A fire area determination method and system based on photovoltaic module power generation characteristics

Abstract

The present invention discloses a method and system for determining a fire area based on the power generation characteristics of photovoltaic modules, belonging to the field of new energy technology, including: S1, obtaining basic parameters: the voltage calculation model fitting coefficient m of each module unit nm1 、m nm2 、m nm3 and m nm4 , heat release rate per unit time for each component unit h nmr 、The area of ​​each component unit A nm , thermal conductivity of each component unit t nmc , the current calculation model fitting coefficient n of each component unit nm1 、n nm2 、n nm3 and n nm4 、The voltage U of each component unit nm and load current I nm ; S2, filter the parameters of abnormal component units from the basic parameters, the abnormal component units are component units with abnormal changes in current and / or voltage; S3, calculate the distance from each abnormal component unit to the flame center using the following formula: S4, according to x nmu and x nmI Determine the fire area.

Description

Technical Field

[0001] The present invention belongs to the field of new energy technology, and in particular relates to a method and system for determining a fire area based on power generation characteristics of a photovoltaic module. Background Art

[0002] With the rapid development and widespread promotion of the photovoltaic industry, installed capacity has increased year by year, and inverters, combiner boxes, high-current components and application scenarios have become increasingly complex, resulting in an increase in fire hazards. According to statistics, the main fire sites are photovoltaic modules, distribution boxes, combiner boxes, inverters, etc., of which photovoltaic modules account for more than 50%. After the photovoltaic modules themselves burn, they will ignite other combustibles such as waterproof felt on the surrounding roofs, which can easily cause large-scale fires to spread.

[0003] According to the relevant design specifications of photovoltaic power generation systems, an automatic fire alarm system is designed. The most common detection method is the intelligent smoke detector, but this method is only applicable to the scene where the inverter is installed indoors. It is not applicable to photovoltaic power generation systems installed on roofs or walls. In the process of photovoltaic development, various types of fire detection methods have been introduced. For example, He Zengxiang and others from Southeast University proposed a photovoltaic power station fire detection system based on video monitoring, which can achieve early detection of photovoltaic fires based on the color characteristics and diffusion characteristics of smoke generated during the fire, and the color characteristics and flickering characteristics of flames; Jiang Lin and others from Hefei University of Technology proposed a photovoltaic array hot spot detection method based on the fusion of visible light and infrared thermal images; Kaplani E. and others used infrared thermal imagers to obtain infrared images of photovoltaic arrays, and then judged whether the photovoltaic arrays had similar hot spots, aging and other faults based on the temperature changes of photovoltaic modules under different working conditions. Benatto GADR and others used drones to take electroluminescent images of photovoltaic arrays under high irradiance conditions, and identified faults related to power loss through image information. Based on the method of injecting current into photovoltaic cells to obtain lateral power loss, Breitenstein O. et al. proposed phase-locked thermal imaging to detect leakage faults of photovoltaic cells. Haunschild J. et al. used photovoltaic power generation technology to detect the low efficiency defects of photovoltaic cells. Chakrapani SK et al. used Lamb wave air-coupled ultrasonic detection technology to quickly detect the cracks of photovoltaic module cells. Existing detection and alarm methods are summarized into three categories, namely fire detection based on video surveillance, infrared sensing detection, and temperature sensing cable detection. The use of each method will result in a sharp increase in cost and prone to false alarms or delayed alarms, which delays the golden time for photovoltaic fire fighting. Summary of the invention

[0004] In view of the defects of the prior art, the present invention provides a fire early detection and warning method and system based on the power generation characteristics of photovoltaic modules. The fire is determined by the fact that the photovoltaic modules will show different power generation characteristics under the irradiation of flames than under the irradiation of sunlight. At the same time, the location of the fire is determined based on the difference in power generation characteristics at different distances from the fire.

