A permanent magnet generator for offshore wind power and its working method

Abstract

The present invention proposes a permanent magnet generator for offshore wind power and an operating method thereof, which comprises at least a stator and a rotor, and is provided with a cooling cavity; the rotor is located outside the cooling cavity, and the stator is located inside the cooling cavity; the cooling cavity is filled with a cooling medium; in the present invention, the stator is entirely immersed in the cooling medium, thereby achieving maintenance-free operation or reduced maintenance frequency of the offshore unit; and the invention is suitable for cooling offshore wind turbines.

Description

Technical Field

[0001] The present invention belongs to the technical field of generator stator cooling, and in particular relates to a permanent magnet generator for offshore wind power and a working method thereof. Background Art

[0002] A wind turbine is an electrical device that converts wind energy into mechanical work, which drives the rotor to rotate and ultimately outputs alternating current. A wind turbine generally consists of a wind wheel, a generator (including a device), a direction regulator (tail wing), a tower, a speed limiting safety mechanism, and an energy storage device. Currently, wind turbines generally use water jacket cooling, air-to-air cooling, and direct air cooling.

[0003] The inventors have discovered that the existing wind turbine cooling method has the following disadvantages:

[0004] 1. Water jacket cooling, air-to-air cooling, and direct air cooling are all used on land on a large scale. The maintenance of onshore generators is relatively easy, but for offshore wind power generation, maintenance and repair are very difficult;

[0005] 2. Water jacket cooling, air-to-air cooling and direct air cooling all require additional power sources, such as electric motors for forced cooling, which not only increases the difficulty of maintenance, increases electric equipment, but also reduces the efficiency of wind power generation. Summary of the Invention

[0006] In order to solve the above-mentioned problems, the present invention proposes a permanent magnet generator for offshore wind power and a working method thereof. In response to the higher technical requirements of offshore wind power generation, the present invention designs a simpler, safer and more efficient generator stator cooling device in order to minimize the frequency of failures and the amount of maintenance. In the present invention, a fluorocarbon compound (such as R113 refrigerant) with low boiling point, high insulation, non-combustible, non-toxic and chemically stable is used as the cooling medium. Through a good mechanical structure design, the stator is completely immersed in the cooling medium, and the self-circulation of the cooling system is realized, thereby realizing maintenance-free operation or reduced maintenance frequency of the offshore unit.

[0007] In order to achieve the above objectives, in a first aspect, the present invention provides a permanent magnet generator for offshore wind power, which adopts the following technical solution:

[0008] A permanent magnet generator for offshore wind power generation comprises at least a stator and a rotor, and is provided with a cooling cavity;

[0009] The rotor is located outside the cooling cavity, and the stator is located inside the cooling cavity; the cooling cavity is filled with a cooling medium.

[0010] Furthermore, the stator includes a stator core, one end of which is connected to a generator base; the generator base is located inside the cooling cavity and immersed in the cooling medium.

[0011] Furthermore, the stator core is elastically connected to the generator frame.

[0012] Furthermore, the stator also includes a stator coil and its end; the cooling medium liquid level is lower than the end surface of the stator core away from one end of the generator base, and higher than the stator coil and its end away from one end of the generator base.

[0013] Furthermore, the housing of the stator is configured as a cage structure.

[0014] Furthermore, the top of the cooling cavity is an inclined surface, with an inlet and an outlet respectively provided at both ends of the inclined surface; an air cooler is provided at the top of the cooling cavity; a first air chamber and a second air chamber are respectively provided at both ends of the air cooler, the first air chamber is connected to the outlet, and the second air chamber is connected to the inlet.

[0015] Furthermore, the volume of the first air chamber is greater than the volume of the second air chamber, and the height of the first air chamber is greater than the height of the second air chamber.

[0016] Furthermore, the air cooler includes a plurality of cooling pipes, and both ends of the cooling pipes are respectively connected to the first air chamber and the second air chamber.

[0017] Furthermore, the cooling medium is a fluorocarbon compound.

