Fan blade self-energy-taking lightning current monitoring device and method

Abstract

The invention provides a fan blade self-energy-taking lightning current monitoring device and method.The fan blade self-energy-taking lightning current monitoring device comprises an induction triggering unit, the induction triggering unit is composed of a passive coil, and the passive coil is connected with a blade grounding down lead used for lightning current drainage; the induction trigger unit is connected with the lightning current recording unit and the wireless communication unit. The lightning current wave recording unit is used for collecting lightning current waveforms passing through a blade grounding down lead and storing the lightning current waveforms in a wave recording device. The wireless communication unit is used for returning lightning current time domain waveforms to maintenance personnel; the lightning current wave recording unit and the wireless communication unit are connected with the self-energy-taking power supply unit at the same time, and the self-energy-taking power supply unit is used for converting kinetic energy of the blade into electric energy and driving the lightning current wave recording unit and the wireless communication unit to work normally. According to the device and the method, the defects in the prior art can be overcome, the lightning current of the fan blade can be accurately monitored and recorded, the equipment installation and maintenance operation is simplified, and the operation safety and the management efficiency of a wind power plant are improved.

Description

Technical Field

[0001] The invention relates to the field of wind power generation engineering and current measurement technology, and in particular to a wind turbine blade self-energy lightning current monitoring device and method. Background Art

[0002] Lightning strikes are an important cause of damage to wind turbine blades. Lightning strikes not only cause damage to the blade composite structure, but can also cause fires and major accidents such as wind turbine shutdowns. Wind turbine blades conduct lightning current by setting multiple metal lightning receptors on the surface and connecting them to the internal grounding conductor. However, when the lightning strike position deviates from the lightning receptor or the grounding conductor has poor contact, incorrect discharge of lightning current is usually the direct cause of lightning strike accidents. Therefore, accurately monitoring and recording the lightning current waveform of wind turbine blades is of great significance for accurately analyzing and diagnosing the causes of wind turbine blade damage accidents and improving the lightning protection level of wind turbines.

[0003] There are two main technical solutions for wind turbine blade lightning current monitoring: passive and active. Among them, the passive monitoring method mainly uses a magnetic steel bar or a magnetic card arranged at the root of the blade grounding down conductor to record the peak value of the lightning current. Specifically, when the lightning current passes through the down conductor, the magnetic field generated by the lightning current magnetizes the magnetic steel bar or the magnetic card. Since the magnetic steel bar has a strong magnetic coercive characteristic, the magnetic steel bar can still retain a large residual magnetism after the lightning current passes through. By detecting the size of its residual magnetism, the magnitude of the measured lightning current amplitude can be determined. This passive measurement method does not require an external power supply, has low cost, and is easy to install. It is currently widely used in lightning current monitoring of wind turbines. However, the main limitations of the passive method are: ① This method can only record the peak value of the lightning current, and cannot provide the time domain waveform information of the lightning current, which is difficult to meet the needs of lightning fault analysis and judgment of the unit; ② The real-time monitoring is poor and data acquisition is difficult. This method requires operation and maintenance personnel to regularly climb to the cabin impeller to remove the magnetic card for reading and analyzing the recorded data, which increases the operation and maintenance cost and the complexity of data acquisition; ③ The accuracy of the measured data is insufficient. Due to the physical characteristics of the magnetic card, it may be affected by environmental factors, resulting in a decrease in the accuracy and reliability of the record.

[0004] Active monitoring technology mainly realizes real-time monitoring of the full waveform of lightning current by installing current sensors combined with high-speed digital acquisition devices. Since the hub and fairing at the root of the wind turbine blades are rotating structures, no power interface is reserved. Early active monitoring technology mainly arranged the lightning current measurement sensor at the bottom of the wind turbine tower, using the power supply provided by the step-up transformer to the low-voltage side of the unit to measure the waveform of the lightning current flowing through the down conductor to the bottom of the tower. However, due to the limitation of energy supply, the sensor was forced to be installed at the bottom of the tower close to the ground, and it was impossible to distinguish which blade was struck by lightning, making it difficult to determine the fault location in time. In addition, the lightning current wave is shunted and reflected by the down conductor and the tower, and its waveform and amplitude are also attenuated and distorted, which is not conducive to tracing the source of the lightning fault.