[0005] The specific technical solution adopted by the present invention is:

[0006] The first invention purpose of this patent is to provide a method for determining a fire area based on the power generation characteristics of a photovoltaic module, wherein the photovoltaic module includes M rows and N columns of module units; the method for determining a fire area includes:

[0007] S1. Obtain basic parameters: voltage calculation model fitting coefficient m for each component unit nm1 、m nm2 、m nm3 and m nm4 , heat release rate per unit time for each component unit h nmr 、The area of ​​each component unit A nm , thermal conductivity of each component unit t nmc , the current calculation model fitting coefficient n of each component unit nm1 、n nm2 、n nm3 and n nm4 、The voltage U of each component unit nm and load current I nm ; m is an integer from 1 to M, and n is an integer from 1 to N;

[0008] S2. Filtering parameters of abnormal component units from basic parameters, wherein the abnormal component units are component units with abnormal changes in current and / or voltage;

[0009] S3. For abnormal component units, use the following formula to calculate the distance from each abnormal component unit to the flame center:

[0010]

[0011] Where: x nmu is the voltage U passing through the abnormal component unit in the nth row and mth column nm The distance from the abnormal component unit to the flame center is obtained; x nmI is the load current I passing through the abnormal component unit in the nth row and mth column nm The obtained distance from the abnormal component unit to the flame center;

[0012] S4, according to x nmu and x nmI Identify the fire area;

[0013] The expressions for the fire area coordinates are as follows:

[0014]

[0015] Where: (x, y) is the coordinate of the fire area, (x n ,y m ) is the center coordinate of the abnormal component unit in the nth row and mth column when the current and / or voltage changes abnormally, is the distance from the fire source calculated by the component unit in the nth row and the mth column according to the current change, is the distance from the fire source calculated based on the voltage change of the module unit in the nth row and the mth column, n and m are the numbers of the abnormal module unit on the x-axis and y-axis in the PV module, respectively, the maximum value of n and m is the maximum number of PV modules with current and / or voltage changes, L and W are the lengths of the PV module projected on the ground or roof along the x-axis and y-axis, respectively, in meters;

[0016] Through the expression of the fire area coordinates, we can get several circles with the center coordinates of the abnormal component unit as the center and x as the center. nmu and x nmI A sphere with a radius of 1.040. The intersecting or overlapping part of several spheres is the fire area.

[0017] Preferably, m nm1 、m nm2 、m nm3 and m nm4 The corresponding values ​​are 32.49226, -0.26787, -32.88349, 1.72023, n nm1 、n nm2 、n nm3 and n nm4 The corresponding values ​​are 0.835412, 17.2653, -0.790893, and 67.5704.

[0018] Preferably, in S2, the method for screening abnormal component units is: under sunshine conditions, when the voltage of some component units increases abnormally or the voltage of some component units drops to 0 instantly, they are determined to be abnormal components.

[0019] Preferably, in S2, the method for screening abnormal component units is: when the voltage or current of some component units is abnormal under the condition of no sunshine, they are determined to be abnormal components.

[0020] A second object of the present invention is to provide a fire area determination system based on photovoltaic module power generation characteristics, comprising:

[0021] Data acquisition module, voltage calculation model fitting coefficient m for each component unitnm1 、m nm2 、m nm3 and m nm4 , heat release rate per unit time for each component unit h nmr 、The area of ​​each component unit A nm , thermal conductivity of each component unit t nmc , the current calculation model fitting coefficient n of each component unit nm1 、n nm2 、n nm3 and n nm4 、The voltage U of each component unit nm and load current I nm ; m is an integer from 1 to M, and n is an integer from 1 to N;

[0022] A screening module, screening parameters of abnormal component units from the basic parameters, wherein the abnormal component units are component units with abnormal changes in current and / or voltage;

[0023] The calculation module calculates the distance from each abnormal component unit to the flame center using the following formula for the abnormal component unit:

[0024]

[0025] Where: x nmu is the voltage U passing through the abnormal component unit in the nth row and mth column nm The distance from the abnormal component unit to the flame center is obtained; x nmI is the load current I passing through the abnormal component unit in the nth row and mth column nm The obtained distance from the abnormal component unit to the flame center;

[0026] Determine the module, according to x nmu and x nmI Identify the fire area;

[0027] The expressions for the fire area coordinates are as follows:

[0028]

[0029] Where: (x, y) is the coordinate of the fire area, (x n ,y m ) is the center coordinate of the abnormal component unit in the nth row and mth column when the current and / or voltage changes abnormally, is the distance from the fire source calculated by the component unit in the nth row and the mth column according to the current change, is the distance from the fire source calculated based on the voltage change of the module unit in the nth row and the mth column, n and m are the numbers of the abnormal module unit on the x-axis and y-axis in the PV module, respectively, the maximum value of n and m is the maximum number of PV modules with current and / or voltage changes, L and W are the lengths of the PV module projected on the ground or roof along the x-axis and y-axis, respectively, in meters;

[0030] Through the expression of the fire area coordinates, we can get several circles with the center coordinates of the abnormal component unit as the center and x as the center. nmu and x nmI A sphere with a radius of 1.040. The intersecting or overlapping part of several spheres is the fire area.

