Fire risk assessment method for solar roof photovoltaic power generation system

Abstract

According to the fire risk assessment method for the solar roof photovoltaic power generation system, firstly, the identification of the fire risk dangerous source of the SRPS equipment is completed by analyzing the equipment characteristics of the SRPS system and constructing a pre-danger analysis method, and practical guidance is provided for roof photovoltaic fire protection; for the fact that probability data cannot be accurately obtained during quantitative analysis of a fire risk hazard source of the SRPS equipment, chaotic entropy is introduced to be combined with accident tree evaluation analysis, and quantitative analysis of the fire risk of the SRPS equipment is successfully completed. And secondly, the identified hazard sources are classified according to design, installation and operation stages, the hazard sources in different stages are analyzed by using a system whole life cycle method, an analysis control mode is provided, and a risk control system is constructed. And a safety check table is designed and formulated for dangerous sources during operation, so that the fire risk and loss of the SRPS equipment are greatly reduced, and large-scale popularization and application of the solar roof photovoltaic power generation system are facilitated.

Description

Technical Field

[0001] The present application relates to a fire risk assessment method for rooftop photovoltaic power generation, and in particular to a fire risk assessment method for a solar rooftop photovoltaic power generation (SRPS) system, belonging to the technical field of photovoltaic power generation fire assessment. Background Art

[0002] Currently, new energy represented by solar energy is widely favored. As an application form of solar power generation, photovoltaic building integration continues to grow and develop with the maturity of technology and the need for the development of green buildings.

[0003] With the continuous development of rooftop photovoltaic power generation systems, fire accidents have also continued to occur. This not only causes damage to the photovoltaic system itself, but also poses a safety hazard to the building itself and the people and property inside the building because of its combination with the building. In recent years, there have been many fire risk accidents in photovoltaic systems. These accidents have not only had a great impact on the photovoltaic system, but also caused casualties and property losses to varying degrees. Therefore, fire accidents in rooftop photovoltaic power generation equipment need to be taken seriously and analyzed.

[0004] Since there is little research on fire risks in rooftop photovoltaic systems, the research on its fire risk focuses on the factors that cause fire accidents in different components of rooftop photovoltaic systems. On the other hand, the research is aimed at identifying the causes of system fire accidents. There is a lack of systematic and targeted research on identifying the hazardous sources of fire accidents, and there is even less research on the fire risk assessment of the system.

[0005] The problems that need to be solved in the fire risk assessment of rooftop photovoltaic power generation systems in the prior art and the key technical difficulties of this application include:

[0006] (1) Fire accidents in rooftop photovoltaic power generation systems continue to occur, which not only causes damage to the photovoltaic system itself, but also poses safety hazards to the building itself and the people and property in the building, causing casualties and property losses to varying degrees. Fire accidents in rooftop photovoltaic power generation equipment urgently need to be carefully studied and analyzed. The existing technology does not clearly understand the causes of frequent fire-related failures in rooftop photovoltaic equipment, cannot scientifically and effectively identify the hazardous source elements of its fire risk accidents, cannot conduct risk assessment, and lacks targeted risk control methods. There is a lack of research on the characteristics of rooftop photovoltaic power generation systems and the characteristics of their fire accidents, and it is impossible to identify the source of danger and provide a foundation and support for risk control. There is a lack of risk control measures based on the identification of hazardous source elements of fire risk accidents. The existing technology has little research on fire risks in rooftop photovoltaic systems, lacks systematic and targeted research on identifying the hazardous sources of fire accidents, and lacks a systematic and effective method for assessing and preventing fire risks in rooftop photovoltaic power generation systems.

[0007] (2) Existing technologies are unable to identify fire hazards in rooftop photovoltaic power generation systems, and lack corresponding management and control methods and methods to reduce losses and transfer risks. There is a lack of pre-hazard analysis to identify the fire risk of SRPS equipment; due to the lack of basic data, it is impossible to quantitatively analyze the fire risk of SRPS equipment. There is a lack of post-targeted risk control measures analysis based on hazard source identification, and it is impossible to establish a targeted risk management and control system. Due to the inability to accurately obtain probability data when conducting quantitative analysis of fire risk hazards in rooftop photovoltaic power generation equipment, it is impossible to complete the quantitative analysis of SRPS equipment fire risks. There is a lack of SRPS system full life cycle method to analyze the hazards at different stages, and it is impossible to build a SRPS equipment risk control system.

[0008] (3) The existing technology lacks the identification and analysis and evaluation of the hazard sources of fire risk accidents of rooftop photovoltaic power generation equipment, and is unable to build a system life cycle risk control system. It lacks the analysis of rooftop photovoltaic power generation systems and their fire risks, and cannot qualitatively identify the risk sources of fire risk of building rooftop photovoltaic power generation equipment, and quantitatively analyze and evaluate them. It is impossible to obtain effective probabilities for each basic event of SRPS equipment fire risk, and it is impossible to achieve quantitative analysis and evaluation of SRPS equipment fire risk hazard sources, and it is impossible to determine the probability importance of each basic event; it is impossible to classify the hazard sources according to the system formation time, and there is a lack of targeted risk control methods for different hazard sources in different periods, and it is impossible to eliminate fire risks in daily maintenance. For fire accidents that cannot be eliminated, there is a lack of risk transfer methods, and it is impossible to reduce the losses caused by fire accidents. Since the existing technology lacks effective methods for fire risk assessment and prevention of rooftop photovoltaic power generation systems, it not only causes damage to the use of photovoltaic systems, but also brings safety hazards to the buildings themselves and the people and property in the buildings, which seriously hinders the development of rooftop photovoltaic power generation systems. Summary of the invention

[0009] This application analyzes and clarifies the reasons for the frequent fire failures of rooftop photovoltaic equipment, with the aim of using scientific and effective methods to identify the hazardous source elements of fire risk accidents, conduct risk assessment, and propose targeted risk control methods. Combined with the characteristics of rooftop photovoltaic power generation systems, based on the characteristics of fire accidents, identify the source of danger, provide a foundation and support for subsequent risk control, and provide scientific guidance for reducing the losses of fire accidents in rooftop photovoltaic power generation systems. By identifying the hazardous source elements of fire risk accidents of building rooftop photovoltaic equipment, risk control measures are proposed, and the content of management and control of fire risk accidents of building rooftop photovoltaic equipment is improved. According to the theoretical system of risk management and control, combined with the characteristics of system structure and engineering practice, the focus is on identifying and evaluating the hazardous source elements that cause fire risks, and analyzing and studying the control measures, and proposing targeted safety operation checklists and ways to transfer risks using insurance. A set of efficient and complete fire risk assessment system for rooftop photovoltaic power generation systems has been established, which has greatly reduced the fire risk and losses of SRPS equipment, and is conducive to the large-scale promotion and application of solar rooftop photovoltaic power generation systems.

[0010] In order to achieve the above technical effects, the technical solutions adopted in this application are as follows:

[0011] The fire risk assessment method of solar roof photovoltaic power generation system is to identify, analyze and evaluate the hazard sources of fire risk accidents of building roof photovoltaic power generation equipment, and build a system life cycle risk control system according to its characteristics. First, the roof photovoltaic power generation system and its fire risk are analyzed, and the hazard sources of fire risk of roof photovoltaic power generation equipment are qualitatively identified based on the pre-analysis of hazard sources. The chaotic accident tree evaluation analysis is used for quantitative analysis and evaluation, and the chaotic accident tree evaluation analysis is constructed to solve the problem that the fire risk probability data is difficult to obtain, and the quantitative analysis and evaluation of the SRPS equipment fire risk hazard sources are completed to determine the probability importance of each basic event; for the identified hazard sources, the hazard sources are classified according to the system formation time, and targeted risk control methods are established for different hazard sources in different periods. At the same time, for the built and operated SRPS, a SRPS equipment fire risk safety checklist is established. Through the components and applications of the safety checklist, the fire risk is eliminated in daily maintenance. Finally, for fire accidents that cannot be eliminated, the risk is transferred through insurance to eliminate or reduce the losses caused by fire accidents.

[0012] 1) Identification of fire risk factors of SRPS equipment: First, classify the fire risk sources of SRPS equipment, and build a hazard level classification based on severity and frequency according to the characteristics of the fire risk sources of SRPS equipment. Then, analyze the fire risk of the SRPS system from the perspective of different equipment. Finally, use the hazard source estimation method to conduct a qualitative analysis of its fire accidents. Based on the identification of the fire risk sources of SRPS equipment, qualitatively determine the cause of the fire and its risk level;

[0013] 2) SRPS equipment fire risk assessment: Chaos accident tree evaluation analysis is used to quantitatively analyze and evaluate the fire risk sources of SRPS equipment. When constructing the chaos accident tree analysis, the ignition source of the SRPS equipment fire risk is first determined as the top event, and then the accident tree logic analysis diagram is gradually constructed. Qualitative analysis is performed according to the accident tree. After quantitative analysis of the SRPS equipment fire risk, an expert scoring table is constructed. Through questionnaire surveys, the language chaos value is converted into a probability value to obtain chaos probability data. Based on the chaos entropy, the probability data of each basic event is obtained, and quantitative analysis and evaluation are completed to determine the probability importance of the system fire risk source;

[0014] 3) Control of fire risks of SRPS equipment: From the perspective of the system life cycle, the hazard sources are classified according to the planning and design, transportation and installation, operation and maintenance time periods, and corresponding risk control measures are formulated. For the fire risk hazard sources during the operation period with the longest system life, a safety checklist is formulated to provide a plan for the routine prevention and control of hazard sources during this period.

