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

Abstract

The invention discloses a forest stumpage 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 stumpage, 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. According to the lightning stroke attachment point analysis method, a data statistical method is applied, statistical analysis is carried out on attachment point distribution characteristics through observation results of a lightning stroke process monitoring unit and comprehensive manual observation, and finally correlation among factors such as the water content of stumpage lightning stroke attached stumpage samples, the arc injection gap distance and the like is obtained. A lightning stroke attachment point database simulating forest lightning stroke characteristics of different regional characteristics is formed, and a foundation is laid for multi-physics field modeling of forest combustible lightning stroke and research of a lightning stroke mechanism and a prediction algorithm.

Description

Technical Field

[0001] The invention belongs to forest lightning test technology, relates to a test method for forest lightning fire attachment characteristics and a lightning attachment law test technology, and particularly relates to a forest standing tree lightning attachment point test system and a lightning attachment point distribution characteristic test and analysis method. Background Art

[0002] With global warming and the increase in extreme weather, lightning activities are frequent and the frequency of lightning fires has increased significantly, which not only seriously damages forest resources and the ecological environment, but also poses great harm to people's lives, property and public safety, and poses a huge threat to the sustainable development of the national economy and ecological security. In the past 10 years, the proportion of lightning fires in major forest fires in my country has increased from 5% to more than 60%. The cause mechanism of lightning fires is complex, and it is difficult to monitor and detect, and difficult to extinguish and deal with. The monitoring, early warning and prevention and control of lightning fires have become a global problem.

[0003] Lightning is a multiple continuous time-series discharge process. In the process of multiple lightning strikes, the first lightning component plays a vital role, involving the attachment process of lightning strikes to forest vegetation, standing trees and other combustibles, which directly affects the lightning shunt characteristics of lightning current in vegetation, standing trees, humus layers and other combustibles. It is of great significance to the theoretical study of the smoldering or ignition mechanism of forest lightning strikes. Existing research on lightning fires is mainly based on the establishment of prediction models based on historical lightning fire data, and the probability and area of ​​lightning fire occurrence are predicted according to meteorological conditions and forest conditions. There are few research literature reports on the generation process of lightning fires based on physical action processes or action mechanisms. Therefore, this prediction model is difficult to guarantee the accuracy of lightning warning. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a forest standing tree lightning attachment point test system and a lightning attachment point distribution characteristic test and analysis method, so as to lay a foundation for the research of multi-physical field modeling of forest combustible lightning strikes, lightning fire mechanism and prediction algorithm.

[0005] The present invention is achieved through the following technical solutions:

[0006] A forest standing tree lightning attachment point test system, comprising 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 an adjustment unit, and a lightning attachment process monitoring unit;

[0007] The lightning pulse source includes a controllable high-voltage DC charging power supply and a lightning pulse generating unit, which are used to generate lightning pulse waves; the charging voltage of the lightning pulse generating unit of the controllable high-voltage DC charging power supply is monitored online by a charging voltage monitoring sensor, and the charging voltage analog quantity is transmitted to the control unit of the lightning pulse source control and the lightning pulse measurement and analysis unit;

[0008] The sample forest trees are clamped by the arc injection clamping mechanism and the adjustment unit, and the arc injection of lightning arcs to the sample forest trees is realized by the arc injection clamping mechanism and the adjustment unit, and the arc injection and the gap distance between the sample forest trees are adjusted.

[0009] The lightning pulse source control and lightning pulse measurement and analysis unit is composed of a control unit and a lightning pulse measurement and analysis unit, and is used to control the lightning attachment point test and measure and analyze lightning pulse parameters;

[0010] The lightning attachment process monitoring unit comprises a high-speed camera monitoring instrument and a high-speed camera control computer, which are used to obtain the arc occurrence and development process of the lightning attachment process.

[0011] Furthermore, the controllable high-voltage DC charging power supply adopts a voltage doubling charging mode, which is composed of an electronically controlled voltage regulator T1, a transformer T2, and a voltage doubling capacitor C B , rectifier silicon stack D1, rectifier silicon stack D2 and current limiting resistor Rc.

[0012] Furthermore, the lightning pulse generating unit is composed of a main pulse energy storage capacitor C1, a high-voltage discharge switch G, a waveform forming resistor R1, a waveform forming resistor R2 and a forming capacitor C2. The sample forest standing trees are injected into the clamping mechanism and the adjustment unit through the arc and connected to the output end of the lightning pulse generating unit.

