JP2018040280A - Receptor fitting structure of windmill blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent damage of a receptor, which is attached to a windmill blade of a wind power generation device, and its periphery due to lightning.SOLUTION: A receptor fitting structure to a windmill blade is configured such that to a surface of a blade 4 comprising an insulation material, a plate-like receptor 6 having conductivity, connected to a down-conductor and constituting a lightening receiving part is attached, wherein an outer peripheral edge side on a fitting surface of the receptor 6 to the surface of the blade 4 and the surface of the blade 4 closely contact with each other, or an interval between the outer peripheral edge side of the fitting surface of the receptor 6 and the surface of the blade 4 is kept so as to be equal to or less than 0.1 mm.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a receptor mounting structure for a wind turbine blade in a wind turbine used as a wind power generator or various power sources.

  Conventional lightning generators have lightning damages ranging from minor damages such as charring on the blade surface to fatal ones such as blade explosions. In particular, for a large-scale steam explosion in a wind power generator, it is known that lightning current is applied to moisture that has entered the cavity in the blade, causing extremely serious damage that causes the blade itself to explode. In Japan, the energy of winter lightning is very large, and there are many cases where receptor tolerance is insufficient.

  On the other hand, a small-scale steam explosion occurred around the receptor, and the dissolution of the receptor was observed in this area, but the extent was relatively minor and the location was limited to the vicinity of the receptor. However, the wind power generation function was not greatly affected, and it was apt to be overlooked.

  However, damage or melting of the receptor may cause serious damage due to subsequent lightning strikes.Even if the damage is small, damage to the blade during lightning strikes becomes serious if the receptor function is lost. Even small-scale damages to the receptor and the receptor require repairing the generator and working at a high altitude in poor working conditions such as the summit and hills.

  On the other hand, as shown in Patent Documents 1 and 2, there are known an embedded type in which a part of the receptor is exposed and embedded on the surface of the blade, and a plate-like receptor that is bolted to the surface. However, any of the receptors has a problem that a lightning strike causes damage to the blade surface around the receptor and the receptor itself, and a sufficient solution has not been obtained.

JP 2009-250040 A Japanese Patent Laying-Open No. 2007-120393 (see FIG. 1B)

  A water vapor explosion around the receptor occurs when moisture is present as a series circuit on the lightning current conduction path. That is, the water vapor explosion does not occur when lightning current flows around a conductor other than moisture, but occurs when electricity flows directly into moisture itself.

  Among the above-described receptors, rainwater accumulates in the gap between the recessed portion for embedding or the inner peripheral wall of the recessed portion and the receptor. On the other hand, the blade is made of gas fiber reinforced plastic, etc., and is an insulator, but the blade surface becomes conductive due to dust from dirt in the atmosphere and carbide from lightning, etc. There is a disadvantage that steam explosion on the blade surface tends to occur.

  Further, as will be described in detail later, in the case of a surface-mounted plate type receptor, a caulking for waterproofing is applied between the outer periphery and the blade surface. Rainwater enters due to deterioration, ultraviolet light deterioration, etc., and a circuit that conducts lightning current between the blade and the receptor is formed by the interaction with dirt, carbide, etc. It was discovered that it may explode with loss.

  Based on the above knowledge, the present invention prevents the entry of water that forms a lightning current circuit between the blade surface and the mounting surface (overlapping surface) of the receptor, or minimizes the amount of the penetration, thereby reducing the amount of the small scale. It prevents steam explosion and damages of the receptor and blade surface.

  The receptor mounting structure according to the present invention for solving the above-mentioned problem is as follows. First, a plate-like receptor 6 that has conductivity and is connected to a down conductor to form a lightning receiving portion on the surface of the blade 4 made of an insulating material. The attachment structure of the receptor to the windmill blade to which the outer peripheral edge of the receptor 6 is attached to the surface of the blade 4 and the surface of the blade 4 is in close contact with each other. The gap S between the outer peripheral edge side of the blade and the surface of the blade 4 is maintained at 0.1 mm or less.

