Safety management system and safety management method for photovoltaic module

Abstract

The invention discloses a safety management system and a safety management method for a photovoltaic module. The safety management system comprises a plurality of photovoltaic group strings which supply power to a bus; the photovoltaic group string comprises a plurality of photovoltaic modules and a plurality of module-level power electronic modules, and at least one photovoltaic module is correspondingly and electrically connected with the module-level power electronic modules; wherein the component-level power electronic module comprises a positive electrode output end, a negative electrode output end and a fault detection circuit; the component-level power electronic modules in the same photovoltaic group string are connected in series through the positive electrode output end and the negative electrode output end; and the fault detection circuits of the component-level power electronic modules in the same photovoltaic group string are electrically connected with a common connecting line. According to the invention, accurate positioning of the fault point in the photovoltaic string is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation, and in particular to a safety management system and a safety management method for photovoltaic modules. Background Art

[0002] With the continuous implementation of the concept of green development and environmental protection, the continuous development of new energy power facilities has been promoted. As a green and pollution-free power source, photovoltaic power generation is becoming more and more popular, and the requirements for the safety of photovoltaic power generation are also increasing. As an important core component of a photovoltaic power generation system, the reliability of photovoltaic modules directly affects the overall performance of the power generation system. However, in fact, photovoltaic modules are subject to many restrictive factors, and the characteristic differences of each photovoltaic module itself will cause loss of connection and combination efficiency. Photovoltaic module arrays are generally in series-parallel connection. If a fault occurs in the circuit, all other components with series-parallel relationships may be affected due to the decrease in voltage and current intensity. To ensure the safety and reliability of the operation of the photovoltaic array, it is particularly important to give full play to the maximum power generation efficiency of each photovoltaic module and ensure that the photovoltaic module is in a normal working state.

[0003] Judging the fault location in the circuit is a rather difficult problem in the photovoltaic system. Parallel faults or grounding faults in the photovoltaic system may cause arcs or may not cause arcs but only leakage. The location where such faults occur may also be between the line and the ground, or between lines, etc. In the prior art, there is no corresponding detection means to detect the exact location of the fault. Summary of the Invention

[0004] The present invention provides a safety management system and a safety management method for photovoltaic modules to solve the problem that the fault point cannot be accurately detected in a photovoltaic string.

[0005] According to one aspect of the present invention, a safety management system for photovoltaic modules is provided, which is characterized by including:

[0006] A plurality of photovoltaic strings, and the plurality of photovoltaic strings supply power to a bus; the photovoltaic string includes a plurality of photovoltaic modules and a plurality of component-level power electronic modules, and at least one of the photovoltaic modules is electrically connected to the component-level power electronic module correspondingly;

[0007] Wherein, the component-level power electronic module includes: a positive output terminal, a negative output terminal and a fault detection circuit; the component-level power electronic modules in the same photovoltaic string are connected in series through the positive output terminal and the negative output terminal; the fault detection circuits of the component-level power electronic modules in the same photovoltaic string are all electrically connected to a common connection line.

[0008] Optionally, the fault detection circuit includes an intermediate connection terminal; the intermediate connection terminals of the component-level power electronic modules in the same photovoltaic string are all connected to a common connection line.

[0009] Optionally, the intermediate connection terminal of the component-level power electronic module is electrically connected or not electrically connected to a circuit node in the component-level power electronic module.

[0010] Optionally, the fault detection circuit includes a first current terminal and a second current terminal, and the first current terminal and the second current terminal are electrically connected; the common connection line of the photovoltaic string sequentially passes through the first current terminal and the second current terminal of each component-level power electronic module.

[0011] Optionally, the component-level power electronic module is a switch-off device or an optimizer.

[0012] According to another aspect of the present invention, there is also provided a safety management method for a photovoltaic module, including:

[0013] A plurality of photovoltaic strings supply power to a busbar;

[0014] A plurality of photovoltaic modules in each photovoltaic string are connected in series through correspondingly provided component-level power electronic modules; wherein, the fault detection circuit of the component-level power electronic module is electrically connected to the common connection line;

[0015] Detect the electrical parameter relationship between the positive output terminal, the negative output terminal and the fault detection circuit of each component-level power electronic module, and judge the line fault.

[0016] Optionally, the method for judging the line fault specifically includes:

[0017] If the closed loop formed by the positive output terminal, the negative output terminal and the fault detection circuit of two adjacent component-level power electronic modules does not satisfy Kirchhoff's law, there is a fault in the line.

[0018] Optionally, the fault detection circuit includes an intermediate connection terminal; the intermediate connection terminals of the component-level power electronic modules in the same photovoltaic string are all connected to the common connection line; the method for judging the line fault specifically includes:

[0019] The positive output terminal of the first component-level power electronic module is electrically connected to the negative output terminal of the second component-level power electronic module;

[0020] Detect the voltage difference V1 between the intermediate connection terminal and the positive output terminal of the first component-level power electronic module, and detect the voltage difference V2 between the negative output terminal and the intermediate connection terminal of the second component-level power electronic module;

[0021] If the sum of the voltage differences V1 and V2 exceeds the normal set range, there is a fault in the circuit.

[0022] Optionally, the fault detection circuit includes an intermediate connection terminal; the intermediate connection terminals of the component-level power electronic modules in the same photovoltaic string are all connected to a common connection line; the method for judging a circuit fault specifically includes:

[0023] Detect the electrical parameter fluctuation between the intermediate connection terminal of the component-level power electronic module and the positive output terminal;

[0024] If the electrical parameter fluctuation exceeds the normal set range, there is a fault in the circuit.

[0025] Optionally, the fault detection circuit includes an intermediate connection terminal; the intermediate connection terminals of the component-level power electronic modules in the same photovoltaic string are all connected to a common connection line; the method for judging a circuit fault specifically includes:

[0026] Detect the electrical parameter fluctuation between the intermediate connection terminal of the component-level power electronic module and the negative output terminal;

[0027] If the electrical parameter fluctuation exceeds the normal set range, there is a fault in the circuit.

[0028] Optionally, the fault detection circuit includes a first current terminal and a second current terminal, and the first current terminal and the second current terminal are electrically connected; the common connection line of the photovoltaic string sequentially passes through the first current terminal and the second current terminal of each component-level power electronic module; the method for judging a circuit fault specifically includes:

[0029] The positive output terminal of the first component-level power electronic module is electrically connected to the negative output terminal of the second component-level power electronic module;

[0030] The second current terminal of the first component-level power electronic module is electrically connected to the first current terminal of the second component-level power electronic module;

[0031] Detect the voltage difference V1 between the current terminal of the first component-level power electronic module and the positive output terminal, and detect the voltage difference V2 between the negative output terminal of the second component-level power electronic module and the current terminal; wherein, the current terminal is the first current terminal or the second current terminal;

[0032] If the sum of the voltage differences V1 and V2 exceeds the normal set range, there is a fault in the circuit.

