Detection methods and related products for abnormal string in photovoltaic power station

Abstract

The present invention provides a method for detecting abnormal strings in a photovoltaic power station and related products. The method for detecting abnormal strings in a photovoltaic power station includes: obtaining photovoltaic operation data measured by sensors in the photovoltaic power station; the sensors include current sensors for measuring current data of photovoltaic strings or string combinations and voltage sensors for measuring voltage data of photovoltaic strings or string combinations; searching for matching photovoltaic strings or matching string combinations with similar operation data characteristics from the photovoltaic power station; extracting photovoltaic operation data of each matching photovoltaic string or matching string combination during a preset peak illumination period as comparison data; comparing the comparison data of matching photovoltaic strings or matching string combinations, and determining abnormal photovoltaic strings or abnormal string combinations based on the comparison results. This solution improves the detection accuracy, the detection algorithm is efficient and simple, reduces the number of sensors and other equipment used, and reduces costs.

Description

Technical Field

[0001] The present invention relates to photovoltaic technology, and in particular to a method for detecting abnormality of strings in a photovoltaic power station and related products. Background Art

[0002] With the continuous consumption of fossil energy such as coal and oil and the increasing environmental problems, new energy power generation has become the main form of energy substitution and power supply in the world. As a clean and environmentally friendly new energy power generation method, solar power generation has been widely used in recent years, among which photovoltaic power generation has developed particularly rapidly.

[0003] During the operation of a photovoltaic power station, photovoltaic modules may experience various anomalies, such as performance degradation, hot spot effect, shading, etc. If these anomalies are not discovered and handled in time, they may cause module damage and affect the overall power generation efficiency of the power station. The operation and maintenance of traditional photovoltaic power stations often rely on manual inspections, which is not only inefficient, but also difficult to grasp the working status of each photovoltaic module in real time.

[0004] Photovoltaic power stations occupy a large area and are generally located in areas with harsh environments and sparse populations, which makes manual inspections more difficult. Therefore, the operation and maintenance of existing photovoltaic power stations is not only inefficient, but also requires a lot of manpower and material resources. Summary of the invention

[0005] One purpose of the present invention is to improve the operation and maintenance efficiency of a photovoltaic power station and reduce the manpower required for operation and maintenance.

[0006] A further object of the present invention is to improve the accuracy of string anomaly detection in a photovoltaic power station.

[0007] A further object of the present invention is to meet the needs of abnormal string detection in photovoltaic power plants under various working conditions.

[0008] Another further object of the present invention is to more easily identify different photovoltaic module failure types.

[0009] In particular, the present invention provides a method for detecting abnormality of a photovoltaic string in a photovoltaic power station, comprising:

[0010] Acquire photovoltaic operation data measured by sensors in the photovoltaic power station; the sensors include current sensors for measuring current data of photovoltaic strings or string combinations and voltage sensors for measuring voltage data of photovoltaic strings or string combinations;

[0011] Find matching PV strings or matching string combinations with similar operating data characteristics from PV power stations;

[0012] Extracting photovoltaic operation data of each matching photovoltaic string or matching string combination during a preset peak light period as comparison data;

[0013] The comparison data of the matching photovoltaic strings or the matching string combinations are compared, and the abnormal photovoltaic strings or the abnormal string combinations are determined according to the comparison results.

[0014] Optionally, the step of comparing the comparison data of the matching photovoltaic strings or the matching string combinations includes:

[0015] The sizes of the paired data were compared separately;

[0016] If the relative ratio of the comparison data of any photovoltaic string or string combination in the matching photovoltaic string or the matching string combination to the comparison data of other photovoltaic strings or string combinations is greater than a preset threshold, it is determined that an abnormal photovoltaic string or abnormal string combination occurs.

[0017] Optionally, the step of searching for a matching photovoltaic string or a matching string combination having similar operating data characteristics from a photovoltaic power station includes:

[0018] Obtain the string connection topology of the photovoltaic power station;

[0019] The photovoltaic strings or string combinations connected to the same inverter are determined according to the string connection topology as matching photovoltaic strings or matching string combinations.

[0020] Optionally, the step of searching for a matching photovoltaic string or a matching string combination having similar operating data characteristics from a photovoltaic power station includes:

[0021] Obtain the location of the photovoltaic strings of the photovoltaic power station and the surrounding terrain information;

[0022] Photovoltaic strings or string combinations that are located adjacently and have similar surrounding terrains are regarded as matching photovoltaic strings or matching string combinations.

