Wind generator

Abstract

Wind turbines comprising a generator comprising a shaft and a slip ring assembly mounted on the shaft adjacent a housing. The slip ring assembly is mounted on the shaft and comprises at least one power ring or ground ring disposed at an end of the slip ring assembly adjacent the housing. The ground ring and power ring each comprise an outer perimeter; an inner perimeter; and interface surface therebetween. The power ring or ground ring comprises at least two separatable components that enable the at least one ground ring or power ring to be separately replaceable from around the shaft, and wherein the at least one power ring or ground ring is mounted on the shaft with a plurality of fastening pins. The fastening pins comprise a length less than a gap between the ground ring or power ring and a nearest power ring or ground ring or the housing.

Description

WIND GENERATORFIELD

[0001] This disclosure relates to wind generators which comprise parts which are replaceable without the need for substantial disassembly of the slip ring assembly. More specifically, the disclosure relates to replaceable components of the slip ring assembly and the method of replacing these components.BACKGROUND

[0002] Wind turbines are unmanned as it is unsafe to enter the turbine when it is in operation. Wind turbines are intended to run all day, every day. Thus, there are no personnel to check the day to day running of wind turbines, and wind turbine generators are required to operate with higher reliability than other induction generators. Moreover, wind turbines are often located in remote inaccessible locations where maintenance is expensive due to the cost of safely transporting trained personnel to the wind turbines and the time taken to do so. If wind turbines are located in offshore wind farms, maintenance difficulties are exacerbated whilst operating in hostile environments. Wind turbines typically have a scheduled maintenance programme, and any additional maintenance is highly undesirable as it is estimated to double the cost of scheduled maintenance.

[0003] Whether scheduled maintenance or the response to a generator failure, the ability to service and replace parts safely and efficiently (i.e. with reduced downtime) in a restricted space is of great importance.

[0004] Wind turbines generally use a three-phase asynchronous induction generator to convert mechanical power from rotation of the wind turbine blades into electrical power. The generator comprises a stator and an electrical rotor arranged in a housing, and a slip ring assembly which is mounted on the rotor shaft and connected to the rotor windings to transfer current between the electrical rotor and a frequency converter. The slip ring assembly comprises contact rings mounted on the electrical rotor, which rotate over static slip ring brushes mounted in a slip ring housing to provide a rotating electrical contact.

[0005] Slip ring assemblies typically comprise one or more power rings, and typically three power rings (for three phase power generation), and are employed as part of a fixed assembly that also integrally includes a ground ring. The ground ring serves to ground flux or stray current induced during power generation. The power rings and the ground ring, in particular, are usually the components that deteriorates most rapidly, which can bedue, in part, to electrical erosion that causes pitting. Because the power and ground rings are an integral part of existing slip ring assemblies, the entire assembly, including the power rings, the ground ring, and a hub to which they are affixed, must be replaced. As conventional slip ring assemblies are integrally molded together, and often shrink-fit together, attempting to remove the power or ground rings from an existing slip ring assembly is impractical, if not impossible, and, if attempted, generally causes damage to the slip ring assembly. This situation causes significant waste in material and time as the entire assembly has to be hoisted down from the heights of a wind turbine and then an entire replacement assembly hoisted back up. Operators and maintenance crews can be put at unnecessary risk in these replacement exercises.

[0006] Therefore, there is a need for a wind generator which is configured to enable power or ground rings to the replaceable without the need to replace the entire slip ring assembly. Furthermore, the replacement of the power and ground rings should be able to be conducted in a confined space, particularly in wind turbines comprising stream-line cases (i.e. a nacelle).SUMMARY

[0007] In a first aspect of the present disclosure, there is provided a wind turbine comprising a generator comprising a shaft; and a slip ring assembly mounted on the shaft adjacent a housing, wherein the slip ring assembly is mounted on the shaft and comprises at least one power ring or ground ring; said ground ring, if present, is disposed at an end of the slip ring assembly adjacent the housing; the ground ring and power ring each comprise an outer perimeter; an inner perimeter; and at least one interface surface between the outer and inner perimeters; wherein the at least one power ring or ground ring comprises least two separatable components each which enable the at least one ground ring or power ring to be separately replaceable from around the shaft, and wherein the at least one power ring or ground ring is mounted on the shaft with a plurality of fastening pins, said fastening pins comprising a length less than a gap between the at least one ground ring or power ring and (i) a nearest power ring or ground ring; or (ii) the housing.

[0008] The plurality of fastening pins may mount the at least one ground or power ring to the shaft by connecting said ring(s) to the slip ring assembly. In one embodiment, the plurality of fastening pins connects the ground ring to a mounting plate which is mounted on the shaft, which forms part of, or is separate from, the slip ring assembly.

[0009] The wind turbines of the present disclosure enable the consumable components of ground and power rings to be replaced without having to remove and reinstall the whole slip ring assembly, thereby saving time, money and enhancing safety. The replaceable ground and / or power rings of the present disclosure may be readily removed and replaced by maintenance staff within confined work environments. By specifying the dimensions of the separable components to align with the dimensions of the slip ring assembly or positioning of the slip ring assembly relative to the housing, the separable ground and / or power ring components may be efficiently and conveniently removed and re-attached. The customisation of a fastening tool connecting device to remove and reattach the fastening pins further enhances the commercial benefits of the disclosure.Wind Turbines and Generators

[0010] The wind turbines of the present disclosure encompass a variety of difference wind turbine platforms with a variety of generators. The combination of different commercially available wind turbine platforms combined with difference commercially available generators results in a variety of dimensions and clearances between components within the wind turbine housing. The wind turbine housing typically comprises the slip ring assembly and the generator, which may be enclosed within its own housing. Commercially available equipment is available from General Electric, Winergy, Vestas, Gamesa-Canterey and Acciona-lndar, amongst others. In some embodiments the wind turbine components are housed within a nacelle.Slip Ring Assembly

[0011] In one embodiment, the slip ring assembly comprises at least one power ring and at least one ground ring. In a preferred embodiment, the slip ring assembly comprises three power rings and one ground ring.

