Nacelle roof panel management system for wind turbines

Abstract

A roof panel lifting apparatus for lifting and moving a roof panel of a nacelle of a wind turbine involves: a stationary frame rigidly connectable to the nacelle; and, a movable frame pivotally connected to the stationary frame. The roof panel lifting apparatus together with a lifting device connected to the movable frame of the roof panel lifting apparatus provides a system for management of nacelle roof panels, which is useable in a method of managing a nacelle roof panel.

Description

[0001] NACELLE ROOF PANEL MANAGEMENT SYSTEM FOR WIND TURBINES

[0002] Cross-reference to Related Applications

[0003] This application claims the benefit of USSN 63 / 736,149 filed December 19, 2024, the entire contents of which are herein incorporated by reference.

[0004] Field

[0005] This application relates to wind turbines, in particular to systems for managing opening and closing of nacelle roof panels.

[0006] Background

[0007] Wind turbines often comprise a tower having a nacelle atop the tower to contain wind turbine components such as a generator, a gearbox, a main shaft and the like. The nacelle encloses the wind turbine components to shelter the components from the weather and avian animals. The nacelle is usually equipped with one or more removable roof panels so that the wind turbine components can be accessed for maintenance or replacement, such access often including using a crane to lift components into and out of the nacelle through an opening created by removing one or more of the roof panels. On removing a roof panel of the nacelle, the roof panel is usually lowered to the base of the tower by a crane to store the roof panel while operations are conducted in the nacelle. However, lowering roof panels to the base of the tower may be impossible in certain terrains, such as for offshore wind turbines, and is at least difficult and / or time-consuming and / or weather restricted, even when it is possible to store the roof panel at the base of the tower or on the deck of a nearby jack-up barge or vessel. A crane could be used to hold the roof panel up- tower during operations in the nacelle. However, such an arrangement essentially prevents an up-tower crane from being used for other operations, which is unsuitable given that few cranes can be used up-tower at any given time. Further, a crane on a nearby jack-up barge or other vessel adds expense to the operation, which is undesirable.

[0008] Thus, there remains a need for a system for managing opening and closing of nacelle roof panels atop a wind turbine whereby the roof panels can be stored up-tower during operations in the nacelle.

[0009] Summary

[0010] A method of managing a nacelle roof panel of a nacelle of a wind turbine, the nacelle comprising a first roof panel positioned horizontally adjacent a second roof panel when the nacelle is closed, the method comprising: opening the nacelle by: detaching the second roof panel from the nacelle; lifting the second roof panel; and, stacking the second roof panel over the first roof panel; or, closing the nacelle by: unstacking the second roof panel from over the first roof panel; lifting the second roof panel; and, attaching the second roof panel to the nacelle in a position horizontally adjacent the first roof panel.

[0011] A roof panel lifting apparatus for lifting and moving a roof panel of a nacelle of a wind turbine comprises: a stationary frame rigidly connectable to the nacelle; and, a movable frame pivotally connected to the stationary frame.

[0012] A system for management of a roof panel of a nacelle of a wind turbine comprises: a roof panel lifting apparatus comprising: a stationary frame rigidly connected to the nacelle; and, a movable frame pivotally connected to the stationary frame; and, a lifting device connected to the movable frame of the roof panel lifting apparatus.

[0013] In some embodiments, the movable frame is pivotable between an extended position horizontally adjacent the stationary frame and a retracted position vertically adjacent the stationary frame. In some embodiments, the second roof panel remains horizontally oriented while pivoting between the extended position and the retracted position. In some embodiments, the movable frame remains horizontally oriented when pivoting on the stationary frame while following an arcuate path between the extended position and the retracted position. In some embodiments, the second roof panel is nonhorizontally oriented while pivoting between the extended position and the retracted position. In some embodiments, the movable frame is non-horizontally oriented when pivoting on the stationary frame while following an arcuate path between the extended position and the retracted position. In some embodiments the second roof panel follows an arcuate path while being lifted between the position horizontally adjacent the first roof panel and a position stacked over the first roof panel. In some embodiments, a lower face of the second roof panel faces an upper face of the first roof panel when the second roof panel is stacked over the first roof panel.