[0031] Preferably, m nm1 、m nm2 、m nm3 and m nm4 The corresponding values ​​are 32.49226, -0.26787, -32.88349, 1.72023, n nm1 、n nm2 、n nm3 and n nm4 The corresponding values ​​are 0.835412, 17.2653, -0.790893, and 67.5704.

[0032] Preferably, in the screening module, the screening method for abnormal component units is: under sunshine conditions, when the voltage of some component units increases abnormally or the voltage of some component units drops to 0 instantly, they are determined to be abnormal components.

[0033] Preferably, in the screening module, the screening method for abnormal component units is: when the voltage or current of some component units is abnormal under the condition of no sunshine, they are determined to be abnormal components.

[0034] The third invention objective of this patent is to provide a computer program that implements the above-mentioned method for determining the fire area based on the power generation characteristics of photovoltaic modules.

[0035] The fourth invention objective of this patent is to provide an information data processing terminal that implements the above-mentioned fire area determination method based on the power generation characteristics of photovoltaic modules.

[0036] The fifth invention objective of this patent is to provide a computer-readable storage medium, including instructions, which, when run on a computer, enables the computer to execute the above-mentioned fire area determination method based on the power generation characteristics of photovoltaic modules.

[0037] The advantages and positive effects of the present invention are:

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

[0039] The present invention determines whether a fire has occurred by taking advantage of the fact that photovoltaic modules will exhibit power generation characteristics different from those under sunlight when exposed to flames. At the same time, based on the differences in power generation characteristics at different distances from the fire, the location of the fire is determined. The basic data extracted by the method proposed in the patent can be obtained through the data in the junction box and inverter, or by installing a small data acquisition device on the back of the photovoltaic module. This application overcomes the shortcomings of traditional fire alarm detection, and the cost is lower than that of video, infrared imaging and other means. The false alarm rate of detection is less than 10%, which can effectively reduce the probability of large-scale fire spread accidents in photovoltaic modules and enhance the fire safety reliability of photovoltaic power generation systems.

[0040] The technical solution of the present application can be directly applied to photovoltaic power stations. By using this technology in unmanned places or places such as rooftops where daily inspections by personnel are difficult, it can effectively monitor and identify fires in photovoltaic modules. At the same time, the specific location information of the fire can be predicted according to the formula, which facilitates the rapid positioning of the fire and accurately extinguishes the photovoltaic fire. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is the equivalent circuit diagram of the photovoltaic module;

[0042] Figure 2 It is a structural diagram of the experimental platform in the preferred embodiment of the present invention;

[0043] Figure 3 This is a voltage fitting comparison result diagram under the condition of 1.0m test distance in the preferred embodiment of the present invention;

[0044] Figure 4 This is a current fitting comparison result diagram under the condition of a test distance of 1.0m in a preferred embodiment of the present invention;

[0045] Figure 5 This is a voltage fitting comparison result diagram under the condition of a test distance of 2.0m in a preferred embodiment of the present invention;

[0046] Figure 6 This is a current fitting comparison result diagram under the condition of a test distance of 2.0m in a preferred embodiment of the present invention;

[0047] Figure 7 This is a schematic diagram of region determination in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0048] In order to further understand the content, features and effects of the present invention, the following embodiments are given as examples and described in detail with reference to the accompanying drawings.

[0049] The structure of the present invention is described in detail below in conjunction with the accompanying drawings.

