Offshore wind turbine blade anti-bursting device based on field grinding electric field sensor

Abstract

The invention discloses an offshore wind turbine blade lightning stroke anti-bursting device based on a field friction electric field sensor, and relates to the field of lightning protection. The offshore wind turbine blade lightning stroke anti-bursting device based on the electromagnetic induction principle is composed of a wind power field-containing electric field sensor, a control circuit and a valve device. The wind power field friction electric field sensor comprises a shielding layer, a sensing layer, a power device, a shell, a first connecting joint, a second connecting joint, a cleaning scraper and a supporting column. The wind power field friction electric field sensor predicts thunder and lightning and is matched with a control circuit to open a valve device in advance. The control circuit consists of an operational amplifier, a comparator, a transistor, a normally open relay and a power supply I; the valve device is composed of an electromagnetic valve, an auxiliary channel, a second power source and a filtering cover, and the offshore wind turbine blade lightning stroke anti-burst device based on the field-grinding electric field sensor can effectively prevent gas burst of the wind turbine blade during lightning stroke.

Description

Technical Field

[0001] The present invention relates to the field of protection for new energy devices, and more specifically, to a lightning strike explosion-proof device for offshore wind turbine blades based on a field mill electric field sensor. Background Art

[0002] Wind power generation has become the most technically mature, most scalable for development, and commercially promising renewable energy power generation method in the world. Vigorously developing wind power is of great strategic significance in aspects such as energy security, diversified energy supply, response to climate change, and energy conservation and emission reduction. In terms of installed power generation capacity, in the past three years, the overall installed power generation capacity of wind power in the country has shown an upward trend. From January to October 2024, the installed power generation capacity of wind power in the country was 486.17 million kilowatts, a year-on-year increase of 20.3%. In terms of newly added installed power generation capacity, the newly added installed power generation capacity of wind power in the country has increased as a whole in the past three years. From January to October 2024, the newly added installed power generation capacity of wind power in the country was 45.8 million kilowatts, a year-on-year increase of 849%.

[0003] Currently, the lightning strike protection of wind turbine blades mainly relies on the lightning arrester downlead system, which is composed of tip and blade body lightning arresters connected to the grounding wire arranged inside the blade cavity. When a lightning strike occurs, the tip and blade body lightning arresters initiate upward leaders to intercept the downward leader of the lightning. After the connection of the upward and downward leaders, the lightning current energy is discharged to the ground through the downlead, thereby protecting the blade and even the entire unit from lightning damage.

[0004] The discharge temperature of lightning is extremely high, usually between 20,000°C and 30,000°C, much higher than the melting point and boiling point of ordinary materials. At the moment of lightning strike, the current passes through the blade while heating the surface of the blade and the surrounding air. When lightning discharges, the instantaneously generated high temperature will rapidly heat the surrounding air and cause the air to expand sharply. During the air expansion process, very high pressures may be generated, especially if there are cavities inside the blade (such as foam, filling materials, or micro-cavities inside the wind turbine blade). If there are sealed or semi-sealed cavities inside the blade, heat can be transferred to the air through the conduction path of the current flowing through the blade and rapidly heat the air. This heating will cause the air to expand rapidly, increasing the internal gas pressure in a short time. If the cavity has good sealing and the pressure accumulates to a certain extent, gas explosion may occur.

[0005] Aiming at the deficiencies of the current lightning strike explosion-proof and protection technology for offshore wind turbine blades, the present invention proposes a lightning strike explosion-proof device for offshore wind turbine blades based on a field mill electric field sensor. It can predict lightning before the lightning strike and open the valve device, and close the valve device after the lightning strike is completed, which can effectively adjust the air pressure on both sides of the blade and effectively protect the blade from gas explosion caused by lightning strikes. Summary of the Invention

[0006] The object of the present invention is to provide a lightning strike explosion-proof device for an offshore wind turbine blade based on a field mill electric field sensor. It can predict lightning before the lightning strike occurs, open the valve device, and close the valve device after the lightning strike is completed, effectively regulating the air pressure on both sides of the blade and effectively protecting the blade from gas explosion caused by lightning strikes.

