Auxiliary power system and control for rural and / or off-grid wind turbines

Abstract

The invention relates to a wind turbine airport (100) comprising at least a first wind turbine (110) and a second wind turbine (120) for producing an electrical product, and a main line (101) connecting the first wind turbine (110) and the second wind turbine (120) for conveying the electrical product. The wind turbine airport (100) further comprises an auxiliary power line (102) connected to the first wind turbine (110) and the second wind turbine (120), where the auxiliary power line (102) is configured for delivering auxiliary power for wind turbine maintenance or standby operation to at least one of the first wind turbine (110) and the second wind turbine (120). Furthermore, the wind turbine field (100) comprises an auxiliary power unit (103) for generating auxiliary power, where the auxiliary power unit (103) is connected to the auxiliary power line (102).

Description

Technical Field

[0001] The present invention relates to a wind turbine park and a method of operating a wind turbine park. Background Art

[0002] Very large wind and solar projects (in the gigawatt range) are being planned in rural areas for hydrogen production. For example, large wind and solar hydrogen farm parks are planned in desert areas or other remote locations. Systems located in rural areas are far from electricity consumers and strong grids capable of transmitting large amounts of electricity.

[0003] In particular, if the wind turbine is in a standby operating mode, operating power is required in order to provide maintenance operations such as yaw the nacelle or pitch the blades of the wind turbine. In addition, during the start-up of the wind turbine, additional external power is required in order to provide sufficient energy for the electronic equipment of the wind turbine (such as a heater or a blade pitch system).

[0004] WO 2021 / 151643 A1 discloses a system for mitigating stationary vibrations of a wind turbine. The wind turbine comprises an energy storage system such as a diesel generator. If a disconnection from an auxiliary power grid is detected, the energy storage system may be activated or deactivated. Furthermore, the energy storage system may be applied to the wind turbine, wherein the energy storage system has sufficient energy capacity to provide energy for a known duration when the wind turbine is off-grid.

[0005] However, the corresponding energy storage system and / or generator on each wind turbine is expensive, bulky and complex to maintain, especially in remote areas or offshore wind turbine farms with limited accessibility. In addition, static periods (e.g., a few days during a calm period) are limited by the capacity of the storage system. Summary of the invention

[0006] One object of the present invention may be to provide a more efficient auxiliary power system for a wind turbine park.

[0007] This object is solved by a wind turbine park and a method of operating the wind turbine park according to the subject matter of the independent claims.

[0008] According to a first aspect of the invention, a wind turbine park is described, comprising at least a first wind turbine and a second wind turbine for producing an electric power product, such as electric power or hydrogen. The wind turbine park comprises a main line connecting the first wind turbine and the second wind turbine for delivering the electric power product and an auxiliary power line connected to the first wind turbine and the second wind turbine. The auxiliary power line is configured for delivering auxiliary power for wind turbine maintenance or standby operation to at least one of the first wind turbine and the second wind turbine. The wind turbine park also comprises an auxiliary power unit for producing auxiliary power for the first wind turbine and the second wind turbine, wherein the auxiliary power unit is connected to the auxiliary power line.

[0009] According to another aspect, a method of operating a wind turbine park as described above is provided. The method comprises generating an electric power product by at least one of a first wind turbine and a second wind turbine and transmitting the electric power product via a main line. The method further comprises generating auxiliary power by an auxiliary power unit and transmitting the auxiliary power for maintenance or standby operation to at least one of the first wind turbine and the second wind turbine via an auxiliary power line.

[0010] A wind turbine in a wind turbine farm may include a wind turbine tower and a corresponding nacelle to which rotatable wind turbine blades are coupled. In an operating mode of the wind turbine, as the blades are rotated by wind force, a generator in the nacelle generates direct current and electric power accordingly. The generated electric power is used to generate an electric power product, which can be transported via a main line to a central storage device for electric power products, such as a huge fluid tank or a power battery. In addition, the generated electric power product can also be transported via a main line to an electric power product network, such as an electric power grid or a corresponding pipeline system that transports the electric power product to its final destination.

[0011] The power product generated by the respective wind turbine is defined in the present application as a product generated by the electric power generated by the wind turbine generator and / or output by the wind turbine farm. For example, according to an exemplary embodiment, the power product is a power fluid, in particular a liquid or a gas, wherein the main line is a fluid pipe for conveying the generated power fluid. The power product may be hydrogen or oxygen generated by an electrolyser unit operated by the electric power of the wind turbine.

