WO2019229081A1

WO2019229081A1 - Geared transmission device and operating method thereof in case of gear damage

Info

Publication number: WO2019229081A1
Application number: PCT/EP2019/063863
Authority: WO
Inventors: Tomohiro Numajiri
Original assignee: Mhi Vestas Offshore Wind A/S
Priority date: 2018-05-29
Filing date: 2019-05-28
Publication date: 2019-12-05

Abstract

A power transmission device, comprising: a plurality of driving machines each of which has a pinion gear; a gear member which includes a damaged portion and engages with the plurality of pinion gears; and a controller which individually controls the plurality of driving machines. The driving machine is defined as being in a first state when disposed to engage with the gear member in a predetermined region including the damaged portion, and is defined as being in a second state when disposed to engage with the gear member in a region other than the predetermined region. The controller is configured to set torque to be generated by the driving machine of the first state to a low level, which is lower than the torque generated by the driving machine of the second state.

Description

DESCRIPTION

GEARED TRANSMISSION DEVICE AND OPERATING METHOD THEREOF IN

CASE OF GEAR DAMAGE

TECHNICAL FIELD

[0001] This disclosure relates to a power transmission device and an operating method thereof.

BACKGROUND

[0002] Conventionally, there is known a configuration in which operating condition of a wind turbine is limited in accordance with environmental conditions. For example, US Patent Publication No. 2016/0341179 (hereinafter referred to as Patent Document 1) discloses a configuration that uses a derating scheme based on environmental conditions (for example, temperature, altitude, air density, wind speed, etc.) to determine an operation limit of components of a wind turbine, and controls an operating condition of the wind turbine so that an operation parameter (for example, electric current) of the wind turbine does not exceed the determined operation limit.

[0003] The above-mentioned Patent Document 1 attempts to improve the power generation efficiency by operating the wind turbine at a power exceeding the rated output or below the rated output mainly by determining the operation limit according to environmental conditions. However, in Patent Document 1, no measures or solutions are described regarding an operation of the wind turbine under appropriate operating conditions in consideration of a damage in the case where, for example, at least a part of the components related to the power transmission of the wind turbine is damaged.

SUMMARY

[0004] The present invention has been made in view of the above problems, and at least one embodiment of the present invention aims to determine an appropriate operational condition in consideration of a damage of a power transmission unit. [0005] (1) According to at least one embodiment of the present invention, there is provided a power transmission device, comprising:

a plurality of driving machines each of which has a pinion gear;

a gear member which includes a damaged portion and engages with the plurality of pinion gears; and

a controller which individually controls the plurality of driving machines,

wherein the driving machine is defined as being in a first state when disposed to engage with the gear member in a predetermined region including the damaged portion, and is defined as being in a second state when disposed to engage with the gear member in a region other than the predetermined region, and

wherein the controller is configured to set torque to be generated by the driving machine of the first state to a low level, which is lower than the torque generated by the driving machine of the second state.

[0006] According to the above configuration (1), it is possible to reduce the stress acting on the damaged portion of the gear member from the pinion gear of the driving machine in the first state. Therefore, appropriate operation conditions can be determined in consideration of the damage of the power transmission portion. Thereby, it is possible to reduce the risk of damage expansion and consequential damage occurrence to the damaged portion. Therefore, it is possible to take appropriate service life extension measures on the damaged gear member or the power transmission device.

[0007] (2) In some embodiment, according to the above configuration (1), the controller may be configured to set, if at least one driving machine is in the first state, the torque generated by the driving machine of the second state to a high level, which is higher than the torque generated when all the driving machines are in the second state.

[0008] According to the above configuration (2), the torque reduction of the at least one of the driving machines engaged with the predetermined region including the damaged portion in the gear member can be complemented by one or more driving machine(s). As a result, the necessary torque to be applied to the gear member can be applied by the whole of the plurality of driving machines. Therefore, it is possible to maintain the smooth operation of the power transmission device while reducing the load acting on the damaged portion of the gear member and prolonging the service life of the power transmission device without the need to replace the gear member or by postponing replacement or service to a more advantageous point in time.

[0009] (3) In some embodiment, according to the above configuration (1) or (2), regarding the upper limit of the torque of each of the driving machines, the controller may be configured to

restrict the torque, which is to be generate by the driving machine in the first state disposed opposite at least to the damaged portion, to be equal to or less than a first threshold value which is able to be withstood by the damaged portion, and

set the torque, which is to be generated by the driving machine in the second state, to be greater than the first threshold value and not more than a second threshold value applied to the second state.

[0010] According to the above configuration (3), the driving machine positioned so as to be disposed opposite to the region where at least the damaged portion exists in the gear member is controlled so as to generate a torque equal to or less than the first threshold value which the damaged gear member can withstand without further or excessive damaging the gear member. Therefore, since it is possible to reduce the load on the damaged gear member at least against the damaged portion to protect the gear member, it is possible to take appropriate service life extension measures for the gear member and thus for the power transmission device for example so service, repair or replace can be prevented or postponed to a more suitable time.

[0011] (4) In some embodiment, according to any one of the above (1) to (3), the controller may be configured to drive the at least one driving machine of the first state with lower torque as the driving machine is closer to the damaged portion.

[0012] According to the above configuration (4), the driving machine positioned opposite to the predetermined region including the damaged portion of the gear member is driven with lower torque as it is closer to the damaged portion. That is, as the relative distance between the damaged portion of the gear member and the driving machine becomes closer, the driving machine is driven with lower torque, and at the phase where the damaged portion exists, it is driven with the lowest torque (including zero). Therefore, it is possible to appropriately reduce the load on the damaged portion while suppressing the sudden torque change of the driving machine, so that appropriate life prolongation measures can be taken to the power transmission device including the damaged gear member.

[0013] (5) In some embodiment, according to any one of the above (1) to (4), the controller may be configured to drive each of the plurality of driving machines to engage with the gear member at a relative speed of zero.

[0014] According to the above configuration (5), when the gear member is partially damaged, the plurality of driving machines are driven so as to mesh with the gear member at a relative speed of zero. Thereby, for example, in the case where a part of the teeth is totally damaged as a damaged form of the damaged portion, the driving machine disposed to engage with the damaged portion can be prevented from increasing its rotational speed due to idle rotation of the pinion gear. Therefore, it is possible to appropriately prevent occurrence of secondary damage to the next tooth or the pinion gear due to the difference in relative speed between the meshing teeth and the pinion gear.