[0012] The slip ring assembly of the present disclosure is preferably of a molded design. In other words, the slip ring assembly of the present disclosure is preferably not a built-up assembly, which typically is held together by several screws or other attachment devices which connect together the various components of the slip ring assembly. With a molded design, the components of the slip ring assembly, but for the replaceable ground ring or power ring(s), is permanently or substantially permanently affixed to a hub.

[0013] In some embodiments, ground ring is connected to the shaft separately from the power rings. For example, the power rings may be connected to the shaft via a hub (part of the power ring sub-assembly) mounted onto the shaft, while the ground ring may be connected to the shaft via a mounting plate.

[0014] In some embodiments, the slip ring assembly comprises a power ring subassembly comprising at least one power ring and a hub, where the at least one power ring is connected to the hub, said hub mounted on the shaft. The slip ring assembly may further comprise a ground ring. The ground ring may be connected to a mounting plate.

[0015] The ground ring mounting plate may be directly fixed to the shaft via a keyway (i.e. part of a keyed joint used to connect a rotating machine element to a shaft); an interference fit or other mechanical means. Alternatively, the ground ring mounting plate may be connected (e.g. bolted) to the hub of the power ring sub-assembly.

[0016] The slip ring assembly typically abuts the generator housing and / or bearing couplings or in some lay-out the slip ring assembly abut housing for the slip ring assembly itself. For the purposes of the present disclosure, the housing is inclusive of any housing or bearing couplings which may also restrict access to the ground ring from the generator side. The distance between the housing at the ground ring may vary depending upon the specific lay-out of the wind turbine. In some embodiments, the gap between the housing and the ground ring is such that it is not possible to remove any fastening pins from the generator side of the slip ring assembly. However, in other embodiments, the gap between the slip ring assembly and the housing is sufficient for the fastening pins to be removed. By sufficient, the distance between the closest of the ground ring or mounting plate and the housing is such that the fastening pins comprise a length less than 90% or less than 80% or less than 70% or less than 60% or less than 50% or less than 45% or less than 40% of the gap between the ground ring and the housing. In embodiments, in which the fastening pin may be removed from the generator side, the distance between the housing and the ground ring or mounting plate is between 30 mm and 100 mm or between 40 mm and 85 mm or between 45 mm and 80 mm.

[0017] The slip ring assembly may include at least one power ring affixed to a hub and at least one ground ring mounted on the hub, wherein the power or ground ring is separately replaceable. The slip ring assembly is in cooperation with an armature, and without having to replace the power ring or hub or both. In embodiments in which the power ring is not separable, the power ring and hub of the slip ring assembly can constitute a moulded sub-assembly. The moulded sub-assembly can be shrink-fit.

[0018] In other embodiments, the power ring may form a moulded sub-assembly, whilst the ground ring is separately connected to the shaft.

[0019] Slip ring assembling lengths typically range from 150 to 550 mm, while the outside diameter of the power and ground rings typically range from 120 to 420 mm.

[0020] In one embodiment, the ground ring is replaceable and the gap between the ground ring and the nearest power ring is greater than the gap between the ground ring and the housing (e.g. at least 10% or at least 20% greater). As the slip ring assembly is typically manufactured as a single unit, then the distance between the ground ring and the power ring will remain the same, whereas the distance between the ground ring and generator housing may vary depending upon the specific design of the wind turbine. As such, it is advantageous to design the slip ring assembly such that one, both or all of the ground and power rings may be replaced based upon the slip ring assembly’s internal dimensions.

[0021] A fastening pin can be built-in and / or structurally contiguous with the separable components of the power or ground ring, the slip ring sub-assembly, or both. The fastening pin may include at least one component that is separable from at least one of the sub-assembly, hub, mounting plate, and ground ring. The fastening pin may include an adhesive. The fastening pin may contain at least one magnetic material. The at least one fastening pin may comprise a screw, a bolt, a pin, or any combination thereof.

[0022] In some embodiments, the fastening pin comprises a head portion and a body portion, where in the head portion comprises a larger diameter than the body portion. In other embodiments, the fastening pin may comprise a constant diameter along its length. The fastening pin may be partially or fully embedded in the ring component and the mounting plate.

[0023] The fastening pins attach the replaceable power or ground ring to the hub. This is typically achieved through each of the separatable components of the ring comprising a plurality of apertures in the interface surface of the ring. The hub may comprise correspondingly aligned apertures to enable the fastening pins to be positioned through the apertures in the ring and hub.

[0024] In a preferred embodiment, the fastening pin and receiving apertures in the ring and hub have interlocking threaded surfaces. This enables the fastening pin to be screwed in or otherwise penetrate into the aperture through rotation of the fastening pin. The ability to use rotational motion to insert and remove the fastening pin means than engagement tool used to insert and remove the fastening pin can be designed such that an engagement head of the tool which interfaces with an end of the fastening pin can be design to have minimal dimensions in the axial direction of the fastening pin to therebyenable the engagement tool to be more easily manoeuvred between the gap between the rings (e.g. ground ring and power ring; or power ring and power ring).

[0025] The skilled artisan could also conceive other means of attaching the fastening pin to the hub, including, for example, the fastening pin may comprise an engagement interface at the end which is inserted into the hub, with the engagement interface activating a spring mechanism to lock in the fastening pin. Whilst this method may be convenient to insert the pins, the mechanism to remove the fastening pin for replacement may be more tedious, with the spring locking mechanism being required to be released. Further the complexity of such a mechanism may result in potential failing of the fastening mechanism, leading to the need to replace further components of the slip ring assembly. As such, the simplicity of the threaded fastening pin is preferred.

[0026] The fastening pin may comprise an engagement surface at one end for engagement to the engagement tool. Typically, the engagement surface may comprise a cavity and / or a protrusion, typically with angular sides, such as a hexagon, with the engagement tool comprising a complimentary engagement surface to enable locking engagement with the fastening pin. The engagement surface of the fastening pin is preferably a cavity, such that the fastening pin can be more readily countersunk into the interface surface of the ring.