[0018] In order to achieve the above-mentioned purpose, in a second aspect, the present invention further provides a method for producing a permanent magnet generator for offshore wind power, which adopts the following technical solution:

[0019] A method for operating a permanent magnet generator for offshore wind power, using the permanent magnet generator for offshore wind power as described in the first aspect, comprising:

[0020] The cooling medium immerses the stator coil, its ends and the stator core to perform heat exchange; the cooling medium, after its temperature rises, runs upward, and the temperature of the liquid near the cooling medium liquid surface increases; the liquid at the cooling medium liquid surface vaporizes and absorbs heat; the vaporized gas enters the first air chamber through the outlet, and enters the cooler from the first air chamber, in the cooler the cooling medium is liquefied from gas to liquid, the liquefied cooling medium flows into the second air chamber, and in turn flows into the cooling cavity from the second air chamber and the inlet.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention immerses the entire stator in a cooling medium, achieving maintenance-free operation or reducing the number of maintenance times for offshore units; and is suitable for cooling offshore wind turbines;

[0023] 2. The stator cage structure of the present invention does not have a stator housing, which not only reduces the weight of the generator stator, but also ensures better heat exchange between the stator core and coil and the cooling medium;

[0024] 3. In the present invention, the entire stator and base are placed in the cooling medium and the FRP cavity, and the elastic mounting structure of the stator cage and the base can prevent the high-frequency vibration generated by the stator from being transmitted to the FRP cavity by the unit, causing damage to the FRP cavity;

[0025] 4. In the present invention, the stator core, stator coil and their ends are immersed in a cooling medium. The space between the stator core, stator coil and their ends is filled with the cooling medium, ensuring sufficient heat exchange. In addition, due to the high insulation properties of the cooling medium, ionization and electrical corrosion of the insulation by the electric field are avoided, thus ensuring the long-term operation reliability of the stator.

[0026] 5. The air cooler in the present invention is placed above the FRP cavity. Taking advantage of the low temperature and good fluidity of offshore wind power air, the air cooler is cooled by the natural flow of air.

[0027] 6. The present invention achieves liquid-gas-liquid self-circulation of the cooling medium through the design of the inlet and outlet, large air cooler chamber, small air cooler chamber, and air cooler structure at the upper part of the cavity. This does not require additional energy, thus saving energy and avoiding downtime and maintenance caused by failure of the forced cooling equipment.

[0028] 7. In the present invention, the cooling medium in the glass cavity is low temperature, medium temperature, and vaporization point from the bottom to the top. The cooling medium is located above the end of the stator coil to ensure that all coil parts are directly cooled. The cooling medium does not completely submerge the iron core, ensuring that a part of the high-temperature iron core plays the role of vaporizing the cooling medium, forming a liquid-gas-liquid cycle with the air cooler, ensuring the safety and timeliness of cooling. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings constituting a part of the specification of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments and descriptions of this embodiment are used to explain this embodiment and do not constitute an improper limitation on this embodiment.

[0030] Figure 1 This is a schematic diagram of the main structure of Example 1 of the present invention;

[0031] Figure 2 Schematic diagram of the side structure of embodiment 1 of the present invention;

[0032] Among them, 1. FRP cavity, 2. rotor, 3. stator core, 4. stator coil and its end, 5. inlet, 6. air cooler chamber, 7. stator cage, 8. elastic connection device, 9. generator base, 10. cavity FRP, 11. outlet, 12. air cooler chamber, 13. air cooler, 14. cooling medium liquid level, 15. FRP cavity top, 16. air cooler, 17. inner cavity FRP, 18. cooling medium. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0035] Example 1:

[0036] like Figure 1 As shown, this embodiment provides a permanent magnet generator for offshore wind power, which includes at least a stator and a rotor 2, and is provided with a cooling cavity;

[0037] The rotor 2 is located outside the cooling cavity, and the stator is located inside the cooling cavity; the cooling cavity is filled with a cooling medium 18;

[0038] In this embodiment, the cooling cavity can be configured as a glass fiber reinforced plastic cavity; Figure 1 and Figure 2 As shown, the FRP cavity 1 is composed of a cavity FRP 10 and an inner cavity FRP 17 to form a closed cooling cavity except for the outlet 11 and the inlet 5 .