[0023] Optionally, the step of searching for a matching photovoltaic string or a matching string combination having similar operating data characteristics from a photovoltaic power station includes:

[0024] Obtain historical operating data of each photovoltaic string and string combination in the photovoltaic power station during the peak sunshine period;

[0025] According to the historical operation data, PV strings and string combinations with similar operation data characteristic curves are matched as matching PV strings or matching string combinations.

[0026] Optionally, the step of comparing the comparison data of the matching photovoltaic strings or the matching string combinations includes:

[0027] Generate an output characteristic curve according to the comparison data of the matching photovoltaic string or the matching string combination, the output characteristic curve including: an output current-voltage characteristic curve and / or an output power-voltage characteristic curve;

[0028] Compare the output characteristic curves of matching PV strings or matching string combinations to determine whether there are significant differences in the output characteristic curves;

[0029] If there is a significant difference, it is determined that an abnormal PV string or abnormal string combination has occurred.

[0030] Optionally, the step of comparing the output characteristic curves of the matching photovoltaic strings or the matching string combinations includes:

[0031] Extract characteristic points of the output characteristic curve, including peak value, valley value and inflection point;

[0032] Calculate the distance between feature points respectively;

[0033] When the sum of the distances between the feature points is greater than a set distance threshold, it is determined that the output characteristic curve has a significant difference.

[0034] Optionally, when it is determined that an abnormal photovoltaic string or an abnormal combination of strings occurs, the method further includes:

[0035] The output characteristic curve shape of the abnormal photovoltaic string or abnormal string combination is matched with the typical curve shapes of various types of faults saved in advance, and the fault type is determined according to the matching result.

[0036] Optionally, when an abnormal string combination is determined, the method further includes:

[0037] Obtaining the operating data of the photovoltaic strings or string sub-combinations included in the abnormal string combination;

[0038] The photovoltaic strings or string sub-combinations are used as matching photovoltaic strings or matching string combinations, and data comparison of the matching photovoltaic strings or matching string combinations is performed.

[0039] According to another aspect of the present invention, there is further provided a computer program product, comprising a computer program, characterized in that when the computer program is executed by a processor, the steps of any of the above-mentioned methods for detecting abnormalities of strings in a photovoltaic power station are implemented.

[0040] According to another aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, any of the above-mentioned methods for detecting abnormalities of strings in a photovoltaic power station is implemented.

[0041] According to another aspect of the present invention, there is also provided a photovoltaic power station system, comprising:

[0042] Multiple photovoltaic strings, each of which is composed of multiple photovoltaic cell monomers connected in series;

[0043] A current sensor is used to measure the current data of a photovoltaic string and a string combination, wherein the string combination is composed of a plurality of photovoltaic strings connected;

[0044] Voltage sensor, used to measure the voltage data of photovoltaic strings and string combinations;

[0045] A controller comprises a memory, a processor and a computer program stored in the memory, wherein when the computer program is executed by the processor, the steps of any of the above-mentioned methods for detecting abnormalities of strings in a photovoltaic power station are implemented.

[0046] According to another aspect of the present invention, a computer program product is provided, comprising a computer program, which implements the steps of any of the above-mentioned methods for detecting abnormalities of strings in a photovoltaic power station when executed by a processor.

[0047] The method for detecting abnormal strings in a photovoltaic power station of the present invention searches for matching photovoltaic strings or matching string combinations with similar operating data characteristics from the photovoltaic power station, extracts photovoltaic operating data of each matching photovoltaic string or matching string combination within a preset peak illumination period, and uses the photovoltaic operating data for comparison. Since the matching photovoltaic strings or matching string combinations have the same operating environment, the solar illumination, temperature, etc. are basically the same, and under normal operating conditions, the difference in photovoltaic operating data is small, so abnormal photovoltaic strings or abnormal string combinations can be determined by comparing photovoltaic operating data. This detection method can improve the accuracy of detection by preventing errors in judgment due to the inability of the preset threshold to reflect changes in actual operating conditions. In addition, the method of this embodiment uses photovoltaic operating data within a preset peak illumination period for judgment, which further eliminates interference factors.