[0013] Furthermore, the high-voltage discharge switch G includes a high-voltage electrode and a low-voltage electrode enclosed in an insulating shell, the high-voltage electrode extends a terminal from the top of the insulating shell, the low-voltage electrode extends a terminal from the top of the insulating shell, and a bellows expansion and contraction mechanism is provided on the outside of the low-voltage electrode. The position of the low-voltage electrode is adjusted by the bellows expansion and contraction mechanism to achieve adjustment of the anti-electric gap.

[0014] Furthermore, the air pressure in the insulating housing is 2×10 5 Pa-5×10 5 Pa, an insulating jacket with an umbrella skirt structure is arranged outside the insulating shell.

[0015] 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 by the charging voltage monitoring sensor, and after being processed by the programmable controller and related control circuits, performs discharge control on the high-voltage discharge switch G of the lightning pulse generating unit.

[0016] 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, the pulse current sensor and the array oscilloscope are combined to measure the lightning voltage between the standing tree lightning arc injection point and the standing tree low-voltage end and the lightning current flowing through the standing tree; the industrial control computer processes and analyzes the pulse voltage and pulse current signals measured by the oscilloscope, thereby obtaining the lightning voltage U and lightning current I under parameters including standing tree parameters, environmental temperature and humidity, and arc injection gap distance; the industrial control computer is combined with a programmable controller and its related control circuits to control the connection / disconnection, high voltage increase / decrease and gap distance adjustment of the charging process of the forest standing tree attachment characteristic test, thereby realizing automatic control of the forest standing tree lightning attachment point test process.

[0017] Furthermore, the arc injection clamping mechanism and adjustment unit include a clamp and adjustment mechanism and an electrode adjustment mechanism; the clamp and adjustment mechanism include a sample forest tree fixing clamp installed on a metal plate, and the bottom end surface of the tree is 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 electrode includes 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 surface of the high-voltage injection electrode has a certain gap distance from the end surface 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 arranged on one side, the high-voltage injection electrode is installed on the lifting mechanism, the height of the high-voltage injection electrode is adjusted by the lifting mechanism, and then the gap distance between the high-voltage injection electrode and the end surface of the sample forest tree is adjusted.

[0018] Furthermore, the high-voltage injection electrode is an electrode with an arc end or a pointed end, and the distance between the high-voltage injection electrode and the end face of the sample forest tree can be adjusted in the range of 1 mm to 100 mm or even larger.

[0019] A method for testing and analyzing the distribution characteristics of lightning strike attachment points of standing trees in a forest, comprising the following steps:

[0020] 1) Sample selection and processing: Select forest standing tree samples from typical forest areas, process the samples, and prepare multiple standing tree samples with different moisture contents;

[0021] 2) The arc injection clamping mechanism and the adjustment unit are electrically connected to the lightning pulse generating unit, the forest tree is installed in the clamping mechanism, the position and gap distance between the high-voltage injection electrode and the end face of the sample forest tree are fixed, lightning pulse waves of different intensities are applied, and the relationship between the lightning attachment process and the lightning pulse parameters is obtained through the lightning attachment process monitoring unit;

[0022] 3) Adjust the position and gap distance between the high-voltage injection electrode and the end face of the sample forest tree, apply lightning pulse waves of different intensities, and obtain the correlation between lightning attachment characteristics and arc injection gap distance through the lightning attachment process monitoring unit;

[0023] 4) Conduct lightning strike tests on the first sample at different arc injection gap distances D1 to D5, and gradually increase the discharge voltage at each arc injection gap distance until arc discharge can occur;

[0024] 5) Repeat steps 2) to 5) until the lightning attachment test of all standing tree samples is completed; establish a correlation database between the lightning attachment of forest standing trees and the moisture content of standing trees, lightning current parameters, and arc injection gap distance, and obtain an evaluation method for the distribution characteristics of lightning attachment of forest standing trees;

[0025] 6) Statistical analysis was performed on all lightning strike test results to obtain the correlation between lightning strike attachment to standing trees and the moisture content of standing tree specimens and arc injection gap distance factors, thus forming the distribution characteristics of lightning strike attachment to standing trees.

