WO2017161630A1

WO2017161630A1 - Small-region lightning monitoring and positioning method and system

Info

Publication number: WO2017161630A1
Application number: PCT/CN2016/080286
Authority: WO
Inventors: 梅红伟; 闫石; 王黎明
Original assignee: 清华大学深圳研究生院
Priority date: 2016-03-23
Filing date: 2016-04-26
Publication date: 2017-09-28
Also published as: CN105866558B; CN105866558A

Abstract

A small-region lightning monitoring and positioning method and system. The method comprises the following steps: S1, performing experimental calibration on a function relationship of an output voltage peak value of a lightning current sensor during lightning, a lightning current peak value and a lightning stroke point; S2, setting, within a measured cell, three lightning current sensors; and S3, respectively detecting output voltage peak values of the three lightning current sensors during lightning, and jointly determining the position of the lightning stroke point according to the function relationship.

Description

Small area lightning monitoring and positioning method and system

[Technical Field]

The invention relates to a small area lightning monitoring and positioning method and system.

【Background technique】

Lightning positioning and lightning current parameter monitoring play an important role in lightning characteristics research and lightning protection. The lightning positioning system can provide more technical information for lightning protection, meteorological research, construction and other fields. At present, there are relatively mature lightning monitoring networks all over the world. By monitoring the direction of the magnetic field generated by the lightning current and the time of reaching the sensor, the parameters such as the lightning strike position, the lightning current amplitude and the lightning current polarity can be calculated. The positioning methods of lightning positioning are mainly divided into single station positioning and multi-station positioning. The application is more widely used for multi-station positioning, which can greatly improve the positioning accuracy. Foreign research on lightning current started earlier. Since the 1980s, the National Lightning Detection Network (NLDN) has developed over the years. At present, the detection rate of lightning is more than 80%, and the positioning error is less than 1km. In Europe, the ZEUS lightning monitoring network was established in 2001, and the lightning current positioning function was realized by the time difference method, but the positioning error was large. China's lightning current monitoring system has developed rapidly in recent years. Since 1993, the power system has established a regional lightning current monitoring network in the country, which plays an important role in lightning protection of power systems. The meteorological department detects lightning current. There are more than 100 stations. The positioning error of the XDD03 type lightning detection system researched by the Ministry of Electronics Industry is less than 1km. Chen Jiahong et al. designed and studied the lightning direction detector. By using a set of orthogonal frame antennas, a set of magnetic field signals in the plane is measured, and the original magnetic fields in different directions are obtained by amplification, filtering, integration, etc. The azimuth of the lightning current and the magnitude of its magnetic field, so that the lightning current directional measurement, the direction error is less than 1 °.

The single station positioning method uses the magnetic field orientation technology to analyze the spectral characteristics of lightning current. It is generally only used to monitor high-intensity and long-distance lightning signals. Because of its relatively simple monitoring method, only one sensing device has large dispersion and data error. Larger, resulting in lower accuracy of the azimuth and amplitude monitoring of the monitoring.

The multi-station positioning method uses multiple monitoring stations to monitor the same lightning signal, integrates the measurement results of each monitoring station, and calculates and measures the lightning strike position and lightning parameters of the lightning. Multi-station positioning methods are mainly divided into directional positioning method, time difference positioning method and comprehensive positioning method. The directional positioning method uses the principle of triangulation to monitor the direction of the magnetic field, as shown in Figure 1. When a lightning strike occurs at point A, the azimuth angles α ₁ and α ₂ are measured at DF ₁ and DF ₂ respectively, and the lightning current position can be obtained by the triangulation principle. Since the magnetic field is far away and the direction error is large, the accuracy of the directional positioning method is low.

The principle of time difference method is shown in Fig. 2. In the figure, ABC is the detection station. According to the time difference of the lightning strike signal obtained by the two detection stations AC and the distance between the two stations of the AC, a hyperbola can be obtained, and the lightning strike is located on the hyperbola. a little. Similarly, according to the other two detection stations, BC obtains another hyperbola. The intersection of the two hyperbolas is P, and the other point P' is a mathematically other solution. The P' point can be removed by the fourth detection station. The location where the actual lightning strike occurred. The current time measurement is performed using GPS, and the GPS accuracy generally used is less than 1 us, so the positioning accuracy in the time difference method is 1 km. The time difference method is limited by time accuracy, so positioning accuracy is difficult to improve.

