Method and system for obtaining safe distance when fighting photovoltaic fire with water gun

Abstract

The application discloses a method and system for acquiring a safe distance when a water gun is used to extinguish a photovoltaic fire, and belongs to the technical field of new energy sources. L ; S2, real-time acquisition of a direct current voltage U P , a human body resistance R S , a safe voltage U S , and reasoning of a minimum length L S of a water column sprayed by the water gun under the safe voltage condition; S3, reasoning of a minimum safe distance L of live extinguishing according to the minimum length L S of the water column sprayed by the water gun under the safe voltage condition; and S4, the safe distance L' is not less than the minimum safe distance L. The application calculates and determines the live extinguishing safe distance according to the water gun flow intensity, the spraying angle, the photovoltaic component voltage and other factors, and effectively reduces the electric shock risk in the live extinguishing process using the water gun.

Description

Technical Field

[0001] This invention belongs to the field of new energy technology, and in particular relates to a method and system for obtaining a safe distance when using a water gun to extinguish a photovoltaic fire. Background Technology

[0002] In recent years, with the rapid development and widespread adoption of the photovoltaic industry, installed capacity has increased year by year, leading to a rise in fire hazards. Currently, research specifically on live-line firefighting techniques for photovoltaic power generation systems is relatively limited. This is because when photovoltaic modules receive sunlight during the day, each string generates hundreds of volts of DC voltage, and the power cannot be immediately cut off. Waiting to cut off the power before firefighting would delay the process, allowing the fire to spread and expand the burning area. Therefore, it is essential to conduct live-line firefighting while ensuring the safety of firefighters. Although water has some conductivity and can affect the insulation of electrical equipment, making it unsuitable for live-line photovoltaic firefighting, its high specific heat, excellent cooling effect, and high fire extinguishing efficiency (each kilogram of water evaporating at standard atmospheric pressure absorbs 2260.5 kJ of heat) make it a commonly used and inexpensive fire extinguishing agent, widely applied in live-line firefighting. For scenarios requiring firefighting and rescue, international research and regulations regarding safe firefighting distances have been developed. The NFPA Fire Protection Manual recommends using mist nozzles when extinguishing live photovoltaic equipment. If environmental conditions do not permit mist nozzles, solid nozzles can be used. The manual also specifies safe distances between solid nozzles and live equipment, but these safe distances are only based on protection against AC high voltage. IEEE 979, "Fire Protection Guidelines for Substations," specifies a minimum safe distance of 3 meters for firefighting under conditions of nozzle diameter (29-38 mm), nozzle pressure (0.5-0.7 MPa), and flow rate (750-950 L / min). H. Baatz, C. Buffet, M. J. Dogherty, and others have studied the risk of electric shock for firefighters under different nozzle pressures, diameters, and distances during firefighting operations.

[0003] The above research results only provide the distance for live-line firefighting in some scenarios, and fail to provide a calculation method for the safe distance for live-line firefighting that can be universally applied to multiple scenarios. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method and system for early fire detection and warning based on the power generation characteristics of photovoltaic modules. The safe distance for extinguishing energized fires is calculated and determined based on multiple factors such as water jet flow rate, spray angle, and photovoltaic module voltage, effectively reducing the risk of electric shock during energized firefighting with water jets.

[0005] The specific technical solution adopted in this invention is as follows:

[0006] The primary objective of this patent is to provide a method for determining the safe distance when using a water gun to extinguish a photovoltaic fire, including:

[0007] S1. Obtain the water gun volumetric flow rate Q in real time, and infer the resistance value R per unit distance of the water jet sprayed from the water gun based on the water gun volumetric flow rate Q. L When Q is in the range of 5 to 12m 3 When / h, the calculation formula is:

[0008] R L =m1+m2Q+m3Q 2 (1)

[0009] Where m1, m2, and m3 are experimental fitting constants;

[0010] S2. Real-time acquisition of DC voltage U at the location of the photovoltaic fire. P Human body resistance R S Safety voltage U S And according to the DC voltage U P Human body resistance R S Safety voltage U S Reasoning for the minimum length L of the water jet ejected from the water gun under safe voltage conditions. S The calculation formula is:

[0011]

[0012] S3. Based on the minimum length L of the water jet ejected by the water gun under safe voltage conditions. S The minimum safe distance L for extinguishing live electrical fires is deduced, and the calculation formula is as follows:

[0013]

[0014] b = tanθ

[0015] Where: θ is the angle between the water gun and the horizontal plane, and the unit is rad;

[0016] S4. Obtain the safe distance L' when using a water gun to extinguish a photovoltaic fire, wherein the safe distance L' is not less than the minimum safe distance L.

