Photovoltaic array detection method and system

Abstract

The invention provides a photovoltaic array detection method and system, the method is applied to the photovoltaic array detection system, and the photovoltaic array detection method comprises the steps: obtaining the number of connected photovoltaic branches in a photovoltaic array; determining reference electrical parameters according to the number of the photovoltaic branches and the electrical parameters of the photovoltaic branches; under the condition that the photovoltaic array is electrically connected with the photovoltaic array detection system, testing electrical parameters of the photovoltaic array are monitored; and determining a detection result of the photovoltaic array according to the test electrical parameter and the reference electrical parameter.

Description

Photovoltaic array detection method and system Technical Field

[0001] The present application relates to the field of photovoltaic power generation technology, and in particular to a photovoltaic array detection method and system. Background Art

[0002] Before a photovoltaic array is put into operation, it is usually necessary to inspect it. Current inspection methods use loop current and voltage detection, performing a global scan and comparing the data with preset values. The difference is used to determine whether there are any abnormalities in the loop.

[0003] Summary of the Invention

[0004] In view of this, an object of the embodiments of the present application is to provide a photovoltaic array detection method and system to improve the limitations of photovoltaic branch detection in the prior art.

[0005] In a first aspect, an embodiment of the present application provides a photovoltaic array detection method, which is applied to a photovoltaic array detection system. The photovoltaic array detection method includes: obtaining the number of photovoltaic branches connected to the photovoltaic array; determining reference electrical parameters based on the number of the photovoltaic branches and the electrical parameters of the photovoltaic branches; obtaining test electrical parameters of the photovoltaic array when the photovoltaic array is electrically connected to the photovoltaic array detection system; and determining the detection results of the photovoltaic array based on the test electrical parameters and the reference electrical parameters.

[0006] In an optional embodiment, when the photovoltaic array is electrically connected to the photovoltaic array detection system, the test electrical parameters of the photovoltaic array are obtained, including: when the photovoltaic array is powering the photovoltaic array detection system, monitoring the test electrical parameters input by the photovoltaic array to the photovoltaic array detection system.

[0007] In the above embodiment, the photovoltaic array is used as a power supply device to detect the power supply status of the photovoltaic array.

[0008] In an optional embodiment, the reference electrical parameter includes a first reference current, the electrical parameter of the photovoltaic branch includes the first reference current of the photovoltaic branch, and the test electrical parameter includes a first test current;

[0009] Determining the reference electrical parameters according to the number of the photovoltaic branches and the electrical parameters of the photovoltaic branches includes: determining the reference current of a single photovoltaic branch of the photovoltaic array according to the characteristic parameters of the single photovoltaic branch; determining the first reference current of the photovoltaic array according to the number of the photovoltaic branches and the reference current of the photovoltaic branch;

[0010] The determining of the detection result of the photovoltaic array based on the test electrical parameters and the reference electrical parameters includes: comparing the first test current with the first reference current; if the difference between the first test current and the first reference current is greater than a first current threshold, determining that an abnormality exists in the photovoltaic array.

[0011] In the above embodiment, when determining the reference current, the number of effective photovoltaic branches of the photovoltaic array may be included in the calculation, so that the calculated first reference current can be more accurate, thereby making the result of detecting the photovoltaic array more accurate.

[0012] In an optional embodiment, determining the reference current of a single photovoltaic branch of the photovoltaic array based on the electrical parameters of the single photovoltaic branch includes: determining a first initial current of the photovoltaic branch based on the characteristic parameters of the single photovoltaic branch under multiple working states; and determining the reference current of the photovoltaic branch based on the first initial current under multiple working states.

[0013] In an optional embodiment, the characteristic parameters include the photocurrent and loss current of the photovoltaic branch;

[0014] Determining the first initial current of the photovoltaic branch based on the characteristic parameters of the photovoltaic branch includes: obtaining the photocurrent generated by a single photovoltaic branch; obtaining the loss current of the single photovoltaic branch; and determining the first initial current of the photovoltaic branch based on the photocurrent and the loss current.

[0015] In the above embodiment, when determining the first reference current, the loss current in the photovoltaic array is also taken into consideration, so that the determined first reference current can be more accurate, and further, the result of detecting the photovoltaic array can also be more accurate.

[0016] In an optional embodiment, determining the reference current of the photovoltaic branch based on the first initial current under multiple working states includes: screening out the current corresponding to the photovoltaic branch power being greater than the set power from the first initial current under multiple working states as the reference current of the photovoltaic branch.

[0017] In the above embodiment, it is considered that when the photovoltaic array is supplying power, it will automatically select the current corresponding to the maximum power point as the output working current. Therefore, when determining the reference current, it will be screened based on this standard, so that the test can be closer to the normal working state of the photovoltaic array, and the test results of the photovoltaic array can be more accurate.

[0018] In an optional embodiment, the reference electrical parameter includes a first reference voltage, and the test electrical parameter includes a first test voltage;

[0019] The determining of the detection result of the photovoltaic array based on the test electrical parameters and the reference electrical parameters includes: comparing the first test voltage with the first reference voltage; if the difference between the first test voltage and the first reference voltage is greater than a first voltage threshold, determining that an abnormality exists in the photovoltaic array.

[0020] In the above embodiment, the voltage of the photovoltaic array may also be detected, so that the detection result of the photovoltaic array may be more comprehensive.