[0005] In recent years, active wind turbine blade lightning current waveform monitoring technology based on self-energy technology has developed rapidly. Chinese patent [CN202122883990.6] provides a Bluetooth-based wind turbine self-energy lightning current monitoring system. Its energy extraction method is to extract energy from the lightning current flowing through the down conductor through the mutual inductance coil, and store it in the capacitor module after rectification and filtering. Its main limitations are: ① The lightning strike of the wind turbine is a probabilistic event. Although the amplitude of the lightning current generated by a single lightning strike is extremely high, which can reach the order of kA, the duration of the lightning current is very short, which is the order of 100μs. Therefore, although the instantaneous power of the lightning current is very large, the energy generated after integration is not large. This is also the reason why humans do not capture lightning energy for use. The energy of the lightning current itself is not enough to drive the monitoring device. ② The lightning current has a large steepness and a high equivalent frequency, which can easily saturate the core of the mutual inductance coil and lose its energy extraction ability. Therefore, this technology cannot be applied in engineering. The wind turbine status monitoring technologies such as Chinese patents [CN201710208126.1] and [CN201420808931.X] use batteries or external power supplies as the energy source. Their main limitations are: ① The battery life is limited, especially in harsh environments with high temperature or high humidity, the battery life may be significantly shortened. The battery needs to be replaced or recharged regularly, which increases the maintenance workload and seriously affects the reliability of the monitoring device. ② The hub and fairing at the root of the wind turbine blade are rotating structures. Entering the hub rotating structure from the fixed cabin external power supply may cause the wires to be entangled, which may cause broken strands or even fires. Summary of the invention

[0006] In response to the above problems, the present invention provides a wind turbine blade self-energy lightning current monitoring device and method. This device and method can overcome the defects of the prior art, realize accurate monitoring and recording of lightning current on wind turbine blades, simplify equipment installation and maintenance operations, and improve the operating safety and management efficiency of wind farms.

[0007] In order to achieve the above technical features, the object of the present invention is achieved as follows: a wind turbine blade self-energy lightning current monitoring device, comprising an induction trigger unit, the induction trigger unit is composed of a passive coil, and the passive coil is connected to a blade grounding down conductor for lightning current drainage; The induction trigger unit is connected to the lightning current recording unit and the wireless communication unit; The lightning current recording unit is used to collect the lightning current waveform passing through the blade grounding down conductor and store it in the recording device; The wireless communication unit is used to transmit the lightning current time domain waveform back to the maintenance personnel; The lightning current recording unit and the wireless communication unit are simultaneously connected to a self-power supply unit, which is used to convert blade kinetic energy into electrical energy to drive the lightning current recording unit and the wireless communication unit to work normally.

[0008] When the lightning current flows through the down conductor, the low-voltage side of the passive coil senses and outputs a trigger pulse, which is transmitted to the lightning current recording unit and the wireless communication unit, thereby activating the lightning current monitoring device to collect the lightning current waveform.

[0009] The lightning current recording unit includes a Rogowski coil module, an integration circuit module and a recorder module; the Rogowski coil module is placed on the grounding down conductor at the root of the wind turbine blade, and the lightning current gradient is obtained based on the law of electromagnetic induction. The Rogowski coil module is connected to the integration circuit module, and the lightning current gradient is restored through the integration circuit module. The integration circuit module is connected to the recorder module, and the current waveform output by the integration circuit module is collected and stored through the recorder module.

