A lightning protection test method for a heating de-icing blade

Abstract

This invention belongs to the field of new energy wind power generation technology and discloses a lightning protection testing method for heated de-icing wind turbine blades. The method includes conducting a high-voltage test on the blade test specimen to determine the lightning strike point location by observing the breakdown phenomenon; and then conducting a lightning current arc injection test based on the determined lightning strike point location to evaluate the direct effect damage to the blade test specimen surface. By simulating the real lightning environment of the heated de-icing wind turbine blade test specimen, a high-voltage test is first conducted to determine the lightning strike point location; then, a lightning current arc injection test is conducted based on the lightning strike point location determined by the high-voltage test to evaluate the direct effect damage to the blade surface. This method can effectively test the lightning protection performance of blades and solves the problem that traditional blade lightning testing methods cannot evaluate the lightning protection performance of heated de-icing wind turbines.

Description

Technical Field

[0001] This invention belongs to the field of new energy wind power generation technology, specifically relating to a lightning protection test method for heated de-icing blades. Background Technology

[0002] In low-wind-speed areas and some high-wind-speed areas, wind farms commonly experience winter freezing problems. According to statistics, 54% of unit shutdowns are caused by icing. When blades are iced, their aerodynamic performance is affected. On the one hand, this can lead to blade overload and uneven blade load distribution, which in turn significantly affects the continuous wind energy output. On the other hand, during the rotation of the blades, ice blocks are very likely to fall off, causing operational accidents.

[0003] Ice formation on the blades increases the load and directly affects their lifespan. The ice load varies on each blade, increasing the unbalanced load on the unit. If no timely countermeasures are taken, it can cause serious damage to the unit. Wind turbine blades without anti-icing and de-icing protection may face grid disconnection and shutdown. Low-temperature areas significantly reduce the overall annual power generation, with an annual power generation loss of 1%-10%, and close to 20%-50% in severe areas.

[0004] While electrothermal materials such as carbon fiber fabric, carbon-glass hybrid fiber fabric, carbon fiber felt, graphene, carbon nanotubes, and epoxy resin-conductive carbon black can effectively remove ice from blade surfaces, these materials increase the risk of lightning strikes. Therefore, conducting lightning protection tests on blade specimens containing electrothermal materials to evaluate their lightning protection performance is a problem that needs to be solved. Existing lightning protection testing techniques cannot assess direct-effect damage to the surface of the blade specimens. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a lightning protection test method for heated de-icing blades. This method simulates the real lightning environment of the heated de-icing wind turbine blade test piece. First, a high-voltage test is conducted to determine the location of the lightning strike attachment point. Then, based on the lightning strike attachment point location determined by the high-voltage test, a lightning current arc injection test is conducted to evaluate the direct effect damage to the surface of the electrically heated de-icing blade.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for testing the lightning protection of heated de-icing blades includes:

[0008] High-voltage tests were conducted on the blade test specimens to determine the location of the lightning attachment point by observing the breakdown phenomenon.

[0009] Based on the determined location of the lightning strike attachment point, a lightning current arc injection test was conducted to evaluate the direct effect damage on the surface of the electric blade test specimen.

[0010] As a further improvement of the present invention, the high-voltage test includes:

[0011] The blade test specimen is suspended with an insulated rope so that the trailing edge of the blade test specimen is aligned with the grounding plate. The height of the blade test specimen from the grounding plate is measured until the distance between the lowest point of the blade test specimen and the grounding plate and the distance between the lowest lightning arrester of the blade test specimen and the grounding plate meet the height requirements.

[0012] The inclination angle between the blade test specimen and the ground is adjusted using an insulated sling; an electric heating film is attached to the trailing edge of the blade test specimen, and the power supply line of the electric heating film is connected to the heating power source.

[0013] The high voltage generator produces a voltage waveform. The high voltage generator is connected to the voltage divider. The voltage of the voltage divider is connected to the heating power supply and the lightning protection down conductor of the blade test piece through the high voltage terminal cable of the power supply and the high voltage terminal cable of the down conductor, respectively.

[0014] Turn on the power and charge the voltage divider until a breakdown occurs between the voltage and the grounding plate. Mark the location of the lightning attachment point on the blade test specimen.

[0015] As a further improvement of the present invention, the high voltage generator produces a double exponential impulse voltage waveform with a voltage waveform of 250μs to 2500μs.

[0016] As a further improvement of the present invention, the grounding plate is a metal aluminum plate or a metal copper plate, and the area of ​​the grounding plate is more than twice the projected area of ​​the blade test piece.