[0033] Optionally, the voltage difference V1 and / or the voltage difference V2 is measured by a voltage detection device.

[0034] Optionally, the voltage difference V1 and / or the voltage difference V2 are derived and calculated in an equivalent manner.

[0035] Optionally, after it is determined that there is a fault in the line, it further includes:

[0036] Based on the sum of the voltage difference V1 and the voltage difference V2 at each position in the photovoltaic string, determine the location where the fault occurs;

[0037] Among them, the fault occurs at the position where the sum of the voltage difference V1 and the voltage difference V2 is the largest.

[0038] Optionally, at least one of the component-level power electronic modules is also connected in series between the first component-level power electronic module and the second component-level power electronic module.

[0039] Optionally, the voltage values detected by the component-level power electronic modules are propagated to each other through communication;

[0040] The method for judging line faults is executed in the component-level power electronic module; or, the method for judging line faults is executed in a central controller that communicates with the component-level power electronic module.

[0041] Optionally, the fault detection circuit includes a first current terminal and a second current terminal, and the first current terminal and the second current terminal are electrically connected; the common connection line of the photovoltaic string sequentially passes through the first current terminal and the second current terminal of each of the component-level power electronic modules; the method for judging line faults specifically includes:

[0042] Detect the electrical parameter fluctuations between the current terminal and the output terminal of the component-level power electronic module; among them, the current terminal is the first current terminal or the second current terminal; the output terminal is the positive output terminal or the negative output terminal;

[0043] If the electrical parameter fluctuations exceed the normal set range, there is a fault in the line.

[0044] Optionally, the electrical parameters include at least one of the following: the magnitude of the voltage, the magnitude of the set frequency component of the voltage, the variation law of the voltage, the variation law of the set frequency component of the voltage, and the spectral distribution characteristics of the voltage.

[0045] Optionally, after it is determined that there is a fault in the line, it further includes:

[0046] Based on the electrical parameter fluctuations at each position in the photovoltaic string, determine the location where the fault occurs;

[0047] Among them, the fault occurs at the position where the electrical parameter fluctuations are the largest.

[0048] Optionally, the fault detection circuit includes a first current terminal and a second current terminal, and the first current terminal and the second current terminal are electrically connected; the common connection line of the photovoltaic string sequentially passes through the first current terminal and the second current terminal of each of the component-level power electronic modules; the method for determining a line fault specifically includes:

[0049] Detect the current difference between the output terminal of the component-level power electronic module and the first current terminal; the output terminal is the positive output terminal or the negative output terminal;

[0050] If the current difference exceeds the normal set range, there is a fault in the line.

[0051] Optionally, after determining that there is a fault in the line, it further includes:

[0052] Obtain the distribution of the current differences according to the current differences at each position in the photovoltaic string;

[0053] Judge the location where the fault occurs according to the distribution.

[0054] Optionally, the fault types include: disconnection, poor contact, arc, and leakage.

[0055] In the embodiment of the present invention, by adding a fault detection circuit in the component-level power electronic module and electrically connecting each fault detection circuit to the common connection line, it is beneficial to obtain the electrical parameter relationship among the positive output terminal, the negative output terminal, and the common connection line 3. On the one hand, the common connection line is the connection line of the connection bus, and the voltage thereon is relatively stable. Therefore, by detecting the voltage difference between the positive output terminal (or the negative output terminal) and the common connection line, it is equivalent to finding a reference point for the detection of each voltage difference, and the voltage detection will be more accurate. Further, in actual wiring, the component-level power electronic module is usually connected to the common connection line nearby, which is equivalent to segmenting the common connection line, facilitating the accurate positioning of the fault location. Therefore, by calculating the electrical parameters between each component-level power electronic module, the fault location can be accurately judged. In addition, in the embodiment of the present invention, when a fault occurs, it is not necessary for the maintenance personnel to conduct on-site inspections one by one to determine the fault point, reducing the workload of the maintenance personnel and shortening the power outage time.

[0056] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Description of the Drawings

[0057] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0058] Figure 1 Schematic structural diagram of a safety management system for a photovoltaic module provided as a comparative example;

[0059] Figure 2 Schematic partial structural diagram of a safety management system for a photovoltaic module provided as a comparative example;

[0060] Figure 3 Schematic structural diagram of a safety management system for a photovoltaic module provided in an embodiment of the present invention;

[0061] Figure 4 Schematic partial structural diagram of a safety management system for a photovoltaic module provided in an embodiment of the present invention;

[0062] Figure 5 Schematic structural diagram of another safety management system for a photovoltaic module provided in an embodiment of the present invention;

[0063] Figure 6 Schematic partial structural diagram of another safety management system for a photovoltaic module provided in an embodiment of the present invention;

[0064] Figure 7 Schematic structural diagram of yet another safety management system for a photovoltaic module provided in an embodiment of the present invention;

[0065] Figure 8 Schematic partial structural diagram of yet another safety management system for a photovoltaic module provided in an embodiment of the present invention;

[0066] Figure 9 Flowchart of a safety management method for a photovoltaic module provided in an embodiment of the present invention;

[0067] Figure 10 Schematic partial structural diagram of yet another safety management system for a photovoltaic module provided in an embodiment of the present invention;

[0068] Figure 11 Schematic partial structural diagram of yet another safety management system for a photovoltaic module provided in an embodiment of the present invention;

[0069] Figure 12 Schematic partial structural diagram of yet another safety management system for a photovoltaic module provided in an embodiment of the present invention;

[0070] Figure 13A partial structural schematic diagram of another photovoltaic module safety management system provided by an embodiment of the present invention;

[0071] Figure 14 A partial structural schematic diagram of another photovoltaic module safety management system provided by an embodiment of the present invention. Detailed implementation manners

[0072] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0073] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0074] In order to clearly illustrate the implementation principle and the beneficial effects achieved by the photovoltaic module safety management system provided by the embodiments of the present invention, first, the principle of the photovoltaic module safety management system and fault detection provided by the comparative example will be described.

[0075] Figure 1 A structural schematic diagram of a photovoltaic module safety management system provided by the comparative example, Figure 2 A partial structural schematic diagram of a photovoltaic module safety management system provided by the comparative example. Refer to Figure 1 and Figure 2, the photovoltaic module includes a plurality of photovoltaic strings 1, and each photovoltaic string 1 includes a plurality of photovoltaic modules 11 and module-level power electronics modules 12 corresponding to the photovoltaic modules 11 one by one. The module-level power electronics module 12 (Module Level Power Electronics, MLPE) refers to a type of power electronics device that can perform refined control of electric energy, including micro-inverters, module-level disconnectors, power optimizers, etc. Specifically, the positive voltage PV+ and negative voltage PV- of the photovoltaic module 11 are input into the module-level power electronics module 12, and the module-level power electronics module 12 can achieve module-level control of the photovoltaic module 11. Each photovoltaic module 11 is connected in series through the module-level power electronics module 12. However, when a fault occurs on the transmission line, the change in voltage or current caused by the fault will propagate along the entire line.

