Nacelle assembly for a wind turbine

Abstract

In a first aspect, a nacelle assembly for a wind turbine is provided. The nacelle assembly is connected to a wind turbine tower by a yaw system and includes a forward region coupled to a rotor including a rotor hub and at least one rotor blade. The nacelle assembly further includes a nacelle having a cover structure housing wind turbine components and an additional wind flow deflector system coupled to an outer side of the cover structure to direct wind flowing toward the nacelle for reducing drag of the nacelle when a wind direction is misaligned relative to a longitudinal wind direction in a yaw system failure event.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to nacelle assemblies for wind turbines having a nacelle and a wind flow deflector system, and wind turbines comprising such nacelle assemblies. BACKGROUND

[0002] Modern wind turbines are typically used to supply electricity into an electrical grid. Such wind turbines generally comprise a tower and a rotor arranged on the tower. The rotor, which typically comprises a hub and a plurality of blades, is rotated under the influence of the wind on the blades. The rotation generates a torque, which is normally transmitted to a generator either directly ("direct drive") through a rotor shaft or by using a gearbox. In this way, the generator generates electricity that can be supplied to the electrical grid.

[0003] Most wind turbines comprise a yaw system for orienting the rotor of the wind turbine along the prevailing wind direction. Typically, the yaw system holds the position by brakes (e.g. hydraulic brake calipers and / or electric brakes of a yaw motor) when the rotor is aligned with the wind direction. When the rotor is not aligned with the wind direction, the yaw system rotates the nacelle into the proper alignment with the wind. Thus, the nacelle can be rotated about the longitudinal axis of the tower into and out of the wind direction. The rotatable connection between the wind turbine tower and the nacelle is called a yaw bearing.

[0004] The nacelle can house the generator and / or the converter and several electrical components that control the operation of the generator. For example, in direct drive wind turbines, the generator can be positioned within or form part of the nacelle. In examples of wind turbines with a gearbox, the nacelle can house the generator and the drive train comprises a gearbox.

[0005] The length of the wind turbine blades and the height of the wind turbine are constantly increasing, with the aim of extracting as much kinetic energy from the wind as possible and thereby generating more electrical energy. This can therefore require increasing the size of the wind turbine components within the nacelle, such as the generator, the converter, the transformer or the gearbox. A larger nacelle can therefore be required to accommodate these larger wind turbine components. The nacelle is typically transported from the manufacturing facility to the installation site by truck, rail or ship for lifting on top of the wind turbine tower. Depending on the shape and size of the nacelle, it can be difficult to transport the nacelle from the manufacturing plant to the wind turbine park.

[0006] Larger nacelles can also increase the nacelle's area facing the wind. In some events, for example in high wind speeds or storm events, power cannot be supplied to the yaw system and thus the nacelle cannot be aligned with respect to the prevailing wind direction. During these events, the wind direction can vary, causing the nacelle to be misaligned with respect to the prevailing wind direction. When the nacelle is misaligned, the sides of the nacelle can experience wind flow. The sides can thus provide a resistance or aerodynamic drag with respect to the wind flow. The wind flow acting on the sides of the nacelle can induce high bending loads on the wind turbine tower, in particular in high wind turbine towers. The tower and the tower's connection to the foundation can have to be designed to withstand a misaligned nacelle experiencing high wind speeds. Otherwise, the maximum wind speed that can be withstood by the wind turbine can have to be reduced.

[0007] Essentially oval nacelles can be used to reduce the aerodynamic drag or resistance coefficient of the nacelle. This oval shape can reduce the loads on the wind turbine. However, due to this particular shape, these types of nacelles are generally difficult to manufacture and transport, and the circular or oval shape does not allow an efficient use of the space inside the nacelle that houses different components.

[0008] The present disclosure provides examples of systems and methods that at least partially address some of the above-mentioned drawbacks. SUMMARY

[0009] In an aspect, a nacelle assembly for a wind turbine is provided. The nacelle assembly is connected to a wind turbine tower by a yaw system and has a front region coupled to a rotor comprising a rotor hub and providing at least one rotor blade. The nacelle assembly comprises a nacelle having a cover structure to house wind turbine components. The cover structure comprises a front side arranged at the front region, a rear side opposite the front side, a first side and a second side, and a top side and a bottom side. The cover structure extends along a longitudinal axis from the front side to the rear side. The nacelle assembly further comprises an additional wind flow deflector system coupled to the outer sides of the cover structure to direct wind flowing towards the nacelle for reducing the resistance of the nacelle when the wind direction is misaligned with respect to the longitudinal axis in a yaw system failure event.

[0010] In this disclosure, a yaw system failure event refers to an event during the operation of the wind turbine in which the yaw system is unable to rotate the nacelle. This can occur when one or more yaw drives are damaged such that there is not enough torque provided to rotate the nacelle. The yaw system failure event can include a yaw system power failure event in which there is no power or not enough power supplied to the yaw system to rotate the nacelle to follow the prevailing wind direction.

[0011] A yaw system power failure event can be caused by a grid loss event or a backup power insufficient to rotate the nacelle or a yaw drive damage. During some grid loss events, the blades cannot be feathered such that the load cannot be reduced by feathering the blades. A grid loss event can be caused by an extreme storm, such as a hurricane or typhoon. During an extreme storm, high winds and grid loss can occur simultaneously.

[0012] In this disclosure, the additional wind deflector system refers to an aerodynamic profile that can be coupled to the nacelle to change the aerodynamics of the nacelle.

[0013] In this disclosure, the misalignment of the nacelle or a longitudinal axis of the nacelle with respect to the wind direction refers to a direction of the wind speed that is not substantially parallel to the longitudinal axis of the nacelle. For example, the nacelle can be misaligned with respect to the wind direction when an angle between the wind direction and the longitudinal axis of the nacelle is greater than 10°, in particular greater than 20°, and more particularly greater than 30°.