[0007] To achieve the above object, the technical solution of the present invention is:

[0008] A lightning strike explosion-proof device for an offshore wind turbine blade based on a field mill electric field sensor, which is composed of a wind power field mill electric field sensor, a control circuit and a valve device;

[0009] The wind power field mill electric field sensor includes a shielding layer, an induction layer, a power device, a housing, a connecting joint one, a connecting joint two, a cleaning blade and a support column. It predicts lightning and is connected to the control device to open the valve device in advance. The wind power field mill electric field sensor is placed on the top of the wind turbine hub. The shielding layer, the power device and the cleaning blade are of an integral structure. Preferably, the shielding layer, the power device and the cleaning blade are made of conductive plastic with light weight, easy processing and certain hardness. The housing, the connecting joint one, the connecting joint two and the support column are of an integral structure. The housing and the support column should have mechanical strength, corrosion resistance and electrical insulation, and preferably a plastic housing (such as ABS, polycarbonate) is used. The shielding layer and the support column are connected together through the connecting joint one. The connecting joint one is at the top of the support column and has the functions of supporting and fixing the shielding layer, the power device and the cleaning blade. The induction layer is fixed on the support column through the connecting joint two. Preferably, the induction metal sheet is made of copper or aluminum material, which not only has good electrical conductivity but also helps to quickly sense the change of the electric field. Preferably, the surface area of the induction metal sheet is 100 cm 2On the left and right, the shape of the induction metal sheet is a disc, parallel to the horizontal plane; under the thundercloud, the induction layer induces an electric current (the induced current is generally very small), which, after being processed by the I / V conversion circuit, the amplification and band-pass filter circuit, outputs a sine signal with a single frequency, and then forms a smooth pulsating signal after rectification and filtering; according to the amplitude of the induction signal and the required relay control voltage, the gain is set by adjusting the feedback resistance of the operational amplifier. To avoid the relay being triggered under each small electric field fluctuation, a threshold voltage is set by the comparator, and the relay is triggered only when the voltage exceeds this threshold. An NPN transistor is used as a switch. The output of the comparator is connected to the base of the transistor, and the on-off of the transistor is controlled through an appropriate current-limiting resistor. The collector of the transistor is connected to one end of the relay, and the other end is connected to the power supply. When the transistor conducts, the relay is attracted. The relay power supply is usually independent of the signal circuit, and an appropriate power supply (such as 5V, 12V or 24V) is required to provide sufficient current. The connecting joint two is placed in the middle of the support column, which has the function of supporting and fixing the induction layer; the shielding layer is parallel to the induction layer, and three round holes are opened around the center; the power device consists of three blades, each blade is connected to the shielding layer, and the upper and lower sides of the blade are fixed by rings to prevent the blade from breaking due to uneven force; the cleaning blade is connected to the shielding layer through a cylinder, and the inner diameter of the cylinder is the same as the diameter of the support column, and the length of the cylinder enables the bottom surface of the cleaning blade to contact the induction layer; the cleaning blade rotates together with the shielding layer and the power device to remove attachments such as salt on the surface of the induction layer;

[0010] The control circuit consists of an I / V conversion circuit, an operational amplifier, a rectification and filtering circuit, a comparator, a transistor, a normally open relay and a power supply one; after being packaged, the control circuit is placed inside the wind turbine hub; the control device controls the operation of the valve device through the opening and closing of the normally open relay; one end of it is the wind field grinding electric field sensor, and the other end is connected to the valve device; when the wind field grinding electric field sensor senses an electric signal, the control device acts, and the series circuit of the power supply two and the solenoid valve is turned on to open the valve device; preferably, the normally open relay selects relays with voltage levels such as 5V, 12V, 24V, etc.;

[0011] The valve device consists of a solenoid valve, a sub-channel, a power supply two and a filter cover. One end of it is connected to the control circuit. When the wind field grinding electric field sensor and the control circuit are started, the series circuit of the power supply two and the solenoid valve is turned on, and the solenoid valve opens; the sub-channel is used to balance the air pressure inside and outside the blade cavity after a lightning strike; the power supply two is used to provide electrical energy for the solenoid valve; the filter cover has the function of filtering external moisture and salt; the valve device is distributed on the leeward side of the blade and is densely arranged at positions adjacent to the lightning arrester; it is sparsely arranged at positions far from the lightning arrester;