[0076] Exemplarily, referring to Figure 2 , when a leakage fault occurs at node A, the leakage current will propagate along the entire line of the photovoltaic string 1. At this time, the leakage current will cause a change in voltage or current on the module-level power electronics module 121, and voltage fluctuations will occur on both its positive output terminal OUT+ and negative output terminal OUT-. Similarly, the leakage current will cause a change in voltage or current on the module-level power electronics module 122, and voltage fluctuations will occur on both its positive output terminal OUT+ and negative output terminal OUT-. Due to the different distances from the fault point node A, the influence of the leakage current on the magnitudes of the positive output terminal OUT+ and negative output terminal OUT- of the module-level power electronics module 121, and the positive output terminal OUT+ and negative output terminal OUT- of the module-level power electronics module 122 may be different. However, this influence difference is sometimes very small.

[0077] A method for detecting whether a fault occurs on the photovoltaic string 1 is to judge the location of the fault by measuring the voltage difference between the positive output terminal OUT+ and negative output terminal OUT- of each module-level power electronics module 12. When it is detected that the voltage difference between the positive output terminal OUT+ and negative output terminal OUT- of a certain module-level power electronics module 12 is too large, too small, or fluctuates abnormally, it can be judged that the location of the fault is closest to this module-level power electronics module 12. However, as mentioned above, during the process of taking the difference of the voltages at the positive output terminal OUT+ and negative output terminal OUT- of the module-level power electronics module 12 after the fault occurs, the voltage change caused by the fault is eliminated, and the change in its voltage difference is very small, usually unable to detect the fault.

[0078] In view of this, the present invention provides a safety management system for a photovoltaic module. Figure 3 It is a schematic structural diagram of a safety management system for a photovoltaic module provided by an embodiment of the present invention. Figure 4This is a partial structural schematic diagram of a safety management system for a photovoltaic module provided by an embodiment of the present invention. Refer to Figure 3 and Figure 4 , the photovoltaic module includes a plurality of photovoltaic strings 2, and the plurality of photovoltaic strings 2 supply power to the bus in a parallel connection manner. The photovoltaic string 2 includes a plurality of photovoltaic modules 21 and a plurality of component-level power electronic modules 22, and the photovoltaic modules 21 are electrically connected to the component-level power electronic modules 22 in a one-to-one correspondence.

[0079] Among them, Figure 3 exemplarily shows two photovoltaic strings 2 connected in parallel, and after the parallel connection, they are connected to an inverter or a photovoltaic controller 4, which is not a limitation of the present invention. In other embodiments, a plurality of photovoltaic strings 2 can also be set to be connected in parallel, and after the parallel connection, they are connected to an inverter or a photovoltaic controller 4; one photovoltaic string 2 can also be set to be connected to an inverter or a photovoltaic controller 4, and it can be set according to needs in actual applications.

[0080] Among them, Figure 3 and Figure 4 exemplarily shows that the photovoltaic modules 21 are electrically connected to the component-level power electronic modules 22 in a one-to-one correspondence, which is not a limitation of the present invention. In other embodiments, one component-level power electronic module 22 may also be connected to two photovoltaic modules 21, or one component-level power electronic module 22 may also be connected to a plurality of photovoltaic modules 21. Exemplarily, the relationship between the component-level power electronic module 22 and the photovoltaic module 21 is one-to-one, one-to-two, one-to-four, or one-to-eight, etc. Among them, the component-level power electronic module 22 includes: a positive output terminal OUT+, a negative output terminal OUT-, and a fault detection circuit 202; the photovoltaic modules 21 in the same photovoltaic string are connected in series through the positive output terminal OUT+ and the negative output terminal OUT- of the component-level power electronic module 22; the fault detection circuits 202 of the component-level power electronic modules 22 in the same photovoltaic string are all electrically connected to the common connection line 3.

[0081] Among them, the component-level power electronic module 22 can be used to control the photovoltaic module 21. For example, it can cut off the connection with the access photovoltaic module 21. Exemplarily, when a fault occurs in the photovoltaic module 21, the component-level power electronic module 22 can quickly cut off the photovoltaic module 21 to prevent the fault current from being input into the bus. Exemplarily, the specific way that the photovoltaic modules 21 in the same photovoltaic string are connected in series through the positive output terminal OUT+ and the negative output terminal OUT- of the component-level power electronic module 22 is: the positive output terminal PV+ and the negative output terminal PV- of each photovoltaic module 21 are electrically connected to the corresponding component-level power electronic module 22.

[0082] Among them, when the relationship between the component-level power electronic module 22 and the photovoltaic module 21 is one-to-one, the positive output terminal PV+ and the negative output terminal PV- of the photovoltaic module 21 are respectively electrically connected to the corresponding ports on the component-level power electronic module 22. When the relationship between the component-level power electronic module 22 and the photovoltaic module 21 is one-to-many, multiple sets of ports can be provided on the component-level power electronic module 22, and the positive output terminal PV+ and the negative output terminal PV- of each photovoltaic module 21 are respectively electrically connected to the corresponding ports on the component-level power electronic module 22; a set of ports can also be provided on the component-level power electronic module 22, and after the photovoltaic modules 21 are connected in series, they are electrically connected to this set of ports; at least two sets of ports can also be provided on the component-level power electronic module 22 to achieve the combination of the above two.

[0083] Specifically, the positive output terminal OUT+ of the component-level power electronic module 22 is electrically connected to the negative output terminal OUT- of the adjacent component-level power electronic module 22 on the right; the positive output terminal OUT+ of the component-level power electronic module 22 is electrically connected to the negative output terminal OUT- of the adjacent component-level power electronic module 22 on the right, and so on. The positive output terminal OUT+ of the rightmost component-level power electronic module 22 is connected to the positive bus, and the negative output terminal OUT- of the leftmost component-level power electronic module 22 is connected to the negative bus. The negative output terminal OUT- of the leftmost component-level power electronic module 22 is the farthest from the negative bus, and the connecting line between this negative output terminal OUT- and the negative bus is the common connecting line 3. In other embodiments, it is also possible to set the positive output terminal OUT+ of the component-level power electronic module 22 that is far from the bus to be connected to the positive bus through a connecting line. At this time, the connecting line between this positive output terminal OUT+ and the positive bus is the common connecting line 3.

[0084] Based on the above embodiments, optionally, the component-level power electronic module 22 is a disconnector or an optimizer.