[0015] Preferably, classification of SRPS equipment fire risk hazard sources: when classifying SRPS equipment fire risk hazard sources, environmental factors are considered, including the climate conditions, temperature, humidity, building structure, and dust in which the SRPS is located. The first type of hazard source is the root cause of SRPS fire, and the second type of hazard source and environmental factors are necessary conditions for fire accidents. First, a first-level risk factor mainly composed of the first and second types of hazard sources is constructed, and environmental factors are added to the first-level risk factors during operation. The first-level risk factors are analyzed layer by layer, and various types of hazard source factors that may cause SRPS equipment fire risks are subdivided and summarized into second-level risk factors;

[0016] The hazards are divided into the first category and the second category according to their degree of danger. The first category is defined as the hazard that will cause serious harm to the SRPS system or personnel safety; the second category is derived from the first category.

[0017] Preferably, the hazard source estimation and identification of SRPS equipment fire risk:

[0018] 1) Estimation and analysis of fire hazard sources of solar photovoltaic cell modules: TPT, EVA and junction box are all classified as combustibles. EVA is the most easily ignited part of the entire module. Compared with EVA, junction box and TPT are the second most easily ignited parts. There are two reasons for fire in solar photovoltaic power stations: one is spontaneous combustion caused by hot spot effect, and the other is the combustion of combustibles caused by arc sparks;

[0019] 2) Estimation and analysis of cable fire hazard sources: Cable fires are caused by overload, line aging and installation defects;

[0020] 3) Analysis of fire hazard sources of controllers and inverters: The combustible materials are the circuit boards and insulation layers where the electronic components are located. The causes of fire are overload, arc sparks, and short circuits.

[0021] 4) Estimation and analysis of transformer fire hazard sources: The flammable materials inside the transformer are its internal components and transformer oil. The transformer will cause explosion hazards when a fire occurs. Open flames must be isolated around it, and the equipment must not overheat. Fire prevention measures must be taken. At the same time, the transformer should be isolated from the system to prevent fires in other equipment in the system from affecting it and reduce the risk of explosion.

[0022] Preferably, the SRPS equipment fire risk assessment process: use specific symbols to express the relationship between the elements, and finally present an inverted logical cause and effect diagram. The basic analysis steps are:

[0023] Step 1: Determine the target object of fire analysis and determine the content and boundaries of the exploration target;

[0024] Step 2: Determine the top event. The top event must be clearly defined.

[0025] Step 3: Analyze the familiarity of the SRPS system. Not only should you be familiar with the performance of the SRPS system, but you should also be familiar with the workflow, environment, and operating procedures of the SRPS system.

[0026] Step 4: Investigate the causes of the top events. For the top events identified, investigate and analyze them one by one and finally determine the related causes.

[0027] Step 5: Construction of the accident tree, using logical methods to deduce the SRPS equipment fire, from the result to the cause, layer by layer analysis until the basic event is terminated, and finally determine the inverted tree diagram, that is, the accident tree diagram;

[0028] Step 6: Qualitative analysis: Based on the accident tree, qualitatively analyze the causes of these failures and distinguish the roles of the basic events involved;

[0029] Step 7: Quantitative analysis: Based on the establishment of the model and qualitative analysis, quantitative analysis is carried out from a quantitative perspective to process the artificial chaotic and imprecise experience and data, and to use analysis to quantify the chaos of each event;

[0030] Step 8: Develop safety countermeasures. According to the analysis results, identify hidden dangers and defects, make targeted improvements to the fire risks of SRPS equipment, and develop and implement safety control measures with clear objectives.

[0031] Preferably, the chaotic entropy of the fire risk factor of the SRPS equipment is: In the real number domain U, q is the chaotic entropy, which is approximately m, μ q (x) represents the membership function of q, and the membership function of fire risk chaos entropy is expressed as:

[0032]

[0033] Among them, m is the chaotic center of q, c+d is the chaotic interval of q, when c and d are 0, m is not the chaotic entropy, the larger c and d are, the more chaotic m is, and the chaotic entropy is q Represented by c, d, and m, it is expressed as q =(c,m,d);

[0034] 1) Calculation of fire risk chaos entropy

[0035] Assuming the fire risk chaos entropy q 1=(c1,m1,d1), q 2=(c2,m2,d2), then the addition between chaotic entropy Subtraction multiplication The definition is as follows:

[0036] 1) Fire risk chaos entropy Operation:

[0037]

[0038] 2) Fire risk chaos entropy Operation:

[0039]

[0040] 3) Fire risk chaos entropy Operation:

[0041]

[0042] 2) Chaos operator of fire risk accident tree

[0043] The logical AND gate and logical OR gate operators of the accident tree fire risk analysis are expressed as follows:

[0044]

[0045] In the formula, q i is the probability of event i, and the chaotic entropy is expanded to obtain the following formula:

[0046] Logical AND gate operator:

[0047] in:

[0048]

[0049] Logical OR gate operator:

[0050]

[0051] in:

[0052]

[0053] In the formula, c and d are selected based on experience and calculated data;

[0054] 3) Chaotic calculation of fire risk probability

[0055] For fire risks where the exact probability cannot be obtained, an assessment expert group of more than three people estimates the probability of the occurrence of the basic fire event, taking its mean m and standard deviation σ. Assuming that the probability follows a normal distribution, the probability that the true probability falls between [m-3σ, m+3σ] is 99.7%. Let c=d=3σ, where 3σ is the upper and lower limits of the probability fluctuation. Each probability can be expressed in the form of (3σ, m, 3σ). For discrete random variables, the mean m is the expectation E(x), which is calculated as follows:

[0056]

[0057] In the formula, x i is the probability value of the ith item,

[0058] Preferably, a fire risk factor assessment model for SRPS equipment is established:

[0059] 1) Determine the top event of fire risk: select the fire source existing in SRPS as the top event for analysis;

[0060] 2) Establish a primary accident tree: The fire sources of SRPS fire accidents include the following aspects: ① spontaneous combustion; ② ignition caused by arc sparks; ③ sparks generated by lightning; ④ fire sources caused by human and other factors; ②, ③, and ④ are classified into the ignition part, and the relationship between the three is logical or;

[0061] 3) Construct a tree diagram of spontaneous combustion accidents: Spontaneous combustion of photovoltaic modules is caused by hot spot effect and module aging. The causes of hot spot effect are: first, the quality problem of photovoltaic modules themselves, and second, shadow blocking; the causes of spontaneous combustion of cables and other electrical equipment are overheating and equipment aging. The causes of overheating are: first, overload, and second, the quality problem of the equipment itself;

[0062] 4) Construct a fault accident tree diagram: The fire caused by the fault arc is caused by the DC arc spark. The DC arc is caused by multiple reasons such as the breakage of each connection interface, the virtual connection, the quality of the welding interface, and the insulation damage causing the short circuit;

[0063] 5) Establish the fire source accident tree of SRPS: summarize the logic tree diagram model of fire source accidents existing in SRPS.

[0064] Preferably, qualitative assessment of fire risk of SRPS equipment:

[0065] 1. Simplification of SRPS fire source accident tree diagram: Solve the minimum cut set of the top event SRPS with fire source, and expand it from top to bottom, level by level, and finally obtain the required group pairs. Through the logical operation analysis of the entire accident tree, the fire accident tree is simplified as follows:

[0066] T=X1+X2+X3+X4+X5+X6+X7+X8+X9+X10+X11+X12+X13+X14*X15 Formula 13

[0067] X1 indicates lightning sparks, X2 indicates ignition caused by human factors or other factors, X3 indicates aging of components, X4 indicates aging of equipment, X5 indicates grounding fault, X6 indicates substandard quality of PV components, X7 indicates overload, X8 indicates substandard quality of equipment itself, X9 indicates reverse connection or short circuit of lines, X10 indicates insulation fault, X11 indicates substandard welding of interfaces, X12 indicates interface corrosion, X13 indicates line breakage or virtual connection caused by external force or deadweight, X14 indicates shadow obstruction, and X15 indicates maintenance failure;

[0068] 2. Solve the minimum cut set: Boolean operation simplification analysis results in 14 expansions, all of which are minimum cut sets. Each occurrence will lead to the inevitable occurrence of the top event. These combinations are: {X1}, {X2}, {X3}, {X4}, {X5}, {X6}, {X7}, {X8}, {X9}, {X10}, {X11}, {X12}, {X13}, {X14, X15};

[0069] According to the duality of the minimum path set and the minimum cut set, there are two minimum path sets in total, namely {X1, X2, X3, X4, X5, X6, X7, X8, X9, X10, X11, X12, X13, X14} and {X1, X2, X3, X4, X5, X6, X7, X8, X9, X10, X11, X12, X13, X15}.

[0070] 3. Structural importance analysis: According to the structural importance calculation criteria and the obtained minimum cut set, the structural importance of the minimum cut set of the fault tree is obtained as follows:

[0071] I(X1)=I(X2)=I(X3)=I(X4)=I(X5)=I(X6)=I(X7)=I(X8)=I(X9)=I(X10)=I(X11)=I(X12)=I(X13) Equation 14

[0072] I(X14)=I(X15) Formula 15

[0073] Through the approximate judgment equation of structural importance, the structural importance coefficient of the above basic fire events is calculated as follows:

[0074]

[0075] According to the above approximate calculation results, the structural importance of each basic event of the top fire risk event is ranked as follows:

[0076] I(X1)=I(X2)=1(X3)=1(X4)=1(X5)=I(X6)=(X7)=I(X8)

[0077] = I(X9)=1(X10)=I(X11)=I(X12)=I(X13)>1(X14)=I(X15) Equation 17

[0078] Complete a qualitative assessment of the fire risk of SRPS equipment.

