A method for profiling low-voltage grid-connected photovoltaic system operation and related device

Abstract

The present application discloses a method for operating a low-voltage grid-connected photovoltaic system and a related device, the method comprising: constructing a membership function based on operating data of a reference low-voltage photovoltaic panel; calculating the membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to each operating state based on the membership function and several groups of operating data of the low-voltage photovoltaic panel to be evaluated, the operating state including normal, potential fault and fault; determining the operating state of each group of operating data of the low-voltage photovoltaic panel to be evaluated according to the membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to each operating state; realizing low-voltage photovoltaic operating state evaluation, which helps to improve the safety of the low-voltage photovoltaic power generation system.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic systems, and in particular to a method for profiling the operation of a low-voltage grid-connected photovoltaic system and a related device thereof. Background Art

[0002] The photovoltaic industry, especially low-voltage photovoltaics, has developed rapidly in recent years. From a relatively small market size before, it has gradually occupied an important position today. Low-voltage photovoltaic power generation systems are installed in residential buildings. Their characteristics are power generation, grid connection, and use nearby, which effectively solves the problem of power loss during voltage boosting and long-distance transportation. Although such a system has a series of advantages such as proximity to users, low transmission costs, little impact on the power grid, and flexible site selection, its operating risks cannot be ignored. For example, since the system is usually connected to the public power grid for operation, how to ensure safe and stable grid-connected operation has become an important issue.

[0003] The quality of low-voltage photovoltaic operation directly affects the grid-connected power generation efficiency and the operation of photovoltaic systems. The existing low-voltage photovoltaic operation status assessment method is based on power generation. This method mainly evaluates the operation status of the power station by calculating the actual power generation of the photovoltaic power station and comparing it with the expected power generation. However, the accuracy is affected by many factors such as installation conditions and weather. Since low-voltage power stations are scattered and the installation conditions vary greatly, this assessment method needs to consider many factors, which makes the assessment difficult. Summary of the invention

[0004] The present application provides a low-voltage grid-connected photovoltaic system operation profiling method and related devices, which are used to implement low-voltage photovoltaic operation status evaluation to improve the safety of low-voltage photovoltaic power generation systems.

[0005] In view of this, the first aspect of the present application provides a method for profiling the operation of a low-voltage grid-connected photovoltaic system, comprising:

[0006] A membership function is constructed based on the operating data of a reference low-voltage photovoltaic panel;

[0007] Calculate the membership value of each group of operation data of the low-voltage photovoltaic panel to be evaluated belonging to each operation state based on the membership function and several groups of operation data of the low-voltage photovoltaic panel to be evaluated, wherein the operation state includes normal, potential fault and fault;

[0008] The operating state of each group of operating data of the low-voltage photovoltaic panel to be evaluated is determined according to the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated to each operating state.

[0009] Optionally, the membership function includes a normal membership function, a fault potential membership function and a fault membership function; and constructing the membership function includes:

[0010] Acquire multiple groups of operating data of a reference low-voltage photovoltaic panel, wherein the operating data includes a maximum power point voltage, a maximum power point current, an open circuit voltage, and a short circuit current;

[0011] Calculating the normalized maximum power point voltage, the normalized maximum power point current and the fill factor corresponding to each group of operating data of the reference low-voltage photovoltaic panel, and constructing a characteristic vector;

[0012] Clustering the feature vectors using a clustering algorithm to obtain cluster center values;

[0013] A normal membership function, a fault potential membership function and a fault membership function are respectively constructed according to the cluster center value.