[0085] Among them, the optimizer is a device that can implement the maximum power point tracking function and the fast shutdown function. By connecting to the photovoltaic module 21, the optimizer adopts the predicted current and voltage technology to ensure that the photovoltaic module 21 is always in the optimal working state, so as to solve the influence of the photovoltaic power station on the power generation due to shadow occlusion, inconsistent orientation, or component electrical specification differences. In addition, the optimizer also has the function of shutting down the photovoltaic module 21. In case of an emergency, it will automatically cut off the connection between the photovoltaic modules 21. The disconnector is a device that can quickly shut down the photovoltaic module 21. In a critical situation, through this device, the connection between each photovoltaic module 21 can be quickly shut down remotely or manually, so as to eliminate the DC high voltage existing in the photovoltaic system array, reduce the electric shock risk, solve the rescue risk, and ensure the safe operation of each photovoltaic module 21.

[0086] In the embodiment of the present invention, by adding a fault detection circuit 202 in the component-level power electronic module 22 and electrically connecting each fault detection circuit 202 to the common connection line 3, it is beneficial to obtain the electrical parameter relationship among the positive output terminal OUT+, the negative output terminal OUT-, and the common connection line 3. On the one hand, the common connection line 3 is a connection line connecting the busbars, and the voltage thereon is relatively stable. Therefore, by detecting the voltage difference between the positive output terminal OUT+ (or the negative output terminal OUT-) and the common connection line 3, it is equivalent to finding a reference point for the detection of each voltage difference, and the voltage detection will be more accurate. Further, in actual wiring, the component-level power electronic module 22 is usually connected to the common connection line 3 nearby, which is equivalent to segmenting the common connection line 3, facilitating the accurate positioning of the fault occurrence location. Therefore, by calculating the electrical parameters among the component-level power electronic modules 22, the fault location can be accurately determined. In addition, in the embodiment of the present invention, when a fault occurs, it is not necessary for the maintenance personnel to conduct on-site inspections one by one to determine the fault point, reducing the workload of the maintenance personnel and shortening the power outage time.

[0087] In the above embodiments, there are various ways to set the fault detection circuit 202. Several of them will be described below, but it is not a limitation to the present invention.

[0088] Figure 5 FIG. is a schematic structural diagram of another safety management system for photovoltaic modules provided by the embodiment of the present invention. Figure 6 FIG. is a partial structural diagram of another safety management system for photovoltaic modules provided by the embodiment of the present invention. Refer to Figure 5 and Figure 6 , in an embodiment of the present invention, optionally, the fault detection circuit 202 includes an intermediate connection end STR, and the intermediate connection ends STR of the component-level power electronic modules 22 in the same photovoltaic string are all connected to the common connection line 3. With this setting, the circuit structure is simple and easy to implement.

[0089] Based on the above embodiments, optionally, the intermediate connection end STR of the fault detection circuit 202 is electrically connected or not electrically connected to the circuit node in the component-level power electronic module 22.

[0090] Among them, when the intermediate connection end STR of the fault detection circuit 202 is not electrically connected to the circuit node in the component-level power electronic module 22, the intermediate connection end STR is only used to receive the electrical parameter signal at the position corresponding to the component-level power electronic module 22 on the common connection line 3. In some embodiments, the intermediate connection end STR of the fault detection circuit 202 can also be electrically connected to the circuit node in the component-level power electronic module 22, and this circuit node should be a node equipotential with the common connection line 3.

[0091] Based on the above embodiments, optionally, the component-level power electronic module 22 can be used to detect at least one of the voltage between the positive output terminal OUT+ and the intermediate connection terminal STR, the voltage between the negative output terminal OUT- and the intermediate connection terminal STR, and the voltage between the positive output terminal OUT+ and the negative output terminal OUT-.

[0092] When a fault occurs on the line, the embodiment of the present invention can analyze and judge the voltage values between the component-level power electronic modules 22 by the voltage differences between the positive output terminal OUT+ and the intermediate connection terminal STR and between the negative output terminal OUT- and the intermediate connection terminal STR, so as to obtain the abnormal voltage conditions between the component-level power electronic modules 22, and thus accurately determine the location of the fault point.

[0093] Figure 7 It is a schematic structural diagram of another safety management system for photovoltaic modules provided by the embodiment of the present invention. Figure 8 It is a partial structural schematic diagram of another safety management system for photovoltaic modules provided by the embodiment of the present invention. Refer to Figure 7 And Figure 8 , in an embodiment of the present invention, optionally, the fault detection circuit 202 includes a first current terminal S1 and a second current terminal S2, and the common connection line 3 of the photovoltaic string 21 sequentially passes through the first current terminal S1 and the second current terminal S2 of each component-level power electronic module. That is, the first current terminal S1 and the second current terminal S2 in the fault detection circuit 202 are electrically connected, and the first current terminal S1 and the second current terminal S2 are connected in series in the common connection line 3. The embodiment of the present invention is arranged in this way, and the circuit structure is simple and easy to implement.

[0094] Specifically, the negative output terminal OUT- of the leftmost component-level power electronic module 22 is connected to its own first current terminal S1 through the common connection line 3 and is connected to the first current terminal S1 of the adjacent component-level power electronic module 22 on the right through the second current terminal S2, and so on. The second current terminal S2 of the rightmost component-level power electronic module 22 is connected to the negative bus through the common connection line 3. In other embodiments, it can also be set that the positive output terminal OUT+ of the leftmost component-level power electronic module 22 is connected to its own second current terminal S2 through the common connection line 3 and is connected to the second current terminal S2 of the adjacent component-level power electronic module 22 on the right through the first current terminal S1, and so on. The first current terminal S1 of the rightmost component-level power electronic module 22 is connected to the positive bus through the common connection line 3.

[0095] Furthermore, Figure 7 The shown embodiment can be regarded as Figure 5 The subordinate solution of the shown embodiment, Figure 7The embodiments shown are more conducive to simplifying on-site wiring. The specific reasons are as follows: In Figure 5 the embodiment shown, a three-terminal connector is required when the component-level power electronic module 22 is connected to the common connection line 3; while in Figure 7 the embodiment shown, the common connection line 3 can be directly connected to the terminal of the component-level power electronic module 22, and there is no need to provide an additional three-terminal connector.

[0096] Based on the above embodiments, optionally, the component-level power electronic module 22 can be used to detect at least one of the voltage between the positive output terminal OUT+ and the second current terminal S2, the voltage between the negative output terminal OUT- and the first current terminal S1, the voltage between the positive output terminal OUT+ and the first current terminal S1, the voltage between the negative output terminal OUT- and the second current terminal S2, the voltage between the positive output terminal OUT+ and the negative output terminal OUT-, the current of the positive output terminal OUT+, the current of the second current terminal S2, the current of the negative output terminal OUT-, and the current of the first current terminal S1.

[0097] When a fault occurs on the line, the embodiment of the present invention can analyze and judge the voltage difference between the positive output terminal OUT+ and the second current terminal S2, and the voltage difference between the negative output terminal OUT- and the first current terminal S1, so as to obtain the voltage abnormality between each component-level power electronic module 22, and thus accurately determine the location of the fault point. Alternatively, the embodiment of the present invention can analyze and judge the current difference between the positive output terminal OUT+ and the second current terminal S2, or the current difference between the negative output terminal OUT- and the first current terminal S1, so as to obtain the current abnormality between each component-level power electronic module 22.