[0010] The self-energy supply unit includes an energy collection module, an AC-DC conversion module and a supercapacitor network module; the energy collection module is used to convert the kinetic energy of the fan blades into alternating current, the output end of the energy collection module is connected to the AC-DC conversion module, the AC-DC conversion module is used to convert the alternating current into a stable direct current, the output end of the AC-DC conversion module is connected to the supercapacitor network module, and the supercapacitor network module absorbs the stable electric energy output by the AC-DC conversion module for storage.

[0011] The energy acquisition module consists of an insulating shell, a first fixed permanent magnet, a second fixed permanent magnet, a moving permanent magnet and an induction coil; the first fixed permanent magnet and the second fixed permanent magnet are installed at both ends of the insulating shell to enhance the magnetic field in the cavity of the insulating shell and increase the speed of the moving permanent magnet. The moving permanent magnet is freely placed in the cavity of the insulating shell. When the fan blades rotate, they reciprocate from the first fixed permanent magnet to the second fixed permanent magnet. The induction coil fits tightly into the cavity of the insulating shell and outputs alternating current based on the principle of electromagnetic induction.

[0012] The AC-DC conversion module includes a rectifier circuit, a filter circuit and a voltage stabilizing circuit, and is used to convert the alternating current generated by the induction coil into a stable direct current output.

[0013] A wind turbine blade self-energy lightning current monitoring method, the monitoring method is implemented by using the wind turbine blade self-energy lightning current monitoring device, comprising: The self-powered power supply unit uses a permanent magnet and an induction coil to form a motion mechanism. The potential energy change of the permanent magnet caused by the rotation of the fan blades cuts the magnetic lines of force to induce current in the coil, which is then collected by the supercapacitor after rectification, thereby continuously extracting energy when the fan blades are operating normally. By installing the entire lightning current monitoring device at the root of the wind turbine blade, it is usually in a low-power sleep state. When the blade is struck by lightning, the electromagnetic induction of the induction trigger unit passively triggers the lightning current recording unit, and the lightning current recording unit automatically records the lightning current waveform, and automatically analyzes the lightning current waveform characteristics, and then uses the wireless communication unit to send data wirelessly.

[0014] When the wind turbine blades operate normally, the average power of the self-powered power supply unit is above 5 mW.

[0015] The wireless communication unit adopts a Lora wireless communication module.

[0016] The present invention has the following beneficial effects: 1. The present invention can continuously and continuously obtain energy during the normal operation of the unit through the blade rotation energy extraction method, which is not affected by the number of lightning strikes. Combined with supercapacitor energy storage, it can ensure the normal functional requirements of the monitoring device during the start and stop of the unit. The device is small in size, low in cost, can be directly installed in the rotating hub, and has low safety risks.

[0017] 2. The sensor of the present invention is installed at the root of the blade and adopts low-power acquisition and passive triggering technology to realize real-time acquisition of lightning current waveform for a single blade, thereby accurately determining the location where the lightning fault occurs.

[0018] 3. The device of the present invention integrates the functions of automatic energy acquisition, waveform acquisition and wireless transmission, realizes real-time acquisition of monitoring data, operates reliably and is maintenance-free, and is of great significance to improving the operational safety and management efficiency of wind farms. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0020] Figure 1 This is a system framework diagram of the present invention.

[0021] Figure 2This is a structural diagram of the lightning current recording unit of the present invention.

[0022] Figure 3 This is a structural diagram of the self-power supply unit of the present invention.

[0023] In the figure: induction trigger unit 1, lightning current recording unit 2, wireless communication unit 3, self-energy supply unit 4; 21-Rogowski coil module; 22-integral circuit module; 23-wave recorder module; 41-energy acquisition module; 42-AC-DC conversion module; 43-supercapacitor network module; 411 - insulating shell; 412 - induction coil; 413 - first fixed permanent magnet; 414 - second fixed permanent magnet; 415 - moving permanent magnet. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by technical personnel in the field based on the above invention content still fall within the scope of protection of the present invention.