[0048] Furthermore, the method for detecting abnormalities of photovoltaic strings in a photovoltaic power station of the present invention can use the circuit connection topology, the location of the photovoltaic strings and the surrounding terrain information, or historical operation data to determine matching photovoltaic strings or matching string combinations for comparison with each other, and use the data between matching photovoltaic strings or matching string combinations for comparison. The detection algorithm is efficient and simple, which reduces the number of sensors and other equipment used and reduces costs.

[0049] Furthermore, the method for detecting abnormality of a photovoltaic power station string in the present invention can use the output current-voltage characteristic curve and / or the output power-voltage characteristic curve for difference comparison. Still further, the method for detecting abnormality of a photovoltaic power station string in the present invention can compare data layer by layer, gradually narrow the abnormal range, and realize abnormal location.

[0050] Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0052] Figure 1 is an electrical connection diagram of a photovoltaic power station system according to an embodiment of the present invention;

[0053] Figure 2 is a schematic diagram of a method for detecting abnormality of a photovoltaic string in a photovoltaic power station according to an embodiment of the present invention;

[0054] Figure 3 is a schematic diagram of a method for detecting abnormality of a photovoltaic string in a photovoltaic power station according to another embodiment of the present invention;

[0055] Figure 4 is a comparison diagram of IV output characteristic curves of photovoltaic strings in a normal state and an abnormal state in a method for detecting abnormality of photovoltaic strings in a photovoltaic power station according to an embodiment of the present invention;

[0056] Figure 5 is a comparison diagram of IV output characteristic curves of typical faults in a method for detecting abnormality of a photovoltaic power station string according to an embodiment of the present invention;

[0057] Figure 6 is a schematic diagram of a computer program product according to an embodiment of the present invention;

[0058] Figure 7 is a schematic diagram of a computer-readable storage medium according to an embodiment of the present invention;

[0059] Figure 8 is a schematic diagram of a controller in a photovoltaic power station system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0060] The embodiments of the present invention provide a method for detecting string anomalies in a photovoltaic power station, which can accurately locate faults, help to fine-tune the operation and maintenance of photovoltaic power stations, and improve the energy efficiency of photovoltaic power generation systems.

[0061] Photovoltaic module (PV module) is a smallest indivisible solar cell combination device with internal connections of a packaging machine that can independently provide DC power output. It is also called a solar cell module, solar panel or photovoltaic cell monomer.

[0062] Photovoltaic modules string, in the photovoltaic power generation system, several photovoltaic modules are connected in series to form a circuit unit with a certain DC output. Photovoltaic array (PV array) is a DC power generation unit composed of several photovoltaic modules assembled together mechanically and electrically in a certain way and with a fixed support structure, also known as a photovoltaic array.

[0063] Figure 1 : is an electrical connection diagram of a photovoltaic power station system according to an embodiment of the present invention. The photovoltaic power station system includes multiple photovoltaic strings PVS, a current sensor I, and a voltage sensor U. Each photovoltaic string PVS is composed of multiple photovoltaic cell monomers PV in series. Multiple photovoltaic strings PVS are connected to form a string combination. In some embodiments, multiple small string combinations can be further composed of a larger string combination. In other words, the photovoltaic power station system is built layer by layer by photovoltaic cell monomers PV, photovoltaic strings PVS, and at least one level of string combination. For example, the photovoltaic power station system can adopt an SP circuit structure, that is, after multiple photovoltaic cell monomers PV are connected in series to form a photovoltaic string PVS, the photovoltaic strings PVS are then connected in series and in parallel to form a string combination. Alternatively, the photovoltaic power station system can adopt a TCT circuit structure, that is, multiple photovoltaic cell monomers PV are first connected in parallel to form a parallel unit, and then further connected in series to form a photovoltaic string PVS, and then the photovoltaic strings PVS are connected in series and in parallel to form a string combination.

[0064] The current sensor I is used to measure the current data of the photovoltaic string PVS and the combination of strings. The voltage sensor U is used to measure the voltage data of the photovoltaic string PVS and the combination of strings. The number and installation time of the current sensor I and the voltage sensor U can be configured according to the electrical connection structure of the photovoltaic power station system.