[0079] Preferably, the quantitative evaluation of fire risk factors of SRPS equipment:

[0080] 1- Obtaining the chaotic probability of basic events: Using the expert scoring method to obtain expert scores, and then performing chaotic processing on the obtained expert scores to obtain the chaotic probability of each basic event;

[0081] 1) Construct an expert scoring table: The expert scoring table is anonymously distributed to experts in the industry, and contains a summary table of events that need to be scored. After obtaining the scoring table returned by the experts, the scoring table is summarized and analyzed, and the tables that are unqualified or cannot be used as references are eliminated. The qualified tables are then classified and analyzed to obtain the chaos entropy of the basic events, and finally the chaos probability of the basic events is obtained, and quantitative analysis is performed according to the chaos accident tree analysis;

[0082] When designing the scoring table, chaotic language values ​​are used to replace traditional scores. A set of language values ​​including {very low, low, lower, medium, higher, high, very high} is used to make chaotic judgments on the probability of an event.

[0083] 2) Obtaining chaotic entropy data: Use language values ​​to judge the probability of a fault event, convert the language set {very low, low, relatively low, medium, relatively high, high, very high} into an English set {VL, L, FL, M, FM, H, VH}, and use the chaotic entropy to approximate the language judgment value;

[0084] The linear ordered relationship of the language value is defined according to the center of gravity of the chaotic membership function: VL≤L≤FL≤M≤FH≤H≤VH. After obtaining the scoring table for calculation and analysis, the language description value is converted into a chaotic probability value.

[0085] 2- Chaotic probability analysis of top events: The chaotic probability of a fire source appearing in SRPS is calculated as follows:

[0086]

[0087] Substituting the chaos probability of the above basic events and solving them step by step, we get q T =(0.603, 0.738, 0.838), the probability of a fire source appearing in SRPS is 0.738, and the fluctuation range is (0.603, 0.838). The possibility of a fire source appearing in SRPS is very high, and it should be taken seriously and relevant control measures should be formulated;

[0088] 3- Analysis of the probability importance of basic events: For basic events without precise probability, the importance of basic events scored by experts is equal to their central value. The probability importance of each basic event is sorted, and the chaos importance of each basic event is as follows:

[0089] F'(X1)=0.063, F'(X2)=0.001, F'(X3)=0.092, F'(X4)=0.045,

[0090] F'(X5)=0.073, F'(X6)=0.080, F'(X7)=0.050, F(X8)=0.040,

[0091] F'(X9)=0.157, F'(X10)=0.127, F'(X11)=0.160, F'(X12)=0.147,

[0092] F'(X13)=0.183, F'(X14)=0.200, F'(X15)=0.177,

[0093] The probability importance of each basic event is ranked as follows:

[0094] F'(X14)>F'(X13)>F'(X15)>F'(X11)>F'(X9)>F'(X12)>F'(X10)> F'(X3)>F'(X6)>F'(X5)>F'(X1)>F'(X7)>F'(X4)>F'(X8)>F'(X2),

[0095] The main factors that lead to fire sources in SRPS are shadows from photovoltaic cell modules, line breaks or false connections caused by external forces or deadweight, uncleaned surfaces of photovoltaic cell modules, unqualified interface welding, reverse or short circuited lines, interface corrosion, insulation failure, aging of photovoltaic cell modules, and unqualified quality of photovoltaic modules. Corresponding measures should be formulated to strengthen control efforts; grounding faults, lightning sparks, overloads, aging of equipment, unqualified quality of equipment itself, human and other factors are the second most important factors; the control of these factors should be carried out according to actual needs in combination with engineering practice requirements to reduce the occurrence of fire sources in SRPS;

[0096] As for the fire risk of building photovoltaic power generation equipment, its danger sources are concentrated in two places. The first is the hot spot effect, which corresponds to the solar photovoltaic cell modules; the second is the arc spark, which corresponds to the various connection interfaces between equipment, especially photovoltaic solar cell modules. When preventing the fire risk of building roof photovoltaic power generation equipment, the quality, installation quality, operation and maintenance of solar photovoltaic cell modules need to be paid special attention, followed by the connection of the interfaces between various devices.

[0097] Preferably, the control of SRPS equipment fire risk: introduce a risk control system to systematically control and manage the dangerous source elements of SRPS fire accidents, propose fire risk control measures for different stages after SRPS operation according to the order of SRPS system establishment, transfer the risk of SRPS equipment fire risk factors that cannot be eliminated through insurance, and minimize the harm caused by fire risks;

[0098] Full-cycle hazard source control: Based on the time sequence of SRPS establishment, its life cycle is divided into planning and design stage, transportation and installation stage, and operation and maintenance stage. According to the above full-cycle risk prevention and control system, the results of hazard source identification are classified and analyzed according to their time range, and targeted fault hazard source control is carried out in different life cycles to classify the risk results.

[0099] Preferably, the SRPS equipment fire risk full cycle control system:

[0100] 1. Planning and design stage: including planning and site selection, system design, and equipment selection;

[0101] 1) Site planning: Do a good job of investigation. First, avoid shadows when installing solar photovoltaic panels or during system operation, and eliminate fire hazards caused by this reason; second, ensure the reasonable orientation of solar photovoltaic cell components; finally, make a reasonable layout of solar cell components, avoid excessive concentration of solar panels, and leave sufficient flame-retardant space and fire escape routes;

[0102] 2) System design: First, plan the system reasonably to determine the maximum power generation after the system is in operation, that is, determine the maximum load capacity of the system, then design the system equipment and equipment installation, and finally design reasonable fire control measures in combination with the surrounding environment and the characteristics of the building where the system is located; the design of electrical equipment in the system must fully consider the heat dissipation requirements and its own load requirements during the operation of the equipment to prevent overload and overheating;

[0103] 3) Equipment selection: Power generation companies need to establish a white list of solar cell module suppliers, regulate the access of photovoltaic module companies, establish a quality access system, and regulate product quality; combustible materials in cables and systems should be selected with good flame retardant properties to delay the occurrence of combustion and provide maximum time for the discovery of fire hazards; the most likely cause of fire in electrical equipment in the system is overheating of equipment caused by overload or substandard equipment quality. The solar radiation in the area where the SRPS is located in a year should be reasonably planned during the design period to eliminate the problem of insufficient load caused by design reasons. At the same time, the quality of equipment should be strictly controlled to ensure that the system does not have fires caused by overheating due to equipment quality reasons;

[0104] 2. Transportation and installation stage

[0105] 1) Quality control of equipment transportation: The fire quality control at this stage is to prevent the occurrence of hidden cracks in the battery strings of photovoltaic battery modules. The control measures at this stage are safe transportation control and battery module collision prevention;

[0106] 2) Quality control during the equipment installation phase: First, the quality training and assessment of the installation workers; second, the control of installation quality. The control of installation quality starts from the control of equipment installation, among which the quality control of photovoltaic cell assembly installation is the most important; second, the control of the connection quality between each device;

[0107] 3) System debugging and operation: Hazard source prevention and control focuses on the detection of photovoltaic module power generation operation status, and the load and electrical performance test of each device in the system operation;

[0108] 3. Operation and maintenance phase: Start with the development of safety checklists, skills training for maintenance personnel, fire emergency drills, and the establishment of fire prevention and control rules and regulations and organizational structures.

[0109] Compared with the prior art, the innovations and advantages of this application are:

[0110] (1) This application analyzes and clarifies the reasons for the frequent fire failures of rooftop photovoltaic equipment, with the aim of using scientific and effective methods to identify the hazardous source elements of fire risk accidents, conduct risk assessment, and propose targeted risk control methods. Combined with the characteristics of rooftop photovoltaic power generation systems, based on the characteristics of fire accidents, the hazard sources are identified to provide a foundation and support for subsequent risk control, and to provide scientific guidance for reducing the losses caused by fire accidents in rooftop photovoltaic power generation systems. By identifying the hazardous source elements of fire risk accidents in building rooftop photovoltaic equipment, risk control measures are proposed, and the content of management and control of fire risk accidents in building rooftop photovoltaic equipment is improved. According to the theoretical system of risk management and control, combined with the characteristics of system structure and engineering practice, the focus is on identifying and evaluating the hazardous source elements that cause fire risks, and the control measures are analyzed and studied, and targeted safety operation checklists and ways to transfer risks using insurance are proposed. A set of efficient and complete fire risk assessment system for rooftop photovoltaic power generation systems has been established, which has greatly reduced the fire risk and losses of SRPS equipment, and is conducive to the large-scale promotion and application of solar rooftop photovoltaic power generation systems.

[0111] (2) This application identifies the hazard sources of fires in rooftop photovoltaic power generation systems, proposes corresponding control methods and methods to reduce losses and transfer risks, and finally applies them to engineering practice. The hazard pre-analysis method is used to complete the identification of SRPS equipment fire risks; in view of the fact that basic data is lacking, chaos entropy is introduced to construct chaos accident tree evaluation analysis to complete the quantitative analysis of SRPS equipment fire risks. After completing the hazard source identification, targeted risk control measures are analyzed, a safety checklist for fire risk control of building rooftop photovoltaic power generation equipment is established, and a risk control system is established. The innovative points of this application also include: first, after analyzing the characteristics of building rooftop photovoltaic power generation system equipment, a pre-hazard analysis method is constructed, and the identification of fire risk sources of building rooftop photovoltaic power generation equipment is completed, providing certain practical guidance for building rooftop photovoltaic fire protection. In view of the fact that it is impossible to accurately obtain probability data when conducting quantitative analysis of fire risk sources of building rooftop photovoltaic power generation equipment, chaos entropy is introduced to combine it with accident tree evaluation analysis, successfully completing the quantitative analysis of SRPS equipment fire risks, and obtaining quantitative analysis results. Second, the identified hazards were classified according to the design, installation, and operation stages, and the hazards at different stages were analyzed using the system life cycle method, and the analysis and control methods were proposed to build a risk control system. A safety checklist was designed for the hazards during operation, providing a solution for the routine prevention and control of hazards at this stage.