  Secondly, the surface of the blade 4 to which the receptor 6 is mounted is curved to form a gentle curve, and either one or both of the attachment surfaces of the receptor 6 and the blade 4 are adjusted in advance so that both surfaces are matched. It is characterized by that.

  Third, the surface of the blade 4 to which the receptor 6 is attached is curved to form a gentle curve, and the receptor 6 is formed of a rigid material in the shape of a disk having a thickness of 1 to 6 mm and a diameter of 30 to 80 mm. It is said.

  Fourth, the receptor 6 is made of a composite material obtained by sintering a metal and a carbon material, and the carbon material contained in the composite material is 10 to 80% by volume based on the total volume of the composite material and It is characterized by being sintered to 95% or more of the ideal density.

  Fifth, the carbon material includes scaly graphite powder, and the scaly graphite powder has a scaly shape defined by a normal vector having an inclination of 20 ° or more with respect to the normal vector of the easy heat conduction surface. A first scaly graphite powder having a surface and a second scaly graphite powder having a scaly surface defined by a normal vector having an inclination of 10 ° or less, and the scaly shape of the first scaly graphite powder. The content rate with respect to the whole graphite powder is 12% or less, The content rate with respect to the whole scale-like graphite powder of the said 2nd scale-like graphite powder is 55% or more, It is characterized by the above-mentioned.

  According to the receptor mounting structure of the present invention configured as described above, the blade surface and the overlapping surface of the receptor mounting are brought into close contact as much as possible, or the gap between the outer peripheral edge of the receptor mounting surface and the blade surface is 0.1 mm or less. Since the retention of moisture between both surfaces can be zero or minimized by holding, steam explosion due to the accumulated moisture between both surfaces can be prevented. In general, either one or both of the surface of the wind turbine blade that gently curves from the center to the tip and the mounting surface of the plate-like receptor are adjusted and matched in advance, so that the adhesion between both surfaces is high. In addition, the receptor mounting surface is maintained while maintaining the mechanical strength (rigidity) of the mounted receptor by setting the plate thickness of the receptor to 1 to 6 mm and the diameter to 30 to 80 mm with respect to the curved blade surface. It is possible to keep the gap between the outer peripheral edge of the blade and the blade surface to a minimum.

  Furthermore, by using the composite material of the metal and carbon material according to claims 4 and 5 as the receptor material, a certain mechanical strength required for the receptor is ensured, and heat dissipation during lightning due to high thermal conductivity is obtained. In addition, by conducting heat in the radial direction from the center of the disc-shaped receptor to the outer periphery to dissipate heat, higher heat radiation can be achieved, and melting of the receptor and blade can be prevented.

It is a whole front view of a wind power generator (windmill). It is a partial expanded side view of a wind power generator (windmill). (A) is sectional drawing which shows the receptor attachment structure of this invention, (B) is the top view similarly. (A), (B) is a schematic explanatory drawing of the adhesion structure of the receptor attachment surface which shows the other Example of this invention. (A), (B is principal part sectional drawing and top view which show the receptor attachment structure which concerns on the other Example of this invention. (A) is a perspective view of the equipment used for the experiment of the subject of this invention and an effect confirmation, (B)-(D) is a top view which shows the method of the said experiment. (A)-(C) is a schematic cross-sectional view of a receptor attached state showing an experimental method for confirming the problems and effects of the present invention from different viewpoints. (A) and (B) show the damaged state of the aluminum tape and the damaged state of the receptor, respectively, in the case where the damage experiment was conducted with the receptor embedded. (A) shows the damaged state on the blade substitute substrate side after the experiment shown in FIG. 8, and (B) shows the damaged state on the receptor side.

  1 and FIG. 2 show an embodiment of the present invention, and the apparatus shown in FIG. 1 is a wind power generation apparatus (windmill) most widely used at present. A plurality of blades 4 arranged radially at equal angular intervals are supported rotatably on the upper part of the support column 1 by a wind power shaft 3 via a nacelle 2. Each blade 4 is made of an FRP insulator and has a hollow structure.