[0014] When the wind direction is misaligned with respect to the longitudinal axis of the nacelle, the additional wind deflector system can change the aerodynamic profile of the nacelle to reduce the drag of the nacelle. The aerodynamic resistance of the nacelle can thus be reduced. The load acting on the wind turbine for a given wind speed when the nacelle is misaligned can thus be reduced when compared to a nacelle without the additional wind deflector system. The tower or the connection of the tower to the foundation can thus be optimally or more optimally used. In addition, an expensive backup power system to provide power to the yaw system during a grid loss event can be avoided. The cost of the wind turbine can thus be reduced without adversely affecting the structural integrity of the wind turbine.

[0015] After the nacelle is transported to the installation site, the additional wind deflector system can be coupled to the outside of the cover structure. The additional wind deflector system thus does not adversely affect the shape and size of the nacelle during transportation. In addition, because the additional wind deflector system is coupled to the outside of the cover structure, the space inside the nacelle for accommodating wind turbine components can be kept as small as possible to accommodate the components without increasing the overall size of the nacelle. A compact nacelle that accommodates wind turbine components, such as electrical converters or generators, can thus be provided.

[0016] Technical solution 1. A nacelle assembly for a wind turbine, the nacelle assembly being connected to a wind turbine tower by a yaw system and having a front region coupled to a rotor, the rotor comprising a rotor hub and at least one rotor blade, the nacelle assembly comprising:

[0017] a nacelle having a cover structure accommodating wind turbine components, the cover structure comprising a front side arranged at the front region, a rear side opposite the front side, a first side and a second side, and a top side and a bottom side;

[0018] the cover structure extends along a longitudinal axis from the front side to the rear side; and

[0019] the nacelle assembly further comprises:

[0020] an additional wind flow deflector system coupled to an outer side of the cover structure to direct wind flow toward the nacelle for reducing drag of the nacelle when wind flow is misaligned relative to the longitudinal axis in a yaw system failure event.

[0021] Technical solution 2. The nacelle assembly of technical solution 1, wherein the yaw system failure event comprises a grid loss event.

[0022] Technical solution 3. The nacelle assembly of any one of technical solutions 1-2, wherein the additional wind flow deflector system comprises a plurality of wind flow deflector devices.

[0023] Technical solution 4. The nacelle assembly of technical solution 3, wherein one or more wind flow deflector devices cover a portion of a first top edge region formed between the top side and the first side portion and / or a portion of a second top edge region formed between the top side and the second side portion.

[0024] Technical solution 5. The nacelle assembly of any one of technical solutions 3-4, wherein one or more wind flow deflector devices cover a portion of the first side portion and / or the second side portion.

[0025] Technical solution 6. The nacelle assembly of any one of technical solutions 3-5, wherein one or more wind flow deflector devices comprise a plate extending from a proximal end connected to the cover structure to a free distal end.

[0026] Technical solution 7. The nacelle assembly of technical solution 6, wherein the proximal end is connected to one of the first side portion and the second side portion forming an acute angle between the plate and the side portion.

[0027] Technical solution 8. The nacelle assembly of technical solution 6, wherein the proximal end is connected to the cover structure at a top edge region formed between the top side and one of the first side portion and the second side portion forming an acute angle between the plate and the side portion.

[0028] Technical solution 9. The nacelle assembly of any one of technical solutions 6-8, wherein the plate is hingedly connected to the cover structure.

[0029] Technical solution 10. The nacelle assembly of any one of technical solutions 6-9, wherein the plate is curved.

[0030] Technical solution 11. The nacelle assembly according to technical solution 10, wherein the free distal end of the plate faces the cover structure.

[0031] Technical solution 12. The nacelle assembly according to any one of technical solutions 3-11, wherein the one or more wind flow deflector devices comprise a reinforcement structure, in particular a strut connected to the cover structure.

[0032] Technical solution 13. The nacelle assembly according to any one of technical solutions 1-12, wherein the additional wind flow deflector system is configured to move from a rest position to a deployed position.

[0033] Technical solution 14. A wind turbine, comprising:

[0034] a tower;

[0035] a nacelle assembly according to any one of technical solutions 1-13 mounted on the tower;

[0036] a yaw system rotatably connecting the nacelle assembly to the tower; and

[0037] a rotor comprising a rotor hub and at least one rotor blade, the rotor being arranged at a front region of the nacelle assembly.

[0038] Technical solution 15. A method for reducing loads in a wind turbine comprising a nacelle assembly during a yaw system failure event, the method comprising:

[0039] detecting a yaw system failure event;

[0040] when detecting a yaw system failure event, triggering one or more wind flow deflector devices coupled to an outer side of a cover structure of the nacelle assembly to move the wind flow deflector devices to a deployed position. BRIEF DESCRIPTION OF DRAWINGS

[0041] Non-limiting examples of the present disclosure will hereinafter be described in conjunction with the appended drawings, in which:

[0042] Figure 1 a perspective view of a wind turbine according to one example of the present disclosure is shown;

[0043] Figure 2 a simplified internal view of a nacelle of a wind turbine according to one example of the present disclosure is shown;

[0044] Figure 3 an isometric view of a nacelle of a wind turbine according to one example of the present disclosure is shown schematically;

[0045] Figure 4 and Figure 5 Front views of a prior art cabin and a cabin assembly according to an example of the present invention, showing airflow from the side of the cabin's canopy structure;

[0046] Figure 6 An example of a cabin component is schematically shown as an example of this disclosure;

[0047] Figure 7 An example of a cabin component is schematically shown as an example of this disclosure;

[0048] Figures 8-11 Several examples of airflow deflector devices according to this disclosure are shown;

[0049] Figure 12 A flowchart illustrating an example of a method for reducing load during a yaw system failure event in a wind turbine, according to an example of this disclosure;

[0050] Figure 13 A flowchart illustrating an example of a method for reducing load during grid loss events in a wind turbine, according to an example of this disclosure. Detailed Implementation

[0051] In these figures, the same reference symbols are used to denote matching elements.