[0027] In some embodiments, the fastening pins comprise a length less than 90% or less than 80% or less than 70% or less than 60% or less than 50% or less than 45% or less than 40% of the gap between the ground or power ring and the nearest (e.g neighbouring) power ring or housing, from which the fastening pins are extracted towards (or attached from). The larger the gap relative to the length of the fastening pin the more easily the fastening pin can be attached and removed from the hub.

[0028] In some embodiments, the fastening pins have a length in the range of 15 mm to 60 mm and preferably less than 50 mm or less than 45 mm or less than 40 mm or less than 35 mm or less than 30 mm or less than 28 mm or less than 26 mm or less than 24 mm or less than 22 mm.

[0029] The fastening pins typically have a diameter (excluding the head portion) in the range of 5 mm to 25 mm or 8 mm to 20 mm or 10 mm to 18 mm. The thread depth may vary depending upon the other dimensions, but is typically in the range of 1.0 to 2.0 mm.

[0030] The fastening pins are preferably evenly distributed radially around the ring. In some embodiments, each separable component comprises at least two fastening pins or at least three fastening pins or at least 4 fastening pins. In embodiments, where thereare two separable components, each component may comprise three fastening pins. In embodiments, comprising three separable components, each component may comprise two or three fastening pins.Hub

[0031] The hub may include an interface surface complimentary in shape to an interface surface of the ground ring. The hub can optionally include a mounting plate complementary in shape to an interface surface of the power or ground ring. The hub, mounting plate, sub-assembly, or any combination thereof, can have a tapered design that receives the ground or power ring to provide a tapered fit. Interface surfaces can be continuous or discontinuous with one another. At least one of the surfaces can have a curvature with an axis perpendicular to the axis of rotation. The surface curvature can be concave, convex, or any combination thereof. The interface surfaces of the hub, including a mounting plate may be so shaped to allow easy adjoining of a power or ground ring with a complementary shape. The ground ring can contain one or more sub-assembly interface surfaces. The power ring assembly interface surface can be tapered, curved, substantially flat, contoured or any suitable shape that allows connection to the slip ring assembly. The power or ground ring, sub-assembly, or both can include a tongue, groove, or both, on at least one surface.

[0032] In one embodiment, the hub may further comprise at least one mounting plate (or plate) radially extending from the hub, said mounting plate comprising an attachment point from which to attach the power or mounting plate. The hub or mounting plate thereof may comprise attachment points (e.g. apertures) to accept the fastening pins. The mounting plate preferably extends radially outwards to a radius less than the radius of the ground or power ring from the hub, such that the mounting plate is not in engagement with the carbon brushes in operation. The thickness of the combined mounting plate and replaceable ground or power ring is preferably substantially constant in the radial direction from the shaft.Ground or Power Ring

[0033] At least one of the ground ring and the power ring is separable. In some embodiments, the ground ring is separable and replaceable from the slip ring assembly. In some embodiments, one or more power rings is separable and replaceable from the slip ring assembly. In some embodiments, a ground ring and at least one power ring is separable and replaceable from the slip ring assembly. Unless otherwise specified, reference to a ground or a power ring will be taken as reference to a separable andreplaceable ground or power ring. It will also be understood, within context, that aspects of the ground or power ring not related to their separability replaceability, may relate to both separable and fixed ground or power rings.

[0034] The power or ground ring can constitute a single, or multilayered structure, or both. The conductive power or ground ring can include or made of any suitable conductor. The conductor can contain metallic material, non-metallic material, or both. The conductive material can contain or be at least one metal. Examples of suitable metals include copper, aluminium, tin, zinc, bronze, brass, silver, gold, platinum, palladium, tungsten, titanium, tantalum, cobalt, chromium, manganese, nickel, iron, any steel, any alloy thereof, or any combination thereof. The steel can be of any alloy. The steel can be a low carbon steel. The steel can be any stainless steel. Examples of stainless steel types include austenitic, ferritic, martensitic, and duplex stainless steels. The stainless steel can be 410 stainless steel or 416 Martensitic stainless steel. Stainless steel grades of series 200, 300, 400, 600, or any combination thereof can be employed.

[0035] In one embodiment, the power ring comprises a plurality of cooling holes. The cooling holes enable air to circulate around the power rings and assists with the cooling of the power rings by convection. The cooling holes also assist in reducing the weight of the slip ring assembly. In a further embodiment, the cooling rings of the power ring are aligned to the fastening pins apertures of neighbouring power ring or ground ring. With the cooling holes being aligned to the fastening pin position, an engagement tool may be able to be manoeuvred through the aligned cooling hole to remove and reattach the fastening pin. This enables the engagement tool to apply a greater leverage force to more efficiently be able to remove the fastening pins as well are tightly re-securing them.

[0036] The replaceable ground or power ring can may be mounted on or otherwise connected to the molded sub-assembly, but need not be part of the sub-assembly. The slip ring assembly, and the sub-assembly, may include one or more power (slip) rings. One or more or all of the power rings may be replaceable. In one embodiment, three rings can be provided for three-phase power generation. The slip ring assembly can include at least one brush (e.g. carbon brush) in electromechanical association with the at least one power ring. One or more power rings are insulated from the hub using any suitable insulating material. Examples of suitable insulators include a plastic, a rubber, a composite, a glass, a ceramic, or any combination thereof.

[0037] The shape of the power or ground ring can be any functional shape; examples include circular, elliptical, curvilinear, square, rectilinear, polygonal, contoured, undulating, toothed, spiraled, and threaded shapes. The power or ground ring can be inthe shape of a flat annulus, a tapered ring, a torus, or any combination thereof. The inner perimeter surface and the outer perimeter surface can be substantially flat with a circular cross-section in a plane perpendicular to the axis of rotation. At least one of the outer and inner perimeters of the ground ring can be a circumference coaxial to an axis of rotation of the power or ground ring and the slip ring sub-assembly.

