35kV power grid direct connection type doubly-fed wind driven generator

Abstract

A cooling device is arranged on the upper portion of the 35kV power grid direct connection type doubly-fed wind generator, the 35kV power grid direct connection type doubly-fed wind generator comprises a stator, a rotor, a bearing unit and a slip ring brush holder system, the stator comprises a stator base and a stator winding assembly, the rotor is installed on the stator base, and the slip ring brush holder system is installed on the rotor. A rotor is supported and fixed through bearing units arranged at the two ends of the stator base, the stator winding assembly is directly connected with a power grid through a stator junction box, and at least one layer of cooling pipeline is arranged at the two ends of the stator winding assembly along the surface of a stator coil. The high-power, high-voltage and efficient grid-connected doubly-fed wind generator has the advantages of high single-machine power, high output voltage, low current, high heat exchange efficiency, high reliability and the like, the cost of a boosting transformer can be effectively saved, the number of cables of a unit is reduced, and the design and manufacturing cost of the whole unit is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine generators, and in particular to a 35kV grid-direct-connected double-fed wind turbine generator. Background Art

[0002] Wind turbines using doubly-fed generators have become one of the mainstream models today because of their advantages such as being able to easily achieve variable speed constant frequency, flexible independent adjustment of active and reactive power, and smaller rotor excitation capacity. In this unit, the stator of the doubly-fed generator is directly connected to the power grid, and the rotor is connected to the power grid through a converter to achieve energy conversion. The structural block diagram of the existing doubly-fed wind turbine system is shown in the figure. Figure 1 As shown, the existing double-fed generator structure is as follows Figure 2 As shown, the structure of the stator junction box of the doubly fed generator is as follows Figure 3 , 4 shown.

[0003] Specifically, Figure 1 As shown, the system uses a doubly-fed generator with a relatively low voltage level. The voltage emitted by the stator is generally low voltage electricity, which must be increased by a transformer and then connected to the power grid to achieve energy transmission; the low voltage electricity emitted by the rotor through the converter control also needs to be increased by a transformer and then connected to the power grid.

[0004] like Figure 2 As shown, the existing double-fed wind turbine generator is composed of a stator, a rotor, a bearing unit, a slip ring brush holder system, a cooling device, etc. The bearing unit includes a transmission end bearing unit and a non-transmission end bearing unit, which is connected to the stator frame to support the rotor; according to the different cooling media, the cooling device is generally divided into air-to-air cooler, air-to-water cooler, etc., and there are only one or two cooling media.

[0005] like Figure 3-4 As shown in the figure, the existing double-fed generator stator junction box, taking the 8MW double-fed generator as an example, since the current stator voltage is up to 10.5KW, the voltage is relatively low, resulting in a large current. It can be seen that each phase of the stator three-phase cable requires 8 400mm 2 Cables, three phases require 24 400mm cables 2 The number of cables is large, the cables are thicker, and the cost is higher, which makes the cost of the entire wind turbine relatively high.

[0006] In summary, the low-voltage electricity generated by the stator and rotor of the doubly-fed generator in the current system needs to be boosted by a transformer before being connected to the power grid; moreover, the current maximum voltage emitted by the stator is 10.5KW, which is relatively low, resulting in a large current. A large number of cables are used to connect the three-phase winding of the generator stator to the transformer and other equipment. The cables are very thick and costly, making the cost of the entire wind turbine relatively high.

[0007] In view of this, the present invention proposes a 35kV grid-direct-connected double-fed wind turbine generator to overcome the defects of the prior art. Summary of the invention

[0008] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art. The present invention provides a 35kV grid direct-connected doubly-fed wind turbine generator, which has the advantages of large single-machine power, high output voltage, low current, high heat exchange efficiency, high reliability, etc. It can effectively save the cost of step-up transformers, reduce the number of cables of the unit, and effectively reduce the design and manufacturing cost of the entire unit.