[0050] Working principle and basic mathematical model of photovoltaic module power generation:

[0051] When the energy of sunlight irradiating the cathode surface of the photovoltaic module battery is greater than the ground state energy of the electron, the electron will undergo a transition, that is, the photon is converted into an electron, which is the photovoltaic effect. During the electron transition process, the anode of the photovoltaic module battery will induce positive charges, that is, holes. The N region gathers a large amount of negative charges, so it is negatively charged to the outside. The P region induces a large amount of positive charges, so it is positively charged to the outside. Since the N region and the P region eventually form a certain concentration difference, a diffusion movement from high concentration to low concentration will occur between the N region and the P region. Finally, an electric field pointing from N to P will be generated between the N region and the P region, which is also the process of PN junction formation.

[0052] The formation of the internal electric field will hinder the diffusion of the original particles, causing the diffusion direction of the original particles to move in the opposite direction of the diffusion, that is, the drift movement of the particles. Eventually, the diffusion of the majority carriers and the drift of the minority carriers reach a balance. A stable potential difference is formed. The area close to the P area is the positive pole of the photovoltaic module, and the area close to the N area is the negative pole of the photovoltaic module. The part between the P area and the N area is called the internal circuit of the photovoltaic module. The external circuit of the photovoltaic module consists of wires and loads. The positive and negative poles of the photovoltaic module can be connected through wires and loads. The direction of the internal electromotive force is from N to P, and the current of the external circuit flows from the positive pole of the photovoltaic module to the negative pole through the load. The above description is the working principle of a single photovoltaic module when generating electricity. Usually, in order to improve the power generation capacity of photovoltaic modules, we can connect single photovoltaic modules in series and parallel to form photovoltaic modules, and continue to connect photovoltaic modules in series and parallel to form photovoltaic arrays.

[0053] The equivalent circuit model of the photovoltaic module consists of a photovoltaic power source, a diode and a load. The equivalent circuit diagram is as follows: Figure 1 As shown in the figure. sh and R s are the internal equivalent parallel resistance and series resistance respectively, R is the external resistance of the photovoltaic module, V is the voltage across the resistor R, and also serves as the output voltage of the photovoltaic module. Figure 1 Middle I ph The photocurrent generated by photons in a photovoltaic module under sunlight is proportional to the intensity of sunlight radiation and increases slightly with the increase of temperature. In addition, the photocurrent is related to its own battery area. Generally speaking, the I of a 21cm silicon photovoltaic module under standard test conditions is ph The value is about 16~30mA. When the temperature rises by 1℃, I sc The value will rise by 78μA.

[0054] Figure 1 Middle I d is the diode current, and its direction is the same as the photocurrent I ph Instead, the expression is:

[0055]

[0056] Where: q is the charge of the electron, 1.6×10 -19 C;

[0057] K is the Boltzmann constant, 1.38×10 -23 J / K;

[0058] A is a constant factor.

[0059] From formula (1), we know that the diode current I d The size of is related to the electromotive force E and temperature T of the photovoltaic module.

[0060] according to Figure 1 The expression of load current I can be obtained as:

[0061]

[0062] Since formula (2) is a transcendental equation, in order to solve and analyze the power generation characteristics of photovoltaic modules, formula (2) is simplified to obtain an exponential model based on the power function model. First, the power law relationship is used to establish the relationship between the output current and voltage. Secondly, based on the technical reference value under the standard test conditions, the short-circuit current I is calculated at any light intensity and temperature. sc , open circuit voltage U oc , Maximum power point current I m With voltage U m The specific functional relationship is as follows:

[0063]

[0064]

[0065] In formula (3) to formula (7), d1, d2, f1, and f2 are the corresponding short-circuit current temperature coefficient, open-circuit voltage temperature coefficient, maximum power point current temperature coefficient, and voltage temperature coefficient, respectively. After the basic parameter information of the open-circuit voltage, short-circuit current, maximum operating point voltage, and maximum operating point current of the photovoltaic module under standard lighting conditions is known, it can be substituted into formula (3) to calculate the power generation characteristics of the photovoltaic module under any light intensity and temperature.

