Wind turbine blade

Abstract

Wind turbine blade with de-icing and / or anti-icing system comprising at least one heating unit (5) arranged along the length of the blade and between the chords of the blade, wherein each heating unit (5) in turn comprises a plurality of heating elements (7) connected in series and in parallel in a matrix configuration by means of overlaps (9) or cross-adjacent junctions (8) between adjacent heating elements (7) in order to vary the electric heating current, thus eliminating any additional terminal cables, and also enabling the generation of a gradually increasing heat flux from the blade root (1) towards the blade tip (2) and from the trailing edge (4) towards the leading edge (3) by each individual heating unit (5), thus precisely adapting the heat flux demand and therefore reducing the energy consumption for de-icing and / or anti-icing.

Description

Technical Field

[0001] This invention relates to the technical field of wind turbine blades with de-icing and / or anti-icing systems. More specifically, the invention relates to a wind turbine blade comprising at least one heating unit disposed along the length of the blade and between the chords of the blade, wherein each heating unit further comprises a plurality of heating elements connected in series and in parallel in a matrix configuration by means of overlapping portions or cross-adjacent joints between adjacent heating elements.

[0002] The overlap allows for changes in the electric heating current, thereby eliminating the need for any additional terminal cables, and also enables the generation of gradually increasing heat flux from the blade root toward the blade tip and from the trailing edge toward the leading edge, thus more precisely adapting to specific heat flux requirements and therefore reducing energy consumption for de-icing or anti-icing. Background Technology

[0003] Wind turbine blades are the core components of modern wind turbines used to capture wind energy. The aerodynamic characteristics of the blades have a crucial impact on the efficiency of the wind turbine. When wind turbines operate in rainy or snowy weather, or in wet environments during cold seasons, ice can form on the surface of the blades. Icing alters the existing aerodynamic shape of the blades, which can impair the safe operation of the wind turbine. After the blade surface freezes, its natural frequency changes, altering the dynamic response behavior of the blades and interfering with the control behavior of the control system. The structural integrity of the wind turbine itself is also affected by frozen blades. The effects of imbalance or asymmetry increase the fatigue load on the wind turbine.

[0004] By arranging a heating layer on the surface or inner layer of the blade, the blade can be heated when icing is about to occur to prevent ice from freezing to the surface, or heating can begin after the surface has frozen to melt the ice layer and achieve de-icing. Existing heating and anti-icing systems use heating units that are evenly distributed on the surface of the blade or divided into several heating zones along its length.

[0005] The required heat power per square meter varies along the blade, being lower at shorter radii near the blade root and higher towards the blade tip. Similarly, the required heat flux is higher closer to the leading edge and gradually decreases toward the trailing edge.

[0006] Furthermore, it can be observed that the surface to be heated covers the leading edge up to a certain distance toward the trailing edge, and this distance may not be constant along the blade.

[0007] Therefore, the electrical power to be released for de-icing or anti-icing systems should be precisely optimized for the heat required at each part of the blade to achieve higher efficiency in the heating system and thus lower energy consumption, thereby delivering more energy output to the grid. For example, the power to be released in cold climates can reach tens of kilowatts at harsh temperatures below -5°C. Optimized de-icing or anti-icing solutions can significantly reduce the released power by up to approximately 20-50%.

[0008] Some systems for this purpose are known in the prior art. For example, European document EP2738383A1 discloses a solution for modifying the resistance from the root to the tip of the blade, i.e., the width of the carbon fiber fabric, to increase the heating power along the blade. However, in this solution, the surface to be heated may not meet the corresponding heat flux requirements, and even if the surface is suitable for de-icing, the heat flux may not be perfectly adjusted to meet the required heat flux. Simply changing the width may not accurately match the gradual heat flux requirements, whether in the radial direction or the chordal direction of the blade.

[0009] Other solutions involve using multiple resistors and supplying different voltages to them, so that different resistors with the same resistance receive different currents. The problem with this is that it increases the number of wires needed to supply the different resistors.