[0017] Preferably, m1 = 7787.97, m2 = -850.33, and m3 = 25.53.

[0018] A second objective of this invention is to provide a system for obtaining a safe distance when using a water gun to extinguish a photovoltaic fire, comprising:

[0019] The first parameter acquisition module acquires the water gun's volumetric flow rate Q in real time and obtains the resistance value R per unit distance of the water jet from the water gun based on the water gun's volumetric flow rate Q.L When Q is in the range of 5 to 12m 3 When / h, the calculation formula is:

[0020] R L =m1+m2Q+m3Q 2 (1)

[0021] Where m1, m2, and m3 are experimental fitting constants;

[0022] Second parameter acquisition module: Real-time acquisition of DC voltage U at the photovoltaic fire site. P Human body resistance R S Safety voltage U S And according to the DC voltage U P Human body resistance R S Safety voltage U S Obtain the minimum length L of the water jet ejected by the water gun under safe voltage conditions. S The calculation formula is:

[0023]

[0024] The third parameter acquisition module: During the water gun spraying process, the farthest distance is achieved by spraying in a parabolic manner. Therefore, based on the parabolic equation and the minimum length L of the water jet sprayed by the water gun under safe voltage conditions, S The minimum safe distance L for extinguishing live electrical fires is calculated using the following formula:

[0025]

[0026] b = tanθ

[0027] Where: θ is the angle between the water gun and the horizontal plane, and the unit is rad;

[0028] Result output module: Obtain the safe distance L' when using a water gun to extinguish a photovoltaic fire, wherein the safe distance L' is not less than the minimum safe distance L.

[0029] Preferably, m1 = 7787.97, m2 = -850.33, and m3 = 25.53.

[0030] A third objective of this invention is to provide a water gun equipped with the aforementioned system for determining a safe distance when using the water gun to extinguish a photovoltaic fire.

[0031] Preferably, the first parameter acquisition module includes a flow sensor installed on the water gun and a first calculation module that executes formula (1).

[0032] Preferably, the second parameter acquisition module includes a module for acquiring DC voltage U.P The voltage sensor and the second calculation module that executes formula (2).

[0033] Preferably, the third parameter acquisition module includes an angle measurement sensor installed on the water gun and a third calculation module that executes formula (3).

[0034] The fourth objective of this patent is to provide a computer program for obtaining the safe distance when using a water gun to extinguish a photovoltaic fire.

[0035] The fifth objective of this patent is to provide an information data processing terminal that implements the above-mentioned method for obtaining a safe distance when using a water gun to extinguish a photovoltaic fire.

[0036] The sixth objective of this patent is to provide a computer-readable storage medium, including instructions that, when executed on a computer, cause the computer to perform the aforementioned method for obtaining a safe distance when using a water gun to extinguish a photovoltaic fire.

[0037] The advantages and positive effects of this invention are as follows:

[0038] By adopting the above technical solution, the present invention has the following technical effects:

[0039] The present invention uses formula (1) to deduce the resistance of the water gun during the extinguishing process under different flow conditions, and then calculates the energization status at the location of the water gun. Based on different voltage conditions, it can guide firefighters to take different protective measures against electric shock.

[0040] This invention uses formulas (2) and (3) to deduce the safe distance for extinguishing live fires for photovoltaic components of different voltage levels and corresponding flow rates. This can guide firefighters to spray water cannons to extinguish photovoltaic fires from a safe location, effectively reducing the risk of electric shock during live fire extinguishing. Attached Figure Description

[0041] Figure 1 A flowchart of a preferred embodiment of the present invention;

[0042] Figure 2 This is a system block diagram in a preferred embodiment of the present invention;

[0043] Figure 3 This is a schematic diagram of a photovoltaic module live-line firefighting test platform in a preferred embodiment of the present invention;

[0044] Figure 4 This is a schematic diagram of the parabola of a horizontally ejected water column. Detailed Implementation

[0045] To further understand the invention's content, features, and effects, the following embodiments are provided, and detailed descriptions are given in conjunction with the accompanying drawings.