[0038] The power or ground ring are provided in separable components, such that the components can be removed from around the generator shaft. In one embodiment, the power or ground rings are provided as two equal halves. This arrangement enables the components to be more easily rotationally balanced. However, other divisions of the rings are possible. The number of ring components are preferably no more than 4 and preferably no more than 3 or no more than 2.

[0039] In one embodiment, the surfaces of the separable components comprise an interface surface with the other separable components making up the ring. The interface surface may be planar or the interface surface may comprise complementary engagement features to inter-lock the separable component to enable the separable components to be more easily aligned with the corresponding apertures on the hub.

[0040] In one embodiment, the thickness of the inner perimeter of the ring is less than thickness of the outer perimeter or the ring (e.g. between 35% and 65% of the thickness of the outer ring). The interface surface of the ring may comprise one or more step changes in thickness between the inner and outer perimeter. The thickness of the replaceable ground or power ring immediately adjacent the fastening pins may be less than the thickness of the replaceable ground or power ring at the peripheral radial surface of the ring in operable contact with the carbon brushes when the generator is in operation. In one embodiment, the length of the fastening pin is less than the thickness of the outer perimeter ( e.g. peripheral radial surface) of the ring. In some embodiments, the fastening pin is in the range of 50% to 100%; or 60% to 95%; or 65% to 90%; or 70% to 85% of the thickness of the outer perimeter of the ring (i.e. power or ground ring which the fastening pin is attached to). Fastening pin lengths less than this range may not be securely attach the ground or power ring to the mounting plate, whilst longer fastening pins may make the removal and attachment of the fastening pin more difficult or even impossible.

[0041] In some embodiment, the spacing between the ground ring and the closest power ring is in the range of 35 mm to 80 mm and preferably less than 70 mm or less than 60 mm or less than 55 mm or less than 50 mm or less than 48 mm or less than 46 mm.

[0042] In some embodiments, the spacing between adjacent power rings is in the range of 40 mm to 120 mm and preferably less than 110 mm or less than 100 mm or less than 90 mm or less than 80 mm or less than 75 mm or less than 70 mm or less than 65 mm.

[0043] In one embodiment, the ground or power ring consists of two or three separatable components (not including the fastening pins). The fewer the number of separable components the less probability of surface variations on the outer perimeter and hence less probability of arcing events due to surface variations.Alignment device

[0044] The ground ring, the slip ring assembly, the hub, and a mounting plate, can include at least one alignment device. The alignment device functions to readily align the separably components of the slip ring assembly to the slip ring assembly. This enables a more efficient removal and re-attachment process as the separable component may be more quickly aligned to the slip ring assembly attachment point (e.g. mounting plate), with the use of an alignment device. In one embodiment, the interface surface of the ground or power ring comprises a radial tongue or radial groove which matches up to an aligned complementary radial groove or radial tongue on the interface surface of the mounting plate. Preferably, the radial groove and radial tongue are tapered such that the radial groove is narrowest at the base of the groove and widest at the opening. This arrangement enables the ring to more readily align with the hub, including the mounting plate.

[0045] In one embodiment, an interface surface of the power or ground ring facing a mounting plate comprises a first planar surface extending at right angles from the outer perimeter towards the inner perimeter; a second planar surface extending from the first planar surface towards the mounting plate; a third planar surface extending from the second planar surface in a parallel direction to the first planar surface with the distance between the third planar surface and an opposing surface representing between 35% and 65% of the thickness of the outer perimeter of the ring; said third planar surface comprising an aperture for a fastening pin; a concave or convex surface feature; and a fourth planar surface extending from the concave or convex segment parallel to the third planar surface.

[0046] The fourth planar surface preferably extends to the inner perimeter of the ring. Typically, the third planar surface is longer than the fourth planar surface. This configuration enables the aperture for the fastening pin to be sufficiently spaced from the concave segment, such to not compromise the mechanical integrity of the fitting. Theconfiguration also enables the fastening pin to be connected to a sufficient portion of each of the ring and the mounting plate to provide a secure attachment. In one embodiment, the ring comprises a concave or convex segment between the third and fourth planar segments. In some embodiments, the concave or convex segments taper in dimension with the middle of the concave or convex segments comprising a smaller effective diameter than the effective diameter of the outer perimeter of the concave or convex segment.

[0047] The engagement tool may also include the alignment device. The alignment device may include a centering pin, a centering pin aperture, an interlockable tooth array, or any combination thereof.Interface aid

[0048] The slip ring assembly can have an interface aid between the ground or power ring and hub or other component of the slip ring assembly. For example, the interface aid may can include a gasket, an o-ring, conductive paste, plating, or any combination thereof. The interface aid is preferably conductive. In one embodiment, one or more of the separatable components of the ring; the interface surface of ring and the interface surface of the mounting plate are coated with a conductive paste to enhance conductive contact within the ring and between the ring and the hub or other contact components of the slip ring assembly.Jacking hole

[0049] As the replaceable power or ground ring may in use several years before being replaced, the ring may be “friction locked” or otherwise adhered to the hub. The high degree of friction between the ring and the hub may be due to the formation of thin films which adhere the surfaces together. The thin films may be composed of a combination of various components including, corroded components, carbon dust from the carbon brushes and vaporised lubricant. The leverage of the engagement tool to remove the fastening pin may not be sufficient to separate the ring from the hub.

[0050] To avoid this situation, the replaceable ring preferably comprises at least one jacking hole. Preferably, each separable component comprises at least one jacking hole. The jacking hole may be located in the interface surface adjacent the fastening pin apertures. The end of the jacking hole should align within a solid surface of the hub (e.g. an interface surface of the mounting plate).