  As shown in FIG. 3, the blade 4 has a lightning receiving portion at the time of a lightning strike, and a receptor 6 made of a disk-shaped conductive plate is fastened and fixed by a bolt 7. It is made of metal (conductor) such as stainless steel, and its inner end is connected to a lightning conductor (down conductor) 8 wired in the blade 4, and the lightning current input to the receptor 6 passes through the receptor 4 and the lightning conductor 8. Grounded.

  In addition, a guide tape 9 made of a metal tape radially attached around the receptor 6 is provided around the receptor 6 on the surface of the blade 4 so that a lightning strike can occur from a wide area around the receptor 6. The lightning current is induced toward the receptor 6 and is electrically connected to the receptor 6.

  The material of the receptor 6 can be selected from copper, stainless steel, aluminum or the same alloy. In this embodiment, the receptor 6 is made of a composite material obtained by sintering a metal and a carbon material, and the carbon material contained in the composite material. Used is sintered to 10 to 80% by volume based on the total volume of the composite material and to 95% or more of the ideal density.

  The carbon material includes scaly graphite powder, and the scaly graphite powder has a scaly surface defined by a normal vector having an inclination of 20 ° or more with respect to the normal vector of the easy heat conduction surface. 1 scale-like graphite powder and at least two kinds of scale-like graphite powder having a scale-like surface defined by a normal vector with an inclination of 10 ° or less are included, and the entire scale-like graphite powder of the first scale-like graphite powder The content of the second scaly graphite powder with respect to the whole scaly graphite powder is 55% or more.

  The metal-graphite composite material has a thermal conductivity of 500 W / mK or more in at least one direction of the material, and the metal can be selected from copper, silver, aluminum, or an alloy material mainly containing any of these. As described above, the volume content of graphite is 10 to 80%, desirably 30 to 70%. And it has a high heat conduction direction from the disk shape toward the outer peripheral side.

  The receptor 6 is made of a conductor disposed in the blade 4 and is fastened and fixed to the surface of the blade 4 with a metal bolt 7 to a fixing block (not shown) connected to the lightning conductor 8 described above. 7 is preferably austenitic stainless steel considering the weather resistance and conductivity balance. After the receptor 6 is attached, the corner portion between the outer peripheral surface and the blade 4 surface is waterproofed (waterproof portion 11) with a caulking material. Incidentally, the waterproof part 11 is formed over the entire outer peripheral side of the receptor 6.

  When the receptor 6 is mounted on a lightly curved region of the mounting surface of the blade 4 and a gently curved surface (on the average, many of them have a radius of curvature of about 2000 mm), the surface of the blade 4 in the receptor 6 In order to prevent water from entering between the mounting surface and the surface of the blade 4, it is necessary to keep the gap S on the outer peripheral edge side between both surfaces to a minimum (0.1 mm or less).

  For this reason, it is desirable to keep the diameter (D) in the range of 30 to 80 mm for the purpose of reducing the bending moment applied to the receptor 6 as the radius from the fixed portion at the center of the receptor 6 decreases. The shape of the selector 6 is not limited to a circle, but may be a square shape or other polygonal shape. In this case, it is desirable that the size in the longitudinal direction be within the above range.

  In addition, the plate thickness (t) is in the range of 1 to 6 mm (preferably 3 to 5 mm) in consideration of the mechanical strength and weather resistance of the receptor 6 and the wind pressure resistance at the time of rotating operation. Ideally. And the clearance gap S hold | maintained to the minimum (specifically 0-0.1 mm) is formed in the range covering the perimeter of the outer periphery side of the receptor 6. FIG.

  Further, as described above, it is desirable that the contact state between the attachment surface on the outer peripheral edge side of the receptor 6 and the surface of the blade 4 is zero so that there is no gap S that may be submerged. Therefore, as shown in FIG. The mounting surface of the receptor 6 is formed into a concave surface of a curve that conforms to the curvature of 4 (the radius of curvature R), or the mounting surface of the blade 4 is replaced with the mounting surface (plane) of the receptor 6 as shown in FIG. It is desirable to form on a flat surface according to the above. Needless to say, both sides can be adjusted and matched to each other, and these can also be performed by adjusting the polishing during the mounting operation.