[0025] Embodiment 1: In view of the above defects and improvement needs of the prior art, and the problems that the existing wind turbine blade lightning current monitoring technology cannot accurately record the time domain waveform of the lightning current, the recording is difficult, and the self-energy collection is unstable, the present invention proposes a wind turbine blade self-energy collection lightning current monitoring device.

[0026] See also Figure 1A wind turbine blade self-energy lightning current monitoring device comprises an induction trigger unit 1, wherein the induction trigger unit 1 is composed of a passive coil, and the passive coil is connected to the blade grounding down conductor used for lightning current diversion; the induction trigger unit 1 is connected to a lightning current recording unit 2 and a wireless communication unit 3; the lightning current recording unit 2 is used to collect the lightning current waveform passing through the blade grounding down conductor and store it in the recording device; the wireless communication unit 3 is used to transmit the lightning current time domain waveform back to the maintenance personnel; the lightning current recording unit 2 and the wireless communication unit 3 are simultaneously connected to a self-energy power supply unit 4, and the self-energy power supply unit 4 is used to convert the blade kinetic energy into electrical energy, and drive the lightning current recording unit 2 and the wireless communication unit 3 to work normally. By adopting the above-mentioned lightning current monitoring device, the self-energy supply unit 4 uses a permanent magnet and an induction coil to form a motion mechanism, and uses the potential energy change of the permanent magnet caused by the rotation of the blade to cut the magnetic lines of force to induce current in the coil, and collects the current by the supercapacitor after rectification. It can continuously obtain energy when the wind turbine blades are operating normally, and solve the problem of unstable and low efficiency of self-energy extraction from lightning current; then the self-energy supply unit 4 is used to power the lightning current recording unit 2 and the wireless communication unit 3 at the same time. The lightning current monitoring device is installed at the down conductor at the root of the blade, and is usually in a low-power dormant state. When the blade is struck by lightning, the electromagnetic induction passive triggering of the induction trigger unit 1 is used, and the lightning current recording unit 2 automatically records the lightning current waveform, and realizes automatic analysis of the lightning current waveform characteristics, and the final data is wirelessly sent by the wireless communication unit 3.

[0027] Furthermore, when the lightning current flows through the down conductor, the low-voltage side of the passive coil senses and outputs a trigger pulse, which is transmitted to the lightning current recording unit 2 and the wireless communication unit 3, thereby activating the lightning current monitoring device to collect the lightning current waveform. The above-mentioned passive coil can be automatically triggered when lightning strikes.

[0028] For further information, see Figure 2 , the lightning current recording unit 2 includes a Rogowski coil module 21, an integration circuit module 22 and a recorder module 23; the Rogowski coil module 21 is placed on the grounding down conductor at the root of the fan blade, and the lightning current gradient is obtained based on the law of electromagnetic induction. The Rogowski coil module 21 is connected to the integration circuit module 22, and the lightning current gradient is restored through the integration circuit module 22. The integration circuit module 22 is connected to the recorder module 23, and the current waveform output by the integration circuit module 22 is collected and stored through the recorder module 23. The above-mentioned lightning current recording unit 2 is mainly used to record lightning. In the specific working process, the Rogowski coil module 21 is placed on the grounding down conductor at the root of the fan blade, and the lightning current gradient is obtained based on the law of electromagnetic induction. It is restored through the integration circuit module 22, and the output current waveform is finally collected and stored by the recorder module 23.

[0029] For further information, see Figure 3 The self-power supply unit 4 includes an energy supply module 41, an AC-DC conversion module 42 and a supercapacitor network module 43; the energy supply module 41 is used to convert the kinetic energy of the fan blades into alternating current, the output end of the energy supply module 41 is connected to the AC-DC conversion module 42, the AC-DC conversion module 42 is used to convert the alternating current into a stable direct current, the output end of the AC-DC conversion module 42 is connected to the supercapacitor network module 43, and the supercapacitor network module 43 absorbs the stable electric energy output by the AC-DC conversion module 42 for storage. The self-power supply unit 4 can be used to provide stable electric energy.

