Wind turbine systems with external power supplies and methods

Abstract

To provide wind turbine systems with external power supplies and methods.SOLUTION: The present disclosure relates to wind turbine systems comprising: a main power supply line for supplying power to wind turbine components; an internal back-up power supply; and a first converter configured to convert power from the internal back-up power supply and supply power to the main power supply line. The wind turbine systems further comprise: an external power supply configured to supply power to the main power supply line; and an external power supply switch arranged between the external power supply and the main power supply line. The external power supply is further configured to supply power to the internal back-up power supply. The present disclosure also relates to methods for supplying power to the main power supply line of a wind turbine system.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to wind turbine systems including backup power sources, and more particularly to wind turbine systems including external power sources. The present disclosure also relates to methods of providing power to wind turbine components. [Background technology]

[0002] Modern wind turbines are commonly used to provide electricity to the power grid. This type of wind turbine typically includes a tower and a rotor located on the tower. The rotor usually consists of a hub and a number of blades, which rotate under the influence of the wind on the blades. This rotation generates a torque, which is usually transferred via the rotor shaft to a generator, either directly ("direct drive" or "gearless") or using a gearbox. The generator then generates electricity, which can be provided to the power grid.

[0003] The wind turbine hub may be rotatably coupled to the front of the nacelle. The wind turbine hub is coupled to a rotor shaft, which is rotatably mounted to the nacelle using one or more rotor shaft bearings located in a frame within the nacelle. The nacelle is a housing located on top of the wind turbine tower that may house and protect the gearbox and generator (if not located outside the nacelle) and, depending on the wind turbine, other components such as power converters and auxiliary systems.

[0004] Wind turbines typically include auxiliary systems that require power to operate, such as pitch control systems, ventilation and temperature regulation systems, communication systems, oil pumping systems, etc. Power to run these systems can typically be obtained from the utility grid.

[0005] If a grid loss occurs, i.e. if the wind turbine is for some reason unable to obtain and provide power to the grid, parts of the wind turbine's electrical system may not operate. To allow extended operation of at least some auxiliary systems of the wind turbine when the grid is unavailable, it is known to provide one or more energy storage and / or energy supply devices. For example, it is known to use batteries or capacitors as an internal backup power source, and / or to use diesel generators or solar panels as an external power source.

[0006] Multiple power sources / storage devices and / or relatively large energy supply / storage devices may be required to operate critical auxiliary systems for extended periods of time.

[0007] Also, during commissioning of a wind turbine, particularly an offshore wind turbine, the power grid may not be available and one or more energy storage and / or energy supply devices may be used to act as a power source and power various auxiliary systems of the wind turbine involved with commissioning. In particular, the energy storage device used to provide back-up power to the yaw system of the wind turbine may be used for carrying out commissioning tasks, and the diesel generators may be used to supplement the back-up power or to power the auxiliary power systems as required.

[0008] To meet the demands of the auxiliary systems of the wind turbines, the diesel generators need to be large. Diesel generators used for wind turbines are typically over 100 kVA in size and are very difficult and expensive to transport and install, especially for offshore wind turbines.

[0009] The present disclosure provides methods and apparatus that at least partially overcome some of the aforementioned shortcomings. Summary of the Invention

[0010] In one aspect of the disclosure, a wind turbine system is provided. The wind turbine system includes a main power supply line for supplying power to wind turbine components, an internal backup power source, and a first converter configured to convert power from the internal backup power source to supply power to the main power supply line. The wind turbine system further includes an external power source configured to supply power to the main power supply line, and an external power switch disposed between the external power source and the main power supply line. The external power source is further configured to supply power to the internal backup power source.

[0011] According to this aspect, the internal backup power supply is used to meet the power demand from the main power supply line, and the external power supply can be used simultaneously to charge the internal backup power supply, allowing for optimization of the available energy. The nominal storage capacity of the internal backup power supply can potentially be reduced, as it can be replenished as needed. Also, commissioning operations requiring power can be scheduled without interruption, thus reducing the commissioning time of the wind turbine or wind farm. The external power supply can also be made smaller, thus reducing costs. Small renewable power sources, such as solar panels, can also be used instead of diesel generators.

[0012] Throughout this disclosure, an internal backup power source may refer to a system or apparatus provided on a wind turbine and configured to at least partially store electrical energy to power certain components of the wind turbine, for example, when the power grid is unavailable. A UPS incorporating batteries and capacitors may also be used. Terms such as auxiliary power sources, stored energy sources and energy storage devices / systems may be used interchangeably herein.