[Summary of the Invention]

In order to overcome the deficiencies of the prior art, the present invention provides a small area lightning monitoring and positioning method and system to improve the accuracy of lightning location in a small range.

A small area lightning monitoring and positioning method includes the following steps:

S1. The experimental calibration of the peak value of the output voltage of the lightning current sensor under lightning is a function of the peak value of the lightning current and the lightning strike point;

S2, setting three of the lightning current sensors in the measured cell;

S3. The output voltage peaks of the three lightning current sensors are respectively detected under lightning, and the position of the lightning strike point is jointly determined according to the function relationship.

Preferably,

The lightning current sensor is an air core coil.

Preferably,

The axes of the three lightning current sensors intersect at the same point.

Preferably,

The function relationship is:

Among them, U _omi represents the peak value of the output voltage of the i-th lightning sensor, I _m represents the peak of the lightning current of the lightning current sensor, k is the coefficient, x _i and y _i represent the coordinates of the i-th lightning sensor, and x and y represent the lightning strike point. coordinate of.

Preferably,

The axes of the three lightning current sensors are 120° between the two.

Preferably,

According to the function relationship, a nonlinear equation set with respect to x, y, I _m can be obtained, and the least squares solution of the nonlinear equations is iteratively obtained by using the Newton-Raphson method. If x, y, I _m converge, Then, it is determined that the location of the lightning is located in the measured cell, and if x, y, _Im does not converge, it is determined that the location of the lightning is outside the measured cell.

Preferably,

The lightning current direction and the lightning current polarity are determined according to the voltage polarities of the three lightning current sensors.

The invention also provides a community lightning monitoring and positioning system, comprising: a first lightning sensor, a second lightning sensor, a third lightning sensor, a first data acquisition card, a first fiber module, a second data acquisition card, and a second fiber a module, a third data acquisition card, a third fiber optic module, and a solar power generation device, the first data acquisition card is configured to collect an output voltage of the first lightning sensor, and the second data acquisition card is configured to acquire a second lightning sensor Outputting a voltage, the third data acquisition card is configured to collect an output voltage of the third lightning sensor, the first fiber module sends data collected by the first data acquisition module to the optical fiber, and the second optical fiber module uses the second data The data collected by the acquisition card is sent to the optical fiber, and the third optical fiber module sends the data collected by the third data acquisition card to the optical fiber, where the solar power generation device is used for the first data acquisition card, the first optical fiber module, and the first The second data acquisition card, the second optical fiber module, the third data acquisition card, and the third optical fiber module are powered.

Preferably,

The first lightning sensor, the second lightning sensor and the third lightning sensor lightning current sensor are air-core coils.

Preferably,

The axes of the first lightning sensor, the second lightning sensor, and the third lightning sensor intersect at the same point.

Preferably,

The axes of the first lightning sensor, the second lightning sensor and the third lightning sensor are 120° between the two.

The beneficial effects of the invention are:

1) The numerical positioning method can avoid the accuracy limitation of the direction and time measurement of the magnetic field by the orientation method and the time difference method. The positioning accuracy of the method mainly depends on the measurement accuracy of the sensor amplitude, which can greatly improve the lightning current positioning accuracy and narrow the measurement range. .

2) A scheme for solving the lightning current localization problem using numerical analysis method is proposed. In the solution, the optimization problem can be further considered and the measurement accuracy can be improved. It is also possible to increase the number of sensors in large stations to further improve measurement accuracy.

3) The use of special lightning current sensor and the current advanced data acquisition and data transmission system ensure the reliability of signal transmission, and the whole measurement system uses solar energy to supply, the system is independent and stable, free from maintenance, and reduces labor costs. Increased system usability.

[Description of the Drawings]

1 is a schematic diagram of an orientation method for positioning lightning in the prior art

2 is a schematic diagram of a time difference method for positioning lightning in the prior art

FIG. 3 is a schematic diagram of a method for monitoring and positioning a mine lightning according to an embodiment of the present invention; FIG.

4 is a diagram of a mine lightning monitoring and positioning system according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a method for monitoring and positioning a mine lightning according to an embodiment of the present invention; FIG.

【detailed description】

Preferred embodiments of the invention are described in further detail below.

