Lightning protection device and lightning protection method for wind turbine blade

Abstract

To provide a lightning protection device and a lightning protection method for wind turbine blades, which can prevent electric discharge from occurring at the broken point of a down conductor when lightning strikes a wind turbine blade, and can detect a break in the down conductor without working at a high place or using a large-scale device.SOLUTION: A lightning protection device for a wind turbine blade comprises a down conductor 10b that is arranged inside the wind turbine blade 10 and extends along the longitudinal direction of the wind turbine blade 10, and a conductor 10c that is arranged inside the wind turbine blade 10 and extends along the longitudinal direction of the wind turbine blade 10 while being insulated from the down conductor 10b. One end of the down conductor 10b and one end of the conductor 10c are electrically connected to a receptor 10a of the wind turbine blade 10. In addition, the other end of the down conductor 10b is electrically connected to a wind turbine tower 1 that works as a ground conductor, the other end of the conductor 10c is electrically connected to the other end side of the down conductor 10b, and a lightning arrester 11 is interposed on the other end side of the conductor 10c.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a lightning protection device and a lightning protection method for dissipating lightning current to the ground when lightning strikes a wind turbine blade. [Background technology]

[0002] FIG. 6 shows a schematic diagram of an example of a wind power generation device. The wind power generation device is composed of a wind turbine tower 1 erected on the ground G, a nacelle 2 attached to the top of the wind turbine tower 1, and a wind turbine rotor 3 rotatably attached to one end of the nacelle 2 as main elements. The nacelle 2 houses required electrical equipment such as a generator, an electrical circuit, and a control panel. The wind turbine rotor 3 is composed of a hub 3a and a plurality of wind turbine blades 3b attached radially to the hub 3a, for example, three wind turbine blades 3b attached at equal intervals in the rotation direction, and the hub 3a is connected to the rotating shaft of the generator in the nacelle 2. When the wind turbine rotor 3 rotates due to the wind force, the rotation is input to the generator in the nacelle 2 via the hub 3a, which rotates the generator to generate electricity.

[0003] The wind turbine blade 3b of the above-mentioned wind power generation device is provided with a receptor (lightning receiving part) 3b1 and a down conductor (down conductor) 3b2 to protect the wind turbine blade 3b from lightning strikes. The receptor 3b1 is provided at the tip of the wind turbine blade 3b, and when lightning strikes the wind turbine blade 3b, the lightning strikes the receptor 3b1. One end of the down conductor 3b2 is electrically connected to the receptor 3b1, and the other end is electrically connected to the wind turbine tower 1 as a ground conductor (if a ground conductor is arranged inside the wind turbine tower 1, the down conductor may be connected to the ground conductor). When lightning strikes the receptor 3b1, the lightning current is released to the ground G via the receptor 3b1 → down conductor 3b2 → wind turbine tower 1.

[0004] If a break occurs in the down conductor of a wind turbine blade due to aging or a lightning strike, a discharge (arc discharge) will occur at the break in the down conductor when lightning strikes the receptor, leading to damage to the wind turbine blade, etc. For this reason, the guidelines for regular inspections of wind power generation equipment were revised in April 2017, making it mandatory to conduct continuity tests, etc. on the down conductors of wind turbine blades to check their soundness (presence or absence of breaks).

[0005] Various methods have been proposed to detect a break in the down conductor. For example, in Patent Document 1, a measurement cable is placed inside a wind turbine blade, and the measurement cable is used to measure the electrical resistance of the down conductor to check whether the down conductor functions properly. One end of the down conductor is connected to a receptor at the tip of the wind turbine blade, and the other end of the down conductor is connected to a terminal block at the base end of the wind turbine blade. In addition, one end of the measurement cable is connected to the down conductor via the receptor, and the other end of the measurement cable is detachably connected to the above-mentioned terminal block. When measuring the electrical resistance of the down conductor, the other end of the measurement cable is removed from the terminal block, and an electrical resistance measuring device is connected to the other end of the measurement cable and the terminal block. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2012-42473 A Summary of the Invention [Problem to be solved by the invention]

[0007] In conventional methods such as that described in Patent Document 1, a break in the down conductor can be detected during mandatory periodic inspections, but it is possible that the break in the down conductor may go unnoticed and be left unattended before the inspection. In this case, if lightning strikes a wind turbine blade, a discharge occurs at the break in the down conductor, leading to damage to the wind turbine blade.