[0039] In this embodiment, if Figure 1 As shown, the stator includes a stator core 3, one end of which is connected to a generator frame 9; the generator frame 9 is located inside the cooling cavity and immersed in the cooling medium 18; the stator core 3 and the generator frame 9 are elastically connected, which can be achieved by a spring or by providing an elastic sheet on a bolt.

[0040] The entire stator and the generator base 9 are placed in the cooling medium 11 and the FRP cavity 1, and the stator core 3 is elastically mounted on the stator cage (housing) and the generator base 9 to prevent the high-frequency vibration generated by the stator from being transmitted to the FRP cavity 1 by the unit, causing damage to the FRP cavity.

[0041] In this embodiment, the stator further includes a stator coil and an end portion 4 thereof; the cooling medium liquid level 14 is lower than the end surface of the stator core 3 away from the end of the generator base 9, and higher than the stator coil and the end portion 4 away from the end of the generator base 9; it can be understood that the cooling medium liquid level 14 is higher than the stator coil end portion 4 and lower than the highest point of the stator core 3.

[0042] In this embodiment, the stator shell is configured as a cage structure, and the cage structure is a stator cage 7. The stator cage 7 can be configured as a cage welded by steel pipes. The stator cage 7 is welded to the generator base 9 through an elastic connection device 8 to prevent fatigue damage to the fiberglass reinforced plastics due to high-frequency vibration.

[0043] In this embodiment, the top of the cooling cavity is an inclined surface, with an inlet 5 and an outlet 11 respectively provided at both ends of the inclined surface; an air cooler 13 is provided at the top of the cooling cavity; a first air chamber (large air cooler chamber 12) and a second air chamber (small air cooler chamber 6) are respectively provided at both ends of the air cooler 13, the first air chamber is connected to the outlet 11, and the second air chamber is connected to the inlet 5; the volume of the first air chamber is greater than the volume of the second air chamber, and the height of the first air chamber is greater than the height of the second air chamber; the air cooler 13 includes a plurality of cooling pipes, the ends of the cooling pipes are respectively connected to the first air chamber and the second air chamber;

[0044] The top 15 of the FRP cavity is provided with an inclined surface with one side higher and the other side lower, so as to facilitate the liquid to flow down; the cooling pipe is provided with the same configuration as the top 15 of the FRP cavity, with one end higher and the other end lower, and heat dissipation fins are installed on the outside of the cooling pipe; the first air chamber and the second air chamber serve as two cooling chambers, and are combined with multiple cooling pipes and fins passed through the cooling pipes to form an air cooler.

[0045] In this embodiment, the cooling medium is a fluorocarbon compound, and the fluorocarbon compound can be selected from refrigerants such as R113 as the cooling medium.

[0046] The working principle or process of this embodiment is as follows:

[0047] The heat source of the stator is the stator coil and its end 4 and the stator core 3. The cooling medium 18 immerses the stator coil and its end 4 and the stator core 3 to ensure sufficient heat exchange between the cooling medium 18 and the stator coil and its end 4 and the stator core 3. The cooling medium 18 after the temperature rises will move upward, causing the liquid temperature near the cooling medium liquid surface 14 to be higher. The temperature of the stator core 3 is the highest temperature of the entire generator stator. The cooling medium liquid surface 14 is the main vaporization point, taking away a large amount of energy. The vaporized gas moves upward along the top 15 of the fiberglass cavity, driving the movement of the gas. The outlet 11 of the FRP cavity 1 enters the large air cooler chamber 12, and enters the cooling pipe of the small air cooler cooler 13 from the large air cooler chamber 12. Due to the low temperature outside the cooling pipe, the cooling medium is liquefied from gas to liquid, and the volume of the cooling pipe of the small air cooler cooler 13 is reduced, which accelerates the flow of gas from the small air cooler FRP cavity 1 to the large air cooler chamber 12. The liquefied cooling medium 18 of the cooling pipe of the cooler 13 flows into the small air cooler cooling chamber 6, and flows into the FRP cavity 1 from the small air cooler cooling chamber 6 and the inlet 5 of the small air cooler FRP cavity 1 in turn, thereby completing the entire cycle from liquid to gas and then to liquid.