[0046] The structure of the present invention will now be described in detail with reference to the accompanying drawings.

[0047] Please see Figure 1 A method for determining a safe distance when using a water cannon to extinguish a photovoltaic fire, comprising:

[0048] S1. Obtain the water gun volumetric flow rate Q in real time, and infer the resistance value R per unit distance of the water jet sprayed from the water gun based on the water gun volumetric flow rate Q. L When Q is in the range of 5 to 12m 3 When / h, the calculation formula is:

[0049] R L =m1+m2Q+m3Q 2 (1)

[0050] Where: R L The resistance of the water jet per unit distance from the water gun is Ω / m; Q is the volumetric flow rate of the water gun, in m³ / s. 3 / h; m1, m2, and m3 are experimental fitting constants. Experimental tests showed that the resistance per unit distance of the water jet from the water gun decreases with increasing flow rate. Therefore, m1, m2, and m3 were obtained through experimental fitting. In this embodiment, m1 = 7787.97, m2 = -850.33, and m3 = 25.53. These values ​​were obtained through fitting calculations in multiple experiments.

[0051] S2. Real-time acquisition of DC voltage U at the location of the photovoltaic fire. P Human body resistance R S Safety voltage U S Parameters, and based on the DC voltage U P Human body resistance R S Safety voltage U S Reasoning for the minimum length L of the water jet ejected from the water gun under safe voltage conditions. S The calculation formula is:

[0052]

[0053] Where: L S The minimum length of the water jet ejected from the water gun under safe voltage conditions, in meters (m); U P The DC voltage at the point of origin of the fire in the photovoltaic power generation system, in V; U S The safe voltage for the human body, unit: V, usually taken as 36V; R S The resistance of the human body, measured in Ω, is typically taken as 2000Ω.

[0054] S3. Based on the experimental results, the following water gun trajectory was derived, according to the minimum length L of the water jet under safe voltage conditions. S The minimum safe distance L for extinguishing live electrical fires is deduced, and the calculation formula is as follows:

[0055]

[0056] b = tanθ

[0057] Where: θ is the angle between the water gun and the horizontal plane, in rad; L is the minimum safe distance for extinguishing electric shocks, in m; the unit is rad.

[0058] S4. Obtain the safe distance L' when using a water gun to extinguish a photovoltaic fire, wherein the safe distance L' is not less than the minimum safe distance L.

[0059] Please see Figure 4 The derivation process of the above formulas will be explained in detail below:

[0060] (1) Establish the following Figure 4 Based on the rectangular coordinate system shown and the experimental results, the expression for the water column trajectory is set as follows:

[0061] y = ax 2 +bx+c (4)

[0062] y′=2ax+b (5)

[0063] Assuming the water gun's ejection point is (0,0), the angle between the water gun and the horizontal plane is θ, and the target object's coordinates are (L,0), substituting these values, we can calculate:

[0064] b = tanθ, (6)

[0065] c = 0, (7)

[0066]

[0067] (2) Solve for the distance S that the water column travels in the air;

[0068] The formula for calculating the length of a parabola is as follows:

[0069]

[0070] Solving the integral yields the following formula:

[0071]

[0072] Substituting equations (6) and (8) into equation (10) yields

[0073]

[0074] Substituting equation (8) into equation (11) yields the following result:

[0075]

[0076] (3) Solve for the resistance value of the water column under safe conditions:

[0077] R = R L ·S (13)

[0078] R L =m1-m2Q+m3Q 2 (14)

[0079] Where: Q is the water jet volumetric flow rate, in m³ / s. 3 / h; Experimental tests showed that the resistance per unit distance of the water jet from the water gun decreases as the flow rate increases. Therefore, m1, m2, and m3 were obtained through experimental fitting.

[0080] (4) The minimum water column length L under the condition of human safety is calculated. S

[0081]

[0082] Among them: U P The DC voltage at the point where the photovoltaic fire started, in V;

[0083] R S The electrical resistance of the human body, measured in Ω.

[0084] U S The safe voltage for the human body, unit: V;

[0085] To ensure human safety, the following conditions must be met:

[0086] S≥L S (16)

[0087] (5) Calculate and determine the minimum safe distance for extinguishing live electrical fires.