[0021] In an optional embodiment, the photovoltaic array detection system includes: a power supply module;

[0022] The step of obtaining test electrical parameters of the photovoltaic array when the photovoltaic array is electrically connected to the photovoltaic array detection system includes:

[0023] When the power module of the photovoltaic array detection system is supplying power to the photovoltaic array, the test electrical parameters of the photovoltaic array are monitored.

[0024] In the above embodiment, a second power supply may be provided to the photovoltaic array, so that the working condition of the photovoltaic array and the conditions of the internal components in the photovoltaic array can be more comprehensively detected.

[0025] In an optional embodiment, the reference electrical parameter includes a second reference current, the electrical parameter of the photovoltaic branch includes the second reference current of the photovoltaic branch, and the test electrical parameter includes a second test current;

[0026] Determining the reference electrical parameters based on the number of photovoltaic branches and the electrical parameters of the photovoltaic branches includes: obtaining, for each photovoltaic branch, the load current of all load elements in the photovoltaic branch; determining a second reference current of the photovoltaic branch based on the load current of all load elements; and determining a second reference current of the photovoltaic array based on the number of photovoltaic branches and the second reference current of the photovoltaic branch;

[0027] The determining of the detection result of the photovoltaic array based on the test electrical parameters and the reference electrical parameters includes: comparing the second test current with the second reference current; if the difference between the second test current and the second reference current is greater than a second current threshold, determining that an abnormality exists in the photovoltaic array.

[0028] In the above embodiment, since the photovoltaic branch is not actively powered, there is no photogenerated current in the photovoltaic branch. Therefore, a reference current different from that when the photovoltaic array is actively powered can be determined. This method of determining the reference current is more consistent with the operating conditions of the second operation and can also achieve detection of the photovoltaic array in this situation.

[0029] In an optional embodiment, the reference electrical parameter includes a second reference voltage, and the test electrical parameter includes a second test voltage;

[0030] The determining of the detection result of the photovoltaic array based on the test electrical parameters and the reference electrical parameters includes: comparing the second test voltage with the second reference voltage; if the difference between the second test voltage and the second reference voltage is greater than a second voltage threshold, determining that an abnormality exists in the photovoltaic array.

[0031] In the above embodiment, the voltage under the second power supply may also be compared to more comprehensively determine whether there is an abnormality in the photovoltaic array.

[0032] In an optional embodiment, the method further includes:

[0033] The number of connected photovoltaic branches is compared with the total number of photovoltaic branches included in the photovoltaic array to determine whether the number of connected photovoltaic branches is less than the total number of photovoltaic branches included in the photovoltaic array; if the number of connected photovoltaic branches is less than the total number of photovoltaic branches included in the photovoltaic array, it is determined that there is an access abnormality in the photovoltaic array.

[0034] In the above embodiment, the number of photovoltaic branches actually included in the photovoltaic array can be compared with the number of branches successfully connected to the detection system to determine whether there is any connection abnormality in the photovoltaic array, so as to more accurately locate various types of photovoltaic array abnormalities.

[0035] In a second aspect, an embodiment of the present application provides a photovoltaic array detection system, comprising: a photovoltaic storage inverter; the photovoltaic storage inverter comprises: an input interface, a converter, and a central controller;

[0036] The input interface is used to connect to the photovoltaic array;

[0037] The converter is used to detect the electrical parameters of the photovoltaic array;

[0038] The solar-storage inverter executes the steps of the above method when it is running.

[0039] In an optional embodiment, it further includes: a power supply module connected to the photovoltaic storage inverter;

[0040] The power supply module is used to provide a second power supply to the photovoltaic array.

[0041] The photovoltaic array detection method and system provided in the embodiments of the present application detect the number of photovoltaic branches connected to the detection system, which can avoid misjudgment caused by lack of connection; in addition, reference electrical parameters can be determined based on the number of connected photovoltaic branches, which can make the determined reference values ​​more valuable, thereby more accurately determining whether there is a circuit abnormality in the photovoltaic array.

[0042] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the following embodiments are given in conjunction with the accompanying drawings for detailed description as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0044] FIG1 is a schematic structural diagram of a photovoltaic array detection system provided in an embodiment of the present application;

[0045] FIG2 is a flow chart of a photovoltaic array detection method provided in an embodiment of the present application;

[0046] FIG3 is an optional flow chart of step 320 of the photovoltaic array detection method provided in an embodiment of the present application;

[0047] FIG4 is an equivalent circuit diagram of a photovoltaic branch;

[0048] FIG5 is another optional flow chart of step 320 of the photovoltaic array detection method provided in an embodiment of the present application;

[0049] FIG6 is an equivalent circuit diagram of a photovoltaic branch in a powered state.

[0050] Icons: 100-PV array detection system; 110-PV storage inverter; 111-converter; 112-input interface; 113-DCAC inverter; 114-manual switch; 115-first current sensor; 116-detection controller; 117-PV voltage; 118-central controller; 120-power module; 130-DCDC converter; 200-PV array. DETAILED DESCRIPTION

[0051] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings in the embodiments of the present application.

[0052] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and should not be understood as indicating or implying relative importance.