[0052] Figure 1 A perspective view of an example wind turbine 1 is shown. As shown, the wind turbine 1 includes a tower 2 extending from a support surface 3, a nacelle 4 mounted on the tower 2, and a rotor 5 coupled to the nacelle 4 in a front region. The rotor 5 includes a rotatable hub 6 and at least one rotor blade 7 coupled to and extending outward from the hub 6. For example, in the example shown, the rotor 5 includes three rotor blades 7. However, in alternative embodiments, the rotor 5 may include more or fewer than three rotor blades 7. Each rotor blade 7 may be spaced from the hub 6 to allow rotation of the rotor 5 to convert kinetic energy from wind into usable mechanical energy, and subsequently into electrical energy. For example, the hub 6 may be rotatably coupled to a generator 10 located within or forming part of the nacelle 4. Figure 2 This allows for the generation of electrical energy. The rotation of the rotor can be transmitted directly to the generator (e.g., in a direct-drive wind turbine) or transmitted to the generator via a gearbox.

[0053] Figure 2 Show Figure 1A simplified internal view of an example of the nacelle 4 of a wind turbine 1. As shown, a generator 10 may be disposed within the nacelle 4. Generally, the generator 10 may be coupled to the rotor 5 of the wind turbine 1 to generate electrical power from the rotational energy generated by the rotor 5. For example, the rotor 5 may include a main rotor shaft 8 coupled to a hub 6 for rotation therewith. The generator 10 may then be coupled to the rotor shaft 8 such that rotation of the rotor shaft 8 drives the generator 10. For example, in the illustrated embodiment, the generator 10 includes a generator shaft 11 rotatably coupled to the rotor shaft 8 via a gearbox 9. In an alternative example, the hub may be directly coupled to the rotor of the generator, and rotation of the hub may therefore drive the rotor of the generator.

[0054] Generator 10 can be electrically connected to the converter. The wind turbine converter allows the generator's output power to be adapted to the grid's requirements.

[0055] It should be understood that the rotor shaft 8, gearbox 9 and generator 10 are generally supported in the nacelle 4 by the base plate or support frame 12 positioned on top of the wind turbine tower 2.

[0056] The nacelle 4 is rotatably connected to the tower 2 via a yaw system 20. The yaw system includes a yaw bearing ( Figure 2 (Not visible in the image), the yaw bearing has two bearing members configured to rotate relative to the other. The tower 2 is coupled to one of the bearing members, and the floor plate or support frame 12 of the nacelle 4 is coupled to the other bearing member. The yaw system 20 includes a ring gear 21 and multiple yaw actuators 22, each having a motor 23, a gearbox 24, and a pinion 25 for meshing with the ring gear to rotate one of the bearing members relative to the other. The motor 23 can be electrically connected to the power grid.

[0057] The nacelle 4 also includes a cover structure 50 for housing wind turbine components. In this example, the wind turbine components housed in or surrounded by the cover structure 50 include a generator 10, a converter, a gearbox 9, and a shaft 8. In other examples, the wind turbine components arranged within the nacelle may refer to the converter and the generator.

[0058] Figure 3 A nacelle according to an example of this disclosure is schematically shown. The nacelle 4 includes a forward region 13, at which a rotor 5 is coupled, the rotor 5 including a hub 6 and at least one rotor blade 7. The nacelle 4 includes a cover structure 50 comprising a front side 51 disposed at the forward region 13 and a rear side 52 opposite to the front side 51. The nacelle also includes a first side portion 61 and a second side portion 62 extending from the front side 51 to the rear side 52 in a direction parallel to a longitudinal axis 31, wherein the first longitudinal side 61 and the second longitudinal side 62 are disposed on opposite sides of the cover structure.

[0059] The cover structure 50 further comprises a top side 70 extending from the front side 51 to the rear side 52 in a direction parallel to the longitudinal axis 31 and from the first side portion 61 to the second side portion 62 in a direction parallel to the transverse axis 32, wherein the transverse axis 32 is perpendicular to the longitudinal axis 31. Further, the cover structure of the figure comprises a bottom side 80 extending from the front side 51 to the rear side 52 in a direction parallel to the longitudinal axis 31 and from the first side portion 61 to the second side portion 62 in a direction parallel to the transverse axis 32. The top side 70 and the bottom side 80 are arranged on opposite sides of the cover structure.

[0060] The first side portion 61 and the second side portion 62 can extend from the bottom side 80 to the top side 70 in a direction parallel to the yaw axis 33, wherein the yaw axis 33 is perpendicular to the longitudinal axis 32 and the transverse axis 32.

[0061] The cover structure 50 of the figure further comprises a first top edge 71 and a second top edge 72 formed between the top side 70 and the first side portion 61 and the second side portion 62, respectively. In addition, the cover structure can comprise a first bottom edge 81 and a second bottom edge 82 formed between the bottom side 80 and the first side portion 61 and the second side portion 62, respectively (not shown in the figure). Figure 3

[0062] An additional wind flow deflector system according to any of the examples described herein can be permanently coupled to the outer side of the cover structure to form a nacelle assembly. For example, the additional wind flow deflector system can at least partially cover or shield a portion of the first side portion and the second side portion. Thus, in a yaw system failure event, when the longitudinal axis of the nacelle is misaligned with respect to the wind direction, the additional wind flow deflector system can change the external shape of the nacelle on the side portions to reduce the drag of the nacelle. In some examples, the yaw system failure event can comprise a grid loss event. In some examples, the yaw system failure event can comprise a failure of the yaw system. Thus, the nacelle cannot be rotated by the yaw system and the nacelle cannot follow changes in the wind direction.

[0063] When the nacelle is misaligned with respect to the wind direction, the wind flows towards one of the first side portion and the second side portion.

[0064] In this disclosure, the misalignment of the nacelle refers to the longitudinal axis of the nacelle not substantially corresponding to the prevailing wind direction. For example, the prevailing wind direction can have changed, for example due to a failure of the yaw system, but the nacelle can not be rotated around the yaw axis to align with the wind direction.