[0098] The embodiment of the present invention also provides a safety management method for a photovoltaic module, and this safety management method can be applied to the safety management system of the photovoltaic module provided by any embodiment of the present invention. Figure 9 is a flowchart of a safety management method for a photovoltaic module provided by an embodiment of the present invention. Combining Figures 3 - 9 , this safety management method includes:

[0099] S110. Multiple photovoltaic strings 2 supply power to the bus.

[0100] Optionally, multiple photovoltaic strings 2 supply power to the bus through an inverter or a photovoltaic controller 4. The inverter or the photovoltaic controller 4 can be used to convert the direct current DC generated by the multiple photovoltaic strings 2 into a set alternating current, so as to meet the grid connection requirements or the power consumption requirements of AC electrical equipment on the user side.

[0101] S120. Multiple photovoltaic modules 21 in each photovoltaic string 2 are connected in series through component-level power electronic modules 22 arranged in one-to-one correspondence. Among them, the fault detection circuit 202 of the component-level power electronic module 22 is electrically connected to the common connection line 3.

[0102] Among them, the component-level power electronic module 22 includes a positive output terminal OUT+, a negative output terminal OUT-, and a fault detection circuit 202. Exemplarily, the specific way for the photovoltaic modules 21 in the same photovoltaic string to be connected in series through the positive output terminal OUT+ and the negative output terminal OUT- of the component-level power electronic module 22 is as follows: The positive output terminal PV+ and the negative output terminal PV- of each photovoltaic module 21 are electrically connected to the corresponding component-level power electronic module 22. Specifically, the positive output terminal OUT+ of the component-level power electronic module 22 is electrically connected to the negative output terminal OUT- of the adjacent component-level power electronic module 22 on the right; the positive output terminal OUT+ of the component-level power electronic module 22 is electrically connected to the negative output terminal OUT- of the adjacent component-level power electronic module 22 on the right, and so on. The positive output terminal OUT+ of the rightmost component-level power electronic module 22 is connected to the positive bus, and the negative output terminal OUT- of the leftmost component-level power electronic module 22 is connected to the negative bus. The negative output terminal OUT- of the leftmost component-level power electronic module 22 is the farthest from the negative bus, and the connection line between this negative output terminal OUT- and the negative bus is the common connection line 3. In other embodiments, it is also possible to set the positive output terminal OUT+ of the component-level power electronic module 22 that is farther from the bus to be connected to the positive bus through a connection line. At this time, the connection line between this positive output terminal OUT+ and the positive bus is the common connection line 3.

[0103] S130. Detect the electrical parameter relationship of the positive output terminal OUT+, the negative output terminal OUT-, and the fault detection circuit 202 of each component-level power electronic module 22 to judge the line fault.

[0104] In the embodiment of the present invention, a fault detection circuit 202 is electrically connected to the common connection line 3, so that the electrical parameter relationship among the positive output terminal OUT+, the negative output terminal OUT−, and the fault detection circuit 202 includes the electrical parameter relationship of the common connection line 3. On the one hand, the common connection line 3 is a connection line connecting the busbars, and the voltage thereon is relatively stable. Therefore, by detecting the voltage difference between the positive output terminal OUT+ (or the negative output terminal OUT−) and the common connection line 3, it is equivalent to finding a reference point for the detection of each voltage difference, and the voltage detection will be more accurate. Further, in actual wiring, the component-level power electronic module 22 is usually connected to the common connection line 3 nearby, which is equivalent to segmenting the common connection line 3, facilitating the accurate positioning of the fault occurrence location. Therefore, by calculating the electrical parameters between each component-level power electronic module 22, the fault location can be accurately determined. In addition, in the embodiment of the present invention, when a fault occurs, it is not necessary for the maintenance personnel to conduct on-site inspections one by one to determine the fault point, reducing the workload of the maintenance personnel and shortening the power outage time.

[0105] Based on the above embodiments, due to the different structures of the fault detection circuit 202, its fault detection principles also differ. The following will separately describe different fault detection circuits 202, but this is not a limitation to the present invention.

[0106] Continuing to refer to Figure 5 、 Figure 6 and Figure 9 In an embodiment of the present invention, optionally, the fault detection circuit 202 includes an intermediate connection end STR, and the intermediate connection ends STR of the component-level power electronic modules 22 in the same photovoltaic string are all connected to the common connection line 3. The structure of this fault detection circuit 202 is suitable for fault detection using voltage relationships.

[0107] Exemplarily, the component-level power electronic module 22 can be used to detect at least one of the voltage between its positive output terminal OUT+ and the intermediate connection end STR, the voltage between its negative output terminal OUT− and the intermediate connection end STR, and the voltage between the positive output terminal OUT+ and the negative output terminal OUT−. When a fault occurs on the line, in the embodiment of the present invention, by analyzing the voltage differences between the positive output terminal OUT+ and the intermediate connection end STR, and between the negative output terminal OUT− and the intermediate connection end STR, and the voltage values between the component-level power electronic modules 22, the voltage abnormality between each component-level power electronic module 22 can be obtained, thereby accurately determining the location of the fault point.

[0108] In the above embodiments, there are various methods for determining a line fault by detecting the voltage relationship among the positive output terminal OUT+, the negative output terminal OUT−, and the intermediate connection terminal STR of each component-level power electronic module 22. Specific descriptions are provided below, but they do not limit the present invention.

[0109] Continuing to refer to Figure 5 、 Figure 6 and Figure 9 , optionally, based on the above embodiments, the positive output terminal OUT+ of the first component-level power electronic module 221 is electrically connected to the negative output terminal OUT− of the second component-level power electronic module 222. The voltage difference V1 between the intermediate connection terminal STR and the positive output terminal OUT+ of the first component-level power electronic module 221 is detected, and the voltage difference V2 between the negative output terminal OUT− and the intermediate connection terminal STR of the second component-level power electronic module 222 is detected. If the sum of the voltage difference V1 and the voltage difference V2 exceeds the normal setting range, there is a fault in the line.

[0110] Among them, the positive output terminal OUT+ of the first component-level power electronic module 221, the negative output terminal OUT− of the second component-level power electronic module 222, the intermediate connection terminal STR of the second component-level power electronic module 222, and the intermediate connection terminal STR of the first component-level power electronic module 221 form a closed loop, satisfying Kirchhoff's voltage law. That is, in any closed loop, when starting from a point and going around the loop back to that point, the algebraic sum of the voltages of each section is always equal to zero. In this closed loop, the voltages of each section mainly come from the voltage difference V1 between the intermediate connection terminal STR and the positive output terminal OUT+ of the first component-level power electronic module 221 and the voltage difference V2 between the negative output terminal OUT− and the intermediate connection terminal STR of the second component-level power electronic module 222. Therefore, the algebraic sum of the voltage difference V1 between the intermediate connection terminal STR and the positive output terminal OUT+ of the first component-level power electronic module 221 and the voltage difference V2 between the negative output terminal OUT− and the intermediate connection terminal STR of the second component-level power electronic module 222 should be 0.