[0015] (6) In some embodiment, according to any one of the above (1) to (5), the damaged portion may include a tooth of the gear member, and

the first threshold value may be set according to a ratio of a tooth width of the tooth of the damaged portion to a tooth width of the tooth in the region other than the predetermined region.

[0016] According to the above configuration (6), the torque transmitted between the pinion gear and the gear member can be set to be limited to a torque level that the remaining teeth can withstand, depending on the damage degree of the damaged portion. Therefore, it is possible to share a part of the torque transmitted between the pinion gear and the gear member within a possible range to the remaining teeth while suppressing an excessive load on the remaining teeth.

[0017] (7) In some embodiment, according to any one of the above (1) to (6), the low level of torque may be defined as a level at which the damaged portion of the gear member is able to maintain a predetermined service life.

[0018] According to the above configuration (7), considering the operation plan, maintenance plan, etc. of the device on which the power transmission device is mounted, the operation of the device can be continued with the load (torque) applied to the damaged portion from the pinion gear of the driving machine engaged with the damaged portion is suppressed, while protecting the damaged portion so that a predetermined service life can be maintained.

[0019] (8) In some embodiment, according to any one of the above (2) to (7), the high- level torque may be defined as a torque which makes the total torque of all of the plurality of driving machines to be the same level as the total torque of all of the plurality of driving machines in the absence of the damaged portion.

[0020] According to the above configuration (8), it is possible to substantially cancel the torque reduction caused by the driving machine meshing with the predetermined area including the damaged portion in the gear member, that is the torque reduction can be compensated by other driving machines. Therefore, since the plural driving machines can cooperatively undertake the necessary torque to be applied to the gear member (or to be transmitted from the gear member), it is possible to effectively maintain smooth operation of the power transmission device while reducing the load to be applied to the damaged portion of the gear member, and prolonging the service life of the power transmission device.

[0021] (9) In some embodiment, according to the above (8), the total torque of all of the plurality of driving machines may be defined as a level at which each of the driving machines in the second state is able to maintain a predetermined endurance life.

[0022] According to the above configuration (9), in consideration of the operation plan, maintenance plan, and the like of the device on which the power transmission device is mounted, it is possible to regulates the load (torque) applied to the gear member from the pinion gear of the driving machines meshing with the normal-state teeth, to continue the operation of the power transmission device so that a predetermined service life can be maintained.

[0023] (10) In some embodiment, according to any one of the above (1) to (9), the power transmission device may include a yaw system of a wind turbine operational between a nacelle and a tower rotatably supporting the nacelle, or a pitch system of a wind turbine blade.

[0024] According to the above configuration (10), when the power transmission device includes the yaw system of the wind turbine, for example, by performing the low level torque control so as to protect the damage (damaged portion) in the ring gear of the wind turbine as described above, it is possible to reduce the risk of damage expansion and secondary damage occurrence in the damaged portion. Therefore, it is possible to take appropriate service life extension measures on the damaged ring gear (the gear member) and the power transmission device.

Further, when the power transmission device includes the pitch system of the wind turbine, for example, when torque is exchanged between the blade root portion of the wind turbine blade and the pinion gear of the pitch drive actuator, it is possible to reduce the risk of damage expansion and secondary damage occurrence in the damaged portion, by performing the low-level torque control so as to protect the damaged portion of the gear member. Therefore, it is possible to take appropriate service life extension measures on the damaged gear member or the power transmission device.

[0025] (11) According to at least one embodiment of the present invention, there is provided a method of operating a power transmission device which includes a gear member, the method comprising:

setting, if the gear member is partially damaged, torque generated by a driving machine in a first state at which the driving machine is disposed to be able to engage with a predetermined region including a damaged portion to be a low level, which is lower than a torque of the driving machine in a second state at which the driving machine is disposed to engage with the gear member in a region other than the predetermined region. [0026] According to the above method (11), as described in the above (1 ), the stress acting on the damaged portion of the gear member from the pinion gear of the driving machine in the first state can be reduced. Therefore, it is possible to determine an appropriate operating condition in consideration of damage of the power transmission section. Since it is possible to reduce the risk of damage to the damaged portion and occurrence of secondary damage, it is possible to take appropriate service life extension measures on the damaged gear member, and thus the power transmission device.

[0027] (12) ln some embodiment, according to the above (11), the method may further comprise:

detecting the damaged portion of the gear member;

measuring the damaged portion;

evaluating a durability level of torque at the damaged part; and

performing an actual operation according to the evaluated durability level.

[0028] According to the above method (12), in consideration of the operation plan, maintenance plan, and the like of the device (for example, a wind turbine) on which the power transmission device is mounted, it is possible to continue the operation while protecting the damaged portion so that the load (torque) applied to the damaged portion from the pinion gear of the driving machine that can engage with the damaged portion can be suppressed and the predetermined service life can be maintained. For example, if the device on which the power transmission device is mounted is a power generation facility including a wind turbine and the like, service of the damaged part (repair or replacement) can be performed, if needed, when timing is more advantageous without having to stop energy production until service can be performed. Allowing for flexible planning of service is particularly advantageous for offshore wind turbines where service is very costly as it typically requires vessel or helicopter for access.

[0029] (13) In some embodiment, according to the above (11) or (12), the method may further comprise:

evaluating remaining capacity or remaining life of the gear member; and determining an allowable torque level based on the evaluated remaining capacity or the remaining life.

[0030] According to the above method (13), the load (torque) exchanged between the pinion gear of the driving machine and the gear member is regulated within an appropriate torque level, and the operation of the power transmission device can be continued so that a predetermined service life can be maintained.

[0031] (14) In some embodiment, according to any one of the above (11) to (13), the method may further comprise:

evaluating remaining capacity or remaining life of the gear member; and

determining the number of cycles to be applied to the damaged area by considering and comparing a relationship between the total storage capacity and the external torque to be supported by a system.

[0032] According to the above method (14), the number of cycles of the load (torque) that may be repeatedly transmitted between the pinion gear of the driving machine and the gear member can be regulated within an appropriate number of times, and the operation of the power transmission device can be continued so that a predetermined service life can be maintained.