[0053] A photovoltaic array is a system of connected photovoltaic modules. Each photovoltaic module can include multiple photovoltaic cells. A photovoltaic array is a photovoltaic power generation system. Photovoltaic arrays can be charged by solar energy. They are relatively clean and have a large available supply. Therefore, photovoltaic arrays are being used in more and more scenarios. In order to make the power supply of the photovoltaic arrays used more stable and safe, they need to be tested before they are put into use. The current testing method is to perform a global scan of the photovoltaic array through loop current and voltage detection and compare the data with the preset values. The difference is used to determine whether there is any abnormality in the loop.

[0054] The inventors of this application have found that the current detection method, which scans the current and voltage of the photovoltaic array globally, cannot confirm whether the photovoltaic branches in the photovoltaic array are disconnected or the photovoltaic branches are damaged and open, resulting in no input.

[0055] Based on the above research, an embodiment of the present application provides a photovoltaic array detection method and system, which determines the number of connected photovoltaic branches by combining the connector connection signal with the voltage and current signals of the connected photovoltaic array to identify abnormal conditions of the photovoltaic array such as the photovoltaic branch not being connected or having no input.

[0056] To facilitate understanding of this embodiment, a detection system for executing a photovoltaic array detection method disclosed in an embodiment of the present application is first introduced.

[0057] As shown in FIG1 , the photovoltaic array detection system 100 provided in this embodiment may include: a photovoltaic storage inverter 110 .

[0058] The solar-storage inverter 110 includes an input interface 112 , a converter 111 and a central controller 118 .

[0059] The input interface 112 is used to connect to the photovoltaic array 200. The photovoltaic array 200 may include multiple photovoltaic branches, each photovoltaic branch is connected to at least one photovoltaic module, and the photovoltaic module is, for example, a working unit that converts solar energy into electrical energy, so that the photovoltaic array can convert solar energy into electrical energy when in operation and transmit the electrical energy to the photovoltaic storage inverter through the input interface. The photovoltaic storage inverter 110 may include multiple input interfaces 112 (two of which are shown in FIG1 ), each input interface 112 can be used to connect to a photovoltaic branch in the photovoltaic array 200. In one example, the input interface 112 can be a high-voltage input interface.

[0060] The converter 111 is, for example, a direct current-to-direct current (DC-DC) converter. The converter 111 can be used, for example, to detect the electrical parameters of the photovoltaic array 200. The converter 111 can also, for example, convert the electrical energy generated by the photovoltaic array 200 to generate alternating current through the photovoltaic inverter 110 to power the load. In one embodiment, the converter 111 has a maximum power point tracking (MPPT) function. The converter 111 with the MPPT function can detect the power generation voltage of the connected photovoltaic array in real time and track the highest voltage and current values, so that the photovoltaic array can supply power to the load at maximum power output.

[0061] In this embodiment, the maximum power point tracking controller may further include several components. These components form a maximum power point tracking controller that can be used to track the maximum power point of a connected photovoltaic array. As shown in FIG1 , the maximum power point tracking controller may further include several sensors for detecting current or voltage data within the circuit. In the example shown in FIG1 , the maximum power point tracking controller is also connected to a Hall effect sensor (not numbered).

[0062] When the photovoltaic storage inverter 110 is in operation, it can detect the connected photovoltaic arrays, including detecting the number of photovoltaic arrays connected, and detecting the electrical parameters such as voltage and current of the connected photovoltaic arrays. For example, it can detect the number of photovoltaic branches connected to the photovoltaic storage inverter, and detect the voltage and / or current of the photovoltaic branches.

[0063] Please refer to FIG. 1 again, which shows that the photovoltaic array has two photovoltaic branches connected to the input interface 112 of the photovoltaic storage inverter 110 .

[0064] The positive electrode of the photovoltaic branch in the input interface 112 is connected to a first current sensor 115 , which can be used to detect the input current of the photovoltaic array. In a first example, the first current sensor 115 can be a Hall sensor.

[0065] As shown in FIG. 1 , the solar-storage inverter 110 further includes a manual switch 114 connected between the converter 111 and the input interface 112 .

[0066] As shown in FIG1 , the central controller 118 of the solar-storage inverter 110 may be connected to the converter 111 . The central controller 118 may obtain data obtained from a maximum power point tracking function test of the converter 111 .

[0067] The solar-storage inverter 110 in this embodiment may further include a DCAC inverter 113 . The DCAC inverter 113 may be used to convert direct current (DC) into alternating current (AC).

[0068] The DCAC inverter 113 is connected to the converter 111 and is configured to convert the direct current (DC) power transmitted by the converter 111 into alternating current (AC) power.

[0069] In this embodiment, the photovoltaic storage inverter 110 may further include a detection controller 116 , which is connected to the input interface 112 of the photovoltaic storage inverter 110 and is used to detect whether each input interface 112 is connected to a photovoltaic branch to form a loop.

[0070] Exemplarily, the high-voltage input interface can have a low-voltage signal connected to the detection controller 116, which is used to detect the connection status of the male and female heads of the input interface 112. When a photovoltaic branch is connected to the photovoltaic storage inverter 110, the corresponding high-voltage input interface is connected, and the low-voltage signal loop is turned on. The detection controller 116 can detect that the photovoltaic branch of the loop has been connected to the photovoltaic storage inverter 110.