[0012] Thus, the main line may be a gas line or a liquid fluid line, for example a line for hydrogen or oxygen in liquid or gaseous form.

[0013] Alternatively or additionally, according to another exemplary embodiment, if the wind turbine farm is designed for generating and exporting electrical power, the power product may be the electrical power generated by the generator of the wind turbine. In this case, the main line is a power line for transmitting the generated electrical power. The power line is configured to transmit the huge power generated by the wind turbine generator. The corresponding main power line is designed to transmit the main part of the power generated by the corresponding wind turbine generator. Onshore wind turbines generate 3MW to 5MW. For example, modern offshore wind turbines generate 10MW to 15MW. Therefore, onshore or offshore wind farms generate a total of 10MW to more than 1GW (gigawatts), in particular between 100MW and 300MW. Therefore, the main power line can be designed to transmit more than 10MW (megawatts), in particular more than 100MW, more than 300MW, and more particularly more than 1GW. If the power product is a gaseous medium, the main line is a corresponding main pipe with a corresponding capacity to transport gas from the wind turbine farm.

[0014] In contrast to the main line, the auxiliary power line is designed for providing auxiliary power for maintenance or standby operation of the wind turbines to the first wind turbine and the second wind turbine. The auxiliary power is required for standby operation and maintenance operations, such as yaw the nacelle and pitch the blades, operate a heating unit (e.g., for de-icing the system of the blades), for powering electrical components (e.g., transformers), etc. In particular, during startup of the wind turbine, the auxiliary power is required to power initial startup devices such as the yaw or pitch system.

[0015] For a wind turbine, the auxiliary power required to assist maintenance and standby operation is less than 1 MW. In particular, the auxiliary power is less than 0.5 MW, in particular less than 0.15 MW. In another exemplary embodiment, the auxiliary power line is designed for transmitting a voltage of less than 50 kV, in particular less than 10 kV, more in particular less than 1 kV. Thus, for example, the auxiliary power line is designed to have a smaller capacity and therefore a smaller diameter than the main power line. This enables a more cost-effective auxiliary power cable.

[0016] According to the invention, the auxiliary power line connects the first wind turbine and the second turbine and further in particular connects all wind turbines of the wind turbine park. Hence, all wind turbines of the wind turbine park are coupled to one common auxiliary power line system.

[0017] The respective auxiliary power units are coupled to the auxiliary power lines for generating auxiliary power and for transmitting the auxiliary power to the respective wind turbines. In an exemplary embodiment, the wind turbine farm includes exactly one auxiliary power unit that can be activated for providing auxiliary power. In another exemplary embodiment, another auxiliary power unit may also be provided as a backup system if the main auxiliary power unit fails.

[0018] For example, the auxiliary power unit may include a generator driven by a combustible fuel (e.g., a fossil fuel, such as diesel) or hydrogen / oxygen. Additionally or alternatively, the auxiliary power unit is a fuel cell operated by an electric power product. For example, the auxiliary power unit may be a fuel cell driven by hydrogen and / or oxygen. In this regard, the auxiliary power unit may be driven by a green fuel, which is generated by renewable energy, specifically by solar energy or wind energy, such as generated by wind turbines at a wind turbine farm. Examples of green energy are green hydrogen, methanol or ethanol. In addition, for example, the auxiliary power unit may include a power storage system, such as a rechargeable battery system. According to another exemplary embodiment, the battery can be charged in particular by electrical power generated by at least one of the first wind turbine and the second wind turbine.

[0019] According to the method of the invention, a wind turbine park is provided, which comprises an auxiliary power unit, which provides auxiliary power not only for one wind turbine of the wind turbine park, but also for at least two and, for example, all wind turbines of the wind turbine park. Therefore, it is no longer necessary to provide an auxiliary power unit for each wind turbine of the wind turbine park. Therefore, since the auxiliary power unit is part of the wind turbine park and is coupled to the auxiliary power line, the wind turbine park can be separated from the supply grid.

