Wind driven generator blade lightning conductor broken line point positioning method based on traveling wave electricity method

Abstract

The invention discloses a wind driven generator blade lightning conductor broken line point positioning method based on a traveling wave electricity method, and relates to the field of wind driven generator blade lightning conductor broken line point positioning, which comprises an operation controller, a data collector, a high-frequency current transformer, a step signal generator and an adjustable resistor, the time difference of arrival of an incident wave and a reflected wave is judged by detecting the sudden change of electric quantity under the conditions of traveling wave incidence and reflection, and the position of a breakpoint is judged by multiplying the wave velocity by the time difference and dividing by 2. According to the wind driven generator blade lightning conductor broken line point positioning method based on the traveling wave electricity method, the broken line position of the lightning conductor can be detected efficiently, accurately, conveniently and flexibly at low cost, and the method can be carried by one hand to enter a fan to detect the on-off of the lightning conductor at a fan hub and determine the specific broken line position. And after the broken line position is determined, the specific position is repaired in a targeted manner, so that the cost for replacing the lightning conductor is saved.

Description

Technical Field

[0001] The invention relates to the field of positioning a broken line point of a lightning arrester on a blade of a wind turbine generator, and in particular to a method for positioning a broken line 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 mostly located in mountainous areas and seaside areas with frequent lightning. They are high in height and easily struck by lightning, which causes serious damage to the power generation system and leads to long shutdowns, resulting in huge economic losses. In addition, wind turbines are expensive, and repair, removal and replacement of damaged parts also require huge costs. Therefore, the integrity of the lightning conductor plays a vital role in the safe operation of wind turbines. During long-term operation, the lightning conductor in the blade is subjected to a certain tension, coupled with multiple shocks and aging problems of lightning current, resulting in serious faults such as broken strands or even fractures in the lightning conductor. Therefore, the detection of broken lightning conductors in wind turbine blades is crucial in the design and operation of the entire wind turbine.

[0003] At present, the main traditional method used on-site at home and abroad is to form a loop with the lightning conductor on the outside of the blade, and use Ohm's law to measure the continuity. This method requires the staff to be suspended from the hanging basket, so this method is inefficient and expensive. The lightning conductor break detection method based on the single-ended traveling wave ranging principle is the latest research direction. Its main principle is to inject a pulse signal into one end of the lightning conductor through a signal generator, and use a sensor to obtain the lightning conductor echo signal. The length of the lightning conductor is calculated by the echo signal to determine the break position of the lightning conductor. The key to the implementation of 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 level.

[0004] At present, there are two problems in the research of this method: First, the oscillation and tailing time of the incident wave of the pulse signal is long and the waveform is complex. When the line break point is close to the detection point, the oscillation and tailing of the reflected wave and the incident wave are superimposed, making it difficult to analyze the arrival time of the incident wave. Therefore, the traditional single-ended traveling wave ranging method usually has a certain blind spot. Second, due to the use of electromagnetic induction method for traveling wave detection, the spatial magnetic field, uneven wire and bending will add noise signals on the basis of weak induction signals, and changing different detection objects and environments will affect the waveform of the traveling wave voltage and current. Therefore, the use of peak, wavelet analysis, feature point learning and training methods to analyze the arrival time of the traveling wave voltage or current has a certain robustness, resulting in a large deviation 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 of 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 lightning arrester of a wind turbine blade based on a traveling wave electricity method comprises 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 ns level, at least 50MHz bandwidth, 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 a 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 cables of different models, and specifically comprises the following operation 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, select a complete data segment according to 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 once, 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; the electric quantity Q can be calculated by integrating the current I with 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 the discrete quantity is fixed as 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 operation controller, the current data is integrated on the time horizontal axis to calculate the traveling wave power value. By analyzing the sudden change of 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, positive total reflection of voltage and negative total reflection of current occur. 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 of the line to be tested with the original length, it can be determined whether the lightning conductor is broken and where the breakpoint of the lightning conductor 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 with a known length of 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 repaired manually. 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 effective is a complete data segment.

[0021] Preferably, in S3, a low-voltage step voltage signal is given at 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 of a wind turbine blade based on the traveling wave electrical quantity method, which has the following beneficial effects:

[0025] The method for locating the broken point of the lightning conductor of a wind turbine blade based on the traveling wave electrical quantity method can realize efficient, accurate, low-cost, and convenient and flexible detection of the broken position of the lightning conductor. The method can be carried with one hand, enter the interior of the wind turbine, detect the continuity of the lightning conductor at the hub of the wind turbine, and determine the specific position of the broken conductor. After determining the broken position, targeted repairs can be carried out at the specific position, 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 It is a single operation flow chart of the present invention for positioning and measuring the broken point of the lightning arrester 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 integration of the traveling wave current. DETAILED DESCRIPTION

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

[0031] Embodiment 1:

[0032] like Figure 1-Figure 3 As shown in the figure, the method for locating the broken point of the blade lightning arrester of a wind turbine generator based on the traveling wave electricity 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, which requires a response speed of ns level 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 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, and the specific operation steps include the following:

[0033] 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, select a complete data segment according to the longest 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 effective triggering is a complete data segment;

[0034] S2: When the data collected by S1 is incomplete, the data collector is restarted once, 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 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 the discrete quantity is fixed as 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 operation controller, the current data is integrated on the time horizontal axis to calculate the traveling wave power value. By analyzing the sudden change of 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, positive total reflection of voltage and negative total reflection of current occur. 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] The measuring end of the line to be tested is given a low-voltage step voltage signal as an excitation source, and the positive traveling wave current generated on the line to be tested is called the incident wave. When the incident wave encounters a breakpoint during transmission along the line to be tested, the traveling wave will be refracted and reflected. The reverse traveling wave current reflected back is called the reflected wave.