[0065] The drag coefficient (typically denoted as c d ) is a dimensionless quantity that quantifies the resistance or drag of an object (such as a nacelle) in a fluid environment, such as air or wind. A low drag coefficient indicates that the object has better aerodynamics, for example, providing less resistance to the wind flowing around the object. The drag coefficient is generally defined as:​

[0066]

[0067] wherein:

[0068] c d is a drag coefficient;

[0069] F d is a drag force, which is the force component of the wind direction;

[0070] p is the mass density of the wind;

[0071] w is the wind speed relative to the object;

[0072] A is a reference area of the nacelle.

[0073] The drag force (F d ) is proportional to the drag coefficient (c d ). In this disclosure, the drag force and the drag are used indistinctly. Thus, when the drag coefficient is reduced, the drag is also reduced. The drag force acting on the nacelle generates a bending moment around the tower base. Reducing the drag force can thus reduce the load on the tower base. The drag force can be reduced by reducing the drag coefficient, and the drag coefficient depends on the shape of the object. Thus, the shape of the part of the nacelle facing the wind, e.g. the side, can be changed by the additional wind flow deflector system to reduce the drag coefficient of the nacelle, and thus the drag force.

[0074] In examples of the nacelle Figure 3 has a substantially cuboid or rectangular box shape. In some examples, the edges formed between the sides of the cover structure can be rounded. The cuboid shape can facilitate the transportation and storage of the nacelle. In some examples, the cover structure can have a standard container shape. Moreover, the cuboid shape can maximize the use of the internal space inside the nacelle to accommodate wind turbine components. After the nacelle is transported to the wind turbine site, the additional wind flow deflector system can be permanently coupled to the outside of the cover structure or deployed. Thus, the transportation of the nacelle is not adversely affected by the shape of the additional wind flow deflector system.

[0075] In some examples, the additional wind flow deflector system is movable from a rest position to a deployed position. The wind turbine can operate with one or more wind flow deflector devices of the additional wind flow deflector system in the rest position, i.e. the additional wind flow deflector system does not substantially change the aerodynamic profile of the nacelle. Upon detection of a yaw system failure event, the additional wind flow deflector system can be moved to the deployed position. The actuator can move one or more wind flow deflector devices of the additional wind flow deflector system from the rest position to the deployed position. In the deployed position, the additional wind flow deflector system reduces the drag of the nacelle when the wind direction is misaligned relative to the longitudinal axis of the nacelle.

[0076] Figure 4 and Figure 5 respectively show front views of a nacelle without and with an additional wind flow deflector system experiencing wind flow from the side of the cover structure of a wind turbine. A rotor 5 with a hub 6 and three blades 7 is rotatably coupled to a front region 13 of the nacelle 4. The nacelle 4 of the example in these figures comprises a cover structure 50 with a first side 61 and a second side 62. However, Figure 5 In the figure on the right, the additional wind flow deflector system 100 is coupled to the outside of the cover structure 50 to form a nacelle assembly 200.

[0077] In these figures, the wind flow is towards the first side 61. The wind direction is misaligned relative to the longitudinal axis of the nacelle. Figure 4 In the figure on the left (without the additional wind flow deflector system), the wind separates at the first top edge, causing the wind wake to widen. As the wake widens, the wind pressure on the second side 62 drops and the drag increases. As a result, the drag acting on the first side 61 also increases, and thus the load on the tower base.

[0078] However, Figure 5 In the figure on the right, the additional wind flow deflector system 100 coupled to the cover structure 50 with the wind flow directs the flow towards the nacelle. The additional wind flow deflector system can reduce the separation of the wind around the top and bottom sides of the cover structure. As a result, the wake on the second side 62 can be reduced or narrowed. When compared to the nacelle of Figure 4 The narrowed wake on the second side can cause the drag acting on the first side 61 to be reduced when compared to the nacelle of

[0079] Figure 5 The additional wind flow deflector system 100 of the nacelle assembly 200 comprises a plurality of wind flow deflector devices 110. In particular, the additional wind flow deflector system 100 comprises four wind flow deflector devices 110. In other examples, the additional wind flow deflector system can comprise two wind flow deflector devices. For example, one wind flow deflector device can extend along the first side, while the other wind flow deflector device can extend along the second side.

[0080] In some examples, one or more of the plurality of wind flow deflector devices can cover a portion of a first top edge portion formed between the top side and the first side portion and / or a portion of a second top edge region formed between the top side and the second side portion. Figure 5 In examples, each of the wind flow deflector devices covers or shields a portion of one of the edges formed between the top side and the side portions and between the bottom side and the side portions.

[0081] Alternatively or in addition, one or more of the plurality of wind flow deflector devices can cover or shield a portion of the first side portion and / or the second side portion. In Figure 5 In examples, the wind flow deflector devices cover a portion of the edges formed between the side portions and the top portion and the bottom portion, and further cover a portion of the first side portion and the second side portion. In some examples, some of the wind flow deflector devices can cover a portion of the edges, and some of the wind flow deflector devices can cover a portion of the side portions.

[0082] In some examples, one or more of the plurality of wind flow deflector devices can cover a portion of the top side. For example, one wind flow deflector device can extend from the first side portion to the second side portion. This one wind flow deflector device can be coupled to the top side of the cover structure. In further examples, another wind flow deflector device can cover and extend from the first side portion to the second side portion along a portion of the bottom side. This wind flow deflector device extending along a portion of the bottom side can be coupled to the bottom side.

[0083] In this figure, the wind flow deflector device comprises a plate extending from a proximal end connected to the cover structure to a free distal end. In this example, the plate is substantially flat, but in other examples the plate can be curved. The proximal end can be connected to a side portion or an edge, for example. For example, the proximal end of the wind flow deflector device can be connected to the first side portion or the second side portion, forming an acute angle between the side portion at which the plate is connected to the proximal end.

[0084] In further examples, the wind flow deflector device can be an elongated body extending along the side portion from the front side to the back side. The elongated body can have a cross-sectional triangular shape or a cross-sectional semi-elliptical shape.

[0085] In yet further examples, the wind flow deflector system can comprise a wind flow deflector device having a body and another wind flow deflector device comprising a plate.

[0086] Figure 6 An example of a nacelle assembly according to one example of the disclosure is schematically illustrated. The nacelle assembly 200 has a front region where a wind turbine rotor is coupled, and comprises a nacelle 4 and an additional wind flow deflector system 100.