[0033] (15) According to at least one embodiment of the present invention, there is provided a use of the power transmission device according to any one of the above (1) to (10) or the method according to any one of the above (11) to (14) for postponing for a period of time, T, service of the partially damaged gear member, wherein the gear member remains operable during the period of time, T.

[0034] According to the above (15), it was found to be particularly advantageous that the embodiments of the invention allowed the gear member to remain operable during the period of time, T, so for example energy production of a wind turbine may be continued even though an important part of the wind turbine such as the yaw system is damaged. Being able to continue operation is particularly advantageous for offshore wind turbines as service may take considerable time to plan and may only be possible to perform at certain (weather) conditions. Furthermore, the production of a wind turbine varies dependent on weather conditions, so being able to postpone service to a time where production is low or zero due to weather conditions is environmentally advantageous as it allows for maximum production of renewable energy and hence reduce the need for non-renewable energy. Furthermore, this also has major financial advantages for the wind turbine owner.

BRIEF DESCRIPTION OF DRAWINGS

[0035] FIG. 1 is a schematic view showing a structure of a wind turbine in one embodiment of the present invention.

FIG. 2 is a schematic perspective view showing a structural example of a power transmission device according to one embodiment of the present invention.

FIG. 3 is a schematic view showing an arrangement example of a power transmission device according to one embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a control system in a power transmission device according to one embodiment of the present invention.

FIG. 5 is a flowchart showing a method of operating a power transmission device according to one embodiment of the present invention.

FIG. 6 is a flowchart showing a method of operating the power transmission device according to one embodiment of the present invention.

FIG. 7 is a diagram showing torque fluctuation of a power transmission device according to one embodiment of the present invention.

FIG. 8 is a flowchart showing a method of operating a power transmission device according to another embodiment of the present invention.

FIG. 9 is a flowchart showing a method of operating a power transmission device according to another embodiment of the present invention.

FIG. 10 is a diagram showing torque fluctuations of a power transmission device according to another embodiment of the present invention.

FIG. 11 A is a schematic diagram showing a pinion and a gear member in one embodiment of the present invention.

F1G. 11B is a schematic diagram showing a pinion and a gear member in one embodiment of the present invention.

DETAILED DESCRIPTION

[0036] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It is intended, however, that unless particularly specified, dimensions, materials, shapes, relative positions and the like of components described in the embodiments shall be interpreted as illustrative only and not limitative of the scope of the present invention.

[0037] First, the structure of a power transmission device according to at least one embodiment of the present invention will be described with reference to FIG. 1 to FIG. 4. The power transmission device 10 may be a constituent device of a wind power plant (hereinafter, referred to as a wind turbine 1 ) and can be applied to a wind turbine 1 installed onshore or offshore.

[0038] As illustrated non-limitingly in FIG. 1, a wind turbine 1 according to at least one embodiment of the present disclosure includes a plurality of wind turbine blades 2 (three in an example shown in FIG. 1), a hub 3 to which the wind turbine blade 2 is attached, a wind turbine rotor 4 including a main shaft 5 connected to the hub 3, a nacelle 7 rotatably supporting the wind turbine rotor 4 via a main bearing (not shown), a tower 8 supporting the nacelle 7 so as to be horizontally rotatable, and a base 9 provided with the tower 8. The wind turbine 1 is configured so that a power generator 6 receives rotational force of the wind turbine rotor 4 transmitted via a drive train 5 A including the main shaft 5, and generates electric power.

[0039] In some embodiments, the drive train 5 A may be provided with a gear type speed increasing gear for increasing the rotation of the main shaft 5, or a hydraulic transmission may be used instead of the gear type speed increasing gear. In another embodiment, instead of the drive train 5A, a direct drive system in which the main shaft 5 and the generator 6 are directly connected may be adopted.

[0040] As illustrated non-limitingly in FIGS. 1 to 4, a power transmission device 10 according to at least one embodiment of the present disclosure includes a plurality of driving machines 20 each of which has a pinion gear 24, a gear member 40 which includes a damaged portion 43 and engages with the plurality of pinion gears 24, and a controller 60 which individually controls the plurality of driving machines 20.

[0041] The driving machine 20 may be, for example, a yaw drive 20A for adjusting yaw angle of the wind turbine 1 in the yaw rotation mechanism (also referred to as a yaw system) of the wind turbine 1.

[0042] One or a plurality of (for example, 4 to 10) driving machines 20 may be arranged for one wind turbine 1. In the example shown non-limitingly in FIGS. 2 to 4, six driving machines 20 are arranged in one wind turbine 1. Each of the driving machines 20 may be configured to be rotatable relative to the base portion 18 (nacelle base or base frame 18 A) via a hollow cylindrical bracket 26, for example. That is, the base portion 18 may include a bracket 26 that supports the driving machine 20 in a relatively rotatable manner with respect to the base portion 18. The bracket 26 is fixed to the base portion 18 on the side of one end (for example, an upper end portion) in the axial direction of the cylinder, and may be configured to rotatably support the casing 25 of the driving machine 20 in the flange provided on the other end portion (for example, a lower end portion). The flange may be, for example, an annular or arcuate inner flange.

[0043] The driving machine 20 may include a yaw motor 21 , a reduction gear 22 disposed between the yaw motor 21 and a ring gear 40 A (gear member 40) for yaw rotation, a pinion gear 24 disposed between the reduction gear 22 and the ring gear 40A and connected to a drive shaft 23 which is an output shaft of the reduction gear 22, and a casing 25 accommodating at least the reduction gear 22. That is, the driving machine 20 can be configured such that, for example, an external force such as wind load acts via the ring gear 40A in the order of the pinion gear 24, the drive shaft 23, the reduction gear 22, and the yaw motor 21. [0044] The yaw motor 21 may be electrically and/or electronically connected to the controller 60 and/or the power terminal of the wind turbine 1 and may be rotationally driven in response to control signals and/or power transmitted from the controller 60 (see FIG. 4).

[0045] The reduction gear 22 may include a multi-stage (a plurality of stages) or stepless speed change mechanism and may include, for example, four to five or more gear mechanisms (for example, planetary gears or the like).

[0046] For example, as illustrated non-limitingly in F1G. 2, the driving machine 20 may include a rotor 14 and a casing 25 that houses the rotor 14 and is supported by the base portion 18 so as to form the stator 16 of the driving machine 20.