[0020] Wind turbine parks for producing e.g. hydrogen form so-called off-grid wind turbine parks, which are configured for converting electricity into hydrogen directly at the wind turbine or wind farm level and are therefore not compulsorily coupled to a supply external grid to which the wind farm is connected. Such off-grid wind turbines are specifically configured for producing hydrogen as an electricity product and require a large amount of auxiliary power for stationary periods (e.g. in the absence of wind) and for start-up processes of wind turbine equipment, such as electrolysers and associated process equipment, such as water treatment etc.

[0021] Auxiliary power will also be needed to keep the equipment heated in order to avoid freezing of the process water in the equipment during winter. The invention is particularly advantageous for such off-grid turbines, since it is difficult to supply the required auxiliary power with a simple battery system on each turbine. Having a corresponding auxiliary power unit on each turbine would become too heavy and expensive. Therefore, the corresponding wind turbine farm can be completely separated from such a supply grid and can receive the necessary auxiliary power from an auxiliary power unit, in particular one or another auxiliary power unit as a backup system. Therefore, the described wind turbine farm can be used for wind turbine power plants without a grid connection.

[0022] According to another exemplary embodiment, the auxiliary power line is configured for transmitting less than 1 MW, more particularly less than 500 kW, in particular less than 150 kW. In another exemplary embodiment, the auxiliary power line is designed for transmitting a voltage of less than 50 kV, in particular less than 10 kV, more particularly less than 1 kV. The auxiliary power line can withstand a voltage in the range of, for example, 0.690 kV to 10 kV.

[0023] Thus, for example, the auxiliary power line is designed to have a smaller capacity, and thus a smaller diameter, than the main (power) line. This enables a more cost-effective auxiliary power cable.

[0024] According to another exemplary embodiment, at least one of the first wind turbine and the second wind turbine comprises an electrolyser unit for producing hydrogen and / or oxygen as power fluid. The electrolyser unit may be capable of producing gas with sufficient pressure to deliver the gas to an offshore or onshore facility, so that it is not mandatory to provide a corresponding compressor. However, it is also possible to install an additional compressor in the main line in order to control the efficiency of the gas transport and to control the flow direction of the gas / liquid in the main line.

[0025] The electrolyzer unit is supplied with a starting (basic) material such as water, and produces a corresponding electrolytic fluid, such as a gas, such as hydrogen and oxygen, by using the electric power generated by the wind turbine generator. The basic material can be provided by a supply pipeline, or, for example, in the case of water as a basic material, it can be provided from an ocean / lake / river or groundwater. Specifically, the electrolyzer unit produces a first electrolytic gas, such as hydrogen, which is transported through a main line. In addition, the electrolyzer unit can produce a second electrolytic gas, such as oxygen. The second electrolytic gas can be discharged or can be transported in another main line. The wind turbine may include an optional storage tank for storing power products before being transported through the main line. The storage tank can be integrated in a turbine structure, such as a nacelle, a tower or a foundation of a wind turbine.

[0026] According to another exemplary embodiment, an auxiliary power unit is mounted to a first wind turbine, wherein, in particular, a second and / or all other wind turbines do not have another auxiliary power unit. In this exemplary embodiment, the wind turbine farm comprises exactly one auxiliary power unit that can be activated for providing auxiliary power.

[0027] According to another exemplary embodiment, the auxiliary power unit is mounted to an auxiliary power platform that is separated from the first wind turbine and the second wind turbine. At a central location of the wind turbine park, a corresponding auxiliary power platform may be provided for supporting the auxiliary power unit. The auxiliary power platform may be an offshore platform or an onshore platform, i.e. a corresponding foundation. Thus, a standard wind turbine may be provided without a separate mounting device for supporting the auxiliary power platform.

[0028] According to another exemplary embodiment, a wind turbine park comprises an auxiliary power controller configured to control the auxiliary power provided to a first wind turbine and a second wind turbine (and correspondingly to all other wind turbines of the wind turbine park). The auxiliary power controller is configured to determine the maintenance or standby operation of the first wind turbine and the second wind turbine (and correspondingly all other wind turbines of the wind turbine park). The auxiliary power controller is configured to determine the auxiliary power demand of each single wind turbine and is configured to determine the power output of the auxiliary power unit. Thus, the auxiliary power controller controls the auxiliary power supply to the corresponding wind turbine based on the available generated auxiliary power. For example, if sufficient auxiliary power is available, auxiliary power is supplied to all wind turbines for maintenance and standby operation. If the sum of the required auxiliary power of the wind turbines exceeds the generated auxiliary power, the auxiliary power unit is configured to subsequently transmit the auxiliary power to the corresponding subsequent wind turbines. For example, in a first time period, the first wind turbine receives corresponding auxiliary power through the auxiliary power unit, and if the maintenance and standby operation process of the first wind turbine is completed, then in a second time period, the second wind turbine receives corresponding auxiliary power through the auxiliary power unit.