[0087] Figure 6The nacelle has a cover structure to accommodate a wind turbine component, such as an electrical converter or a gear box or a generator. The cover structure has a substantially cuboid shape and comprises a front side 51 arranged in a front region and a rear side (not shown in this figure) opposite the front side. The cover structure further comprises a first side 61 and a second side 62 extending from the front side 51 to the rear side in a direction parallel to the longitudinal axis, wherein the first and second sides are arranged on opposite sides of the cover structure. In addition, Figure 6 The cover structure comprises a top side 70 and a bottom side 80 extending from the front side 51 to the rear side in a direction parallel to the longitudinal axis and from the first side 61 to the second side 62 in a direction parallel to the transversal axis, wherein the transversal axis is perpendicular to the longitudinal axis.

[0088] Figure 6 In the shown embodiment, the cover structure further comprises a first top edge 71 and a second top edge 72 formed between the top side 70 and the first and second sides 61, 62, respectively, and a first bottom edge 81 and a second bottom edge 82 formed between the bottom side 80 and the first and second sides 61, 62, respectively.

[0089] The additional wind flow deflector system 100 of this figure comprises a wind flow deflector arrangement extending along the longitudinal axis (perpendicular to the paper). In this example, the wind flow deflector arrangement is coupled to the outer side of the cover structure to at least partially cover a portion of the first and second sides 61, 62. Thus, when one of the sides is subjected to a wind flow, the resistance can be reduced.

[0090] Figure 6 In the shown embodiment, the wind flow deflector arrangement comprises a plate extending from a proximal end 111 coupled to the cover structure to a free distal end 112 (indicated only in the wind flow deflector arrangement associated with the second side 62 for the sake of clarity).

[0091] The additional wind flow deflector system 100 of this figure comprises a first top wind flow deflector arrangement 171 having a proximal end 111 coupled to the first top edge portion 71, a second top wind flow deflector arrangement 172 having a proximal end 111 coupled to the second top edge 72, a first bottom wind flow deflector arrangement 181 having a proximal end 111 coupled to the first bottom edge 81, and a second bottom wind flow deflector arrangement 182 having a proximal end 111 coupled to the second bottom edge 82.

[0092] Figure 6 In the shown embodiment, the wind flow deflector arrangements 171 and 181 are at an acute angle to the first side 61 and the wind flow deflector arrangements 172 and 182 are at an acute angle to the second side 62.

[0093] In this figure, the wind flow deflector devices are curved. Thus, the reduction in drag can be increased. The curved wind flow deflector devices can also allow an increased range of upward flow angles, i.e. the angle of attack of the wind from the underside, so that the amount of drag can be additionally reduced for some wind directions when compared to a nacelle without the additional wind flow deflector system. In this example, the free distal ends 112 of the wind flow deflector devices covering one side face each other, and the proximal ends are tangential to a portion of the edge.

[0094] In other examples, the nacelle assembly can include wind flow deflector devices coupled to the first side and the side portions by the proximal ends of the plates. In some examples, the plates can form an acute angle between the plate and the side portion to which the proximal end is coupled.

[0095] In further examples, the proximal end of one wind flow deflector device can be coupled to the top side or the bottom side.

[0096] Similar to the nacelle assembly depicted in Figure 6 depicted in Figure 7 Another example of a nacelle assembly according to one example of the present disclosure is schematically illustrated. However, Figure 7 In this figure, the free distal ends 112 of the wind flow deflector devices face the side portions. The free distal ends 112 of the wind flow deflector devices 172 and 182 face the second side portion 62, and the free distal end 112 of the wind flow deflector device 171 faces the first side portion 61. The wind flow deflector devices extend outwardly from the proximal end and inwardly at the free distal end, so that the free distal end points or faces the side portion.

[0097] Figures 8-11 Several examples of wind flow deflector devices according to the present disclosure are illustrated.

[0098] Figure 8 And Figure 9 The wind flow deflector device 110 of comprises a plate 113 and a support structure 120 connecting the plate to the cover structure. Figure 8 In this figure, the plate 113 is curved and substantially covers the edge formed between the top side and the side portion and the bottom side and the side portion. Figure 9 The plate 113 of is generally flat and shields a portion of the side portion. The plate 113 arranged on the first side portion can direct wind flow to the top side and the bottom side more upstream of the first side portion of the cover structure. The plate 113 arranged on the second side portion can capture the wake vortex. In these figures, the support structure 120 can be connected to the edge and / or the side portion. In other examples, the support structure can be coupled to the top side and the bottom side of the cover structure. The plates of these examples can direct wind flow from one side portion to the other side portion to provide a smoother transition from the side portions to the top side and the bottom side than a nacelle without the additional wind flow deflector system for reducing drag.

[0099] Figure 10 The wind flow deflector device 110 of is similar toFigure 6 The wind flow deflector device shown in FIG. 1 A. However, Figure 10 The wind flow deflector device of FIG. 1 A includes a reinforcement structure. The reinforcement structure can maintain a predetermined shape of the wind flow deflector device subjected to high wind speeds. Thus, the reinforcement structure can prevent excessive deflection of the wind deflector device. Figure 10 In some examples, the length of the strut can be variable to change the aerodynamic shape of the wind deflector device, e.g., the strut can be a telescoping pole. Additionally or alternatively, the reinforcement structure can include a rib extending from the proximal end 111 to the free distal end 112.

[0100] Other examples of wind flow deflector devices according to the present disclosure can also include a reinforcement structure.

[0101] Instead of a wind flow deflector device having a plate, Figure 11 The wind flow deflector device of FIG. 1 A includes a body having a guide surface 141 for guiding a wind flow and a coupling surface 142 connecting the body to a cover structure of a nacelle. In this example, the body has a substantially cross-sectional triangular shape, however, in other examples, the body can have a substantially cross-sectional semi-elliptical shape. In these examples, the guide surface can thus be curved. In some examples, the coupling surface can engage with a portion of the side. In some examples, the coupling surface can engage with a portion of the top side or the bottom side or with a portion of the edge.

