Method for detecting lightning conductor fault of blade of wind turbine generator by adopting high-frequency pulse

Abstract

The invention discloses a method for detecting wind turbine blade lightning conductor faults by adopting high-frequency pulses. The method comprises the following steps: S1, constructing lightning conductor equivalent models of intact wind turbine blade lightning conductors, open circuit faults and short circuit faults; s2, setting variable factor control groups of different pulse widths and different amplitudes of the pulse generator and different distribution parameters of the lightning conductor; s3, comparing the oscillograms of different types of faults, performing type identification and positioning verification on the lightning conductor faults, and comparing the oscillograms under different influence factors to determine influence factors of a detection result; s4, determining pulse parameters; s5, a pulse generator is used for transmitting pulses along the lightning conductor, and when the voltage of the first reflected wave is forward voltage, a broken line fault is judged; when the first reflected wave is the negative pulse width and the lightning conductor voltage, a short-circuit fault is determined; positioning a fault point according to t = 2 * X / V; otherwise, the lightning conductor is intact. The method is convenient to operate, simple and feasible, and accurate in detection result.

Description

Technical Field

[0001] The present invention relates to a method for detecting faults in the lightning protection wire of a wind turbine blade, and particularly to a method for detecting faults in the lightning protection wire of a wind turbine blade using high-frequency pulses. Background Art

[0002] Wind turbines are usually built in mountainous areas or near the coastline and are relatively tall, so the probability of being struck by lightning is relatively high. The wind turbine blade is the component most vulnerable to lightning strikes in the unit. Since the blade is made of fiber materials, high-energy lightning current can only be introduced into the ground through the lightning protection wire.

[0003] Currently, the lightning protection wire metal conductor is mainly installed on the surface or inside of the blade, guiding the lightning current to the root of the blade and introducing it into the ground through the equipotential connection system between the tower barrel and the hub. However, when a fault occurs in the lightning discharge path, an arcing phenomenon will occur at the broken wire, generating high temperature instantly, resulting in blade cracking or even blade explosion, causing huge economic losses to the wind farm.

[0004] To avoid losses, it is necessary to detect faults in the lightning protection wire of the wind turbine blade. The problem of detecting faults in the lightning protection wire of the wind turbine blade is a difficult problem in the operation management of wind turbines. Experts at home and abroad have carried out a lot of research and applications on this, but there are problems such as cumbersome on-site applications and low detection efficiency.

[0005] Currently, the main lightning protection wire testing methods at home and abroad utilize Ohm's law in the circuit.

[0006] Principle of Ohm's law detection method: Apply voltage at both ends of the lightning protection wire. When the lightning protection wire is intact without breaks, the resistance value is extremely small under the action of the applied voltage, while for a lightning protection wire with defects such as broken strands or complete breaks, the resistance value is relatively large under the action of the applied voltage.

[0007] Therefore, when testing the lightning protection wire, the measured lightning protection wire must form a complete closed loop. The lightning protection wire and downlead under the tower of the wind turbine can be measured for the closed loop through an external detection instrument to obtain a relatively accurate loop resistance. However, for the lightning protection wire of the wind turbine blade, because the entire testing process requires connecting the lightning arrester at the tip of the wind turbine blade, the operation is very inconvenient. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for detecting faults in the lightning protection wire of a wind turbine blade using high-frequency pulses, which is convenient to operate, simple and easy to implement, and has accurate detection results.

[0009] The purpose of the present invention is achieved through the following technical measures: A method for detecting faults in the lightning protection wire of a wind turbine blade using high-frequency pulses, characterized by including the following steps:

[0010] S1. Construct an equivalent model of the lightning protection wire for the blade of a wind turbine, including intact, open circuit fault, and short circuit fault models.

[0011] S2. Set up variable factor control groups for different pulse widths, different amplitudes of the pulse generator, and different distribution parameters of the lightning protection wire.

[0012] S3. Compare the waveform diagrams of different types of faults to identify and locate the type of lightning protection wire fault, and at the same time compare the waveform diagrams under different influencing factors to determine the influencing factors of the detection results.

[0013] S4. Determine the pulse parameters.

[0014] S5. Use the pulse generator to emit pulses along the lightning protection wire. When the voltage of the first reflected wave is a positive voltage, it is determined as an open circuit fault; when the first reflected wave is a negative pulse width and the voltage of the lightning protection wire, it is determined as a short circuit fault; and locate the fault point according to t = 2×X / V; otherwise, the lightning protection wire is intact.