[0010] Other solutions disclose modifying the resistors in a parallel configuration to accommodate varying heat flux requirements along the blade while maintaining an equal input voltage for all resistors. However, this solution does not progressively increase the thermal surface density along each individual resistor, resulting in inefficiency along the longitudinal direction of each individual resistor. Furthermore, layers can be connected to account for heat flux requirements along the chord from the leading edge to the trailing edge, but this would require significantly more resistor terminals, increasing proportionally with the number of layers. This is a significant drawback considering that each resistor terminal may be connected to a conductor from the inner surface of the blade. Summary of the Invention

[0011] This paper discloses a wind turbine blade that has been found to at least mitigate the aforementioned drawbacks associated with existing technology solutions.

[0012] More specifically, a wind turbine blade is provided, comprising a blade root, a blade tip, a leading edge, and a trailing edge, and further comprising:

[0013] - Includes at least one heating unit with two terminals, said heating unit being adapted to be powered by an electric heating current, and disposed between the blade root and the blade tip, and between the leading edge and the trailing edge.

[0014] Each heating unit includes multiple heating elements, which are arranged in a matrix configuration of parallel and series connections by means of at least one series overlap between adjacent heating elements connected in series and at least one cross-adjacent joint between adjacent heating elements connected in parallel.

[0015] By connecting these multiple heating elements via an overlap, the electric heating current can be varied without adding additional terminal cables. This is a significant advantage in terms of ease of assembly, considering that each resistor terminal can be connected to the conductor from the inside of the blade's inner surface.

[0016] Furthermore, the multiple heating elements can be connected in parallel and in series, wherein by changing the number of rows or columns in the matrix structure, each heating unit can adapt to the heating flux requirements in each longitudinal and cross-sectional section along each individual heating unit, while eliminating the need to add additional terminal cables for each layer or each heating element that is “overlapping” in parallel or series.

[0017] Furthermore, it can be achieved more precisely by changing the specific resistance of each individual heating element according to the construction of the matrix, so that each heating unit can be constructed to generate a precisely increased heat flux from the blade root to the blade tip and from the trailing edge to the leading edge in each individual heating unit, thereby precisely adapting to the heating requirements in each section of the blade, thereby reducing the energy consumption of the wind turbine and increasing energy output.

[0018] Preferably, the overlapping area can be achieved using simple overlap. Therefore, the cross-adjacent joint can be a cross-overlapping area between heating elements. Alternatively, the cross-adjacent heating elements can be separated from each other by a certain distance or be directly adjacent or overlapping without any distance.

[0019] Therefore, two heating elements connected in parallel can be placed overlapping, directly adjacent, or even with a gap of a few millimeters between them. Preferably, this distance can be between 0 and 50 mm.

[0020] Alternatively, in embodiments involving overlapping portions between parallel-connected heating elements, the overlapping portions may have a length between 0 and 20 cm. More preferably, the overlapping portions may have a length in the range of 0-3 cm.

[0021] For overlaps in the longitudinal direction of current flow, i.e., series overlaps, it may be necessary to use additional conductive elements that can overlap with adjacent heating elements. These additional conductive elements may have a strip geometry or an equivalent geometry to engage the two heating elements by overlapping with both. The use of such additional conductive elements may also be feasible for cross-overlapping heating elements.

[0022] The overlapping portion of a series-connected heating element can be defined as the overlapping area of ​​the series connection, and may include a length of at least 0.5 cm.

[0023] Each individual heating element contained in the heating unit can vary the following parameters: material, thickness, length and / or width, in order to change each specific resistance to adapt to flux requirements, i.e. to produce a precise and gradually increasing heating flux from the blade root to the blade tip and from the trailing edge to the leading edge.

[0024] More specifically, any combination of changes to the parameters can be performed to optimize and more accurately adapt to the precise heat flux requirements at each individual section of the blade.

[0025] The electric heating current can be applied relative to the blade in the longitudinal direction. In this case, when the heating elements are connected in series through the overlapping portion, each heating unit can have a higher resistance toward the blade tip, and when the heating elements are connected in parallel in this case, they have a lower resistance toward the blade leading edge.