[0102] A wind flow deflector device according to any of the examples described herein can be made of a flexible material. The shape of the wind flow deflector device can thus be adapted to the pressure exerted by the wind on the wind flow deflector device. The material and the rigidity of the device can be chosen so that it deforms in a desired manner in case of an increase in wind pressure. In some examples, the wind flow deflector device can be made of aluminum, composite material or rubber. In some examples, the wind flow deflector device can be inflatable.

[0103] An additional wind flow deflector system according to any of the examples disclosed herein can be coupled to the outer side of the cover structure by gluing or fastening or a combination thereof. For example, the proximal end of the wind flow deflector device can be screwed to the cover structure. In further examples, the wind flow device can be coupled to the cover structure by magnetic force. In other examples, a body-shaped wind flow deflector device can include a coupling surface glued to a portion of the cover structure. Thus, the wind flow deflector device can be easily coupled to the cover structure at the installation site, e.g., before lifting the nacelle or even after connecting the nacelle to the tower.

[0104] In some examples, the wind flow deflector system can be hingedly connected to the cover structure. For example, the proximal end of the plate can be connected to a side or edge of the cover structure by a hinge. Thus, the angle of the plate relative to the side can be changed. The shape of the plate can be adapted to the expected wind speed at a particular site. Thus, the drag coefficient of the wind flow deflector device can be changed depending on the situation to reduce drag.

[0105] In some examples, the plate can be moved from a rest position to a deployed position. The plate can be in the rest position when it does not substantially change the aerodynamic resistance of the nacelle, for example when the plate is substantially parallel to the side. The plate can be in the rest position when the nacelle is not experiencing high speed winds, and thus the nacelle is aligned with the wind direction. The plate can be in the deployed position when it substantially changes the aerodynamic resistance of the nacelle, for example when the plate is substantially perpendicular to the side. Thus, the drag can be changed, i.e. deployed, when the wind speed experienced by the nacelle is higher than a predetermined value when misaligned. Thus, the aerodynamics of the nacelle can not be adversely affected when the wind turbine is operating normally.

[0106] In some examples, the plate can be passively moved from a rest position to a deployed position. In these examples, the wind applied to the wind flow deflector device can change its shape or cause the deployment to reduce the resistance offered to the wind. This can help to reduce the load acting on the wind turbine when the electrical supply to the nacelle interior members can be (temporarily) lost, for example in a grid loss event.

[0107] In some examples, the wind flow deflector device can comprise an actuator to move the plate from the rest position to the deployed position.

[0108] In some examples, the actuator can comprise an electromagnet to hold the plate in the rest position and allow the plate to move to the deployed position when the current is cut. Thus, the plate can be deployed when the electromagnet is not powered. The plate can thus be (automatically) deployed in a grid loss event.

[0109] In further examples, the actuator can comprise a telescopic rod extending from the rest position to the deployed position. Thus, the angle between the wind flow deflector device and the side can be controlled. Thus, the drag coefficient can be adjusted depending on, for example, the wind speed.

[0110] In some examples, the actuator can be powered by a power storage system. The power storage system can comprise a battery and / or a capacitor. Batteries store their potential energy in a chemical form, whereas the potential energy in a capacitor is stored in an electric field. The capacitor can be a supercapacitor. Supercapacitors can also be referred to as ultracapacitors or double layer capacitors. Supercapacitors differ from ordinary capacitors in that they have a much higher capacitance and energy density, while having a much higher power density.

[0111] In some examples, the power storage system that triggers the actuator for moving the wind flow deflector device can be a dedicated power storage system. In some examples, the actuator can use power stored in a power storage system used as a backup power source for other wind turbine components. For example, a backup power system used to temporarily provide power to a variable pitch system can be used to trigger the actuator. The backup power system can include a battery and / or a super capacitor used to provide power to the variable pitch system. The power required to trigger the actuator is lower than the power required to rotate the nacelle using a yaw system.

[0112] In this disclosure, the length of the nacelle and the length of the wind flow deflector device extend substantially parallel to the longitudinal axis of the nacelle. In some examples, the length of the one or more wind flow deflector devices can be substantially similar to the length of the nacelle, i.e. the one or more wind flow deflectors extend completely from the front side to the rear side of the cover structure. For example, for a nacelle having a length of 6 meters (236.22 inches), the length of the one or more wind flow deflector devices can be 6 meters (236.22 inches). In some examples, the length of the one or more wind flow deflector devices can be between 4 meters (157.48 inches) and 10 meters (393.70 inches).

[0113] In other examples, the length of the one or more wind flow deflector devices can be between 25% and 75% of the length of the cover structure. For example, the length of the one or more wind flow deflector devices can be between 1 meter (39.37 inches) and 7.5 meters (295.28 inches).

[0114] In some examples, several wind flow deflector devices can be arranged in a single row parallel to the longitudinal axis. For example, two wind flow deflectors can be arranged in a single row. The length of these two wind flow deflectors can for example be between 25% and 50% of the total length of the cover structure.

[0115] In those examples where several wind flow deflector devices are arranged in a single row parallel to the longitudinal axis, the wind flow deflector devices can be spaced apart or arranged continuously. For example, several wind flow deflector devices can be arranged adjacent to each other, i.e. one edge of one wind flow deflector device can contact one edge of an adjacent wind flow deflector device. Alternatively, a space can be arranged between two adjacent wind flow deflector devices.

[0116] In this disclosure, the height of the cover structure refers to the distance between the top side and the bottom side of the cover structure. The width of the wind flow deflector device is the distance between the proximal end and the free distal end. In some examples, the width of the one or more wind flow deflector devices can be between 15% and 70% of the height of the cover structure. For example, the width of the one or more wind flow deflector devices can be between 0.50 meters (19.68 inches) and 4 meters (157.48 inches).

[0117] In some examples, the width can be variable along the sides of the cover structure. For example, the width of the wind flow deflector device near the edges of the back side and / or the front side of the concave structure can be shorter than the width of the central portion of the wind flow deflector device. The wind flow deflector device can thus have a substantially circular shape with a longer width in the central portion and a shorter width in the portions proximate to the back side and the front side of the cover structure.