[0026] Furthermore, the results of the lightning strike tests were statistically analyzed, including a study of the characteristics and influencing factors of the attachment points of lightning strikes on standing trees, including adjusting the gap distance between the arc injection electrode and the end face of the sample forest tree, applying lightning pulse waves of different intensities, and obtaining the lightning attachment process and the lightning attachment area on the end face of the sample forest tree through a lightning attachment process monitoring unit; analyzing the lightning attachment points of the forest trees, establishing a correlation database between forest tree lightning attachment and other factors through experiments, and using a multi-factor regression method to obtain an evaluation method for the distribution characteristics of forest tree lightning attachment.

[0027] The present invention establishes a forest standing tree lightning attachment point test system, proposes a standing tree lightning attachment point test method, performs statistical analysis on the attachment point distribution characteristics through the observation results of the lightning process monitoring unit and comprehensive manual observation, and finally obtains the correlation between the standing tree lightning attachment and the standing tree sample moisture content, arc injection gap distance and other factors, forms a lightning attachment point database that simulates the forest lightning fire characteristics of different regional characteristics, obtains the correlation law between the lightning standing tree attachment characteristics and the lightning electrical parameters, action conditions and standing tree natural and ecological environment characteristics, determines the forest standing tree lightning attachment distribution law, provides the initial distribution state of arc injection for the multi-physics field modeling calculation of the lightning standing tree ignition fire mechanism, and lays a foundation for the multi-physics field modeling of forest combustible lightning, the research of lightning fire mechanism and prediction algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural block diagram of the forest standing tree lightning strike attachment point test system of the present invention;

[0029] Figure 2 This is a circuit principle block diagram of the forest standing tree lightning strike attachment point test system of the present invention;

[0030] Figure 3 It is a structural block diagram of the high-voltage discharge switch G of the present invention;

[0031] Figure 4 It is a structural diagram of the arc injection clamping mechanism and the adjustment unit of the present invention;

[0032] Among them, (a) is a top view, and (b) is a stereogram;

[0033] Figure 5 This is a flow chart of the test and analysis method for the distribution characteristics of lightning attachment points on standing trees in forests. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0035] See also Figure 1 and Figure 2 As shown, the forest tree lightning attachment point test system of the present invention is composed of a lightning pulse source 1, a sample forest 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.

[0036] The lightning pulse source 1 is mainly composed of a controllable high-voltage DC charging power supply 1-1 and a lightning pulse generating unit 1-2. In actual tests, 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 the charging voltage monitoring sensor 1-3, and the charging voltage analog quantity 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 a lightning pulse wave.

[0037] The function of the lightning pulse source control and lightning pulse measurement and analysis unit 3 is to realize the control of the lightning attachment point test and the measurement and analysis of the lightning pulse parameters, and is mainly composed of a control unit 31 and a lightning pulse measurement and analysis unit 32. Among them, the control unit 31 is mainly composed of 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 by the charging voltage monitoring sensor 1-3, and after being measured and processed by the programmable controller and its related control circuit 31-2, it can output a control signal to the programmable controller and its related control circuit 31-2, thereby controlling the discharge of the high-voltage discharge switch G of the lightning pulse generating unit 1-2. In addition, the programmable controller and its related control circuit 31-2 are also combined with the industrial control computer 32-4 of the lightning pulse measurement and analysis unit 32 to control the connection / disconnection, high voltage increase / decrease, and adjustment of the gap distance of the high-voltage discharge switch G of the charging process of the forest standing tree attachment feature test, so as to realize the automatic control of the forest standing tree lightning attachment point test process.

[0038] The function of the lightning pulse measurement and analysis unit 32 is to realize the control of the lightning attachment point test and the measurement and analysis of the lightning pulse parameters, and to realize the process control of the forest standing tree attachment characteristic test and the measurement and analysis of the lightning parameters. The lightning pulse measurement and analysis unit 32 is mainly composed 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, the pulse current sensor 32-2 and the array oscilloscope 32-3 are combined to measure the lightning voltage between the standing tree lightning arc injection point and the standing tree low-voltage end and 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, thereby obtaining the lightning voltage U and lightning current I under parameters including standing tree parameters, environmental temperature and humidity, and arc injection gap distance.