[0047] The rotor 14 is configured to be rotatable relative to the stator 16, and is driven with being directly or indirectly supported by the stator 16. The rotor 14 can mainly be configured as a part contributing to power transmission for driving the wind turbine 1 or changing a posture of the wind turbine 1 by rotation. In the present disclosure, the rotor 14 that can be applied to various parts of the wind turbine 1 may also be collectively referred to as a rotating system.

[0048] The rotor 14 of the driving machine 20 may include, for example, an inner rotor including the output shaft of the yaw motor 21 itself, a reduction gear 22 connected to the output shaft of the yaw motor 21, a drive shaft 23 as an output shaft of the yaw drive 20A connected to the reduction gear 22, and a pinion gear 24 connected to the drive shaft 23 and meshed with the ring gear 40A.

[0049] The stator 16 may mainly include a body of the wind turbine 1 as a structure and a portion fixed to the wind turbine 1 to support other constituent elements. In the present disclosure, the stator 16 that can be applied to various parts of the wind turbine 1 may also be collectively referred to as a fixed system in some cases.

[0050] The casing 25 may include a step or flange on the outer surface thereof, and may be configured so that at least a part thereof faces the base portion 18. At least a part of the casing 25 may be configured such that relative rotation with respect to the base portion 18 is permitted when a rotational force equal to or greater than the threshold torque is applied to the rotor 14, and may be configured to be rotatable together with the rotor 14. In this way, the casing 25 may constitute the stator 16 by being supported by the base portion 18. The threshold torque in this case may be set in consideration of preventing damage to elements to be protected due to low mechanical strength among, for example, the components of the driving machine 20 or the mechanical elements that directly or indirectly transmit power to the driving machine 20. The threshold torque when the yaw drive 20A is applied as the driving machine 20 may be set to a value that can prevent damage to the ring gear 40A, for example.

[0051] The driving machine 20 may be disposed below the ring gear 40A. In this case, the reduction gear 22 may be disposed above the yaw motor 21, and the pinion gear 24 may be disposed above the reduction gear 22 (See FIGS. 1 and 2). Further, the driving machine 20 may be disposed above the ring gear 40A. In this case, the reduction gear 22 may be disposed below the yaw motor 21, and the pinion gear 24 may be disposed below the reduction gear 22.

[0052] The gear member 40 may include a ring gear or a rack. The ring gear as the gear member 40 may include the above-described ring gear 40A in the yaw rotation mechanism of the wind turbine 1 (see FIGS. 2 and 3). In another embodiment, the gear member 40 may include a rack 40B (see, for example, FIGS. 11 A and 11B).

[0053] The nacelle 7 described above may be supported by the tower 8 via a nacelle base plate (not shown) and a yaw rotation bearing (not shown) which form the bottom surface of the nacelle 7. In the nacelle base plate (or the upper part of the tower 8), the above-mentioned driving machine 20 including, for example, the yaw motor 21 (see FIGS. 2 and 4) and the pinion gear 24 may be fixed. The nacelle 7 may be configured to be tumable (that is, yaw angle thereof can be adjusted) with respect to the tower 8 by driving the driving machine 20 with the pinion gear 24 meshed with the ring gear 40A provided on the tower 8 side (or nacelle side). Further, each wind turbine blade 2 is supported by the hub 3 via a blade turning bearing (not shown), and by the rotation of the pitch drive actuator 73 (see FIG. 4) provided in the hub 3, the pitch angle of the wind turbine blade 2 may be configured to be adjustable (e.g. to any angle between full fain to full feather). [0054] In the wind turbine 1 of the above exemplary configuration, a state value indicating a damaged state or a deteriorated state of various components may be acquired by a state value detection sensor (for example, including a load sensor 77 shown in FIG. 4) and may be reported to the controller 60. Specific examples of the state values of the various components in each wind turbine 1 include, for example, weight of the wind turbine blades 2, weight unbalance between the wind turbine blades 2, and vibration of the wind turbine blade 2 and the like. In addition, fatigue loads on the base of the tower 8 or the upper part of the tower 8 and vibrations of the tower 8 can be cited as examples indicating damaged state or deteriorated state of the tower 8. Further, as a representative of damaged state or deteriorated state of the drive train 5 A such as a speed increasing gear or a hydraulic transmission, vibration of the main bearing (not shown) or a bearing of the hydraulic pump, vibration or swinging of the main shaft 5, piston vibration or an amplitude of the hydraulic pump, the efficiency of the hydraulic transmission, and the like may be cited. In addition, fatigue due to stress concentration can be cited as one indicative of a damaged state or deteriorated state of a member made of a casting such as a nacelle base plate or a hub 3.

[0055] The controller 60 according to at least one embodiment of the present disclosure is configured to set the torque generated by the driving machine 20 of a first state to a low level, which is lower than in the case of a second state. The first state may be defined as a state in which the driving machine 20 is disposed so as to be able to engage with a predetermined region 44 including the damaged portion 43 of the gear member 40. The second state may be defined as a state in which the driving machine 20 engages with the gear member 40 at an area other than the predetermined region 44.

[0056] Here, the controller 60 in at least one embodiment of the present disclosure will be described in detail.

The controller 60 controls the operation of each drive unit in the wind turbine 1. The controller 60, non-limitingly shown in FIG. 4, may be a computer, for example, and includes a CPU 61, a ROM (Read Only Memory) 63 as a storage unit for storing data such as various programs and tables executed by the CPU 61, a RAM (Random Access Memory) 62 which functions as an expansion area or a calculation area when each program is executed. In addition to the above, the controller 60 may include a hard disk drive (HDD) as a mass storage device (not shown), a communication interface for connecting to a communication network, and an access unit to which an external storage device is attached. In some embodiments, the controller 60 may include, for example, a database 68 that stores optimal control settings associated with the wind condition parameters. Various tables such as the power generation output distribution table 69 and the like may be stored in the database 68, for example. All of these are connected via a bus 64. Further, the controller 60 may be connected to a display unit (not shown) or the like composed of an input unit (not shown) including a keyboard, a mouse, and the like and a liquid crystal display device displaying data and the like.