[0008] An object of the present invention is to provide a lightning protection device and a lightning protection method for a wind turbine blade, which can prevent discharge from occurring at the broken point of the down conductor when lightning strikes a wind turbine blade, and can detect a broken down conductor without working at height or using large-scale equipment. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides a lightning protection device for a wind turbine blade, comprising: a down conductor arranged inside the wind turbine blade and extending along the longitudinal direction of the wind turbine blade; and a conductor arranged inside the wind turbine blade and extending along the longitudinal direction of the wind turbine blade while being insulated from the down conductor, wherein one end of the down conductor and one end of the conductor are each electrically connected to a receptor of the wind turbine blade, the other end of the down conductor is electrically connected to a ground conductor, the other end of the conductor is electrically connected to the side of the other end of the down conductor, and a lightning arrester is interposed on the side of the other end of the conductor.

[0010] Furthermore, in order to solve the above-mentioned problems, the present invention provides a lightning protection method for a wind turbine blade, comprising: arranging a down conductor extending along the longitudinal direction of the wind turbine blade; and a conductor extending along the longitudinal direction of the wind turbine blade while being insulated from the down conductor inside the wind turbine blade, electrically connecting one end of the down conductor and one end of the conductor to a receptor of the wind turbine blade, electrically connecting the other end of the down conductor to a ground conductor, electrically connecting the other end of the conductor to a side of the other end of the down conductor, and interposing a lightning arrester on the side of the other end of the conductor, and when there is no break in the down conductor, causing a lightning current that has struck the receptor to flow to the ground conductor via the down conductor, and when there is a break in the down conductor, causing the lightning current that has struck the receptor to flow to the ground conductor via the conductor and the lightning arrester. Effect of the Invention

[0011] According to the present invention, it is possible to provide a lightning protection device and a lightning protection method for wind turbine blades that can prevent discharge from occurring at the broken point of the down conductor when lightning strikes a wind turbine blade, and that can detect a broken down conductor without working at height or using large-scale equipment. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating a wind turbine blade according to an embodiment. [Diagram 2] FIG. 13 is a diagram showing the operation when lightning strikes a receptor with no break in the down conductor. [Diagram 3] FIG. 13 is a diagram showing the operation when lightning strikes a receptor with a broken down conductor. [Figure 4] FIG. 11 is a diagram showing a manner in which the presence or absence of conduction between the primary side and the secondary side of the lightning arrester in a conductor is confirmed. [Diagram 5] FIG. 13 is a diagram showing an embodiment in which a surge counter is interposed on the secondary side of a lightning arrester in a conductor. [Figure 6] FIG. 1 is a diagram illustrating an example of a wind power generating device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] FIG. 1 shows a schematic diagram of a wind turbine blade 10 of a wind turbine rotor in a wind power generation device as shown in FIG. 6. The wind turbine blade 10 is formed into a hollow shape from an insulating material such as fiber reinforced plastic (FRP). A receptor 10a is provided at the tip of the wind turbine blade 10 (multiple receptors may be provided along the longitudinal direction of the wind turbine blade 10), and a down conductor 10b and a conductor 10c are disposed inside the wind turbine blade 3b. The conductor 10c is formed from a bare conductor or a coated conductor, a metal workpiece or a metal part (including those coated with insulation), or the like. In this embodiment, the conductor 10c is formed from a coated conductor.

[0015] The down conductor 10b extends along the longitudinal direction of the wind turbine blade 10, with one end electrically connected to the receptor 10a at the tip of the wind turbine blade 10, and the other end extending from the base end of the wind turbine blade 10 to the nacelle 2 (see FIG. 6) side and electrically connected to the wind turbine tower 1 as a ground conductor.

[0016] The conductor 10c extends in parallel with the down conductor 10b along the longitudinal direction of the wind turbine blade 10 while being insulated from the down conductor 10b. One end of the conductor 10c is electrically connected to the receptor 10a at the tip of the wind turbine blade 10, and the other end of the conductor 10c extends from the base end of the wind turbine blade 10 to the nacelle 2 (see FIG. 6) side and is electrically connected to the other end of the down conductor 10b (connection part 10d). As a result, the other end of the conductor 10c is electrically connected to the wind turbine tower 1 as a ground conductor via the connection part 10d and the other end of the down conductor 10b. Furthermore, a lightning arrester (SPD) 11 is interposed on the other end of the conductor 10c. As is well known, a lightning arrester (SPD) is a device that contains one or more nonlinear elements {MOV (metal oxide varistor), GTO (gas discharge tube), ABD (avalanche breakdown diode), TSS (surge protection thyristor), etc.}. Due to the effect of the nonlinear elements, a lightning arrester (SPD) normally functions as an insulator that does not conduct electricity (high resistance), but when an overvoltage such as a lightning surge occurs, it instantly changes from high resistance to low resistance, and has the function of passing the lightning current to the ground side.

