Method for locating the broken point of lightning arrester wire on wind turbine blades based on traveling wave electrical quantity method

Abstract

The present invention discloses a method for locating the broken point of a lightning conductor on a wind turbine blade based on a traveling wave electrical quantity method. The present invention relates to the field of locating the broken point of a lightning conductor on a wind turbine blade, and includes an operation controller, a data acquisition device, a high-frequency current transformer, a step signal generator, and an adjustable resistor. By detecting the sudden change in electrical quantity under the conditions of traveling wave incidence and reflection, the time difference between the arrival of the incident wave and the reflected wave is determined, and the position of the breakpoint is determined according to the wave speed multiplied by the time difference divided by 2. The method for locating the broken point of a lightning conductor on a wind turbine blade based on a traveling wave electrical quantity method of the present invention can achieve high efficiency, accuracy, low cost, and convenient and flexible detection of the broken position of the lightning conductor. The method can be carried in one hand, enter the interior of a wind turbine, detect the continuity of the lightning conductor at the wind turbine hub, and determine the specific location of the broken conductor. After the broken conductor location is determined, targeted repairs can be performed at the specific location, saving the cost of replacing the lightning conductor.

Description

Technical Field

[0001] The invention relates to the field of positioning a broken point of a lightning arrester on a blade of a wind turbine generator, and in particular to a method for positioning a broken point of a lightning arrester on a blade of a wind turbine generator based on a traveling wave electrical quantity method. Background Art

[0002] Wind turbines are often located in mountainous and coastal areas, where lightning is common. Their high altitude makes them susceptible to lightning strikes, which can severely damage the power generation system and lead to prolonged downtime, resulting in significant economic losses. Furthermore, wind turbines are expensive to build, and the cost of repairing, dismantling, and replacing damaged components is substantial. Therefore, the integrity of lightning conductors is crucial for the safe operation of wind turbines. However, during extended operation, the lightning conductors in the blades are subject to certain tension. This, coupled with repeated lightning current shocks and aging, can lead to serious failures such as strand breakage or even fracture. Therefore, detecting broken lightning conductors in wind turbine blades is crucial throughout the design and operation of wind turbines.

[0003] The main traditional method currently used on-site both domestically and internationally is to connect a wire to the outside of the blade to form a loop with the lightning conductor, and then use Ohm's law to measure continuity. This method requires workers to be lowered in a hanging basket, making it inefficient and expensive. A new research direction is the detection of lightning conductor breakage based on the principle of single-ended traveling wave ranging. Its main principle is to inject a pulse signal into one end of the lightning conductor through a signal generator, and simultaneously use a sensor to obtain the lightning conductor echo signal. The length of the lightning conductor is calculated from the echo signal to determine the break location of the lightning conductor. The key to implementing this method is the accurate detection of the echo signal arrival time. Due to the limited length of the blade lightning conductor, the echo time is in the nanosecond range.

[0004] Currently, there are two problems with this method: First, the oscillation and tail time of the incident pulse signal is long and the waveform is complex. When the breakpoint is close to the detection point, the oscillation and tail of the reflected wave and the incident wave overlap, making it difficult to analyze the arrival time of the incident wave. Therefore, traditional single-ended traveling wave ranging methods usually have certain blind spots. Second, because traveling wave detection uses electromagnetic induction, spatial magnetic fields, uneven conductors, and bending conditions will add noise signals to the weak induction signal. Moreover, changing the detection object and environment will affect the waveform of the traveling wave voltage and current. Therefore, using peak analysis, wavelet analysis, feature point learning and training methods to analyze the arrival time of the traveling wave voltage or current has a certain degree of robustness, resulting in large deviations in measurement.

[0005] Therefore, it is necessary to propose a method for locating the broken point of the wind turbine blade lightning arrester based on the traveling wave electrical quantity method to solve the above problems. Summary of the Invention

[0006] The main purpose of the present invention is to provide a method for locating the broken point of a lightning arrester on a wind turbine blade based on a traveling wave electrical quantity method, which can effectively solve the problems in the background technology.