[0014] Optionally, the calculating, based on the membership function and a plurality of groups of operating data of the low-voltage photovoltaic panel to be evaluated, a membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to each operating state comprises:

[0015] Calculate the normalized maximum power point voltage, normalized maximum power point current and fill factor corresponding to each set of operating data of the low-voltage photovoltaic panel to be evaluated;

[0016] Substituting the normalized maximum power point voltage, normalized maximum power point current and fill factor corresponding to each group of operating data of the low-voltage photovoltaic panel to be evaluated into the normal membership function, the fault hidden danger membership function and the fault membership function for calculation, respectively, to obtain three groups of initial membership values ​​belonging to normal, three groups of membership values ​​belonging to fault hidden danger and three groups of membership values ​​belonging to fault for each group of operating data of the low-voltage photovoltaic panel to be evaluated;

[0017] Based on preset weights, weighted summation is performed on three groups of initial membership values ​​of each group of operation data of the low-voltage photovoltaic panel to be evaluated belonging to normal, to obtain a membership value of each group of operation data of the low-voltage photovoltaic panel to be evaluated belonging to normal;

[0018] Based on preset weights, weighted summation is performed on three groups of initial membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to the fault hidden danger, so as to obtain the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to the fault hidden danger;

[0019] Based on preset weights, three groups of initial membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to the fault are weighted summed to obtain the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to the fault.

[0020] Optionally, the normal membership function is:

[0021]

[0022] The fault hidden danger membership function is:

[0023]

[0024] The fault membership function is:

[0025]

[0026] Wherein, g1(v,j), g1(i,j), g1(f,j) are respectively the normalized maximum power point voltage, normalized maximum power point current, and fill factor corresponding to the j-th group of operating data of the low-voltage photovoltaic panel to be evaluated, belonging to the normal initial membership values; g2(v,j), g2(i,j), g2(f,j) are respectively the normalized maximum power point voltage, normalized maximum power point current, and fill factor corresponding to the j-th group of operating data of the low-voltage photovoltaic panel to be evaluated, belonging to the initial membership values ​​of the fault hidden danger; g3(v,j), g3(i,j), g3(f,j) are respectively the normalized maximum power point voltage, normalized maximum power point current, and fill factor corresponding to the j-th group of operating data of the low-voltage photovoltaic panel to be evaluated, belonging to the initial membership values ​​of the fault; β vj , β ij , β fj are the normalized maximum power point voltage, normalized maximum power point current, and fill factor corresponding to the jth group of operating data of the low-voltage photovoltaic panel to be evaluated; f(α U )、f(α C )、f(α F ) is the cluster center value.

[0027] Optionally, determining the operating state of each group of operating data of the low-voltage photovoltaic panel to be evaluated according to the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated to each operating state includes:

[0028] Compare the sizes of the membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to normal, the membership values ​​belonging to potential faults, and the membership values ​​belonging to faults, and select the operating state corresponding to the maximum membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated as the operating state of each group of operating data.

[0029] Optionally, the calculation formula of the normalized maximum power point voltage is:

[0030]

[0031] In the formula, α U is the normalized maximum power point voltage, u m is the maximum power point voltage, n s is the number of PV modules in series of the reference low-voltage PV panel, uoc It is the short-circuit voltage of the photovoltaic module under standard test conditions.

[0032] Optionally, the calculation formula of the normalized maximum power point current is:

[0033]

[0034] In the formula, α C is the normalized maximum power point current, c m is the maximum power point current, n p is the number of PV modules in parallel of the reference low-voltage PV panel, c sc It is the short-circuit current of the photovoltaic module under standard test conditions.

[0035] Optionally, the calculation formula of the fill factor is:

[0036]

[0037] In the formula, α F is the filling factor, u m is the maximum power point voltage, u oc is the short-circuit voltage of the photovoltaic module under standard test conditions, c m is the maximum power point current, c sc It is the short-circuit current of the photovoltaic module under standard test conditions.

[0038] A second aspect of the present application provides a low-voltage grid-connected photovoltaic system operation portrait device, comprising:

[0039] A construction unit, for constructing a membership function based on operating data of a reference low-voltage photovoltaic panel;

[0040] A calculation unit, configured to calculate, based on the membership function and a plurality of groups of operation data of the low-voltage photovoltaic panel to be evaluated, a membership value of each group of operation data of the low-voltage photovoltaic panel to be evaluated belonging to each operation state, wherein the operation state includes normal, potential fault and failure;

[0041] The state evaluation unit is used to determine the operating state of each group of operating data of the low-voltage photovoltaic panel to be evaluated according to the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated to each operating state.

[0042] A third aspect of the present application provides a computer-readable storage medium, which is used to store program code. When the program code is executed by a processor, the low-voltage grid-connected photovoltaic system operation profiling method described in any one of the first aspects is implemented.