As shown in FIG. 3 , a schematic diagram of a method for monitoring and locating a mine lightning monitoring according to an embodiment. In this embodiment, a self-made lightning current sensor is used to calibrate the response characteristics of the cell to obtain an output voltage and a current amplitude and a measuring distance. Relationship between three lightning currents by using different locations The sensor, the three sets of measurement data obtained by the same lightning current, can obtain the lightning current amplitude and plane coordinate by solving the equations. The lightning current sensor can adopt an air-core coil, and the three coils are placed in the same direction at the edge of the measured area, and the axes of the air-core coils are at an angle of 120°, which ensures that the lightning current of each measurement system is high for each position. Sensitivity.

Taking coil A as an example, analysis is performed using a Cartesian coordinate system as shown in FIG. The coordinates of the coil A, the coil B, and the coil C are (x ₁ , y ₁ ), (x ₂ , y ₂ ), (x ₃ , y ₃ ), and the lightning strike point coordinates are (x, y). It is assumed that the lightning current enters the ground vertically at the lightning strike point and is the negative lightning current. The peak value of the lightning current is I _m . The magnetic induction intensity B generated by the lightning strike point at the coil A can be decomposed into a vertical component B ₁ and a horizontal component B ₂ at the coil, and the horizontal component is not parallel to the coil, and no induced voltage is generated at the coil. The output voltage is dominated by the vertical component. get:

B ₁ =Bcosθ(1)

The lightning current sensor is calibrated in the laboratory. When the direction of the magnetic field is perpendicular to the plane of the coil, the relationship between the peak value U _{om of} the output voltage and the peak value I _{m of the} current and the distance r from the lightning current is:

According to Biot-Savar's law, the magnetic field generated by the current is proportional to the current intensity, so the peak value of the coil output voltage can be obtained as:

Similarly, for three coils, the relationship between the output voltage and the lightning current peak and lightning point coordinates is:

Among them, the output voltage peak value U _{om of the} three coils can be measured by an oscilloscope and is a known quantity. Therefore, the nonlinear equations of x, y, and I _m can be obtained. The Newton-Raphson method is used to iteratively find the least squares solution to obtain the lightning current position and the lightning current amplitude.

The system of equations can be expressed as:

Its Jacobian matrix can be expressed as:

Using the Newton-Raphson method to iterate, since only the lightning current can start the sensor signal, the initial value of the lightning current cannot be 0. Otherwise, the Jacobian matrix is irreversible and cannot be solved. Therefore, given the initial value [x, y, I _m ] ⁰ = [ ^{0, 0} , 10], in order to improve the accuracy, the lightning current unit is kA. Bring it into the equations to get [F ₁ , F ₂ , F ₃ ] ⁰ , bring in the Jacobian matrix to get J ⁰ , and solve the modified equation:

Δx, Δy, ΔI _m are obtained, and the above calculation is repeated by calculating a new [x, y, I _m ] ¹ using the following formula.

The convergence indicator is:

When the absolute values of the finally obtained variables Δx, Δy, ΔI _m are all less than 0.1, the calculation is terminated, and the required accuracy is reached. The [x, y, I _m ] ⁿ obtained in the previous step is the final result. .

When using the Newton-Raphson method for lightning location, the initial value problem needs to be considered. If the initial value is closer to the true value, it can converge to the vicinity of the true value faster, otherwise the divergence may occur or converge to other values. Therefore, when iterating, the initial value [x, y, I _m ] ⁰ = [ ^{0, 0} , 10] is given for solving. According to Figure 3, the origin (0,0) can be considered to be located at the center of the three coils, so the initial value of (x, y) can be selected to ensure that the solution results in the small area monitored.

Therefore, the lightning location results are classified according to the calculation results. When the calculation result converges, according to the initial value selection, the positioning result should be inside the monitored area, and the calculated position and amplitude result of the lightning is the final result.

When the calculation result does not converge, the detected lightning is located outside the monitored area, so the lightning position can be judged according to the polarity and magnitude of the lightning current detected by the three sensors. At this time, due to the divergence of the solution result, the lightning current amplitude cannot be given.