[0039] The lightning attachment process monitoring unit 4 observes the arc occurrence and development process of the lightning attachment process, and is mainly composed 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 of the standing tree, and its camera process is controlled by the high-speed camera control computer 41-2. The lightning attachment process of the lightning-struck standing tree is obtained through the lightning attachment process monitoring unit 4.

[0040] See also Figure 2 , which is the principle circuit of the lightning pulse source 1 for the lightning attachment characteristic test of forest standing trees of the present invention, mainly contains the circuit principle of the controllable high-voltage DC charging power supply 1-1 and the lightning pulse generating unit 1-2. In view of the high voltage environment with extremely high amplitude when the actual lightning strike occurs, the working voltage of the lightning pulse power supply in this application cannot be too low, at least not less than 300kV. For this reason, the controllable high-voltage DC charging power supply 1-1 adopts a voltage doubling charging method to avoid the occurrence of corona discharge during the experiment, which affects the reliability and stability of the lightning pulse source.

[0041] The controllable high-voltage DC charging power supply 1-1 is mainly composed of an electronically controlled voltage regulator T1, a transformer T2, and a voltage-doubling capacitor C B , rectifier silicon stacks D1 and D2 and current limiting resistor Rc.

[0042] Aiming at the defect of poor discharge synchronization of multi-stage discharge switches in the traditional high-voltage discharge MARX generation circuit, the present invention increases the stability of lightning pulse source discharge, and adopts a method of directly discharging the energy storage capacitor through a discharge switch. The lightning pulse generation unit 1-2 is mainly composed of a main pulse energy storage capacitor C1, a high-voltage discharge switch G, waveform forming resistors R1 and R2, and a forming capacitor C2, which are electrically connected in series and parallel connection, and the sample forest standing trees and their connection fixtures are connected in parallel to the output end of the lightning pulse generation unit 1-2.

[0043] See also Figure 3 , is a structural block diagram of a 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 in an insulating housing a1. A connection terminal of the high-voltage electrode a2 extends from the top of the insulating housing a1, and a connection terminal of the low-voltage electrode a3 extends from the bottom of the insulating housing a1. A bellows expansion and contraction mechanism is sleeved on the outside of the low-voltage electrode a3. The bellows expansion and contraction mechanism includes a bellows a4 and a low-voltage electrode driving mechanism. The low-voltage electrode is sealed with the inside of the insulating housing a1 through the bellows. The low-voltage electrode driving mechanism can adopt a structure such as a telescopic motor or a cylinder to drive the low-voltage electrode to move in the insulating housing a1.

[0044] The high-voltage discharge switch G is a high-voltage, high-current controllable discharge switch that works 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. According to the system rated voltage of 300kV, the DC withstand voltage of the discharge switch is 400kV. For the discharge switch working in a high-pressure environment, its internal insulation can be 2-5×10 5 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.

[0045] The high voltage, high current discharge switch can also operate at 10 -1 In a vacuum environment of 1.5 Pa, the internal insulation of the discharge switch can also be solved. In order to meet the requirements of reliable operation of lightning pulse generating units of different voltage levels, the low-voltage electrode a3 of the high-voltage discharge switch in a closed environment is provided with a bellows telescopic mechanism with adjustable discharge gap distance.

[0046] In order to improve the reliability and credibility of the lightning attachment characteristics data of forest standing trees under repeated lightning discharges, the expected pulse discharge current of the lightning pulse discharge power supply when a breakdown discharge occurs in the standing trees should not be too large, and its maximum pulse current peak is limited to the order of hundreds of amperes to several kiloamperes.

[0047] See also Figure 4 As shown, the arc injection clamping mechanism and the adjustment unit are used to complete the clamping of the sample forest trees, realize the arc injection of the lightning arc into the sample forest trees, and realize the adjustment of the gap distance between the arc injection and the sample forest trees. It is mainly composed of the arc injection electrode mechanism and the arc injection electrode gap distance adjustment mechanism. Through the adjustment of the gap distance, it is possible to establish a correlation between the arc injection gap distance and the distribution of lightning attachment points, thereby laying the foundation for predicting the lightning attachment point database for forest lightning fire characteristics with different regional characteristics.