  In the above-described example, the guide tape 9 is provided up to a range up to the surface opposite to the attachment surface of the receptor 6 (non-attachment surface). However, in the example shown in FIG. The receptor 6 and the guide tape 9 may be non-contact. If comprised in this way, it can prevent efficiently that water intervenes between the non-attachment surface of the receptor 9, and the induction | guidance | derivation tape 9, and water vapor | steam explosion generate | occur | produces.

I. FIG. 6 is a diagram for explaining the contents and results of an experiment for confirming under what conditions water vapor explosion occurs when water is present in the vicinity of the receptor, among the problems of the present invention. FIG.
FIG. 2A shows an outline of the equipment used in this experiment, and the contents of the equipment used and the experiment method are as follows.
1. Equipment used (1) Frame material 21 Transparent acrylic plate
・ Thickness 1mm
・ Width 60mm
・ Vertical width 30mm
(However, 40mm is used in the experiment of Fig. (C))
・ Size of cutout window 21a 40 × 10 (mm)
(However, in the experiment of Fig. (C), 40mm x 20mm is used)
(2) Lid 22 Transparent acrylic plate
・ Thickness 1mm
・ Width 60mm
・ Vertical width 30mm
(However, 40mm is used in the experiment of Fig. (C))
(3) Substrate 23 Made of insulating FRP and having a size of 60 × 40 (mm) (4) Aluminum tape 24 Thickness 0.1 mm, width 5 mm
(5) Impulse high current generator (not shown)

2. Experimental Method As shown in FIGS. 6B, 6C, and 6D, the frame material 21 is placed on the substrate 23, and the aluminum tape 24 is bonded and fixed along the longitudinal direction in the cutout window 21a. A large impulse current is applied to both ends of an aluminum tape 24 which is covered with a lid material 22 placed on the frame material 21 in a state where a water drop 26 (0.1 ml) is hung on or near the upper portion of the aluminum tape 24. A large current was passed by connecting electrode terminals of a generator (not shown). The current is increased every 1 kV (about 1.2 kA at 1 kV), and each pattern shown in FIGS. 6B to 6D is simulated by flowing a lightning current in a state where water has entered each frame member 21. Was observed.
Details of the patterns in FIGS. 6B to 6D are as follows.
i) In FIG. 6B, a state in which the water droplet 26 is hung on the aluminum tape 24,
ii) In FIG. 5C, a state in which the water droplet 26 is hung at a position away from the aluminum tape 24,
iii) In FIG. 4D, a certain space is provided between the butted ends of the aluminum tape 24 cut to the left and right, and the water droplets 26 are arranged in close contact with each other in a non-contact state, and each is energized.

3. Experimental Results (1) When energized in a pattern in which water droplets 26 hang down on the aluminum tape 24 shown in FIG. 4B, the clouding starts at about 6 kA, the aluminum tape 24 melts at about 13.2 kA, and the lid 22 The water droplet adhesion range on the inner surface has been expanded.
(2) When energized in a pattern in which water droplets 26 were hung in the vicinity of the aluminum tape 24 shown in FIG. 4C, the aluminum tape 24 was melted at about 13.2 kA, and no change in water was observed.
(3) In the pattern in which water droplets are arranged between the left and right aluminum tapes shown in FIG. 4D, light is emitted and explosive sound is emitted through the water droplets 26 when energizing about 7.2 kA, and the lid 22 is blown off to evaporate the water. did.

4). Consideration of Experimental Results (1) When a lightning current flows through the aluminum tape 24 serving as a down conductor, rapid volume expansion is unlikely to occur due to the generated Joule heat.
(2) Water is instantaneously evaporated and expanded due to discharge through water.
(3) When a large current flows through the down conductor and receptor through water due to winter lightning, it is considered that water evaporates and expands in the portion through the water.