[0013] Throughout this disclosure, providing power to components of a wind turbine may be understood as providing power to auxiliary systems of the wind turbine that require power to operate.

[0014] In another aspect of the disclosure, a method of powering a component of a wind turbine is provided, the method including powering a main power supply line connected to the component of the wind turbine with an internal backup power source and simultaneously charging the internal backup power source with an external power source.

[0015] In a further aspect, a backup power system for a wind turbine is provided, the backup power system including an internal backup power supply disposed on the wind turbine and an external power supply configured to charge the internal backup power supply while the internal backup power supply provides power to the wind turbine to power components of the wind turbine.

[0016] Additional objects, advantages and features of the embodiments of the present disclosure will become apparent to those skilled in the art upon examination of the specification or may be learned by practice. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic perspective view of an example wind turbine. [Diagram 2] 1 shows an example of a wind turbine hub and nacelle. [Diagram 3] 1 illustrates a schematic diagram of an example wind turbine system according to the present disclosure. [Figure 4] 1 is a flow chart illustrating an example of a method for supplying power to a main power supply line of a wind turbine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Reference will now be made in detail to the embodiments of the present disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of illustration and not by way of limitation. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the teachings. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield still further embodiments. Thus, the present disclosure is intended to cover such modifications and variations as come within the scope of the appended claims and their equivalents.

[0019] FIG. 1 is a perspective view of an example of a wind turbine 10. In this example, the wind turbine 10 is a horizontal axis wind turbine. Alternatively, the wind turbine 10 may be a vertical axis wind turbine. In this example, the wind turbine 10 includes a tower 15 extending from a support system 14 on a ground 12, a nacelle 16 attached to the tower 15, and a rotor 18 coupled to the nacelle 16. The rotor 18 includes a rotatable hub 20 and at least one rotor blade 22 coupled to the hub 20 and extending outwardly from the hub 20. In this example, the rotor 18 has three rotor blades 22. In alternative embodiments, the rotor 18 includes more or less than three rotor blades 22. The tower 15 may be fabricated from tubular steel to define a cavity (not shown in FIG. 1) between the support system 14 and the nacelle 16. In alternative embodiments, the tower 15 may be any suitable type of tower having any suitable height. According to an alternative, the tower may be a hybrid tower including a concrete portion and a steel tubular portion. It may also be a partial or complete lattice tower.

[0020] The rotor blades 22 are spaced relative to the hub 20 to rotate the rotor 18 and convert kinetic energy from the wind into usable mechanical energy, and therefore electrical energy. The rotor blades 22 are mated to the hub 20 by coupling blade root portions 24 to the hub 20 at a number of load transfer regions 26. The load transfer regions 26 may include hub load transfer regions and blade load transfer regions (both not shown in FIG. 1 ). Loads induced on the rotor blades 22 are transferred to the hub 20 through the load transfer regions 26.

[0021] In some examples, the rotor blades 22 may have a length ranging from about 15 m (meters) to about 90 m or more. The rotor blades 22 may have any suitable length that enables the wind turbine 10 to function as described herein. For example, non-limiting examples of blade lengths include lengths of 20 m or less, 37 m, 48.7 m, 50.2 m, 52.2 m, or more than 91 m. When wind strikes the rotor blades 22 from a wind direction 28, the rotor 18 rotates about the rotor axis 30. As the rotor blades 22 rotate and experience centrifugal forces, the rotor blades 22 also experience various forces and moments. As such, the rotor blades 22 may deflect and / or rotate from a neutral, i.e., unbiased, position to a biased position.

[0022] Additionally, the pitch angle of the rotor blades 22, i.e., the angle determining the orientation of the rotor blades 22 relative to the wind direction, can be varied by the pitch system 32 to control the load and power generated by the wind turbine 10 by adjusting the angular position of at least one rotor blade 22 relative to the wind vector. A pitch axis 34 of the rotor blades 22 is shown. During operation of the wind turbine 10, the pitch system 32 can, among other things, vary the pitch angle of the rotor blades 22 to reduce the angle of attack of (some of) the rotor blades, thereby facilitating a reduction in rotational speed and / or facilitating a stall of the rotor 18.