[0012] The filter covers are distributed at the notch of the concave-shaped housing, and one side is aligned with the outer skin on the leeward side of the fan; the filter covers have the function of filtering external moisture and salts, preventing external moisture and salt spray from entering the blade cavity; the inner surface of the filter covers is filled with materials such as polyvinyl alcohol, polyurethane, calcium chloride, and magnesium chloride, which have strong hygroscopicity and can absorb moisture and salt spray in the air;

[0013] The auxiliary channel is used to balance the air pressure inside and outside the blade cavity after lightning strikes; the auxiliary channel is distributed at the sunken wall at the notch of the concave-shaped housing, connecting the inner cavity of the fan blade and the notch of the concave-shaped housing; low-quality and low-density balls are placed inside the auxiliary channel. When the internal and external air pressures are balanced, the balls block the auxiliary channel. When the external air pressure is greater than the internal air pressure, the external gas bounces the balls to connect the internal and external spaces, thereby balancing the air pressure inside and outside the blade cavity after lightning strikes; multiple auxiliary channels are distributed around the sunken wall at the notch of the concave-shaped housing, connecting the inner cavity of the fan blade and the notch of the concave-shaped housing; the inlet and outlet of the auxiliary channel are circular, and the diameter is smaller than the diameter of the balls; the inner wall of the auxiliary channel is inclined to ensure that the bounced balls can block the inlet of the auxiliary channel after the air pressure inside and outside the blade cavity is balanced. There should be a baffle at the outlet of the auxiliary channel to prevent the bounced balls from flying out of the auxiliary channel;

[0014] The electromagnetic valve consists of an electromagnetic chuck, a metal disc, a concave-shaped housing, a spring, a rubber patch, and an external power supply; after the control device is started, the external power supply is connected to the electromagnetic chuck circuit; at this time, the electromagnetic chuck generates magnetic force to attract the metal disc, and the metal disc separates from the concave-shaped housing, and the internal and external spaces of the blade are connected; the spring connects the metal disc and the concave-shaped housing; in the normal closed state, the spring is in a stretched state to ensure that the spring connects the metal disc and the concave-shaped housing to fit tightly; rubber patches are respectively placed at the joint of the metal disc and the concave-shaped housing to ensure that the metal disc and the concave-shaped housing fit tightly and play a buffering role when opening and closing;

[0015] The beneficial effects of the present invention: The discharge temperature of lightning is extremely high, usually between 20,000 °C and 30,000 °C, much higher than the melting point and boiling point of ordinary materials. At the moment of lightning strike, the current passes through the blade and heats the surface of the blade and the surrounding air at the same time. This heating will cause the air to expand rapidly and increase the internal gas pressure in a short time. If the cavity has good sealing and the pressure accumulates to a certain extent, it may lead to gas explosion. Few people have a lightning strike explosion-proof device for offshore wind turbine blades to reduce or avoid blade damage caused by gas explosion. The present invention provides a solution to the above problems, providing a lightning strike explosion-proof device for offshore wind turbine blades based on a field mill electric field sensor, which can effectively adjust the air pressure inside and outside the blade cavity by predicting lightning before the lightning strike and opening the valve device, and closing the valve device after the lightning strike is completed, and can effectively protect the blade from gas explosion caused by lightning strikes. Description of the Drawings

[0016] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts belong to the scope of protection of the present application.