[0048] The arc injection clamping mechanism and adjustment unit mainly consists of a clamp and adjustment mechanism and an electrode adjustment mechanism, and its function is to fix the sample forest tree 2. The clamp and adjustment mechanism is a quadrilateral structure clamp b2 installed on a metal plate b1 with an adjustable locking position. The quadrilateral structure clamp b2 consists of four baffles connected by bolts. By adjusting the installation position of each baffle, the clamping of trees with different diameters can be achieved, and the bottom end surface of the 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, and its function is to connect the standing wood sample to the lightning pulse source circuit, wherein the high-voltage end of the lightning pulse source is connected to the high-voltage injection electrode of the arc injection clamping mechanism, and the high-voltage injection electrode is an electrode with an arc end or a tip, and there is a certain gap between the end face of the high-voltage injection electrode and the end face of the standing wood in the sample forest; the electrode gap distance adjustment mechanism is a lifting mechanism set on one side, and the high-voltage injection electrode is installed on the lifting mechanism. The height of the high-voltage injection electrode is adjusted by the lifting mechanism, and then the gap distance between the high-voltage injection electrode and the end face of the standing wood in the sample forest is adjusted. The lifting mechanism can be a hydraulic lifting mechanism, a motor-driven screw lifting mechanism, or a pneumatic lifting mechanism driven by a cylinder.

[0049] 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, and in order to ensure the uniformity of the diversion of the lightning strike current of the standing 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.

[0050] The distance between the lightning arc injection electrode and the end faces of the sample forest trees 2 can be adjusted automatically or manually, and the adjustment range can be 1mm-100mm or even larger.

[0051] See also Figure 5 , the distribution characteristics test and analysis method of lightning attachment points of forest standing trees, the specific test and analysis process is as follows:

[0052] 1) Sample selection and processing: Select forest standing tree samples with typical forest areas and process the samples, including humidity and moisture content, to simulate the actual environment of different plants in different seasons and climatic conditions. Prepare standing tree samples with different moisture contents, at least 5 samples with different moisture contents (recorded as S1 to S5), and the samples can be selected in typical forest areas with different climatic and environmental characteristics (such as Daxing'anling, Liangzhou, etc.).

[0053] 2) The arc injection clamping mechanism and the adjustment unit are electrically connected to the lightning pulse generating unit of the lightning pulse source, the forest standing tree is installed in the clamping mechanism, and the arc injection clamping mechanism and the adjustment unit are electrically connected to the lightning pulse generating unit of the lightning pulse source; the position and gap distance between the arc injection and the end face of the sample forest standing tree are fixed, and lightning pulse waves of different intensities are applied. Through the lightning attachment process monitoring unit, the relationship between the lightning attachment process and the lightning pulse parameters is obtained. At least 5 arc injection gap distances are selected, and the arc injection distance range covers 10mm-100mm or even larger.

[0054] 3) The position and gap distance between the arc injection and the end face of the sample forest tree are adjusted, and lightning pulse waves of different intensities are applied. The correlation between the lightning attachment characteristics and the arc injection gap distance is obtained through the lightning attachment process monitoring unit.

[0055] The first sample S1 is subjected to a lightning strike test at different arc injection gap distances D1 to D5 or even more gap distances. The specific test method is to gradually increase the discharge voltage until arc discharge can occur.

[0056] 4) During the discharge process, the lightning attachment process monitoring unit 4 is used to record the entire process of the occurrence and development of the lightning arc of the forest standing trees.

[0057] 5) Repeat steps 2) to 5) to conduct lightning attachment tests on all standing tree samples; establish a correlation database between lightning attachment of 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 attachment of forest standing trees;

[0058] 6) Statistical analysis was performed on all lightning strike test results to obtain the correlation between lightning strike attachment to standing trees and factors such as moisture content of standing tree specimens and arc injection gap distance, thus forming the distribution characteristics of lightning strike attachment to standing trees.

[0059] The sample selection and processing method is: select forest standing tree samples with typical forest areas and process the samples, including humidity, moisture content, etc., to simulate the actual environment of different plants in different seasons and different climatic conditions. The height of the sample standing tree can range from 50mm-100mm or even higher.

