JP3576262B2 - GFRP-made wind turbine blade capable of predicting fracture and method of predicting its fracture - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a wind turbine blade made of GFRP that can be predicted to be broken for wind power generation.
[0002]
[Prior art]
Conventionally, as wind turbine blades for wind power generation, as shown in FIG. 2 (A) longitudinal sectional view and FIG. 2 (B) BB perspective sectional view, outer skins 1 and 2 forming an airfoil shape, and mainly strength members A wing composed of a main girder 3 having a box-shaped cross section, which is a long cylindrical member having a rectangular frame-shaped cross section, and urethane foams 4, 5 serving as an intermediate filler is used. Here, GFRP (Glass Fiber Reinforced Plastic) is used for the outer shells 1 and 2 and the main girder 3 from the viewpoint of weight reduction, high strength and low cost.
[0003]
[Problems to be solved by the invention]
In order to improve the power generation efficiency, for example, a 250 kW class wind turbine blade has a blade of about 12 m and a rotating diameter of about 28 m in order to improve power generation efficiency. There is a tendency. Therefore, a plastic composite material (FRP) is used as the blade material from the viewpoint of weight reduction and high strength.
In addition, the blades of the windmill receive a tensile load due to centrifugal force and a repeated bending load by rotating and receiving the wind. In addition, since durability of at least 10 years has recently been required to be guaranteed, it is necessary to ensure reliability against blade fatigue damage.
Therefore, it is necessary to ensure the fatigue strength of the blades. However, since the GFRP blades for wind turbines are large products with a length of more than 10 m, there is a variation in manufacturing. Several broken and scattered cases have been reported. If the wing breaks during rotation due to fatigue damage and its tip breaks and scatters, centrifugal force causes the wing to be scattered due to centrifugal force. Considering a collision is very dangerous and a big problem. Therefore, it is very important to at least capture the damage information before the wing breaks and scatters, and to reliably prevent only the breakage accident during operation (while the wing is rotating).
[0004]
The present invention has been proposed in view of such circumstances, and it is possible to detect internal damage of a wing at an early stage and to prevent an accident such as breakage or scattering of the wing from occurring during rotation. An object of the present invention is to provide a GFRP wind turbine blade capable of predicting fracture and a method of predicting its fracture.
[0005]
[Means for Solving the Problems]
For this purpose, the wind turbine blade made of GFRP with predictable fracture according to the first aspect of the present invention has a long main girder having a box-shaped cross section extending over the entire length of the blade from the blade root to the tip of the blade. The leading edge wing and the trailing edge wing protrude over the entire length of the wing, and the outer surfaces of the leading edge wing, the trailing edge wing, and the main girder are adhesively coated with a skin over the entire length. In a wind turbine blade, a wing made of a thin wire or a long foil having a small cross section, which is embedded in an adhesive layer that bonds the back surface and the abdominal surface of the main girder to the outer skin and is continuously stretched from the blade root portion to the blade tip, respectively. The present invention is characterized in that one long conductive linear material that is multiply folded with the entire length as a unit length is provided.
[0006]
According to a second aspect of the present invention , there is provided a wind turbine blade made of a predictable fracture type GFRP according to the first aspect of the present invention , wherein a plurality of resistance measurement terminals stored in a blade root portion are provided. It is characterized in that both ends of the measuring conductive wire are connected to the respective terminals for resistance measurement.
[0007]
The wind turbine blade made of GFRP with predictable fracture according to the invention of claim 3 is the wind turbine blade made of GFRP with predictable fracture according to claim 1, wherein the plurality of GFRP wind turbine blades are coaxially arranged in parallel with the rotation center bosses of the plurality of blade roots. The present invention is characterized in that a resistance value of each of the long conductive linear members can be always measured while the windmill is rotating, by providing a slip ring and a brush contacting each of the slip rings.
[0008]
The method for predicting the destruction of a GFRP wind turbine blade according to the invention of claim 4 is the method for predicting the destruction of a GFRP wind turbine blade that is predictable for destruction according to claim 1, wherein the operation of the wind turbine blade is periodically stopped, It is characterized in that the electric resistance of the long conductive linear material is measured, and the wing breakdown is predicted based on a change in the measured value.