[0029] According to another exemplary embodiment, the auxiliary power line comprises a predetermined power threshold for the auxiliary power transmitted via the auxiliary power line. The power threshold is in particular less than 500 kW, in particular less than 150 kW. The auxiliary power controller is configured to provide auxiliary power to the first wind turbine and the second wind turbine taking into account the predetermined power threshold.

[0030] According to another exemplary embodiment, the auxiliary power controller is configured to subsequently provide auxiliary power first to the first wind turbine and subsequently to the second wind turbine if the sum of the total required auxiliary powers of the first wind turbine and the second wind turbine exceeds a power threshold of the auxiliary power line.

[0031] According to another exemplary embodiment, the auxiliary power controller is configured for controlling a maintenance or standby operation of at least one of the first wind turbine and the second wind turbine.

[0032] According to another exemplary embodiment, the maintenance or standby operation comprises a plurality of maintenance or standby tasks, in particular pitch control of blades of the wind turbine or yaw control of a nacelle of the wind turbine. The auxiliary power controller is configured to control the timing of these maintenance or standby tasks so as to comply with a power threshold of the auxiliary power line.

[0033] Therefore, if the design of the auxiliary power line does allow only a maximum threshold, the auxiliary power controller controls the auxiliary power in such a way that the maximum threshold of the auxiliary power transmitted through the auxiliary power line is met, i.e., the auxiliary power transmitted through the auxiliary line is lower than the power threshold of the auxiliary power line. Therefore, by means of the auxiliary power controller, defects of the auxiliary power line caused by transmitting too much auxiliary power through the auxiliary power line are avoided.

[0034] Furthermore, according to another exemplary embodiment, the corresponding maintenance and standby operations may be classified and prioritized. For example, the corresponding maintenance and standby operations may have a higher priority than other maintenance and standby operations. For example, pitch control may be required to prevent a dangerous event. If sufficient auxiliary power is not available, the auxiliary power controller first controls the wind turbine to perform only maintenance or standby operations to prevent a dangerous event, and then controls the second wind turbine.

[0035] According to another exemplary embodiment, the wind turbine park is separated from the grid. The grid is defined as a grid provided outside the wind turbine park and the wind turbines are not directly coupled to the grid. For example, the grid operator is the respective power supplier and not the operator of the wind turbine park. Thus, the wind turbine park according to the invention can be operated isolated and self-sufficiently without being connected to an external grid.

[0036] The invention can also be used in HVDC connected wind farms, where the main power supply is a high voltage direct current (HDVC) connection, but an auxiliary power line and an auxiliary power unit are used to supply auxiliary power to the turbines. This is particularly advantageous in the start-up of wind turbines when the DC between the substation of the wind farm and the grid is not established (commissioning) or is not working due to a power outage.

[0037] In summary, the invention solves the problem of having sufficient auxiliary power for standby, starting and / or idling of a wind turbine and / or a plurality of wind turbines despite disconnection of the wind turbine park from the respective supply grid. Thus, in particular in the case of off-grid wind power generation systems, a backup power supply during standstill and starting of remote wind turbines is provided.

[0038] An example of such an off-grid system is a wind turbine that produces hydrogen by electrolysis directly at the wind turbine. The produced hydrogen is exported via a gas pipeline, rather than supplying power to the grid as with a conventional grid-connected turbine. According to the present invention, by providing an auxiliary power line coupled to a corresponding auxiliary power unit, expensive large-capacity power cables and power transmission losses can thereby be avoided.

[0039] It should be noted that embodiments of the present invention have been described with reference to different subject matters. In particular, some embodiments have been described with reference to device type claims, while other embodiments have been described with reference to method type claims. However, those skilled in the art will understand from the above and the following description that, unless otherwise stated, in addition to any combination of features belonging to one type of subject matter, any combination between features related to different subject matters, in particular any combination between features of device type claims and features of method type claims, is also considered to be disclosed by the present application.