[0017] As a further improvement of the present invention, before the power is turned on and the voltage divider is charged, the following is also included:

[0018] During the initial pilot attachment test, the applied voltage should rise to the point where flashover occurs before the peak of the voltage waveform; the time interval between the start of the voltage waveform and the structural flashover should be at least 50 μs.

[0019] As a further improvement of the present invention, when the high voltage test is carried out, the tilt angle between the blade test piece and the ground is measured to be 10° to 60°, and the corresponding attitudes are leading edge facing the ground, trailing edge facing the ground, windward facing the ground and leeward facing the ground, respectively, with positive polarity and negative polarity, respectively; each test condition is repeated multiple times.

[0020] As a further improvement of the present invention, the lightning current arc injection test includes:

[0021] Representative lightning attachment points were selected to introduce lightning current; under the power supply of the electric heating film, the lightning current was applied to the surface of the blade test specimen through the impulse current generator to evaluate whether the de-icing blade test specimen could work normally.

[0022] As a further improvement of the present invention, in the lightning current arc injection test, the heating power supply is connected to the first floor through the first grounding cable; the lightning protection down conductor is connected to the second floor through the second grounding cable.

[0023] As a further improvement of the present invention, the lightning current arc injection test injects a lightning current of 200kA and 10MJ~Ω.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] This invention simulates the real lightning environment of a heated de-icing wind turbine blade test specimen. First, a high-voltage test is conducted to determine the location of the lightning strike point. Then, based on the lightning strike point location determined by the high-voltage test, a lightning current arc injection test is performed to evaluate the direct effect damage to the surface of the blade test specimen. This method can effectively test the lightning protection performance of blade test specimens, solving the problem that traditional lightning testing methods for blade test specimens cannot evaluate the lightning protection performance of heated de-icing wind turbines. Attached Figure Description

[0026] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely illustrative to aid in understanding the invention and do not specifically limit the shapes and proportions of the components of the invention.

[0027] Figure 1 This is a connection diagram of the high-voltage test apparatus provided in an embodiment of the present invention;

[0028] Figure 2 A connection diagram of the lightning current arc injection test device provided in an embodiment of the present invention;

[0029] In the attached diagram:

[0030] 1—High voltage generator, 2—Voltage divider, 3—Power supply high voltage end cable, 4—Down lead high voltage end cable, 5—Heating power supply, 6—Electric heating film, 7—Blade test piece, 8—Grounding plate, 9—Impulse current generator, 10—Measuring system, 11—Insulating bracket, 12—First grounding cable, 13—Second grounding cable, 14—First grounding plate, 15—Second grounding plate. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0032] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0034] Since the blade heating material is usually electrically charged and the power supply is ultimately connected to the ground, the traditional high-voltage blade test method cannot be used to evaluate the lightning adhesion characteristics of the blade.

[0035] This invention provides a high-voltage testing method for electrically heated de-icing blades, comprising the following steps:

[0036] A high-voltage test was conducted on blade test specimen 7, and the location of the lightning attachment point was determined by the occurrence of breakdown phenomenon.

[0037] Based on the determined location of the lightning strike attachment point, a lightning current arc injection test was conducted to evaluate the direct effect damage on the surface of the electric blade test piece 7.

[0038] The high-voltage test of the present invention specifically includes:

[0039] Use an insulated rope to suspend the blade test piece 7 so that the trailing edge of the blade test piece 7 is aligned with the grounding plate 8. Measure the height of the blade test piece 7 from the grounding plate 8 until the distance between the lowest point of the blade test piece 7 and the grounding plate 8 and the distance between the lowest lightning rod of the blade test piece 7 and the grounding plate 8 meet the height requirements.

[0040] The inclination angle between the measuring blade test piece 7 and the grounding plate 8 is adjusted using an insulating sling; an electric heating film 6 is attached to the rear edge of the blade test piece 7, and the power supply line of the electric heating film 6 is connected to the heating power supply 5;

[0041] High voltage generator 1 generates a voltage waveform. High voltage generator 1 is connected to voltage divider 2. The voltage of voltage divider 2 is connected to heating power supply 5 and lightning protection down conductor of blade test piece 7 through power supply high voltage terminal cable 3 and down conductor high voltage terminal cable 4 respectively.

[0042] Turn on the power and charge the voltage divider 2 until a breakdown occurs between the voltage and the grounding plate 8. Mark the location of the lightning attachment point on the blade test piece 7.

[0043] like Figure 1 As shown, the specific experimental setup is connected as follows: the high-voltage generator 1 is electrically connected to the voltage divider 2 to provide high voltage to the blade test piece 7; the blade test piece 7 is suspended by an insulated rope, with its tip tilted downwards; an electric heating film 6 and a heating power supply 5 are provided on the surface of the blade test piece 7, and the electric heating film 6 and the heating power supply 5 are electrically connected; the voltage divider 2 is connected to the heating power supply 5 and the lightning protection down conductor of the blade test piece 7 respectively through the high-voltage power supply cable 3 and the high-voltage down conductor cable 4.