[0009] A 35kV grid-direct-connected doubly-fed wind turbine generator of the present invention is provided with a cooling device on its upper part, comprising a stator, a rotor, a bearing unit and a slip ring brush holder system, wherein the stator comprises a stator frame and a stator winding assembly, a rotor is mounted on the stator frame, the rotor is supported and fixed by bearing units arranged at both ends of the stator frame, the stator winding assembly is directly connected to the grid through a stator junction box, and at least one layer of cooling pipes is arranged on the surface of the stator coils at both ends of the stator winding assembly.

[0010] Furthermore, the stator winding assembly is composed of a stator coil and a stator core. After the stator core is embedded in the stator coil, both ends of the stator winding assembly are integrally potted with potting glue.

[0011] Furthermore, the stator coil insulation layer is made of epoxy multi-resin mica tape reinforced with glass cloth and a combination of multi-level anti-corona materials, and a frame-type stator coil is formed through a molding process.

[0012] Furthermore, the cables on the stator junction box are connected using high-voltage cable T-type connectors.

[0013] Furthermore, any one phase of the multi-phase stator cables of the generator has only two cables.

[0014] Furthermore, the cross-sectional area of ​​the cable is 70 mm 2 .

[0015] Furthermore, a cooling medium is introduced into the cooling pipeline.

[0016] Furthermore, the heat generated at the stator winding assembly end is cooled by cold air generated by the cooling device and the cooling medium arranged in the cooling pipe, and the heat generated in the middle of the generator is cooled by cooling water of the air-cooled water cooler in the cooling device.

[0017] Furthermore, one side of the stator frame is connected to a slip ring brush holder system.

[0018] Furthermore, the power grid is a 35kV high-voltage power grid.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The present invention adopts a 35kV high-voltage double-fed wind turbine generator design that is directly connected to the power grid. The stator output voltage of the generator is directly 35kV, and it is directly connected to the power grid for energy transmission, eliminating the transformer;

[0021] 2. The present invention adopts a frame-type stator coil with special insulating materials and a molding process. The 35kV motor stator coil insulation layer adopts a special insulating material. The stator coil insulation adopts a glass cloth reinforced epoxy multi-resin mica tape ground insulation material + low resistance tape + medium resistance tape + high resistance tape multi-level anti-corona structure, and the frame-type stator coil is formed by a molding process;

[0022] 3. After the stator coil of the present invention is embedded in the stator core, the stator winding end is integrally potted with a high thermal conductivity potting glue, and the integrally potted stator winding assembly end anti-corona structure is adopted to solve the problem of corona discharge damage to insulation caused by high voltage;

[0023] 4. The present invention adopts a high-efficiency cooling medium cooling and heat dissipation structure at the stator winding end, arranges dense cooling pipes at the stator winding assembly end, and adopts an integrally potted anti-corona structure at the stator winding assembly end; one or more layers of cooling pipes are densely arranged along the coil surface of the stator winding assembly end according to the spatial size, and a high-efficiency cooling medium is passed into the pipe to take away the heat generated by the stator winding assembly end, thereby playing the role of cooling the end, and the spacing of the cooling pipes is as small as possible;

[0024] 5. The present invention adopts a multi-medium cooling method. The heat generated by the generator is cooled by three cooling media: air, water, and high-efficiency cooling medium, and the cooling efficiency is high;

[0025] 6. The heat generated inside the generator of the present invention is cooled by different cooling media in different areas. In the entire ventilation cooling circuit, the heat generated by the stator winding assembly ends on both sides of the generator is cooled by the air generated by the cooling device and the cooling medium arranged in the cooling pipes densely arranged at the stator winding assembly ends; the heat generated in the middle of the generator is cooled by the cooling water of the air water cooler in the cooling device;

[0026] 7. The present invention adopts a stator junction box connected by a high-voltage cable T-type connector. This structure can greatly reduce the size of the junction box. For example, the stator three-phase cable of a 35kV high-voltage double-fed wind turbine only needs two 70mm cables per phase. 2 Cables, three phases require a total of 6 70mm 2 The number of cables is less and the cost is greatly reduced compared to the original one. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural block diagram of an existing doubly-fed wind turbine generator system;