[0057] In some embodiments, detection signals related to wind direction, wind speed, and load may be transmitted to the controller 60 from the wind direction sensor 75, the wind speed sensor 76, and the load sensor 77 provided in each wind turbine 1, respectively. One or more of the above load sensors 77 may be installed in places where loads by equipment or wind act, such as main bearings (not shown), gear members 40, towers 8, and the like. In some embodiments, the controller 60 may be connected to the yaw motor 21 of the driving machine 20, the yaw brake drive actuator 72, the pitch drive actuator 73 and the pitch brake drive actuator 74 via a bus 64 (and a signal line not shown).

[0058] In some embodiments, the ROM 63 may store an output calculation program 65 for calculating the output of the wind turbine 1 and an output optimization program 66 for optimizing the output of the wind turbine 1. Further, the ROM 63 may store a damaged part protecting operation program 67 configured to set the torque generated by the driving machine 20 of the first state disposed so as to be able to engage with the predetermined region 44 including the damaged portion 43 of the gear member 40 to a low level, which is lower than in the case of the second state in which the driving machine 20 meshes with the gear member 40 at a region other than the predetermined region 44 (see FIGS. 4 to 7).

[0059] For example, as exemplified non-limitingly in FIG. 3, given that relative arrangement between a gear member 40 including a damaged portion 43 and a plurality of (for example, six in No. 1 to No. 6 in FIG. 3) driving machines 20 are changed according to the driving of each of the driving machines 20. At this time, for example, in a state where each of all the driving machines 20 mesh with the gear member 40 except for the predetermined area 44 including the damaged portion 43 (or extending across the damaged portion 43) (that is, when the driving machine 20 is in the second state), each of the driving machines 20 generates substantially the same level of torque, and the load transmitted to and from the gear member 40 is transmitted to each driving machine 20 so that all the driving machines 20 share the load substantially evenly (see the normal torque in FIGS. 7 and 10, for example).

The predetermined region 44 may extend over the same distance (or the same number of teeth) across the damaged portion 43 in the gear member 40 in a front-back direction of the relative movement with the pinion gear 24, for example. In the case where the ring gear 40A is applied as the gear member 40, for example, a range including the same degree of phase regions with respect to the clockwise direction and the counterclockwise direction across the damaged portion 43 may be set as the predetermined region 44. The distance, the number of teeth, or the phase in such a predetermined region 44 can be arbitrarily set according to the strength of the gear member 40 or the damage degree of the damaged portion 43. The gear member 40 may have more than one damaged portion 43, which portions may sit in the same predetermined region 44 or different predetermined regions 44.

Further, the position of the damaged portion 43 in the entire gear member 40 can be specified by, for example, the distance, the number of teeth, the phase, the coordinates, or the like from the reference position set in advance for the gear member 40. For example, the position of the damaged portion 43 in the ring gear 40A of the wind turbine 1 may be defined by the phase from a certain reference direction with reference to the tower 8 to the damaged portion 43, or may be defined by the phase from a certain reference direction with reference to the nacelle 7 to the damaged portion 43.

[0060] Processing realized by the CPU 61 reading out the damaged part protecting operation program 67 from the ROM 63 and developing the program in the RAM 62 and executing the processing may be carried out by setting at least the driving machine 20 disposed closest to the damaged portion 43 (driving machine 20 of No. 6 in FIG. 3) as a control object. Such processing may include, for example, low torque control when the driving machine 20 located closest to the damaged portion 43 is being engaged with the gear member 40 in the region 44. In some embodiments, if there are a plurality of driving machines 20 that mesh with the predetermined region 44, all of the driving machines 20 that mesh with the region 44 of the gear member 40 may be subject to the low torque control.

The torque to be generated by the driving machine 20 which is to be subjected to the low torque control may include static torque to be generated at the time of mechanical braking or motor braking (at the time of stop) as well as dynamic torque to be generated at the time of yaw rotation (at the time of driving).

Further, the relationship between the pinion gear 24 and the damaged portion 43 is not limited to the case where meshing is performed in a state in which torque transmission is possible. That is, for example, even when the damaged state of the damaged portion 43 is the total loss of the tooth 41 in the gear member 40 and the torque cannot be transmitted between the pinion gear 24 and the gear member 40, the embodiments of the present disclosure as described above or below can be applied as long as the pinion gear (or the driving machine 20) is disposed at a position opposite to the damaged portion 43.

[0061] With the above configuration, it is possible to reduce the stress acting on the damaged portion 43 of the gear member 40 from the pinion gear 24 of the driving machine 20 in the first state. Therefore, appropriate operation conditions can be determined in consideration of the damage of the power transmission portion. Thereby, it is possible to reduce the risk of damage expansion and consequential damage occurrence to the damaged portion 43. Therefore, it is possible to take appropriate service life extension measures on the damaged gear member 40 or the power transmission device 10.

[0062] In some embodiments, if there is at least one driving machine 20 in the first state, the controller 60 may set the torque to be generated by the driving machine 20 in the second state to a high level, which is higher than the torque generated by the driving machine 20 when all the driving machines 20 are in the second state.

That is, the controller 60 may be configured to set the torque to be generated by the driving machine 20 in the second state to a high level, which is higher than in the normal state (high level torque control), if there is at least one driver 20 in the first state. For example, in the example shown non-limitingly in F1G. 7 and FIG. 10, when one driving machine 20 (for example, the driving machine 20 of No. 6) is in the first state, the torque to be generated by each of the remaining driving machines 20 in the second state (for example, the driving machines of No. 1 to No. 5) may be set to be higher than the normal operation mode.

In this way, the torque reduction of the at least one of the driving machines 20 engaged with the predetermined region 44 (or the predetermined phase region in the case of the ring gear 40A) including the damaged portion 43 in the gear member 40 can be complemented by one or more driving machine(s) 20. As a result, the necessary torque to be applied to the gear member 40 can be applied by the whole of the plurality of driving machines 20. Therefore, it is possible to maintain the smooth operation of the power transmission device 10 (and therefore the wind turbine 1 ) while reducing the load acting on the damaged portion 43 of the gear member 40 and prolonging the service life of the power transmission device 10 without the need to replace the gear member 40 or by postponing replacement or service to a more advantageous point in time.