[0066] The flame wavelength produced by the combustion of combustibles is concentrated in the range of greater than 1000nm, with a peak value in the range of 1470 to 5000nm. Photovoltaic modules are most likely to absorb light waves between 500 and 800nm. The power generation characteristic model of photovoltaic modules under fire conditions is different from the characteristic change law under natural lighting conditions. Retain the exponential function expression and establish a calculation model for the power generation characteristics of photovoltaic modules under fire conditions. The function expression is as follows:

[0067]

[0068] Among them, U is the PV module voltage, unit: V; I is the PV module current, unit: A; W is the flame illumination, unit: W / ㎡; m1, m2, m3, m4 are the fitting coefficients of the voltage calculation model, and the corresponding values ​​are 32.49226, -0.26787, -32.88349, 1.72023; n1, n2, n3, n4 are the fitting coefficients of the current calculation model, and the corresponding values ​​are 0.835412, 17.2653, -0.790893, 67.5704.

[0069] Using a single point source model, that is, assuming that the fire source is considered to be composed of ignition sources concentrated at one point, the incident radiation intensity at a certain distance (x) from the center of the flame is:

[0070]

[0071] Where:

[0072] h r is the heat release rate per unit time, W / ㎡;

[0073] A is the area of ​​PV modules, m2;

[0074] W is the thermal radiation intensity, W / m 2 ;

[0075] t c is the heat transfer coefficient, which can be taken as 1 when there is no relatively ideal data;

[0076] x is the distance from the PV module to the flame center, m.

[0077] By combining equations (8), (9) and (10), we can solve the expression of the distance x from the photovoltaic module to the flame center, as shown below:

[0078]

[0079] Where: x u is the distance from the PV module to the flame center obtained based on the PV module voltage U; x I is the distance from the PV module to the flame center obtained based on the load current I;

[0080] A method for determining a fire area based on power generation characteristics of a photovoltaic module, wherein the photovoltaic module includes module units of M rows and N columns; the method for determining a fire area includes:

[0081] S1. Get basic parameters:

[0082] The voltage calculation model fitting coefficient m for each component unit nm1 、m nm2 , and

[0083] The heat release rate per unit time of each component unit h nmr ;

[0084] The area of ​​each module unit is A nm ;

[0085] The thermal conductivity of each component unit t nmc ;

[0086] The current calculation model fitting coefficient n of each component unit nm1 、n nm2 、n nm3 and n nm4 ;

[0087] Voltage U per module unit nm and load current I nm ;

[0088] m is an integer from 1 to M, and n is an integer from 1 to N;

[0089] S2. Filtering parameters of abnormal component units from basic parameters, wherein the abnormal component units are component units with abnormal changes in current and / or voltage; the screening of abnormal component units is divided into two situations: with sunshine and without sunshine; wherein:

[0090] The screening method for abnormal component units is as follows: under sunshine conditions, the photovoltaic components' response to fire source light under sunshine conditions is mainly reflected in the abnormal increase in voltage, and the impact on current does not change significantly; therefore, when the voltage of some component units increases abnormally or the voltage of some component units drops to 0 instantly, they are judged as abnormal components, and the abnormality here is defined as fire.

[0091] The screening method for abnormal component units is: when the voltage or current of some component units is abnormal under the condition of no sunshine, they are judged as abnormal components.

[0092] S3. For abnormal component units, use the following formula to calculate the distance from each abnormal component unit to the flame center:

[0093]

[0094] Where: x nmu is the voltage U passing through the abnormal component unit in the nth row and mth column nm The distance from the abnormal component unit to the flame center is obtained; x nmI is the load current I passing through the abnormal component unit in the nth row and mth columnnm The obtained distance from the abnormal component unit to the flame center;

[0095] S4, according to x nmu and x nmI Identify the fire area;

[0096] The expressions for the fire area coordinates are as follows:

[0097]

[0098] Where: (x, y) is the coordinate of the fire area, (x n ,y m ) is the center coordinate of the abnormal component unit in the nth row and mth column when the current and / or voltage changes abnormally, is the distance from the fire source calculated by the component unit in the nth row and the mth column according to the current change, is the distance from the fire source calculated based on the voltage change of the component unit in the nth row and the mth column. n and m are the numbers of the abnormal component unit on the x-axis and y-axis in the PV module, respectively. The maximum values ​​of n and m are the maximum number of PV modules that experience current and / or voltage changes. L and W are the lengths of the projection of the PV module on the ground or roof along the x-axis and y-axis, respectively, in meters. The above coordinate axes are parallel to the ground or roof where the PV is installed.

