Forest standing tree lightning strike attachment point test system and lightning strike attachment point distribution characteristic test and analysis method

Abstract

The application discloses a forest standing tree lightning stroke attachment point test system and a lightning stroke attachment point distribution characteristic test and analysis method. The test system comprises a lightning pulse source, a sample forest standing tree, a lightning pulse source control and lightning pulse measurement and analysis unit, an arc injection clamping mechanism and adjustment unit, and a lightning stroke attachment process monitoring unit. The lightning stroke attachment point analysis method is to use a data statistical method, observe the results of the lightning stroke process monitoring unit, and comprehensively statistically analyze the attachment point distribution characteristics through artificial observation, so that the correlation between the standing tree lightning stroke attachment and factors such as the water content of the standing tree sample and the arc injection gap distance is finally obtained, a lightning stroke attachment point database simulating the lightning stroke fire characteristics of forests with different regional characteristics is formed, and a foundation is laid for the research on the multi-physical field modeling of forest combustible lightning stroke, the lightning stroke fire mechanism and the prediction algorithm.

Description

Technical Field

[0001] This invention pertains to forest lightning strike testing technology, specifically to test methods for the characteristics of lightning strike fire adhesion in forests and techniques for testing the laws governing lightning adhesion. In particular, it relates to a test system for lightning adhesion points on standing trees in forests, as well as a test and analysis method for the distribution characteristics of lightning adhesion points. Background Technology

[0002] Lightning is a multiple, continuous, time-series discharge process. In this process, the first lightning strike plays a crucial role, involving the adhesion process between the lightning strike and flammable materials such as forest vegetation and standing trees. It directly affects the lightning current shunting characteristics in these materials, and is therefore of great significance for theoretical research on the smoldering or ignition mechanisms of forest lightning strikes. Existing research on lightning-induced fires mainly relies on predictive models built from historical lightning-induced fire data, predicting the probability and location of lightning-induced fires based on meteorological conditions and forest conditions. There are very few reports in the literature that study the generation process of lightning-induced fires from the perspective of physical processes or mechanisms. Therefore, the accuracy of such predictive models for lightning strike early warning is difficult to guarantee. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a test system for lightning strike attachment points on standing trees in forests, as well as a test and analysis method for the distribution characteristics of lightning strike attachment points, laying the foundation for the research on multi-physics field modeling of lightning strikes on forest combustibles, the mechanism of lightning fires, and prediction algorithms.

[0004] This invention is achieved through the following technical solution:

[0005] A test system for lightning attachment points of standing trees in forests includes a lightning pulse source, a sample forest standing tree, a lightning pulse source control and lightning pulse measurement and analysis unit, an arc injection clamping mechanism and adjustment unit, and a lightning attachment process monitoring unit.

[0006] The lightning pulse source includes a controllable high-voltage DC charging power supply and a lightning pulse generating unit for generating lightning pulse waves; the charging voltage of the controllable high-voltage DC charging power supply to the lightning pulse generating unit is monitored online by a charging voltage monitoring sensor, and the analog charging voltage is transmitted to the control unit of the lightning pulse source control and lightning pulse measurement and analysis unit.

[0007] The sample forest trees are clamped using an arc injection clamping mechanism and an adjustment unit. This mechanism and unit inject a lightning arc into the sample forest trees and adjust the gap between the injected arc and the sample forest trees.

[0008] The lightning pulse source control and lightning pulse measurement and analysis unit consists of a control unit and a lightning pulse measurement and analysis unit, and is used to realize the control of the lightning strike attachment point test and the measurement and analysis of lightning pulse parameters;

[0009] The lightning strike attachment process monitoring unit includes a high-speed camera monitoring instrument and a high-speed camera control computer, used to obtain the arc generation and development process of the lightning strike attachment process.

[0010] Furthermore, the controllable high-voltage DC charging power supply adopts a voltage multiplier charging method, consisting of an electronically controlled voltage regulator T1, a transformer T2, and a voltage multiplier capacitor C. B It consists of rectifier silicon stack D1, rectifier silicon stack D2, and current-limiting resistor Rc.

[0011] Furthermore, the lightning pulse generating unit consists of a main pulse energy storage capacitor. C 1. High-voltage discharge switch G, waveform forming resistor R1, waveform forming resistor R 2 and the formation of capacitance C The sample forest standing trees are connected to the output end of the lightning pulse generation unit via an electric arc injection clamping mechanism and adjustment unit.