[0071] Alternatively, the positive terminals connected to the input interface 112 can be aggregated to a first node P1, and the negative terminals connected to the input interface 112 can be aggregated to a second node P2. By testing the voltage between the first node P1 and the second node P2, the input voltage of the photovoltaic array 200 can be tested. For example, a voltage sensor can be connected between the first node P1 and the second node P2 to perform voltage testing. In the example shown in FIG1 , the photovoltaic voltage 117 between the first node P1 and the second node P2 can be used to represent the input voltage of the multiple connected photovoltaic branches.

[0072] In this embodiment, the detection system may further include: a power supply module 120 connected to the photovoltaic storage inverter 110 , and the power supply module 120 is used to provide a second power supply to the photovoltaic array 200 .

[0073] As shown in FIG1 , the photovoltaic array detection system 100 may further include a DCDC converter 130 , which is a voltage converter configured to convert an input voltage into a fixed voltage and output the fixed voltage. The DCDC converter 130 is connected between the photovoltaic inverter 110 and the power module 120 .

[0074] As shown in FIG1 , the central controller 118 of the solar-storage inverter 110 can also be connected to the DCAC inverter 113, the DCDC converter 130, and the power module 120. The central controller 118 can obtain relevant data of the DCAC inverter 113, the DCDC converter 130, and the power module 120, and can also control the DCAC inverter 113, the DCDC converter 130, and the power module 120.

[0075] The following describes the relevant contents of the photovoltaic array detection method performed by the photovoltaic array detection system 100 through some methods.

[0076] Please refer to Figure 2, which is a flow chart of the photovoltaic array detection method provided in an embodiment of the present application. The steps in the method provided in this embodiment can be executed by the photovoltaic array detection system shown in Figure 1. The specific process shown in Figure 2 will be described in detail below.

[0077] Step 310: Obtain the number of photovoltaic branches connected to the photovoltaic array.

[0078] Multiple photovoltaic branches of the photovoltaic array are connected to multiple input interfaces of the photovoltaic storage inverter. For example, the number of photovoltaic branches in the photovoltaic array connected to the photovoltaic array detection system can be determined based on the loop formed by the detection controller and the input interface in the photovoltaic array detection system.

[0079] Step 320 : Determine reference electrical parameters according to the number of the photovoltaic branches and the electrical parameters of the photovoltaic branches.

[0080] For example, the reference electrical parameters may include parameters such as voltage and current. The reference electrical parameters may represent electrical parameters that would be generated by the photovoltaic branches of the same number of photovoltaic branches. For example, if the photovoltaic branches of the same number of photovoltaic branches are operating normally, the actually measured electrical parameters may be equal to the reference electrical parameters.

[0081] The reference electrical parameters can be calculated based on the characteristics of the photovoltaic array. For example, if the theoretical output current of each photovoltaic branch is Iref and the number of photovoltaic branches currently connected is N, the reference electrical parameters can be obtained as follows: Imax = N*Iref.

[0082] Step 330 : When the photovoltaic array is electrically connected to the photovoltaic array detection system, obtain test electrical parameters of the photovoltaic array.

[0083] For example, the test electrical parameters input by the photovoltaic array to the photovoltaic array detection system may be obtained by testing when the photovoltaic array is supplying power to the photovoltaic array detection system.

[0084] The test electrical parameters may include electrical parameters such as current and voltage input to the photovoltaic array.

[0085] For example, the input current of the photovoltaic array can be detected by a current sensor in a photovoltaic array detection system. As shown in FIG1 , the input current of the photovoltaic array can be monitored by a first current sensor.

[0086] Optionally, the voltage between the first node P1 and the second node P2 is used to test the input voltage of the photovoltaic array.

[0087] Step 340 : Determine a detection result of the photovoltaic array according to the test electrical parameter and the reference electrical parameter.

[0088] Taking current as an example, if the difference between the current value in the test electrical parameter and the current value in the reference electrical parameter is small, it is determined that the current output of the PV array is not abnormal. For example, if the difference is less than a set threshold, it is determined that the current output of the PV array is not abnormal. The set threshold can be a smaller value set as needed, such as 0.1A, 0.2A, 0.15A, etc. The set threshold can also be a smaller value set based on the current value in the reference electrical parameter, for example, the set threshold can be one-tenth, one-fifteenth, one-twentieth, etc. of the current value in the reference electrical parameter.

[0089] Taking voltage as an example, if the difference between the voltage value in the test electrical parameter and the voltage value in the reference electrical parameter is small, it is determined that the voltage output by the PV array is not abnormal. For example, if the difference is less than a set threshold, it is determined that the voltage output by the PV array is not abnormal. The set threshold can be a smaller value set as needed, such as 0.1V, 0.05V, 0.08V, etc. The set threshold can also be a smaller value set based on the voltage value in the reference electrical parameter, for example, the set threshold can be one-tenth, one-twelfth, one-seventeenth, etc. of the voltage value in the reference electrical parameter.

[0090] In the above steps, the number of photovoltaic branches connected to the detection system can be detected to avoid misjudgment caused by non-connection; in addition, reference electrical parameters can be determined based on the number of connected photovoltaic branches, which can make the determined reference values ​​more valuable, thereby more accurately determining whether there is a circuit abnormality in the photovoltaic array.