[0051] Once, the fastening pins have been removed, a jacking pin is inserted into the jacking hole and driven against the solid surface of the hub to thereby separate the ring component from the hub. The jacking hole and pin may be threaded to enable an engagement device (preferably the same as that used for the fastening pin) to screw in the jacking pin against the hub. Depending upon the position and diameter of the jacking hole, the jacking pin may be a non-threated bolt with a hammer used to force the end of the jacking pin against the hub to thereby separate the ring component.

[0052] The jacking hole may be smaller, larger or the same diameter of the fastening pin apertures.Replacement Kit

[0053] In a second aspect of the present disclosure, there is provided a replacement kit for a replacement of a ground ring or power ring from the slip ring assembly of the wind turbine according to the first aspect of the present disclosure, comprising:

[0054] At least two separable replacement components which enable the one or both of the ground ring and power ring to be separately replaced from around the generator shaft;

[0055] A fastening pin connecting device for removing and re-attaching a fastening pin comprising: i. A head portion comprising a surface engagement tool for locking engagement with a surface fixture of the fastening pin; and b. A handle portion for at least performing a moving action to unfasten the pin from the ground ring or power ring,

[0056] wherein the head portion is able to fit (i) in the gap between the power or ground ring and the nearest power ring; (ii) in the gap between the ground ring and the generator housing; or (iii) wherein the handle portion is able to fit through a cooling hole of an adjacent power ring to engage and remove the fastening pin from the power or ground ring.

[0057] The fastening pin connecting device may include an Allen key or a ratchet.

[0058] In one embodiment, the sum of the length of the fastening pin and a component of the fastening pin connecting device (e.g. head + part of the handle) along the same axis as the fastening pin, when in interlocking engagement (Ls), is less than the (i) gap between the power or ground ring and the nearest power ring; or (ii) in the gap betweenthe ground ring and the generator housing. Preferably, Ls comprising less than 100% or not more than 95% or no more than 90% or no more than 85% or no more than 80% of the said gaps (i or ii).

[0059] The handle portion may comprise a first component aligned along the same axis as the fastening pin, when the head portion is engaged thereto. The handle portion may also comprise a second component which is orientated along an axis between an angle of 60° to 120° (preferably 80° to 100° or approximately 90°) to the axis of the fastening pin. The orientation of the second component enables the handle to be able to be moved more freely outsides the confines of the slip ring assembly. The handle portion may be “L” or “J” shaped.

[0060] In the embodiment in which the handle portion is able to fit through the cooling hole, then the length of the handle portion and head portion along the axis of the fastening pin is sufficiently long to reach and remove an attached fastening pin(s).Within this embodiment, if the head portion is not able to fit through the cooling hole of an adjacent power ring, then the head portion may be detachable from the handle portion, such that the handle portion may be first positioned through the cooling hole before the detachable head portion is attached to the fastening pin connecting device.

[0061] In a third aspect of the present disclosure there is provided a method of replacing a power or ground ring from a slip ring assembly within a wind turbine according to the first aspect of the present disclosure comprising:

[0062] Engaging the surface engagement tool of the second aspect of the present disclosure with a surface engagement feature of the fastening pin;

[0063] Moving the handle portion of the fastening pin connecting device to facilitate the release of the fastening pin from the power or ground ring;

[0064] Repeating said procedure on each of the remaining fastening pins until all of the fastening pins have been removed;

[0065] Removing each of the components of the power or ground ring from the hub;

[0066] Replacing each of the components of the power or ground rings with new or refurbished power or ground rings; and

[0067] Using the fastening pin connecting device to attach the replaced components with a plurality of fastening pins,

[0068] wherein the surface engagement tool is able to fit (i) in the gap between the power or ground ring and the nearest power ring; (ii) in the gap between the ground ring and a housing; or (iii) through the gap between a cooling hole of an adjacent power ring to engage and remove and / or re-attach the fastening pin from the power or ground ring.

[0069] The lay-out of the wind turbine is required to enable a person to physically access the slip ring assembly and operate said fastening pin connecting device within the confined space of the wind turbine. The fastening pins and fastening pin connecting device are required to be transportable to and from an access port in the turbine housing to the position of removing and replacing the rings and fastening pins. Therefore, the replacement kits components and a person’s body parts (e.g. hands and arms) must be able to navigate through or around turbine components and housing to reach the targeted zone.

[0070] The moving of the fastening pin connecting device is typically a rotating movement, however through mechanisms in the head portions, the handle movement may comprise linear movements (e.g. up and down), with the mechanisms in the head portion converting such movement to rotational movement to unthread the fastening pin from the threaded apertures.

[0071] In one embodiment, the surface engagement tool is interfaced with a jacking pin placed into a jacking hole of the power or ground ring, such a motion of the jacking pin against the mounting plate separates the unfastened power or ground ring from the mounting plate. The jacking hole may be threaded or unthreaded. The jacking hole may be larger, smaller or the same diameter as the aperture for receiving the fastening pin.

[0072] In a fourth aspect of the present disclosure, there is provided a slip ring assembly as defined in the previous aspects of the present disclosure. In particular, the fourth aspect of the present disclosure provides a slip assembly for a wind turbine comprising at least one power ring or at least one ground ring mounted on a hub; the ground ring and power ring comprise an outer perimeter; an inner perimeter; and at least one interface surface between the outer and inner perimeters; wherein at least one of the power or ground rings comprises least two separatable components each which enable at least one of the ground or power ring to be separately replaceable from around the hub, and wherein at least one of the power and ground ring is each mounted on the hub with a plurality of fastening pins, said fastening pins comprising a length less than a gap between the ground or the power ring; and the nearest power or ground ring.

[0073] Reference to ring shall be inclusive of one or both of the ground ring and the power ring(s).

[0074] Reference to a neighbouring power ring is the same as reference to the nearest power ring.

[0075] The terms mount, connect and attach may be used interchangeably.

[0076] Reference to mounting, connecting and attaching may be reference to indirect or direct mounting, connecting or attaching.BRIEF DESCRIPTION OF THE FIGURES

[0077] Figure 1 is a diagram illustrating an outline configuration of a wind power generator according to a first embodiment of the present disclosure.