[0099] Through the expression of the fire area coordinates, we can get several circles with the center coordinates of the abnormal component unit as the center and x as the center. nmu and x nmI A sphere with a radius of 1.040. The intersecting or overlapping part of several spheres is the fire area.

[0100] Since photovoltaic modules in photovoltaic power generation systems are installed and laid in a continuous manner, when a fire occurs, it will cause changes in the current and voltage of the module units around the fire site. By calculating the changes in current and voltage, the distance of each abnormal module unit from the fire source is calculated. With the center of the photovoltaic module where the current and voltage change, the calculated distance from the fire source is used as the radius to draw a circle. The intersecting or overlapping part of the circles is the fire area. Figure 7 shown.

[0101] m nm1 、m nm2 , and The corresponding values ​​are 32.49226, -0.26787, -32.88349, 1.72023, n nm1 、n nm2 、n nm3 and n nm4The corresponding values ​​are 0.835412, 17.2653, -0.790893, and 67.5704.

[0102] A fire area determination system based on photovoltaic module power generation characteristics, comprising:

[0103] Data acquisition module, voltage calculation model fitting coefficient m for each component unit nm1 、m nm2 , and The heat release rate per unit time of each component unit h nmr 、The area of ​​each component unit A nm , thermal conductivity of each component unit t nmc , the current calculation model fitting coefficient n of each component unit nm1 、n nm2 、n nm3 and n nm4 、The voltage U of each component unit nm and load current I nm ; m is an integer from 1 to M, and n is an integer from 1 to N;

[0104] A screening module is used to screen the parameters of abnormal component units from the basic parameters, wherein the abnormal component units are component units with abnormal changes in current and / or voltage; the screening of abnormal component units is divided into two situations: with sunshine and without sunshine; wherein:

[0105] The screening method for abnormal component units is as follows: under sunshine conditions, the photovoltaic components' response to fire source light under sunshine conditions is mainly reflected in the abnormal increase in voltage, and the impact on current does not change significantly; therefore, when the voltage of some component units increases abnormally or the voltage of some component units drops to 0 instantly, they are judged as abnormal components, and the abnormality here is defined as fire.

[0106] The screening method for abnormal component units is: when the voltage or current of some component units is abnormal under the condition of no sunshine, they are judged as abnormal components.

[0107] The calculation module calculates the distance from each abnormal component unit to the flame center using the following formula for the abnormal component unit:

[0108]

[0109] Where: x nmu is the voltage U passing through the abnormal component unit in the nth row and mth column nm The distance from the abnormal component unit to the flame center is obtained; x nmI is the load current I passing through the abnormal component unit in the nth row and mth column nmThe obtained distance from the abnormal component unit to the flame center;

[0110] Determine the module, according to x nmu and x nmI Identify the fire area;

[0111] The expressions for the fire area coordinates are as follows:

[0112]

[0113] Where: (x, y) is the coordinate of the fire area, (x n ,y m ) is the center coordinate of the abnormal component unit in the nth row and mth column when the current and / or voltage changes abnormally, is the distance from the fire source calculated by the component unit in the nth row and the mth column according to the current change, is the distance from the fire source calculated based on the voltage change of the module unit in the nth row and the mth column, n and m are the numbers of the abnormal module unit on the x-axis and y-axis in the PV module, respectively, the maximum value of n and m is the maximum number of PV modules with current and / or voltage changes, L and W are the lengths of the PV module projected on the ground or roof along the x-axis and y-axis, respectively, in meters;

[0114] Through the expression of the fire area coordinates, we can get several circles with the center coordinates of the abnormal component unit as the center and x as the center. nmu and x nmI A sphere with a radius of 1.040. The intersecting or overlapping part of several spheres is the fire area.

[0115] m nm1 、m nm2 , and The corresponding values ​​are 32.49226, -0.26787, -32.88349, 1.72023, n nm1 、n nm2 、n nm3 and n nm4 The corresponding values ​​are 0.835412, 17.2653, -0.790893, and 67.5704.

[0116] In the screening module, the screening method for abnormal component units is: under sunshine conditions, when the voltage of some component units increases abnormally or the voltage of some component units drops to 0 instantly, they are judged as abnormal components.

[0117] In the screening module, the screening method for abnormal component units is: when the voltage or current of some component units is abnormal under the condition of no sunshine, it is judged as abnormal component.