[0015] The present invention uses high-frequency pulses to detect faults in the lightning protection wire of the blade of a wind turbine, which is convenient to operate, simple and easy to implement, and the detection results are accurate. It solves the technical problem in the prior art that the operation is very inconvenient because the lightning arrester at the tip of the wind turbine blade needs to be connected throughout the testing process.

[0016] The pulse width of the present invention is 100 - 200 ns.

[0017] The influencing factors of the detection results of the present invention are the pulse width, the capacitance parameter of the lightning protection wire, and the inductance parameter of the lightning protection wire.

[0018] In the simulation experiment of the distribution parameters of the lightning protection wire of the present invention, for lightning protection wires of different types of conductors, a setting test is first carried out.

[0019] When the reference data of the lightning protection wire is lost in the present invention, the fault point of the lightning protection wire and the type of lightning protection wire fault are judged by analyzing the lightning protection wire model and equivalently calculating the capacitance and inductance parameters.

[0020] The pulse amplitude of the present invention is 5 - 24 V.

[0021] Compared with the prior art, the present invention has the following remarkable effects:

[0022] ⑴ The present invention uses high-frequency pulses to detect faults in the lightning protection wire of the blade of a wind turbine, which is convenient to operate, simple and easy to implement, and the detection results are accurate. It solves the technical problem in the prior art that the operation is very inconvenient because the lightning arrester at the tip of the wind turbine blade needs to be connected throughout the testing process.

[0023] ⑵ Using the present invention can conveniently eliminate faults such as broken strands and breaks in the lightning protection wires of the fan blades, and provide accurate diagnosis based on the measurement information, guiding on-site personnel to take preventive measures in a timely manner to eliminate potential hazards, providing early warning and proactive maintenance of the fan status for the site, thereby improving the reliability of the company's wind turbine operation, reducing maintenance costs and significant economic losses caused by faults, and generating greater economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0025] Figure 1 is a schematic diagram of the basic principle of the present invention;

[0026] Figure 2 is a fault-free lightning protection wire detection model of the present invention;

[0027] Figure 3 is a short-circuit fault lightning protection wire detection model of the present invention;

[0028] Figure 4 is a waveform diagram of the results of different fault simulation experiments of the present invention;

[0029] Figure 5 is a comparison waveform diagram of lightning protection wires with different pulse widths detected by the present invention;

[0030] Figure 6 is a comparison waveform diagram of lightning protection wires with different capacitances detected by the present invention;

[0031] Figure 7 is a comparison waveform diagram of lightning protection wires with different inductances detected by the present invention;

[0032] Figure 8 is a comparison waveform diagram of lightning protection wires with different pulse amplitudes detected by the present invention;

[0033] Figure 9 is a schematic diagram of detection using the detection device of the present invention;

[0034] Figure 10 is a waveform diagram displayed on the human-machine interface during the detection of the detection device. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The present invention will be described in detail below in conjunction with the embodiments and their accompanying drawings to help those skilled in the art better understand the inventive concept of the present invention. However, the protection scope of the claims of the present invention is not limited to the following embodiments. For those skilled in the art, all other embodiments obtained without creative labor on the premise of not departing from the inventive concept of the present invention belong to the protection scope of the present invention.

[0036] The present invention uses the pulse current method for positioning, and its basic principle is the wave process in high-voltage theory. For example, Figure 1 As shown, during the transmission of the pulse signal, it propagates along the lightning protection line in the form of an electromagnetic wave at a speed close to the speed of light. When it encounters a point with discontinuous wave impedance (i.e., the fault point), reflection and refraction phenomena will occur.

[0037] For example, Figures 2 to 8 As shown, a method for detecting faults in the lightning protection line of a wind turbine blade using high-frequency pulses according to the present invention includes the following steps:

[0038] S1. Use PSpice and Matlab software for circuit modeling to construct equivalent models of the lightning protection line of the wind turbine blade in good condition, open circuit fault, and short circuit fault.

[0039] Refer to Figure 2 , which is the equivalent model of the lightning protection line of the wind turbine blade in good condition; refer to Figure 3 , which is the equivalent model of the lightning protection line of the wind turbine blade with a short circuit fault.

[0040] S2. Set variable factor control groups with different pulse widths, different amplitudes of the pulse generator, and different distribution parameters of the lightning protection line.