[0009]
[Action]
According to such a configuration, the form of the conductive material embedded in the wing is a thin wire or thin plate that does not impair the strength of the GFRP wing material, such as metal fiber, foil, or carbon fiber. is there. The embedding position is preferably in the vicinity of the surface of the portion where the induced stress of the blade during operation is the highest and the amount of deformation is large, for example, in the adhesive layer between the outer skin and the main girder.
In the present invention, by measuring the electric resistance of the conductive material disposed inside the wing, slight damage to the wing can be detected, and before the worst accident of breaking or scattering of the wing during operation is caused. In addition, measures can be taken.
[0010]
【Example】
One embodiment in which the present invention is applied to a 250 kW class wind turbine will be described with reference to the drawings. FIG. 1 is a perspective view showing a cross-sectional view of the wind turbine blade.
[0011]
In the figure, the same reference numerals as in FIG. 2 each represent the same members of the same figure, when the present invention is greatly different from the structure of Figure 2 in the adhesive layer portion between the main girder-hull, wire diameter φ1.5mm certain copper back of the main girder 3, it was ChoSo continuously from embedded to the blade tip in the adhesive layer 6, 7 until the blade root between the ventral surface and its outer skin 1.
[0012]
From the ventral side of this prototype wing, cut out a large fatigue test piece (length: 600 mm, width: 120 mm, plate thickness: 20 mm) including the outer skin, adhesive layer (including copper wire), and main girder, and test after processing As a result of measuring the electric resistance of one copper wire, it was 1.6 to 1.7 μΩ · cm.
[0013]
Next, after measuring the electric resistance, a tensile fatigue test was performed. The tensile load stress was 0.3 to 3.0 kg / mm ² repeatedly, and the electrical resistance of the copper wire was continuously recorded.
As a result, when the number of repetitions exceeded 2 × 10 ⁶ , the electric resistance of the copper wire became Δ and it was confirmed that the copper wire was broken.
Then, when the specimen was observed in detail, many fine cracks were generated at the center of the specimen. One of them was about 5 mm long and the depth was the thickness of the specimen. It has grown to 1/3 of the thickness, and it was found that the embedded copper wire was broken at this portion.
[0014]
In view of the above, a plurality of conductive lines having conductivity from the blade tip to the blade root are mounted on the adhesive layer between the main girder and the outer skin of the GFRP blade, and the electrical resistance is measured. It has been confirmed that before the worst case of scattering occurs, it is possible to detect damage to the conductive resistance wire and take a countermeasure.
By laying a continuous line along the entire length of the wing along the abdominal surface, the back surface and / or the leading and trailing edges of the wing, whether the damage occurs on the abdominal surface, the back surface, or on the leading or trailing edge Can also be detected.
[0015]
【The invention's effect】
According to the present invention, it is possible to detect the initial damage of the wing by measuring the electric resistance of a long conductive material stretched and buried in a form in which the entire length is bent multiple times in the longitudinal direction inside the wing, Countermeasures can be taken before the worst case of wing breakage and splashing occurs. In addition, there is no need to perform regular damage inspection (visual inspection, non-destructive inspection) of the wing, which has been performed at a considerable cost, so that maintenance inspection costs can be significantly reduced.
[0016]
In short, according to the wind turbine blade made of GFRP with predictable fracture according to the first aspect of the present invention, foam is formed on the front end face and the rear end face of a long main girder having a box-shaped cross section extending from the root to the tip of the blade. A GFRP formed by projecting a leading edge wing portion and a trailing edge wing portion made of urethane over the entire length of the wing, and adhesively coating the outer surfaces of the leading edge wing portion, the trailing edge wing portion, and the main girder with a skin over the entire length. Wind turbine blades, which are embedded in an adhesive layer that adheres the back and abdominal surfaces of the main girder to the outer skin, and are each composed of a small-section thin wire or long foil that is continuously stretched from the blade root to the blade tip. full length single elongated conductive linear member multiplexed folded so Bei Eteiru as a unit length of the blade, by detecting the internal damage of the blade at an early stage accident Oridan-scattering and the like of the blade during rotation Safety that can be prevented from occurring From getting destroyed predictable type GFRP wind turbine blade and fracture prediction method, the present invention is extremely useful industrially.