[0017] Figure 1 Structural diagram of the wind field mill electric field sensor of the lightning strike explosion-proof device for the blade of an offshore wind turbine based on the field mill electric field sensor of the present invention;

[0018] Figure 2 Schematic diagram of the control circuit of the lightning strike explosion-proof device for the blade of an offshore wind turbine based on the field mill electric field sensor of the present invention;

[0019] Figure 3 Structural diagram of the valve device of the lightning strike explosion-proof device for the blade of an offshore wind turbine based on the field mill electric field sensor of the present invention;

[0020] Figure 4 Structural diagram of the first connecting joint of the lightning strike explosion-proof device for the blade of an offshore wind turbine based on the field mill electric field sensor of the present invention;

[0021] Figure 5 Structural diagram of the second connecting joint of the lightning strike explosion-proof device for the blade of an offshore wind turbine based on the field mill electric field sensor of the present invention;

[0022] Figure 6 Structural diagram of the secondary channel of a lightning strike explosion-proof device for the blade of an offshore wind turbine of the present invention; Explanation of reference numerals:

[0023] Wind field mill electric field sensor (1), shielding layer (101), round hole (1011), induction layer (102), power device (103), blade (1031), ring (1032), housing (104), first connecting joint (105), second connecting joint (106), cleaning blade (107), cylinder (1071), support column (108); control circuit (2), conversion circuit (201), operational amplifier (202), rectification and filtering circuit (203), comparator (204), transistor (205), normally open relay (206) and power supply one (207); valve device (3), solenoid valve (301), electromagnetic chuck (3011), metal disc (3012), concave housing (3013), spring (3014), rubber patch (3015); secondary channel (302), small ball (3021), secondary channel inlet (3022), secondary channel outlet (3023), secondary channel inner wall (3024); power supply two (303), filter cover (304); Detailed implementation mode

[0024] The present invention will be further described below in conjunction with the accompanying drawings and embodiments; the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present application.

[0025] The purpose of the present invention is to provide a lightning strike explosion-proof device for an offshore wind turbine blade based on a field mill electric field sensor, which predicts lightning before the lightning strike and opens the valve device (3), and closes the valve device (3) after the lightning strike is completed; it can effectively adjust the air pressure inside and outside the blade cavity and effectively protect the blade gas explosion caused by lightning strikes.

[0026] To achieve the above purpose, the technical solution of the present invention is as follows:

[0027] First, in combination with Figure 1 、 Figure 2 and Figure 3 An offshore wind turbine blade lightning strike explosion-proof device provided by an embodiment of the present application is introduced. An offshore wind turbine blade lightning strike explosion-proof device based on a field mill electric field sensor, characterized in that it includes a wind field mill electric field sensor (1), a control circuit (2) and a valve device (3); when an offshore thunderstorm occurs, the probability of wind is very high, close to 100%. Almost all offshore thunderstorms are accompanied by strong winds, and the wind speed can be very high. During the approach and discharge process of the thundercloud, the thundercloud electric field The electric flux passing through the area S of any induction layer (102) is equal to the algebraic sum of the free charges enclosed within the curved surface Divided by the permittivity ε0, that is

[0028] A periodic induced current i(t) is generated on the induction sheet of the field mill type electric field sensor, and the amplitude of the induced current has a linear relationship with the measured electric field: A(t) is the total area of the induction sheet exposed to the measured electric field; ε0 is the air permittivity; Is the measured electric field strength.

[0029] After the induced current is processed by the I / V conversion circuit (201), the operational amplifier (202), and the amplification and band-pass filter circuit, a sine signal of a single frequency is output, and then a smooth pulsating signal is formed after passing through the rectification and filter circuit (203); the voltage is controlled according to the amplitude of the induced signal and the transistor (205) used, and the gain is set by adjusting the feedback resistance of the operational amplifier (202). To avoid the normally open relay (206) being triggered by each small electric field fluctuation, a threshold voltage is set by the comparator (204), and the normally open relay (206) is triggered only when the voltage exceeds this threshold. The output of the comparator (204) is connected to the base of the transistor (205), and the switching of the transistor (205) is controlled through an appropriate current-limiting resistor. The collector of the transistor (205) is connected to one end of the normally open relay (206), and the other end is connected to the power supply one (207). When the transistor (205) is turned on, the normally open relay (206) closes. The solenoid valve (301) of the valve device (3) is turned on with the loop of the power supply two (303), and the electromagnetic chuck (3011) attracts the metal disc (3012) and the valve device (3) opens; after the lightning strike ends, the electric field around the induction layer (102) is zero, the current induced in the changing electric field is zero, the normally open relay (206) opens, and under the action of the spring, the electromagnetic chuck (3011) and the metal disc (3012) are separated, and the valve device (3) closes.