[0023] In this embodiment, the blade pitch of each rotor blade 22 is individually controlled by the wind turbine controller 36 or the pitch control system 80. Alternatively, the blade pitch of all rotor blades 22 may be simultaneously controlled by these control systems.

[0024] Further, in this example, as wind direction 28 changes, nacelle 16 may be rotated about yaw axis 38 to position rotor blades 22 relative to wind direction 28 .

[0025] In this example, the wind turbine controller 36 is shown as centralized in the nacelle 16, however, the wind turbine controller 36 may be a distributed system located throughout the wind turbine 10, on the support system 14, in the wind farm, and / or in a remote control center. The wind turbine controller 36 includes a processor 40 configured to perform the methods and / or steps described herein. In addition, many of the other components described herein include a processor.

[0026] As used herein, the term "processor" is not limited to integrated circuits referred to in the art as computers, but refers broadly to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application specific, integrated circuits, and other programmable circuits, and these terms are used interchangeably herein. It should be understood that a processor and / or control system may also include memory, input channels, and / or output channels.

[0027] FIG. 2 is an enlarged cross-sectional view of a portion of the wind turbine 10. In this example, the wind turbine 10 includes a nacelle 16 and a rotor 18 rotatably coupled to the nacelle 16. More specifically, a hub 20 of the rotor 18 is rotatably coupled to a generator 42 disposed within the nacelle 16 by a main shaft 44, a gearbox 46, a high-speed shaft 48, and a coupling 50. In the example, the main shaft 44 is disposed at least partially coaxially with a longitudinal axis (not shown) of the nacelle 16. Rotation of the main shaft 44 drives a gearbox 46, which drives the high-speed shaft 48 by converting the relatively slow rotational motion of the rotor 18 and main shaft 44 into a relatively fast rotational motion of the high-speed shaft 48. The latter is connected, with the aid of the coupling 50, to a generator 42 for generating electrical energy. Additionally, a transformer 90 and / or appropriate electronics, switches, and / or inverters may be disposed within the nacelle 16 to convert the electrical energy generated by the generator 42 having a voltage between 400V and 1000V into electrical energy having a moderate voltage, for example, between 10 and 35 KV. This electrical energy is conducted from the nacelle 16 to the tower 15 via a power cable.

[0028] The gearbox 46, the generator 42 and the transformer 90 may be supported by a main support structural frame of the nacelle 16, optionally embodied as a main frame 52. The gearbox 46 may include a gearbox housing coupled to the main frame 52 by one or more torque arms 103. In an embodiment, the nacelle 16 also includes a main forward support bearing 60 and a main aft support bearing 62. Additionally, the generator 42 may be mounted to the main frame 52 by a decoupling support means 54, particularly to prevent vibrations of the generator 42 from being introduced into the main frame 52 and thereby causing a source of noise emissions.

[0029] Optionally, main frame 52 is configured to carry the weight of rotor 18 and nacelle 16 components, as well as the overall loads caused by wind and rotational loads, and to introduce these loads into tower 15 of wind turbine 10. The rotor shaft 44, generator 42, gearbox 46, high speed shaft 48, coupling 50, and main frame 52, and any associated fastening, supporting, and / or fastening devices, including, but not limited to, forward support bearing 60 and aft support bearing 62, may be referred to as a drive train 64.

[0030] In some embodiments, the wind turbine may be a direct drive wind turbine without a gearbox 46. The generator 42 operates at the same rotational speed as the rotor 18 of the direct drive wind turbine and therefore typically has a much larger diameter than the generator used in a wind turbine with a gearbox 46 to provide the same amount of power as a wind turbine with a gearbox.

[0031] The nacelle 16 may also include a yaw drive mechanism 56 that is used to rotate the nacelle 16, and thereby the rotor 18, about the yaw axis 38 to control the approach or approach of the rotor blades 22 relative to the wind direction 28.

[0032] To properly position the nacelle 16 relative to the wind direction 28, the nacelle 16 may also include at least one meteorological measurement system 58 including a wind vane and anemometer. The meteorological measurement system 58 may provide information including the wind direction 28 and / or wind speed to the wind turbine controller 36. In this embodiment, the pitch system 32 is at least partially disposed within the hub 20 as a pitch assembly 66. The pitch assembly 66 includes one or more pitch drive systems 68 and at least one sensor 70. Each pitch drive system 68 is coupled to a respective rotor blade 22 (shown in FIG. 1 ) for modulating the pitch angle of the rotor blade 22 along the pitch axis 34. Only one of the three pitch drive systems 68 is shown in FIG. 2 .