[0028] Figure 2 Schematic diagram of the existing double-fed generator structure; double-fed generator stator junction box structure

[0029] Figure 3 It is a top view schematic diagram of the stator junction box structure of an existing doubly-fed generator;

[0030] Figure 4 It is a main schematic diagram of the structure of the stator junction box of an existing double-fed generator;

[0031] Figure 5 This is a schematic diagram of the structure of a 35kV grid-direct-connected double-fed wind turbine generator according to the present invention;

[0032] Figure 6 This is a schematic diagram of cooling medium partitioning of a 35kV grid-direct-connected double-fed wind turbine generator of the present invention;

[0033] Figure 7 It is a top view schematic diagram of a 35kV grid direct-connected doubly-fed wind turbine stator junction box of the present invention;

[0034] Figure 8 It is a side view schematic diagram of a 35kV grid direct-connected doubly-fed wind turbine stator junction box of the present invention;

[0035] Fig. 9 It is a front schematic diagram of a stator junction box of a 35kV grid direct-connected doubly-fed wind turbine generator according to the present invention.

[0036] Among them, XY1-wind turbine; XY2-gearbox; XY3-doubly fed wind turbine; XY4-converter; XY5-transformer; XY6-conventional rotor; XY7-conventional stator; XY8-drive end bearing unit; XY9-non-drive end bearing unit; 10-cooling device; 1-power grid; 2-stator winding assembly; 21-cooling pipe; 3-bearing unit; 4-slip ring brush holder system; 5-stator base; 6-rotor; 7-ventilation duct; 8-cooling device; 9-left cooling zone; 10-middle cooling zone; 11-right cooling zone; 12-stator junction box; 121-T-connector; 122-cable. DETAILED DESCRIPTION

[0037] The embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention.

[0038] According to an embodiment of the present invention, referring to the attached Figure 5As shown, the present invention provides a 35kV grid-direct-connected double-fed wind turbine generator, including: a stator, a rotor 6, an end cover unit, a cooling assembly, a bearing unit 3, a slip ring brush holder system 4, etc. Among them, the cooling assembly includes: a cooling device 8 is arranged on the upper part, and a plurality of cooling pipes 21 are arranged at both ends of the stator winding assembly 2. Among them, the stator includes a stator frame 5 and a stator winding assembly 2, and the rotor 6 includes a rotor winding assembly, and the rotor winding assembly is composed of a rotor core and a rotor coil. The rotor 6 is installed on the stator frame 5, and the rotor 6 is supported and fixed by the bearing units 3 arranged at both ends of the stator frame 5. The stator winding assembly 2 is directly connected to the grid 1 through the stator junction box 12. The end cover unit includes a bearing unit 3 and a generator end cover, etc. One side of the stator frame 5 is connected to the slip ring brush holder system 4. The stator output voltage of the generator is directly 35kV, which is directly connected to the power grid 1 for energy transmission, eliminating the transformer. The stator output voltage of the generator is directly 35kV, which is directly connected to the power grid 1, and no additional transformer is required for voltage boosting. In addition, after the transformer is eliminated, the maintenance cost of the transformer is reduced.

[0039] According to an embodiment of the present invention, the bearing unit 3 includes front and rear bearing units assembled together with the stator, respectively located on both sides of the stator, and plays a supporting role for the rotor 6 of the engine.

[0040] According to an embodiment of the present invention, the stator winding assembly 2 is composed of a stator coil and a stator core. After the stator core is embedded in the stator coil, both ends of the stator winding assembly 2 are integrally potted with potting glue, with the purpose of eliminating the air gap and solving the problem of corona discharge damaging insulation caused by high voltage. The process is feasible.