[0012] Furthermore, the high-voltage discharge switch G includes a high-voltage electrode and a low-voltage electrode sealed in an insulating shell. The high-voltage electrode extends from the top of the insulating shell to a terminal, and the low-voltage electrode extends from the top of the insulating shell to a terminal. A bellows telescopic mechanism is sleeved on the outside of the low-voltage electrode. The position of the low-voltage electrode is adjusted by the bellows telescopic mechanism to adjust the anti-electric gap.

[0013] Furthermore, the air pressure inside the insulating outer shell is 2×10⁻⁶. 5 Pa -5×10 5 Pa, an insulating outer jacket with an umbrella-shaped structure is provided on the outside of the insulating outer shell.

[0014] Furthermore, the control unit includes a charging voltage monitoring circuit, a programmable controller and related control circuits. The charging voltage monitoring circuit of the control unit receives the signal transmitted from the charging voltage monitoring sensor and processes it through the programmable controller and related control circuits to control the discharge of the high-voltage discharge switch G of the lightning pulse generating unit.

[0015] The lightning pulse measurement and analysis unit includes a pulse voltage sensor, a pulse current sensor, a digital oscilloscope, and an industrial control computer. The pulse voltage sensor, pulse current sensor, and array oscilloscope work together to measure the lightning voltage between the lightning arc injection point and the low-voltage end of the standing tree, as well as the lightning current flowing through the tree. The industrial control computer processes and analyzes the pulse voltage and pulse current signals measured by the oscilloscope to obtain the lightning voltage under parameters including standing tree parameters, ambient temperature and humidity, and arc injection gap distance.U Lightning current I The industrial control computer, together with the programmable logic controller and its related control circuits, controls the connection / disconnection of the charging process, the rise / fall of the high voltage, and the adjustment of the gap distance of the high voltage discharge switch G in the forest standing tree attachment characteristic test, so as to realize the automatic control of the test process of forest standing tree lightning strike attachment point.

[0016] Furthermore, the arc injection clamping mechanism and adjustment unit includes a clamp and adjustment mechanism and an electrode adjustment mechanism; the clamp and adjustment mechanism includes a sample forest tree fixing clamp mounted on a metal plate, with the bottom end face of the tree in close contact with the metal plate; the electrode adjustment mechanism includes a pair of metal electrodes and an electrode gap distance adjustment mechanism, the metal electrodes including a high-voltage injection electrode and a return electrode, the high-voltage end of the lightning pulse source is connected to the high-voltage injection electrode, and the end face of the high-voltage injection electrode is in a certain gap distance with the end face of the sample forest tree; the low-voltage end of the lightning pulse source is connected to the return electrode, and the return electrode is connected to the metal mounting plate; the electrode gap distance adjustment mechanism is a lifting mechanism set on one side, the high-voltage injection electrode is mounted on the lifting mechanism, and the height of the high-voltage injection electrode is adjusted by the lifting mechanism, thereby adjusting the gap distance between the high-voltage injection electrode and the end face of the sample forest tree.

[0017] Furthermore, the high-pressure injection electrode is an electrode with a rounded end or a pointed tip, and the distance between the high-pressure injection electrode and the end face of the forest tree sample can be adjusted from 1mm to 100mm or even greater.

[0018] A test and analysis method for the distribution characteristics of lightning strike attachment points on standing trees in forests includes the following steps:

[0019] 1) Sample selection and treatment: Select forest standing tree samples from typical forest areas and treat the samples to prepare multiple standing tree samples with different moisture contents;

[0020] 2) Electrically connect the arc injection clamping mechanism and adjustment unit to the lightning pulse generation unit, install the forest standing tree in the clamping mechanism, fix the position and gap distance between the high voltage injection electrode and the end face of the sample forest standing tree, apply lightning pulse waves of different intensities, and obtain the relationship between the lightning attachment process and the lightning pulse parameters through the lightning attachment process monitoring unit.

[0021] 3) Adjust the position and gap distance between the high-voltage injection electrode and the end face of the forest standing tree sample, apply lightning pulse waves of different intensities, and obtain the correlation between lightning adhesion characteristics and arc injection gap distance through the lightning adhesion process monitoring unit.