[0078] Figure 2 is a schematic diagram of components with the nacelle of the wind turbine.

[0079] Figure 3 is a perspective drawing of a slip ring assembling (including carbon brushes) of the present disclosure.

[0080] Figure 4 is a perspective drawing of a slip ring assembly from the power ring side of the present disclosure with an exploded view of the separable ground ring components.

[0081] Figure 5 is a perspective drawing from the ground ring side of the slip ring assembly of Figure 4.

[0082] Figure 6 is a perspective drawing from the ground ring side of the slip ring assembly of Figure 5 without the ground ring components attached to the mounting plate.

[0083] Figure 7 is a top-down view drawing of the slip ring assembly of Figure 4.

[0084] Figure 8 is a cross-sectional view of the drawing of the slip ring assembly of Figure 6 also displaying the outline of a fastening pin connecting device of the present disclosure.

[0085] Figure 9A to 9D are front and rear perspective view, a front view and a side cross- sectional view of a mounting plate component of slip ring assembly, respectively.

[0086] Figure 10A to 10C are front and rear perspective view, and a side cross-sectional view of a ground ring component of slip ring assembly respectively.DETAILED DESCRIPTION

[0087] With reference to Figure 1 , a wind power generator 1 according to the present disclosure is roughly configured so that a nacelle 3 is located on an upper portion of a support rod 2, and a rotor head 4 having wind turbine blades 5 fitted thereto is rotatably supported to a front end side of the nacelle 3.

[0088] As illustrated in Figure 2, in an interior of the nacelle (i.e. stream lined casing) 3 are installed a main shaft 6 that is coupled with the rotor head 4 so as to rotate integrally, a gear box 7 that is coupled with the main shaft 6 which rotates while the wind turbine blades 5 receive a wind power, and a power generator 11 having a generator 8 driven by a shaft output of the gear box 7, and a brush 9 and a slip ring assembly 10A which are disposed inside a housing 34. The rotor head 4 may also include a separate housing. A ventilation fan 12 is located at an appropriate portion inside of the nacelle 3, and the ventilation fan 12 is driven to discharge an external air introduced from an inlet 31 formed in a front end of the nacelle 3 from an outlet 32 communicating with a fan exit to an external of the nacelle 3 to ventilate and cool the interior of the nacelle 3.

[0089] In one embodiment, a humidity management device including a humidifier 13 and a dehumidifier 14 is located in the vicinity of the brush 9 and the slip ring assembly 10A inside of the nacelle 3 (inside of the housing 34), and humidity inside of the power generator 11 having the brush 9 and the slip ring assembly 10A is optionally controlled by the humidity management device including the humidifier 13 and the dehumidifier 14. The additional atmospheric control measures and instruments further make access to the power and ground rings difficult.

[0090] The ground ring typically terminates the end of the slip ring assembly which faces the generator 8. Due to space constraints, access to the ground ring from the generator side is often limited and, in many cases, is inaccessibly without at least partial disassembly of the housing or slip ring assembly.

[0091] With reference to Figures 3 to 6, the slip ring assembly includes three power rings 10, 20 and 30 that are press fit to the hub 80. Figure 3 also illustrates the position of the carbon / graphene brushes 200 relative to the slip ring assembly. The three slip rings are isolated electrically but connected mechanically by six connecting rods 82, 84, 86 which are insulated. The six rods come in three pairs, each pair a different length. One pair of connecting rods 82 is long enough (e.g. 92.75 mm), to reach the power ring 10, another pair of connecting rods 84 is a little longer (e.g. 223.75 mm) to reach the power ring 20, and the last pair of connecting rods 86 is long enough (e.g. 354.75 mm) to reach thepower ring 30. Insulation on them prevents catastrophic flashovers. The ground ring 40, protects bearings from stray electrical currents to prevent electrical damage.

[0092] The slip ring assembly rotates with the generator shaft 6. A set of stationary carbon / graphene brushes 200, one for each of the three rings, picks up the current from the turning slip rings and sends it to the transformer. (The three rings let the slip ring transfer three-phase power.) Additional carbon brushes may be circumferentially placed around each of the power rings 10, 20, 30, and ground rings 40, 50. A mounting plate, 60, is also pressed onto the hub, from which multiple segments of a ring, 40 and 50, are attached via and tongue and groove fit for centering and maintaining concentricity. Three threaded fastening pins per ring segment, 70, helps locate and secure the ring segments to the mounting plate 60. The outside diameter of the ring maintains contact with vertical stationary brushes to transfer current (power) in the radial direction, brushes can be located 360° around the ring. Embodiments of the disclosure of the split ring design and attachment mechanism can be used for both power and ground rings. In other embodiments, some or all of the power rings may be mounted to the hub through an attachment means to a mounting plate, similar to that used to attach the ground ring.

[0093] The outer surface of the power rings 10, 20 and 30 have an optional spiral groove machined into their outer surface. The grooves are typically as wide as the carbon brushes. With the proper pitch to the spiral groove, the surface area of the slip ring remains constant as the air gap rotates under the brush faces. This is important as it maintains a constant brush pressure and a constant amperage per square inch of carbon brush touching the slip ring surface.

[0094] The power rings have a plurality of circular holes that are cooling apertures 85 around the interface perimeter between the outer and inner perimeter of the power rings. These holes are used to cool the power rings through enabling air to more effectively circulated around the slip ring assembly.