[0033] In this embodiment, the pitch assembly 66 includes at least one pitch bearing 72 coupled to the hub 20 and each rotor blade 22 (shown in FIG. 1 ) to rotate each rotor blade 22 about the pitch axis 34. The pitch drive system 68 includes a pitch drive motor 74, a pitch drive gearbox 76, and a pitch drive pinion 78. The pitch drive motor 74 is coupled to the pitch drive gearbox 76 such that the pitch drive motor 74 provides a mechanical force to the pitch drive gearbox 76. The pitch drive gearbox 76 is coupled to the pitch drive pinion 78 such that the pitch drive pinion 78 is rotated by the pitch drive gearbox 76. The pitch bearing 72 is coupled to the pitch drive pinion 78 such that rotation of the pitch drive pinion 78 causes rotation of the pitch bearing 72.

[0034] The pitch drive system 68 is coupled to the wind turbine controller 36 for adjusting the pitch angle of the rotor blades 22 in response to one or more signals from the wind turbine controller 36. In this example, the pitch drive motor 74 is any suitable motor driven by an electric power and / or hydraulic system that enables the pitch assembly 66 to function as described herein. Alternatively, the pitch assembly 66 may include any suitable structure, configuration, arrangement, and / or components, such as, but not limited to, hydraulic cylinders, springs, and / or servo mechanisms. In certain embodiments, the pitch drive motor 74 is driven by the rotational inertia of the hub 20 and / or energy extracted from a stored energy source (not shown) that provides power to components of the wind turbine 10.

[0035] The pitch assembly 66 may also include one or more pitch control systems 80 for controlling the pitch drive systems 68 in accordance with control signals from the wind turbine controller 36 in case of certain preferred conditions and / or upon overspeed of the rotor 18. In an example embodiment, the pitch assembly 66 includes at least one pitch control system 80 communicatively coupled to each pitch drive system 68 for controlling the pitch drive systems 68 independently from the wind turbine controller 36. In an example embodiment, the pitch control system 80 is coupled to the pitch drive systems 68 and to the sensors 70. During normal operation of the wind turbine 10, the wind turbine controller 36 may control the pitch drive systems 68 to adjust the pitch angle of the rotor blades 22.

[0036] According to one embodiment, a power generator 84, including, for example, batteries and electrical capacitors, is disposed at or within the hub 20 and is coupled to the sensors 70, pitch control system 80, and pitch drive system 68 to provide a source of electrical power to these components. In this example, the generator 84 provides a continuous source of electrical power to the pitch assembly 66 during operation of the wind turbine 10. In an alternative embodiment, the generator 84 provides power to the pitch assembly 66 only during a power loss event of the wind turbine 10. A power loss event may include a loss or dip in the electrical grid, a malfunction of the electrical system of the wind turbine 10, and / or a failure of the wind turbine controller 36. During a power loss event, the generator 84 operates to provide electrical power to the pitch assembly 66 such that the pitch assembly 66 can operate during the power loss event.

[0037] In this example, pitch drive system 68, sensor 70, pitch control system 80, cables, and generator 84 are each disposed within a cavity 86 defined by an inner surface 88 of hub 20. In alternative embodiments, the components may be positioned relative to an outer roof surface of hub 20 and coupled directly or indirectly to the outer roof surface.

[0038] 3 is a schematic representation of a wind turbine system according to one embodiment of the present disclosure, the wind turbine system includes a main power supply line 200 for supplying power to wind turbine components, an internal backup power source 110, and a first converter 130 configured to convert power from the internal backup power source 110 and supply power to the main power supply line 200.

[0039] The wind turbine system further includes an external power source 120 configured to supply power to a main power supply line 200, and an external power switch 135 disposed between the external power source 120 and the main power supply line 200. The external power source 120 is further configured to supply power to an internal backup power source 110.

[0040] In a wind turbine system, an internal backup power source can be charged while still providing power to the main power supply. The batteries and / or capacitors of the internal backup power source can be charged and replenished while they are in use, so the power available in the internal backup power source to perform a particular task or supply a particular component is not limited to the stored charge level at any given moment. The external power source can be used only until peak power is reached, and a reduced power capacity external power source can be used, allowing the external power source to be significantly smaller, saving cost and time.