[0091] In the case where the photovoltaic array is electrically connected to the photovoltaic array detection system, the photovoltaic array may be in a power supply state for the photovoltaic array detection system, or the power module in the photovoltaic array detection system may be in a second power supply state for the photovoltaic array.

[0092] In one embodiment, the test electrical parameters input by the photovoltaic array to the photovoltaic array detection system may be monitored while the photovoltaic array is supplying power to the photovoltaic array detection system.

[0093] On this basis, the above-mentioned reference electrical parameters are also the theoretical electrical parameters of the photovoltaic array in the power supply state.

[0094] The test electrical parameters monitored when the photovoltaic array is powering the photovoltaic array detection system can be compared with the theoretical electrical parameters of the photovoltaic array when it is powered to determine the detection result of the photovoltaic array when the photovoltaic array is powering the photovoltaic array detection system.

[0095] By using the photovoltaic array as a power supply device, the power supply status of the photovoltaic array can be detected, and whether the power supply of the photovoltaic array is normal can be determined. Through this detection, the factory-produced photovoltaic array can provide better work.

[0096] When considering a photovoltaic array as a power supply device, the photovoltaic array not only has photocurrent, but also has the influence of some components within the photovoltaic array itself on the current. Therefore, in order to determine a more accurate reference current, when determining the reference current, it is possible to consider not only the photocurrent but also the internal components of the photovoltaic branch itself. Based on this, the reference electrical parameters include a first reference current, the electrical parameters of the photovoltaic branch include the first reference current of the photovoltaic branch, and the test electrical parameters include the first test current. As shown in Figure 3, step 320 may include steps 321 to 323.

[0097] Step 321 : determining a reference current of a single photovoltaic branch of the photovoltaic array according to characteristic parameters of the single photovoltaic branch.

[0098] Optionally, the reference current of the single photovoltaic branch may be pre-stored data. When the reference current needs to be calculated, the reference current of the single photovoltaic branch may be obtained according to the identifier of the photovoltaic array currently being tested.

[0099] The reference currents of the PV branches in different PV arrays can be different or the same. Therefore, the reference currents of the PV branches of different PV arrays can be pre-stored. For example, the identification of each PV array can be associated with the reference current of the PV branches of the PV array. Based on this, the reference current of the PV branch can be found from the pre-stored data based on the identification of the PV array currently being tested.

[0100] Optionally, step 321 may also include: determining a first initial current of the photovoltaic branch according to characteristic parameters of a single photovoltaic branch under multiple working states; and determining a reference current of the photovoltaic branch according to the first initial current under multiple working states.

[0101] The multiple operating states may include: the photovoltaic array being powered, the photovoltaic array being powered and exposed to different levels of sunlight, the photovoltaic array being operated at different time points, etc. For example, the different time points may be noon when sunlight is strongest, morning when sunlight is relatively weak, or a time point before 4 p.m. when sunlight is relatively strong.

[0102] For example, the first initial current of the photovoltaic branch may be determined according to characteristic parameters of the photovoltaic branch under the working status of the photovoltaic array at different time points.

[0103] The characteristic parameters of the photovoltaic branch may include the current that can be generated by the solar panels of the photovoltaic array, and the current of the internal components of each photovoltaic branch of the photovoltaic array.

[0104] Exemplarily, the characteristic parameters include the photocurrent and the loss current of the photovoltaic branch.

[0105] Optionally, the above-mentioned determination of the first initial current of the photovoltaic branch based on the characteristic parameters of the single photovoltaic branch may include: obtaining the photocurrent generated by the single photovoltaic branch; obtaining the loss current of the single photovoltaic branch; and determining the first initial current of the photovoltaic branch based on the photocurrent and the loss current.

[0106] As shown in Figure 4, which shows an equivalent circuit diagram of a photovoltaic branch, the equivalent circuit includes: a solar panel Sp, a diode D connected in parallel with the solar panel Sp, an equivalent parallel load Rsh, and an equivalent series load Rs.

[0107] The first initial current is the output current of the photovoltaic branch, which can be calculated using the following formula:

[0108] Ipv=Iph-Id-Ish=Iph-Ipvo{exp[q(Vpv+Ipv*Rs) / AKT]}-(Vpv+Ipv*Rs) / Rsh;

[0109] Wherein, Ipv represents the output current of the photovoltaic branch at any time; Iph represents the photocurrent generated by the solar panel of the photovoltaic branch; Id represents the current flowing through the diode D, Ish represents the current flowing through the internal equivalent parallel load; Ipvo represents the second saturation current, Vpv represents the open-circuit voltage of the photovoltaic branch, A represents the diode factor, K represents the Boltzmann constant, and T represents the absolute temperature.

[0110] In different working states, for example, under different illumination conditions, the photocurrent generated by the solar panels of the photovoltaic branch may be different, resulting in different output currents Ipv of the photovoltaic branch.

[0111] Of course, FIG4 is only an exemplary equivalent circuit, and it may include more load elements depending on the actual photovoltaic branch.

[0112] Optionally, a current corresponding to a photovoltaic branch power greater than a set power may be selected from the first initial currents under multiple working states as a reference current of the photovoltaic branch.