[0112] (3) This application identifies, analyzes and evaluates the hazard sources of fire risk accidents of building rooftop photovoltaic power generation equipment, builds a system life cycle risk control system, analyzes the rooftop photovoltaic power generation system and its fire risk, and qualitatively identifies the hazard sources of fire risk of building rooftop photovoltaic power generation equipment based on hazard source pre-analysis, and uses chaos accident tree evaluation analysis to perform quantitative analysis and evaluation. Based on the inability to obtain effective probabilities for each basic event of SRPS equipment fire risk, a chaos accident tree evaluation analysis is constructed to solve the problem that fire risk probability data is difficult to obtain, complete the quantitative analysis and evaluation of SRPS equipment fire risk hazard sources, and determine the probability importance of each basic event; for the identified hazard sources, the hazard sources are classified according to the system formation time, and targeted risk control methods are established for different hazard sources in different periods. At the same time, for the built and operated SRPS, a SRPS equipment fire risk safety checklist is established. Through the components and application of the safety checklist, the fire risk is eliminated in daily maintenance. Finally, for fire accidents that cannot be eliminated, the risk is transferred through insurance to eliminate or reduce the losses caused by fire accidents. It plays a very important role in eliminating or reducing the dangerous hidden dangers of rooftop photovoltaic power generation systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0113] Figure 1 This is a schematic diagram of the classification of fire risk hazards of SRPS equipment.

[0114] Figure 2 It is a schematic diagram of fire hazard estimation and analysis of solar photovoltaic cell modules.

[0115] Figure 3 It is a flow chart of establishing a real-time water level relationship model using the upstream water level and the water level at the previous moment.

[0116] Figure 4 It is a schematic diagram of the symbols used in the accident tree and their meanings.

[0117] Figure 5 This is a schematic diagram of the primary accident tree of the SRPS fire accident.

[0118] Figure 6 This is a schematic diagram of the accident tree of SRPS spontaneous combustion.

[0119] Figure 7 It is a schematic diagram of the logic tree diagram model of fire source accidents existing in SRPS.

[0120] Figure 8 It is a schematic diagram of the approximate chaotic entropy of the language value set {VL,L,FL,M,FM,H,VH}.

[0121] Fig. 9 It is a schematic diagram of fire prevention and control measures during the operation and maintenance phase.

[0122] Fig.10 It is a classification diagram of the fire risk hazard source identification results of SRPS equipment.

[0123] Fig.11 It is the framework diagram of the full-cycle control system of fire risk of SRPS equipment. DETAILED DESCRIPTION

[0124] The following, in conjunction with the accompanying drawings, further describes the technical solution of the fire risk assessment method for the solar roof photovoltaic power generation system provided by the present application, so that those skilled in the art can better understand the present application and implement it.

[0125] Photovoltaic systems convert sunlight energy directly into electrical energy, and have the advantages of being clean, harmless, and inexhaustible. As an application form of photovoltaic power generation systems, rooftop photovoltaic power generation systems (SRPS) have gradually entered people's field of vision with the maturity of technology and demand, and are showing a trend of continuous expansion. However, the continuous fire accidents in rooftop photovoltaic power generation systems have brought hidden dangers to people's lives and property safety.

[0126] This application identifies, analyzes and evaluates the hazard sources of fire risk accidents of photovoltaic power generation equipment on the roof of a building, and builds a system life cycle risk control system based on its characteristics. First, the roof photovoltaic power generation system and its fire risk are analyzed, and the hazard sources of fire risk of the roof photovoltaic power generation equipment are qualitatively identified based on the pre-analysis of the hazard sources. The chaotic accident tree evaluation analysis is used for quantitative analysis and evaluation, and a chaotic accident tree evaluation analysis is constructed to solve the problem that fire risk probability data is difficult to obtain, complete the quantitative analysis and evaluation of the SRPS equipment fire risk hazard sources, and determine the probability importance of each basic event; for the identified hazard sources, the hazard sources are classified according to the system formation time, and targeted risk control methods are established for different hazard sources in different periods. At the same time, for the built and operated SRPS, a SRPS equipment fire risk safety checklist is established. Through the components and applications of the safety checklist, the fire risk is eliminated in daily maintenance. Finally, for fire accidents that cannot be eliminated, the risk is transferred through insurance to eliminate or reduce the losses caused by fire accidents;

[0127] 1) Identification of fire risk factors of SRPS equipment: First, classify the fire risk sources of SRPS equipment, and build a hazard level classification based on severity and frequency according to the characteristics of the fire risk sources of SRPS equipment. Then, analyze the fire risk of the SRPS system from the perspective of different equipment. Finally, use the hazard source estimation method to conduct a qualitative analysis of its fire accidents. Based on the identification of the fire risk sources of SRPS equipment, qualitatively determine the cause of the fire and its risk level;

[0128] 2) SRPS equipment fire risk assessment: Chaos accident tree evaluation analysis is used to quantitatively analyze and evaluate the fire risk sources of SRPS equipment. When constructing the chaos accident tree analysis, the ignition source of the SRPS equipment fire risk is first determined as the top event, and then the accident tree logic analysis diagram is gradually constructed. Qualitative analysis is performed according to the accident tree. After quantitative analysis of the SRPS equipment fire risk, an expert scoring table is constructed. Through questionnaire surveys, the language chaos value is converted into a probability value to obtain chaos probability data. Based on the chaos entropy, the probability data of each basic event is obtained, and quantitative analysis and evaluation are completed to determine the probability importance of the system fire risk source;

[0129] 3) Control of fire risks of SRPS equipment: From the perspective of the system life cycle, the hazard sources are classified according to the planning and design, transportation and installation, operation and maintenance time periods, and corresponding risk control measures are formulated. For the fire risk hazard sources during the operation period with the longest system life, a safety checklist is formulated to provide a plan for the routine prevention and control of hazard sources during this period.

[0130] 1. Identification of fire risk factors of SRPS equipment

[0131] (I) Classification of fire risk sources of SRPS equipment

[0132] When classifying the hazardous sources of fire risk for SRPS equipment, environmental factors are considered, including the climate conditions, temperature, humidity, building structure, and dust in which the SRPS is located. The first type of hazardous source is the root cause of SRPS fire, and the second type of hazardous source and environmental factors are necessary conditions for fire accidents. First, a first-level risk factor mainly composed of the first and second types of hazardous sources is constructed, and environmental factors are added to the first-level risk factors during operation. The first-level risk factors are analyzed layer by layer, and the various types of hazardous source factors that may cause SRPS equipment fire risks are subdivided and summarized into second-level risk factors.

[0133] The hazards are divided into the first category and the second category according to their degree of danger. The first category is defined as the hazard that will cause serious harm to the SRPS system or personnel safety; the second category is derived from the first category.

[0134] Combined with the above classification of the two types of risk sources, the classification of SRPS equipment fire risk sources is as follows: Figure 1 shown.

[0135] (II) Estimation and identification of hazardous sources of fire risk for SRPS equipment

[0136] 1. Estimation and analysis of fire hazard sources of solar photovoltaic cell modules

[0137] In the composition of solar photovoltaic cell modules, TPT, EVA and junction box are all classified as combustibles. EVA is the most ignitable part of the entire module, and the junction box and TPT are the second most ignitable parts compared to EVA.

[0138] There are two reasons for fire in solar photovoltaic power plants: one is spontaneous combustion caused by the hot spot effect, and the other is the combustion of combustibles caused by electric arc sparks.

[0139] Based on the causes, consequences, and process elements of solar photovoltaic cell fires, the hazard source estimation analysis is as follows: Figure 2 shown.

[0140] 2. Cable fire hazard source estimation and analysis

[0141] Cable fires are caused by overload, line aging and installation defects. The hazard source estimation analysis for cable fires is as follows: Figure 3 shown.

[0142] 3. Analysis of fire hazard sources in controllers and inverters

[0143] This type of equipment is composed of a control circuit board, a frame and internal connecting cable devices. The combustible materials are the circuit board and insulation layer where the electronic components are located. The cause of the fire is overload, arc spark, and short circuit. This is an estimate and analysis of the dangerous sources of fire in electrical equipment.

[0144] 4. Estimation and analysis of transformer fire hazard sources

[0145] The flammable materials inside the transformer are its internal components and transformer oil. The transformer will cause an explosion hazard when a fire occurs. Open flames must be isolated around it, and the equipment must not overheat. Fire prevention measures must be taken. At the same time, the transformer should be isolated from the system to prevent fires in other equipment in the system from affecting it and reduce the risk of explosion.

[0146] 2. Fire risk assessment of SRPS equipment

[0147] Accident tree evaluation and analysis is used to quantitatively evaluate the identified hazardous sources. For hazardous sources that lack data, chaos accident tree evaluation and analysis is constructed to solve the problem of being unable to make quantitative evaluation due to lack of data.

[0148] (I) SRPS equipment fire risk assessment process

[0149] Specific symbols are used to express the relationship between the elements, and finally an inverted logical cause and effect diagram is presented. The symbols used in the accident tree and their meanings are as follows: Figure 4 The basic analysis steps are:

[0150] Step 1: Determine the target object of fire analysis and determine the content and boundaries of the exploration target;

[0151] Step 2: Determine the top event. The top event must be clearly defined.