[0041] S3. Compare the waveform diagrams of different types of faults to identify and locate the type of lightning protection line fault. At the same time, compare the waveform diagrams under different influencing factors to determine that the influencing factors of the detection results are the pulse width, capacitance parameter of the lightning protection line, and inductance parameter of the lightning protection line.

[0042] For example, Figure 4 As shown, it is the waveform diagram of a 100-meter lightning protection line in good condition, open circuit at the midpoint, and short circuit at the midpoint.

[0043] For example, Figure 5 As shown, it is the comparison waveform diagram of detecting a 50m lightning protection line with different pulse widths. It can be seen that if the pulse width is too wide, the signal aliasing accuracy is low; while if the pulse width is too short, the energy is insufficient and the signal attenuation cannot be detected.

[0044] For example, Figure 6 As shown, it is the comparison waveform diagram of detecting lightning protection lines with different capacitances. It can be seen that as the capacitance parameter of the lightning protection line increases, the propagation speed of the electromagnetic wave in the lightning protection line decreases, and the appearance time of the reflected wave is delayed; when the capacitance parameter of the lightning protection line is too small, the reflected wave will be distorted, and both the pulse width and amplitude will decrease; when the capacitance parameter of the lightning protection line is too large, the pulse width of the reflected wave will not change, but the positive and negative of the voltage of the reflected wave after the second one will change.

[0045] For example, Figure 7As shown, it is a comparison waveform diagram of the detection of 100-meter lightning protection wires with different inductances. It can be seen that as the inductance parameter of the lightning protection wire increases, the propagation speed of electromagnetic waves in the lightning protection wire decreases, and the appearance time of the reflected wave is delayed; when the inductance parameter of the lightning protection wire is too small, the reflected wave will be aliased, and the original pulse and the reflected wave cannot be distinguished; when the inductance parameter of the lightning protection wire is too large, the pulse width of the reflected wave will not change, but the positive and negative of the voltage of the reflected wave after the second one will change.

[0046] As Figure 8 shown, it is a comparison waveform diagram of the detection of a 100m lightning protection wire with different pulse amplitudes. Pulses of 10V, 60V, and 100V are applied to the lightning protection wire. The obtained reflected wave times are the same, and the reflected wave pulse widths are also the same. Only the amplitude of the reflected wave changes, which has no effect on judging the type and location of the lightning protection wire fault.

[0047] S4. Determine the pulse parameters. The pulse parameters include the pulse width and the pulse amplitude. Among them, the pulse width is 100 - 200ns, and the pulse amplitude is 5 - 24V;

[0048] The parameters of the pulse generator are shown in Table 1:

[0049]

[0050] (Table 1)

[0051] The model parameters of the lightning protection wire of the fan blade are shown in Table 2:

[0052]

[0053] (Table 2)

[0054] The capacitance and inductance of the circuit have a great influence on the detection result. Based on the completed simulation, the preferred pulse width for detecting faults is 200ns; in the simulation experiment of the distributed parameters of the lightning protection wire, the resistance and conductance parameters have little influence on the detection result. However, for lightning protection wires of different types of conductors, setting tests should be carried out first. At the same time, when the reference data of the lightning protection wire is lost in actual situations, the fault point of the lightning protection wire can also be equivalently calculated and the fault type of the lightning protection wire can be judged by analyzing the provided lightning protection wire model and capacitance and inductance parameters.

[0055] The pulse amplitude only affects the amplitude of the reflected wave, but does not affect the reflected wave time and pulse width, and has no effect on judging the type and location of the lightning protection wire fault. However, due to inevitable external interference factors, the higher the pulse amplitude applied to the lightning protection wire, the more significant the suppression effect on clutter and external interference. Selecting a higher amplitude pulse will improve the measurement accuracy.

[0056] S5. Use a pulse generator to transmit pulses along the lightning protection wire. When the voltage of the first reflected wave is a positive voltage, it is determined as an open - circuit fault; when the first reflected wave is a negative - pulse width and the voltage of the lightning protection wire, it is determined as a short - circuit fault; and locate the fault point according to t = 2×X / V, where X is the round - trip distance that the pulse propagates from the starting point of the lightning protection wire to the fault point, V is the propagation speed of the pulse, and t is the time required for the pulse to make a round - trip from the starting point of the lightning protection wire to the fault point; otherwise, the lightning protection wire is intact.