[0113] The aforementioned set power may be a value less than the maximum power of the photovoltaic branch. For example, the set power may be equal to 90 percent, 85 percent, or the like of the maximum power. If only one of the multiple first initial currents has a power greater than the set power, then that first initial current is used as the reference current for the photovoltaic branch. If multiple first initial currents have a power greater than the set power, then one of the multiple first initial currents may be randomly selected as the first reference current, or the average of the multiple first initial currents may be used as the first reference current.

[0114] Optionally, the first reference current may be the current at the maximum power point of the photovoltaic branch. Exemplarily, the power values ​​corresponding to the first initial current in each working state may be calculated, and the first initial current corresponding to the maximum power value may be selected as the reference current of the photovoltaic branch.

[0115] Step 322 : Determine a first reference current of the photovoltaic array according to the number of photovoltaic branches and the reference currents of the photovoltaic branches.

[0116] Exemplarily, the number of the photovoltaic branches and the reference current of the photovoltaic branches may be multiplied to obtain the first reference current of the photovoltaic array.

[0117] In this embodiment, the above step 340 may be implemented as follows: comparing the first test current with the first reference current; if the difference between the first test current and the first reference current is greater than a first current threshold, determining that an abnormality exists in the photovoltaic array.

[0118] The first test current is a current value input from the photovoltaic array to the photovoltaic array detection system, which is monitored when the photovoltaic array is supplying power to the photovoltaic array detection system.

[0119] The first current threshold is a value set as needed. For example, the first current threshold can be a threshold determined based on the first reference current. For example, the first current threshold can be one-tenth of the first reference current, one-eighth of the first reference current, one-twelfth of the first reference current, one-fifteenth of the first reference current, etc. Of course, the first current threshold can also be set to a smaller value as needed instead of the first reference current. For example, the first current threshold can be 0.1A, 1A, 1.5A, 2A, etc.

[0120] By including the number of photovoltaic branches effectively connected to the photovoltaic array in the calculation when determining the reference current, the calculated first reference current can be made more accurate, thereby also making the results of photovoltaic array detection more accurate. Furthermore, when determining the first reference current, taking into account the loss current in the photovoltaic array can also make the determined first reference current more accurate, and further, the results of photovoltaic array detection can also be made more accurate.

[0121] In order to make the test result of the photovoltaic array more comprehensive and accurate, the reference electrical parameter includes a first reference voltage, and the test electrical parameter includes a first test voltage.

[0122] The first test voltage may be a voltage value input from the photovoltaic array to the photovoltaic array detection system, which is monitored when the photovoltaic array is supplying power to the photovoltaic array detection system.

[0123] Exemplarily, step 340 may include: comparing the first test voltage with the first reference voltage, and if the difference between the first test voltage and the first reference voltage is greater than a first voltage threshold, determining that an abnormality exists in the photovoltaic array.

[0124] In the example shown in FIG. 4 , the first reference voltage can be determined from open-circuit voltages Vpv in a plurality of working states.

[0125] For example, the first reference voltage can calculate the power in each working state based on the open circuit voltage Vpv determined in multiple working states and the output current Ipv of the photovoltaic branch, and select the open circuit voltage Vpv corresponding to the maximum power value as the first reference voltage of the photovoltaic branch.

[0126] The first voltage threshold can be set to a smaller value as needed. For example, the first voltage threshold can be a threshold value determined based on the first reference voltage. For example, the first voltage threshold can be one-tenth of the first reference voltage, one-eighth of the first reference voltage, one-twelfth of the first reference voltage, one-fifteenth of the first reference voltage, etc. Of course, the first voltage threshold can also be set to a smaller value as needed instead of the first reference voltage. For example, the first voltage threshold can be 0.5V, 0.8V, 0.9V, etc.

[0127] By testing the voltage of the photovoltaic array, the test results of the photovoltaic array can be made more comprehensive, and the performance of the photovoltaic array leaving the factory can be made more reliable.

[0128] In one embodiment, the test electrical parameters of the photovoltaic array may be monitored while the power module of the photovoltaic array detection system is supplying power to the photovoltaic array.

[0129] On this basis, the above-mentioned reference electrical parameters are also the theoretical electrical parameters of the photovoltaic array in the powered state. In this state, the solar panels of the photovoltaic array do not generate photocurrent.

[0130] The test electrical parameters monitored when the power module of the photovoltaic array detection system is powering the photovoltaic array can be compared with the theoretical electrical parameters when the photovoltaic array is not powered, so as to determine the detection result of the photovoltaic array when the photovoltaic array is powering the photovoltaic array detection system.

[0131] By setting the photovoltaic array in a non-powered state, the photovoltaic array as a load can be detected, and whether the load of the photovoltaic array is stable can be determined. This detection can enable the factory-produced photovoltaic array to provide better performance.

[0132] When the PV array is used only as a load, not as a power supply, there is no photocurrent generated by the PV array. Therefore, to determine a more accurate reference current, the reference current can be determined without considering the photocurrent, but only the internal components of the PV branch itself. The reference electrical parameter includes a second reference current, and the test electrical parameter includes a second test current. As shown in FIG5 , step 320 may include steps 324 through 326.

[0133] Step 324: Obtain the load current of all load elements in a single photovoltaic branch.

[0134] Exemplarily, the load currents of all load elements of the photovoltaic branch may be obtained.

[0135] As shown in Figure 6, which shows an equivalent circuit diagram of a photovoltaic branch powered by a second power supply, in the example shown in Figure 6, the current direction of the equivalent series load Rs is opposite to that of the equivalent series load Rs in the example shown in Figure 4, and the solar panel Sp does not generate photocurrent.