[0043] It can be seen from the above technical solutions that this application has the following advantages:

[0044] The present application provides a method for operating profiling a low-voltage grid-connected photovoltaic system, comprising: constructing a membership function based on operating data of a reference low-voltage photovoltaic panel; calculating the membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to each operating state based on the membership function and several groups of operating data of the low-voltage photovoltaic panel to be evaluated, the operating states including normal, potential faults and faults; determining the operating state of each group of operating data of the low-voltage photovoltaic panel to be evaluated according to the membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to each operating state.

[0045] In the present application, a membership function is constructed based on the operating data of a reference low-voltage photovoltaic panel, and the membership function is used to calculate the membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated and each operating state. The operating state of the low-voltage photovoltaic panel to be evaluated is determined through the membership values ​​of each group of operating data and each operating state, thereby realizing the evaluation of the low-voltage photovoltaic operating state. This is beneficial for on-site operation and maintenance personnel to formulate maintenance plans according to the operating state of the low-voltage photovoltaic panel, and helps to improve the safety of the low-voltage photovoltaic power generation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0047] Figure 1 A schematic flow chart of a method for profiling the operation of a low-voltage grid-connected photovoltaic system provided in an embodiment of the present application;

[0048] Figure 2 A structural schematic diagram of a low-voltage grid-connected photovoltaic system operation portrait device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0049] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0050] For easier understanding, see Figure 1 The embodiment of the present application provides a method for profiling the operation of a low-voltage grid-connected photovoltaic system, comprising:

[0051] Step 101: construct a membership function based on the operating data of a reference low-voltage photovoltaic panel.

[0052] In the embodiment of the present application, a membership function is constructed based on multiple groups of operating data of reference low-voltage photovoltaic panels, and the membership function includes a normal membership function, a fault hidden danger membership function and a fault membership function. The specific process of constructing the membership function includes:

[0053] Step 1010, obtaining multiple groups of operating data of a reference low-voltage photovoltaic panel, the operating data including maximum power point voltage, maximum power point current, open circuit voltage and short circuit current;

[0054] The maximum power point voltage U of the reference low-voltage photovoltaic panel can be obtained every preset time period m =[u m1 ,u m2 ,…,u mN ]、Maximum power point current C m =[c m1 ,c m2 ,…,c mN ]、Open circuit voltage U OC =[u oc1 ,u oc2 ,…,u ocN ] and the short-circuit current C SC =[c sc1 ,c sc2 ,…,c scN ], and get N groups of running data.

[0055] Step 1011, calculating the normalized maximum power point voltage, normalized maximum power point current and fill factor corresponding to each group of operating data of the reference low-voltage photovoltaic panel, and constructing a feature vector;

[0056] Calculating the normalized maximum power point voltage, the normalized maximum power point current and the fill factor according to the maximum power point voltage, the maximum power point current, the open circuit voltage and the short circuit current in each group of operating data of the reference low-voltage photovoltaic panel, and obtaining the normalized maximum power point voltage, the normalized maximum power point current and the fill factor of each group of operating data;

[0057] Among them, the calculation formula of the normalized maximum power point voltage is:

[0058]

[0059] In the formula, α U is the normalized maximum power point voltage, u m is the maximum power point voltage, n s is the number of PV modules in series of the reference low-voltage PV panel, u ocIt is the short-circuit voltage of the photovoltaic module under standard test conditions; the standard test conditions in the embodiment of the present application are preferably a light intensity of 1000W / m2 and an ambient temperature of 25°C.

[0060] The normalized maximum power point current is calculated as:

[0061]

[0062] In the formula, α C is the normalized maximum power point current, c m is the maximum power point current, n p is the number of PV modules in parallel of the reference low-voltage PV panel, c sc It is the short-circuit current of the photovoltaic module under standard test conditions;

[0063] The calculation formula for fill factor is:

[0064]

[0065] In the formula, α F is the filling factor.