[0048] When the vaporized cooling medium 18 passes through the cooling pipe of the cooler 13, heat exchange is performed, and the air temperature around the cooling pipe rises, causing air circulation and forming natural cooling, which is suitable for offshore wind power operation.

[0049] Example 2:

[0050] This embodiment further illustrates the offshore wind power permanent magnet generator in embodiment 1; specifically:

[0051] The stator core 3 and the stator coil form an integral whole and are embedded in a steel cage 7 formed by welding steel pipes to form the generator stator. The stator has no stator casing, which not only reduces the weight of the stator but also facilitates heat dissipation of the stator core and coils. The entire stator core, stator coil and stator cage 7 are welded to the generator base through elastic supports formed by steel pipes, which can effectively reduce the high-frequency vibration generated during the operation of the generator from being transmitted to the base, so as to avoid damage to the fiberglass cavity lower seat under the base.

[0052] The entire stator core 3, stator coil, stator cage 7 and generator frame 9 form a whole and are placed in a closed structure made of fiberglass; an air cooler is placed on the upper part of the closed structure, and the air cooler consists of two cooling chambers, multiple cooling pipes and fins inserted on the cooling pipes; during operation, the closed environment composed of fiberglass is injected with cooling medium, and the highest liquid level submerges the end position of the coil; when the motor is running, the heat emitted by the core and coil heats the cooling medium, and the cooling medium liquid near the core that is not immersed in the core accelerates vaporization, and the vaporized gas enters the cooler chamber 12; the cooling pipe of the cooler 13 absorbs the temperature of the vaporized gas, causing the temperature of the cooling pipe to rise, and the air outside the cooling pipe rises, accelerating the flow of air around the cooling pipe and accelerating the cooling of the cooling pipe; due to the temperature drop inside the cooling pipe, the cooling medium changes from gas to liquid, and the liquid flows from the cooling pipe into the cooler chamber 6; the air pressure in the cooling pipe drops, causing the cooler chamber to continuously replenish gas, forming a self-circulation.

[0053] There is no stator casing outside the stator, and the cooling medium in the glass fiber reinforced plastic cavity 1 flows freely and exchanges heat, and the cooling medium liquid fills the air gap around the iron core and the coil, which can fully exchange heat.

[0054] The liquid level is located above the stator end coil but does not submerge all the cores; the liquid level contacts the core with a higher temperature, which is the main vaporization position where the cooling medium changes from liquid to gas, and the temperature becomes lower as the liquid level goes down.

[0055] The top of the fiberglass cavity 1 is a sloped device, which helps the high-temperature gas to flow upward and enter the cooler chamber 12. It helps the gas inside the cooler to liquefy and then flow down along the slope and flow to the air cooler chamber 6 and flow into the upper layer of the liquid surface. After the lower temperature liquid mixes with the higher temperature liquid, it is beneficial to the mixing inside the liquid.

[0056] The fiberglass cavity 1 is located outside the rotor and does not cool the generator rotor.

[0057] The generator stator and the generator frame 9 adopt an elastic support structure to reduce the vibration damage caused by the core vibration to the fiberglass reinforced plastic.

[0058] The silicon steel sheets of the generator are stacked in a stator cage composed of steel pipes, the stator coils are embedded in the stator core, and there is no closed casing outside the stator cage.

[0059] The air cooler 13 is divided into a large air cooler chamber 12, a small air cooler chamber 6, air cooler tubes and air cooler fins. The air cooler 13 is arranged with the large air cooler chamber 12 at a higher position and the small air cooler chamber 6 at a lower position, with one end higher than the other end, to facilitate the reflux of the liquefied liquid; the cooling tube heats the surrounding air, causing the air temperature to rise and flow, which helps to cool the air cooler tube itself, forming self-cooling.