[0014] In some embodiments, the stationary frame comprises a plurality of interconnected elongated frame elements. In some embodiments, some of the elongated frame elements of the stationary frame form a base that rests on the first roof panel of the nacelle when the roof panel lifting apparatus is in use. In some embodiments, the movable frame comprises a plurality of interconnected elongated frame elements. In some embodiments, some of the elongated frame elements of the movable frame form a base that contacts a top of the second roof panel of the nacelle when the roof panel lifting apparatus is in use. In some embodiments, the stationary frame and / or the movable frame are connected to upper surfaces of respective roof elements by fasteners, for example, screws, bolts, clamps and the like.

[0015] In some embodiments, the movable frame is pivotally connected to the stationary frame through a four-bar linkage. In some embodiments, the movable frame is pivotally connected to the stationary frame through a first four-bar linkage and a second four-bar linkage horizontally separated from the first four-bar linkage. In some embodiments, the first four-bar linkage and the second four-bar linkage are horizontally separated from each other in a horizontal direction perpendicular to the horizontal direction in which the movable frame pivots. In some embodiments, the four-bar linkages are situated at respective ends of the roof panel lifting apparatus. In some embodiments, each of the four-bar linkages is pivotably connected to the stationary frame and the movable frame by pivot pins. In some embodiments, the pivot pins are mounted on elongated frame elements of the stationary and movable frames. In some embodiments, the four-bar linkages are parallelogram linkages. In some embodiments, the four-bar linkages are also connected to the stationary frame through one or more pivoting braces. In some embodiments, the pivoting braces are pivotably mounted to one or more of the elongated frame elements. The one or more pivoting braces provide further stability to the four-bar linkages, especially when the movable frame is in the retracted position and carrying the weight of the second roof panel.

[0016] In some embodiments, the stationary frame further comprises horizontally spacedapart roof panel supports. In some embodiments, the roof panel supports comprise vertically oriented posts with horizontally oriented projecting arms upon which the second roof panel is supported when the movable frame, with the second roof panel secured thereto, is lifted into the retracted position.

[0017] In some embodiments, guideposts extending upward from the nacelle permit indexing of the stationary frame to a pre-determined location on the nacelle. In some embodiments, guideposts extending upward from the upper surface of the first roof panel permit indexing the stationary frame to a proper location on the first roof panel. In some embodiments, the guideposts are received by indexed receivers (e.g., apertures) in the stationary frame at suitable locations to receive the guideposts when mounting the roof panel lifting apparatus on the nacelle.

[0018] In some embodiments, the roof panel lifting apparatus further comprises a counterweight positioned on the movable frame at a location that shifts a center of gravity of the apparatus, in relation to a geometric center of the apparatus, toward an end of the apparatus.

[0019] In some embodiments, the movable frame comprises a lifting lug located on one of the elongated frame elements. The lifting lug provides an attachment structure to which a lifting line of the lifting device is attachable.

[0020] In some embodiments, the lifting device comprises a crane, a winch, an actuator (e.g., a hydraulic cylinder, a pneumatic cylinder, an electric linear actuator, a mechanical actuator (e.g., a cranked ratchet wheel with a pawl), any combination thereof, or any other suitable lifting device. In some embodiments, the lifting device is an up-tower lifting device mounted atop the wind turbine. In some embodiments, the lifting device is mounted on a jack-up vessel.

[0021] Further features will be described or will become apparent in the course of the following detailed description. It should be understood that each feature described herein may be utilized in any combination with any one or more of the other described features, and that each feature does not necessarily rely on the presence of another feature except where evident to one of skill in the art.

[0022] Brief Description of the Drawings

[0023] For clearer understanding, preferred embodiments will now be described in detail by way of example, with reference to the accompanying drawings, in which:

[0024] Fig. 1 depicts a perspective view of a roof panel lifting apparatus in an extended configuration.

[0025] Fig. 2 depicts a side view of the roof panel lifting apparatus of Fig. 1.

[0026] Fig. 3 depicts a top view of the roof panel lifting apparatus of Fig. 1 .

[0027] Fig. 4 depicts a perspective view of the roof panel lifting apparatus of Fig. 1 in a retracted configuration.

[0028] Fig. 5 depicts a side view of the roof panel lifting apparatus of Fig. 4.