The lightning position is shown in Figure 5. The mid-perpendicular line of the three coils divides the monitored area into seven parts. Since the three coils need to be in the positive direction when installed (when the coil is in a magnetic field environment, the voltage generated by the coil is opposite to the direction of the magnetic field, then the direction of the coil is positive, and if the voltage generated by the coil is the same as the direction of the magnetic field, then The direction of the coil is negative (clockwise) (ie, the coil C is wound around the origin O by 120° and then coincides with the coil B, and continues to wrap around the coil A after 120°). When the lightning is located on the vertical line in the coil, the lightning current is generated. The direction of the magnetic field is parallel to the coil when passing through the coil, and no magnetic flux is generated, so the coil cannot measure the lightning current. When the lightning strike point is at the intersection of two mid-perpendicular lines, only one coil can measure the lightning current signal, and the lightning position can also be judged accordingly.

The lightning current has opposite polarity on both sides of the vertical line, so the lightning current position can be judged according to the polarity of the three coils. The lightning current coil is placed clockwise in the same direction, and the lightning current can be divided into positive polarity and negative polarity, so Judging the magnitude of the absolute value of the amplitude detected, the polarity of the lightning current can be judged, and the judgment basis is as shown in Table 1.

Table 1 orientation table

The brackets next to the polarity in the table indicate the absolute value of the measured value. For example, when the measurement results of coil A, coil B, and coil C (the polarity in the table refers to the polarity of the voltage) are positive, positive, and negative, respectively, If the negative absolute value is large, the lightning current direction is positive north, and the lightning current polarity is negative; if the negative absolute value is small, it is judged that the lightning current direction is positive south and the lightning current polarity is negative. All other cases have corresponding controls in the table.

Since the lightning current is outside the monitored area when it is unable to converge, there is no influence on the lightning parameter monitoring in a small area. According to the azimuth statistics, it can be judged which side of the monitoring area has more mines, and it is necessary to focus on strengthening protection measures.

Due to the limited accuracy of the current GPS clock, the time difference method can only ensure that the positioning accuracy is on the order of 1 km. However, the positioning method of the present invention only needs to ensure the measurement accuracy of the sensor, and does not need to be unified of the clock, so the positioning range can be greatly reduced. The positioning method can be applied to small-scale localization of lightning current, and realizes a small-scale lightning warning and protection function similar to a gas station, a substation, and an oil field station.

Since the coil is an air-core coil, it is guaranteed to measure a large amplitude of lightning current. In order to ensure its sensitivity, a larger diameter and number of turns are required. In one embodiment, the air-core coil has a diameter of 60 cm, a length of 20 cm, a number of turns of 50, and is wound using a 2 x 3 mm flat copper wire. According to the actual parameter test, the lower limit cutoff frequency of the coil is 112 Hz, and the upper limit cutoff frequency is several tens of MHz, which can cover the frequency range of the lightning current. The coil is made of epoxy resin as a skeleton, and a subway shell is additionally arranged outside the coil for shielding, and a magnetic circuit of the iron box is cut laterally on the iron shell, and the longitudinal groove is prevented from circulating. The components such as the matching resistor and the coil are cast into a whole by epoxy, and the functions of waterproofing and sunscreen are achieved. The final coil has an outer dimension of 70×70×24 cm, as shown in FIG. 4, and the cable joint is recessed.

When the magnetic field is perpendicular to the plane of the coil, the fitting formula of the output voltage peak U _om and the current peak I _m and distance r is:

The variables in the formula are all international standard units. In order to ensure the calculation accuracy, and the lightning current amplitude is generally above 10kA, the current unit can be replaced by kA. The formula is:

A lightning current monitoring system is installed at a designated location in the required monitoring area, and a voltage signal of the lightning current waveform is obtained by sensing a rapidly changing magnetic field generated by a lightning current falling within the station or near the station.

As shown in FIG. 4, a cell lightning monitoring and positioning system of an embodiment includes a lightning sensor, a data acquisition card, a fiber transmission module, a fiber receiving module, a computer, and a solar power generation system, wherein the lightning sensor comprises: a first lightning sensor A, The second lightning sensor B and the third lightning sensor C, the lightning sensor, the data acquisition card, the fiber transmission module, and the solar power generation system are outdoor parts.