[0060] The internal cooling of the generator is self-circulating, and the cooling medium enters the large air cooler chamber 12 after vaporization. The gas is cooled and liquefied in the cooling pipe, causing the large air cooler chamber 12 to attract more gas to be sucked into the large air cooler chamber 12. The liquid in the cooling pipe flows down the pipe and the liquefaction of the gas in the cooling pipe causes the air pressure in the pipe to drop, causing the gas to enter the large air cooler chamber 12, the gas is liquefied in the cooling pipe, and flows into the small air cooler chamber 6, and the liquid flows into the fiberglass cavity 1, forming a complete cooling cycle.

[0061] Example 1:

[0062] This embodiment provides an operating method of a permanent magnet generator for offshore wind power, which uses the permanent magnet generator for offshore wind power as described in the first aspect, including:

[0063] The cooling medium immerses the stator coil, its ends and the stator core to perform heat exchange; the cooling medium, after its temperature rises, runs upward, and the temperature of the liquid near the cooling medium liquid surface increases; the liquid at the cooling medium liquid surface vaporizes and absorbs heat; the vaporized gas enters the first air chamber through the outlet, and enters the cooler from the first air chamber, in the cooler the cooling medium is liquefied from gas to liquid, the liquefied cooling medium flows into the second air chamber, and in turn flows into the cooling cavity from the second air chamber and the inlet.

[0064] The above description is merely a preferred embodiment of this embodiment and is not intended to limit this embodiment. Those skilled in the art will readily appreciate that this embodiment may be modified and varied in various ways. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this embodiment shall be within the scope of protection of this embodiment.

Claims

1. A permanent magnet generator for offshore wind power, comprising at least a stator and a rotor, characterized in that: Setting a cooling cavity; The rotor is located outside the cooling cavity, and the stator is located inside the cooling cavity; the cooling cavity is filled with a cooling medium; The stator includes a stator core, one end of which is connected to a generator base; the generator base is located inside the cooling cavity and immersed in the cooling medium; The stator further includes a stator coil and its end portion; the cooling medium liquid level is lower than the end surface of the stator core away from the end of the generator frame, and higher than the stator coil and its end portion away from the end of the generator frame; The top of the cooling cavity is an inclined surface, with an inlet and an outlet respectively provided at both ends of the inclined surface; an air cooler is provided at the top of the cooling cavity; a first air chamber and a second air chamber are respectively provided at both ends of the air cooler, the first air chamber is connected to the outlet, and the second air chamber is connected to the inlet; The air cooler includes a plurality of cooling pipes, and both ends of the cooling pipes are respectively communicated with the first air chamber and the second air chamber.

2. A permanent magnet generator for offshore wind power according to claim 1, characterized in that: The stator core is elastically connected to the generator frame.

3. A permanent magnet generator for offshore wind power according to claim 1, characterized in that: The housing of the stator is configured as a cage structure.

4. A permanent magnet generator for offshore wind power according to claim 1, characterized in that: The volume of the first air chamber is greater than that of the second air chamber, and the height of the first air chamber is greater than that of the second air chamber.

5. The permanent magnet generator for offshore wind power according to claim 1, characterized in that: The cooling medium is a fluorocarbon compound.

6. A method for operating a permanent magnet generator for offshore wind power, characterized in that: The offshore wind power permanent magnet generator according to any one of claims 1 to 5 is used, comprising: The cooling medium immerses the stator coil, its ends and the stator core to perform heat exchange; the cooling medium, after its temperature rises, runs upward, and the temperature of the liquid near the cooling medium liquid surface increases; the liquid at the cooling medium liquid surface vaporizes and absorbs heat; the vaporized gas enters the first air chamber through the outlet, and enters the cooler from the first air chamber, in the cooler the cooling medium is liquefied from gas to liquid, the liquefied cooling medium flows into the second air chamber, and in turn flows into the cooling cavity from the second air chamber and the inlet.

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