[0118] To verify the validity of formula (8) and formula (9), the following experimental platform can be built to test the validity of the calculation of the power generation characteristics of photovoltaic modules under fire conditions. The experimental platform is mainly composed of fire source 1, photovoltaic module 2, load, current and voltage data acquisition equipment, as follows Figure 2 As shown. The fire source is 92# gasoline poured into a 1.5m diameter disc, and the gasoline is ignited as the fire source. The main reason for choosing the gasoline disc is that gasoline has a high calorific value and is very flammable. After ignition, it will quickly enter the stable combustion stage. The flame in the stable combustion stage is relatively stable, which is convenient for repeated experimental research. The photovoltaic module is selected as a 450W single-glass photovoltaic module with a size of 2094mm×1038mm×35mm and an inclination angle of 33.07°. The main function of the load is to consume the electrical energy generated by the photovoltaic module in the formed loop. The data acquisition equipment mainly includes light intensity sensors, current transmitters, voltage transmitters and paperless recorders. The distance between the center of the fire source and the bottom of the photovoltaic module is 1.0m and 2.0m.

[0119] The current and voltage experimental data are compared with the fitting function. Figures 3 to 6 As shown, based on the comparative calculation of formula (11) and formula (12), the prediction results of the 1.0m and 2.0m experiments are 1.1m and 2.15m respectively, with relative errors of 10% and 7.5%. Since the width of a single photovoltaic module is 1.1m, the prediction accuracy is sufficient to meet the positioning of a single module in engineering applications.

[0120] A computer program for implementing the fire area determination method based on the power generation characteristics of photovoltaic modules in the above preferred embodiment.

[0121] An information data processing terminal for implementing the fire area determination method based on photovoltaic module power generation characteristics in the above preferred embodiment.

[0122] A computer-readable storage medium includes instructions, which, when executed on a computer, enable the computer to execute the fire area determination method based on the power generation characteristics of photovoltaic modules in the above preferred embodiment.

[0123] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When the use is implemented in whole or in part in the form of 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 process or function described in the embodiment of the present invention is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from one website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL) or wireless (e.g., infrared, wireless, microwave, etc.) mode) to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state hard disk SolidState Disk (SSD)), etc.

[0124] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are within the scope of the technical solution of the present invention.

Claims

1. A method for determining a fire area based on the power generation characteristics of a photovoltaic module, wherein the photovoltaic module comprises module units of M rows and N columns; characterized in that: The fire area determination method comprises: S1. Obtain basic parameters: voltage calculation model fitting coefficient m for each component unit nm1 、m nm2 、m nm3 and m nm4 , heat release rate per unit time for each component unit h nmr 、The area of ​​each component unit A nm , thermal conductivity of each component unit t nmc , the current calculation model fitting coefficient n of each component unit nm1 、n nm2 、n nm3 and n nm4 、The voltage U of each component unit nm and load current I nm ; m is an integer from 1 to M, and n is an integer from 1 to N; S2. Filtering parameters of abnormal component units from basic parameters, wherein the abnormal component units are component units with abnormal changes in current and / or voltage; S3. For abnormal component units, use the following formula to calculate the distance from each abnormal component unit to the flame center: Where: x nmu is the voltage U passing through the abnormal component unit in the nth row and mth column nm The distance from the abnormal component unit to the flame center is obtained; x nmI is the load current I passing through the abnormal component unit in the nth row and mth column nm The obtained distance from the abnormal component unit to the flame center; S4, according to x nmu and x nmI Identify the fire area; The expressions for the fire area coordinates are as follows: Where: (x, y) is the coordinate of the fire area, (x n ,y m ) is the center coordinate of the abnormal component unit in the nth row and mth column when the current and / or voltage changes abnormally, is the distance from the fire source calculated by the component unit in the nth row and the mth column according to the current change, is the distance from the fire source calculated based on the voltage change of the module unit in the nth row and the mth column, n and m are the numbers of the abnormal module unit on the x-axis and y-axis in the PV module, respectively, the maximum value of n and m is the maximum number of PV modules with current and / or voltage changes, L and W are the lengths of the PV module projected on the ground or roof along the x-axis and y-axis, respectively, in meters; Through the expression of the fire area coordinates, we can get several circles with the center coordinates of the abnormal component unit as the center and x as the center. nmu and x nmI is a sphere with a radius of 1. The intersection or overlap of several spheres is the fire occurrence area. m nm1 、m nm2 、m nm3 and m nm4 The corresponding values ​​are 32.49226, -0.26787, -32.88349, 1.72023, n nm1 、n nm2 、n nm3 and n nm4 The corresponding values ​​are 0.835412, 17.2653, -0.790893, and 67.5704.