[0057] The simulation results of open - circuit and short - circuit faults at different positions are in line with the expected results. The appearance time of the first reflected wave is equal to the time required for the pulse to make a round - trip from the starting point of the lightning protection wire to the fault point, and the positioning is achieved through t = 2×X / V; for the open - circuit fault, the voltage of the first reflected wave is a positive voltage, and for the short - circuit fault, the first reflected wave is a negative - pulse width and the voltage of the lightning protection wire. By observing the positive or negative of the first reflected wave, the fault type can be determined.

[0058] Use the lightning protection wire fault detection device 1 of the present invention to detect the lightning protection wire. The detection device includes a housing and a circuit board built in the housing. Integrated on the circuit board are a battery unit (lithium - ion battery) connected to an external DC power supply, a power management unit connected to the battery unit, a high - performance processor, a human - machine interface provided on the housing, a display controller connected to the human - machine interface, a memory (including accessories such as a hard disk and memory), a signal acquisition board (ultra - high - speed signal acquisition board) for measuring pulse signals and their reflected waves, and a fully - solid - state programmable pulse power supply for emitting pulse current. The high - performance processor is respectively connected to the power management unit, the display controller, the memory, the signal acquisition board, and the fully - solid - state programmable pulse power supply. The battery unit is provided with a first connection port on the housing for connecting to the lightning protection wire of the wind turbine blade through an output wire 2 and a second connection port for connecting to the ground wire through a grounding wire 3. The first connection port is connected to the fully - solid - state programmable pulse power supply, and the second connection port is connected to the signal acquisition board.

[0059] As Figure 9 shown, when using the lightning protection wire fault detection device 1 of the wind turbine blade for detection, connect the lightning protection wire provided on the wind turbine blade 5 (the wind turbine blade 5 is installed on the slip ring 6) through the output wire 2 connected to the first connection port, and connect the ground wire (through the equipotential connection system of the wind turbine tower 4) through the grounding wire 3 connected to the second connection port.

[0060] During the test, use a 100 - meter cable, cut it at 70 meters, and use the detection device for detection. As Figure 10 shown, the reflected wave can be observed on the detection device, and it can be correctly located at 70 meters (the fault point), indicating that the detection device of the present invention can accurately and reliably determine the fault point and fault type of the cable.

Claims

1. A method for detecting the fault of the lightning protection wire of the wind turbine blade by using high-frequency pulses, characterized in that It includes the following steps: S1. Construct an equivalent model of the lightning protection wire for the blade of a wind turbine under the conditions of intact, open-circuit fault, and short-circuit fault; S2. Set variable factor control groups with different pulse widths, different amplitudes of the pulse generator, and different distribution parameters of the lightning protection wire; S3. Compare the waveform diagrams of different types of faults to identify and locate the type of lightning protection wire fault, and at the same time compare the waveform diagrams under different influencing factors to determine the influencing factors of the detection results; S4. Determine the pulse parameters; S5. Use the pulse generator to emit pulses along the lightning protection wire. When the voltage of the first reflected wave is a positive voltage, it is determined as an open-circuit fault; when the first reflected wave is a negative pulse width and the voltage of the lightning protection wire, it is determined as a short-circuit fault; and locate the fault point according to t = 2×X / V; otherwise, the lightning protection wire is intact.

2. The method for detecting the fault of the lightning protection wire of the wind turbine blade by using high-frequency pulses according to claim 1, characterized in that: In the step S4, the pulse parameters include the pulse width, and the pulse width is 100 - 200 ns.

3. The method for detecting the lightning protection wire fault of the wind turbine blade by using high-frequency pulses according to claim 2, wherein: In the step S4, the pulse parameters include the pulse amplitude, and the pulse amplitude is 5 - 24 V.

4. The method for detecting the lightning protection wire fault of the wind turbine blade by using high-frequency pulses according to claim 3, wherein: The influencing factors of the detection results are the pulse width, the capacitance parameter of the lightning protection wire, and the inductance parameter of the lightning protection wire.

5. The method for detecting the lightning protection wire fault of the wind turbine blade by using high-frequency pulse according to claim 4, characterized in that: In the simulation experiment of the distribution parameters of the lightning protection wire, for the lightning protection wire of different types of conductors, first conduct a setting test.

6. The method for detecting the fault of the lightning protection wire of the wind turbine blade by using high-frequency pulse according to claim 5, wherein: When the reference data of the lightning protection wire is lost, analyze the type of the lightning protection wire and the capacitance and inductance parameters to equivalently calculate the fault point of the lightning protection wire and judge the fault category of the lightning protection wire.

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