[0065] Figure 1 An example is shown in which four photovoltaic cell monomers PV are connected in series to form a photovoltaic string PVS, and three photovoltaic strings PVS are further combined into a string combination, wherein the number of photovoltaic cell monomers PV and photovoltaic strings PVS is only an example, and those skilled in the art can design the electrical topology connection structure of the photovoltaic power station according to specific needs and component characteristics.

[0066] Since the output power of solar cells is not maintained at the highest at any voltage, but there is a specific voltage (called the maximum power point voltage, Vmp) and the corresponding current (Imp) combination, under which the maximum power output (Pmp) can be obtained. Since changes in factors such as light intensity and temperature will affect the operating curve of solar cells, the inverter of this embodiment (not shown in the figure) can continuously detect and adjust the working point of the photovoltaic string PVS to keep it near the maximum power point, thereby improving the energy conversion efficiency and power generation of the entire system. The inverter can use methods such as perturbation observation method, incremental conductance method, constant voltage method, etc. to track this maximum power point in real time, and perform electrical energy conversion at the same time, converting unstable and non-optimal voltages into optimal voltages suitable for battery energy storage systems or grid connections, and ultimately achieving efficient energy collection and transmission.

[0067] This embodiment also provides a method for detecting abnormal strings in a photovoltaic power station, which is used to accurately identify abnormal strings or abnormal string combinations in the photovoltaic power station system, repair faults in time, and improve operation and maintenance efficiency. The abnormal string faults may include: the problem of solar panel cracks, the problem of string drop (or array mismatch) caused by aging and damage, and the photovoltaic array hot spot phenomenon. The problem of solar panel cracks refers to the problem that due to the manufacturing process and the harsh environment in which the photovoltaic panels are installed, cracks will appear on the surface of the photovoltaic cells after years of wind and sun, causing corrosion to the photovoltaic cells. Over time, the life of the photovoltaic cells decreases. After the panels have been working for a long time, the panels themselves, the lines, and the connectors gradually age and damage, causing string drop mismatch, and even unable to work normally. The hot spot phenomenon is mainly caused by local shading. When the solar panel is partially blocked for a long time, the local current is less than the unblocked part. The solar panel blocked by the block section consumes the energy generated by other normally working photovoltaic cells in the form of heat. The heat accumulation will damage the packaging materials of the photovoltaic panels, destroy the physical structure of the photovoltaic panels, and even cause permanent damage.

[0068] Figure 2 is a schematic diagram of a method for detecting abnormality of a photovoltaic string in a photovoltaic power station according to an embodiment of the present invention. The steps of the method for detecting abnormality of a photovoltaic string may include:

[0069] Step S201, data monitoring and collection: monitoring the operation data of the photovoltaic strings, including key parameters such as voltage, current, power, etc.; transmitting these data to the data processing center (or monitoring center) in real time through sensors and data acquisition systems;

[0070] Step S202, data preprocessing: cleaning and preprocessing the collected data, removing outliers, ensuring the accuracy and reliability of the data, and excluding obviously erroneous measurement data;

[0071] Step S203, data determination: compare the processed data with a preset threshold. The threshold is usually determined based on the specifications of the component, historical operating data, and industry standards. If the data exceeds or falls below the preset threshold range, it may indicate that the string is abnormal.

[0072] Step S204, fault diagnosis and location: use the current difference method to locate the abnormal string so that the operation and maintenance personnel can quickly find and handle the fault.

[0073] This method uses a fixed threshold as the basis for judgment. Since the working state of the photovoltaic string is affected by the sunshine, temperature, aging degree of the solar panel, etc., the preset threshold cannot accurately reflect the changes of the above influences, which may lead to wrong judgment or misjudgment. Based on this consideration, this embodiment also provides another method for detecting abnormality of the photovoltaic string in the photovoltaic power station. Figure 3 is a schematic diagram of a method for detecting abnormality of a photovoltaic string in a photovoltaic power station according to another embodiment of the present invention. The steps of the method for detecting abnormality of a photovoltaic string may include:

[0074] Step S301, obtaining photovoltaic operation data measured by sensors in the photovoltaic power station; the photovoltaic operation data may include current data of photovoltaic strings or string combinations measured by current sensors, voltage data of photovoltaic strings or string combinations measured by voltage sensors, and power data of photovoltaic strings or string combinations further calculated based on current data and voltage data.