[0111] In an actual circuit, due to losses in the connecting wires and other situations, the actual algebraic sum of the voltages may be slightly greater than 0 or less than 0. Therefore, in the embodiment of the present invention, a threshold is set, and this threshold is the normal setting range. When the sum of the voltage difference V1 and the voltage difference V2 is within the normal setting range, it indicates that there is no fault in this section of the loop. If a disconnection fault occurs at node A or node B, the sum of the voltage difference V1 and the voltage difference V2 at this time will exceed the normal setting range, indicating that there is a fault in the loop between the first component-level power electronic module 221 and the second component-level power electronic module 222. Therefore, the embodiment of the present invention realizes accurate judgment of the fault location, and the judgment method is simple and easy to implement.

[0112] Based on the above embodiments, optionally, the voltage difference V1 is directly measured by a voltage detection device, or the voltage difference V2 is directly measured by a voltage detection device, or both the voltage difference V1 and the voltage difference V2 are directly measured by a voltage detection device.

[0113] Optionally, the voltage detection device can be built into the component-level power electronic module 22, so as to be able to directly detect the voltage difference V1 and / or the voltage difference V2. Such a setting is beneficial to the real-time detection of the voltage difference V1 and / or the voltage difference V2.

[0114] Continue to refer to Figure 5 、 Figure 6 and Figure 9 Based on the above embodiments, optionally, the voltage difference V1 and / or the voltage difference V2 are derived and calculated in an equivalent manner.

[0115] Among them, a voltage detection device for directly detecting the voltage difference V3 between the positive output terminal OUT+ and the negative output terminal OUT- is usually provided in the component-level power electronic module 22. In the embodiments of the present invention, it is also necessary to detect the voltage difference V1 between the positive output terminal OUT+ and the intermediate connection terminal STR of the component-level power electronic module 22, and the voltage difference V2 between the negative output terminal OUT- and the intermediate connection terminal STR. Obviously, for the same component-level power electronic module 22, the voltage difference V1 - the voltage difference V2 = the voltage difference V3. Exemplarily, a set of voltage detection devices is added between the positive output terminal OUT+ and the intermediate connection terminal STR to directly test the voltage difference V1, and the voltage difference V2 = the voltage difference V1 - the voltage difference V3. By using an equivalent method to derive and calculate the voltage difference in the embodiments of the present invention, the use of a set of voltage detection devices can be omitted, which is beneficial to cost reduction.

[0116] Continue to refer to Figure 5 、 Figure 6 and Figure 9 Based on the above embodiments, optionally, after it is determined that a line fault exists, the embodiments of the present invention can also determine the location where the fault occurs according to the sum of the voltage differences V1 and V2 at each position in the photovoltaic string 2. Among them, the fault occurs at the position where the sum of the voltage differences V1 and V2 is the largest or the smallest.

[0117] Exemplarily, when there is a disconnection fault in node A, there is an open-circuit voltage V4 on node A. This open-circuit voltage V4 is the voltage difference between the positive output terminal OUT+ of the first component-level power electronic module 221 and the negative output terminal OUT- of the second component-level power electronic module 222, and this voltage difference is usually not 0. Therefore, in the closed loop where node A is located, the sum of the voltage difference V1, the open-circuit voltage V4, and the voltage difference V2 should be within the normal set range; while the sum of the voltage difference V1 and the voltage difference V2 differs from the normal set range by the open-circuit voltage V4. For the closed loops formed by other adjacent two component-level power electronic modules 22, the sum of the voltage difference V1 and the voltage difference V2 is still within the normal set range.

[0118] Figure 10 FIG. is a partial structural schematic diagram of another photovoltaic module safety management system provided by an embodiment of the present invention. Refer to Figure 10 , on the basis of the above embodiments, optionally, a third component-level power electronic module 223 is further connected in series between the first component-level power electronic module 221 and the second component-level power electronic module 222. Fault detection is performed through the closed loop formed by the first component-level power electronic module 221, the third component-level power electronic module 223, and the second component-level power electronic module 222.

[0119] Among them, the positive output terminal OUT+ of the first component-level power electronic module 221 is electrically connected to the negative output terminal OUT- of the third component-level power electronic module 223, the positive output terminal OUT+ of the third component-level power electronic module 223 is electrically connected to the negative output terminal OUT- of the second component-level power electronic module 222, and the intermediate connection terminal STR of the first component-level power electronic module 221 is electrically connected to the intermediate connection terminal STR of the second component-level power electronic module 222 through the common connection line 3, thereby forming a closed loop. In this closed loop, the fault point can be judged by detecting the sum of the voltage difference V1, the voltage difference V5 between the positive output terminal OUT+ and the negative output terminal OUT- of the third component-level power electronic module 223, and the voltage difference V2. If the voltage value after summing the three is greater than the normal set range, it means that a fault has occurred in the line between the first component-level power electronic module 221 and the second component-level power electronic module 222.

[0120] Compared with the foregoing embodiments, the number of voltage differences included in the closed loop of this embodiment is relatively large, but the number of voltage detection devices can be saved. For example, in the third component-level power electronic module 223, there is no need to set a voltage detection device for detecting the voltage between the positive output terminal OUT+ and the intermediate connection terminal STR, nor is it necessary to set a voltage detection device for detecting the voltage between the negative output terminal OUT- and the intermediate connection terminal STR.

[0121] Figure 11FIG. 0 is a partial structural schematic diagram of another photovoltaic module safety management system provided by an embodiment of the present invention. Refer to Figure 11 , in another embodiment of the present invention, optionally, at least two third component-level power electronic modules 223 are further connected in series between the first component-level power electronic module 221 and the second component-level power electronic module 222. Fault detection is performed through a closed loop formed by the first component-level power electronic module 221, at least two third component-level power electronic modules 223, and the second component-level power electronic module 222. The technical principle is similar to that of the foregoing embodiment and will not be elaborated herein.

[0122] It should be noted that in the above embodiments, the principle of Kirchhoff's voltage law of the closed loop is exemplarily used for fault judgment, which is not a limitation to the present invention. In other embodiments, fault judgment can also be performed according to the characteristics of the voltage difference between the positive output terminal OUT+ (or negative output terminal OUT-) and the intermediate connection terminal STR. Specific description is as follows.

[0123] In one embodiment of the present invention, optionally, the method for judging a line fault specifically includes: detecting the electrical parameter fluctuation between the intermediate connection terminal STR and the positive output terminal OUT+ of the component-level power electronic module 22. If the electrical parameter fluctuation exceeds the normal set range, there is a fault in the line.