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

[0008] A method for locating the broken point of a wind turbine blade lightning arrester based on the traveling wave electrical quantity method includes an operation controller, a data collector, a high-frequency current transformer, a step signal generator, and an adjustable resistor. The operation controller is responsible for the process logic control, operation data processing, result display, and necessary human-computer interaction control of the entire system; the data collector is a high-speed data acquisition device, including at least 1GHz sampling and 100MHz bandwidth; the high-frequency current transformer is a traveling wave current acquisition device, requiring a response speed of nanoseconds and a bandwidth of at least 50MHz, based on the working principle of a Rogowski coil; the step signal generator is used to generate a DC10-30V adjustable step signal with a rising edge of less than 20ns according to a given signal from the operation controller; the adjustable resistor is connected in series before the line to be tested and can appropriately adjust the oscillation and tailing of the traveling wave current according to the impedance characteristics of different types of cables. The method specifically includes the following operating steps:

[0009] S1: First, start the rising edge trigger of the data collector, then start by giving a step signal through the step signal generator, and cooperate with the high-frequency current transformer to collect the data of the line to be tested. When the data collector collects valid signals, it selects a complete data segment based on the longest length of the line to be tested and the speed of the traveling wave;

[0010] S2: When the data collected by S1 is incomplete, the data collector is restarted and basic low-pass filtering and window selection are performed on the complete data for further analysis and calculation;

[0011] S3: Calculation of the traveling wave power value, according to the formula:

[0012] q=∫I(t)dt; where the electric quantity Q can be calculated by integrating the current I with the time t, I(t) is the function of the current with respect to the variable t, and dt indicates that the integral variable is t; because the current data collected by the data logger is a discrete quantity {I0, I1, I2...I n}, and the time interval of discrete quantities is fixed to the sampling period Ts, so the trapezoidal approximation method I0×T s +I1×T s +I2×T s +...I n ×T s , the amount of electricity Q can be calculated;

[0013] Based on the calculation controller, the current data is integrated on the time axis to calculate the traveling wave power value. By analyzing the sudden change of the traveling wave power, the time difference Δt between the incident wave and the reflected wave is found. According to the traveling wave theory, when the line end is short-circuited, the voltage is totally reflected and the current is totally reflected. When the incident wave arrives, the power has an upward inflection point, and when the reflected wave arrives, the power has a downward inflection point. The difference between the two inflection point times is Δt.

[0014] S4: Based on the calculated Δt and the known wave velocity V, the calculation formula for the breakpoint position is:

[0015]

[0016] The distance between the breakpoint of the line to be tested and the test point can be calculated. By comparing the breakpoint distance with the original length, it can be determined whether the lightning conductor is broken and where the breakpoint is.

[0017] The traveling wave velocity V of the measured line can be calibrated in advance, that is, Δts is measured in advance through a line of known length Ls, and then calculated. The formula is:

[0018] V=2×Ls÷Δts;

[0019] S5: When a break point of the line to be measured is detected, the current break point is manually repaired. After the repair is completed, the break point of the line to be measured is measured again. If there is a break point, it is repaired. If not, the measurement is stopped.

[0020] Preferably, in S1, when a line with a maximum length of 200 m and a wave speed of 200 m / us is selected, data sampled for at least 2 us from the time the trigger is valid constitutes a complete data segment.

[0021] Preferably, in S3, a low-voltage step voltage signal is given to the measuring end of the line to be measured as an excitation source, and a forward traveling wave current is generated on the line to be measured, which is called an incident wave. When the incident wave encounters a breakpoint during transmission along the line to be measured, refraction and reflection of the traveling wave will occur, and the reverse traveling wave current reflected back is called a reflected wave.

[0022] Preferably, an adjustable resistor is connected in series before the measuring end of the line to be measured, so as to reduce the oscillation and tailing amplitude and duration of the incident wave by adjusting the line impedance, so as to reduce the detection blind area.

[0023] Preferably, in S3, if the accuracy of Δt needs to be improved, the time window range of the charge mutation in the case of reflection phenomenon is further analyzed in combination with the changing trend of the traveling wave current waveform to find the arrival moment of the reflected wave and analyze the traveling wave charge mutation, thereby improving the accuracy, stability and consistency of the detection.

[0024] Compared with the prior art, the present invention provides a method for locating the broken point of a lightning arrester on a wind turbine blade based on the traveling wave electrical quantity method, which has the following beneficial effects:

[0025] This method for locating the broken point of the lightning conductor on the blade of a wind turbine generator based on the traveling wave electrical quantity method can achieve efficient, accurate, low-cost, and convenient and flexible detection of the broken position of the lightning conductor. It can be carried with one hand and entered into the wind turbine to detect the continuity of the lightning conductor at the wind turbine hub and determine the specific location of the broken wire. After the broken wire location is determined, targeted repairs can be carried out at the specific location, saving the cost of replacing the lightning conductor. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a topological diagram of the present invention;

[0027] Figure 2 This is a single operation flow chart of the present invention for positioning and measuring the broken point of the lightning protection wire of the wind turbine blade;

[0028] Figure 3 It is a schematic diagram of the traveling wave current and electric quantity waveform of the present invention.