[0060] The results of lightning strike tests were statistically analyzed, including the study of the characteristics and influencing factors of the attachment points of lightning strikes on standing trees, which mainly included two aspects: one was to adjust the gap distance between the arc injection electrode and the end face of the sample forest standing tree, apply lightning pulse waves of different intensities, and obtain the lightning attachment process and the lightning attachment area on the end face of the sample forest standing tree through the lightning attachment process monitoring unit; the second was to analyze the lightning attachment points of the forest standing trees, establish a correlation database between the forest standing tree lightning attachment and other factors through experiments, and use the multi-factor regression method to obtain the evaluation method of the distribution characteristics of the forest standing tree lightning attachment.

[0061] During the lightning test, the rated discharge power of the lightning pulse generating unit is not less than 300kV, and the first-level direct discharge method of the controllable discharge switch working in high-pressure gas or vacuum environment is adopted, which effectively avoids the defects of the multi-level discharge switch discharging asynchronously or not discharging and discharging failure caused by the multi-level MARX discharge circuit commonly used in traditional high-voltage pulse power supplies. In order to obtain the lightning attachment characteristics of the standing wood specimens under different arc injection gaps, it is required that the pulse current / energy injected into the standing wood during lightning discharge should not be too large, and it is recommended to be between 100A and several kA, so as not to cause damage to the standing wood and fail to complete the test covering a distance of not less than 5 arc injection gaps.

[0062] The lightning attachment point analysis method uses data statistical methods, through the observation results of the lightning process monitoring unit, and combined with manual observation to conduct statistical analysis on the distribution characteristics of the attachment points, and finally obtains the correlation between standing tree lightning attachment and standing tree sample moisture content, arc injection gap distance and other factors, forming a lightning attachment point database that simulates the characteristics of forest lightning fires in different regional characteristics, laying the foundation for multi-physical field modeling of forest combustible lightning strikes, lightning fire mechanisms and prediction algorithms.

Claims

1. A forest standing tree lightning attachment point test system, characterized by: It comprises a lightning pulse source (1), a sample forest tree (2), a lightning pulse source control and lightning pulse measurement and analysis unit (3), an arc injection clamping mechanism and an adjustment unit, and a lightning strike attachment process monitoring unit (4); The lightning pulse source (1) comprises a controllable high-voltage direct current charging power supply (1-1) and a lightning pulse generating unit (1-2), and is used to generate a lightning pulse wave; the controllable high-voltage direct current charging power supply (1-1) monitors the charging voltage of the lightning pulse generating unit (1-2) online via a charging voltage monitoring sensor (1-3), and transmits the charging voltage analog quantity to a control unit (31) of a lightning pulse source control and a lightning pulse measuring and analyzing unit (3); The sample forest tree (2) is clamped by an arc injection clamping mechanism and an adjustment unit, and arc injection of lightning arcs into the sample forest tree (2) is achieved by the arc injection clamping mechanism and the adjustment unit, and adjustment of the gap distance between the arc injection and the sample forest tree is achieved. The lightning pulse source control and lightning pulse measurement and analysis unit (3) is composed of a control unit (31) and a lightning pulse measurement and analysis unit (32), and is used to control the lightning attachment point test and measure and analyze lightning pulse parameters; The lightning strike attachment process monitoring unit (4) comprises 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 doubling charging method, which is composed of an electronically controlled voltage regulator T1, a transformer T2, and a voltage doubling capacitor C B , rectifier silicon stack D1, rectifier silicon stack D2 and current limiting resistor Rc.

3. The forest standing tree lightning attachment point test system according to claim 1, characterized in that: The lightning pulse generating unit (1-2) is composed of a main pulse energy storage capacitor C1, a high-voltage discharge switch G, a waveform forming resistor R1, a waveform forming resistor R2 and a forming capacitor C2. The sample forest standing trees are injected into the clamping mechanism and the adjustment unit through the arc and connected to the output end of the lightning pulse generating unit (1-2).

4. The forest standing tree lightning strike attachment point test system according to claim 1, characterized in that: The high-voltage discharge switch G comprises a high-voltage electrode (a2) and a low-voltage electrode (a3) ​​which are enclosed in an insulating shell (a1); a connection terminal of the high-voltage electrode extends from the top of the insulating shell; a connection terminal of the low-voltage electrode extends from the top of the insulating shell; a bellows expansion and contraction mechanism is provided on the outside of the low-voltage electrode; the position of the low-voltage electrode (a3) ​​is adjusted by the bellows expansion and contraction mechanism to achieve adjustment of the anti-electric gap.