[0063] As illustrated non-limitingly in FIG. 7 or FIG. 10, in some embodiments, with respect to the upper limit of the torque of each of the driving machines 20, the controller 60 may be configured to set the torque to be generated by the driving machine 20 (No. 6) in the first state disposed opposite to at least the damaged portion 43 as a first threshold value Thl, which the damaged portion 43 of the gear member 40 can withstand, or less, and set the torque to be generated by the driving machine 20 (No. 1 to 5) in the second state to be greater than the first threshold value Thl and not more than the second threshold value Th2 applied to the second state.

In this way, the driving machine 20 positioned so as to be disposed opposite to the region 44 where at least the damaged portion 43 exists in the gear member 40 is controlled so as to generate a torque equal to or less than the first threshold value Thl which the damaged gear member 40 (e.g. ring gear 40A) can withstand without further or excessive damaging the gear member 40. Therefore, since it is possible to reduce the load on the damaged gear member 40 at least against the damaged portion 43 to protect the gear member 40, it is possible to take appropriate service life extension measures for the gear member 40 and thus for the power transmission device 10 for example so service, repair or replace can be prevented or postponed to a more suitable time.

[0064] In some embodiments, for example, as illustrated non-limitingly in FIG. 10, the controller 60 may be configured to drive the at least one driving machine 20 in the first state at a lower torque closer to the damaged portion 43.

That is, in addition to a control pattern in which the torque falls sharply / sharply increases stepwise between the case (namely, the state of the low level torque control) where the pinion gear 24 meshes with or is opposed to the damaged portion 43 of the gear member 40 (including not only the ring gear 40A but also a rack 40B (see FIGS. 11 A and 11B) and the case with no damage, the control of the controller 60 may include such pattern in which the driving machine 20 gradually (linearly or otherwise) decreases in torque until it is disposed to be opposite to the damaged portion 43 from the state in which it is disposed in the area 44 in the vicinity of the portion 43 (see FIG. 11 A, for example) or gradually (linearly or otherwise) increases as the driver 20 moves away from the damaged portion 43 (substantially trapezoidal shape, for example).

In this way, the driving machine 20 positioned opposite to the predetermined region 44 including the damaged portion 43 of the gear member 40 (for example, the ring gear 40A) is driven with lower torque as it is closer to the damaged portion 43. That is, as the relative distance between the damaged portion 43 of the gear member 40 and the driving machine 20 becomes closer, the driving machine 20 is driven with lower torque, and at the phase where the damaged portion 43 exists, it is driven with the lowest torque (including zero). Therefore, it is possible to appropriately reduce the load on the damaged portion 43 while suppressing the sudden torque change of the driving machine 20, so that appropriate life prolongation measures can be taken to the power transmission device 10 (for example, the yaw rotation system or a pitch drive system of the wind turbine 1) including the damaged gear member 40.

[0065] In some embodiments, the controller 60 may be configured to drive the plurality of driving machines 20 to mesh with the gear member 40, respectively, at zero relative speed.

That is, the number of revolutions (rotational speed) of the driving machine 20 may be controlled so that the teeth 41 of the gear member 40 and the pinion gear 24 do not slip or collide with each other and meshes with the same speed (or peripheral speed), when the pinion gear 24 of the driving machine 20 starts to mesh with the damaged portion 43 of the gear member 40. In some embodiments, for example, the rotation speed of the pinion gear 24 may be controlled to maintain constant speed and does not rise or fall abruptly, for example, compared to the other driving machines 20 (for example, No. 1 to No. 5), even in a situation in which a plurality of (two or more) adjacent teeth 41 of the gear member 40 receive damage (for example, a defect of the tooth 41 due to wear, cracking, etc.), and there exists a relatively big damaged portion 43 that may cause the pinion gear 24 to be accelerated, decelerated or slipped.

According to the above configuration, when the gear member 40 is partially damaged, the plurality of driving machines 20 are driven so as to mesh with the gear member 40 at a relative speed of zero. Thereby, for example, in the case where a part of the teeth 41 is totally damaged as a damaged form of the damaged portion 43, the driving machine 20 disposed to engage with the damaged portion 43 can be prevented from increasing its rotational speed due to idle rotation of the pinion gear 24. Therefore, it is possible to appropriately prevent occurrence of secondary damage to the next tooth 41 or the pinion gear 24 due to the difference in relative speed between the meshing teeth 41 and the pinion gear 24.

[0066] In some embodiments, the damaged portion 43 may be a tooth 41 of the gear member 40. The first threshold value Thl may be set according to the ratio of the tooth width 1 of the tooth 41 of the damaged portion 43 to the tooth width L of the tooth 41 other than the predetermined region 44.

That is, the first threshold value Thl can be set according to the ratio (= 1 / L) of the tooth width 1 of the tooth 41 in the damaged state to the tooth width L of the tooth 41 in the normal state (see FIG. 11B).

By setting the first threshold value Thl in this way, the torque transmitted between the pinion gear 24 and the gear member 40 can be set to be limited to a torque level that the remaining teeth 41 can withstand, depending on the damage degree of the damaged portion 43. Therefore, it is possible to share a part of the torque transmitted between the pinion gear 24 and the gear member 40 within a possible range to the remaining teeth 41 while suppressing an excessive load on the remaining teeth 41.

[0067] In some embodiment, the low level torque described above may be defined as a level at which the damaged portion 43 of the gear member 40 maintain a predetermined service life.

That is, in setting the first threshold value Thl, the torque level of the first threshold value Thl may be determined in consideration of the load (torque) applied to the damaged portion 43, its repetition number, and a known lifetime consumption rate curve, etc., depending on the degree of damage in the damaged portion 43, in order that the damage portion 43 can maintain a predetermined service life.

In this way, considering the operation plan, maintenance plan, etc. of the device (for example, the wind turbine 1) on which the power transmission device 10 is mounted, the operation of the device can be continued with the load (torque) applied to the damaged portion 43 from the pinion gear 24 of the driving machine 20 engaged with the damaged portion 43 is suppressed, while protecting the damaged portion 43 so that a predetermined service life can be maintained.

[0068] In some embodiments, the above-described high level of torque may be defined such that the total torque of all of the plurality of driving machines 20 is defined as the same torque as the total torque of all the plurality of driving machines 20 without the damaged portion 43.