[0029] Fig. 6 depicts a top view of the roof panel lifting apparatus of Fig. 4.

[0030] Fig. 7A depicts a perspective view of a first step in a method of managing a nacelle roof panel of a nacelle of a wind turbine. Fig. 7B depicts a side view of Fig. 7A.

[0031] Fig. 7C depicts a top view of a rear portion of Fig. 7A.

[0032] Fig. 8A depicts a perspective view of a second step in the method of managing a nacelle roof panel of a nacelle of a wind turbine.

[0033] Fig. 8B depicts a side view of Fig. 8A.

[0034] Fig. 8C depicts a top view of a rear portion of Fig. 8A.

[0035] Fig. 9A depicts a perspective view of a third step in the method of managing a nacelle roof panel of a nacelle of a wind turbine.

[0036] Fig. 9B depicts a side view of Fig. 9A.

[0037] Fig. 9C depicts a top view of a rear portion of Fig. 9A.

[0038] Fig. 10A depicts a perspective view of a fourth step in the method of managing a nacelle roof panel of a nacelle of a wind turbine.

[0039] Fig. 10B depicts a side view of Fig. 10A.

[0040] Fig. 10C depicts a top view of a rear portion of Fig. 10A.

[0041] Fig. 11A depicts a perspective view of a fifth step in the method of managing a nacelle roof panel of a nacelle of a wind turbine.

[0042] Fig. 11 B depicts a side view of Fig. 11 A.

[0043] Fig. 11C depicts a top view of a rear portion of Fig. 11A.

[0044] Fig. 12A depicts a perspective view of a sixth step in the method of managing a nacelle roof panel of a nacelle of a wind turbine.

[0045] Fig. 12B depicts a side view of Fig. 12A.

[0046] Fig. 12C depicts a top view of a rear portion of Fig. 12A.

[0047] Fig. 13A depicts a perspective view of a seventh step in the method of managing a nacelle roof panel of a nacelle of a wind turbine.

[0048] Fig. 13B depicts a side view of Fig. 13A. Fig. 13C depicts a top view of a rear portion of Fig. 13A.

[0049] Detailed Description

[0050] Fig. 1 to Fig. 6 depict a roof panel lifting apparatus 1 for lifting a roof panel of a nacelle of a wind turbine, where the nacelle comprises a first roof panel positioned horizontally adjacent a second roof panel when the nacelle is closed. The roof panel lifting apparatus 1 comprises a stationary frame 10 rigidly connectable to the nacelle, and a movable frame 30 pivotally connected to the stationary frame 10. The stationary frame 10 comprises a plurality of interconnected elongated frame elements, some of which form a base 20 that rests on the first roof panel of the nacelle when the roof panel lifting apparatus 1 is in use. The movable frame 30 also comprises a plurality of interconnected elongated frame elements, some of which form a base 40 that contacts a top of the second roof panel of the nacelle when the roof panel lifting apparatus 1 is in use.

[0051] The stationary frame 10 is removably and rigidly connectable to the nacelle, for example to the first roof panel, by fasteners. The fasteners may be, for example, screws, bolts, clamps and the like. In the illustrated embodiment, the fasteners comprise bolts inserted through apertures in one or more of the frame elements, or in one or more flanges connected to the one or more frame elements, of the stationary frame 10 to engage with threaded apertures either in an upper surface of the first roof panel or in guideposts extending upward from the upper surface of the first roof panel. The use of guideposts extending upward from the upper surface of the first roof panel permits indexing the stationary frame 10 to a proper location on the first roof panel by providing indexed receivers (e.g., apertures) in the stationary frame 10 at suitable locations to receive the guideposts when mounting the roof panel lifting apparatus 1 on the nacelle.