[0088] Substituting equation (11) into equation (16) yields the expression for the minimum safe distance:

[0089]

[0090] Please see Figure 2 A system for obtaining a safe distance when using a water cannon to extinguish a photovoltaic fire, comprising:

[0091] The first parameter acquisition module acquires the water gun's volumetric flow rate Q in real time and infers the resistance value R per unit distance of the water jet from the water gun based on the water gun's volumetric flow rate Q. L When Q is in the range of 5 to 12m 3 When / h, the calculation formula is:

[0092] R L =m1+m2Q+m3Q 2 (1)

[0093] Wherein: R L The resistance of the water jet per unit distance from the water gun is Ω / m; Q is the volumetric flow rate of the water gun, in m³ / s. 3 / h; m1, m2, and m3 are experimental fitting constants; in this embodiment, m1 = 7787.97, m2 = -850.33, and m3 = 25.53, which were obtained through fitting calculations in multiple experiments.

[0094] Second parameter acquisition module: Real-time acquisition of DC voltage U at the photovoltaic fire site. P Human body resistance R S Safety voltage U S Parameters, and based on the DC voltage U P Human body resistance R S Safety voltage U S Reasoning for the minimum length L of the water jet ejected from the water gun under safe voltage conditions. S The calculation formula is:

[0095]

[0096] Where: L S The minimum length of the water jet ejected from the water gun under safe voltage conditions, in meters (m); U P The DC voltage at the point of origin of the fire in the photovoltaic power generation system, in V; U S The safe voltage for the human body, unit: V, usually taken as 36V; R S The resistance of the human body, measured in Ω, is typically taken as 2000Ω.

[0097] The third parameter acquisition module: Based on experimental results, the following water gun trajectory is derived, according to the minimum length L of the water jet under safe voltage conditions. S The minimum safe distance L for extinguishing live electrical fires is deduced, and the calculation formula is as follows:

[0098]

[0099] b = tanθ

[0100] Where: θ is the angle between the water gun and the horizontal plane, in rad; L is the minimum safe distance for extinguishing electric shocks, in m; the unit is rad.

[0101] Result output module: Obtain the safe distance L' when using a water gun to extinguish a photovoltaic fire, wherein the safe distance L' is not less than the minimum safe distance L.

[0102] A water gun, on which the aforementioned system for obtaining a safe distance when using the water gun to extinguish a photovoltaic fire is installed.

[0103] In one embodiment, the first parameter acquisition module includes a flow sensor installed on the water gun and a first calculation module that executes formula (1).

[0104] In one embodiment, the second parameter acquisition module includes a module for acquiring DC voltage U. P The voltage sensor and the second calculation module that executes formula (2).

[0105] In one embodiment, the third parameter acquisition module includes an angle measurement sensor mounted on the water gun and a third calculation module that executes formula (3).

[0106] To verify the effectiveness of formula (1), a system was built as follows: Figure 3 The photovoltaic module electrification firefighting test platform shown is mainly composed of a control box 1, a multi-stage pump 2, a water gun movement trajectory trolley 3, a photovoltaic grid 4, and a DC power supply. The control box includes a multi-stage pump control module, a water gun flow transmitter, a current transmitter, and a voltage transmitter, which are used for water pump control and data acquisition of current, voltage, and flow. The multi-stage pump provides a water gun pressure of 0-0.3MPa. The water gun movement trajectory trolley is used to adjust the distance between the water gun and the photovoltaic grid and to adjust the water gun angle. The photovoltaic grid and the DC power supply are interconnected and can provide a DC voltage of 0-1500V.

[0107] The experiment tested the voltage variation of the water gun head during live-line firefighting under different distances between the water gun and the photovoltaic grid. The distances between the water gun and the photovoltaic grid were 19.6m, 14.6m, 11.0m, and 8.2m, corresponding to a water gun flow rate of 16.86m³ / h. 3 / h, 13.71m 3 / h, 11.64m 3 / h, 9.83m 3 / h, the photovoltaic grid voltage is 300~1500V, and the test is performed every 50V. The water gun outlet pipe diameter is 2cm, and the angle between the water gun and the ground is 50 degrees. The experimental test results, calculation results, and relative errors are shown in Table 1 below.

[0108] Table 1. Resistance per unit length of water jet from water gun during live-fire suppression (Ω / m)

[0109]

[0110]

[0111] A computer program for implementing the method of obtaining a safe distance when using a water gun to extinguish a photovoltaic fire in the preferred embodiment described above.