[0017] As described above, the impedance of the conductor 10c becomes larger than that of the down conductor 10b due to the lightning arrester 11 being interposed on the other end side of the conductor 10c. Therefore, as shown in Fig. 2, when lightning strikes the receptor 10a with no break in the down conductor 10b, the lightning current I (or most of the lightning current I) flows from the receptor 10a to the down conductor 10b, and then flows from the down conductor 10b to the wind turbine tower 1 and is discharged to the ground G as usual.

[0018] On the other hand, as shown in Fig. 3, when lightning strikes the receptor 10a with a break in the down conductor 10b, a lightning surge (overvoltage) is applied to the arrester 11 interposed in the conductor 10c, and the arrester 11 instantly changes from high resistance to low resistance. Therefore, the lightning current I flows from the receptor 10a to the conductor 10c and the arrester 11, and then flows from the connection part 10d and the other end of the down conductor 10b to the wind turbine tower 1 and is discharged to the ground G. In this way, even if lightning strikes the wind turbine blade 10 with a break in the down conductor 10b, the lightning current I flows to the wind turbine tower 1 via the conductor 10c and the arrester 11, so that no discharge occurs at the break in the down conductor 10b, and the wind turbine blade 10 is protected from the lightning. Incidentally, it is desirable that the operating voltage of the arrester 11 (the voltage at which the resistance is switched from high to low) is lower than the discharge voltage at the disconnection point of the down conductor 10b.

[0019] In addition, since the down conductor 10b and the conductor 10c form a series circuit via the receptor 10a and the connection part 10d, as shown in FIG. 4, by checking the presence or absence of continuity between the primary side and secondary side of the lightning arrester 11 in the conductor 10c (the primary side is the upstream side and the secondary side is the downstream side with respect to the flow direction of the lightning current I) using a measuring instrument such as a tester 12, it is possible to easily detect breaks in the down conductor 10b and the conductor 10c without working at height or using large-scale equipment.

[0020] FIG. 5 shows an embodiment in which a surge counter 13 is interposed on the secondary side of the lightning arrester 11 in the conductor 10c. As is well known, a surge counter is a device that counts the number of lightning surges that have flowed to the secondary side (ground side) of a lightning protection device such as a lightning arrester. If the surge counter 13 operates when lightning strikes the receptor 10a, it is found that there is a break in the down conductor 10b and the lightning current I has flowed to the conductor 10c. In other words, the operation of the surge counter 13 when lightning strikes the receptor 10a makes it possible to detect the break in the down conductor 10b. This makes it possible to easily detect the break in the down conductor 10b without working at height or using large-scale equipment. [Explanation of symbols]

[0021] 1. Windmill Tower 10 Windmill Blades 10a Receptor 10b Down Conductor 10c conductor 10d Connection 11 Lightning arrester 12 Tester 13 Surge Counter

Claims

1. A down conductor is disposed inside the wind turbine blade and extends along the longitudinal direction of the wind turbine blade; and a conductor is disposed inside the wind turbine blade and extends along the longitudinal direction of the wind turbine blade while being insulated from the down conductor, one end of the down conductor and one end of the conductor are electrically connected to a receptor of the wind turbine blade, respectively; the other end of the down conductor is electrically connected to a ground conductor; a lightning arrester for a wind turbine blade, the other end of the conductor being electrically connected to the other end of the down conductor, and a lightning arrester being interposed on the other end of the conductor.

2. The lightning arrester for a wind turbine blade according to claim 1 , further comprising a surge counter disposed on a secondary side of the lightning arrester in the conductor.

3. A down conductor extending along the longitudinal direction of the wind turbine blade and a conductor extending along the longitudinal direction of the wind turbine blade in a state insulated from the down conductor are disposed inside the wind turbine blade, electrically connecting one end of the down conductor and one end of the conductor to a receptor of the wind turbine blade, respectively; electrically connecting the other end of the down conductor to a ground conductor; The other end of the conductor is electrically connected to the other end of the down conductor, and a lightning arrester is interposed on the other end of the conductor. When there is no break in the down conductor, a lightning current striking the receptor is caused to flow to the ground conductor via the down conductor; When the down conductor is disconnected, a lightning current that strikes the receptor is caused to flow to the ground conductor via the conductor and the lightning arrester.

4. 4. The lightning protection method for a wind turbine blade according to claim 3, further comprising: a surge counter disposed on a secondary side of the lightning arrester in the conductor; and when lightning strikes the receptor, the surge counter is activated to detect a break in the down conductor.

5. The lightning protection method for a wind turbine blade according to claim 3, further comprising the step of detecting a break in the down conductor and the conductor by checking whether or not there is electrical continuity in the conductor between the primary side and the secondary side of the lightning arrester.

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