II. Damage experiment in which high pressure current is applied to receptor in contact with moisture. Experimental method (1) Materials for experimental equipment ・ Receptor 6 Material Copper-carbon composite sintered material (trade name “STC-CH”)
Diameter D = 60mm
Thickness t = 5mm
・ Blade substitute substrate 4 Plywood Same size on the surface of 15 × 200 × 300 (mm)
Plate material to which FRP of 1mm thickness is fixed ・ Bolt 7 for fixing and grounding 15mm brass bolt ・ Down conductor (aluminum tape) 9 thickness 0.1mm, width 50mm
・ Caulking material (waterproof part 11)
-Absorbent cotton impregnated with moisture-Current surge generator (10 / 350μs) Model ICG-200K24μ
-350-110q (Otowa Electric Industry)
・ Digital oscilloscope type TDS3054C (manufactured by Tektronix)
・ Current transformation type 4424 (Pearson)
・ Optical fiber isolation system Model PH-A360-041
-200 (manufactured by Photonics)
(2) Experimental method In any of the samples shown in FIGS. 7A to 7C, the receptor 6 is bolted to the surface of the substrate 4 and the outer periphery of the receptor 6 is formed with a waterproof part 11 using a caulking material. Both were subjected to simulated lightning (150 kA) using the current surge generator. The conditions specific to each sample are as follows.
i) In the case of the sample in FIG. 7 (A) Aluminum tape 9 is attached to the surface of the receptor 6 and the surface of the substrate 4 on the outer periphery thereof, and water 12 is infiltrated between the overlapping surfaces of the receptor 6 and the substrate 4. The aluminum tape 9 was caused to receive light by interposing.
ii) In the case of the sample in FIG. 7B, a washer-like spacer 13 having a thickness of 0.5 mm is inserted between the receptor 6 and the substrate 4, and moisture 12 is stored on the outer periphery thereof. A lightning current was applied directly (as a light receiving part) (however, the aluminum tape 9 was not arranged).
iii) In the case of the sample of FIG. 7C In this example, an aluminum tape 9 is stuck on the surface of the substrate 4, and its end is between the outer peripheral edge of the attachment surface of the receptor 6 and the attachment surface of the substrate 4 ( A water layer 12 ′ formed by impregnating absorbent cotton with water is interposed between the aluminum tape (down conductor) 9 and the mounting surface of the receptor 6 (in contact with both surfaces) (the aluminum tape 9 and the receptor). 6 was conducted through the moisture layer 12 '), and a lightning current was applied using the aluminum tape 9 as a lightning receiving portion.

2. Experimental Results (1) In the experiment shown in FIG. 7A, the aluminum tape 9 was partly peeled off, but the shape of the receptor 6 itself was maintained and no breakage occurred. Similarly, in FIG. 7B, the shape of the receptor 6 itself was maintained and no breakage occurred.
(2) On the other hand, in the experiment shown in FIG. 7C, the results of applying the lightning current differed due to the difference in the overlap width W between the peripheral edge of the receptor 6 attached to the surface of the substrate 4 and the aluminum tape 9.
That is, when the overlap width W was 10 mm and 30 mm, the moisture in the moisture layer 12 ′ was instantly expanded (exploded), and the side of the receptor 6 that was overlapped with the aluminum tape 9 was broken and exploded as the aluminum tape 9 was dissolved and peeled. On the other hand, when the overlapping width W between the moisture layer 12 'and the aluminum tape 9 was 5 mm, the receptor 6 was not damaged or expelled.

3. Consideration of Experimental Results According to the above experimental results, as a condition that the surface of the receptor 6 or the blade 4 is damaged by a steam explosion (expansion) during a lightning strike, some conductive layer on the surface of the blade 4 (Note: dirt and moisture on the surface of the blade 4) It can be inferred that a certain amount or more of moisture is present between the receptor 6 and the receptor 6 and that the moisture constitutes a lightning current circuit.
In relation to the amount of water, the smaller the diameter of the receptor 6 is, the more advantageous for the angled surface of the blade 4, and it is desirable that the diameter is also small in relation to the bending moment applied to the receptor 6 when the moisture expands. It is clear that the mechanical strength plate thickness of the receptor 6 is desirably kept above a certain level.