[0026] Alternatively, the electric heating current can also be applied along the cross-sectional direction of the blade. In other words, the terminals of the heating unit can be installed along the longitudinal or radial direction of the blade.

[0027] Furthermore, the wind turbine blade may also include more than one heating unit arranged along the blade. Preferably, the plurality of heating units are connected in parallel with the same input voltage.

[0028] Note that in this solution, the resistance of each heating unit should preferably decrease longitudinally to increase heating power. However, each individual electrical unit will also provide a gradually varying heat flux along the chord and longitudinal direction of the blade, thus precisely adapting to the required heat flux and thereby improving thermal power efficiency and reducing energy consumption for de-icing or anti-icing. Furthermore, there is no need to install additional terminal cables, which are inconvenient to connect to conductors on the inner surface of the blade.

[0029] With the above solution, where the neutral cable is also used as the lightning protection system cable in the smart wind turbine blade, it may only be necessary to have an additional conductor to power all heating units, more specifically, extending from the blade root to the last installed heating unit, thereby providing the same voltage to all heating units installed along the blade.

[0030] Alternatively, if the neutral cable is not also a lightning protection cable, then only two additional conductors may be needed to power the heating unit.

[0031] This allows for a greater number of conductors, which can lead to better control over the surface power density or heat flux along the blade. Therefore, each heating unit can be powered individually using a different voltage. In this case, the gradient of heat flux along the chord and radial directions through each individual heating unit is still achieved, and this can lead to higher accuracy and therefore higher efficiency, but at the cost of more conductor cables and easier assembly to connect more terminal cables to the inner surface conductors.

[0032] Preferably, the heating element is a conductive fabric composite material or coating. Attached Figure Description

[0033] To supplement the ongoing description and to aid in a better understanding of the features of the invention, a set of accompanying drawings is provided as part of the description, featuring preferred examples of actual embodiments of the invention, in an illustrative and non-limiting manner:

[0034] Figure 1 The figure shows the heat loss along the radius of a conventional wind turbine blade for multiple temperature increases.

[0035] Figure 2a The diagram illustrates a first preferred configuration, which clearly shows multiple heating units arranged along the longitudinal direction of the blades.

[0036] Figure 2b The diagram illustrates a second preferred configuration, which clearly shows a single heating unit arranged along the longitudinal direction of the blade.

[0037] Figure 3 The illustration shows a first preferred embodiment of the heating unit, which clearly shows six heating elements connected in series and in parallel via string overlap and cross-adjoining junctions, respectively.

[0038] Figure 4 The illustration shows a second preferred embodiment of the heating unit, which clearly shows six heating elements with variable width and material.

[0039] Figure 5 The illustration shows a third preferred embodiment of the heating unit, which clearly shows six heating elements, wherein the width of two individual elements is variable along their length. Detailed Implementation

[0040] With the aid of the above-described drawings, a detailed description of examples of preferred embodiments of the objects of the present invention is provided below.

[0041] Figure 1The diagram illustrates the heat loss along the radius of a conventional wind turbine blade for multiple temperature increases. Thus, it shows how the heat flux requirement, and therefore the precise heat flux that should ideally be produced, gradually changes as the blade radius increases.

[0042] In addition, the heat flux requirement gradually increases from the trailing edge to the leading edge (not shown), and further, it can be found that the surface to be heated covers the leading edge until a certain distance toward the trailing edge, and said distance may not be constant along the blade.

[0043] Therefore, it is evident that optimizing the heat flux generated in each individual segment along the radius of the blade, as well as in the chord of each individual segment of the blade, is of significant importance in reducing the energy consumption for de-icing and anti-icing.

[0044] Figure 2a The diagram illustrates a first preferred configuration, which clearly shows a wind turbine blade including a blade root (1), a blade tip (2), a leading edge (3), and a trailing edge (4).

[0045] Figure 2a The diagram also shows a wind turbine blade comprising multiple heating units (5), each heating unit (5) comprising two terminals (6), the heating unit (5) being adapted to be powered by an electric heating current via a conductor (C), and wherein each heating unit (5) is disposed longitudinally between the blade root (1) and the blade tip (2) and also between the leading edge (3) and the trailing edge (4).