[0075] Step S302, searching for matching photovoltaic strings or matching string combinations with similar operating data characteristics from the photovoltaic power station; matching photovoltaic strings or matching string combinations can be considered as photovoltaic strings or string combinations that can output similar current, voltage, and power during normal operation. Matching photovoltaic strings can have the same specifications and operating environment. Matching string combinations can have the same string connection structure and operating environment to ensure the same or similar output characteristics under normal working conditions.

[0076] Determining matching PV strings or matching strings can be achieved through electrical connection relationships, such as obtaining the string connection topology of the PV power station; determining the PV strings or string combinations connected to the same inverter based on the string connection topology as matching PV strings or matching string combinations. PV strings or string combinations connected to the same inverter are generally required to be consistent, so PV strings or string combinations connected to the same inverter can be used as comparison targets.

[0077] Determining matching photovoltaic strings or matching strings can also be achieved through positional relationships, such as obtaining the location of the photovoltaic strings of the photovoltaic power station and the surrounding terrain information; using photovoltaic strings or string combinations that are adjacent in location and have similar surrounding terrain as matching photovoltaic strings or matching string combinations. The above-mentioned surrounding terrain information may include: height, slope, slope direction, etc. Photovoltaic strings or string combinations that are adjacent in location and have similar surrounding terrain can have similar solar illumination conditions, so these photovoltaic strings or string combinations can be used as comparison targets with each other. In some embodiments, the location of the photovoltaic strings of the photovoltaic power station and the surrounding terrain information can be collected and recorded in advance. When it is necessary to determine matching photovoltaic strings or matching strings, these pre-collected and recorded contents are used for analysis to determine matching photovoltaic strings or matching string combinations for mutual comparison.

[0078] Determining matching PV strings or matching strings can also be achieved through historical data, such as obtaining historical operating data of each PV string and string combination in the PV power station during the peak light period; matching PV strings and string combinations with similar operating data characteristic curves as matching PV strings or matching string combinations according to historical operating data. The above-mentioned peak light period selects a period with sufficient light, generally from 10 am to 2 pm, or from 12 pm to 14 pm. The specific peak light period can be set according to the light conditions. Using the photovoltaic operating data within the preset peak light period for judgment can further eliminate interference factors. If the historical operating data is relatively close, if there is a sudden difference, it can also be determined that an abnormality has occurred. Therefore, PV strings or string combinations with similar historical data can be used as comparison targets.

[0079] In some embodiments, the method of this embodiment can acquire and process data during the time period when the photovoltaic strings stop converting energy. For example, abnormal detection of photovoltaic strings can be performed during the period when there is no light in the early morning. In this way, on the one hand, the idle computing power of the controller for photovoltaic string control can be used. On the other hand, work order generation can be completed before the photovoltaic operation starts, and processing can be performed in time.

[0080] Step S303, respectively extracting photovoltaic operation data of each matching photovoltaic string or matching string combination during a preset peak light period as comparison data. These comparison data are all measurement results of current, voltage, and power of the photovoltaic string or string combination.

[0081] Step S304, compare the comparison data of the matching photovoltaic strings or the matching string combination, and determine the abnormal photovoltaic strings or the abnormal string combination according to the comparison result. An optional comparison method is: compare the size of the comparison data respectively; if the relative ratio of the comparison data of any photovoltaic string or string combination in the matching photovoltaic string or the matching string combination to the comparison data of other photovoltaic strings or string combinations is greater than a preset threshold, it is determined that an abnormal photovoltaic string or an abnormal string combination occurs. For example, for two photovoltaic strings PV1 and PV2 connected to the same inverter, under normal conditions, the current, voltage, and power output by PV1 and PV2 should be close. If the current (or voltage) of PV1 becomes a certain multiple (for example, 1.5 times) of PV2 or the current (or voltage) of PV2 becomes a certain multiple (for example, 1.5 times) of PV1, it can be determined that one of the two photovoltaic strings PV1 and PV2 is abnormal.