[0041] According to an embodiment of the present invention, the stator coil is made of insulating material and a frame-type stator coil is formed by a molding process. Since high voltage will bring reliability problems such as corona discharge of the winding, very high requirements are placed on the stator coil and the winding insulation structure. Therefore, it is necessary to adopt a special insulation structure to improve the reliability problems caused by high voltage. The stator coil insulation layer used in the present invention is made of a multi-level anti-corona structure of epoxy multi-resin mica tape + low resistance tape + medium resistance tape + high resistance tape reinforced with glass cloth. The use of special insulating materials can ensure that the stator coil has good insulation performance. At the same time, as the power of the generator continues to increase, it will bring problems such as high heat generation and temperature rise. Therefore, it is necessary to adopt efficient cooling technology to reduce the temperature rise of the winding and increase the life of the generator.

[0042] According to an embodiment of the present invention, referring to the attached Figure 6As shown, the cooling device 8 of the present invention adopts an air-water cooler, and the air-water cooler structure includes a cooling fan and a water-cooled core. The present invention adopts a high-efficiency cooling medium cooling and heat dissipation structure at the end of the stator winding assembly 2, that is, dense cooling pipes are arranged at the end of the stator winding assembly 2, and high-efficiency cooling medium is passed through the pipes to take away the heat generated by the end of the stator winding assembly 2, thereby cooling the end. In addition, the generator of the present invention adopts a multi-medium cooling method during use. The heat generated by the generator is cooled by three cooling media: air, water, and high-efficiency cooling medium, and the cooling effect is high. The multi-medium zoning cooling range is divided, including a left cooling zone 9, a middle cooling zone 10, and a right cooling zone 11. The heat generated inside the generator is cooled by different cooling media in different areas. As shown Figure 6 As shown, in the entire ventilation cooling circuit, the heat generated by the ends of the stator winding assembly 2 on both sides of the generator in the left cooling zone 9 and the right cooling zone 11 is cooled by the air generated by the cooling device 8 and the cooling medium in the cooling pipe 21 densely arranged at the ends of the stator winding assembly 2; in the middle cooling zone 10, the heat generated in the middle of the generator is transported to the upper cooling device 8 through the ventilation pipe 7, and the hot air is cooled by the cooling water in the hollow water cooler of the cooling device 8. A high-efficiency cooling medium is introduced into the cooling pipe 21, and specifically, the high-efficiency cooling medium is a cooling fluorinated liquid.

[0043] According to the embodiment of the present invention, one or more layers of cooling pipes 21 are densely arranged along the surface of the stator coil at the end of the stator winding according to the space size, and the distance between adjacent cooling pipes 21 is as small as possible, which can be adjusted according to the actual installation space. In addition, a high-efficiency cooling medium is introduced into the cooling pipe 21 to take away the heat generated by the end of the stator winding assembly 2, thereby playing a role in cooling the end.

[0044] According to an embodiment of the present invention, referring to the attached Figure 7-9 As shown, the cable 122 on the stator junction box 12 is connected by a high-voltage cable T-type connector 121. This structure can greatly reduce the size of the junction box. Specifically, after the two T-type connectors 121 are connected, one end (such as Figure 8 The horizontal end shown in FIG. 1 is connected to the power grid 1, and the other end (as shown in FIG. Figure 8 The vertical end shown in the figure is connected to the stator winding end 2. It can be seen that the stator three-phase cable of the 35kV high-voltage double-fed wind turbine generator only needs two 70mm long cables per phase. 2 Cables, three phases require a total of 6 70mm 2 The number of cables is less and the cost is greatly reduced compared to the original one.

[0045] The present invention provides a 35kV grid-direct-connected doubly-fed wind turbine generator, whose stator directly emits a voltage of 35kV, and a step-up transformer is eliminated on the stator side; the 35kV high voltage electricity emitted by the stator is directly connected to the grid 1; the stator coil insulation adopts a glass cloth-reinforced epoxy multi-resin mica tape ground insulation material + a low, medium and high multi-level anti-corona material structure, and a frame-type stator coil is formed by a molding process; the end of the stator winding assembly 2 adopts an integrally potted anti-corona structure; one or more layers of cooling pipes 21 are densely arranged at the end of the stator winding 2 along the surface of the stator coil according to the spatial size, and a high-efficiency cooling medium is passed into the cooling pipe 21 to take away the heat generated at the end of the stator winding assembly 2, thereby cooling the end; the heat generated by the generator is cooled by three cooling media: air, water and high-efficiency cooling medium, and the cooling effect is good; the heat generated inside the generator is cooled by different cooling media in different areas.