[0112] An information data processing terminal that implements the method for obtaining a safe distance when using a water gun to extinguish a photovoltaic fire in the preferred embodiment described above.

[0113] A computer-readable storage medium includes instructions that, when executed on a computer, cause the computer to perform the method for obtaining a safe distance when using a water gun to extinguish a photovoltaic fire, as described in the preferred embodiment above.

[0114] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented, in whole or in part, as a computer program product, the computer program product includes one or more computer instructions. When the computer program instructions are loaded or executed on a computer, the processes or functions described in the embodiments of the present invention are generated, in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

[0115] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A method for obtaining a safe distance when using a water gun to extinguish a photovoltaic fire, characterized in that, include: S1. Obtain the water gun volumetric flow rate Q in real time, and infer the resistance value R per unit distance of the water jet sprayed from the water gun based on the water gun volumetric flow rate Q. L When Q is in the range of 5 to 12m 3 When / h, the calculation formula is: R L =m1+m2Q+m3Q 2 ; (1) S2. Real-time acquisition of DC voltage U at the location of the photovoltaic fire. P Human body resistance R S Safety voltage U S And according to the DC voltage U P Human body resistance R S Safety voltage U S Reasoning for the minimum length L of the water jet ejected from the water gun under safe voltage conditions. S The calculation formula is: S3. Based on the minimum length L of the water jet ejected by the water gun under safe voltage conditions. S The minimum safe distance L for extinguishing live electrical fires is deduced, and the calculation formula is as follows: b = tanθ Where: θ is the angle between the water gun and the horizontal plane, and the unit is rad; S4. Obtain the safe distance L' when using a water gun to extinguish a photovoltaic fire, wherein the safe distance L' is not less than the minimum safe distance L.

2. The method for obtaining a safe distance when using a water gun to extinguish a photovoltaic fire according to claim 1, characterized in that, m1=7787.97, m2=-850.33, m3=25.

53.

3. A system for obtaining a safe distance when using a water gun to extinguish a photovoltaic fire, characterized in that, include: The first parameter acquisition module acquires the water gun's volumetric flow rate Q in real time and obtains the resistance value R per unit distance of the water jet from the water gun based on the water gun's volumetric flow rate Q. L When Q is in the range of 5 to 12m 3 When / h, the calculation formula is: R L =m1+m2Q+m3Q 2 ; (1) Where m1, m2, and m3 are experimental fitting constants; Second parameter acquisition module: Real-time acquisition of DC voltage U at the photovoltaic fire site. P Human body resistance R S Safety voltage U S And according to the DC voltage U P Human body resistance R S Safety voltage U S Obtain the minimum length L of the water jet ejected by the water gun under safe voltage conditions. S The calculation formula is: The third parameter acquisition module: based on the minimum length L of the water jet ejected by the water gun under safe voltage conditions. S The minimum safe distance L for extinguishing live electrical fires is calculated using the following formula: b = tanθ Where: θ is the angle between the water gun and the horizontal plane, and the unit is rad; Result output module: Obtain the safe distance L' when using a water gun to extinguish a photovoltaic fire, wherein the safe distance L' is not less than the minimum safe distance L.

4. The system for obtaining a safe distance when using a water gun to extinguish a photovoltaic fire according to claim 3, characterized in that, m1=7787.97, m2=-850.33, m3=25.

53.

5. A water gun, characterized in that, The water gun is equipped with a system for obtaining a safe distance when using a water gun to extinguish a photovoltaic fire, as described in claim 3 or 4.

6. The water gun according to claim 5, characterized in that, The first parameter acquisition module includes a flow sensor installed on the water gun and a first calculation module that executes formula (1).

7. The water gun according to claim 5, characterized in that, The second parameter acquisition module includes a module for acquiring DC voltage U. P The voltage sensor and the second calculation module that executes formula (2).

8. The water gun according to claim 5, characterized in that, The third parameter acquisition module includes an angle measurement sensor installed on the water gun and a third calculation module that executes formula (3).

9. An information data processing terminal for implementing the method of obtaining a safe distance when using a water gun to extinguish a photovoltaic fire as described in claim 1 or 2.

10. A computer-readable storage medium comprising instructions, when executed on a computer, causing the computer to perform the method for obtaining a safe distance when using a water gun to extinguish a photovoltaic fire as described in claim 1 or 2.

Images