[0066] The normalized maximum power point voltage α of each group of operating data in N groups of operating data is calculated by the above formula: Ui , Normalized maximum power point current α Ci and the filling factor α Fi After (i=1,2,...,N), establish the feature vector X, X=[α U ,α C ,α F ] T α U =[α U1 ,α U2 ,...,α UN ], α C =[α C1 ,α C2 ,...,α CN ], α F =[α F1 ,α F2 ,...,α FN ].

[0067] Step 1012: clustering the feature vectors using a clustering algorithm to obtain cluster center values;

[0068] Use clustering algorithm to cluster the feature vector X and get the cluster center value [α Uo ,α Co ,α Fo ].

[0069] Step 1013: constructing a normal membership function, a fault potential membership function and a fault membership function respectively according to the cluster center value;

[0070] According to the cluster center value, the normal membership function, fault hidden danger membership function and fault membership function are constructed respectively. The normal membership function is:

[0071]

[0072] The fault hidden danger membership function is:

[0073]

[0074] The fault membership function is:

[0075]

[0076] Wherein, g1(v,j), g1(i,j), g1(f,j) are respectively the normalized maximum power point voltage, normalized maximum power point current, and fill factor corresponding to the j-th group of operating data of the low-voltage photovoltaic panel to be evaluated, belonging to the normal initial membership values; g2(v,j), g2(i,j), g2(f,j) are respectively the normalized maximum power point voltage, normalized maximum power point current, and fill factor corresponding to the j-th group of operating data of the low-voltage photovoltaic panel to be evaluated, belonging to the initial membership values ​​of the fault hidden danger; g3(v,j), g3(i,j), g3(f,j) are respectively the normalized maximum power point voltage, normalized maximum power point current, and fill factor corresponding to the j-th group of operating data of the low-voltage photovoltaic panel to be evaluated, belonging to the initial membership values ​​of the fault; β vj , β ij , β fj are the normalized maximum power point voltage, normalized maximum power point current, and fill factor corresponding to the jth group of operating data of the low-voltage photovoltaic panel to be evaluated; f(α U )、f(α C )、f(α F ) is the cluster center value, that is, f(α U )=α Uo , f(α C )=α Co , f(α F )=α Fo .

[0077] Step 102: Calculate the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to each operating state based on the membership function and a plurality of groups of operating data of the low-voltage photovoltaic panel to be evaluated.

[0078] The maximum power point voltage, maximum power point current, open circuit voltage and short circuit current of the low voltage photovoltaic panel to be evaluated are collected at every preset time period to obtain several groups of operation data of the low voltage photovoltaic panel to be evaluated. Based on each group of operation data, the operation status of the low voltage photovoltaic panel in each time period can be evaluated. The operation status includes normal, potential fault and fault.

[0079] Specifically, the normalized maximum power point voltage, normalized maximum power point current and fill factor corresponding to each set of operating data of the low-voltage photovoltaic panel to be evaluated are calculated. The specific calculation process is similar to the calculation process of the normalized maximum power point voltage, normalized maximum power point current and fill factor corresponding to each set of operating data of the reference low-voltage photovoltaic panel, and will not be repeated here.

[0080] Substitute the normalized maximum power point voltage, normalized maximum power point current and fill factor corresponding to each group of operating data of the low-voltage photovoltaic panel to be evaluated into the normal membership function, the fault hidden danger membership function and the fault membership function for calculation, and obtain three groups of initial membership values ​​belonging to normal, three groups of membership values ​​belonging to fault hidden danger and three groups of membership values ​​belonging to fault for each group of operating data of the low-voltage photovoltaic panel to be evaluated;

[0081] Based on the preset weights, the three groups of initial membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated are weighted and summed to obtain the membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to normal; in the embodiment of the present application, the weights of the three groups of initial membership values ​​of each group of operating data belonging to normal are preferably set to 1 / 3. At this time, the membership value g of each group of operating data belonging to normal 1total The calculation formula is:

[0082]

[0083] Based on the preset weights, the three groups of initial membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to the fault hidden danger are weighted summed to obtain the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to the fault hidden danger; the membership value g of each group of operating data belonging to the fault hidden danger 2total The calculation formula is:

[0084]

[0085] Based on the preset weights, the three initial membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to the fault are weighted summed to obtain the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to the fault; the membership value g of each group of operating data belonging to the fault 3total The calculation formula is:

[0086]

[0087] Step 103 : determining the operating state of each group of operating data of the low-voltage photovoltaic panel to be evaluated according to the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated to each operating state.