[0041] The arrows in Fig. 3 represent the direction in which power is supplied. As shown diagrammatically in the example of Fig. 3, the wind turbine system can be arranged such that a main power supply line 200 receives power from an internal backup power source 110 and / or from an external power source 120. The main power supply line 200 can supply the received power to different auxiliary systems within the wind turbine (e.g., a control and communication system, a ventilation system, etc.).

[0042] Additionally, the external power source 120 is connected to the internal backup power source 110 so as to provide power to the internal backup power source 110 .

[0043] The internal backup power supply 110 may include one or more batteries and / or capacitors that may be charged or discharged depending on the requirements of the wind turbine's electrical system. In some examples, the internal backup power supply 110 may have a power capacity equal to or greater than the maximum consumption of the wind turbine's most important auxiliary systems. In some examples, the internal backup power supply 110 may have a nominal power of 50-180 KVA. In some examples, the internal backup power supply 110 may be configured to provide backup power to the wind turbine's yaw system.

[0044] The internal backup power source 110 may be located within the wind turbine or in any suitable location relative to the wind turbine 10. In some examples, one or more internal backup power sources may be located within the nacelle 16. In FIG. 2, an internal backup power source 110, also referred to as a generator 84, is shown for the pitch system 32 of the blades 22. It should be understood that in other examples, such an internal backup power source 110 may be located elsewhere, such as within the tower, at or near the base of the tower, within a transition piece, etc. It should also be understood that additional internal backup power sources 110 may be provided in the example of FIG. 2 or other examples. The internal backup power source 110 may also be located within a wind farm to power multiple wind turbines 10.

[0045] Additionally, the internal backup power supply 110 is connected to the main power supply line 200 via a first converter 130 configured to convert the power supply and provide power to the main power supply line 200 .

[0046] 3, the first converter 130 may include a rectifier stage and an inverter stage. At the rectifier stage, a power converter may convert direct current (DC) power from the internal backup power source 110 from one voltage level to another. At the inverter stage, another converter converts the direct current (DC) power to alternating current (AC) power at the appropriate voltage and frequency for supply to the main power supply line 200.

[0047] In some examples, the internal backup power supply 110 is charged by the main power supply line 200 or the external power supply 120 .

[0048] The wind turbine's generator 42 generates AC power whose frequency varies with changing wind conditions. During normal operation of the wind turbine, the AC power generated from the wind turbine's generator 42 may be used to charge the internal backup power supply 110, and power may be supplied to the internal backup power supply 110 from the wind turbine's main power supply line 200. Thus, the first converter 130 may also be configured to regulate the power output from the generator 42 to one suitable for the internal backup power supply 110, for example DC power having a constant fixed frequency.

[0049] The external power supply 120 can be located outside the wind turbine. The external power supply 120 may have a lower power than that provided by the main power supply. The external power supply is primarily used to maintain a positive energy balance of the internal backup power supply 110, and its nominal power does not have to be equal to or greater than the maximum power consumption of the critical electrical systems of the wind turbine, i.e. the electrical systems powered by the internal backup power supply.

[0050] Thus, the external power supply 120 can be constructed in a much smaller size than those used in the art. The miniaturized external power supply can result in significant cost savings since all steps regarding its transportation and installation can be performed without the use of expensive resources such as large cranes. In some examples, the external power supply has a power of 20-55 kWA. In some embodiments, the external power supply provides 12-15 amps (A) to the internal backup power supply 110.

[0051] In some examples, the external power source 120 may be an engine generator, particularly a diesel generator, hi other examples, the external power source 120 may be a renewable power source, such as one or more solar panels.

[0052] 3, an external power switch 135 is disposed between the external power source 120 and the main power supply line 200. This switch can regulate the connection between the main power supply line 200 and the external power source 120 to provide two alternative methods for directing power. In some embodiments, or at certain times, the external power switch 135 allows power to be provided from the external power source 120 to the main power supply line 200. In other embodiments, or at other times, the external power switch 135 can be disposed such that power generated from the external power source 120 is directed to the internal backup power source 110.

[0053] Thus, the power generated by the external power source 120 may be fed directly into the main power supply line 200 or may be used to charge the internal backup power source 110 .

[0054] The wind turbine system may include a second converter 125 that converts the power provided by the external power source to the internal backup power source. In some examples, the wind turbine system includes a unidirectional AC / DC converter module 125 that connects the external power source 120 and the internal backup power source 110 and converts AC power generated by the external power source 120 into DC power that can be used to charge the internal backup power source 110.