[0118] In another aspect, a wind turbine is provided, comprising a nacelle assembly according to any of the examples disclosed herein. The wind turbine comprises a tower having a nacelle mounted thereon, a yaw system rotatably connecting the nacelle assembly to the tower, and a rotor comprising a rotor hub and at least one rotor blade, the rotor being arranged at a front side of the nacelle assembly.

[0119] Figure 12 A flowchart illustrating an example of a method for reducing loads during a yaw system failure event according to the present disclosure is shown. The yaw system failure event can comprise a failure in one or several yaw drives and / or a grid loss. The wind turbine can comprise a nacelle assembly having an additional wind flow deflector system according to any of the examples described herein configured to move from a rest position to a deployed position.

[0120] At block 310, it is detected that a yaw system failure event. In those examples where the yaw system failure is a yaw drive failure, the yaw system failure event can be detected by a sensor coupled to the wind turbine controller. In those examples where the yaw system failure is a yaw system power failure event, i.e. an event where no power or not enough power is supplied to the yaw system to rotate the nacelle to follow the prevailing wind direction, the yaw system failure event can be detected directly as no power is supplied to the yaw system.

[0121] In some examples, the method can comprise obtaining a wind direction and / or a wind speed. Obtaining a wind speed can comprise determining a wind speed from at least one of a pitch angle, an electrical power output, a rotational speed of the rotor of the wind turbine. The wind turbine controller can use these operational parameters to determine the wind speed. Alternatively or additionally, the wind speed can be measured directly by a wind sensor or a differential pressure sensor arranged on the nacelle. In a grid loss event, these sensors can be self-powered and a backup power system can be used to provide power to the wind turbine controller to determine the wind speed.

[0122] Obtaining a wind direction can comprise determining a wind direction by obtaining a load from a blade sensor and using the wind turbine controller to determine the wind direction. In some examples, the wind direction can be measured directly by a wind sensor. In a grid loss event, the sensor can be self-powered and a backup power system can be used to provide power to the wind turbine controller.

[0123] For example, an anemometer can provide the wind direction and wind speed at the wind turbine.

[0124] At block 320, it is represented that one or more wind flow deflector devices coupled to the outboard side of the cover structure of the nacelle assembly are triggered by moving the wind flow deflector devices to a deployed position when the yaw system failure event is detected.

[0125] In some examples, moving the wind flow deflector devices to the deployed position can also take into account the wind speed and the wind direction. In this way, the wind flow deflector devices can be moved to the deployed position when a wind speed above a predetermined wind speed is determined and when the wind direction is misaligned relative to the longitudinal axis and when the yaw system failure event is determined. Thus, the wind flow deflector devices are not deployed when the nacelle is not misaligned or at a low wind speed.

[0126] Alternatively or additionally, the method can include determining a duration of the yaw system failure event. Moving the wind flow deflector devices to the deployed position can take into account the duration of the yaw system failure event. For example, the wind flow deflector devices can only be moved to the deployed position when the duration of the yaw system failure event is longer than a predetermined duration. According to this aspect, short yaw system failure events do not deploy the wind flow deflector devices. This can be the case in, for example, short grid loss events.

[0127] During the yaw system failure event, the wind direction can change and the nacelle can thus be misaligned. Because the nacelle cannot be rotated to follow the change in wind direction, the triggered wind flow deflector devices can reduce the drag of the nacelle to reduce the load acting on the wind turbine.

[0128] Figure 13 A flowchart showing an example of a method for reducing a load in a wind turbine during a grid loss event according to the present disclosure is shown. The wind turbine can include a nacelle assembly having one or more wind flow deflector devices according to any of the examples described herein configured to move from a rest position to a deployed position.

[0129] At block 410, a grid loss event is detected. The grid loss event can be detected directly in, for example, a transformer, converter, or generator because no power is supplied to the grid. A sensor from power can detect an increase in load and a wind turbine controller with an energy storage system can determine that there is a grid loss event.

[0130] At block 420, it is determined whether the nacelle is misaligned relative to the wind direction. In some examples, this can include obtaining the wind direction. Obtaining the wind direction can include determining the wind direction by obtaining a load from the blades with a sensor from power and determining the wind direction using a wind turbine controller with a backup power system. In some examples, the wind direction can be directly measured by a wind sensor.

[0131] At block 430, it is determined whether the wind speed is higher than a predetermined wind speed. The wind turbine controller can compare the wind speed to the predetermined wind speed. In some examples, determining whether the wind speed is higher than the predetermined wind speed can comprise obtaining the wind speed. In some examples, the wind direction can be measured directly by a wind sensor. The wind speed can be measured directly by a differential pressure sensor or a wind sensor arranged on the nacelle from the power. These sensors can be self-powered and a backup power system can be used to provide power to the wind turbine controller to determine whether the wind speed is higher than the predetermined wind speed.

[0132] At block 440, one or more wind flow deflector devices are triggered by moving the wind flow deflector devices from a rest position to a deployed position when the grid loss event is detected, the wind speed is higher than the predetermined wind speed, and the nacelle is misaligned with respect to the wind direction. The actuator can be triggered when the grid loss event is detected in combination with the nacelle being misaligned and the high wind speed. The actuator can be powered by a power storage system, such as a battery or a high pressure gas storage, which allows the actuator to move the wind flow deflector devices from the rest position to the deployed position during the grid loss event.

[0133] In some examples, the power storage system can comprise a battery and / or a super capacitor. The power storage system can be a backup power system for temporarily providing power to the wind turbine components. For example, the actuator can be triggered by a backup power system of the pitch system. The backup power system of the pitch system can comprise a battery and / or a super capacitor. In some examples, the actuator can be triggered by a dedicated power storage system.

[0134] In some examples, the actuator can comprise an electromagnet that holds the plate of the wind flow deflector device in the rest position. During the grid loss event, no power is supplied to the electromagnet and the plate can then be (automatically) deployed.