[0124] In another embodiment of the present invention, optionally, the method for judging a line fault specifically includes: detecting the electrical parameter fluctuation between the intermediate connection terminal STR and the negative output terminal OUT- of the component-level power electronic module 22. If the electrical parameter fluctuation exceeds the normal set range, there is a fault in the line.

[0125] Optionally, the electrical parameters include at least one of the voltage magnitude, the magnitude of the set frequency component of the voltage, the change law of the voltage, the change law of the set frequency component of the voltage, and the spectral distribution characteristics of the voltage.

[0126] Based on the above embodiments, optionally, after it is determined that there is a fault in the line, it further includes: judging the position where the fault occurs according to the electrical parameter fluctuation at each position in the photovoltaic string 2. Among them, the fault occurs at the position with the largest electrical parameter fluctuation.

[0127] Specifically, through the electrical parameter fluctuation between the intermediate connection terminal STR and the positive output terminal OUT+ (or negative output terminal OUT-) of each component-level power electronic module 22, and by the component-level power electronic module 22 or the central processing unit, the position with the largest electrical parameter fluctuation is judged, so as to quickly obtain the position where the fault occurs and realize the detection and positioning of the fault.

[0128] Among them, the common connection line 3 is the connection line connecting the busbars, and the voltage thereon is relatively stable. In the embodiment of the present invention, the voltage at the intermediate connection point STR connecting the common connection line 3 is used as a reference. By detecting the voltage difference between the positive output terminal OUT+ (or negative output terminal OUT-) and the common connection line 3, it is equivalent to finding a reference point for the detection of each voltage difference, and the voltage detection will be more accurate. Therefore, by judging the characteristics of the voltage difference between the positive output terminal OUT+ (or negative output terminal OUT-) of each component-level power electronic module 22 and the intermediate connection terminal STR, the fault location can be accurately judged, and the sensitivity of voltage detection is improved.

[0129] Based on the above embodiments, optionally, the fault types include: disconnection, poor contact, and arc.

[0130] Based on the above embodiments, optionally, the voltage values detected by the component-level power electronic modules 22 are propagated to each other through communication. The method for judging line faults is executed in the component-level power electronic module 22; or, the method for judging line faults is executed in a central controller that communicates with the component-level power electronic module 22.

[0131] Among them, the component-level power electronic modules 22 can communicate with each other, and in some embodiments, they can also be communicatively connected to an external central controller. When a fault judgment is made, the voltage values detected by each component-level power electronic module 22 can be transmitted into other component-level power electronic modules 22, and self-fault judgments are made through the voltage data received by each component-level power electronic module 22. The voltage values detected by each component-level power electronic module 22 can also be transmitted into an external central controller, and the central processor executes the various methods and processes described above, such as the method for judging line faults, and performs fault detection through the voltage data detected by each component-level power electronic module 22.

[0132] Continue to refer to Figure 7 、 Figure 8 and Figure 9 , in an embodiment of the present invention, optionally, the fault detection circuit 202 includes a first current terminal S1 and a second current terminal S2, and the common connection line 3 of the photovoltaic string 21 sequentially passes through the first current terminal S1 and the second current terminal S2 of each component-level power electronic module. The structure of this fault detection circuit 202 is applicable to the fault detection using voltage relationships in any of the above embodiments, and its technical principle and the resulting effects are similar. In addition, the structure of this fault detection circuit 202 can also use current relationships for fault detection. Among them, when using current relationships for fault detection, leakage faults can also be detected. The specific description is as follows:

[0133] In an embodiment of the present invention, optionally, the component-level power electronic module 22 can be used to detect at least one of the voltage between its positive output terminal OUT+ and the second current terminal S2, the voltage between its negative output terminal OUT- and the first current terminal S1, and the voltage between the positive output terminal OUT+ and the negative output terminal OUT-. When a fault occurs on the line, the embodiment of the present invention can analyze and judge the voltage values between the component-level power electronic modules 22 by the voltage differences between the positive output terminal OUT+ and the second current terminal S2, and between the negative output terminal OUT- and the first current terminal S1, so as to obtain the abnormal voltage conditions between the component-level power electronic modules 22, and thus accurately determine the location of the fault point.

[0134] In the above embodiments, there are various methods for judging line faults by detecting the voltage relationship between the positive output terminal OUT+ of each component-level power electronic module 22 and the second current terminal S2, and the voltage relationship between the negative output terminal OUT- and the first current terminal S1. Specific descriptions are as follows, but they are not intended to limit the present invention.

[0135] Continue to refer to Figure 7 、 Figure 8 and Figure 9 , on the basis of the above embodiments, optionally, the positive output terminal OUT+ of the first component-level power electronic module 221 is electrically connected to the negative output terminal OUT- of the second component-level power electronic module 222; the second current terminal S2 of the first component-level power electronic module 221 is electrically connected to the first current terminal S1 of the second component-level power electronic module 222. Detect the voltage difference V1 between the current terminal of the first component-level power electronic module 211 and the positive output terminal OUT+, and detect the voltage difference V2 between the negative output terminal OUT- of the second component-level power electronic module 222 and the current terminal; where the current terminal is the first current terminal S1 or the second current terminal S2. If the sum of the voltage difference V1 and the voltage difference V2 exceeds the normal set range, there is a fault in the line.

[0136] Among them, the positive output terminal OUT+ of the first component-level power electronic module 221, the negative output terminal OUT- of the second component-level power electronic module 222, the first current terminal S1 of the second component-level power electronic module 222, and the second current terminal S2 of the first component-level power electronic module 221 form a closed loop, which satisfies Kirchhoff's voltage law. That is, in any closed loop, when starting from a point and going around the loop back to this point, the algebraic sum of the voltages of each section is always equal to zero. In this closed loop, the voltages of each section mainly come from the voltage difference V1 between the second current terminal S2 and the positive output terminal OUT+ of the first component-level power electronic module 221 and the voltage difference V2 between the negative output terminal OUT- and the first current terminal S1 of the second component-level power electronic module 222. Therefore, the algebraic sum of the voltage difference V1 between the second current terminal S2 and the positive output terminal OUT+ of the first component-level power electronic module 221 and the voltage difference V2 between the negative output terminal OUT- and the first current terminal S1 of the second component-level power electronic module 222 should be 0. Exemplarily, the voltage difference V1 can also be the voltage difference between the first current terminal S1 and the positive output terminal OUT+ of the first component-level power electronic module 221, and the voltage difference V2 can also be the voltage difference between the second current terminal S2 and the negative output terminal OUT- of the second component-level power electronic module 221.