[0055] In some examples, the external power supply 120 may be configured to adapt the power provided to the internal backup power supply 110. The external power supply 120 may include a controller configured to detect the power that the internal backup power supply 110 is providing to the wind turbine main line 200 and adjust the amount of power generated by the external power supply 120. The amount of power provided to the internal backup power supply 110 may be adjusted so that the external power supply 120 does not generate more power than necessary.

[0056] 4 is a flow chart of a method for powering components of a wind turbine, the method including powering a main power supply line 200 connected to the components of the wind turbine with an internal backup power source at block 402 and simultaneously charging the internal backup power source with an external power source at block 404.

[0057] In some examples, the method may include receiving a power request from a main power supply line 200, supplying power to the main power supply line 200 using an internal backup power supply 110 to meet the power request, and charging the internal backup power supply 110 using an external power supply 120 while the internal backup power supply 110 is supplying power to the main power supply line 200.

[0058] In some examples, a power demand may be generated during commissioning of the wind turbine.

[0059] In another example, a power requirement may arise during a power grid loss when a wind turbine is disconnected from the power grid.

[0060] Throughout this disclosure, when reference is made to the fact that a wind turbine is (electrically) disconnected from the power grid, it can be understood that the wind turbine is prevented from supplying power to or from obtaining power from the power grid.

[0061] In some embodiments, the power supplied by the external power supply 120 may be the same as the power that is leaving the internal back-up power supply 110, such that the internal back-up power supply 110 remains fully charged after its use.

[0062] In another example, the power provided by the external power supply 120 to the internal backup power supply 110 may be tailored to the actual requirements of the internal backup power supply 110 .

[0063] The power provided by the external power supply 120 to the internal backup power supply 110 may be less than the power provided by the internal backup power supply 110 to the main power supply line 200. The external power supply 120 may be configured with a controller capable of determining the amount of power that the external power supply 120 needs to provide such that the power stored in the batteries and / or capacitors of the internal backup power supply 110 is not depleted before the demand for power coming from the main power supply line 200 is met. The external power supply 120 may be configured with a controller capable of determining the amount of power that the external power supply 120 needs to provide such that the power stored in the batteries and / or ultracapacitors of the internal backup power supply 110 is not depleted before the demand for power from the main power supply line 200 is met.

[0064] In these examples, the external power supply 120 may adapt by reducing the power provided to the internal backup power supply 110, for example from 15 A to 10 A, if the controller detects that the external power supply 120 is not producing the nominal amount of power yet can fully charge the internal backup power supply 110.

[0065] The method thus enables the internal backup power supply to optimize the energy available to it by using only the amount of power required to keep it charged, while at the same time allowing the internal backup power supply to supply power to the main power supply lines, for example during commissioning of the wind turbine or in the event of a grid loss.

[0066] The external power requirement is reduced because the peak power demands on the mains supply can be met by the internal backup power source alone, thus allowing the wind turbine system to use smaller and more easily managed external power sources.

[0067] In another embodiment, the method may include continuously charging the internal backup power supply 110 with the external power supply 120. The external power supply may be charged slowly, for example at 10A, until the internal backup power supply is fully charged.

[0068] Even if the external power supply 120 charges the internal backup power supply 110 while providing power to the main power supply line 200, the internal backup power supply 110 may not have reached its maximum power capacity after its use. In such a case, the external power supply 120 may continue to provide power to the internal backup power supply. Thus, in some examples, the method may include charging the internal backup power supply 110 with the external power supply 120 when the internal backup power supply 110 is not providing power to the main power supply line 200.

[0069] In some examples, the energy present in the internal backup power supply 110 may not be sufficient to cover the energy requirements of the main power supply lines 200. In that case, the external power supply 120 may be used to provide extra power to the main power supply lines 200. In these examples, the method may include receiving a power request from one main power supply line 200 and providing power to the main power supply line 200 with the external power supply 120 and the internal backup power supply 110 to meet the power request.

[0070] In other instances, the power generated by the external backup power source may be sufficient to meet the requirements of the main power supply 200 .

[0071] In a further example, the method may further include supplying power to the main power line 200 by the external power source 120 if the power requirements can be supplied by the external power source 120, and supplying power to the wind turbine by the internal backup power source 110 if the power requirements cannot be supplied by the external power source.