[0029] Figure 3 The middle left picture shows the traveling wave current collected by the high-frequency current transformer, and the right picture shows the traveling wave quantity after the traveling wave current is integrated. DETAILED DESCRIPTION

[0030] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0031] Example 1:

[0032] like Figure 1-Figure 3 As shown in the figure, a method for locating the broken point of a wind turbine blade lightning arrester based on the traveling wave electrical quantity method includes an operation controller, a data acquisition device, a high-frequency current transformer, a step signal generator, and an adjustable resistor. The operation controller is responsible for the process logic control, operation data processing, result display, and necessary human-computer interaction control of the entire system; the data acquisition device is a high-speed data acquisition device, including at least 1GHz sampling and 100MHz bandwidth; the high-frequency current transformer is a traveling wave current acquisition device, requiring a response speed of nanoseconds and a bandwidth of at least 50MHz, based on the working principle of the Rogowski coil; the step signal generator is used to generate a step signal with an adjustable DC10-30V and a rising edge of less than 20ns according to the given signal of the operation controller; the adjustable resistor is connected in series before the line to be tested, and the oscillation and tailing of the traveling wave current can be appropriately adjusted according to the impedance characteristics of different types of cables. The specific operation steps include the following:

[0033] S1: First, start the rising edge trigger of the data collector, then give a step signal through the step signal generator to start, and cooperate with the high-frequency current transformer to collect the data of the line to be tested. When the data collector collects valid signals, it selects a complete data segment based on the maximum length of the line to be tested and the speed of the traveling wave. When a line with a maximum length of 200m and a speed of 200m / us is selected, data sampled for at least 2us from the time the trigger is valid is considered a complete data segment.

[0034] S2: When the data collected by S1 is incomplete, the data collector is restarted and basic low-pass filtering and window selection are performed on the complete data for further analysis and calculation;

[0035] S3: Calculation of the traveling wave power value, according to the formula:

[0036] Q = ∫I(t)dt;

[0037] The electric quantity Q can be calculated by integrating the current I with the time t. I(t) is the function of the current with respect to the variable t, and dt indicates that the integral variable is t. Because the current data collected by the data logger is a discrete quantity {I0, I1, I2...I n}, and the time interval of discrete quantities is fixed to the sampling period Ts, so the trapezoidal approximation method I0×T s +I1×T s +I2×T s +...I n ×T s , the amount of electricity Q can be calculated;

[0038] Based on the calculation controller, the current data is integrated on the time axis to calculate the traveling wave power value. By analyzing the sudden change of the traveling wave power, the time difference Δt between the incident wave and the reflected wave is found. According to the traveling wave theory, when the line end is short-circuited, the voltage is totally reflected and the current is totally reflected. When the incident wave arrives, the power has an upward inflection point, and when the reflected wave arrives, the power has a downward inflection point. The difference between the two inflection point times is Δt.

[0039] A low-voltage step voltage signal is applied to the measuring end of the line to be measured as an excitation source. This generates a forward traveling wave current on the line to be measured, which is called the incident wave. When the incident wave encounters a breakpoint along the line to be measured, refraction and reflection of the traveling wave will occur. The reflected reverse traveling wave current is called the reflected wave.

[0040] An adjustable resistor is connected in series before the measuring end of the line to be measured. This is used to reduce the oscillation and tailing amplitude and duration of the incident wave by adjusting the line impedance, thereby reducing the detection blind area. If the accuracy of Δt needs to be improved, the time window range of the power mutation in the case of reflection phenomenon can be further analyzed in combination with the changing trend of the traveling wave current waveform to find the arrival moment of the reflected wave and analyze the traveling wave power mutation. Based on this, the accuracy, stability and consistency of the detection can be improved.

[0041] S4: Based on the calculated Δt and the known wave velocity V, the calculation formula for the breakpoint position is:

[0042]

[0043] The distance between the breakpoint of the line to be tested and the test point can be calculated. By comparing the breakpoint distance with the original length, it can be determined whether the lightning conductor is broken and where the breakpoint is.