5. The forest standing tree lightning attachment point test system according to claim 1, characterized in that: The air pressure in the insulating shell is 2×10 5 Pa-5×10 5 Pa, an insulating jacket (a5) with an umbrella skirt structure is arranged outside the insulating shell (a1).

6. The forest standing tree lightning attachment point test system according to claim 1, characterized in that: The control unit (31) comprises 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 a signal transmitted by a charging voltage monitoring sensor (1-3), and after being processed by the programmable controller and its related control circuit (31-2), performs discharge control on a high-voltage discharge switch G of a lightning pulse generating unit (1-2); The lightning pulse measurement and analysis unit (32) comprises 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) are combined to measure the lightning voltage between the standing tree lightning arc injection point and the standing tree low-voltage end and 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, thereby obtaining the lightning voltage U and lightning current I under parameters including standing tree parameters, environmental temperature and humidity, and arc injection gap distance; the industrial control computer (32-4) is combined with a programmable controller and its related control circuit (31-2) to control the connection / disconnection, high voltage increase / decrease and gap distance adjustment of the charging process of the forest standing tree attachment characteristic test, thereby realizing automatic control of the forest standing tree lightning attachment point test process.

7. 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 comprises a clamp and adjustment mechanism and an electrode adjustment mechanism; the clamp and adjustment mechanism comprises a sample forest tree (2) fixing clamp installed on a metal plate, the bottom end face of the tree is in close contact with the metal plate; the electrode adjustment mechanism comprises a pair of metal electrodes and an electrode gap distance adjustment mechanism, the metal electrodes comprise 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 has 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 arranged on one side, the high-voltage injection electrode is installed on the lifting mechanism, the height of the high-voltage injection electrode is adjusted by the lifting mechanism, and then the gap distance between the high-voltage injection electrode and the end face of the sample forest tree is adjusted.

8. The forest standing tree lightning attachment point test system according to claim 1, characterized in that: The high-voltage injection electrode is an electrode with an arc end or a pointed end, and the distance between the high-voltage injection electrode and the end face of the sample forest tree (2) can be adjusted in the range of 1mm-100mm or even larger.

9. A method for testing and analyzing the distribution characteristics of lightning strike attachment points of forest trees based on the test system of claim 1, characterized in that The steps include: 1) Sample selection and processing: Select forest standing tree samples from typical forest areas, process the samples, and prepare multiple standing tree samples with different moisture contents; 2) The arc injection clamping mechanism and the adjustment unit are electrically connected to the lightning pulse generating unit, the forest tree is installed in the clamping mechanism, the position and gap distance between the high-voltage injection electrode and the end face of the sample forest tree are fixed, lightning pulse waves of different intensities are applied, and the relationship between the lightning attachment process and the lightning pulse parameters is obtained 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 sample forest tree, apply lightning pulse waves of different intensities, and obtain the correlation between lightning attachment characteristics and arc injection gap distance through the lightning attachment process monitoring unit; 4) Conduct lightning strike tests on the first sample at different arc injection gap distances D1 to D5, and gradually increase the discharge voltage at each arc injection gap distance until arc discharge can occur; 5) Repeat steps 2) to 5) until the lightning attachment test of all standing tree samples is completed; establish a correlation database between the lightning attachment of forest standing trees and the moisture content of standing trees, lightning current parameters, and arc injection gap distance, and obtain an evaluation method for the distribution characteristics of lightning attachment of forest standing trees; 6) Statistical analysis was performed on all lightning strike test results to obtain the correlation between lightning strike attachment to standing trees and the moisture content of standing tree specimens and arc injection gap distance factors, thus forming the distribution characteristics of lightning strike attachment to standing trees.

10. The method for testing and analyzing the distribution characteristics of lightning strike attachment points of standing trees in a forest according to claim 9, characterized in that: The results of lightning strike tests were statistically analyzed, including the study of the characteristics and influencing factors of the attachment points of lightning strikes on standing trees, including 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 lightning attachment area on the end face of the sample forest standing tree through the lightning attachment process monitoring unit; analyzing the lightning attachment points of the forest standing trees, establishing a correlation database between the forest standing tree lightning attachment and other factors through experiments, and using the multi-factor regression method to obtain the evaluation method of the distribution characteristics of the forest standing tree lightning attachment.

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