[0152] Step 3: Analyze the familiarity of the SRPS system. Not only should you be familiar with the performance of the SRPS system, but you should also be familiar with the workflow, environment, and operating procedures of the SRPS system.

[0153] Step 4: Investigate the causes of the top events. For the top events identified, investigate and analyze them one by one and finally determine the related causes.

[0154] Step 5: Construction of the accident tree, using logical methods to deduce the SRPS equipment fire, from the result to the cause, layer by layer analysis until the basic event is terminated, and finally determine the inverted tree diagram, that is, the accident tree diagram;

[0155] Step 6: Qualitative analysis: Based on the accident tree, qualitatively analyze the causes of these failures and distinguish the roles of the basic events involved;

[0156] Step 7: Quantitative analysis: Based on the establishment of the model and qualitative analysis, quantitative analysis is carried out from a quantitative perspective to process the artificial chaotic and imprecise experience and data, and to use analysis to quantify the chaos of each event;

[0157] Step 8: Develop safety countermeasures. According to the analysis results, identify hidden dangers and defects, make targeted improvements to the fire risks of SRPS equipment, and develop and implement safety control measures with clear objectives.

[0158] (II) Chaos entropy of fire risk factors of SRPS equipment

[0159] In the domain of real numbers U, q is the chaos entropy, which is approximately m, μ q (x) indicates q The membership function of fire risk chaos entropy is expressed as:

[0160]

[0161] Among them, m is the chaotic center of q, c+d is the chaotic interval of q, when c and d are 0, m is not the chaotic entropy, the larger the c and d are, the more chaotic m is. The chaotic entropy q is represented by c, d, and m, expressed as q=(c, m, d).

[0162] 1. Calculation of fire risk chaos entropy

[0163] Assuming the fire risk chaos entropy q 1=(c1,m1,d1), q 2=(c2,m2,d2), then the addition between chaotic entropy Subtraction multiplication The definition is as follows:

[0164] 1) Fire risk chaos entropy Operation:

[0165]

[0166] 2) Fire risk chaos entropy Operation:

[0167]

[0168] 3) Fire risk chaos entropy Operation:

[0169]

[0170] 2. Chaos operator of fire risk accident tree

[0171] The logical AND gate and logical OR gate operators of the accident tree fire risk analysis are expressed as follows:

[0172]

[0173] In the formula, q i is the probability of event i, and the chaotic entropy is expanded to obtain the following formula:

[0174] Logical AND gate operator: in:

[0175]

[0176] Logical OR gate operator:

[0177]

[0178] in:

[0179]

[0180] Where c and d are selected based on experience and calculation data.

[0181] 3. Chaotic calculation of fire risk probability

[0182] For fire risks where the exact probability cannot be obtained, an assessment expert group of more than three people estimates the probability of the occurrence of the basic fire event, taking its mean m and standard deviation σ. Assuming that the probability follows a normal distribution, the probability that the true probability falls between [m-3σ, m+3σ] is 99.7%. Let c=d=3σ, where 3σ is the upper and lower limits of the probability fluctuation. Each probability can be expressed in the form of (3σ, m, 3σ). For discrete random variables, the mean m is the expectation E(x), which is calculated as follows:

[0183]

[0184] In the formula, x i is the probability value of the ith item,

[0185] (III) Establishing a fire risk factor assessment model for SRPS equipment

[0186] 1. Identify top fire risk events

[0187] Among the three elements that cause SRPS fires, namely combustibles, oxidants and fire sources, the fire source can be discovered and controlled. As long as the fire source is controlled, eliminated or reduced, the occurrence of SRPS fire accidents can be eliminated. The fire source of SRPS is selected as the top event for analysis.

[0188] 2. Establish a primary accident tree

[0189] The fire sources of SRPS fire accidents are as follows: ① spontaneous combustion; ② ignition by arc sparks from faults; ③ sparks from lightning strikes; ④ fire sources caused by human factors and other factors;

[0190] Among the above-mentioned fire causes, ②, ③, and ④ are classified into the ignition part, and there is a logical OR relationship between the three. There is a logical OR relationship between spontaneous combustion and ignition. The primary accident tree of the SRPS fire accident source is constructed as follows: Figure 5 shown.

[0191] 3. Construct a tree diagram of spontaneous combustion accidents

[0192] The spontaneous combustion of photovoltaic modules is caused by the hot spot effect and module aging. The causes of the hot spot effect are: first, the quality of the photovoltaic modules themselves, and second, shadows. The causes of spontaneous combustion of cables and other electrical equipment are overheating and equipment aging. The causes of overheating are: first, overload, and second, the quality of the equipment itself. The accident tree diagram of SRPS spontaneous combustion is as follows Figure 6 shown.

[0193] 4. Construct a fault accident tree diagram

[0194] Fires caused by fault arcs are caused by DC arc sparks. DC arcs are caused by multiple reasons, such as breakage of various connection interfaces, loose connection, welding interface quality, and insulation damage resulting in short circuits.

[0195] 5. Establish a fire source accident tree for SRPS

[0196] Summarize Figure 7 The logical tree diagram model of the fire source accident existing in SRPS is shown. The events in the accident tree are represented by codes: T represents the fire source existing in RFPV, M1 represents spontaneous combustion, M2 represents ignition, M3 represents spontaneous combustion of photovoltaic cell components, M4 represents spontaneous combustion of other equipment in the system, M5 represents fault arc, M6 represents hot spot effect, M7 represents overheating, M8 represents short circuit fault, M9 represents connection fault, M10 represents shadow shielding, X1 represents lightning spark, X2 represents ignition caused by human and other factors, X3 represents component aging, X4 represents equipment aging, X5 represents grounding fault, X6 represents unqualified quality of photovoltaic components, X7 represents overload, X8 represents unqualified quality of equipment itself, X9 represents reverse connection or short circuit of line, X10 represents insulation fault, X11 represents unqualified interface welding, X12 represents interface corrosion, X13 represents line break or virtual connection caused by external force or dead weight, X14 represents shadow shielding, and X15 represents maintenance and cleaning.

[0197] (IV) Qualitative assessment of fire risk of SRPS equipment

[0198] 1. Simplified SRPS fire source accident tree diagram

[0199] Solve the minimum cut set of the fire source in the top event SRPS, and expand it from top to bottom, level by level, and finally obtain the required group pairs. Through the logical operation analysis of the entire accident tree, the fire accident tree is simplified as follows:

[0200] T=X1+X2+X3+X4+X5+X6+X7+X8+X9+X10+X11+X12+X13+X14*X15 Formula 13

[0201] 2. Solve the minimum cut set

[0202] The simplified analysis of Boolean operations yields 14 expansions, all of which are minimal cut sets. Each occurrence will lead to the inevitable occurrence of the top event. These combinations are: {X1}, {X2}, {X3}, {X4}, {X5}, {X6}, {X7}, {X8}, {X9}, {X10}, {X11}, {X12}, {X13}, {X14, X15};

[0203] According to the duality of the minimum path set and the minimum cut set, there are two minimum path sets in total, namely {X1, X2, X3, X4, X5, X6, X7, X8, X9, X10, X11, X12, X13, X14} and {X1, X2, X3, X4, X5, X6, X7, X8, X9, X10, X11, X12, X13, X15}.

[0204] 3. Structural importance analysis

[0205] According to the calculation criteria of structural importance and the obtained minimum cut set, the structural importance of the minimum cut set of the fault tree is obtained as follows:

[0206] I(X1)=I(X2)=I(X3)=I(X4)=I(X5)=I(X6)=I(X7)=I(X8)=I(X9)=I(X10)=I(X11)=I(X12)=I(X13) Equation 14

[0207] I(X14)=I(X15) Formula 15

[0208] Through the approximate judgment equation of structural importance, the structural importance coefficient of the above basic fire events is calculated as follows:

[0209]

[0210] According to the above approximate calculation results, the structural importance of each basic event of the top fire risk event is ranked as follows:

[0211] I(X1)=I(X2)=1(X3)=1(X4)=1(X5)=I(X6)=(X7)=I(X8)

[0212] = I(X9)=1(X10)=I(X11)=I(X12)=I(X13)>1(X14)=I(X15) Equation 17

[0213] Complete a qualitative assessment of the fire risk of SRPS equipment.

[0214] 4. Qualitative conclusions

[0215] Through the accident tree analysis, there are 14 minimum cut sets and 2 minimum path sets for the top events. The top event, i.e., SRPS, is very likely to have a fire source, that is, the risk of fire accidents in the rooftop photovoltaic power generation system is very high. Without considering the probability of each basic event or assuming that the probability of all basic events is the same, the weak links that lead to the top events are found. In the absence of the probability of each basic event, the relative danger of each basic event to the top event is qualitatively identified, and the order of importance of the prevention and control measures that can be taken is determined. The qualitative analysis conclusions are as follows:

[0216] (1) The existence of combustibles in the SRPS system is inevitable and cannot be eliminated. In view of this situation, first of all, the combustibles involved in the SRPS must be guaranteed. In the design or equipment selection, materials with good flame retardancy should be given priority to buy time for the discovery and elimination of fires. Secondly, for combustibles such as transformer oil, isolation work should be done to prevent the entry of fire sources, and monitoring and fire fighting work should be done well. Finally, the equipment needs to be maintained regularly, and aging or damaged equipment should be replaced in time to eliminate fire hazards.

[0217] (2) The fire sources in SRPS were analyzed by minimum cut set, minimum path set and structural importance. It was found that the characteristics of the SRPS system itself caused the basic events that led to the existence of fire sources to have multiple logical relationships. The importance of the devices could not be effectively identified during the qualitative analysis. In order to establish a targeted risk prevention and control system in the future, it is necessary to conduct a more in-depth quantitative analysis.