[0030] For further information, see Figure 3 The energy acquisition module 41 is composed of an insulating shell 411, a first fixed permanent magnet 413, a second fixed permanent magnet 414, a moving permanent magnet 415 and an induction coil 412; the first fixed permanent magnet 413 and the second fixed permanent magnet 414 are installed at both ends of the insulating shell 411, and are used to enhance the magnetic field in the cavity of the insulating shell 411 and increase the speed of the moving permanent magnet 415. The moving permanent magnet 415 is freely placed in the cavity of the insulating shell 411. When the fan blades rotate, they reciprocate from the first fixed permanent magnet 413 to the second fixed permanent magnet 414. The induction coil 412 fits tightly into the cavity of the insulating shell 411 and outputs alternating current based on the principle of electromagnetic induction.

[0031] For further information, see Figure 3 The AC-DC conversion module 42 includes a rectifier circuit, a filter circuit and a voltage stabilizing circuit, and is used to convert the alternating current generated by the induction coil 412 into a stable DC output.

[0032] Furthermore, the supercapacitor network module 43 absorbs the stable electric energy output by the AC-DC module 42 for storage, thereby improving the stability of the device output.

[0033] Embodiment 2: A method for monitoring lightning current of a wind turbine blade self-energy extraction, the monitoring method being implemented by a wind turbine blade self-energy extraction lightning current monitoring device according to any one of claims 1 to 6, comprising: The self-powered power supply unit 4 uses a permanent magnet and an induction coil to form a motion mechanism, and uses the potential energy change of the permanent magnet caused by the rotation of the fan blades to cut the magnetic lines of force to induce current in the coil, which is collected by the supercapacitor after rectification, so as to continuously obtain energy when the fan blades are operating normally; By installing the entire lightning current monitoring device at the root of the wind turbine blade, it is usually in a low-power sleep state. When the blade is struck by lightning, the electromagnetic induction of the induction trigger unit 1 passively triggers the lightning current recording unit 2, and the lightning current recording unit 2 automatically records the lightning current waveform, and realizes automatic analysis of the lightning current waveform characteristics, and then uses the wireless communication unit 3 to wirelessly send data.

[0034] Furthermore, when the wind turbine blades are operating normally, the average power of the self-power supply unit 4 is above 5 mW, thereby solving the problem of unstable and low efficiency of self-power supply due to lightning current.

[0035] Furthermore, the wireless communication unit 3 adopts a Lora wireless communication module. The wireless communication unit 3 can be used to wirelessly send the generated data to the operation and maintenance personnel.

[0036] The present invention is the embodiment of the present invention as described above. The above embodiments and the specific parameters in the embodiments are only for the purpose of clearly describing the invention verification process, and are not used to limit the patent protection scope of the present invention. The patent protection scope of the present invention is still subject to its claims. Any equivalent structural changes made by using the description and drawings of the present invention should be included in the protection scope of the present invention.

Claims

1. A wind turbine blade self-powered lightning current monitoring device, characterized in that: It comprises an induction trigger unit (1), wherein the induction trigger unit (1) is composed of a passive coil, and the passive coil is connected to a blade grounding down conductor used for lightning current drainage; The induction trigger unit (1) is connected to the lightning current recording unit (2) and the wireless communication unit (3); The lightning current recording unit (2) is used to collect the lightning current waveform passing through the blade grounding down conductor and store it in the recording device; The wireless communication unit (3) is used to transmit the lightning current time domain waveform back to the maintenance personnel; The lightning current recording unit (2) and the wireless communication unit (3) are simultaneously connected to a self-power supply unit (4), and the self-power supply unit (4) is used to convert blade kinetic energy into electrical energy, thereby driving the lightning current recording unit (2) and the wireless communication unit (3) to work normally.