[0082] The method of the above embodiment searches for matching photovoltaic strings or matching string combinations with similar operating data characteristics from the photovoltaic power station, extracts the photovoltaic operating data of each matching photovoltaic string or matching string combination within the preset peak illumination period, and uses the photovoltaic operating data for comparison. Since the matching photovoltaic strings or matching string combinations have the same operating environment, the solar illumination, temperature, etc. are basically the same, and under normal operating conditions, the difference in photovoltaic operating data is small. Therefore, by comparing the photovoltaic operating data, abnormal photovoltaic strings or abnormal string combinations can be determined. This detection method can avoid the situation where the preset threshold cannot be updated with changes in actual operating conditions, resulting in incorrect judgments. In addition, the method of this embodiment uses the photovoltaic operating data within the preset peak illumination period for judgment, which further eliminates interference factors.

[0083] In order to further improve the accuracy of detection, the method of this embodiment can also use the output characteristic curve (output current-voltage characteristic curve and / or output power-voltage characteristic curve) to perform data comparison, make full use of the data, make the detection more accurate, and facilitate further determination of the fault type.

[0084] The output current-voltage characteristic curve (Current-Voltage, or IV) refers to a curve of the output current characteristics of a photovoltaic string or string combination under different applied voltages, which represents the nonlinear relationship between the output current and voltage of a photovoltaic string or string combination under different working conditions. The IV curve can be used to understand the maximum power, maximum efficiency, and performance changes with temperature and light intensity.

[0085] The output power-voltage characteristic curve (Power-Voltage, PV) is the relationship curve between the output power of a photovoltaic string or a combination of strings and its voltage under different voltage conditions. The PV curve is usually "hump-shaped". As the voltage increases, the power begins to rise (because the current drops slower than the voltage rises). After reaching the peak, as the voltage increases further, the power decreases rapidly due to the sharp drop in current. In actual photovoltaic systems, inverters or other power electronic devices will use maximum power point tracking (MPPT) technology to continuously adjust the operating voltage of the photovoltaic array to ensure that the system always operates at the maximum power point on the PV curve to maximize the use of solar energy resources. The PV curve reflects the performance response of the photovoltaic string or combination of strings when the temperature and irradiance change, as well as the degree of decline under aging, pollution and other conditions.

[0086] In an embodiment using output characteristic curves for comparison, step S304 of comparing comparison data of matching photovoltaic strings or matching string combinations may include: generating output characteristic curves (output current-voltage characteristic curves and / or output power-voltage characteristic curves) based on the comparison data of matching photovoltaic strings or matching string combinations; comparing the output characteristic curves of matching photovoltaic strings or matching string combinations to determine whether there are obvious differences in the output characteristic curves; if there are obvious differences, determining that an abnormal photovoltaic string or abnormal string combination has occurred.

[0087] The step of comparing the output characteristic curves of the matching photovoltaic strings or matching string combinations may include: extracting characteristic points of the output characteristic curves, the characteristic points including: peak values, valley values, and inflection points; respectively calculating the distances between the characteristic points; and determining that the output characteristic curves have obvious differences when the sum of the distances between the characteristic points is greater than a set distance threshold. For example, after analyzing the output characteristic curves, the number, relative position, and type (peak value, valley value, inflection point, etc.) of the characteristic points can be determined. By comparing the characteristic points of the output characteristic curves of the matching photovoltaic strings or matching string combinations, those skilled in the art can determine that there are obvious differences between the output characteristic curves, and further determine whether there are abnormalities in the matching photovoltaic strings or matching string combinations.

[0088] Figure 4 It is a comparison diagram of the IV output characteristic curves of the photovoltaic strings in the normal state and the abnormal state in the detection method of the abnormality of the photovoltaic string in the photovoltaic power station according to one embodiment of the present invention. There is a significant difference between the IV output characteristic curve L11 of the photovoltaic string in the normal state and the IV output characteristic curve L12 in the abnormal state, which can be determined by the analysis of the characteristic points. In this embodiment, this feature is used to identify abnormal photovoltaic strings or abnormal string combinations. Similarly, those skilled in the art can also use the output power-voltage characteristic curve PV curve for judgment.