[0040] The above-defined aspects of the present invention as well as further aspects will be apparent from the examples of embodiment described hereinafter and will be explained with reference to these examples of embodiment. The present invention will be described in more detail hereinafter with reference to examples of embodiment, but the present invention is not limited to these examples of embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of a wind turbine park according to an exemplary embodiment of the invention is shown.

[0042] Figure 2 A schematic diagram of an auxiliary power controller and an exemplary control process according to an exemplary embodiment of the present invention is shown.

[0043] Figure 3 A schematic diagram showing a cross section of a main line and an auxiliary power line according to an exemplary embodiment of the present invention is shown.

[0044] Figure 4 A schematic diagram of a wind turbine park comprising a plurality of wind turbines connected in series and in parallel according to an exemplary embodiment of the invention is shown. DETAILED DESCRIPTION

[0045] The illustrations in the drawings are schematically. It is noted that in different drawings, similar or identical elements are provided with the same reference signs.

[0046] Figure 1 A schematic diagram of a wind turbine park 100 according to an exemplary embodiment of the present invention is shown. The wind turbine park 100 includes at least a first wind turbine 110 and a second wind turbine 120 for generating an electric power product, and a main line 101 connecting the first wind turbine 110 and the second wind turbine 120 for transmitting the electric power product. The wind turbine park 100 also includes an auxiliary power line 102 connected to the first wind turbine 110 and the second wind turbine 120, wherein the auxiliary power line 102 is configured to transmit auxiliary power for wind turbine maintenance or standby operation to at least one of the first wind turbine 110 and the second wind turbine 120. In addition, the wind turbine park 100 includes an auxiliary power unit 103 for generating the auxiliary power, wherein the auxiliary power unit 103 is connected to the auxiliary power line 102.

[0047] The wind turbines 110, 120, 130 shown in the wind turbine farm 100 include a wind turbine tower and a corresponding nacelle to which rotatable wind turbine blades are coupled. In the operating mode of the wind turbines 110, 120, 130, as the blades are rotated by the wind, a generator in the nacelle generates direct current and electric power accordingly. The generated electric power is used to generate an electric power product, which can be transmitted via the main line 101 to a central storage device for electric power products, such as a huge fluid tank, or an electric power product grid 401 (see Figure 4 ), such as a corresponding pipeline system that outputs the electrical power product from the wind turbine farm 100 to its final destination.

[0048] The power product generated by the respective wind turbines 110, 120, 130 is Figure 1 In the exemplary embodiment shown in FIG. 1 , the power product is a power fluid, and the main line 101 is a fluid pipe for transporting the generated power fluid. The power product is, for example, hydrogen or oxygen produced by an electrolyzer unit 104, which is operated by the electrical power of the corresponding wind turbines 110, 120, 130.

[0049] The auxiliary power line 102 connects the wind turbines 110, 120, 130 and is designed to provide auxiliary power for wind turbine maintenance or standby. The auxiliary power is required for standby operation and maintenance operations, such as yaw the nacelle 107 and pitch the blades 106, operate a heating unit (e.g., for deicing the blade system), power electrical components (e.g., transformers), etc.

[0050] As in Figure 1 As can be seen in the exemplary embodiment of FIG. 8 , all wind turbines 110 , 120 , 130 of a wind turbine park are coupled to one common auxiliary power line 102 .

[0051] exist Figure 1 In the exemplary embodiment of the present invention, one auxiliary power unit 103 is coupled to the auxiliary power line 102 for generating auxiliary power and transmitting the auxiliary power to the corresponding wind turbines 110, 120, 130. In the exemplary embodiment, the auxiliary power unit 103 is installed to the wind turbine 120.

[0052] The wind turbine farm 100 is, for example, an offshore wind turbine farm having power lines 101 and auxiliary power lines 102 below sea level 108 .

[0053] The auxiliary power unit 103 is, for example, a fuel cell driven by hydrogen and / or oxygen produced by the wind turbine 120. The hydrogen and / or oxygen may be a power product produced by the wind turbines 110, 120, 130. For example, the wind turbines 110, 120, 130 include a corresponding electrolyzer unit 104 for producing hydrogen and / or oxygen as power fluid. From the electrolyzer unit 104, the produced hydrogen and / or oxygen is transported out of the wind turbine farm through the main line 101.