[0095] With reference to Figures 7 & 8, power rings 10, 20, 30 are spaced apart, with the spacing between power ring 20 and power ring 30 about 80 mm which is greater than the spacing between power ring 30 and the ground ring segments 40, 50, which is about 50 mm. The external diameter of the power and slip rings are about 270 mm. The internal diameter of the hub is about 110 mm. As illustrated in Figure 8, the threaded pins have a shorter length (=25 mm) than the thickness of the outer perimeter of the ground ring 55 (=30 mm). The length of the fastening pin may be reduced through a combination of using a counter-sunk aperture 48 and the mounting plate 60 not extending to the outer perimeter, thereby enabling the ground ring to have a reduced thickness at a portion ofthe ground ring distal from the outer perimeter of the ground ring. However, for ease of access to the fastening pin, the fastening pin is preferably closer the outer perimeter of the ground ring 40 than the inner perimeter of the ground ring 50. Additionally, the complementary profile of the ground ring and mounting plate interface surfaces 53 is preferably configured such that the portion of the fastening pin embedded into the mounting plate is approximately equal to the portion of the fastening pin embedded into the ground ring segment 40, 50. This may be achieved through the thickness B of the ground ring segment 40, 50 where the fastening pin engages with the mounting plate 60 is approximately 50% of the total thickness at the peripheral surface of the ground ring A.

[0096] For embodiments, in which one of more of the power rings are replaceable, the fastening pins would be preferably less than the thickness of the outer perimeter of the power ring (e.g. (=50 mm), with the fastening pins being about 40 mm in length. The power ring segments would include “cut-out” sections to enable the power ring segments to be removed from the hub without the need to disassemble any of the connecting rods 82, 84, 86. To enable more easy removal of the power ring segments from the hub and the connecting rods, in one embodiment, the separable power rings compose three or more segments, which are preferably of equal size.

[0097] The gap or spacing 47 between the ground ring 40, 50 and the power ring 30 is preferably at least about twice the length of the fastening pin 70, which enables sufficient space for a head 92 of an engagement tool 90 (outline of two engagement tools with different handles shown in Figure 8) to be manoeuvred into the gap 47. The handle 94 of the engagement tool preferably connects to the head 92 at approximately right angles to the axis of the fastening pin 70, such that the handle is not constrained by the limited spacing within the slip ring assembly. The gap 47 is about 50 mm, whilst the length of the fastening pin is about 25 mm, therefore the fastening pin represents about 50% of the gap. In a further embodiment, the handle 94” may extend at right angles directly from the head 92 to minimise the footprint of the fastening pin connecting device within the gap 47.

[0098] In another embodiment, the engagement head may be connected to a handle 94’ which extends through an aligned cooling aperture 85 in the power ring 30. The handle may then angle away form the slip ring assembly (e.g. at right angles). By aligning the cooling apertures 85 on a neighbouring power ring 30 to the fastening pin apertures 72, the engagement tool is able to assert a greater levered force to remove the ground ring. In some embodiments the engagement head may be separable from the hand portion to enable the engagement head to be attached after the handle has been inserted throughthe cooling aperture, thereby enabling the engagement head diameter to be of greater diameter than the cooling hole.

[0099] With reference to Figures 9A to 9D, there is illustrated the mounting plate, which is typically integrally shrink-fitted to the hub cylinder which encompasses the shaft (not shown). The mounting plate comprises an inner perimeter surface 64, one outer perimeter surface 67 and an interface surface in between comprising surface engagement features provided by radial convex ridge 63, an inner annular planar interface surface 66 and an outer annular planar interface surface 68 of the mounting plate.

[0100] In some embodiments, the apertures in the ring and mounting plate for receiving the fastening pin are not located within the tongue and groove profile used to assist in aligning ring and the mounting plate together. As indicated in Figure 9A and 9C, the mounting plate surface not connecting to the ground ring is generally planar 65 with 6 apertures for receiving the fastening pins. The 6 apertures are disposed on an outer annular planar interface surface 68 of the mounting plate, which is wider than the inner annular planar interface surface 66, which extends between the radial convex ridge 63 and the inner perimeter surface 64 of the mounting plate.

[0101] The fastening pins do not generally extend through the mounting plate and therefore, in some embodiments, this side of the mounting plate may not comprise any apertures of the fastening pins. However, in some embodiments, when the gap between the housing and the ground ring permits, the fastening pins may be attached and removed from the housing side. In such embodiments, the apertures may be countersunk into the surface. As illustrated in Figures 9B and 9D, the interface side of the mounting plate comprises the radial convex ridge 63 which is tapered. The ridge is symmetrical and tapers as it narrows from the base to the extremity of the ridge.

[0102] The profile of the interface side of the mounting plate is complementary to that of the ground ring components in Figures 10A-C, as indicated in Figure 8. The ground ring components 40, 50 comprise an inner perimeter surface 52, an outer perimeter surface 53, which is in operable engagement with the carbon brushes. The interface surface of the ground ring comprising a radial tapered concave groove 51 which inter-lockingly connects with the radial convex ridge 63. The opposing side to the interface surface comprises three counter sunk apertures 42 for receiving fastening pins. The inner side 59 of the outer perimeter surface 53 of the ground ring components operably engages with the outer perimeter surface 67 of the mounting plate.

Claims

CLAIMSWhat is claimed is:

1. A wind turbine comprising: a generator comprising a shaft; and a slip ring assembly mounted on the shaft adjacent a housing, wherein the slip ring assembly is mounted on the shaft and comprises at least one power ring or ground ring, said ground ring disposed at an end of the slip ring assembly adjacent the housing, the ground ring and power ring each comprise an outer perimeter, an inner perimeter, and at least one interface surface between the outer perimeter and the inner perimeters, wherein the at least one power ring or ground ring comprises least two separatable components each which enable the at least one ground ring or power ring to be separately replaceable from around the shaft, and wherein the at least one power ring or ground ring is mounted on the shaft with a plurality of fastening pins, said fastening pins comprising a length less than a gap between the at least one ground ring or power ring and (i) a nearest power ring or ground ring; or (ii) the housing.

2. The wind turbine of claim 1 , wherein the slip ring assembly comprises a power ring sub-assembly comprising at least one power ring connected to a hub, said hub is mounted on the shaft.

3. The wind turbine of claim 2, wherein the slip ring assembly further comprises a ground ring, said ground ring is connected to a mounting plate, said mounting plate is connected to one or both of the shaft and the power ring sub-assembly.