2. A wind turbine blade self-energy lightning current monitoring device according to claim 1, characterized in that: When the lightning current flows through the down conductor, the low-voltage side of the passive coil senses and outputs a trigger pulse, which is transmitted to the lightning current recording unit (2) and the wireless communication unit (3), thereby activating the lightning current monitoring device to collect the lightning current waveform.

3. A wind turbine blade self-energy lightning current monitoring device according to claim 1, characterized in that: The lightning current recording unit (2) comprises a Rogowski coil module (21), an integration circuit module (22) and a recorder module (23); the Rogowski coil module (21) is placed on the grounding down conductor at the root of the wind turbine blade, and a lightning current gradient is obtained based on the law of electromagnetic induction; the Rogowski coil module (21) is connected to the integration circuit module (22), and the lightning current gradient is restored through the integration circuit module (22); the integration circuit module (22) is connected to the recorder module (23), and the current waveform output by the integration circuit module (22) is collected and stored through the recorder module (23).

4. A wind turbine blade self-energy lightning current monitoring device according to claim 1, characterized in that: The self-power supply unit (4) comprises an energy collection module (41), an AC-DC conversion module (42) and a supercapacitor network module (43); the energy collection module (41) is used to convert the kinetic energy of the fan blades into alternating current, the output end of the energy collection module (41) is connected to the AC-DC conversion module (42), the AC-DC conversion module (42) is used to convert the alternating current into a stable direct current, the output end of the AC-DC conversion module (42) is connected to the supercapacitor network module (43), and the supercapacitor network module (43) absorbs the stable electric energy output by the AC-DC conversion module (42) for storage.

5. A wind turbine blade self-energy lightning current monitoring device according to claim 1, characterized in that: The energy acquisition module (41) is composed of an insulating shell (411), a first fixed permanent magnet (413), a second fixed permanent magnet (414), a moving permanent magnet (415), and an induction coil (412); the first fixed permanent magnet (413) and the second fixed permanent magnet (414) are installed at two ends of the insulating shell (411) to enhance the magnetic field in the cavity of the insulating shell (411) and to increase the speed of the moving permanent magnet (415); the moving permanent magnet (415) is freely placed in the cavity of the insulating shell (411); when the fan blades rotate, they reciprocate from the first fixed permanent magnet (413) to the second fixed permanent magnet (414); the induction coil (412) is tightly fitted in the cavity of the insulating shell (411), and outputs alternating current based on the principle of electromagnetic induction.

6. A wind turbine blade self-energy lightning current monitoring device according to claim 5, characterized in that: The AC-DC conversion module (42) comprises a rectifier circuit, a filter circuit and a voltage stabilization circuit, and is used to convert the alternating current generated by the induction coil (412) into a stable direct current output.

7. A method for monitoring lightning current of wind turbine blades, characterized in that: The monitoring method is implemented by using a wind turbine blade self-energy lightning current monitoring device as described in any one of claims 1 to 6, comprising: The self-powered power supply unit (4) uses a permanent magnet and an induction coil to form a motion mechanism, and utilizes the potential energy change of the permanent magnet caused by the rotation of the fan blades to cut the magnetic lines of force to induce current in the coil, and collects the current through the supercapacitor after rectification, thereby continuously extracting energy when the fan blades are operating normally; The entire lightning current monitoring device is installed at the down conductor at the root of the wind turbine blade, which is normally in a low-power sleep state. When the blade is struck by lightning, the electromagnetic induction of the induction trigger unit (1) passively triggers the lightning current recording unit (2), and the lightning current recording unit (2) automatically records the lightning current waveform, and automatically analyzes the characteristics of the lightning current waveform, and then uses the wireless communication unit (3) to wirelessly transmit the data.

8. A wind turbine blade self-energy lightning current monitoring method according to claim 7, characterized in that: When the wind turbine blades are operating normally, the average power of the self-powered power supply unit (4) is above 5 mW.

9. A wind turbine blade self-energy lightning current monitoring method according to claim 7, characterized in that: The wireless communication unit (3) adopts a Lora wireless communication module.

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