[0022] 4) Lightning strike tests were conducted on the first sample at different arc injection gap distances D1 to D5. The discharge voltage was gradually increased at each arc injection gap distance until arc discharge could occur.

[0023] 5) Repeat steps 2) to 5) until all standing tree specimens have undergone lightning strike adhesion tests; establish a correlation database between forest standing tree lightning adhesion and multiple factors such as standing tree moisture content, lightning current parameters, and arc injection gap distance, and obtain an evaluation method for the distribution characteristics of forest standing tree lightning adhesion.

[0024] 6) Statistical analysis was performed on all lightning strike test results to obtain the correlation between lightning-induced adhesion on standing trees and the moisture content of the standing tree sample and the arc injection gap distance factor, thus forming the distribution characteristics of lightning-induced adhesion on standing trees.

[0025] Furthermore, statistical analysis was conducted on the lightning strike test results, including research on the characteristics and influencing factors of lightning strike attachment points on standing trees. This included adjusting the gap distance between the arc injection electrode and the end face of the sample forest standing tree, applying lightning pulse waves of different intensities, and obtaining the lightning attachment process and the attachment area of ​​lightning on the end face of the sample forest standing tree through the lightning attachment process monitoring unit. The analysis of the lightning attachment points on the forest standing trees was conducted, and a correlation database between lightning attachment on forest standing trees and multiple factors was established through experiments. A multi-factor regression method was used to obtain an evaluation method for the distribution characteristics of lightning attachment on forest standing trees.

[0026] This invention establishes a test system for lightning-induced attachment points on standing trees in forests and proposes a test method for these points. Through observations from a lightning strike monitoring unit and combined with manual observation, the distribution characteristics of attachment points are statistically analyzed. This results in the correlation between lightning-induced attachment points and factors such as the moisture content of the standing tree sample and the distance of the arc injection gap. A database of lightning-induced attachment points simulating forest lightning fire characteristics in different geographical regions is formed. The correlation between lightning-induced attachment characteristics and lightning electrical parameters, action conditions, and the natural and ecological characteristics of the standing trees is obtained. The distribution law of lightning-induced attachment on standing trees in forests is determined, providing the initial distribution state of arc injection for multiphysics modeling and calculation of the ignition mechanism of lightning-induced standing trees. This lays the foundation for research on multiphysics modeling of forest combustibles by lightning, lightning fire mechanisms, and prediction algorithms. Attached Figure Description

[0027] Figure 1 This is a structural block diagram of the forest standing tree lightning attachment point test system of the present invention;

[0028] Figure 2 This is a circuit diagram of the forest standing tree lightning attachment point test system of the present invention;

[0029] Figure 3 This is a structural block diagram of the high-voltage discharge switch G of the present invention;

[0030] Figure 4 This is a structural diagram of the arc injection clamping mechanism and adjustment unit of the present invention;

[0031] (a) is a top view, and (b) is a perspective view.

[0032] Figure 5 A flowchart for the experimental and analytical methods of lightning strike attachment point distribution characteristics of standing trees in forests. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0034] See Figure 1 and Figure 2 As shown, the forest standing tree lightning attachment point test system of the present invention consists of a lightning pulse source 1, a sample forest standing tree 2, a lightning pulse source control and lightning pulse measurement and analysis unit 3, an arc injection clamping mechanism and adjustment unit, and a lightning attachment process monitoring unit 4.

[0035] The lightning pulse source 1 mainly consists of a controllable high-voltage DC charging power supply 1-1 and a lightning pulse generating unit 1-2. In actual testing, the charging voltage of the controllable high-voltage DC charging power supply 1-1 to the lightning pulse generating unit 1-2 is monitored online by a charging voltage monitoring sensor 1-3, and the analog charging voltage is transmitted to the control unit 31 of the lightning pulse source control and lightning pulse measurement and analysis unit 3. The function of the lightning pulse generating unit 1-2 is to generate lightning pulse waves.