2. The method for determining a fire area based on the power generation characteristics of photovoltaic modules according to claim 1, characterized in that: In S2, the screening method of abnormal component units is: under the condition of sunshine, when the voltage of some component units increases abnormally or the voltage of some component units drops to 0 instantly, they are judged as abnormal components.

3. The method for determining a fire area based on the power generation characteristics of photovoltaic modules according to claim 1, characterized in that: In S2, the method for screening abnormal component units is: when the voltage or current of some component units is abnormal under the condition of no sunshine, they are judged as abnormal components.

4. A fire area determination system based on photovoltaic module power generation characteristics, characterized in that: include: Data acquisition module, voltage calculation model fitting coefficient m for each component unit nm1 、m nm2 、m nm3 and m nm4 , heat release rate per unit time for each component unit h nmr 、The area of ​​each component unit A nm , thermal conductivity of each component unit t nmc , the current calculation model fitting coefficient n of each component unit nm1 、n nm2 、n nm3 and n nm4 、The voltage U of each component unit nm and load current I nm ; m is an integer from 1 to M, and n is an integer from 1 to N; A screening module, screening parameters of abnormal component units from the basic parameters, wherein the abnormal component units are component units with abnormal changes in current and / or voltage; The calculation module calculates the distance from each abnormal component unit to the flame center using the following formula for the abnormal component unit: Where: x nmu is the voltage U passing through the abnormal component unit in the nth row and mth column nm The distance from the abnormal component unit to the flame center is obtained; x nmI is the load current I passing through the abnormal component unit in the nth row and mth column nm The obtained distance from the abnormal component unit to the flame center; Determine the module, according to x nmu and x nmI Identify the fire area; The expressions for the fire area coordinates are as follows: Where: (x, y) is the coordinate of the fire area, (x n ,y m ) is the center coordinate of the abnormal component unit in the nth row and mth column when the current and / or voltage changes abnormally, is the distance from the fire source calculated by the component unit in the nth row and the mth column according to the current change, is the distance from the fire source calculated based on the voltage change of the module unit in the nth row and the mth column, n and m are the numbers of the abnormal module unit on the x-axis and y-axis in the PV module, respectively, the maximum value of n and m is the maximum number of PV modules with current and / or voltage changes, L and W are the lengths of the PV module projected on the ground or roof along the x-axis and y-axis, respectively, in meters; Through the expression of the fire area coordinates, we can get several circles with the center coordinates of the abnormal component unit as the center and x as the center. nmu and x nmI is a sphere with a radius of 1. The intersection or overlap of several spheres is the fire occurrence area. m nm1 、m nm2 、m nm3 and m nm4 The corresponding values ​​are 32.49226, -0.26787, -32.88349, 1.72023, n nm1 、n nm2 、n nm3 and n nm4 The corresponding values ​​are 0.835412, 17.2653, -0.790893, and 67.5704.

5. The fire area determination system based on photovoltaic module power generation characteristics according to claim 4 is characterized in that: In the screening module, the screening method for abnormal component units is: under sunshine conditions, when the voltage of some component units increases abnormally or the voltage of some component units drops to 0 instantly, they are judged as abnormal components.

6. The fire area determination system based on photovoltaic module power generation characteristics according to claim 4, characterized in that: In the screening module, the screening method for abnormal component units is: when the voltage or current of some component units is abnormal under the condition of no sunshine, they are judged as abnormal components.

7. An information data processing terminal for implementing the method for determining a fire area based on the power generation characteristics of photovoltaic modules as described in any one of claims 1 to 3.

8. A computer-readable storage medium comprising instructions, which, when executed on a computer, enables the computer to execute the method for determining a fire area based on power generation characteristics of photovoltaic modules as claimed in any one of claims 1 to 3.

Images