[0052] The movable frame 30 is pivotable between an extended position (see Fig. 1 to Fig. 3) horizontally adjacent the stationary frame 10 and a retracted position (see Fig. 4 to Fig. 6) vertically adjacent the stationary frame 10. When the movable frame 30 is in the extended position, the movable frame 30 is removably and rigidly connectable, by fasteners, for example screws, bolts, clamps and the like to the second roof panel, which is the roof panel to be lifted. In the illustrated embodiment, the movable frame 30 is removably and rigidly connectable to the second roof panel by bolts inserted through bolt holes 33 in frame elements 35 of the movable frame 30. The bolts engage threaded apertures in an upper surface of the second roof panel to removably secure the movable frame 30 to the second roof panel. The movable frame 30 is pivotally connected to the stationary frame 10 through a first four-bar linkage 51 and a second four-bar linkage 52. The first four-bar linkage 51 and the second four-bar linkage 52 are horizontally separated from each other in a horizontal direction perpendicular to the horizontal direction in which the movable frame pivots, the four-bar linkages 51 , 52 being situated at respective ends of the roof panel lifting apparatus 1.

[0053] The first four-bar linkage 51 comprises a first upper link 53 and a first lower link 55. The first upper link 53 and the first lower link 55 are each pivotably connected to the stationary frame 10 by pivot pins 57 and 59, respectively. The pivot pin 57 is mounted on a first vertically extending strut 11 of the stationary frame 10 and the pivot pin 59 is mounted on a first horizontally extending strut 13 of the stationary frame 10, where the first horizontally extending strut 13 is rigidly connected to and extends horizontally from the first vertically extending strut 11 so that the pivot pin 57 is vertically higher than the pivot pin 59 and the struts 11 and 13 form a link of the first four-bar linkage 51. The first upper link 53 and the first lower link 55 are each also pivotably connected to the movable frame 30 by pivot pins 61 and 63, respectively. The pivot pin 61 is mounted on one end of a first pivoting strut 31 of the movable frame 30 and the pivot pin 63 is mounted on another end of the first movable strut 31 of the movable frame 30, so that the pivot pin 61 is vertically higher than the pivot pin 63 and the strut 31 forms a link of the first four-bar linkage 51.

[0054] Likewise, the second four-bar linkage 52 comprises a second upper link 54 and a second lower link 56. The second upper link 54 and the second lower link 56 are each pivotably connected to the stationary frame 10 by pivot pins 58 and 60, respectively. The pivot pin 58 is mounted on a second vertically extending strut 12 of the stationary frame 10 and the pivot pin 60 is mounted on a second horizontally extending strut 14 of the stationary frame 10, where the second horizontally extending strut 14 is rigidly connected to and extends horizontally from the second vertically extending strut 12 so that the pivot pin 58 is vertically higher than the pivot pin 60 and the struts 12 and 14 form a link of the second four-bar linkage 52. The second upper link 54 and the second lower link 56 are each also pivotably connected to the movable frame 30 by pivot pins 62 and 64, respectively. The pivot pin 62 is mounted on one end of a second pivoting strut 32 of the movable frame 30 and the pivot pin 64 is mounted on another end of the second movable strut 32 of the movable frame 30, so that the pivot pin 62 is vertically higher than the pivot pin 64 and the strut 32 forms a link of the second four-bar linkage 52.

[0055] In the illustrated embodiment, the four-bar linkages 51 , 52 are functionally parallelogram linkages because the upper and lower links 53, 54, 55, 56 all have the same length, the pivoting struts 31 , 32 have the same length, straight line distances between the pivot pins 57, 59 and between the pivot pins 61 , 63 are the same, and straight line distances between the pivot pins 58, 60 and between the pivot pins 62, 64 are the same as between the pivot pins 57, 59 and the pivot pins 61 , 63, respectively. In the illustrated embodiment, the movable frame 30 always remains horizontally oriented when pivoting on the stationary frame 10 while following an arcuate path between the extended position and the retracted position. However, by changing the lengths of the four-bar linkages 51 , 52, the movable frame 30 can be in a non-horizontal orientation while following an arcuate path between the extended position and the retracted position.

[0056] To provide further stability to the four-bar linkages 51 , 52, especially when the movable frame 30 is in the retracted position and carrying the weight of the second roof panel, the four-bar linkages 51 , 52 are also connected to the stationary frame 10 through pivoting braces 65 and 66, respectively. The pivoting braces 65, 66 are pivotably mounted to frame elements 15 and 16, respectively, of the stationary frame 10 through 17 and 18, respectively. The pivoting braces 65, 66 are rigidly connected to the lower links 55, 56, respectively, of the first and second four-bar linkages 51 and 52, respectively. The pivoting braces 65, 66 are rigidly connected to the lower links 55, 56 proximate center points of the respective lower links 55, 56. As the lower links 55, 56 pivot on the pivot pins 59, 60, respectively, the pivoting braces 65, 66 pivot in tandem with the lower links 55, 56.