[0046] in addition, Figure 2a The illustration shows that each heating unit (5) includes multiple heating elements (7).

[0047] Figure 2b The diagram illustrates a second preferred configuration, which clearly shows that the wind turbine blade includes a single heating unit (5) extending to the blade tip (2).

[0048] Figure 3 A detailed schematic diagram of a first preferred embodiment of a single heating unit (5) according to the first construction described above is shown. This is a case where multiple heating units (5) are arranged along the blade.

[0049] More specifically, Figure 3 A single heating unit (5) is clearly shown, comprising six heating elements (7) arranged in parallel and series in a matrix configuration by means of a series overlap (9) between adjacent heating elements (7) connected in series and a cross-adjacent joint (8) between adjacent heating elements (7) connected in parallel.

[0050] Figure 3The heating unit (5) depicted in the diagram is capable of changing the electric heating current (I) without including additional terminal cables. This is a significant advantage because each terminal cable would have to be connected to a conductor located on the inner surface of the blade, which would have caused considerable inconvenience in assembling the heating system to the wind turbine blade.

[0051] In addition, by changing the resistance of each heating element (7), the heating unit (4) can also precisely generate an increased heat flux from the root (1) of the blade toward the tip (2) and from the trailing edge (4) toward the leading edge (3) through each heating unit (5). That is, along the longitudinal direction of the blade and also along the chord.

[0052] exist Figure 3 In the first preferred embodiment shown, this is achieved by changing the material and / or geometry of the heating element (5), and thus modifying its resistivity and therefore its resistance.

[0053] More specifically, in the first preferred embodiment, heating elements E1 and E3 are made of the same material, as are E4 and E6, but are made of different materials between each group. Heating elements E2 and E5 each comprise another different material. Thus, the linear resistivity and therefore the resistance are varied and optimized according to the desired heat flux at the precise radius and chord portion of the blade.

[0054] In addition, the width of the elements has been modified, particularly the widths of elements E2 and E5, which are reduced compared to the widths of elements E1, E3, E4, and E6. Similarly, the aim is to optimize the required heat flux at each precise section of the blade.

[0055] Note that by optimizing the resistance of each individual heating element (7) according to a specific configuration, the heating flux can be precisely optimized by each single heating unit (5), and thus more precisely optimized along the longitudinal and cross-sectional directions of the blade.

[0056] Figure 3 It is also shown that the cross-adjacent joint (8) between elements E1 and E4 and E2 is a cross-overlapping part, while the cross-adjacent joint (8) between elements E4 and E6 and E5 is an adjacent joint without any gap or overlap.

[0057] Figure 4 A detailed schematic diagram of a second preferred embodiment of a single heating unit (5) according to the aforementioned first construction is shown.

[0058] More specifically, Figure 4The six heating elements (7) are clearly shown in a matrix configuration of parallel and series arrangement by means of the series overlap (9) between adjacent heating elements (7) connected in series and the cross-adjacent joint (8) between adjacent heating elements (7) connected in parallel.

[0059] exist Figure 4 In the second preferred embodiment shown, the widths of heating elements E4 and E6 decrease linearly along the length of the heating element (7), thereby increasing the resistance as the width decreases.

[0060] Furthermore, heating elements E1 and E3 are made of the same material, as are E4 and E6, but they differ from each other in material or geometry. Heating elements E2 and E5 each comprise an additional material or geometry that differs from those previously mentioned.

[0061] In addition, Figure 4 The diagram shows that the cross-adjacent joints of E4 and E6 with E5 are 0 mm. Nevertheless, note that even a separation of a few millimeters may be feasible for cross-adjacent joints (not shown).

[0062] Figure 5 Another preferred embodiment of the heating unit (5) is illustrated. From Figure 5 As can be seen, matrix construction does not require an equal number of rows and columns.

[0063] More specifically, Figure 5 Heating elements E1 and E3 are shown directly connected to terminal (6), wherein the width of heating elements E1 and E3 decreases linearly along their respective lengths. Furthermore, heating elements E1 and E3 have the same material and resistivity, and subsequently overlap with elements E2, E4 and E5, which each comprise different materials and lengths.