[0072] Power may be provided directly from the external power source 120 to the main power supply line 200, which may provide a more efficient power supply by avoiding unnecessary discharge of the internal backup power source 110.

[0073] In yet another aspect of the disclosure, a backup power system 100 for a wind turbine is provided. The system 100 comprises an internal backup power supply 110 disposed on the wind turbine and an external power supply 120. The external power supply is configured to charge the internal backup power supply 110 while the internal backup power supply 110 supplies power to a main power supply line 200 of the wind turbine for powering the wind turbine components.

[0074] In some embodiments, the power of the external power supply 120 may be lower than the power of the mains power supply. In some examples, the external power supply 120 may have a power of 20-55 kWA.

[0075] In some examples, the external power source 120 from an internal backup power system may be a diesel generator. In other examples, the external power source 120 may be a renewable power source. In some examples, the external power source 120 may include solar panels.

[0076] In some embodiments, the external power supply 120 may include a power converter 125 for adapting the power provided by the external power supply 120 to the internal backup power supply 110 .

[0077] Further aspects of the invention are provided by the subject matter of the following clauses. [Embodiment 1] 1. A wind turbine system comprising: a main power supply line (200) for supplying power to wind turbine components; an internal back-up power supply (110); a first converter (130) configured to convert power from the internal back-up power supply (110) and provide power to the main power supply line (200); an external power supply (120) configured to provide power to the main power supply line (200); an external power supply switch (135) arranged between the external power supply (120) and the main power supply line (200); The external power supply (120) is further configured to provide power to the internal back-up power supply (110). [Embodiment 2] 5. The wind turbine system of any of the previous embodiments, wherein the external power supply (120) is an engine generator, particularly a diesel generator. [Embodiment 3] 11. The wind turbine system of any preceding embodiment, wherein the external power supply (120) comprises a renewable power source, particularly one or more solar panels. [Embodiment 4] 2. The wind turbine system of claim 1, wherein the internal back-up power supply (110) comprises one or more batteries and / or ultracapacitors. [Embodiment 5] 5. The wind turbine system of any preceding embodiment, wherein the internal back-up power supply (110) is configured to provide back-up power to a yaw system of the wind turbine. [Embodiment 6] 13. The wind turbine system of any preceding embodiment, wherein a power of the external power supply (120) is lower than a power of the main power supply line, optionally wherein the external power supply has a power of 20 - 55 kWA. [Embodiment 7] 11. The wind turbine system of any preceding embodiment, further comprising a second converter (125) to convert the power supplied to the internal back-up power supply (110) by the external power supply (120). [Embodiment 8] A method (400) for providing power to a wind turbine component, comprising: supplying (402) power to a main power supply line (200) connected to the components of the wind turbine with an internal back-up power supply (110); and simultaneously charging (404) the internal back-up power supply (110) with an external power supply (120). [Embodiment 9] The method (400) of any preceding embodiment, wherein the external power supply (120) is a diesel generator with a power lower than a power of the main power supply line, optionally with a power of 20 - 55 kWA. [Embodiment 10] 13. The method (400) of any preceding embodiment, further comprising adapting the power supplied by the external power supply (120) to the internal back-up power supply (110) using a second converter. [Embodiment 11] 20. The method (400) of any preceding embodiment, further comprising the step of continuously charging the internal back-up power supply (110) with the external power supply (120), and charging the internal back-up power supply (110) with the external power supply (120) when the internal back-up power supply (110) is not supplying power to the main power supply line (200). [Embodiment 12] receiving a power demand from the main power supply line (200); supplying power to the main power supply line (200) with the internal back-up power supply (110) to meet the power demand; 20. The method (400) of any preceding embodiment, comprising: charging the internal back-up power supply (110) with the external power supply (120) while the internal back-up power supply (110) is supplying power to the main power supply line (200). [Embodiment 13] receiving a power demand from the main power supply line (200); 20. The method (400) of any preceding embodiment, comprising: supplying power to the main power supply line (200) with the external power supply (120) and with the internal back-up power supply (110) to meet the power demand. [Embodiment 14] 5. The method (400) of any preceding embodiment, wherein the power demand is produced during a grid loss event. [Embodiment 15]

[0023] The method (400) of any preceding embodiment, wherein the power demand is produced during commissioning of the wind turbine.