[0036] The function of the lightning pulse source control and lightning pulse measurement and analysis unit 3 is to control the lightning strike attachment point test and measure and analyze the lightning pulse parameters. It mainly consists of a control unit 31 and a lightning pulse measurement and analysis unit 32. The control unit 31 mainly consists of a charging voltage monitoring circuit 31-1 and a programmable logic controller (PLC) and its related control circuits 31-2. The charging voltage monitoring circuit 31-1 of the control unit 31 receives the signal transmitted from the charging voltage monitoring sensor 1-3, and after processing by the PLC and its related control circuits 31-2, it can output a control signal to the PLC and its related control circuits 31-2, thereby controlling the discharge of the high-voltage discharge switch G of the lightning pulse generation unit 1-2. Furthermore, the PLC and its related control circuits 31-2, in conjunction with the industrial control computer 32-4 of the lightning pulse measurement and analysis unit 32, control the connection / disconnection of the charging process, the rise / fall of the high voltage, and the adjustment of the gap distance of the high-voltage discharge switch G in the forest standing tree attachment characteristic test, realizing the automatic control of the forest standing tree lightning strike attachment point test process.

[0037] The lightning pulse measurement and analysis unit 32 is used to control the lightning strike attachment point test and measure and analyze lightning pulse parameters, thus realizing the process control of the forest standing tree attachment characteristic test and the measurement and analysis of lightning parameters. The lightning pulse measurement and analysis unit 32 mainly consists of a pulse voltage sensor 32-1, a pulse current sensor 32-2, a digital oscilloscope 32-3, and an industrial control computer 32-4. The pulse voltage sensor 32-1 and pulse current sensor 32-2, in conjunction with the array oscilloscope 32-3, measure the lightning voltage between the lightning arc injection point of the standing tree and the low-voltage end of the standing tree, as well as the lightning current flowing through the standing tree. The industrial control computer 32-4 processes and analyzes the pulse voltage and pulse current signals measured by the oscilloscope to obtain the lightning voltage under parameters including standing tree parameters, ambient temperature and humidity, and arc injection gap distance. U Lightning current I .

[0038] The lightning strike attachment process monitoring unit 4 observes the generation and development of the electric arc during the lightning strike attachment process. It mainly consists of a high-speed camera monitoring instrument 41-1 and a high-speed camera control computer 41-2. The main function of the high-speed camera monitoring instrument 41-1 is to observe the lightning strike process on the standing tree. Its imaging process is controlled by the high-speed camera control computer 41-2. The lightning strike attachment process of the lightning-struck standing tree is obtained through the lightning strike attachment process monitoring unit 4.

[0039] See Figure 2 This invention presents the principle circuit of the lightning pulse source 1 for testing the lightning adhesion characteristics of standing trees in forests. It mainly comprises two parts: a controllable high-voltage DC charging power supply 1-1 and a lightning pulse generation unit 1-2. Given the extremely high amplitude and high voltage environment during actual lightning strikes, the operating voltage of the lightning pulse power supply in this application cannot be too low, at least not lower than 300kV. Therefore, the controllable high-voltage DC charging power supply 1-1 adopts a voltage doubling charging method to avoid corona discharge during the experiment, which would affect the reliability and stability of the lightning pulse source.

[0040] The controllable high-voltage DC charging power supply 1-1 mainly consists of an electronically controlled voltage regulator T1, a transformer T2, and a voltage multiplier capacitor C. B It consists of rectifier silicon stacks D1 and D2 and current-limiting resistor Rc.

[0041] To address the poor synchronization of discharges in traditional high-voltage discharge MARX generation circuits with multiple discharge switches, and to increase the stability of lightning pulse source discharges, this invention employs a method where an energy storage capacitor discharges directly through a single discharge switch. The lightning pulse generation unit 1-2 mainly consists of a main pulse energy storage capacitor. C 1. High-voltage discharge switch G, waveform forming resistor R1 and R 2 and the formation of capacitance CThe system consists of two components that are electrically connected in series and parallel, with the sample forest trees and their connecting clamps connected in parallel to the output terminals of the lightning pulse generation unit 1-2.

[0042] See Figure 3 The diagram shows the structural block of the high-voltage discharge switch G of the present invention. The high-voltage discharge switch G is a structure that seals a high-voltage electrode a2 and a low-voltage electrode a3 within an insulating shell a1. The high-voltage electrode a2 extends from the top of the insulating shell a1 to form a terminal, and the low-voltage electrode a3 extends from the bottom of the insulating shell a1 to form a terminal. A bellows telescopic mechanism is fitted around the low-voltage electrode a3. The bellows telescopic mechanism includes a bellows a4 and a low-voltage electrode driving mechanism. The low-voltage electrode is sealed to the interior of the insulating shell a1 through the bellows. The low-voltage electrode driving mechanism can be a telescopic motor or a cylinder, etc., to drive the low-voltage electrode to move within the insulating shell a1.