[0064] Figure 5 An additional conductive element (10) overlapping both heating elements E4 and E5 is also shown. This can be achieved between two overlapping heating elements (7) in series (8) by means of a metal mesh or any other conductive sheet, fabric or mesh. The use of a metal mesh between two overlapping heating elements (7) can only be applied to those heating elements that are in the lateral direction relative to the current flow, which is for heating elements (7) that are overlapping in series (9).

[0065] Note that in any of the preferred embodiments described, the heat flux can be optimized along each individual heating element (5), and thus, extremely precise gradient heat flux along each individual section of the blade can be achieved to accommodate the heat flux required for ideal conditions. In other words, by modifying the number of heating elements (5) connected in series and parallel, and thus modifying the matrix configuration, and further modifying the material, width, and / or thickness of each heating element (5), a very precise distribution of the heat flux to be generated along the blade can be achieved, thereby very precisely accommodating the ideal heat flux requirements. Therefore, the energy consumption for de-icing and anti-icing can be greatly reduced, and thus, the energy output and the output to the grid can be greatly increased. This is achieved without increasing the number of terminal cables (6) for each heating element (5).

Claims

1. A wind turbine blade, comprising a blade root (1), a blade tip (2), a leading edge (3), and a trailing edge (4), and further comprising: - At least one heating unit (5) including two terminals (6), said at least one heating unit (5) being adapted to be powered by an electric heating current, and disposed between the root (1) and the tip (2) of the blade and between the leading edge (3) and the trailing edge (4). Each heating unit (5) includes a plurality of heating elements (7) arranged in a matrix configuration in parallel and series between the two terminals, such that one or more first heating elements among the plurality of heating elements (7) are connected in series to one or more adjacent second heating elements among the plurality of heating elements through at least one series overlap (9), and are connected in parallel to one or more adjacent third heating elements among the plurality of heating elements through at least one cross-adjacent joint, thereby allowing for changes in the electric heating current, thereby eliminating any additional terminal cables, and also enabling the generation of a precisely increased heat flux from the blade root (1) toward the blade tip (2) and from the trailing edge (4) toward the leading edge (3) through each heating unit (5).

2. The wind turbine blade according to claim 1, wherein, The overlapping portion (9) of the string includes a length of 0.5-20 cm.

3. The wind turbine blade according to claim 2, wherein, The overlapping portion (9) of the string includes a length of 1-3 cm.

4. The wind turbine blade according to claim 1, comprising at least one additional conductive element (10) overlapping with two adjacent heating elements (7).

5. The wind turbine blade according to claim 1, wherein, The cross-adjacent joint (8) is the cross-overlapping part between adjacent heating elements (7), and the cross-overlapping part includes a length of 0.5-3 cm.

6. The wind turbine blade according to claim 1, wherein, The cross-adjacent joint (8) includes a spacing distance between adjacent heating elements (7), the spacing distance including a length between 0 and 50 mm.

7. The wind turbine blade according to claim 1, wherein, Each heating element (7) includes the following parameters: Width (w), length (L), thickness (t), and resistivity (ρ), and each heating element (7) within the heating unit (5) includes a variable combination of the parameters.

8. The wind turbine blade according to claim 1, wherein, The electric heating current (I) is applied in the longitudinal direction.

9. The wind turbine blade according to claim 8, wherein, Each heating unit (5) has a higher resistance toward the tip (2) of the blade.

10. The wind turbine blade according to claim 8, wherein, Each heating unit (5) has lower resistance facing the leading edge of the blade (3).

11. The wind turbine blade according to claim 1, wherein, The electric heating current is applied in the lateral direction.

12. The wind turbine blade according to claim 1 further includes a plurality of heating units (5) arranged in parallel along the blade.

13. The wind turbine blade according to claim 12, wherein, Each heating unit (5) is supplied with a different voltage individually.

14. The wind turbine blade according to claim 1, wherein, The heating element (7) is a conductive fabric composite material or coating.

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