[0089] When it is determined that an abnormal photovoltaic string or abnormal combination of strings occurs, the method may further include: matching the output characteristic curve shape of the abnormal photovoltaic string or abnormal combination of strings with the pre-stored typical curve shapes of various types of faults, and determining the fault type according to the matching result. The typical curves of various types of faults can be obtained by collecting and synthesizing data when various types of faults occur in advance. Figure 5 It is a comparison diagram of IV output characteristic curves of typical faults in a method for detecting abnormality of a photovoltaic string in a photovoltaic power station according to an embodiment of the present invention. Among them, IV output characteristic curve L21, IV output characteristic curve L22, IV output characteristic curve L23, and IV output characteristic curve L24 are respectively the IV output characteristic curves of a normal photovoltaic string, an aged photovoltaic string, a partially short-circuited photovoltaic string, and a photovoltaic string with a light spot shadow. By matching the typical curve shapes of various types of faults, the fault type can be determined for processing.

[0090] In the case of determining an abnormal string combination, the method of this embodiment can also obtain the operating data of the photovoltaic strings or string sub-combinations contained in the abnormal string combination; use the photovoltaic strings or string sub-combinations as matching photovoltaic strings or matching string combinations, and perform data comparison of matching photovoltaic strings or matching string combinations. This process can further narrow the scope of the fault. A step-by-step abnormality detection method is to first perform a data comparison of matching string combinations on several large string combinations contained in the photovoltaic power station. If a certain string combination is determined to be abnormal, the data of the lower-level string combinations contained in the string combination is compared, and then matched step by step to finally determine the photovoltaic string or a smaller string combination. The above process iteratively executes the steps of data comparison of photovoltaic strings or matching string combinations to gradually narrow the scope of the fault.

[0091] This embodiment also provides a computer program product 112 , a computer-readable storage medium 113 , and a photovoltaic power station design device 30 . Figure 6 is a schematic diagram of a computer program product 112 according to one embodiment of the present invention, Figure 7 is a schematic diagram of a computer-readable storage medium 113 according to an embodiment of the present invention, Figure 81 is a schematic diagram of a controller 130 in a photovoltaic power station system according to an embodiment of the present invention. The computer program product 112 includes a computer program 111, which, when executed by a processor 310, implements the steps of any of the above-mentioned methods for detecting abnormalities of strings in a photovoltaic power station. The computer-readable storage medium 113 stores the above-mentioned computer program 111, which, when executed by a processor 310, implements the steps of any of the above-mentioned methods for controlling a machine of a household photovoltaic energy storage system. The controller 130 may include a memory 320, a processor 310, and a computer program 111 stored in the memory 320 and running on the processor 310.

[0092] The computer program 111 for performing the operation of the present invention may be an assembly instruction, an instruction set architecture (ISA) instruction, a machine instruction, a machine-dependent instruction, a microcode, a firmware instruction, a state setting data, a configuration data of an integrated circuit, or a source code or an object code written in any combination of one or more programming languages ​​and a procedural programming language. The computer program 111 may be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer may be connected to the user's computer via any type of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet Service Provider). In some embodiments, to perform aspects of the present invention, electronic circuits including, for example, programmable logic circuits, Field-Programmable Gate Arrays (FPGAs), or Programmable Logic Arrays (PLAs) may execute computer-readable program instructions by utilizing state information of the computer-readable program instructions to personalize the electronic circuits.

[0093] In the description of this embodiment, the computer program product 112 is a related product including the computer program 111 .

[0094] For the purposes of the description of this embodiment, the computer-readable storage medium 113 is a tangible device capable of retaining and storing the computer program 111, which may be any device that can contain, store, communicate, propagate or transmit the program 111 for use with or in conjunction with an instruction execution system, device or apparatus. More specific examples (a non-exhaustive list) of the computer-readable storage medium 113 include the following: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, and any suitable combination of the foregoing.

[0095] At this point, those skilled in the art should recognize that, although multiple exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived based on the content disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all these other variations or modifications.