[0088] In the embodiment of the present application, the operating state is divided into three levels, namely normal, potential faults and faults. The membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to normal, the membership values ​​of the potential faults and the membership values ​​of the faults are compared, and the operating state corresponding to the maximum membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated is selected as the operating state of each group of operating data. For example, if the membership value of the j-th group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to normal is greater than the membership value belonging to the potential faults and the membership value belonging to the faults, then the operating state of the j-th group of operating data of the low-voltage photovoltaic panel to be evaluated is determined to be normal, that is, the low-voltage photovoltaic panel to be evaluated is operating normally in the time period corresponding to the j-th group of operating data.

[0089] In the embodiments of the present application, in the present application, a membership function is constructed based on the operating data of a reference low-voltage photovoltaic panel, and the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to each operating state is calculated through the membership function. The operating state of the low-voltage photovoltaic panel to be evaluated is determined through the membership value of each group of operating data belonging to each operating state, thereby realizing the evaluation of the low-voltage photovoltaic operating state, which is beneficial for on-site operation and maintenance personnel to formulate maintenance plans according to the operating state of the low-voltage photovoltaic panel, and helps to improve the safety of the low-voltage photovoltaic power generation system.

[0090] The above is an embodiment of a method for profiling the operation of a low-voltage grid-connected photovoltaic system provided by the present application, and the following is an embodiment of a device for profiling the operation of a low-voltage grid-connected photovoltaic system provided by the present application.

[0091] Please refer to Figure 2 , a low-voltage grid-connected photovoltaic system operation portrait device provided in an embodiment of the present application includes:

[0092] A construction unit, for constructing a membership function based on operating data of a reference low-voltage photovoltaic panel;

[0093] A calculation unit, for calculating the membership value of each group of operation data of the low-voltage photovoltaic panel to be evaluated belonging to each operation state based on the membership function and a plurality of groups of operation data of the low-voltage photovoltaic panel to be evaluated, wherein the operation state includes normal, potential fault and fault;

[0094] The state evaluation unit is used to determine the operating state of each group of operating data of the low-voltage photovoltaic panel to be evaluated according to the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated to each operating state.

[0095] As a further improvement, the membership function includes a normal membership function, a fault potential membership function and a fault membership function; the construction unit is specifically used for:

[0096] Acquire multiple sets of operating data of a reference low-voltage photovoltaic panel, the operating data including maximum power point voltage, maximum power point current, open circuit voltage, and short circuit current;

[0097] Calculate the normalized maximum power point voltage, normalized maximum power point current and fill factor corresponding to each set of operating data of the reference low-voltage photovoltaic panel, and construct a feature vector;

[0098] Clustering algorithm is used to cluster the feature vectors and obtain the cluster center value;

[0099] According to the cluster center values, the normal membership function, fault hidden danger membership function and fault membership function are constructed respectively.

[0100] In an embodiment of the present application, a membership function is constructed based on the operating data of a reference low-voltage photovoltaic panel, and the membership function is used to calculate the membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated and each operating state. The operating state of the low-voltage photovoltaic panel to be evaluated is determined by the membership values ​​of each group of operating data and each operating state, thereby realizing the evaluation of the low-voltage photovoltaic operating state. This is beneficial for on-site operation and maintenance personnel to formulate maintenance plans according to the operating state of the low-voltage photovoltaic panel, and helps to improve the safety of the low-voltage photovoltaic power generation system.

[0101] An embodiment of the present application also provides a computer-readable storage medium, which is used to store program code. When the program code is executed by a processor, the low-voltage grid-connected photovoltaic system operation profiling method in the aforementioned method embodiment is implemented.