[0044] The traveling wave velocity V of the measured line can be calibrated in advance, that is, Δts is measured in advance through a line of known length Ls, and then calculated. The formula is:

[0045] V=2×Ls÷Δts;

[0046] The distance between the breakpoint of the line to be tested and the test point can be calculated. By comparing the breakpoint distance with the original length, it can be determined whether the lightning conductor is broken and where the breakpoint is.

[0047] S5: When a break point of the line to be measured is detected, the current break point is manually repaired. After the repair is completed, the break point of the line to be measured is measured again. If there is a break point, it is repaired. If not, the measurement is stopped.

[0048] Example 2:

[0049] The method for locating the broken point of the lightning arrester on a wind turbine blade based on the traveling wave electrical quantity method includes the following steps:

[0050] S1: A low-voltage step voltage signal is applied to the measuring end of the line under test as an excitation source. This generates a forward traveling wave current on the line under test, which is called the incident wave. When the incident wave encounters a breakpoint along the line under test, it will be refracted and reflected. The reflected reverse traveling wave current is called the reflected wave.

[0051] S2: An adjustable resistor is connected in series before the measuring end of the line to be tested. By adjusting the line impedance, the oscillation and tail amplitude and duration of the incident wave are reduced, which is used to reduce the detection blind area.

[0052] S3: Use a high-frequency current transformer to collect traveling wave current at the measuring end of the line to be measured. Then integrate the current data on the time axis to calculate the traveling wave power value. By analyzing the traveling wave power mutation, find the time difference Δt between the incident wave and the reflected wave. If the accuracy needs to be improved, the power mutation time window range in the case of reflection phenomenon is further analyzed in combination with the changing trend of the traveling wave current waveform to find the arrival moment of the reflected wave. Analyzing the traveling wave power mutation is used to improve the accuracy, stability and consistency of the detection.

[0053] S4: By measuring a cable of the same type as the cable to be tested with a known length of Ls in advance

[0054] Δts, reverse calibration of the traveling wave velocity of the line to be tested is:

[0055] V=2×Ls÷Δts;

[0056] S5: According to the TDR principle, the line to be tested The distance between the breakpoint of the line to be tested and the test point can be calculated.

[0057] Example 3:

[0058] The method for locating the broken point of the lightning protection line of the wind turbine blade based on the traveling wave power method is as follows: Figure 2 The figure shows a flow chart of a single measurement of the location of a lightning conductor break. When the measurement starts, the rising edge trigger of the data logger is first activated, and then a step signal is given to start. When the data logger collects a valid signal, it usually selects a complete data segment based on the maximum length of the line to be measured and the speed of the traveling wave. For example, if the line is 200m long and the speed is 200m / us, a complete data segment is formed by sampling data of at least 2us from the time the trigger is valid.

[0059] If the data is incomplete, it is necessary to restart the measurement. For complete data, basic low-pass filtering and window selection are required to facilitate further analysis and calculation;

[0060] Electric quantity is a physical quantity that describes the movement of electric charges in an electromagnetic field. It is usually represented by the symbol Q. The rate of change of electric quantity over time is the current, and the rate of change of electric quantity over time is the integral of the current, that is, the electric quantity itself. The analysis method is based on the formula: Q = ∫I(t)dt. The current data is integrated on the time axis to calculate the traveling wave electric quantity value. By analyzing the sudden change of traveling wave electric quantity, the time difference Δt of the accurate arrival time of the incident wave and the reflected wave is found, such as Figure 3 As shown, the left figure is the traveling wave current collected by the high-frequency current transformer, and the right figure is the traveling wave quantity after the traveling wave current is integrated. According to the traveling wave theory, when the line end is short-circuited, the voltage is fully reflected and the current is fully reflected. Figure 3As shown in the right figure, when the incident wave arrives, the charge has an upward inflection point, and when the reflected wave arrives, the charge has a downward inflection point. The difference between the two inflection point times is Δt. According to the formula: The distance between the breakpoint of the test line and the test point can be calculated. By comparing the breakpoint distance with the original length, it can be determined whether the line is broken and where the breakpoint is.