[0030] Figure 3 As shown in the figure, it is the structural diagram of the exhaust device (3) of the lightning strike explosion-proof device for the blade of the offshore wind turbine based on the field mill electric field sensor of the present invention; the exhaust device (3) is distributed on the leeward side of the blade and is densely arranged at a position adjacent to the lightning arrester; it is sparsely arranged at a position far from the lightning arrester; the valve device (3) is composed of a solenoid valve (301), a sub-channel (302), a power supply two (303), and a filter cover (304), and one end of it is connected to the control circuit (2). When the wind field mill electric field sensor (1) and the control circuit (2) are started, the series loop of the power supply two (303) and the solenoid valve (301) is turned on, and the solenoid valve (301) opens; the function of the sub-channel (302) is to balance the air pressure inside and outside the blade cavity after the lightning strike; the function of the power supply two (303) is to provide electric energy for the solenoid valve (301); the filter cover (304) has the function of filtering external moisture and salt; Figure 3 As shown in the figure, the spring (3014) connects the metal disc (3012) and the concave housing (3013); in the normal closed state, the spring (3014) is in a stretched state to ensure that the metal disc (3012) and the concave housing (3013) are closely attached; the rubber patches (3015) are respectively placed at the joint of the metal disc (3012) and the concave housing (3013) to ensure that the metal disc (3012) and the concave housing (3013) are closely attached and play a buffering role when opening and closing;

[0031] As Figure 4 shown, the connecting joint one (105) is at the top of the support column (108), and has the functions of supporting and fixing the shielding layer (101), the power device (103) and the cleaning wiper (107); As Figure 5 shown, the induction layer (102) is fixed on the support column (108) through the connecting joint two (106); The connecting joint two (106) is placed in the middle of the support column (108), and has the function of supporting and fixing the induction layer (102);

[0032] As Figure 6 shown, small balls (3021) with low mass and low density are placed inside the secondary channel (302). When the internal and external air pressures are balanced, the small balls (3021) block the secondary channel (302). When the external air pressure is greater than the internal air pressure, the external gas bounces the small balls (3021) to connect the internal and external spaces, so as to balance the air pressure inside and outside the blade after lightning strike; A plurality of secondary channels (302) are distributed around the recessed wall (4016) at the notch of the concave outer shell (4013), connecting the inner cavity of the fan blade and the notch of the concave outer shell (3013); The secondary channel inlet (3022) and the secondary channel outlet (3023) are circular, and the diameter is smaller than the diameter of the small balls (3021); The inner wall (3024) of the secondary channel is inclined to ensure that the small balls (3021) bounced off after the air pressure inside and outside the blade cavity is balanced can block the secondary channel inlet (3022), and there should be a baffle at the secondary channel outlet (3023) to prevent the bounced small balls (3021) from flying out of the secondary channel (302).