[0040] An adjustable resistor is connected in series before the measuring end of the line to be tested, which is used to reduce the oscillation and tailing amplitude and duration of the incident wave by adjusting the line impedance, and to reduce the detection blind area. If the accuracy of Δt needs to be improved, the time window range of the sudden change of the electric quantity in the case of reflection phenomenon can be further analyzed in combination with the change trend of the traveling wave current waveform to find the arrival moment of the reflected wave, analyze the sudden change of the traveling wave electric quantity, and improve the accuracy, stability and consistency of the detection based on this;

[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 of the line to be tested with the original length, it can be determined whether the lightning conductor is broken and where the breakpoint of the lightning conductor 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 with a known length of 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 of the line to be tested with the original length, it can be determined whether the lightning conductor is broken and where the breakpoint of the lightning conductor is.

[0047] S5: When a break point of the line to be measured is detected, the current break point is repaired manually. 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] Embodiment 2:

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

[0050] S1: A low-voltage step voltage signal is given as the excitation source at the measuring end of the line to be tested, and a positive traveling wave current is generated on the line to be tested, which is called the incident wave. When the incident wave encounters a breakpoint during transmission along the line to be tested, the traveling wave will be refracted and reflected, and the reverse traveling wave current reflected back is called the reflected wave.

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

[0052] S3: Use a high-frequency current transformer to collect the traveling wave current at the measuring end of the line to be tested, then integrate the current data on the time horizontal axis to calculate the traveling wave electric quantity value, and find the time difference Δt of the accurate arrival time of the incident wave and the reflected wave by analyzing the traveling wave electric quantity mutation. If the accuracy needs to be improved, the electric quantity mutation time window range under the 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 electric quantity mutation 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 distance between the breakpoint of the line to be tested and the test point can be calculated.

[0057] Embodiment three:

[0058] A method for locating the broken point of the lightning arrester of a wind turbine blade based on the traveling wave power method, such as Figure 2 As shown in the figure, it is a flow chart of a single location measurement of the broken point of the lightning protection line. After the measurement starts, the rising edge trigger of the data logger is first started, 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 longest 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, data sampled for at least 2us from the effective triggering is a complete data segment.

[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, positive voltage total reflection and negative current total reflection occur, such as 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 line to be tested and the test point can be calculated. By comparing the breakpoint distance and the original length of the line to be tested, 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. By detecting the traveling wave power, it can 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 has very small energy compared to the incident wave and reflected wave, and the small change in the amount of electricity caused can be ignored. It can be automatically filtered out by the algorithm. Only when the continuous amplitude changes significantly beyond a threshold, such as the rise rate>1nc / ns, the fall rate<-2nc / ns, is it considered a mutation. Figure 3 As shown in the picture on the right.

[0062] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for locating the broken point of a lightning arrester of a wind turbine blade based on a traveling wave electric quantity 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 whole 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, which requires a response speed of ns level and at least 50MHz bandwidth, based on the working principle of 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, which specifically includes the following operation steps: 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, select a complete data segment according to 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 once, 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: Q = ∫I(t)dt; The electric quantity Q can be calculated by integrating the current I with 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 the discrete quantity is fixed as 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; Based on the operation controller, the current data is integrated on the time horizontal axis to calculate the traveling wave power value. By analyzing the sudden change of traveling wave power, the time difference Δt of the accurate arrival time of the incident wave and the reflected wave is found. According to the traveling wave theory, when the line end is short-circuited, positive total reflection of voltage and negative total reflection of current occur. 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. S4: Based on the calculated Δt and the known wave velocity V, the calculation formula for the breakpoint 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 of the line to be tested with the original length, it can be determined whether the lightning conductor is broken and where the breakpoint of the lightning conductor is. The traveling wave velocity V of the measured line can be calibrated in advance, that is, Δts is measured in advance through a line with a known length of Ls, and then calculated. The formula is: V = 2 × Ls ÷ Δts; S5: When a break point of the line to be measured is detected, the current break point is repaired manually. 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 the lightning arrester of a wind turbine blade based on the traveling wave electrical quantity method according to claim 1 is 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 effective is a complete data segment.

3. The method for locating the broken point of the lightning arrester of a wind turbine blade based on the traveling wave electrical quantity method according to claim 1 is characterized in that: 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.

4. The method for locating the broken point of the lightning arrester of a wind turbine blade based on the traveling wave electrical quantity method according to claim 1 is characterized in that: The measuring end of the line to be measured is connected in series with an adjustable resistor, which is used 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.

5. The method for locating the broken point of the lightning arrester of a wind turbine blade based on the traveling wave electrical quantity method according to claim 1 is characterized in that: In S3, if the accuracy of Δt needs to be improved, the time window range of the sudden change of the electric quantity 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 sudden change of the traveling wave electric quantity, thereby improving the accuracy, stability and consistency of the detection.

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