[0054] The auxiliary power unit 103 may be a fuel cell and, for example, is coupled to the electrolyzer unit 104 of the wind turbine 120 and / or the adjacent electrolyzer unit 104 of the wind turbines 110 and 130 to receive a corresponding fuel, such as hydrogen or oxygen produced by the electrolyzer 104. Therefore, the auxiliary power unit 103 is coupled to the electrolyzer unit 104 through another source system, or is coupled to the main line 101, for receiving hydrogen and / or oxygen. Specifically, the auxiliary power unit 103 receives hydrogen or oxygen from the electrolyzer unit 104 operated by the wind turbine in operation. Alternatively, the auxiliary power unit 103 may receive fuel (hydrogen or other combustible fuels, such as diesel) from a fuel tank. For example, the auxiliary power unit 103 may include a fuel cell driven by green fuel, which is generated by renewable energy. Therefore, if the auxiliary power unit 103 receives green fuel from the fuel tank, all wind turbines 110, 120, 130 may be in standby mode. The auxiliary power unit 103 may further comprise a battery, wherein the battery may in particular be charged by the electric power generated by at least one of the first wind turbines 110 , 120 , 130 .

[0055] The electrolyzer unit 104 is supplied with a base material (e.g., water) and produces corresponding power products, such as gases, such as hydrogen and oxygen, by using the electric power generated by the wind turbine generators of the wind turbines 110, 120, 130. The base material can be provided by a supply pipeline, or, for example, in the case of water as a base material, it can be provided from an ocean / lake / river or groundwater. Specifically, the electrolyzer unit 104 produces a first electrolysis gas, such as hydrogen, which is transported through the main line 101. In addition, the electrolyzer unit can produce a second electrolysis gas, such as oxygen. The second electrolysis gas can be discharged or can be transported in another main line. The wind turbines 110, 120, 130 may include an optional storage tank for storing power products before being transported through the main line 101.

[0056] Therefore, the auxiliary power unit 103 provides auxiliary power not only to the wind turbine 120 where the auxiliary power unit 103 is installed, but also to the other wind turbines 110, 130 of the wind turbine park 100. Therefore, since the auxiliary power unit 103 is part of the wind turbine park 100 and is coupled to the auxiliary power line 102, the wind turbine park 100 can be separated from the supply grid, and an off-grid wind turbine park 100 configured for converting electricity into hydrogen directly at the location of the wind turbines 110, 120, 130 can be provided.

[0057] The wind turbine park 100 includes an auxiliary power controller 105 configured to control auxiliary power provided to the wind turbines 110, 120, 130. The auxiliary power controller 105 is configured to determine maintenance or standby operation of the wind turbines 110, 120, 130. The auxiliary power controller 105 is configured to determine the auxiliary power demand of each single wind turbine 110, 120, 130 and to determine the power output of the auxiliary power unit 103.

[0058] Figure 2 A schematic diagram of an auxiliary power controller 105 and an exemplary control process according to an exemplary embodiment of the present invention is shown.

[0059] The auxiliary power controller 105 controls the auxiliary power supply to the corresponding wind turbines 110, 120, 130 based on the available generated auxiliary power. For example, if sufficient auxiliary power is available, auxiliary power is supplied to all wind turbines 110, 120, 130 for maintenance and standby operation. If the sum of the required auxiliary power of the wind turbines 110, 120, 130 exceeds the generated auxiliary power, the auxiliary power unit 103 is controlled by the auxiliary power controller 105 for subsequently transmitting the auxiliary power to the corresponding subsequent wind turbines. For example, in a first time period, the first wind turbine 110 receives the corresponding auxiliary power through the auxiliary power unit 103, and if the maintenance and standby operation process of the first wind turbine 110 has been completed, then in a second time period, the second wind turbine 120 receives the corresponding auxiliary power through the auxiliary power unit 103.

[0060] By means of the auxiliary power controller 105, the maximum power capacity of the auxiliary power line 102 may be taken into account, and therefore the auxiliary power line 102 does not have to be designed for an absolute maximum power situation in which all wind turbines 110, 120, 130 receive the maximum required auxiliary power. Therefore, the auxiliary power line 101 comprises a predetermined power threshold for the auxiliary power delivered via the auxiliary power line, which predetermined power threshold may be taken into account by the auxiliary power controller 105. The power threshold for the maximum power transmitted by the auxiliary power line 102 is in particular less than 300 kW.