Claims

1. A lightning strike explosion-proof cracking device for an offshore wind turbine blade based on a field mill electric field sensor, characterized in that: It includes a wind field and mill electric field sensor (1), a control circuit (2), and a valve device (3); The wind field and mill electric field sensor (1) consists of a shielding layer (101), an induction layer (102), a power device (103), a housing (104), a connecting joint one (105), a connecting joint two (106), a cleaning blade (107), and a support column (108). It predicts lightning and is connected to the control device (2) to open the valve device (3) in advance. The wind field and mill electric field sensor (1) is placed on top of the fan hub. The shielding layer (101), the power device (103), and the cleaning blade (107) are of an integral structure. The housing (104), the connecting joint one (105), the connecting joint two (106), and the support column (108) are of an integral structure. The shielding layer (101) and the support column (108) are combined together through the connecting joint one (105). The connecting joint one (105) is at the top of the support column (108) and functions to support and fix the shielding layer (101), the power device (103), and the cleaning blade (107). The induction layer (102) is fixed to the support column (108) through the connecting joint two (106). The connecting joint two (106) is placed at the middle position of the support column (108) and functions to support and fix the induction layer (102). The shielding layer (101) is parallel to the induction layer (102) and has three circular holes (1011) opened around the center. The power device (103) consists of three blades (1031). Each blade (1031) is connected to the shielding layer (101), and both the upper and lower sides of the blade are fixed by a ring (1032) to prevent the blade (1031) from breaking due to uneven force. The cleaning blade (107) is connected to the shielding layer (101) through a cylinder (1071). The inner diameter of the cylinder (1071) is the same as the diameter of the support column (108), and the length of the cylinder (1071) enables the bottom surface of the cleaning blade (107) to contact the induction layer (102). The cleaning blade (107) rotates together with the shielding layer (101) and the power device (103) to remove attachments such as salt on the surface of the induction layer (102); The control circuit (2) consists of an I / V conversion circuit (201), an operational amplifier (202), a rectification and filtering circuit (203), a comparator (204), a transistor (205), a normally open relay (206), and a power supply one (207). The control circuit (2) is packaged and placed inside the fan hub. The control device (2) controls the operation of the valve device (3) through the opening and closing of the normally open relay (204). One end of it is connected to the wind field and mill electric field sensor (1), and the other end is connected to the valve device (3). When the wind field and mill electric field sensor (1) senses an electrical signal, the control device (2) acts, and the series circuit of the power supply two (303) and the solenoid valve (301) is turned on to open the valve device (3); The valve device (3) is composed of an electromagnetic valve (301), a secondary channel (302), a second power source (303), and a filter cover (304). One end of the valve device is connected to the control circuit (2). When the wind field mill electric field sensor (1) and the control circuit (2) are activated, the series circuit of the second power source (303) and the electromagnetic valve (301) is turned on, and the electromagnetic valve (301) opens. The secondary channel (302) is used to balance the air pressure inside and outside the blade cavity after a lightning strike. The second power source (303) is used to provide electrical energy for the electromagnetic valve (301). The filter cover (304) has the function of filtering external moisture and salts.

2. The valve device (3) according to claim 1, characterized in that: The valve devices (3) are distributed on the leeward side of the blade and are densely arranged adjacent to the lightning arrester; they are sparsely arranged at positions far from the lightning arrester.

3. The electromagnetic valve (301) according to claim 1, characterized in that: The electromagnetic valve (301) is composed of an electromagnetic chuck (3011), a metal disc (3012), a concave outer shell (3013), a spring (3014), and a rubber patch (3015).

4. The filter cover (304) according to claim 1, characterized in that: The filter cover (304) is distributed at the notch of the concave outer shell (3013), and one side is aligned with the outer skin on the leeward side of the fan.

5. The auxiliary channel (302) according to claim 1, characterized in that: Low-quality and low-density small balls (3021) are placed inside the secondary channel (302). When the internal and external air pressures are balanced, the small balls (3021) block the secondary channel (302). When the external air pressure is greater than the internal air pressure, the external gas bounces the small balls (3021) to connect the internal and external spaces, thereby balancing the air pressure inside and outside the blade cavity after a lightning strike. Multiple secondary channels (302) are distributed around the recessed wall (4016) at the notch of the concave outer shell (4013) to connect the inner cavity of the fan blade and the notch of the concave outer shell (3013). The secondary channel inlet (3022) and the secondary channel outlet (3023) are circular, and their diameters are smaller than the diameter of the small balls (3021). The inner wall (3024) of the secondary channel is inclined to ensure that the small balls (3021) bounced off after the internal and external air pressures of the blade cavity are balanced can block the secondary channel inlet (3022). The secondary channel outlet (3023) should be equipped with a baffle to prevent the bounced small balls (3021) from flying out of the secondary channel (302).

6. The spring (3014) according to claim 3, characterized in that: The spring (3014) connects the metal disc (3012) and the concave outer shell (3013). In the normal closed state, the spring (3014) is in a stretched state to ensure that the metal disc (3012) and the concave outer shell (3013) are tightly fitted.

7. The rubber patch (3015) according to claim 3, characterized in that: The rubber patches (3015) are respectively placed at the joint of the metal disc (3012) and the concave outer shell (3013) to ensure that the metal disc (3012) and the concave outer shell (3013) are tightly fitted and play a buffering role during opening and closing.

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