III. Experiment of damage to buried receptor Experimental Method (1) Experimental Equipment Material ・ Receptor 31 Material Copper-Carbon Composite Sintered Material (trade name “STC-CH”)
Diameter D = 20mm
・ Blade substitute board 32 Plywood
Plate thickness = 20mm
FRP with a thickness of 3 mm is fixed on the surface.-Fixing and grounding bolts 33 Brass bolts-Aluminum tape 34 Thickness 0.1 mm, width 50 mm
· Absorbent cotton 36 impregnated with moisture
(2) Experimental method As shown in FIG. 8, the receptor 31 is disposed in the insertion hole 32 a having a diameter of 22 mm formed in the blade representative substrate 32 so as to be at the same center. A small-diameter screw portion 31a is inserted into a screw hole 33a formed in the head of the bolt 33, and is screwed and fixed. In this state, a 1 mm gap S ′ is formed between the receptor 31 and the insertion hole 32a. In this gap S ′, absorbent cotton 36 is provided in contact with the aluminum tape 34, a voltage is applied to the aluminum tape 34 side, a current of 160 A is passed, and the subsequent state is observed.

2. Experimental Results As shown in FIG. 9A, it was confirmed that a steam explosion occurred and the aluminum tape 34 was damaged. In addition, as shown in FIG. 5B, it is confirmed that the upper surface of the receptor 31 is partially broken, and the receptor 31 and the bolt 33 are partially melted and slightly fixed. confirmed.

3. Consideration of Experimental Results According to the above experimental results, it was confirmed that even when the receptor 31 is embedded, the receptor 31 itself and the aluminum tape 34 that leads to the receptor 31 are damaged.

4 Blade 6 Receptor 7 Bolt S Clearance

Claims (5)

  A structure for attaching a receptor to a windmill blade, in which a plate-like receptor (6) which is electrically conductive and connected to a down conductor and constitutes a lightning-receiving portion is attached to the surface of a blade (4) made of an insulating material. The outer peripheral edge side of the attachment surface of the receptor (6) to the blade (4) surface and the blade (4) surface, or the outer peripheral edge side of the attachment surface of the receptor (6); A wind turbine blade receptor mounting structure in which the clearance (S) between the blade (4) and the surface is maintained at 0.1 mm or less.   The surface of the blade (4) to which the receptor (6) is attached is curved in a gentle curve, and either one or both of the mounting surfaces of the receptor (6) and the blade (4) are fitted in advance so that both surfaces are fitted. The wind turbine blade receptor mounting structure according to claim 1, which is adjusted.   The surface of the blade (4) for mounting the receptor (6) is curved in a gentle curve, and the receptor (6) is formed of a rigid material in the shape of a disk having a thickness of 1 to 6 mm and a diameter of 30 to 80 mm. Item 3. A wind turbine blade receptor mounting structure according to Item 1 or 2.   The receptor (6) is made of a composite material obtained by sintering a metal and a carbon material, and the carbon material contained in the composite material is 10 to 80% by volume based on the total volume of the composite material and has an ideal density. The wind turbine blade receptor mounting structure according to any one of claims 1 to 3, wherein the wind turbine blade is sintered to 95% or more.   The carbon material includes scaly graphite powder, and the scaly graphite powder has a scaly surface defined by a normal vector having an inclination of 20 ° or more with respect to the normal vector of the easy heat conduction surface. 1 scale-like graphite powder and at least two kinds of scale-like graphite powder having a scale-like surface defined by a normal vector with an inclination of 10 ° or less are included, and the entire scale-like graphite powder of the first scale-like graphite powder The receptor mounting structure for a wind turbine blade according to claim 4, wherein the content of the second scaly graphite powder is 55% or more with respect to the whole scaly graphite powder.