[0102] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0103] The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0104] It should be understood that in the present application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0105] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0106] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0107] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0108] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for executing all or part of the steps of the method described in each embodiment of the present application through a computer device (which can be a personal computer, a server, or a network device, etc.). The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (full name in English: Read-Only Memory, English abbreviation: ROM), random access memory (full name in English: Random Access Memory, English abbreviation: RAM), disk or optical disk and other media that can store program codes.

[0109] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for profiling the operation of a low-voltage grid-connected photovoltaic system, characterized in that: include: A membership function is constructed based on the operating data of a reference low-voltage photovoltaic panel; Calculate the membership value of each group of operation data of the low-voltage photovoltaic panel to be evaluated belonging to each operation state based on the membership function and several groups of operation data of the low-voltage photovoltaic panel to be evaluated, wherein the operation state includes normal, potential fault and fault; Determining the operating state of each group of operating data of the low-voltage photovoltaic panel to be evaluated according to the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to each operating state; The membership function includes a normal membership function, a fault hidden danger membership function and a fault membership function; The constructing of the membership function comprises: Acquire multiple groups of operating data of a reference low-voltage photovoltaic panel, wherein the operating data includes a maximum power point voltage, a maximum power point current, an open circuit voltage, and a short circuit current; Calculating the normalized maximum power point voltage, the normalized maximum power point current and the fill factor corresponding to each group of operating data of the reference low-voltage photovoltaic panel, and constructing a characteristic vector; Clustering the feature vectors using a clustering algorithm to obtain cluster center values; According to the cluster center value, a normal membership function, a fault hidden danger membership function and a fault membership function are respectively constructed; The normal membership function is: The fault hidden danger membership function is: The fault membership function is: Wherein, g1(v,j), g1(i,j), g1(f,j) are respectively the normalized maximum power point voltage, normalized maximum power point current, and fill factor corresponding to the j-th group of operating data of the low-voltage photovoltaic panel to be evaluated, belonging to the normal initial membership values; g2(v,j), g2(i,j), g2(f,j) are respectively the normalized maximum power point voltage, normalized maximum power point current, and fill factor corresponding to the j-th group of operating data of the low-voltage photovoltaic panel to be evaluated, belonging to the initial membership values ​​of the fault hidden danger; g3(v,j), g3(i,j), g3(f,j) are respectively the normalized maximum power point voltage, normalized maximum power point current, and fill factor corresponding to the j-th group of operating data of the low-voltage photovoltaic panel to be evaluated, belonging to the initial membership values ​​of the fault; β vj , β ij , β fj are the normalized maximum power point voltage, normalized maximum power point current, and fill factor corresponding to the jth group of operating data of the low-voltage photovoltaic panel to be evaluated; f(α U )、f(α C )、f(α F ) is the cluster center value.

2. The low-voltage grid-connected photovoltaic system operation portrait method according to claim 1, characterized in that: The calculating, based on the membership function and a plurality of groups of operating data of the low-voltage photovoltaic panel to be evaluated, the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to each operating state comprises: Calculate the normalized maximum power point voltage, normalized maximum power point current and fill factor corresponding to each set of operating data of the low-voltage photovoltaic panel to be evaluated; Substituting the normalized maximum power point voltage, normalized maximum power point current and fill factor corresponding to each group of operating data of the low-voltage photovoltaic panel to be evaluated into the normal membership function, the fault hidden danger membership function and the fault membership function for calculation, respectively, to obtain three groups of initial membership values ​​belonging to normal, three groups of membership values ​​belonging to fault hidden danger and three groups of membership values ​​belonging to fault for each group of operating data of the low-voltage photovoltaic panel to be evaluated; Based on preset weights, weighted summation is performed on three groups of initial membership values ​​of each group of operation data of the low-voltage photovoltaic panel to be evaluated belonging to normal, to obtain a membership value of each group of operation data of the low-voltage photovoltaic panel to be evaluated belonging to normal; Based on preset weights, weighted summation is performed on three groups of initial membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to the fault hidden danger, to obtain the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to the fault hidden danger; Based on preset weights, three groups of initial membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to the fault are weighted summed to obtain the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to the fault.

