the second installation room 11.2) for fireproof isolation.

[0068] 4. In the existing wind turbine connection structure, multiple low-voltage cables are usually laid in parallel to connect the low-voltage side of the transformer 1 and the converter 9 of the wind turbine. However, this connection method will cause the cable to be laid in a low position, thereby increasing the number of low-voltage cables laid in parallel. With the development of wind power generation, the capacity of wind turbines has been continuously increasing (the capacity of onshore wind turbines has increased from 1.5MW to 11MW, and the capacity of offshore wind turbines has increased from 2.5MW to 18MW). As the capacity of wind turbines gradually increases, the above problem will lead to the number of low-voltage cables laid in parallel. The number of cables connected to the transformer 1 is increasing rapidly, and the cost is high, making it difficult to meet the requirements for economical connection of the low-voltage side of a large-capacity wind turbine transformer 1. Compared with the traditional connection method through parallel laying of multiple low-voltage cables, the wind turbine connection structure provided by the present invention can effectively avoid the technical problems of the traditional connection method through parallel laying of multiple low-voltage cables, such as the large number of low-voltage cables, difficult laying and high cost, by setting the first connecting conductor 3 as a hard conductor or bare conductor with stronger short-circuit current resistance, better oxidation resistance, convenient construction, low cost, good heat dissipation and high mechanical strength. It can also facilitate the operation and maintenance personnel to carry out the later maintenance work.

[0069] The above are only specific application examples of the present invention and do not constitute any limitation to the protection scope of the present invention. Any technical solutions formed by equivalent transformation or equivalent replacement shall fall within the protection scope of the present invention.

Claims

1. A wind turbine connection structure, characterized in that: include: Wind turbine, transformer, high-voltage control cabinet, first connecting conductor, second connecting conductor, third connecting conductor, jumper, tension insulator string and overhead conductor; The transformer is fixedly installed in the nacelle or tower of the wind turbine, and the high-voltage control cabinet is fixedly installed in the tower; the first connecting conductor is arranged in the nacelle and / or the tower, and is connected between the output terminal of the converter of the wind turbine and the low-voltage side of the transformer; the second connecting conductor is arranged in the nacelle and / or the tower, and is connected between the high-voltage side of the transformer and the incoming busbar of the high-voltage control cabinet; The first end of the third connecting conductor is connected to the outgoing busbar of the high-voltage control cabinet, and the second end of the third connecting conductor passes through the wall bushing to the outside of the tower; One end of the overhead conductor is fixedly connected to the outside of the tower through the tension insulator string, and the other end of the overhead conductor is used to be connected to the high-voltage transmission tower; the second end is arranged below the connection point of the tension insulator string on the tower, and the jumper is connected between the second end and the overhead conductor.

2. The wind turbine connection structure according to claim 1, characterized in that: The converter and the transformer are both fixedly installed in the nacelle, and the first connecting conductor is arranged in the nacelle.

3. The wind turbine connection structure according to claim 2, characterized in that: Also included is a fireproof partition fixedly installed in the cabin, the fireproof partition is used to separate the inner cavity of the cabin into a first installation room and a second installation room sequentially arranged along the central axis of the cabin; The first installation chamber is used for fixedly installing the wind turbine set and the converter of the wind turbine, and the second installation chamber is used for fixedly installing the transformer. The wind turbine set is arranged on a side of the first installation chamber away from the second installation chamber, and the converter is arranged on a side of the first installation chamber close to the second installation chamber. The wind wheel of the wind turbine is installed on the outside of one end of the first installation chamber away from the second installation chamber.

4. The wind turbine connection structure according to claim 2, characterized in that: The converter adopts the wiring mode of top outgoing line, and the low voltage side of the transformer adopts the wiring mode of top incoming line; The first connecting conductor is fixedly installed on the upper inner wall of the cabin through a hanger, one end of the first connecting conductor is laid above the converter and then extends downward to be fixedly connected to the output terminal of the converter; the other end of the first connecting conductor is laid above the low-voltage side of the transformer and then extends downward to be fixedly connected to the low-voltage side.

5. The wind turbine connection structure according to claim 2, characterized in that: The first connecting conductor is a hard conductor or a bare conductor.

6. The wind turbine connection structure according to claim 5, characterized in that: The current-carrying cross-sectional area of ​​the first connecting conductor is not less than a preset cross-sectional area; The preset cross-sectional area is calculated using the following formula: ； Wherein, S is the preset cross-sectional area; Q is the thermal effect of the short-circuit current of the first connecting conductor; C is the conductor material coefficient of the first connecting conductor; The value range of the conductor material coefficient C is calculated using the following formula: ； Among them, C is the conductor material coefficient of the first connecting conductor; K is the first empirical constant; τ is the second empirical constant; t1 is the heating temperature of the first connecting conductor before short-circuiting; and t2 is the maximum allowable temperature when the first connecting conductor is short-circuited.

7. The wind turbine connection structure according to claim 5, characterized in that: The allowable current carrying capacity of the first connecting conductor is not less than the designed current carrying capacity; The design current carrying capacity is calculated using the following formula: ； Among them, I do is the designed current carrying capacity; I1 is the maximum transmission current on the low-voltage side of the transformer; P is the rated power of the wind turbine; V is the rated voltage at the low-voltage side outlet of the wind turbine; cosφ is the power factor of the wind turbine; K1 is the current carrying capacity correction coefficient of the first connecting conductor.

8. The wind turbine connection structure according to claim 5, characterized in that: The maximum allowable stress value of the first connecting conductor is not less than the design stress value; The design stress value is calculated using the following formula: ； Wherein, σ1 is the design stress value; σ x-x σ is the maximum mechanical stress generated between the phases of the first connecting conductor when short-circuited; x It is the mechanical stress caused by the interaction between the same-phase conductor pieces of the first connecting conductor when short-circuited.

9. The wind turbine connection structure according to claim 2, characterized in that: The high-voltage control cabinet is fixedly installed at the bottom of the inner cavity of the tower, and the high-voltage control cabinet adopts a top-in and top-out wiring method, and the high-voltage side of the transformer adopts a bottom-out wiring method; The second connecting conductor is a soft wire, which is arranged in a vertical direction. The second connecting conductor is fixedly mounted on the inner wall of the tower through a plurality of support insulators. The upper end of the second connecting conductor passes through the cabin and is connected to the high-voltage side of the transformer, and the lower end of the second connecting conductor is connected to the incoming busbar of the high-voltage control cabinet.

10. The wind turbine connection structure according to claim 9, characterized in that: The cross-sectional area of ​​the second connecting conductor is calculated using the following formula: ； Among them, S1 is the conductor cross-sectional area of ​​the second connecting conductor; P is the rated power of the wind turbine; J is the economic current density of the second connecting conductor; V1 is the rated voltage of the high-voltage side of the transformer; cosφ is the power factor of the wind turbine.

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