[0218] (V) Quantitative evaluation of fire risk factors of SRPS equipment

[0219] 1. Obtaining the Chaotic Probability of Basic Events

[0220] The expert scoring method is used to obtain expert scores, and then the obtained expert scores are subjected to chaotic processing to obtain the chaotic probability of each basic event.

[0221] 1) Construct an expert scoring table

[0222] The expert scoring sheet is anonymously distributed to experts in the industry, which contains a summary form of the events that need to be scored. After obtaining the scoring sheets returned by the experts, the scoring sheets are summarized and analyzed, and the unqualified forms or forms that cannot be used as references are eliminated. The qualified forms are then classified and analyzed to obtain the chaos entropy of the basic events, and finally the chaos probability of the basic events, and quantitative analysis is performed according to the chaos accident tree analysis.

[0223] When designing the scoring table, chaotic language values ​​are used instead of traditional scores. A set of language values ​​including {very low, low, lower, medium, higher, high, very high} is used to make chaotic judgments on the probability of an event occurring.

[0224] 2) Obtaining Chaos Entropy Data

[0225] The language value is used to judge the probability of the occurrence of a fault event. The language set {very low, low, relatively low, medium, relatively high, high, very high} is converted into an English set {VL, L, FL, M, FM, H, VH}. The language judgment value is approximated by the chaotic entropy. The approximate chaotic entropy of the above language value set {VL, L, FL, M, FM, H, VH} is as follows: Figure 8 .

[0226] The linear ordered relationship of the language value is defined according to the center of gravity of the chaotic membership function: VL≤L≤FL≤M≤FH≤H≤VH. After obtaining the scoring table for calculation and analysis, the language description value is converted into a chaotic probability value.

[0227] 2. Analysis of Chaos Probability of Top Events

[0228] The chaotic probability of fire source appearing in SRPS is calculated as follows:

[0229]

[0230] Substituting the chaos probability of the above basic events and solving them step by step, we get q T =(0.603, 0.738, 0.838), the probability of a fire source appearing in SRPS is 0.738, and the fluctuation range is (0.603, 0.838). The possibility of a fire source appearing in SRPS is very high, and it should be taken seriously, and relevant control measures should be formulated.

[0231] 3. Analysis of the probability importance of basic events

[0232] For basic events without precise probabilities, the importance of the basic events scored by experts is equal to their central values. The probability importance of each basic event is sorted, and the chaos importance of each basic event is as follows:

[0233] F'(X1)=0.063, F'(X2)=0.001, F'(X3)=0.092, F'(X4)=0.045,

[0234] F'(X5)=0.073, F'(X6)=0.080, F'(X7)=0.050, F(X8)=0.040,

[0235] F'(X9)=0.157, F'(X10)=0.127, F'(X11)=0.160, F'(X12)=0.147,

[0236] F'(X13)=0.183, F'(X14)=0.200, F'(X15)=0.177,

[0237] The probability importance of each basic event is ranked as follows:

[0238] F'(X14)>F'(X13)>F'(X15)>F'(X11)>F'(X9)>F'(X12)>F'(X10)> F'(X3)>F'(X6)>F'(X5)>F'(X1)>F'(X7)>F'(X4)>F'(X8)>F'(X2),

[0239] The main factors that lead to fire sources in SRPS are shadows from photovoltaic cell modules, line breaks or loose connections caused by external forces or their own weight, uncleaned surfaces of photovoltaic cell modules, unqualified interface welding, reverse or short-circuited lines, interface corrosion, insulation failure, aging of photovoltaic cell modules, and unqualified quality of photovoltaic modules. Corresponding measures should be formulated to increase control efforts; grounding faults, lightning sparks, overloads, aging of equipment, unqualified quality of equipment itself, and human and other factors are the next most important factors. The control of these factors should be carried out according to actual needs in combination with engineering practice requirements to reduce the occurrence of fire sources in SRPS.

[0240] As for the fire risk of building photovoltaic power generation equipment, its danger sources are concentrated in two places. The first is the hot spot effect, which corresponds to the solar photovoltaic cell modules; the second is the arc spark, which corresponds to the various connection interfaces between equipment, especially photovoltaic solar cell modules. When preventing the fire risk of building roof photovoltaic power generation equipment, the quality, installation quality, operation and maintenance of solar photovoltaic cell modules need to be paid special attention, followed by the connection of the interfaces between various devices.

[0241] 5.7 Chapter Summary

[0242] Chaos accident tree evaluation and analysis is used to quantitatively analyze and evaluate the fire risk hazard sources of SRPS equipment. When constructing the chaos accident tree analysis, the ignition source of the fire risk of SRPS equipment is first determined as the top event, and then the accident tree logic analysis diagram is gradually constructed. Qualitative analysis is performed according to the accident tree. After quantitative analysis of the fire risk of SRPS equipment, an expert scoring table is constructed. Through questionnaire surveys, the language chaos value is converted into a probability value to obtain chaotic probability data. Based on the chaos entropy, the probability data of each basic event is obtained, and quantitative analysis and evaluation are completed to determine the probability importance of the system fire risk hazard source.

[0243] 3. Control of Fire Risk of SRPS Equipment

[0244] A risk control system is introduced to systematically control and manage the hazardous source elements of SRPS fire accidents. According to the order of SRPS system establishment, fire risk control measures for different stages after SRPS operation are proposed. The risk of SRPS equipment fire risk causes that cannot be eliminated is transferred through insurance, minimizing the harm caused by fire risks.

[0245] (I) Full-cycle hazard source control

[0246] According to the time sequence of SRPS establishment, its life cycle is divided into planning and design stage, transportation and installation stage, and operation and maintenance stage. According to the above full-cycle risk prevention and control system, the results of hazard source identification are classified and analyzed according to their time range, and targeted fault hazard source control is carried out in different life cycles. The risk classification results are as follows: Fig.10 shown.

[0247] (II) SRPS equipment fire risk full cycle control system

[0248] 1. Planning and design stage

[0249] It includes three aspects: planning and site selection, system design, and equipment selection;

[0250] 1) Site planning: Do a good job of investigation. First, avoid shadows when installing solar photovoltaic panels or during system operation, and eliminate fire hazards caused by this reason; secondly, ensure the reasonable orientation of solar photovoltaic cell components; finally, make a reasonable layout of solar cell components, avoid excessive concentration of solar panels, and leave sufficient flame-retardant space and fire escape routes.

[0251] 2) System design: First, plan the system reasonably to determine the maximum power generation after the system is put into operation, that is, determine the maximum load capacity of the system, and then design the system equipment and equipment installation. Finally, it is necessary to design reasonable fire control measures based on the surrounding environment and the characteristics of the building where the system is located. The design of electrical equipment in the system must fully consider the heat dissipation requirements and its own load requirements during the operation of the equipment to prevent overload and overheating.

[0252] 3) Equipment selection: Power generation companies need to establish a white list of solar cell module suppliers, standardize the access of photovoltaic module companies, establish a quality access system, and standardize product quality; combustible materials in cables and systems should be selected with good flame retardant properties to delay the occurrence of combustion and provide maximum time for the discovery of fire hazards; the most likely cause of fire in electrical equipment in the system is overheating of equipment caused by overload or substandard equipment quality. During the design period, the solar radiation in the area where the SRPS is located in a year should be reasonably planned to eliminate the problem of insufficient load caused by design reasons. At the same time, the quality of equipment should be strictly controlled to ensure that the system does not have fires caused by overheating due to equipment quality reasons.

[0253] 2. Transportation and installation stage

[0254] 1) Quality control of equipment transportation: The fire quality control at this stage is to prevent the occurrence of hidden cracks in the battery strings in the photovoltaic battery modules. The control measures at this stage are safe transportation control and battery module collision prevention.

[0255] 2) Quality control during the equipment installation phase: First, the quality training and assessment of the installation workers; second, the control of installation quality. The control of installation quality starts from the control of equipment installation, among which the quality control of photovoltaic cell module installation is the most important; the second is the control of the connection quality between each device.

[0256] 3) System debugging and operation: Hazard source prevention and control focuses on the detection of the power generation and operation status of photovoltaic modules (including single modules and multiple modules combined), and the load-bearing and electrical performance testing of each device in the system operation.

[0257] 3. Operation and maintenance phase

[0258] Fire prevention and control measures in the operation and maintenance phase include the development of safety checklists, skills training for maintenance personnel, fire emergency drills, establishment of fire prevention and control rules and regulations, and organizational structure. Fig. 9 shown.

[0259] (III) SRPS Equipment Fire Risk Transfer Insurance Scheme

[0260] The existence and occurrence of fire risk are absolute, while control is relative. For risks caused by reasons beyond human control, such as accidents, it is necessary to use risk transfer to transfer these risks, to eliminate losses caused by such accidents as much as possible, and to use insurance solutions to transfer risks.

[0261] Insurance for SRPS equipment fire risk is essentially a form of wealth loss preservation. Fire insurance offsets or transfers the insured's risk damage by compensating the insured's bid for losses;

[0262] When insuring SRPS, fire risk is included in the basic property insurance. When a fire accident occurs, the losses caused by the fire to the photovoltaic power generation system and its ancillary buildings can be transferred or reduced to a certain extent;

[0263] Insurance is an effective way to transfer the fire risk of SRPS equipment. It requires insurance companies to cooperate with photovoltaic power generation companies in research, improve the basic data and practical cases of relevant insurance products, and provide support and guarantee for the in-depth growth of the photovoltaic conversion industry.

[0264] Establish a full-cycle control system for SRPS equipment fire risks such as Fig.11 shown.