3. The low-voltage grid-connected photovoltaic system operation portrait method according to claim 1, characterized in that: The step of determining the operating state of each group of operating data of the low-voltage photovoltaic panel to be evaluated according to the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated to each operating state includes: Compare the sizes of the membership values ​​of each group of operating data of the low-voltage photovoltaic panel to be evaluated belonging to normal, the membership values ​​belonging to potential faults, and the membership values ​​belonging to faults, and select the operating state corresponding to the maximum membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated as the operating state of each group of operating data.

4. The low-voltage grid-connected photovoltaic system operation portrait method according to claim 1, characterized in that: The calculation formula of the normalized maximum power point voltage is: In the formula, α U is the normalized maximum power point voltage, u m is the maximum power point voltage, n s is the number of PV modules in series of the reference low-voltage PV panel, u oc It is the short-circuit voltage of the photovoltaic module under standard test conditions.

5. The low-voltage grid-connected photovoltaic system operation portrait method according to claim 1, characterized in that: The calculation formula of the normalized maximum power point current is: In the formula, α C is the normalized maximum power point current, c m is the maximum power point current, n p is the number of PV modules in parallel of the reference low-voltage PV panel, c sc It is the short-circuit current of the photovoltaic module under standard test conditions.

6. The low-voltage grid-connected photovoltaic system operation portrait method according to claim 1, characterized in that: The calculation formula of the fill factor is: In the formula, α F is the filling factor, u m is the maximum power point voltage, u oc is the short-circuit voltage of the photovoltaic module under standard test conditions, c m is the maximum power point current, c sc It is the short-circuit current of the photovoltaic module under standard test conditions.

7. A low-voltage grid-connected photovoltaic system operation image device, characterized in that: include: A construction unit, for constructing a membership function based on operating data of a reference low-voltage photovoltaic panel; A calculation unit, configured to calculate, based on the membership function and a plurality of groups of operation data of the low-voltage photovoltaic panel to be evaluated, a membership value of each group of operation data of the low-voltage photovoltaic panel to be evaluated belonging to each operation state, wherein the operation state includes normal, potential fault and failure; A state evaluation unit, used to determine the operating state of each group of operating data of the low-voltage photovoltaic panel to be evaluated according to the membership value of each group of operating data of the low-voltage photovoltaic panel to be evaluated to each operating state; The membership function includes a normal membership function, a fault hidden danger membership function and a fault membership function; The constructing of the membership function comprises: Acquire multiple groups of operating data of a reference low-voltage photovoltaic panel, wherein the operating data includes a maximum power point voltage, a maximum power point current, an open circuit voltage, and a short circuit current; Calculating the normalized maximum power point voltage, the normalized maximum power point current and the fill factor corresponding to each group of operating data of the reference low-voltage photovoltaic panel, and constructing a characteristic vector; Clustering the feature vectors using a clustering algorithm to obtain cluster center values; According to the cluster center value, a normal membership function, a fault hidden danger membership function and a fault membership function are respectively constructed; The normal membership function is: The fault hidden danger membership function is: The fault membership function is: Wherein, g1(v,j), g1(i,j), g1(f,j) are respectively the normalized maximum power point voltage, normalized maximum power point current, and fill factor corresponding to the j-th group of operating data of the low-voltage photovoltaic panel to be evaluated, belonging to the normal initial membership values; g2(v,j), g2(i,j), g2(f,j) are respectively the normalized maximum power point voltage, normalized maximum power point current, and fill factor corresponding to the j-th group of operating data of the low-voltage photovoltaic panel to be evaluated, belonging to the initial membership values ​​of the fault hidden danger; g3(v,j), g3(i,j), g3(f,j) are respectively the normalized maximum power point voltage, normalized maximum power point current, and fill factor corresponding to the j-th group of operating data of the low-voltage photovoltaic panel to be evaluated, belonging to the initial membership values ​​of the fault; β vj , β ij , β fj are the normalized maximum power point voltage, normalized maximum power point current, and fill factor corresponding to the jth group of operating data of the low-voltage photovoltaic panel to be evaluated; f(α U )、f(α C )、f(α F ) is the cluster center value.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium is used to store program codes, and when the program codes are executed by a processor, the low-voltage grid-connected photovoltaic system operation profiling method described in any one of claims 1-6 is implemented.

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