[0043] The high-voltage discharge switch G is a high-voltage, high-current controllable discharge switch operating in a high-pressure environment. The DC withstand voltage of the discharge switch is not less than 1.3 times the rated voltage of the system. Based on a rated system voltage of 300kV, the DC withstand voltage of the discharge switch is 400kV. For discharge switches operating in high-pressure environments, their internal insulation can withstand 2-5×10... 5 The high air pressure of Pa is achieved; for external insulation, the present invention designs an insulating jacket a5 with an external umbrella skirt structure to improve the surface withstand voltage of the external insulating shell a1 of the high voltage discharge switch G.

[0044] The high-voltage, high-current discharge switch can also operate at 10 -1 In a vacuum environment of Pa, the internal insulation of the discharge switch can also be solved. To meet the requirement of reliable operation of lightning pulse generating units of different voltage levels, the low-voltage electrode a3 of the high-voltage discharge switch in the sealed environment is equipped with a bellows telescopic mechanism with adjustable discharge gap distance.

[0045] To improve the reliability and credibility of data on lightning adhesion characteristics of standing trees in forests under repeated lightning strikes, the expected pulse discharge current of the lightning pulse discharge power supply when the standing tree undergoes breakdown discharge should not be too large, and its maximum pulse current peak value should be limited to the range of hundreds of amperes to several kiloamperes.

[0046] See Figure 4As shown, the arc injection clamping mechanism and adjustment unit are used to clamp the sample forest standing trees, realize the arc injection of lightning arc into the sample forest standing trees, and adjust the gap distance between the arc injection and the sample forest standing trees. It mainly consists of the arc injection electrode mechanism and the arc injection electrode gap distance adjustment mechanism. By adjusting the gap distance, the correlation between the arc injection gap distance and the distribution of lightning attachment points is established, thereby laying the foundation for predicting the lightning attachment point database of forest lightning fire characteristics for different regional characteristics.

[0047] The arc injection clamping mechanism and adjustment unit mainly consists of a clamp and adjustment mechanism and an electrode adjustment mechanism. Its function is to fix the sample forest standing tree 2. The clamp and adjustment mechanism is a quadrilateral clamp b2 with adjustable locking position mounted on a metal plate b1. The quadrilateral clamp b2 consists of four stops connected by bolts. By adjusting the installation position of each stop, the clamping of standing trees of different diameters can be achieved, and the bottom end face of the standing tree is in close contact with the metal plate. The electrode adjustment mechanism consists of a pair of metal electrodes and an electrode gap distance adjustment mechanism. The metal electrode includes a high-voltage injection electrode b3 and a return electrode. Its function is to connect the standing timber sample to the lightning pulse source circuit. The high-voltage end of the lightning pulse source is connected to the high-voltage injection electrode of the arc injection clamping mechanism. The high-voltage injection electrode is an electrode with a rounded or pointed end, and its end face has a certain gap distance with the end face of the standing timber sample. The electrode gap distance adjustment mechanism is a lifting mechanism located on one side. The high-voltage injection electrode is mounted on the lifting mechanism. Adjusting the height of the high-voltage injection electrode through the lifting mechanism adjusts the gap distance between the high-voltage injection electrode and the end face of the standing timber sample. The lifting mechanism can be a hydraulic lifting mechanism, a motor-driven screw lifting mechanism, or a cylinder-driven pneumatic lifting mechanism.

[0048] The low-voltage end of the lightning pulse source is connected to the return electrode of the electrode structure. In actual implementation, the metal mounting plate can also serve as the return electrode. That is, the low-voltage end of the lightning pulse source can be directly connected to the metal mounting plate. In order to ensure the uniformity of the current distribution of the lightning strike on the tree, the four connection terminals b4 of the metal mounting plate can be connected to the low-voltage end of the lightning pulse source respectively.

[0049] The distance between the lightning arc injection electrode and the end face of the sample forest tree 2 can be adjusted automatically or manually, and the adjustment range can be 1mm-100mm or even larger.