Claims

1. A fire risk assessment method for a solar roof photovoltaic power generation system, characterized in that: Identify, analyze and evaluate the hazard sources of fire risk accidents of photovoltaic power generation equipment on the roof of buildings, and build a system life cycle risk control system based on its characteristics. First, analyze the roof photovoltaic power generation system and its fire risks, and qualitatively identify the hazard sources of fire risks of roof photovoltaic power generation equipment based on the pre-analysis of hazard sources. Use chaos accident tree evaluation analysis to conduct quantitative analysis and evaluation, and build chaos accident tree evaluation analysis to solve the problem that fire risk probability data is difficult to obtain, complete the quantitative analysis and evaluation of SRPS equipment fire risk hazard sources, and determine the probability importance of each basic event; for the identified hazard sources, classify the hazard sources according to the system formation time, and establish targeted risk control methods for different hazard sources in different periods. At the same time, for the built and operated SRPS, establish a SRPS equipment fire risk safety checklist, and eliminate the fire risk in daily maintenance through the components and applications of the safety checklist. Finally, for fire accidents that cannot be eliminated, transfer risks through insurance to eliminate or reduce the losses caused by fire accidents; 1) Identification of fire risk factors of SRPS equipment: First, classify the fire risk sources of SRPS equipment, and build a hazard level classification based on severity and frequency according to the characteristics of the fire risk sources of SRPS equipment. Then, analyze the fire risk of the SRPS system from the perspective of different equipment. Finally, use the hazard source estimation method to conduct a qualitative analysis of its fire accidents. Based on the identification of the fire risk sources of SRPS equipment, qualitatively determine the cause of the fire and its risk level; 2) SRPS equipment fire risk assessment: Chaos accident tree evaluation analysis is used to quantitatively analyze and evaluate the fire risk sources of SRPS equipment. When constructing the chaos accident tree analysis, the ignition source of the SRPS equipment fire risk is first determined as the top event, and then the accident tree logic analysis diagram is gradually constructed. Qualitative analysis is performed according to the accident tree. After quantitative analysis of the SRPS equipment fire risk, an expert scoring table is constructed. Through questionnaire surveys, the language chaos value is converted into a probability value to obtain chaos probability data. Based on the chaos entropy, the probability data of each basic event is obtained, and quantitative analysis and evaluation are completed to determine the probability importance of the system fire risk source; 3) Control of fire risks of SRPS equipment: From the perspective of the system life cycle, the hazard sources are classified according to the planning and design, transportation and installation, operation and maintenance time periods, and corresponding risk control measures are formulated. For the fire risk hazard sources during the operation period with the longest system life, a safety checklist is formulated to provide a plan for the routine prevention and control of hazard sources during this period.

2. The fire risk assessment method for solar roof photovoltaic power generation system according to claim 1 is characterized in that: Classification of SRPS equipment fire risk sources: When classifying the fire risk sources of SRPS equipment, environmental factors are considered, including the climate conditions, temperature, humidity, building structure, and dust in which the SRPS is located. The first type of hazard source is the root cause of SRPS fires, and the second type of hazard source and environmental factors are necessary conditions for fire accidents. First, a first-level risk factor based on the first and second types of hazard sources is constructed, and environmental factors are added to the first-level risk factors during operation. The first-level risk factors are analyzed layer by layer, and various types of hazard source factors that may cause SRPS equipment fire risks are subdivided and summarized into second-level risk factors; The hazards are divided into the first category and the second category according to their degree of danger. The first category is defined as the hazard that will cause serious harm to the SRPS system or personnel safety; the second category is derived from the first category.

3. The fire risk assessment method for solar roof photovoltaic power generation system according to claim 1 is characterized in that: Estimation and identification of hazard sources of fire risk in SRPS equipment: 1) Estimation and analysis of fire hazard sources of solar photovoltaic cell modules: TPT, EVA and junction box are all classified as combustibles. EVA is the most easily ignited part of the entire module. Compared with EVA, junction box and TPT are the second most easily ignited parts. There are two reasons for fire in solar photovoltaic power stations: one is spontaneous combustion caused by hot spot effect, and the other is the combustion of combustibles caused by arc sparks; 2) Estimation and analysis of cable fire hazard sources: Cable fires are caused by overload, line aging and installation defects; 3) Analysis of fire hazard sources of controllers and inverters: The combustibles are the circuit boards and insulation layers where the electronic components are located. The causes of fire are overload, arc sparks, and short circuits. 4) Estimation and analysis of transformer fire hazard sources: The flammable materials inside the transformer are its internal components and transformer oil. The transformer will cause explosion hazards when a fire occurs. Open flames must be isolated around it, and the equipment must not overheat. Fire prevention measures must be taken. At the same time, the transformer should be isolated from the system to prevent fires in other equipment in the system from affecting it and reduce the risk of explosion.

4. The fire risk assessment method for solar roof photovoltaic power generation system according to claim 1 is characterized in that: SRPS equipment fire risk assessment process: Use specific symbols to express the relationship between the elements, and finally present an inverted logical cause and effect diagram. The basic analysis steps are: Step 1: Determine the target object of fire analysis and determine the content and boundaries of the exploration target; Step 2: Determine the top event. The top event must be clearly defined. Step 3: Analyze the familiarity of the SRPS system. Not only should you be familiar with the performance of the SRPS system, but you should also be familiar with the workflow, environment, and operating procedures of the SRPS system. Step 4: Investigate the causes of the top events. For the top events identified, investigate and analyze them one by one and finally determine the related causes. Step 5: Construction of the accident tree, using logical methods to deduce the SRPS equipment fire, from the result to the cause, layer by layer analysis until the basic event is terminated, and finally determine the inverted tree diagram, that is, the accident tree diagram; Step 6: Qualitative analysis: Based on the accident tree, qualitatively analyze the causes of these failures and distinguish the roles of the basic events involved; Step 7: Quantitative analysis: Based on the establishment of the model and qualitative analysis, quantitative analysis is carried out from a quantitative perspective to process the artificial chaotic and imprecise experience and data, and to use analysis to quantify the chaos of each event; Step 8: Develop safety countermeasures. According to the analysis results, identify hidden dangers and defects, make targeted improvements to the fire risks of SRPS equipment, and develop and implement safety control measures with clear objectives.

5. The fire risk assessment method for solar roof photovoltaic power generation system according to claim 1 is characterized in that: Chaos entropy of fire risk factors of SRPS equipment: In the real number domain U, q is the chaos entropy, which is approximately m, μ q (x) represents the membership function of q, and the membership function of fire risk chaos entropy is expressed as: Among them, m is q The chaotic center of q The chaotic interval, when c and d are 0, m is not the chaotic entropy. The larger c and d are, the more chaotic m is. q Represented by c, d, and m, it is expressed as q =(c,m,d); 1) Calculation of fire risk chaos entropy Assuming the fire risk chaos entropy q 1=(c1,m1,d1), q 2=(c2,m2,d2), then the addition between chaotic entropy Subtraction multiplication The definition is as follows: 1) Fire risk chaos entropy Operation: 2) Fire risk chaos entropy Operation: 3) Fire risk chaos entropy Operation: 2) Chaos operator of fire risk accident tree The logical AND gate and logical OR gate operators of the accident tree fire risk analysis are expressed as follows: In the formula, q i is the probability of event i, and the chaotic entropy is expanded to obtain the following formula: Logical AND gate operator: in: Logical OR gate operator: in: In the formula, c and d are selected based on experience and calculated data; 3) Chaotic calculation of fire risk probability For fire risks where the exact probability cannot be obtained, an assessment expert group of more than three people estimates the probability of the occurrence of the basic fire event, taking its mean m and standard deviation σ. Assuming that the probability follows a normal distribution, the probability that the true probability falls between [m-3σ, m+3σ] is 99.7%. Let c=d=3σ, where 3σ is the upper and lower limits of the probability fluctuation. Each probability can be expressed in the form of (3σ, m, 3σ). For discrete random variables, the mean m is the expectation E(x), which is calculated as follows: In the formula, xi is the probability value of the i-th item, (i=1,2,3,…,n).

6. The fire risk assessment method for solar roof photovoltaic power generation system according to claim 1 is characterized in that: Establishing the fire risk factor assessment model for SRPS equipment: 1) Determine the top event of fire risk: select the fire source existing in SRPS as the top event for analysis; 2) Establish a primary accident tree: The fire sources of SRPS fire accidents include the following aspects: ① spontaneous combustion; ② ignition caused by arc sparks; ③ sparks generated by lightning; ④ fire sources caused by human and other factors; ②, ③, and ④ are classified into the ignition part, and the relationship between the three is logical or; 3) Construct a tree diagram of spontaneous combustion accidents: Spontaneous combustion of photovoltaic modules is caused by hot spot effect and module aging. The causes of hot spot effect are: first, the quality problem of photovoltaic modules themselves, and second, shadow blocking; the causes of spontaneous combustion of cables and other electrical equipment are overheating and equipment aging. The causes of overheating are: first, overload, and second, the quality problem of the equipment itself; 4) Construct a fault accident tree diagram: The fire caused by the fault arc is caused by the DC arc spark. The DC arc is caused by multiple reasons such as the breakage of each connection interface, the virtual connection, the quality of the welding interface, and the insulation damage causing the short circuit; 5) Establish the fire source accident tree of SRPS: summarize the logic tree diagram model of fire source accidents existing in SRPS.