[0017]
According to the wind turbine blade made of predictable fracture type GFRP of the invention of claim 2, in the wind turbine blade made of predictable fracture type of GFRP according to claim 1, a plurality of resistance measurement terminals stored in the blade root portion are provided, Both ends of the long conductive wire are connected to the resistance measurement terminals, respectively, so that internal damage to the wing is detected early and accidents such as wing breakage or scattering occur during rotation. The present invention is extremely industrially useful because it is possible to obtain a safe and predictable GFRP wind turbine blade that can prevent the occurrence of a failure and that can easily measure the resistance value of the conductive linear material. is there.
[0018]
According to the wind turbine blade made of predictable fracture type GFRP according to the invention of claim 3, in the wind turbine blade made of predictable fracture type of GFRP according to claim 1, the plurality of blade roots are coaxially arranged in parallel with the rotation center boss. each example Bei abutting brushes in a plurality of slip rings and the respective slip rings, since the resistance value at all times each of the elongated conductive wire-like material during rotation of the wind turbine was possible to measure the internal damage of the blade early detects can accidents Oridan-scattering and the like of the blade to prevent the occurrence during rotation, it is possible to measure the electric resistance value even during the rotation of the blades, need to perform periodic inspection The present invention is extremely useful in the industry because it provides a safe and predictable GFRP wind turbine blade that can eliminate the cost and greatly reduce the maintenance cost.
[0019]
According to the method for predicting destruction of a GFRP wind turbine blade according to the invention of claim 4, it is the method for predicting destruction of a GFRP wind turbine blade capable of predicting destruction according to claim 1, wherein the operation of the wind turbine blade is periodically stopped. By measuring the electrical resistance of the long conductive wire and predicting the destruction of the wing based on a change in the measured value, internal damage to the wing can be detected early to break the wing. The present invention is extremely useful in industry because it provides a safe and predictable method for predicting the destruction of GFRP wind turbine blades, which can prevent accidents such as scattering during rotation.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a cross section of a prototype GFRP blade of an embodiment in which the present invention is applied to a wind turbine for wind power generation having a power of 250 kW.
FIG. 2 shows an FRP blade of a conventional wind turbine for power generation, wherein FIG. 2 (A) is a cross-sectional view of the FRP blade, and FIG. 2 (B) is a perspective view showing a BB transverse section thereof.
[Explanation of symbols]
1 dorsal skin (GFRP)
2 Ventral outer skin (GFRP)
3 Main girder (GFRP)
4 Trailing edge wing urethane foam 5 Leading edge wing urethane foam 6 Back adhesive layer (GFRP)
7 Ventral adhesive layer (GFRP)
8 Leading edge
9 Trailing edge (trailing edge)
10. Back copper wire (φ1.5mm)
11 ventral copper wire (φ1.5mm)

Claims (4)

A long main girder with a box-shaped cross section extending from the root of the blade to the tip of the blade has a box-shaped cross-section. In addition, in the wind turbine blade made of GFRP, the outer surface of the leading edge wing portion, the trailing edge wing portion, and the outer surface of the main girder are adhesively covered with a skin over the entire length, the back surface and the abdominal surface of the main girder are bonded to the outer skin. A single long conductive linear wire buried in the adhesive layer and multiply folded with the entire length of the wing consisting of a small cross-section fine wire or long foil continuously stretched from the root of the blade to the tip of the blade. characterized in that e Bei the timber, breaking foreseeable type GFRP made wind turbine blades. 2. The GFRP wind turbine blade according to claim 1, further comprising a plurality of resistance measuring terminals stored in a root portion of the blade, wherein both ends of the long conductive wire are respectively connected to the respective resistance measuring terminals. A wind turbine blade made of GFRP that can be predicted to be destroyed, characterized by being connected to a wind turbine blade. In breaking predictable type GFRP made wind turbine blade according to claim 1, e Bei respectively abut brush rotation center boss of the plurality of blade root portion coaxially arranged a plurality of slip rings and the respective slip rings are A wind turbine blade made of GFRP with predictable fracture, characterized in that the resistance value of each of the long conductive wires can be constantly measured while the wind turbine is rotating. A method for predicting breakage of a wind turbine blade made of rupture predictable type GFRP according to claim 1, wherein the operation of the wind turbine blade is periodically stopped, and the electric resistance of the long conductive wire is measured. A GFRP wind turbine blade destruction prediction method characterized by predicting blade destruction based on a change in the measured value.

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