[0046] The present invention provides a 35kV grid-direct-connected double-fed wind turbine generator. The stator emits 35kV high voltage electricity that is directly connected to the grid 1. A step-up transformer is no longer needed on the stator side. At the same time, the voltage increases and the current decreases. For wind turbines with the same power, the number and cost of cables 122 are greatly reduced. The operation is simple and the processability is strong. Its basic structure is basically the same as that of the existing double-fed generator, and it also mainly includes a stator, a rotor 6, an end cover unit, a cooling assembly, a slip ring brush holder system 4, etc. The process is mature and will not be described in detail. The key point is that the requirements for insulation reliability are increased after the voltage is increased. The stator coil adopts a stator frame stator coil with special insulating materials and a molding process to ensure insulation performance. In addition, the end of the stator winding assembly 2 is potted to eliminate the air gap and prevent the problem of corona discharge. The process is feasible.

[0047] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

Claims

1. A 35kV grid-direct-connected double-fed wind turbine generator, with a cooling device (8) disposed on its upper portion, characterized in that: It includes a stator, a rotor, a bearing unit and a slip ring brush holder system (4). The stator comprises a stator frame (5) and a stator winding assembly (2), a rotor (6) being mounted on the stator frame (5), the rotor (6) being supported and fixed by bearing units (3) arranged at both ends of the stator frame (5), the stator winding assembly (2) being directly connected to a power grid (1) via a stator junction box (12), and at least one layer of cooling pipes (21) being arranged along the surface of the stator coil at both ends of the stator winding assembly (2).

2. The 35kV grid-direct-connected doubly-fed wind turbine generator according to claim 1, characterized in that: The stator winding assembly (2) is composed of a stator coil and a stator core. After the stator core is embedded in the stator coil, both ends of the stator winding assembly (2) are integrally potted with potting glue.

3. The 35kV grid-direct-connected doubly-fed wind turbine generator according to claim 2, characterized in that: The stator coil insulation layer is made of epoxy multi-resin mica tape reinforced with glass cloth and a combination of multi-level anti-corona materials, and a frame-type stator coil is formed through a molding process.

4. The 35kV grid-direct-connected doubly-fed wind turbine generator according to claim 1, characterized in that: The cables (122) on the stator connection box (12) are connected using a T-type connector (121).

5. The 35kV grid-direct-connected doubly-fed wind turbine generator according to claim 4, characterized in that: Any one phase of the stator multi-phase cables of the generator has only two cables (122).

6. The 35kV grid-direct-connected doubly-fed wind turbine generator according to claim 5, characterized in that: The cross-sectional area of ​​the cable (122) is 70 mm 2 .

7. The 35kV grid-direct-connected doubly-fed wind turbine generator according to claim 1, characterized in that: A cooling medium is introduced into the cooling pipe (21).

8. The 35kV grid-direct-connected doubly-fed wind turbine generator according to claim 1, characterized in that: The heat generated at the stator winding assembly (2) end is cooled by cold air generated by a cooling device (8) and a cooling medium arranged in a cooling pipe (21), and the heat generated in the middle of the generator is cooled by cooling water in a hollow water cooler of the cooling device (8).

9. The 35kV grid-direct-connected doubly-fed wind turbine generator according to claim 1, characterized in that: One side of the stator frame (5) is connected to the slip ring brush holder system (4).

10. The 35kV grid-direct-connected doubly-fed wind turbine generator according to any one of claims 1 to 9, characterized in that: The power grid (1) is a 35 kV high-voltage power grid.

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