[0050] See Figure 5 Experimental and analytical methods for the distribution characteristics of lightning strike attachment points on standing trees in forests. The specific experimental and analytical procedures are as follows:

[0051] 1) Sample selection and treatment: Select standing tree samples from forests with typical forest areas and treat the samples, including humidity and moisture content, to simulate the actual environment of different plants under different seasons and climatic conditions. Prepare standing tree samples with different moisture contents, at least 5 samples with different moisture contents (denoted as S1 to S5). The samples can be selected from typical forests with different climatic characteristics (such as the Greater Khingan Mountains, Liangzhou, etc.).

[0052] 2) Electrically connect the arc injection clamping mechanism and adjustment unit to the lightning pulse generation unit of the lightning pulse source. Install the forest standing tree in the clamping mechanism, and then electrically connect the arc injection clamping mechanism and adjustment unit to the lightning pulse generation unit of the lightning pulse source. Fix the position and gap distance between the arc injection and the end face of the sample forest standing tree, apply lightning pulse waves of different intensities, and obtain the relationship between the lightning attachment process and the lightning pulse parameters through the lightning strike attachment process monitoring unit. Select at least 5 arc injection gap distances, with the arc injection distance range covering 10mm-100mm or even larger.

[0053] 3) The position and gap distance between the electric arc injection and the end face of the standing trees in the forest sample were measured. Lightning pulse waves of different intensities were applied, and the correlation between the lightning adhesion characteristics and the gap distance of the electric arc injection was obtained through the lightning adhesion process monitoring unit.

[0054] The first sample S1 was subjected to lightning strike tests at different arc injection gap distances D1 to D5 and even more gap distances. The specific test method was to gradually increase the discharge voltage until an arc discharge could occur.

[0055] 4) During the discharge process, the lightning strike attachment process monitoring unit 4 is used to record the entire process of the occurrence and development of lightning arcs on standing trees in the forest.

[0056] 5) Repeat steps 2) to 5) to conduct lightning strike adhesion tests on all standing tree samples; establish a correlation database between lightning adhesion on forest standing trees and multiple factors such as standing tree moisture content, lightning current parameters, and arc injection gap distance, and obtain an evaluation method for the distribution characteristics of lightning strike adhesion on forest standing trees.

[0057] 6) Statistical analysis was performed on all lightning strike test results to obtain the correlation between lightning-induced adhesion on standing trees and factors such as the moisture content of the standing tree sample and the distance of the arc injection gap, thus forming the distribution characteristics of lightning-induced adhesion on standing trees.

[0058] The sample selection and treatment method is as follows: select standing forest samples from typical forest areas and treat the samples, including humidity and moisture content, to simulate the actual environment of different plants under different seasons and climatic conditions. The height of the standing samples can range from 50mm to 100mm or even higher.

[0059] Statistical analysis of the lightning strike test results was conducted, including research on the characteristics and influencing factors of lightning strike attachment points on standing trees. This mainly included two aspects: First, adjusting the gap distance between the arc injection electrode and the end face of the sample forest standing tree, applying lightning pulse waves of different intensities, and obtaining the lightning attachment process and the attachment area of ​​lightning on the end face of the sample forest standing tree through the lightning attachment process monitoring unit; Second, analyzing the lightning attachment points of the forest standing trees, establishing a correlation database between lightning attachment on forest standing trees and multiple factors through experiments, and using a multi-factor regression method to obtain an evaluation method for the distribution characteristics of lightning attachment on forest standing trees.

[0060] During the lightning strike test, the rated discharge power supply of the lightning pulse generation unit should be no less than 300kV, and a single-stage direct discharge method using a controllable discharge switch operating in a high-pressure gas or vacuum environment should be adopted. This effectively avoids the defects of asynchronous or non-discharge, or discharge failure, caused by the multi-stage MARX discharge circuit commonly used in traditional high-voltage pulse power supplies. In order to obtain the lightning adhesion characteristics of the standing timber samples under different arc injection gaps, the pulse current / energy injected into the standing timber during lightning discharge should not be too large, and it is recommended to be between a few hundred A and a few kA, so as not to damage the standing timber and make it impossible to complete the test covering a distance of no less than 5 arc injection gaps.

[0061] The lightning strike attachment point analysis method uses statistical data analysis to analyze the distribution characteristics of attachment points by combining observations from lightning strike monitoring units with manual observations. This method ultimately obtains the correlation between lightning strike attachment on standing trees and factors such as the moisture content of the standing tree sample and the distance of the arc injection gap. This forms a lightning strike attachment point database that simulates the characteristics of forest lightning fires in different regions, laying the foundation for multi-physics modeling of forest combustibles by lightning, research on lightning fire mechanisms and prediction algorithms.