Claims

1. A method for detecting abnormality of a photovoltaic string in a photovoltaic power station, comprising: Acquire photovoltaic operation data measured by sensors in the photovoltaic power station; the sensors include current sensors for measuring current data of photovoltaic strings or string combinations and voltage sensors for measuring voltage data of the photovoltaic strings or string combinations; Searching for matching photovoltaic strings or matching string combinations with similar operating data characteristics from the photovoltaic power station, wherein the matching photovoltaic strings and the matching string combinations are photovoltaic strings and string combinations that output similar current, voltage, and power during normal operation; Respectively extracting the photovoltaic operation data of each matching photovoltaic string or the matching string combination during a preset peak illumination period as comparison data; Comparing the comparison data of the matching photovoltaic strings or matching string combinations, and determining the abnormal photovoltaic strings or abnormal string combinations according to the comparison results; The step of comparing the comparison data of the matching photovoltaic strings or the matching string combination includes: generating an output characteristic curve according to the comparison data of the matching photovoltaic strings or the matching string combination, wherein the output characteristic curve includes: an output current-voltage characteristic curve and / or an output power-voltage characteristic curve; comparing the output characteristic curves of the matching photovoltaic strings or the matching string combination to determine whether there is a significant difference in the output characteristic curves; if there is a significant difference, determining that an abnormal photovoltaic string or an abnormal string combination exists; The step of comparing the output characteristic curves of the matched photovoltaic strings or the matched string combinations comprises: extracting characteristic points of the output characteristic curves, the characteristic points comprising: peak values, valley values, and inflection points; respectively calculating the distances between the characteristic points; and determining that the output characteristic curves have obvious differences when the sum of the distances between the characteristic points is greater than a set distance threshold; When the abnormal string combination is determined, the method further includes: Acquiring operation data of the photovoltaic strings or string sub-combinations included in the abnormal string combination; The photovoltaic strings or string sub-combinations are used as matching photovoltaic strings or matching string combinations, and data comparison of the matching photovoltaic strings or matching string combinations is performed.

2. The method for detecting abnormality of a photovoltaic power station string according to claim 1, wherein: The step of comparing the comparison data of the matching photovoltaic strings or the matching string combinations also includes: Respectively comparing the sizes of the comparison data; If the relative ratio of the comparison data of any photovoltaic string or string combination in the matching photovoltaic string or the matching string combination to the comparison data of other photovoltaic strings or string combinations is greater than a preset ratio threshold, it is determined that an abnormal photovoltaic string or abnormal string combination occurs.

3. The method for detecting abnormality of a photovoltaic power station string according to claim 1, wherein: The step of searching for a matching photovoltaic string or a matching string combination having similar operating data characteristics from the photovoltaic power station includes: Obtaining a string connection topology relationship of the photovoltaic power station; A photovoltaic string or a combination of strings connected to the same inverter is determined according to the string connection topology as the matching photovoltaic string or the matching string combination.

4. The method for detecting abnormality of a photovoltaic power station string according to claim 1, wherein: The step of searching for a matching photovoltaic string or a matching string combination having similar operating data characteristics from the photovoltaic power station includes: Obtaining the location of the photovoltaic strings of the photovoltaic power station and surrounding terrain information; Photovoltaic strings or string combinations that are adjacent in location and have similar surrounding terrain are used as the matching photovoltaic strings or matching string combinations.

5. The method for detecting abnormality of a photovoltaic power station string according to claim 1, wherein: The step of searching for a matching photovoltaic string or a matching string combination having similar operating data characteristics from the photovoltaic power station includes: Acquire historical operation data of each photovoltaic string and string combination of the photovoltaic power station during the peak sunshine period; Photovoltaic strings and string combinations with similar operating data characteristic curves are matched according to the historical operating data as the matching photovoltaic strings or matching string combinations.

6. The method for detecting abnormality of a photovoltaic power station string according to claim 1, wherein: When an abnormal photovoltaic string or abnormal combination of strings is determined, it also includes: The output characteristic curve shape of the abnormal photovoltaic string or abnormal string combination is matched with the pre-stored typical curve shapes of various faults, and the fault type is determined according to the matching result.

7. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method for detecting abnormality of a photovoltaic string in a photovoltaic power station according to any one of claims 1 to 6 are implemented.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that When the computer program is executed by a processor, the method for detecting abnormality of a photovoltaic string in a photovoltaic power station according to any one of claims 1 to 6 is implemented.

9. A photovoltaic power station system, comprising: A plurality of photovoltaic strings, each of which is composed of a plurality of photovoltaic battery cells connected in series; A current sensor, used to measure current data of the photovoltaic string and the string combination, wherein the string combination is composed of a plurality of the photovoltaic strings connected; A voltage sensor, used to measure voltage data of the photovoltaic string and the combination of the strings; A controller comprising a memory, a processor and a computer program stored in the memory, wherein when the computer program is executed by the processor, the steps of the method for detecting abnormality of a photovoltaic string in any one of claims 1 to 6 are implemented.

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