[0061] When the incident wave encounters a breakpoint during transmission, there will be obvious reflection. When the traveling wave power is detected, it will be found that the traveling wave power increases significantly when the incident wave arrives, and decreases significantly when the reflected wave arrives. Figure 3 As shown in the right figure, other clutter is very small compared to the energy of the incident wave and the reflected wave, and the slight change in the amount of electricity caused can be ignored. It can be automatically filtered by the algorithm. Only when the continuous amplitude changes significantly and exceeds a threshold, such as the rise rate > 1nc / ns and the fall rate <-2nc / ns, it is considered a mutation. Figure 3 As shown in the picture on the right.

[0062] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for locating the broken point of a wind turbine blade lightning arrester based on the traveling wave power method, comprising an operation controller, a data collector, a high-frequency current transformer, a step signal generator, and an adjustable resistor, characterized in that: The operation controller is responsible for the process logic control, operation data processing, result display and necessary human-computer interaction control of the entire system; the data collector is a high-speed data acquisition device, including at least 1GHz sampling frequency and 100MHz bandwidth; the high-frequency current transformer is a traveling wave current acquisition device, requiring a response speed of nanoseconds and at least 50MHz bandwidth, based on the working principle of the Rogowski coil; the step signal generator is used to generate a DC10-30V adjustable step signal with a rising edge of less than 20ns based on the given signal of the operation controller; the adjustable resistor is connected in series before the line to be tested, and appropriately adjusts the oscillation and tailing of the traveling wave current according to the impedance characteristics of different types of cables, and specifically includes the following operating steps: S1: First, start the rising edge trigger of the data collector, then give a step signal through the step signal generator, and use the high-frequency current transformer to collect the data of the line to be tested. When the data collector collects valid signals, it selects a complete data segment based on the longest length of the line to be tested and the speed of the traveling wave; S2: When the data collected by S1 is incomplete, the data collector is restarted and basic low-pass filtering and window selection are performed on the complete data for further analysis and calculation; S3: Calculation of the traveling wave power value, according to the formula: The amount of electricity The current I versus time Integral calculation, is the current logarithm function, The integral variable is ; Because the current data collected by the data collector is discrete { }, and the time interval of discrete quantities is fixed to the sampling period T s , so by the trapezoidal approximation , you can calculate the power ; Based on the calculation controller, the current data is integrated on the time horizontal axis to calculate the traveling wave power value. By analyzing the sudden change of the traveling wave power, the time difference between the incident wave and the reflected wave is found. According to the traveling wave theory, when the line end is short-circuited, the voltage is positively reflected and the current is negatively reflected. When the incident wave arrives, the charge has an upward inflection point, and when the reflected wave arrives, the charge has a downward inflection point. The difference between the two inflection point times is , S4: calculated , the known wave speed In the case of , the calculation formula of the break point position is: ； The distance between the breakpoint of the line to be tested and the test point can be calculated. By comparing the breakpoint distance with the original length, it can be determined whether the lightning conductor is broken and where the breakpoint is. The traveling wave velocity of the measured line Pre-calibration, that is, through a known length of Ls The line is measured in advance , and then calculate, the formula is: ； S5: When a break point of the line to be measured is detected, the current break point is manually repaired. After the repair is completed, the break point of the line to be measured is measured again. If there is a break point, it is repaired. If not, the measurement is stopped.

2. The method for locating the broken point of a lightning arrester on a wind turbine blade based on the traveling wave electrical quantity method according to claim 1, characterized in that: In S1, when a line of 200 m is selected at the longest and the wave speed is 200 m / us, data sampled for at least 2 us from the time the trigger is valid constitutes a complete data segment.

3. The method for locating the broken point of a lightning arrester on a wind turbine blade based on the traveling wave electrical quantity method according to claim 1, characterized in that: In S3, a low-voltage step voltage signal is applied to the measuring end of the line to be measured as an excitation source, generating a forward traveling wave current on the line to be measured, which is called an incident wave. When the incident wave encounters a breakpoint along the line to be measured, refraction and reflection of the traveling wave will occur, and the reverse traveling wave current reflected back is called a reflected wave.

4. The method for locating a broken point of a lightning arrester on a wind turbine blade based on the traveling wave electrical quantity method according to claim 1, characterized in that: In S3, if you need to improve The accuracy of the detection is improved by combining the time window range of the power mutation in the case of reflection phenomenon with the changing trend of the traveling wave current waveform to find the arrival moment of the reflected wave and analyze the traveling wave power mutation, thereby improving the accuracy, stability and consistency of the detection.

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