[0135] Thus, the wind flow deflector devices can be prevented from being deployed when the wind direction and the longitudinal axis of the nacelle are aligned or at a low wind speed.

[0136] During the grid loss event, the wind direction can change and the nacelle can thus be misaligned. Because the nacelle cannot be rotated to follow the change in wind direction, the triggered wind flow deflector devices can reduce the drag of the nacelle to reduce the load acting on the wind turbine.

[0137] In some examples, the method 400 can include determining a duration of the grid loss event. Accordingly, the deployment of the wind flow deflector device can also take into account the duration of the grid loss event. For example, the wind flow deflector device can only move from the rest position to the deployed position if the duration of the grid loss event is longer than a predetermined duration. According to this aspect, short grid loss events do not deploy the wind flow deflector device. The one or more electromagnets can hold the wind flow deflector device in the rest position when power is supplied to it. When no power is supplied to the electromagnets, the wind flow deflector device is allowed to deploy. During the time period in the grid loss event, the energy storage system can still provide power to the electromagnets. However, if this time period is shorter than the duration of the grid loss event, no more power is supplied to the electromagnets. The wind flow deflector device can then be allowed to move from the rest position to the deployed position.

[0138] In some examples, the power or energy storage system can trigger the actuator after a predetermined time period to prevent the wind flow deflector device from moving in short grid loss events.

[0139] This written description uses examples to disclose the application, including the preferred embodiments, and also to enable any person skilled in the art to practice the application, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the application is defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. Aspects from the various embodiments described can be combined to form additional embodiments, and other aspects known to those skilled in the art can also be added to the embodiments without departing from the scope of the application. If a reference symbol placed in a claim in a parenthesis refers to a figure, it is only intended to attempt to increase the intelligibility of the claim, and should not be construed as limiting the scope of the claim.

Claims

1. A nacelle assembly (200) for a wind turbine, the nacelle assembly (200) being connected to a wind turbine tower by a yaw system and having a front region (13) coupled to a rotor (5) comprising a rotor hub (6) and at least one rotor blade (7), the nacelle assembly (200) comprising: a nacelle (4) having a cover structure (50) accommodating wind turbine components, the cover structure (50) comprising a front side (51) arranged at the front region (13), a rear side (52) opposite the front side (51), a first side (61) and a second side (62), and a top side (70) and a bottom side (80); the cover structure extending along a longitudinal axis (31) from the front side (51) to the rear side (52); and the nacelle assembly further comprising: an additional wind flow deflector system (100) coupled to an outer side of the cover structure (50) to direct wind flowing towards the nacelle (4) for reducing drag of the nacelle (4) when in a yaw system failure event the wind direction is misaligned relative to the longitudinal axis (31), the additional wind flow deflector system comprising a wind flow deflector device, wherein the wind turbine is configured to: detect a yaw system failure event; determine whether the nacelle is misaligned relative to the wind direction; determine whether a wind speed is above a predetermined wind speed; and trigger the wind flow deflector device by moving the wind flow deflector device from a rest position to a deployed position when a yaw system failure event is detected, the wind speed is above a predetermined wind speed, and the nacelle is misaligned relative to the wind direction. the yaw system failure event comprises a grid loss event. the additional wind flow deflector system (100) comprises a plurality of wind flow deflector devices (110).

2. The nacelle assembly (200) according to claim 1, characterized in that, at least one of the wind flow deflector devices covers a portion of a first top edge region (71) formed between the top side (70) and the first side (61) and / or a portion of a second top edge region (72) formed between the top side (70) and the second side (62).

3. The nacelle assembly (200) according to claim 1 or 2, characterized in that, at least one of the wind flow deflector devices covers a portion of the first side (61) and / or a portion of the second side (62).

4. The nacelle assembly (200) according to claim 3, characterized in that, at least one of the wind flow deflector devices comprises a plate (113) extending from a proximal end (111) connected to the cover structure (50) to a free distal end (112).

5. The nacelle assembly (200) according to claim 3, characterized in that, the proximal end (111) is connected to one of the first side (61) and the second side (62), forming an acute angle between the plate (113) and the one side.

6. The nacelle assembly (200) according to claim 3, characterized by, the proximal end (111) is connected to the cover structure (50) at a top edge region formed between the top side (70) and one of the first side (61) and the second side (62), forming an acute angle between the plate (113) and the one side.

7. The nacelle assembly (200) according to claim 6, characterized in that, the plate (113) is hingedly connected to the cover structure (50).

8. The nacelle assembly (200) according to claim 6, characterized in that, the plate (113) is curved.

9. The nacelle assembly (200) according to any one of claims 6-8, characterized by, ​ 10. The nacelle assembly (200) according to any one of claims 6-8, characterized by, ​ 11. The nacelle assembly (200) according to claim 10, characterized by, A free distal end (112) of the plate (113) faces the cover structure (50).

12. The nacelle assembly (200) according to claim 3, characterized by, At least one of the wind flow deflector devices comprises a reinforcement structure.

13. The nacelle assembly (200) according to claim 12, characterized by, The reinforcement structure is a strut (130) connected to the cover structure (50).

14. A wind turbine (1) comprising: a tower (2); a nacelle assembly (200) according to any of the claims 1-13 mounted on the tower (2); a yaw system (20) rotatably connecting the nacelle assembly (200) to the tower (2); and a rotor (5) comprising a rotor hub (6) and at least one rotor blade (7), the rotor (5) being arranged at a front region (13) of the nacelle assembly (200).

15. A method (300) for reducing loads in a wind turbine comprising a nacelle assembly during a yaw system failure event, the nacelle assembly comprising a nacelle having a cover structure, wind flow deflector devices coupled to an outer side of the cover structure, the method (300) comprising: detecting (310) a yaw system failure event; determining whether the nacelle is misaligned with respect to a wind direction; determining whether a wind speed is above a predetermined wind speed; and triggering the wind flow deflector devices by moving the wind flow deflector devices from a rest position to a deployed position when a yaw system failure event is detected, the wind speed is above a predetermined wind speed and the nacelle is misaligned with respect to a wind direction.

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