That is, in the case where at least one of the driving machines 20 is in the first state, the torque (high level torque) to be generated by each of the remaining driving machines 20 in the second state is such that the sum of them and the torque generated by the driving machine 20 in the first state can be set to a torque level equal to the total torque of all the driving machines 20 in the normal case where the gear member 40 is not damaged.

With such a configuration, it is possible to substantially cancel the torque reduction caused by the driving machine 20 meshing with the predetermined area 44 (the predetermined phase area in the case of the ring gear 40A) including the damaged portion 43 in the gear member 40, that is the torque reduction can be compensated by other driving machines 20. Therefore, since the plural driving machines 20 can cooperatively undertake the necessary torque to be applied to the gear member 40 (or to be transmitted from the gear member 40), it is possible to effectively maintain smooth operation of the power transmission device 10 (and therefore the wind turbine 1) while reducing the load to be applied to the damaged portion 43 of the gear member 40, and prolonging the service life of the power transmission device 10.

Note that the sum (system torque) of the torques to be generated by each of the plurality (all) of the driving machines 20 is set so as to always be higher than the maximum value of the external force (or required torque) that can be predicted in the system (or so as to be balanced with the maximum value of the external force) (see FIG. 7 or FIG. 10).

[0069] In some embodiments, the total torque of all of the plurality of driving machines 20 may be defined as a level at which each of the second state driving machines 20 can maintain a predetermined service life.

That is, when setting the threshold value (for example, a third threshold value Th3 exemplified non-limitingly in FIG. 7 or FIG. 10) of the total torque by all of the plurality of driving machines 20, the torque level of the third threshold Th3 may be determined from the load (torque) transmitted between the pinion gear 24 and the gear member 40, its repetition number and the known lifetime consumption rate curve or the like, so that the teeth 41 in a healthy state can maintain a predetermined service life.

In this way, in consideration of the operation plan, maintenance plan, and the like of the device (for example, the wind turbine 1) on which the power transmission device 10 is mounted, it is possible to regulates the load (torque) applied to the gear member 40 from the pinion gear 24 of the driving machines 20 meshing with the normal-state teeth 41, to continue the operation of the power transmission device 10 so that a predetermined service life can be maintained.

[0070] In some embodiments, the power transmission device 10 may include a yaw system of a wind turbine in which a gear member 40 is operational between a nacelle 7 and a tower 8 that rotatably supports the nacelle 7, or a pitch system of a wind turbine blade 2.

That is, when the power transmission device 10 includes the yaw system of the wind turbine 1 , for example, by performing the low level torque control so as to protect the damage (damaged portion 43) in the ring gear 40A of the wind turbine 1 as described above, it is possible to reduce the risk of damage expansion and secondary damage occurrence in the damaged portion 43. Therefore, it is possible to take appropriate service life extension measures on the damaged ring gear 40A (the gear member 40) and the power transmission device 10.

Further, when the power transmission device 10 includes the pitch system of the wind turbine 1 , for example, when torque is exchanged between the blade root portion of the wind turbine blade 2 and the pinion gear 24 of the pitch drive actuator 73, it is possible to reduce the risk of damage expansion and secondary damage occurrence in the damaged portion 43, by performing the low-level torque control so as to protect the damaged portion 43 of the gear member 40. Therefore, it is possible to take appropriate service life extension measures on the damaged gear member 40 or the power transmission device 10.

[0071] As illustrated non-limitingly in FIG. 5, a method of operating the power transmission device 10 according to at least one embodiment of the present disclosure, is a method of operating the power transmission device 10 having a gear member 40, wherein when the gear member 40 is partially damaged, the torque generated by the first state of the driving machine 20 relatively arranged so as to be able to engage with the predetermined area 44 including the damaged portion 43 of the gear member 40 is set (step Sl) to a lower level than in the case of the second state in which the gear member 40 is engaged with the gear member 40 other than the region 44 of the second gear 44. In the above operation method, the driving machine 20 is operated according to the set torque level (step S2).

With this method, as described above, the stress acting on the damaged portion 43 of the gear member 40 from the pinion gear 24 of the driving machine 20 in the first state can be reduced. Therefore, it is possible to determine an appropriate operating condition in consideration of damage of the power transmission section. Since it is possible to reduce the risk of damage to the damaged portion 43 and occurrence of secondary damage, it is possible to take appropriate service life extension measures on the damaged gear member 40, and thus the power transmission device 10.

[0072] In some embodiments, as illustrated non-limitingly in FIG. 6, the operation method of the power transmission device 10 may include a step of detecting the damaged portion 43 of the gear member 40 (step Sl l), a step of measuring the damaged portion 43 (step S12), a step of evaluating the durability level of the torque in the damaged portion 43 (Step S13), and a step (steps S14 and S2) of performing an actual operation according to the evaluated durability level.

The detection of the damaged portion 43 (step Sl l) and the measurement of the damaged portion 43 (step S12) can be realized by the controller 10 which has received the measurement result from the operator or various sensors, for example. In addition, the evaluation of the torque durability level (step S13), the setting of the torque to be generated by the driving machine 20 (step S14), and the actual driving of the driving machine 20 (step S2) according to the set torque level can be realized by the operator or the controller 10 using the configuration described in any of the above embodiment.

In this way, in consideration of the operation plan, maintenance plan, and the like of the device (for example, the wind turbine 1) on which the power transmission device 10 is mounted, it is possible to continue the operation while protecting the damaged portion 43 so that the load (torque) applied to the damaged portion 43 from the pinion gear 24 of the driving machine 20 that can engage with the damaged portion 43 can be suppressed and the predetermined service life can be maintained or - if needed - service of the damaged part (repair or replacement) can be performed when timing is more advantageous without having to stop energy production until service can be performed. Allowing for flexible planning of service is particularly advantageous for offshore wind turbines where service is very costly as it typically requires vessel or helicopter for access.

[0073] In some embodiments, the above method may include, for example, as illustrated non-limitingly in FIG. 8, evaluating the remaining capacity (for example regarding fatigue or wear) or remaining life of the gear member 40 (step S21), and determining an allowable torque level based on the evaluated remaining capacity or remaining life (step S22).