Claims

1. A test system for lightning strike attachment points on standing trees in forests, characterized in that: It includes a lightning pulse source (1), a sample forest standing tree (2), a lightning pulse source control and lightning pulse measurement and analysis unit (3), an arc injection clamping mechanism and adjustment unit, and a lightning strike attachment process monitoring unit (4). The lightning pulse source (1) includes a controllable high-voltage DC charging power supply (1-1) and a lightning pulse generating unit (1-2) for generating lightning pulse waves. The charging voltage of the controllable high-voltage DC charging power supply (1-1) to the lightning pulse generating unit (1-2) is monitored online by a charging voltage monitoring sensor (1-3), and the analog charging voltage is transmitted to the control unit (31) of the lightning pulse source control and lightning pulse measurement and analysis unit (3). The sample forest standing trees (2) are clamped by an electric arc injection clamping mechanism and an adjustment unit. The electric arc injection clamping mechanism and adjustment unit realize the electric arc injection of lightning into the sample forest standing trees (2) and realize the adjustment of the gap distance between the electric arc injection and the sample forest standing trees. The lightning pulse source control and lightning pulse measurement and analysis unit (3) consists of a control unit (31) and a lightning pulse measurement and analysis unit (32), and is used to realize the control of the lightning strike attachment point test and the measurement and analysis of lightning pulse parameters; The control unit (31) includes a charging voltage monitoring circuit (31-1), a programmable controller and its related control circuit (31-2). The charging voltage monitoring circuit (31-1) of the control unit (31) receives the signal transmitted from the charging voltage monitoring sensor (1-3), and after processing by the programmable controller and its related control circuit (31-2), it controls the discharge of the high voltage discharge switch G of the lightning pulse generating unit (1-2). The lightning pulse measurement and analysis unit (32) includes a pulse voltage sensor (32-1), a pulse current sensor (32-2), a digital oscilloscope (32-3), and an industrial control computer (32-4). The pulse voltage sensor (32-1), the pulse current sensor (32-2), and the array oscilloscope (32-3) work together to measure the lightning voltage between the lightning arc injection point of the standing tree and the low-voltage end of the standing tree, as well as the lightning current flowing through the standing tree. The industrial control computer (32-4) processes and analyzes the pulse voltage and pulse current signals measured by the oscilloscope to obtain the lightning voltage under parameters including the moisture content of the standing tree, ambient temperature and humidity, and arc injection gap distance. U Lightning current I The industrial control computer (32-4) and the programmable logic controller and its related control circuit (31-2) are combined to control the connection / disconnection, high voltage rise / fall and high voltage discharge switch G gap distance of the charging process of the forest standing tree attachment characteristic test, so as to realize the automatic control of the forest standing tree lightning strike attachment point test process. The lightning strike attachment process monitoring unit (4) includes a high-speed camera monitoring instrument (41-1) and a high-speed camera control computer (41-2), which are used to obtain the arc generation and development process of the lightning strike attachment process.

2. The forest standing tree lightning strike attachment point test system according to claim 1, characterized in that: The controllable high-voltage DC charging power supply (1-1) adopts a voltage multiplier charging method, consisting of an electronically controlled voltage regulator T1, a transformer T2, and a voltage multiplier capacitor C. B It consists of rectifier silicon stack D1, rectifier silicon stack D2, and current-limiting resistor Rc.

3. The forest standing tree lightning strike attachment point test system according to claim 1, characterized in that: The lightning pulse generating unit (1-2) consists of a main pulse energy storage capacitor. C 1. High-voltage discharge switch G, waveform forming resistor R1, waveform forming resistor R 2 and the formation of capacitance C The sample forest standing trees are connected to the output end of the lightning pulse generation unit (1-2) through an electric arc injection clamping mechanism and adjustment unit.

4. The forest standing tree lightning strike attachment point test system according to claim 3, characterized in that: The high-voltage discharge switch G includes a high-voltage electrode (a2) and a low-voltage electrode (a3) ​​enclosed in an insulating shell (a1). The high-voltage electrode extends from the top of the insulating shell to a terminal, and the low-voltage electrode extends from the top of the insulating shell to a terminal. A bellows telescopic mechanism is fitted outside the low-voltage electrode. The position of the low-voltage electrode (a3) ​​is adjusted by the bellows telescopic mechanism to adjust the anti-electric gap.