For the branch of the first lightning sensor A, the data acquisition card is connected to the first lightning sensor A through a cable for collecting the output voltage of the first lightning sensor A, and the fiber sending module is used for collecting the data acquisition card. The output voltage data is sent to the fiber receiving module through the optical fiber, and the computer reads the output voltage data received by the fiber receiving module and performs calculation. Similarly, the two branches of the second lightning sensor B and the third lightning sensor C are the same as the first lightning sensor A.

The sampling signal is collected by the acquisition card, and the optical fiber module is converted into an optical signal and transmitted to the control room through the optical fiber, and the control room is converted into an electrical digital signal input computer through the optical fiber module. Among them, the waveform data obtained by the three sensors are respectively input into three computers, thereby ensuring the independence and immediacy of the three measurement systems, and then uploading them to a computer for processing using the monitoring software to obtain the required data.

The solar power generation device is used to supply power to the data acquisition card and the fiber transmission module to prevent lightning current interference from entering the power system. Due to the short duration of lightning current, the data acquisition card can use USB-5133 high-speed acquisition card for data acquisition, and its sampling rate can reach 100M/s. Due to mine When the current occurs, a strong electromagnetic field is generated. To prevent the signal from being disturbed during transmission, the signal transmission part uses optical fiber for transmission.

The above is a further detailed description of the present invention in connection with the specific preferred embodiments, and the specific embodiments of the present invention are not limited to the description. For those skilled in the art to which the present invention pertains, a number of simple derivations or substitutions may be made without departing from the inventive concept, and should be considered as belonging to the invention as defined by the appended claims. protected range.

Claims

A small area lightning monitoring and positioning method, characterized in that the method comprises the following steps:

S1. The experimental calibration of the peak value of the output voltage of the lightning current sensor under lightning is a function of the peak value of the lightning current and the lightning strike point;

S2, setting three of the lightning current sensors in the measured cell;

S3. The output voltage peaks of the three lightning current sensors are respectively detected under lightning, and the position of the lightning strike point is jointly determined according to the function relationship.
The small area lightning monitoring and positioning method according to claim 1, wherein:

The lightning current sensor is an air core coil.
The small area lightning monitoring and positioning method according to claim 2, wherein

The axes of the three lightning current sensors intersect at the same point.
The small area lightning monitoring and positioning method according to claim 3, wherein the function relationship is:

Among them, U omi represents the peak value of the output voltage of the i-th lightning sensor, I m represents the peak of the lightning current of the lightning current sensor, k is the coefficient, x i and y i represent the coordinates of the i-th lightning sensor, and x and y represent the lightning strike point. coordinate of.
The small area lightning monitoring and positioning method according to claim 3, wherein

The axes of the three lightning current sensors are 120° between the two.
A small area lightning monitoring and positioning method according to claim 5, wherein

According to the function relationship, a nonlinear equation set with respect to x, y, I m can be obtained, and the least squares solution of the nonlinear equations is iteratively obtained by using the Newton-Raphson method. If x, y, I m converge, Then, it is determined that the location of the lightning is located in the measured cell, and if x, y, Im does not converge, it is determined that the location of the lightning is outside the measured cell.
A small area lightning monitoring and positioning method according to claim 5, wherein

The lightning current direction and the lightning current polarity are determined according to the voltage polarities of the three lightning current sensors.
A community lightning monitoring and positioning system, comprising: a first lightning sensor, a second lightning sensor, a third lightning sensor, a first data acquisition card, a first fiber module, and a first a data acquisition card, a second fiber module, a third data acquisition card, a third fiber module, and a solar power generation device, wherein the first data acquisition card is configured to collect an output voltage of the first lightning sensor, and the second data acquisition card The third data acquisition card is configured to collect an output voltage of the third lightning sensor, and the first fiber optic module sends the data collected by the first data acquisition module to the optical fiber, The second fiber optic module sends the data collected by the second data acquisition card to the optical fiber, and the third fiber optic module sends the data collected by the third data acquisition card to the optical fiber, where the solar power generation device is configured to collect the first data. The card, the first fiber module, the second data acquisition card, the second fiber module, the third data acquisition card, and the third fiber module are powered.
A small area lightning monitoring and positioning system according to claim 8, wherein:

The first lightning sensor, the second lightning sensor and the third lightning sensor lightning current sensor are air-core coils.
A small area lightning monitoring and positioning system according to claim 9, wherein:

The axes of the first lightning sensor, the second lightning sensor, and the third lightning sensor intersect at the same point.