[0057] The stationary frame 10 further comprises horizontally spaced-apart roof panel supports 21 , 22 comprising vertically oriented posts 23, 24, respectively, with horizontally oriented projecting arms 25, 26, respectively, upon which the second roof panel is supported when the movable frame 30, with the second roof panel secured thereto, is lifted into the retracted position.

[0058] The movable frame 30 comprises a lifting lug 37 located on one of the frame elements of the base 40. A lifting device (e.g., a crane, a winch or an actuator) is connectable to the lifting lug 37 through a lifting line, and the lifting device is operable to lift the movable frame 30. If the stationary frame 10 is not secured to the nacelle, lifting the movable frame 30 lifts the entire apparatus 1. If the stationary frame 10 is secured to the nacelle, lifting the movable frame 30 moves the movable frame 30 between the retracted and extended positions. If the stationary frame 10 is secured to the nacelle and the second roof panel is connected to the movable frame 30 and disconnected from the nacelle, lifting movable frame 30 moves the movable frame 30 between the extended and retracted positions and moves the second roof panel between a closed position on the nacelle and an open stored position where the second roof panel is supported on the roof panel supports 21 , 22 of the stationary frame 10. Pivoting of the movable frame 30 between the extended and retracted positions can be prevented by locks (not shown) that immovably secure the movable frame 30 to the stationary frame 10. The locks may be clamps, pinned connections, straps, or the like. Thus, the roof panel lifting apparatus 1 permits roof panels to be stored up-tower during other operations in the nacelle without the need to continuously occupy the services of a lifting device during the operations in the nacelle.

[0059] The roof panel lifting apparatus 1 further comprises a counterweight 39 positioned on and secured to one or more frame elements of the movable frame 10 at a location that shifts a center of gravity of the apparatus 1 , in relation to a geometric center of the apparatus 1 , toward an end of the apparatus 1. The counterweight 39 serves to provide sufficient tension in the lifting line of the lifting device and to compensate for the location of the lifting device, especially an up-tower lifting device mounted in the nacelle at a location horizontally separated from the roof panel to be lifted, to ensure that the roof panel lifting apparatus 1 remains level during a lifting operation, especially when the stationary frame 10 is not secured to the nacelle.

[0060] Fig. 7A to Fig. 13C illustrates a method of managing a nacelle roof panel of a nacelle 2 of a wind turbine utilizing a system comprising the roof panel lifting apparatus 1 and an up-tower crane 90. The sequence of Fig. 7A to Fig. 13C illustrates opening the roof panel. Closing the roof panel is accomplished by reversing the steps.

[0061] The nacelle 2 sits atop a tower 3 of the wind turbine. The illustrated nacelle 2 comprises four roof panels including a first roof panel 71 , a second roof panel 72, a third roof panel 73 and a fourth roof panel 74. The third and fourth roof panels 73, 74 are transversely horizontally adjacent to each other and cover a forward section of the nacelle 2 and open by swinging up to a vertical orientation at opposed sides of the nacelle 2. The crane 90 is mounted up-tower in the nacelle 2 in the forward section. As can be seen in Fig. 7A, for example, the third and fourth roof panels 73, 74, when opened, block access into the nacelle 2 at respective sidewalls which they abut because the third and fourth roof panels 73, 74 extend vertically upward from upper edges of the respective sidewalls of the nacelle 2.

[0062] The first and second roof panels 71 , 72 are transversely horizontally adjacent to each other and cover a rear section of the nacelle 2. The first and second roof panels 71 , 72 are designed to be opened by being lifted entirely off the nacelle 2 and being placed in a storage location away from respective sidewalls of the nacelle 2 which each abut. Further, the first and second roof panels 71 , 72 have downwardly extending side portions (for example, downwardly extending portion 75 of the second roof panel 72) so that the upper edges of the sidewalls of the nacelle 2 are lower in the rear section than in the forward section of the nacelle 2. Thus, when the first and / or second roof panels 71 , 72 are opened, an operator has easier access into the rear section from the sides of the nacelle 2 for removal and installation of wind turbine components, for example a generator 99.