[0061] For example, a wind turbine 110, 120, 130 may require 150 kW as a maximum for maintenance mode (e.g., for yaw of the nacelle or for pitching of the blades) and approximately 50 kW in standby mode (e.g., for heaters, communication units or other standby devices). The auxiliary power line 102 may be limited in its power capacity by line diameter, material, etc. Therefore, the maximum power capacity defines a threshold. The auxiliary power controller 105 schedules the maintenance mode of the wind turbine 110, 120, 130 and, for example, only allows the maintenance mode of the wind turbine 110, 120, 130 until the threshold of the auxiliary line capacity is not exceeded.

[0062] Thus, in the example of four wind turbines 110, 120, 130, the load example may be: 50 kW + 50 kW + 50 kW + 150 kW = 300 kW, since three wind turbines 120, 130 are in standby mode (50 kW power consumption) and only one wind turbine 110 is in maintenance mode (150 kW power consumption). The wind turbine 110 is operating in maintenance mode, e.g. yaws the nacelle, pitches the blades, operates the heating unit, powers the transformer and other electrical components. Thus, in this example, the 300 kW threshold is not exceeded.

[0063] If needed, the wind turbines 110, 120, 130 request power from the auxiliary power controller 105. The auxiliary power controller 105 schedules activities (standby / maintenance operations) in the wind turbines 110, 120, 130 to prevent the threshold of the maximum power capacity of the auxiliary power line 102 from being exceeded.

[0064] In addition, wind turbines 110 that need auxiliary power or are in a dangerous state are prioritized by the auxiliary power controller 105. For example, other wind turbines 120, 130 located on the same array are set to standby with minimum power consumption so as not to exceed the threshold. The wind turbine 110 can use all the auxiliary power required to do the task. After the task is completed, the other wind turbines 120, 130 can be used again with normal consumption, or can be driven in maintenance mode.

[0065] In summary, if the design of the auxiliary power line 102 does allow only a maximum threshold of the transmitted power, the auxiliary power controller 105 controls the auxiliary power in such a way that the maximum threshold of the auxiliary power transmitted via the auxiliary power line 101 is met.

[0066] Figure 3 A schematic diagram of a cross section of a main line 101 and an auxiliary power line 102 according to an exemplary embodiment of the present invention is shown. An auxiliary cable / line 102 is attached to the main line 101, such as a gas pipeline. In addition, a communication cable (optical fiber) can be integrated in the auxiliary cable 102, or independently attached to the main line 101. The auxiliary power line 102 is configured for transmitting less than 500 kW, in particular less than 105 kW. In another exemplary embodiment, the auxiliary power line 102 is designed for transmitting a voltage of less than 50 kV, in particular less than 10 kV, more in particular less than 1 kV. Therefore, the auxiliary power line 102 is designed to have a smaller capacity and therefore a smaller diameter. As shown from Figure 3 It can be seen that the diameter of the auxiliary power line 102 is much smaller than the diameter of the main line 101 .

[0067] Figure 4A schematic diagram of a wind turbine farm 100 including a plurality of wind turbines 110, 120, 130 connected in series and in parallel according to an exemplary embodiment of the present invention is shown. In this example, four wind turbines 110, 120, 130 are connected in series with a main line 101 and an auxiliary line 102 along a respective string 402. Specifically, more than seven (e.g., 8) wind turbines 110, 120, 130 are connected in series with a main line 101 and an auxiliary line 102 along a respective string 402. The string 402 is connected in parallel with a center string 403. A portion of the main line 101 in the main string 403 is coupled to an external power production grid 401, such as a power grid or a pipeline system, outside the wind turbine farm 100.

[0068] Thus, in particular, the auxiliary lines 102 may be connected by a loop configuration to enable a large cluster of wind turbines 110 , 120 , 130 that may be operated together by the auxiliary power generated by a common auxiliary power unit 103 .

[0069] It should be noted that the term "comprising" does not exclude other elements or steps, and the wording "a", "an" or "an" does not exclude a plurality. Furthermore, elements described in connection with different embodiments may also be combined. It should also be noted that the reference numerals in the claims should not be interpreted as limiting the scope of the claims.