5. The forest standing tree lightning strike attachment point test system according to claim 4, characterized in that: The internal air pressure of the insulating shell is 2×10⁻⁶. 5 Pa -5×10 5 Pa, an insulating outer jacket (a5) with an umbrella-shaped structure is provided on the outside of the insulating outer shell (a1).

6. The forest standing tree lightning strike attachment point test system according to claim 1, characterized in that: The arc injection clamping mechanism and adjustment unit include a clamp and adjustment mechanism and an electrode adjustment mechanism; the clamp and adjustment mechanism includes a sample forest tree (2) fixing clamp mounted on a metal plate, with the bottom end face of the tree in close contact with the metal plate; the electrode adjustment mechanism includes a pair of metal electrodes and an electrode gap distance adjustment mechanism, the metal electrodes include high-voltage injection and return electrodes, the high-voltage end of the lightning pulse source is connected to the high-voltage injection electrode, and the end face of the high-voltage injection electrode is in a certain gap distance with the end face of the sample forest tree; the low-voltage end of the lightning pulse source is connected to the return electrode, and the return electrode is connected to the metal mounting plate; the electrode gap distance adjustment mechanism is a lifting mechanism set on one side, the high-voltage injection electrode is mounted on the lifting mechanism, and the height of the high-voltage injection electrode is adjusted by the lifting mechanism, thereby adjusting the gap distance between the high-voltage injection electrode and the end face of the sample forest tree.

7. The forest standing tree lightning strike attachment point test system according to claim 6, characterized in that: The high-pressure injection electrode is an electrode with a rounded end or a pointed tip. The distance between the high-pressure injection electrode and the end face of the forest standing tree (2) can be adjusted from 1 mm to 100 mm or even larger.

8. A method for testing and analyzing the distribution characteristics of lightning strike attachment points on standing trees in forests based on the test system described in claim 1, characterized in that... Includes the following steps: 1) Sample selection and treatment: Select forest standing tree samples from typical forest areas and treat the samples to prepare multiple standing tree samples with different moisture contents; 2) Electrically connect the arc injection clamping mechanism and adjustment unit to the lightning pulse generation unit, install the forest standing tree in the clamping mechanism, fix the position and gap distance between the high voltage injection electrode and the end face of the sample forest standing tree, apply lightning pulse waves of different intensities, and obtain the relationship between the lightning attachment process and the lightning pulse parameters through the lightning attachment process monitoring unit. 3) Adjust the position and gap distance between the high-voltage injection electrode and the end face of the forest standing tree sample, apply lightning pulse waves of different intensities, and obtain the correlation between lightning adhesion characteristics and arc injection gap distance through the lightning adhesion process monitoring unit. 4) Lightning strike tests were conducted on the first sample at different arc injection gap distances D1 to D5. The discharge voltage was gradually increased at each arc injection gap distance until arc discharge could occur. 5) Repeat steps 2) to 5) until all standing tree specimens have undergone lightning strike adhesion tests; establish a correlation database between forest standing tree lightning adhesion and multiple factors such as standing tree moisture content, lightning current parameters, and arc injection gap distance, and obtain an evaluation method for the distribution characteristics of forest standing tree lightning adhesion. 6) Statistical analysis was performed on all lightning strike test results to obtain the correlation between lightning-induced adhesion on standing trees and the moisture content of the standing tree sample and the arc injection gap distance factor, thus forming the distribution characteristics of lightning-induced adhesion on standing trees.

9. The method for testing and analyzing the distribution characteristics of lightning strike attachment points on standing trees in forests according to claim 8, characterized in that: Statistical analysis was conducted on the lightning strike test results, including a study on the characteristics and influencing factors of lightning strike attachment points on standing trees. This included adjusting the gap between the arc injection electrode and the end face of the sample forest standing tree, applying lightning pulse waves of different intensities, and obtaining the lightning attachment process and the attachment area of ​​lightning on the end face of the sample forest standing tree through a lightning attachment process monitoring unit. The analysis of the lightning attachment points on the forest standing trees was conducted, and a correlation database between lightning attachment on forest standing trees and multiple factors was established through experiments. A multi-factor regression method was used to obtain an evaluation method for the distribution characteristics of lightning attachment on forest standing trees.

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