[0063] Referring to Fig. 7A to Fig. 7C, a first step in a method for opening the second roof panel 72 involves using the crane 90 to lift the roof panel lifting apparatus 1 from downtower to up-tower and then position the roof panel lifting apparatus 1 on an upper surface of the first roof panel 71 so that the roof panel lifting apparatus 1 is oriented with the ends forward and rearward, and the end with the counterweight 39 is closer to the crane 90. The movable frame 30 of the roof panel lifting apparatus 1 is in the retracted position and is secured to the stationary frame 10 during the lifting and positioning process to prevent the movable frame 30 from pivoting from the retracted position to the extended position. The crane 90 is connected to the movable frame 30 through a lifting line 91 attached to the lifting lug 37 of the movable frame 30, although the crane 90 could be connected directly to the movable frame 30 without a lifting line. The crane 90 is operated to place the roof panel lifting apparatus 1 on the first roof panel 71 with the aid of guideposts 76 that protrude upwardly from the first roof panel 71 , and which cooperate with apertures in a bottom of the stationary frame 10 to correctly position the stationary frame 10 on the first roof panel 71. With the roof panel lifting apparatus 1 placed on the first roof panel 71 , the stationary frame 10 is secured to the first roof panel 71 , for example with bolts, to immobilize the stationary frame 10 on the first roof panel 71. Pads may be placed between the stationary frame 10 and the first roof panel 71 to protect the first roof panel 71 from damage.

[0064] Referring to Fig. 8A to Fig. 8C, a second step in the method involves removing securement of the movable frame 30 to the stationary frame 10 to permit pivoting of the movable frame 30 from the retracted position to the extended position. The crane 90 is operated to cause the movable frame 30 to start pivoting from the retracted position toward the extended position. As seen in Fig. 8B, during the pivoting of the movable frame 30, the movable frame 30 remains horizontally oriented as the movable frame 30 pivots through an arc.

[0065] Referring to Fig. 9A to Fig. 9C, a third step in the method involves using the crane 90 to continue pivoting of the movable frame 30 until the movable frame 30 is lowered to the second roof panel 72 to finally rest on an upper surface of the second roof panel 72 where the movable frame 30 is transversely horizontally directly adjacent the stationary frame 10. It is evident from the progression shown in Fig. 7B to Fig. 8B to Fig. 9B that the movable frame 30 follows an arcuate path from the retracted position (Fig. 7A) to the extended position (Fig. 9B). Once the movable frame 30 is in the extended position resting on the second roof panel 72, the movable frame 30 is secured to the second roof panel 72, for example with bolts. Pads may be placed between the movable frame 30 and the second roof panel 72 to protect the second roof panel 72 from damage.

[0066] Referring to Fig. 10A to Fig. 10C, a fourth step in the method involves unlocking the second roof panel 72 from the nacelle 2 and using the crane 90 to lift the movable frame 30 with the second roof panel 72 secured thereto thereby vertically separating the second roof panel 72 from the nacelle 2.

[0067] Referring to Fig. 11A to Fig. 1 1 C, a fifth step in the method involves using the crane 90 to lift the movable frame 30, with the second roof panel 72 secured thereto, toward the retracted position. The movable frame 30, with the second roof panel 72 secured thereto, pivots through the arcuate path with the movable frame 30 and the second roof panel 72 remaining horizontally oriented in the illustrated embodiment.

[0068] Referring to Fig. 12A to Fig. 12C, a sixth step in the method involves continuing to lift the movable frame 30, with the second roof panel 72 secured thereto, the movable frame 30 pivoting toward the retracted position. At this point, the center of gravity of the movable frame 30 passes through a vertical plane defining a center of gravity of the four bar linkages 51 , 52.