[0044] As an optional solution, the high voltage generator 1 of the present invention generates a double exponential impulse voltage waveform with a voltage waveform of 250μs to 2500μs.

[0045] In the above embodiment, before the voltage divider 2 is charged after the power is turned on, the following steps are also included:

[0046] During the initial pilot attachment test, the applied voltage should rise to the point where flashover occurs before the peak of the voltage waveform; the time interval between the start of the voltage waveform and the structural flashover should be at least 50 μs.

[0047] To ensure more accurate and realistic test results, during the high-voltage test, the tilt angle between the blade test piece 7 and the grounding plate 8 is measured to be 10° to 60°, corresponding to the leading edge facing the ground, trailing edge facing the ground, windward facing the ground, and leeward facing the ground, with positive and negative polarities, respectively; each test condition is repeated multiple times.

[0048] The lightning current arc injection test of the present invention includes:

[0049] A representative lightning attachment point is selected to introduce lightning current; under the power supply condition of the electric heating film 6, the lightning current is applied to the surface of the blade test piece 7 through the impulse current generator 9 to evaluate whether the de-icing blade test piece 7 can work normally.

[0050] like Figure 2As shown, in the lightning current arc injection test, the impulse current generator 9 and the measurement system 10 are electrically connected, and the input terminal of the impulse current generator 99 is connected to the electric heating film 6. The heating power supply 5 is connected to the first floor 14 through the first grounding cable 12; the lightning protection down conductor is connected to the second floor 15 through the second grounding cable 13.

[0051] In the above embodiments, the lightning current arc injection test injects a lightning current of 200kA and 10MJ~Ω.

[0052] The present invention will be described in detail below with reference to specific embodiments.

[0053] Example 1

[0054] like Figure 1 As shown, the lightning protection test method for heated de-icing blades includes the following specific steps:

[0055] The blade test specimen 7 is suspended in the air, with its lowest point more than 1.5 meters above the ground plate, and simultaneously, the distance between the blade test specimen 7 and the ground is more than 2 meters. The lightning protection down conductor and the ground wire of the heating power supply 5 of the blade test specimen 7 are simultaneously connected to the high-voltage end. The heating power supply 5 heats the electric heating film 6 through the power supply line. The high-voltage test of the blade test specimen 7 must be conducted under heating and power supply conditions. Connecting the down conductor and the power supply line to the high-voltage end simultaneously simulates the lightning strike conditions of the blade test specimen 7 under actual operating conditions.

[0056] During the high-voltage test of the heated de-icing blades, a double-exponential impulse voltage waveform of 250μs to 2500μs is used. During the initial leader attachment test, the applied voltage should rise to the point of flashover before the peak of the voltage waveform. The time interval between the start of the voltage waveform and the structural flashover should be at least 50μs.

[0057] During the tests, the blade tip angles to the ground were 10°, 30°, and 60°, with the blades facing the ground at the leading edge, trailing edge, windward, and leeward, respectively, and the polarities being positive and negative. Each test condition was repeated three times, for a total of 72 high-voltage tests. The locations of lightning strike points were determined based on the test results.

[0058] like Figure 2As shown, based on the lightning attachment point location results, representative lightning attachment point locations are selected for lightning current arc injection tests. The lightning current arc injection test injects a lightning current of 200kA, 10MJ~Ω into the selected lightning attachment point. The lightning current test needs to be conducted under the power supply conditions of the electric heating film 6. The lightning current for the test is applied to the surface of the blade test piece 7 through the impulse current generator 9. The lightning current test lead and the power supply are connected to the first ground plate 14 and the second ground plate 15, respectively, and the first ground plate 14 and the second ground plate 15 are connected at a remote end. During the current test, the impact on the heating system is assessed. After the test, the normal operation of the de-icing blade test piece 7 and the heating system is evaluated.

[0059] Example 2:

[0060] This embodiment further illustrates the high-voltage test of the present invention.