[0136] Step 325 : Determine a second reference current of the photovoltaic branch according to the load currents of all the load elements.

[0137] Exemplarily, the second reference current of the photovoltaic branch may be equal to the sum of the load currents.

[0138] As shown in FIG6 , the second reference current of the photovoltaic branch may be equal to Ipv=Id+Ish;

[0139] Where Ipv represents the output current of the photovoltaic branch at any time; Id represents the current flowing through the diode D; and Ish represents the current flowing through the internal equivalent parallel load.

[0140] Step 326 : Determine a second reference current of the photovoltaic array according to the number of the photovoltaic branches and the second reference current of the photovoltaic branches.

[0141] Exemplarily, the second reference current of the photovoltaic array may be obtained by multiplying the number of the photovoltaic branches by the second reference current of the photovoltaic branches.

[0142] Optionally, a second reference current for a photovoltaic branch may be pre-stored. When the second reference current for a photovoltaic array needs to be calculated, the second reference current for the photovoltaic branch may be obtained from the pre-stored file. For example, the second reference current for the photovoltaic branch may be stored in association with an identifier of the photovoltaic array. When the second reference current for the photovoltaic branch needs to be obtained, the second reference current for the photovoltaic branch may be found in the pre-stored file based on the identifier of the photovoltaic array.

[0143] In this embodiment, the above step 340 may be implemented as follows: comparing the second test current with the second reference current; if the difference between the second test current and the second reference current is greater than a second current threshold, determining that an abnormality exists in the photovoltaic array.

[0144] The second test current is the current value of the photovoltaic array when the photovoltaic array is not powered.

[0145] The second current threshold may be the same as the first current threshold described above, or may be different from the first current threshold. For example, the second current threshold may be a threshold value determined based on the second reference current. For example, the second current threshold may be one-tenth of the second reference current, one-eighth of the second reference current, one-twelfth of the second reference current, one-fifteenth of the second reference current, etc. Of course, the second current threshold may also be set to a smaller value as needed instead of the second reference current. For example, the second current threshold may be 0.8A, 1A, 1.5A, etc.

[0146] In order to make the test result of the photovoltaic array more comprehensive and accurate, the reference electrical parameter includes a second reference voltage, and the test electrical parameter includes a second test voltage.

[0147] The second test voltage may be a voltage value output by the photovoltaic array monitored when the photovoltaic array is not used as a power supply device.

[0148] Exemplarily, step 340 may include: comparing the second test voltage with the second reference voltage, and if the difference between the second test voltage and the second reference voltage is greater than a second voltage threshold, determining that an abnormality exists in the photovoltaic array.

[0149] The second voltage threshold may be the same as the first voltage threshold described above, or may be different from the first voltage threshold described above. Of course, the second voltage threshold may be set to a smaller value as needed. For example, the second voltage threshold may be a threshold value determined based on the first reference voltage. For example, the second voltage threshold may be one-tenth of the first reference voltage, one-eighth of the first reference voltage, one-twelfth of the first reference voltage, one-fifteenth of the first reference voltage, and the like. Of course, the second voltage threshold may also be set to a smaller value as needed instead of the first reference voltage. For example, the second voltage threshold may be 0.5V, 0.3V, 0.4V, and the like.

[0150] By testing the photovoltaic array in multiple dimensions, the test results can be made more reliable, and the reliability of the photovoltaic array that has passed the test can be improved.

[0151] Through steps 310 to 340 above, the current and voltage of the confirmed effectively connected photovoltaic array can be tested to determine whether the lack of input is due to damage or an open circuit. Therefore, the method provided in this embodiment can also include: comparing the number of connected photovoltaic branches with the total number of photovoltaic branches included in the photovoltaic array to determine whether the number of connected photovoltaic branches is less than the total number of photovoltaic branches included in the photovoltaic array.

[0152] If the number of connected photovoltaic branches is less than the total number of photovoltaic branches of the photovoltaic array, it is determined that there is a connection abnormality in the photovoltaic array.

[0153] For example, if the photovoltaic array includes a total of N photovoltaic branches, and the number of currently connected branches is N, but the number of detected photovoltaic branches is M, and M is less than N, it means that there are some invalid connections, and it can be determined that there is an access abnormality in the photovoltaic array.

[0154] Through the method of the embodiment of the present application, it is possible to combine the detection of the number of effectively connected photovoltaic branches and the linkage judgment of the voltage and current signals of the connected photovoltaic branches to identify abnormal conditions of the photovoltaic array, and to more accurately locate the type of abnormality in the photovoltaic array.

[0155] The foregoing description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included within the scope of protection of the present application. It should be noted that similar reference numerals and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined or explained in subsequent figures.

[0156] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A photovoltaic array detection method, characterized in that: Applied to a photovoltaic array detection system, the photovoltaic array detection method includes: Obtain the number of photovoltaic branches connected to the photovoltaic array; Determining reference electrical parameters according to the number of the photovoltaic branches and the electrical parameters of the photovoltaic branches; When the photovoltaic array is electrically connected to the photovoltaic array detection system, obtaining test electrical parameters of the photovoltaic array; A detection result of the photovoltaic array is determined according to the test electrical parameter and the reference electrical parameter.