Claims

1. A wind turbine farm (100), comprising: at least a first wind turbine (110) and a second wind turbine (120) for generating an electric power product, a main line (101) connecting the first wind turbine (110) and the second wind turbine (120) for transmitting the electric power product, an auxiliary power line (102) connected to the first wind turbine (110) and the second wind turbine (120), wherein the auxiliary power line (102) is configured to transmit auxiliary power for wind turbine maintenance or standby operation to at least one of the first wind turbine (110) and the second wind turbine (120), an auxiliary power unit (103) for generating the auxiliary power for the first wind turbine (110) and the second wind turbine (120), Wherein, the auxiliary power unit (103) is connected to the auxiliary power line (102).

2. The wind turbine farm (100) according to claim 1, in, The auxiliary power line (102) is configured for transmitting less than 1 MW, more particularly less than 500 kW, in particular less than 150 kW.

3. The wind turbine park (100) according to claim 1 or 2, in, The power product is electric power, The main line (101) is a power line for transmitting the generated electric power.

4. The wind turbine park (100) according to claim 1 or 2, in, The power product is a power fluid, in particular a liquid or a gas, Wherein, the main line (101) is a fluid pipe used to transport the generated power fluid.

5. The wind turbine park (100) according to claim 4, in, At least one of the first wind turbine (110) and the second wind turbine (120) comprises an electrolyser unit (104) for producing hydrogen and / or oxygen as a power fluid.

6. A wind turbine park (100) according to any one of claims 1 to 5, in, The auxiliary power unit (103) is mounted to the first wind turbine (110), In particular, the second wind turbine (120) is free of a further auxiliary power unit (103).

7. A wind turbine park (100) according to any one of claims 1 to 5, in, The auxiliary power unit (103) is mounted to an auxiliary power platform spaced apart from the first wind turbine (110) and the second wind turbine (120).

8. A wind turbine park (100) according to any one of claims 1 to 7, in, The auxiliary power unit (103) is a battery, wherein the battery is in particular chargeable by electric power generated by at least one of the first wind turbine (110) and the second wind turbine (120), and / or Wherein, the auxiliary power unit (103) is a fuel cell operated by the electric power product.

9. The wind turbine park (100) according to any one of claims 1 to 8, further comprising: an auxiliary power controller (105) configured to control auxiliary power provided to the first wind turbine (110) and the second wind turbine (120), The auxiliary power controller (105) is configured to determine maintenance or standby operation of the first wind turbine (110) and the second wind turbine (120).

10. The wind turbine park (100) according to claim 9, in, The auxiliary power line (102) includes a predetermined power threshold for auxiliary power delivered via the auxiliary power line (102), The power threshold is in particular less than 500 kW, in particular less than 150 kW, The auxiliary power controller (105) is configured to provide auxiliary power to the first wind turbine (110) and the second wind turbine (120) taking into account the predetermined power threshold.

11. The wind turbine park (100) according to claim 10, in, The auxiliary power controller (105) is configured to firstly provide auxiliary power to the first wind turbine (110) and then provide auxiliary power to the second wind turbine (120) if the sum of the total auxiliary power required by the first wind turbine (110) and the second wind turbine (120) exceeds a power threshold of the auxiliary power line (102).

12. A wind turbine park (100) according to claim 10 or 11, in, The auxiliary power controller (105) is configured to control a maintenance or standby operation of at least one of the first wind turbine (110) and the second wind turbine (120).

13. The wind turbine park (100) according to claim 12, in, The maintenance or standby operation comprises a plurality of maintenance or standby tasks, in particular a pitch control (106) of the blades of the wind turbine or a yaw control (107) of the nacelle of the wind turbine, The auxiliary power controller (105) is configured to control the timing of the maintenance or standby task so as to comply with a power threshold of the auxiliary power line (102).

14. A wind turbine park (100) according to any one of claims 1 to 13, in, The wind turbine farm (100) is isolated from a power grid.

15. A method of operating a wind turbine park (100) according to any one of claims 1 to 14, the method comprising: generating an electric power product by at least one of the first wind turbine (110) and the second wind turbine (120), transmitting the electric power product through a main line (101), generating auxiliary power through an auxiliary power unit (103), Auxiliary power for maintenance or standby operation is delivered to at least one of the first wind turbine (110) and the second wind turbine (120) through an auxiliary power line (102).

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