[0078] This specification uses examples to disclose the teachings, including preferred embodiments, and to enable any person skilled in the art to practice the teachings, including making and using any devices or systems, and performing any methods incorporated therein. The patentable scope is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be included in the claims if they have structural elements that do not differ from the language of the claims, or if they include equivalent structural elements that do not differ substantially from the language of the claims. Aspects from the various embodiments described, and other known equivalents to each such aspect, may be mixed and matched by those skilled in the art to construct additional embodiments and techniques according to the principles of this application. When reference signs related to the drawings are placed in parentheses in the claims, they are merely intended to improve the clarity of the claims, and should not be construed as limiting the scope of the claims. [Explanation of symbols]

[0079] 10 wind turbine 12: ground 14: support system 15: tower 16: nacelle 18: rotor 20: hub 22: rotor blade 24: blade root area 26: load transfer area 28: wind direction 30: rotor shaft 32: pitch system 34: pitch axis 36: wind turbine controller 38: yaw axis 40: processor 42: generator 44: main shaft 46: gearbox 48: high speed shaft 50: coupling 51: shaft sensor 52: main frame 53: generator sensor 54: decoupling support means 56: yaw drive mechanism 58: meteorological measurement system 60: main forward support bearing 62: main aft support bearing 64: drive train 66: pitch assembly 68: pitch drive system 70: sensor 72: pitch bearing 74: pitch drive motor 76: pitch drive gearbox 78: pitch drive pinion 80: Pitch control system 84: Power supply / generator 86: Cavity 88: Inner surface 90: Transformer 100: Backup power system 103: Torque arm 110: Internal backup power supply 120: External power supply 125: Second converter 130: First converter 135: External power switch 200: Main power supply line

Claims

1. 1. A wind turbine system comprising: a main power supply line (200) supplying power to the components of the wind turbine; An internal backup power supply (110); a first converter (130) configured to convert power from an internal backup power source (110) and supply power to a main power supply line (200); an external power source (120) configured to supply power to the main power supply line (200); an external power switch (135) disposed between the external power source (120) and the main power supply line (200); The wind turbine system, wherein the external power source (120) is further configured to supply power to the internal backup power source (110).

2. The wind turbine system according to claim 1, wherein the external power source (120) is an engine generator, in particular a diesel generator.

3. The wind turbine system of claim 1 , wherein the external power source (120) comprises a renewable power source, in particular one or more solar panels.

4. The wind turbine system of claim 1 , wherein the internal backup power source (110) comprises one or more batteries and / or one or more capacitors.

5. The wind turbine system of claim 1 , wherein the internal backup power supply (110) is configured to provide backup power to a yaw system of the wind turbine.

6. The wind turbine system of any preceding claim, wherein the power of the external power source (120) is lower than the power of the main power supply, and optionally the power of the external power source is between 20 and 55 kW A.

7. The wind turbine system of claim 1 , further comprising a second converter (125) that converts power provided by the external power source (120) to the internal backup power source (110).

8. A method (400) for supplying power to a wind turbine component, comprising: Providing (402) power to a main power supply line (200) connected to components of a wind turbine with an internal backup power source (110); and simultaneously charging (404) the internal backup power source (110) with the external power source (120).

9. The method (400) of any of claims 8 to 11, wherein the off-site power source (120) is a diesel generator having a power lower than that of the mains power supply, optionally having a power between 20 and 55 kW.

10. 10. The method (400) of claim 8, further comprising adapting the power provided from the external power source (120) to the internal backup power source (110) using a second converter.

11. 10. The method (400) of claim 8, further comprising the step of continuously charging the internal backup power source (110) with the external power source (120), and further comprising the step of charging the internal backup power source (110) with the external power source (120) when the internal backup power source (110) is not supplying power to the main power supply line (200).

12. receiving a power request from a main power supply line (200); providing power to a main power supply line (200) using an internal backup power source (110) to meet power requirements; charging the internal backup power source (110) with the external power source (120) while the internal backup power source (110) supplies power to the main power supply line (200).

13. receiving a power request from a main power supply line (200); 10. The method (400) of claim 8, further comprising: providing power to the main power supply (200) using an external power source (120) and an internal backup power source (110) to meet the power demand.

14. 14. The method (400) of claim 12 or 13, wherein the power demand is generated during a grid loss event.

15. The method (400) of claim 12 or 13, wherein the power request is generated during commissioning of the wind turbine.

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