2. The method according to claim 1, characterized in that The step of obtaining test electrical parameters of the photovoltaic array when the photovoltaic array is electrically connected to the photovoltaic array detection system includes: When the photovoltaic array is supplying power to the photovoltaic array detection system, the test electrical parameters input by the photovoltaic array to the photovoltaic array detection system are monitored.

3. The method according to claim 2, characterized in that The reference electrical parameter includes a first reference current, the electrical parameter of the photovoltaic branch includes the first reference current of the photovoltaic branch, and the test electrical parameter includes a first test current; The determining of reference electrical parameters according to the number of the photovoltaic branches and the electrical parameters of the photovoltaic branches includes: determining a reference current of a single photovoltaic branch of the photovoltaic array according to characteristic parameters of the single photovoltaic branch; determining a first reference current of the photovoltaic array according to the number of the photovoltaic branches and the reference currents of the photovoltaic branches; The determining of the detection result of the photovoltaic array according to the test electrical parameter and the reference electrical parameter includes: The first test current is compared with the first reference current. If a difference between the first test current and the first reference current is greater than a first current threshold, it is determined that an abnormality exists in the photovoltaic array.

4. The method according to claim 3, characterized in that The step of determining a reference current of a single photovoltaic branch of the photovoltaic array according to electrical parameters of the single photovoltaic branch includes: determining a first initial current of the photovoltaic branch according to characteristic parameters of the single photovoltaic branch under multiple working states; A reference current of the photovoltaic branch is determined according to the first initial current under multiple working states.

5. The method according to claim 4, characterized in that The characteristic parameters include the photocurrent and loss current of the photovoltaic branch; The determining, based on characteristic parameters of the single photovoltaic branch, a first initial current of the photovoltaic branch includes: Obtaining the photocurrent generated by the single photovoltaic branch; Obtaining the loss current of a single photovoltaic branch; A first initial current of the photovoltaic branch is determined according to the photogenerated current and the loss current.

6. The method according to claim 5, characterized in that The determining of the reference current of the photovoltaic branch according to the first initial current in a plurality of working states includes: A current corresponding to a photovoltaic branch power greater than a set power is selected from the first initial currents under multiple working states as a reference current of the photovoltaic branch.

7. The method according to claim 2, characterized in that The reference electrical parameter includes a first reference voltage, and the test electrical parameter includes a first test voltage; The determining of the detection result of the photovoltaic array according to the test electrical parameter and the reference electrical parameter includes: The first test voltage is compared with the first reference voltage. If the difference between the first test voltage and the first reference voltage is greater than a first voltage threshold, it is determined that an abnormality exists in the photovoltaic array.

8. The method according to claim 1, characterized in that The photovoltaic array detection system includes: a power supply module; The step of obtaining test electrical parameters of the photovoltaic array when the photovoltaic array is electrically connected to the photovoltaic array detection system includes: When the power module of the photovoltaic array detection system is supplying power to the photovoltaic array, test electrical parameters of the photovoltaic array are obtained.

9. The method according to claim 8, characterized in that The reference electrical parameter includes a second reference current, the electrical parameter of the photovoltaic branch includes the second reference current of the photovoltaic branch, and the test electrical parameter includes a second test current; The determining of reference electrical parameters according to the number of the photovoltaic branches and the electrical parameters of the photovoltaic branches includes: Obtaining the load current of all load elements in a single photovoltaic branch; determining a second reference current of the photovoltaic branch according to the load currents of all the load elements; determining a second reference current of the photovoltaic array according to the number of the photovoltaic branches and the second reference currents of the photovoltaic branches; The determining of the detection result of the photovoltaic array according to the test electrical parameter and the reference electrical parameter includes: The second test current is compared with the second reference current. If the difference between the second test current and the second reference current is greater than a second current threshold, it is determined that an abnormality exists in the photovoltaic array.

10. The method according to claim 8, characterized in that The reference electrical parameter includes a second reference voltage, and the test electrical parameter includes a second test voltage; The determining of the detection result of the photovoltaic array according to the test electrical parameter and the reference electrical parameter includes: The second test voltage is compared with the second reference voltage. If the difference between the second test voltage and the second reference voltage is greater than a second voltage threshold, it is determined that an abnormality exists in the photovoltaic array.

11. The method according to any one of claims 1 to 10, characterized in that: The method further comprises: Comparing the number of the connected photovoltaic branches with the total number of photovoltaic branches included in the photovoltaic array to determine whether the number of the connected photovoltaic branches is less than the total number of photovoltaic branches included in the photovoltaic array; If the number of the connected photovoltaic branches is less than the total number of photovoltaic branches included in the photovoltaic array, it is determined that there is an access abnormality in the photovoltaic array.

12. A photovoltaic array detection system, characterized in that: include: Solar energy storage inverter; The solar-storage inverter includes: an input interface, a converter and a central controller; The input interface is used to connect to the photovoltaic array; The converter is used to detect the electrical parameters of the photovoltaic array; When the solar-storage inverter is in operation, the steps of the method according to any one of claims 1 to 10 are performed.

13. The photovoltaic array detection system according to claim 12, characterized in that: Also includes: A power module connected to the photovoltaic inverter; The power supply module is used to provide a second power supply to the photovoltaic array.

Images