For example, by measuring the height or the thickness of the tooth 41 of the damaged portion 43 in the gear member 40 to obtain a residual height (residual thickness) compared with the normal state (evaluation of remaining capacity), the life expectancy of the gear member 40 can be evaluated based on the above values of the gear member 40, the material of the gear member 40, the assumed load (torque), the number of repetitions thereof, and the known lifetime consumption rate curve. Also, based on the estimated remaining capacity or the remaining life, the level of torque that the gear member 40 can tolerate can be determined.

According to the above method, the load (torque) exchanged between the pinion gear 24 of the driving machine 20 and the gear member 40 is regulated within an appropriate torque level, and the operation of the power transmission device 10 can be continued so that a predetermined service life can be maintained.

[0074] In some embodiments, for example, as illustrated non-limitingly in FIG. 9, the above method may include, a step (step S31) of evaluating the remaining capacity (for example regarding fatigue or wear) or the remaining life of the gear member 40, and a step (step S32) of determining the number of cycles to be applied to the damaged region 44 by considering the relation between the total storage capacity and the external torque which the system should support.

That is, by measuring the height or thickness of the tooth 41 of the damaged portion 43 of the gear member 40, residual height (residual thickness) can be obtained (evaluation of remaining capacity), and the remaining life of the gear member 40 can be evaluated on the basis of these obtained values, the material of the gear member 40, the load (torque) assumed to be applied, its repetition number, and a known lifetime consumption rate curve and the like. Also, on the basis of the evaluated remaining capacity or remaining life, number of repetitions (number of cycles) of the load that the gear member 40 can tolerate can be determined.

According to the above method, the number of cycles of the load (torque) that may be repeatedly transmitted between the pinion gear 24 of the driving machine 20 and the gear member 40 can be regulated within an appropriate number of times, and the operation of the power transmission device 10 can be continued so that a predetermined service life can be maintained.

[0075] According to at least one embodiment of the present disclosure described above, it is possible to determine an appropriate operating condition in consideration of the damaged portion 43 of the power transmission device 10.

[0076] One aspect of the invention concerns the use of a power transmission device 10 according to an earlier described embodiment of the invention for postponing for a period of time, T, service of the partially damaged gear member 40. A similar aspect of the invention concerns the use of a method for operating a power transmission device 10 according to an earlier described embodiment of the invention for postponing for a period of time, T, service of the partially damaged gear member 40. Here, service refers to repair or replacement of a part.

For both these aspects of the invention, it was found to be particularly advantageous that the embodiments of the invention allowed the gear member 40 to remain operable during the period of time, T, so for example energy production of a wind turbine may be continued even though an important part of the wind turbine such as the yaw system is damaged. Being able to continue operation is particularly advantageous for offshore wind turbines as service may take considerable time to plan and may only be possible to perform at certain (weather) conditions.

Furthermore, the production of a wind turbine varies dependent on weather conditions, so being able to postpone service to a time where production is low or zero due to weather conditions is environmentally advantageous as it allows for maximum production of renewable energy and hence reduce the need for non-renewable energy. Furthermore, this also has major financial advantages for the wind turbine owner.

Industrial Applicability

[0077] At least one embodiment of the present invention can be used to determine appropriate operating conditions in consideration of damage of a power transmission device in the field of industry using the power transmission device and its operating method.

Claims

1. A power transmission device, comprising:

a plurality of driving machines each of which has a pinion gear;

a controller which individually controls the plurality of driving machines,

wherein the driving machine is defined as being in a first state when disposed to be able to engage with the gear member in a predetermined region including the damaged portion, and is defined as being in a second state when disposed to engage with the gear member in a region other than the predetermined region, and

2. The power transmission device according to claim 1 ,

wherein the controller is configured to set, if at least one driving machine is in the first state, the torque generated by the driving machine of the second state to a high level, which is higher than the torque generated when all the driving machines are in the second state.

3. The power transmission device according to claim 1 or 2,

wherein, regarding the upper limit of the torque of each of the driving machines, the controller is configured to

4. The power transmission device according to any one of claims 1 to 3,

wherein the controller is configured to drive the at least one driving machine of the first state with lower torque as the driving machine is closer to the damaged portion.

5. The power transmission device according to any one of claims 1 to 4,

wherein the controller is configured to drive each of the plurality of driving machines to engage with the gear member at a relative speed of zero.

6. The power transmission device according to any one of claims 1 to 5,

wherein the damaged portion includes a tooth of the gear member, and

the first threshold value is set according to a ratio of a tooth width of the tooth of the damaged portion to a tooth width of the tooth in the region other than the predetermined region.

7. The power transmission device according to any one of claims 1 to 6,

wherein the low level of torque is defined as a level at which the damaged portion of the gear member is able to maintain a predetermined service life.

8. The power transmission device according to any one of claims 2 to 7,

wherein the high-level torque is defined as a torque which makes the total torque of all of the plurality of driving machines to be the same level as the total torque of all of the plurality of driving machines in the absence of the damaged portion.

9. The power transmission device according to claim 8,

wherein the total torque of all of the plurality of driving machines is defined as a level at which each of the driving machines in the second state is able to maintain a predetermined endurance life.

10. The power transmission device according to any one of claims 1 to 9,

wherein the power transmission device includes a yaw system of a wind turbine operational between a nacelle and a tower rotatably supporting the nacelle, or a pitch system of a wind turbine blade.

11. A method of operating a power transmission device which includes a gear member, the method comprising:

setting, if the gear member is partially damaged, torque generated by a driving machine in a first state at which the driving machine is disposed to be able to engage with a predetermined region including a damaged portion to be a low level, which is lower than a torque of the driving machine in a second state at which the driving machine is disposed to engage with the gear member in a region other than the predetermined region.

12. The method of operating a power transmission device according to claim 11, further comprising:

detecting the damaged portion of the gear member;

measuring the damaged portion;

evaluating a durability level of torque at the damaged part; and

performing an actual operation according to the evaluated durability level.

13. The method of operating a power transmission device according to claim 11 or 12, further comprising:

evaluating remaining capacity or remaining life of the gear member; and

determining an allowable torque level based on the evaluated remaining capacity or the remaining life.

14. The method of operating a power transmission device according to any one of claims 11 to 13, further comprising:

evaluating remaining capacity or remaining life of the gear member; and

15. Use of the power transmission device according to any one of the claims 1 to 10 or the method according to any one of the claims 11 to 14 for postponing for a period of time, T, service of the partially damaged gear member, wherein the gear member remains operable during the period of time, T.