[0069] Referring to Fig. 13A to Fig. 13C, a seventh step in the method involves continuing to lift the movable frame 30, with the second roof panel 72 secured thereto, into the retracted position. With the movable frame 30 in the retracted position, the second roof panel 72 is supported on the roof panel supports 21 , 22 (see Fig. 12A and Fig. 12C) of the stationary frame 10 and stacked over the first roof panel 71. The movable frame 30 is once again secured to the stationary frame 10 to prevent pivoting of the movable frame 30, which permits the lifting line 91 to be detached from the lifting lug 37 so that the crane 90 can be used for other tasks, for example lifting the generator 99. The second roof panel 72 is stored away from the side of the nacelle 2, which the second roof panel 72 normally abuts providing greater access into the nacelle 2 from that side.

[0070] The roof panel lifting apparatus 1 permits storing the second roof panel 72 at an up- tower location, saving time usually needed to lower and raise the second roof panel 72 between up-tower and down-tower locations. This is particularly advantageous for off-shore wind turbines where there is often no down-tower location where a roof panel can be stored, and where high wind speeds can create significant problems with lifting components between up-tower and down-tower locations.

[0071] The novel features will become apparent to those of skill in the art upon examination of the description. It should be understood, however, that the scope of the claims should not be limited by the embodiments but should be given the broadest interpretation consistent with the wording of the claims and the specification as a whole.

Claims

Claims:1 . A method of managing a nacelle roof panel of a nacelle of a wind turbine, the nacelle comprising a first roof panel positioned horizontally adjacent a second roof panel when the nacelle is closed, the method comprising: opening the nacelle by: detaching the second roof panel from the nacelle; lifting the second roof panel; and, stacking the second roof panel over the first roof panel; or, closing the nacelle by: unstacking the second roof panel from over the first roof panel; lifting the second roof panel; and, attaching the second roof panel to the nacelle in a position horizontally adjacent the first roof panel.

2. The method of claim 1 , wherein the second roof panel remains horizontally oriented when being lifted while following an arcuate path between the position horizontally adjacent the first roof panel and a position stacked over the first roof panel.

3. The method of claim 1 , wherein the second roof panel is non-horizontally oriented when being lifted while following an arcuate path between the position horizontally adjacent the first roof panel and a position stacked over the first roof panel.

4. The method of any one of claims 1 to 3, wherein a lower face of the second roof panel faces an upper face of the first roof panel when the second roof panel is stacked over the first roof panel.

5. A roof panel lifting apparatus for lifting and moving a roof panel of a nacelle of a wind turbine, the roof panel lifting apparatus comprising: a stationary frame rigidly connectable to the nacelle; and, a movable frame pivotally connected to the stationary frame.

6. The roof panel lifting apparatus of claim 5, wherein the movable frame is pivotable between an extended position horizontally adjacent the stationary frame and a retracted position vertically adjacent the stationary frame.

7. The roof panel lifting apparatus of claim 6, wherein the movable frame remains horizontally oriented when pivoting on the stationary frame while following an arcuate path between the extended position and the retracted position.

8. The roof panel lifting apparatus of claim 6, wherein the movable frame is nonhorizontally oriented when pivoting on the stationary frame while following an arcuate path between the extended position and the retracted position.

9. The roof panel lifting apparatus of any one of claims 5 to 8, wherein the movable frame is pivotally connected to the stationary frame through a four-bar linkage.

10. The roof panel lifting apparatus of any one of claims 5 to 8, wherein the movable frame is pivotally connected to the stationary frame through a first four-bar linkage and a second four-bar linkage horizontally separated from the first four-bar linkage.11 . The roof panel lifting apparatus of any one of claims 5 to 10, further comprising a counterweight positioned on the movable frame at a location that shifts a center of gravity of the apparatus, in relation to a geometric center of the apparatus, toward an end of the apparatus.

12. A system for management of a roof panel of a nacelle of a wind turbine, the system comprising: a roof panel lifting apparatus as defined in any one of claims 5 to 11 , wherein the stationary frame is rigidly connected to the nacelle; and, a lifting device connected to the movable frame.

13. The system of claim 12, wherein the lifting device comprises a crane.

14. The system of claim 12 or claim 13, wherein the lifting device is up-tower, mounted in the nacelle, or wherein the lifting device is mounted on a jack-up vessel.

15. The system of any one of claims 12 to 14, further comprising guideposts extending upward from the nacelle, the guideposts permitting indexing of the stationary frame to a pre-determined location on the nacelle.

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