[0061] like Figure 1 As shown, taking the trailing edge of the electric blade test piece 7 as an example, with the angle between the blade test piece 7 and the opposite side being 30°, the blade test piece 7 is suspended using an insulated rope, so that the trailing edge of the blade test piece 7 is aligned with the grounding plate 8. The height of the blade test piece 7 from the grounding plate 8 is measured until the height of the lowest point of the blade test piece 7 above the grounding plate 8 is greater than 1.5 meters, and the height of the lowest lightning arrester of the blade test piece 7 from the grounding plate 8 is greater than 2 meters. Simultaneously, the angle between the blade test piece 7 and the grounding plate 8 is adjusted using an insulated sling to ensure that the angle is 30°. The grounding plate 8 is a metal aluminum plate or a metal copper plate, and its size must be at least twice the size of the blade test piece 7. An electric heating film 6 is attached to the trailing edge of the blade test piece 7, and the power supply line of the electric heating film 6 is connected to the heating power supply 5. High voltage generator 1 generates a voltage waveform of 250μs to 2500μs. High voltage generator 1 is connected to voltage divider 2. The voltage of voltage divider 2 is connected to heating power supply 5 and lightning protection down conductor through power supply high voltage terminal cable 3 and down conductor high voltage terminal cable 4, respectively, to evaluate the possible flashover points of the blade test specimen 7 lightning protection system and electric heating de-icing system.

[0062] Turn on the power and charge voltage divider 2. Continue until a breakdown occurs between the voltage and ground, then mark the lightning attachment point on blade test specimen 7.

[0063] Unless otherwise specified, the equipment components involved in the above embodiments are all conventional equipment components, and the structural settings, working methods or control methods involved are all conventional settings, working methods or control methods in the art unless otherwise specified.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A lightning test method for a heating de-icing blade, characterized by, include: A high-voltage test was conducted on the blade test specimen (7) to determine the location of the lightning attachment point by the occurrence of breakdown phenomenon; Based on the determined location of the lightning strike attachment point, a lightning current arc injection test was conducted to evaluate the direct effect damage on the surface of the electric blade test piece (7). The high-voltage test includes: The blade test piece (7) is lifted with an insulated rope so that the trailing edge of the blade test piece (7) is aligned with the grounding plate (8). The height of the blade test piece (7) from the grounding plate (8) is measured until the distance between the lowest point of the blade test piece (7) and the grounding plate (8) and the distance between the lowest lightning rod of the blade test piece (7) and the grounding plate (8) meet the height requirements. The inclination angle between the measuring blade test piece (7) and the grounding plate (8) is adjusted using an insulating sling; an electric heating film (6) is attached to the rear edge of the blade test piece (7), and the power supply line of the electric heating film (6) is connected to the heating power supply (5). The high voltage generator (1) generates a voltage waveform. The high voltage generator (1) is connected to the voltage divider (2). The voltage of the voltage divider (2) is connected to the heating power supply (5) and the lightning protection down conductor of the blade test piece (7) through the power supply high voltage end cable (3) and the down conductor high voltage end cable (4), respectively. Turn on the power supply and charge the voltage divider (2); until a breakdown occurs between the voltage and the ground plate (8), mark the location of the lightning attachment point on the blade test piece (7).

2. The lightning test method for a heating de-icing blade according to claim 1, wherein The high voltage generator (1) generates a double exponential impulse voltage waveform with a voltage waveform of 250μs~2500μs.

3. The lightning test method for a de-icing blade according to claim 1, wherein The grounding plate (8) is a metal aluminum plate or a metal copper plate, and the area of ​​the grounding plate (8) is more than twice the projected area of ​​the blade test piece (7).

4. The lightning test method for a de-icing blade according to claim 1, wherein Before the power is turned on and the voltage divider (2) is charged, the following steps are also included: During the initial pilot attachment test, the applied voltage should rise to the point where flashover occurs before the peak of the voltage waveform; the time interval between the start of the voltage waveform and the structural flashover should be at least 50 μs.

5. The lightning protection test method for a de-icing blade according to claim 1, wherein When the high voltage test is carried out, the tilt angle between the blade test piece (7) and the grounding plate (8) is measured to be 10°~60°, and the corresponding attitudes are leading edge to ground, trailing edge to ground, windward face to ground and leeward face to ground, respectively, with positive polarity and negative polarity, respectively; each test condition is repeated multiple times.

6. The lightning protection test method for a de-icing blade according to claim 1, wherein The lightning current arc injection test includes: Select representative lightning attachment points to introduce lightning current; under the power supply of the electric heating film (6), the lightning current is applied to the surface of the blade test piece (7) through the impulse current generator (9) to evaluate whether the de-icing blade test piece (7) can work normally.

7. The lightning protection test method for a de-icing blade according to claim 6, wherein In the lightning current arc injection test, the heating power supply (5) is connected to the first floor (14) through the first grounding cable (12); the lightning protection down conductor is connected to the second floor (15) through the second grounding cable (13).

8. The lightning protection test method for heated de-icing blades according to claim 6, characterized in that, The lightning current arc injection test injects a lightning current of 200kA and 10MJ~Ω.

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