7. The fire risk assessment method for solar roof photovoltaic power generation system according to claim 1 is characterized in that: Qualitative assessment of fire risk of SRPS equipment:

1. Simplification of SRPS fire source accident tree diagram: Solve the minimum cut set of the top event SRPS with fire source, and expand it from top to bottom, level by level, and finally obtain the required group pairs. Through the logical operation analysis of the entire accident tree, the fire accident tree is simplified as follows: T=X1+X2+X3+X4+X5+X6+X7+X8+X9+X10+X11+X12+X13+X14*X15 Formula 13 X1 indicates lightning sparks, X2 indicates ignition caused by human factors or other factors, X3 indicates aging of components, X4 indicates aging of equipment, X5 indicates grounding fault, X6 indicates substandard quality of photovoltaic components, X7 indicates overload, X8 indicates substandard quality of equipment itself, X9 indicates reverse connection or short circuit of lines, X10 indicates insulation fault, X11 indicates substandard welding of interfaces, X12 indicates interface corrosion, X13 indicates line breakage or virtual connection caused by external force or deadweight, X14 indicates shadow obstruction, and X15 indicates maintenance failure; 2. Solve the minimum cut set: Boolean operation simplification analysis results in 14 expansions, all of which are minimum cut sets. Each occurrence will lead to the inevitable occurrence of the top event. These combinations are: {X1}, {X2}, {X3}, {X4}, {X5}, {X6}, {X7}, {X8}, {X9}, {X10}, {X11}, {X12}, {X13}, {X14, X15}; According to the duality of the minimum path set and the minimum cut set, there are two minimum path sets in total, namely {X1, X2, X3, X4, X5, X6, X7, X8, X9, X10, X11, X12, X13, X14} and {X1, X2, X3, X4, X5, X6, X7, X8, X9, X10, X11, X12, X13, X15}; 3. Structural importance analysis: According to the structural importance calculation criteria and the obtained minimum cut set, the structural importance of the minimum cut set of the fault tree is obtained as follows: I(X1)=I(X2)=I(X3)=I(X4)=I(X5)=I(X6)=I(X7) =I(X8)=I(X9)=I(X10)=I(X11)=I(X12)=I(X13) Equation 14 I(X14)=I(X15) Formula 15 Through the approximate judgment equation of structural importance, the structural importance coefficient of the above basic fire events is calculated as follows: According to the above approximate calculation results, the structural importance of each basic event of the top fire risk event is ranked as follows: I(X1)=I(X2)=1(X3)=1(X4)=1(X5)=I(X6)=(X7)=I(X8) =I(X9)=1(X10)=I(X11)=I(X12)=I(X13)>1(X14)=I(X15) Equation 17 Complete a qualitative assessment of the fire risk of SRPS equipment.

8. The fire risk assessment method for solar roof photovoltaic power generation system according to claim 1 is characterized in that: Quantitative evaluation of fire risk factors of SRPS equipment: 1- Obtaining the chaotic probability of basic events: Using the expert scoring method to obtain expert scores, and then performing chaotic processing on the obtained expert scores to obtain the chaotic probability of each basic event; 1) Construct an expert scoring table: The expert scoring table is anonymously distributed to experts in the industry, and contains a summary table of events that need to be scored. After obtaining the scoring table returned by the experts, the scoring table is summarized and analyzed, and the unqualified tables or tables that cannot be used as references are eliminated. The qualified tables are then classified and analyzed to obtain the chaos entropy of the basic events, and finally the chaos probability of the basic events is obtained, and quantitative analysis is performed according to the chaos accident tree analysis; When designing the scoring table, chaotic language values ​​are used to replace traditional scores. A set of language values ​​including {very low, low, lower, medium, higher, high, very high} is used to make chaotic judgments on the probability of an event. 2) Obtaining chaotic entropy data: Use language values ​​to judge the probability of a fault event, convert the language set {very low, low, relatively low, medium, relatively high, high, very high} into an English set {VL, L, FL, M, FM, H, VH}, and use the chaotic entropy to approximate the language judgment value; The linear ordered relationship of the language value is defined according to the center of gravity of the chaotic membership function: VL≤L≤FL≤M≤FH≤H≤VH. After obtaining the scoring table for calculation and analysis, the language description value is converted into a chaotic probability value. 2- Chaotic probability analysis of top events: The chaotic probability of a fire source appearing in SRPS is calculated as follows: Substituting the chaos probability of the above basic events and solving them step by step, we get q T =(0.603, 0.738, 0.838), the probability of a fire source appearing in SRPS is 0.738, and the fluctuation range is (0.603, 0.838). The possibility of a fire source appearing in SRPS is very high, and it should be taken seriously and relevant control measures should be formulated; 3- Analysis of the probability importance of basic events: For basic events without precise probability, the importance of basic events scored by experts is equal to their central value. The probability importance of each basic event is sorted, and the chaos importance of each basic event is as follows: F'(X1)=0.063, F'(X2)=0.001, F'(X3)=0.092, F'(X4)=0.045, F'(X5)=0.073, F'(X6)=0.080, F'(X7)=0.050, F(X8)=0.040, F'(X9)=0.157, F'(X10)=0.127, F'(X11)=0.160, F'(X12)=0.147, F'(X13)=0.183, F'(X14)=0.200, F'(X15)=0.177, The probability importance of each basic event is ranked as follows: F'(X14)>F'(X13)>F'(X15)>F'(X11)>F'(X9)>F'(X12)>F'(X10)> F'(X3)>F'(X6)>F'(X5)>F'(X1)>F'(X7)>F'(X4)>F'(X8)>F'(X2), The main factors that lead to fire sources in SRPS are shadows from photovoltaic cell modules, line breaks or false connections caused by external forces or deadweight, uncleaned surfaces of photovoltaic cell modules, unqualified interface welding, reverse or short circuited lines, interface corrosion, insulation failure, aging of photovoltaic cell modules, and unqualified quality of photovoltaic modules. Corresponding measures should be formulated to strengthen control efforts; grounding faults, lightning sparks, overloads, aging of equipment, unqualified quality of equipment itself, human and other factors are the second most important factors; the control of these factors should be carried out according to actual needs in combination with engineering practice requirements to reduce the occurrence of fire sources in SRPS; As for the fire risk of building photovoltaic power generation equipment, its danger sources are concentrated in two places. The first is the hot spot effect, which corresponds to the solar photovoltaic cell modules; the second is the arc spark, which corresponds to the various connection interfaces between equipment, especially photovoltaic solar cell modules. When preventing the fire risk of building roof photovoltaic power generation equipment, the quality, installation quality, operation and maintenance of solar photovoltaic cell modules need to be paid special attention, followed by the connection of the interfaces between various devices.

9. The fire risk assessment method for solar roof photovoltaic power generation system according to claim 1, characterized in that: Control of SRPS equipment fire risk: Introduce a risk control system to systematically control and manage the hazardous source elements of SRPS fire accidents. According to the order of SRPS system establishment, propose fire risk control measures for different stages after SRPS operation. The fire risk factors of SRPS equipment that cannot be eliminated will be transferred through insurance to minimize the damage caused by fire risks. Full-cycle hazard source control: Based on the time sequence of SRPS establishment, its life cycle is divided into planning and design stage, transportation and installation stage, and operation and maintenance stage. According to the above full-cycle risk prevention and control system, the results of hazard source identification are classified and analyzed according to their time range, and targeted fault hazard source control is carried out in different life cycles to classify the risk results.

10. The fire risk assessment method for solar roof photovoltaic power generation system according to claim 1, characterized in that: SRPS equipment fire risk full cycle control system:

1. Planning and design stage: including planning and site selection, system design, and equipment selection; 1) Site planning: Do a good job of investigation. First, avoid shadows when installing solar photovoltaic panels or during system operation, and eliminate fire hazards caused by this reason; second, ensure the reasonable orientation of solar photovoltaic cell components; finally, make a reasonable layout of solar cell components, avoid excessive concentration of solar panels, and leave sufficient flame-retardant space and fire escape routes; 2) System design: First, plan the system reasonably to determine the maximum power generation after the system is in operation, that is, determine the maximum load capacity of the system, then design the system equipment and equipment installation, and finally design reasonable fire control measures in combination with the surrounding environment and the characteristics of the building where the system is located; the design of electrical equipment in the system must fully consider the heat dissipation requirements and its own load requirements during the operation of the equipment to prevent overload and overheating; 3) Equipment selection: Power generation companies need to establish a white list of solar cell module suppliers, regulate the access of photovoltaic module companies, establish a quality access system, and regulate product quality; combustible materials in cables and systems should be selected with good flame retardant properties to delay the occurrence of combustion and provide maximum time for the discovery of fire hazards; the most likely cause of fire in electrical equipment in the system is overheating of equipment caused by overload or substandard equipment quality. The solar radiation in the area where the SRPS is located in a year should be reasonably planned during the design period to eliminate the problem of insufficient load caused by design reasons. At the same time, the quality of equipment should be strictly controlled to ensure that the system does not have fires caused by overheating due to equipment quality reasons; 2. Transportation and installation stage 1) Quality control of equipment transportation: The fire quality control at this stage is to prevent the occurrence of hidden cracks in the battery strings of photovoltaic battery modules. The control measures at this stage are safe transportation control and battery module collision prevention; 2) Quality control during the equipment installation phase: First, the quality training and assessment of the installation workers; second, the control of installation quality. The control of installation quality starts from the control of equipment installation, among which the quality control of photovoltaic cell assembly installation is the most important; second, the control of the connection quality between each device; 3) System debugging and operation: Hazard source prevention and control focuses on the detection of photovoltaic module power generation operation status, and the load and electrical performance test of each device in the system operation; 3. Operation and maintenance phase: Start with the development of safety checklists, skills training for maintenance personnel, fire emergency drills, and the establishment of fire prevention and control rules and regulations and organizational structures.

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