4. The wind turbine according to any one of the preceding claims, wherein the fastening pins have a length that is less than 70% of the gap between power or ground ring and the nearest power or ground ring, from which the fastening pins are extracted towards.

5. The wind turbine according to any one of the preceding claims, wherein the length of the fastening pins is less than 70% of the gap between ground ring and the housing from which the fastening pins are extracted towards.

6. The wind generator of any one of the preceding claims, wherein the fastening pins are extractable and attachable to the ground ring from a power ring side of the ground ring.

7. The wind generator of claim 6, wherein the gap between the ground ring and the nearest power ring is greater than the gap between the ground ring and the housing.

8. The wind generator of claim 6 or 7, wherein the gap between the ground ring and the nearest power ring is at least 20% greater than the gap between the ground ring and the housing.

9. The wind generator of claim 1 , wherein the fastening pins are extractable and attachable to the ground ring from a housing side of the ground ring.

10. The wind turbine of any one of the preceding claims, wherein the fastening pins comprise a length less than the an outer perimeter thickness of the corresponding power or ground ring.

11. The wind turbine according to any one of the preceding claims, wherein the fastening pins, when attached, are embedded between 35% and 65% of their length into a hub.

12. The wind turbine according to any one of the preceding claims, wherein the fastening pins are evenly distributed radially around the power or ground ring.

13. The wind turbine according to any one of the preceding claims, the ground ring comprises a plurality of apertures for receiving the fastening pins, wherein the plurality of apertures is aligned with a plurality of cooling apertures of the nearest power ring.

14. The wind turbine according to claim 13, wherein the cooling apertures comprise a greater diameter that the plurality of apertures in the ground ring.

15. The wind turbine according to any one of the preceding claims, wherein the slip ring assembly further comprises at least one mounting plate radially extending from the hub, said mounting plate comprising an attachment point from which to attach the power or ground ring.

16. The wind turbine according to claim 15, wherein the mounting plate further comprises an interface surface from which to align to the interface surface of the power or ground ring.

17. The wind turbine according to claim 16, wherein the interface surface of the mounting plate comprises a convex or concave surface feature on the mounting plate and an opposing surface feature on the power or ground ring, such the surface features mate together to form a concave-convex alignment interface.

18. The wind turbine according to any one of the preceding claims, wherein one or more of the separatable components of the power or ground ring; the interface surface of ring and an interface surface of the mounting plate are coated with a conductive paste.

19. The wind turbine according to any one of claims 1 to 18, wherein the power or ground ring comprises an interface surface comprising a concave surface feature.

20. The wind turbine according to claim 19, wherein the concave surface feature tapers from an outer perimeter of the concave feature to a terminus of the concave feature, with a diameter of the outer perimeter being greater than the diameter of the terminus.

21. The wind turbine according to any one of claims 19 or 20, wherein the concave surface feature is disposed between a planar surface proximal the hub and a planar surface distal the hub.

22. The wind turbine according to claim 21 , wherein the planar surfaces are substantially parallel to the interface surface of the power or ground ring.

23. The wind turbine according to claim 21 or 22, wherein the attachment point comprises a plurality of apertures on the distal planar surface of the power or ground ring for alignment to corresponding apertures on the mounting plate.

24. The wind turbine according to any one of claims 1 to 18, wherein the interface surface of the power or ground ring facing a mounting plate comprises a first planar surface extending at right angles from the outer perimeter towards the inner perimeter; asecond planar surface extending from the first planar surface towards the mounting plate; a third planar surface extending from the second planar surface in a parallel direction to the first planar surface with a distance between the third planar surface and an opposing surface representing between 35% and 65% of the thickness of the outer perimeter of the ring; said third planar surface comprising an aperture for a fastening pin; a concave or convex surface feature; and a fourth planar surface extending from the concave or convex segment parallel to the third planar surface.

25. The wind turbine according to claim 24, wherein the fourth planar surface extends to the inner perimeter of the ring.

26. The wind turbine according to claim 24 or 25, wherein the third planar surface is longer than the fourth planar surface.Tl. The wind turbine according to any one of the preceding claims, wherein the power or ground ring further comprise at least one jacking hole extending through the power or ground ring and aligned to an interface surface of the mounting plate.

28. A replacement kit for a replacement of a ground ring or power ring from the slip ring assembly of the wind turbine according to any one of the preceding claims, comprising: at least two separable replacement components which enable one or both of the ground ring and power ring to be separately replaced from around the generator shaft; a fastening pin connecting device comprising: a head portion comprising a surface engagement tool for locking engagement with a surface fixture of the fastening pin; and a handle portion for at least performing a moving action to unfasten the fastening pin from the ground ring or power ring, wherein the surface engagement tool is able to fit: in the gap between the power or ground ring and the nearest power ring; in the gap between the ground ring and the housing; or through the gap between a cooling hole of an adjacent power ring, to engage and remove or reattach the fastening pin from the power or ground ring.

29. A method of replacing a power or ground ring from a slip ring assembly within a wind turbine according to any one of claims 1 to 27 comprising:engaging the surface engagement tool of claim 28 with a surface engagement feature of the fastening pin; moving the surface engagement tool to facilitate the release of the fastening pin from the power or ground ring; repeating said procedure on each of the remaining fastening pins to all of the fastening pins have been removed; removing each of the components of the power or ground ring; replacing each of the components of the power or ground rings with new or refurbished power or ground ring; and using the surface engagement tool attaching the replaced components with a plurality of fastening pins, wherein the surface engagement tool is able to fit (i) in the gap between the power or ground ring and the nearest power ring; (ii) in the gap between the ground ring and the generator housing; or (iii) through the gap between a cooling hole of an adjacent power ring to engage and remove and / or re-attach the fastening pin from the power or ground ring.

30. The method according claim 29, wherein a surface engagement tool is interfaced with a jacking pin placed into a jacking hole of the power or ground ring, such a motion of the jacking pin against the mounting plate separates the power or ground ring from the mounting plate when unfastened.

31. A slip ring assembly as defined in any one of claims 1 to 27.

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