[0137] In an actual circuit, due to losses in the connecting wires and other situations, the algebraic sum of the actual voltages may be slightly greater than 0 or less than 0. Therefore, in the embodiment of the present invention, a threshold is set, and this threshold is within a normal setting range. When the sum of the voltage difference V1 and the voltage difference V2 is within the normal setting range, it indicates that there is no fault in this section of the loop. If a disconnection fault occurs at node A or node B, the sum of the voltage difference V1 and the voltage difference V2 at this time will exceed the normal setting range, indicating that a fault has occurred in the loop between the first component-level power electronic module 221 and the second component-level power electronic module 222. Therefore, the embodiment of the present invention realizes accurate judgment of the fault location, and the judgment method is simple and easy to implement.

[0138] On the basis of the above embodiments, optionally, the voltage difference V1 is directly measured by a voltage detection device, or the voltage difference V2 is directly measured by a voltage detection device, or both the voltage difference V1 and the voltage difference V2 are directly measured by a voltage detection device.

[0139] Optionally, the voltage detection device can be built into the component-level power electronic module 22, so as to directly detect the voltage difference V1 and / or the voltage difference V2. Such a setting is beneficial to the real-time detection of the voltage difference V1 and / or the voltage difference V2.

[0140] Continue to refer to Figure 7 、 Figure 8 and Figure 9, on the basis of the above embodiments, optionally, the voltage difference V1 and / or the voltage difference V2 are derived and calculated in an equivalent manner.

[0141] Among them, a voltage detection device for directly detecting the voltage difference V3 between the positive output terminal OUT+ and the negative output terminal OUT- is usually provided in the component-level power electronic module 22. In the embodiments of the present invention, it is also necessary to detect the voltage difference V1 between the positive output terminal OUT+ of the component-level power electronic module 22 and the second current terminal S2, and the voltage difference V2 between the negative output terminal OUT- and the first current terminal S1. Obviously, for the same component-level power electronic module 22, the voltage difference V1 - the voltage difference V2 = the voltage difference V3. Exemplarily, a set of voltage detection devices is added between the positive output terminal OUT+ and the second current terminal S2 to directly test the voltage difference V1, and the voltage difference V2 = the voltage difference V1 - the voltage difference V3. By deriving and calculating the voltage difference in an equivalent manner in the embodiments of the present invention, the use of a set of voltage detection devices can be omitted, which is beneficial to reducing costs.

[0142] Continue to refer to Figure 7 , Figure 8 and Figure 9 , on the basis of the above embodiments, optionally, after it is determined that a line fault exists, the embodiments of the present invention can also determine the location where the fault occurs according to the sum of the voltage differences V1 and V2 at each position in the photovoltaic string 2. Among them, the fault occurs at the position where the sum of the voltage differences V1 and V2 is the largest or the smallest.

[0143] Exemplarily, when there is an open fault at node A, there is an open-circuit voltage V4 at node A. The open-circuit voltage V4 is the voltage difference between the positive output terminal OUT+ of the first component-level power electronic module 221 and the negative output terminal OUT- of the second component-level power electronic module 222, and this voltage difference is usually not zero. Therefore, in the closed loop where node A is located, the sum of the voltage difference V1, the open-circuit voltage V4, and the voltage difference V2 should be within the normal set range; while the sum of the voltage difference V1 and the voltage difference V2 differs from the normal set range by the open-circuit voltage V4. For the closed loops formed by other adjacent two component-level power electronic modules 22, the sum of the voltage difference V1 and the voltage difference V2 is still within the normal set range.

[0144] Figure 12 It is a partial structural schematic diagram of another photovoltaic module safety management system provided by the embodiments of the present invention. Refer to Figure 12, based on the above embodiments, optionally, at least one component-level power electronic module 223 is further connected in series between the first component-level power electronic module 221 and the second component-level power electronic module 222. Fault detection is performed through a closed loop formed by the first component-level power electronic module 221, the third component-level power electronic module 223, and the second component-level power electronic module 222.

[0145] Among them, the positive output terminal OUT+ of the first component-level power electronic module 221 is electrically connected to the negative output terminal OUT- of the third component-level power electronic module 223, the positive output terminal OUT+ of the third component-level power electronic module 223 is electrically connected to the negative output terminal OUT- of the second component-level power electronic module 222, and the second current terminal S2 of the first component-level power electronic module 221 is electrically connected to the first current terminal S1 of the third component-level power electronic module 223 through a common connection line 3, and the second current terminal S2 of the third component-level power electronic module 223 is electrically connected to the first current terminal S1 of the second component-level power electronic module 222, thereby forming a closed loop. In this closed loop, the fault point can be judged by detecting the sum of the voltage difference V1, the voltage difference V5 between the positive output terminal OUT+ and the negative output terminal OUT- of the third component-level power electronic module 223, and the voltage difference V2. If the voltage value after summing the three is greater than the normal set range, it means that a fault has occurred in the line between the first component-level power electronic module 221 and the second component-level power electronic module 222.

[0146] Compared with the foregoing embodiments, the number of voltage differences included in the closed loop of this embodiment is relatively large, but the number of voltage detection devices can be saved. For example, in the third component-level power electronic module 223, there is no need to set a voltage detection device for detecting the voltage between the positive output terminal OUT+ and the second current terminal S2, nor a voltage detection device for detecting the voltage between the negative output terminal OUT- and the first current terminal S1.

[0147] Figure 13 This is a schematic diagram of a partial structure of another photovoltaic module safety management system provided by an embodiment of the present invention. Refer to Figure 13 , in another embodiment of the present invention, optionally, at least two third component-level power electronic modules 223 are further connected in series between the first component-level power electronic module 221 and the second component-level power electronic module 222. Fault detection is performed through a closed loop formed by the first component-level power electronic module 221, at least two third component-level power electronic modules 223, and the second component-level power electronic module 222. The technical principle is similar to that of the foregoing embodiment and will not be elaborated here.

[0148] It should be noted that in the above embodiments, the principle of Kirchhoff's voltage law of a closed loop is exemplarily used for fault judgment, which is not a limitation of the present invention. In other embodiments, fault judgment can also be performed according to the characteristics of the voltage difference between the positive output terminal OUT+ (or the negative output terminal OUT-) and the common connection line 3. Specific descriptions are as follows.

[0149] In an embodiment of the present invention, optionally, the method for judging a line fault specifically includes: detecting the electrical parameter fluctuation between the current terminal and the output terminal of the component-level power electronic module 22; wherein, the current terminal is the first current terminal S1 or the second current terminal S2; the output terminal is the positive output terminal OUT+ or the negative output terminal OUT-. If the electrical parameter fluctuation exceeds the normal set range, there is a fault in the line.

[0150] Optionally, the electrical parameters include at least one of the voltage magnitude, the magnitude of the set frequency component of the voltage, the variation law of the voltage, the variation law of the set frequency component of the voltage, and the spectral distribution characteristics of the voltage.

[0151] Based on the above embodiments, optionally, after it is determined that there is a fault in the line, it further includes: judging the position where the fault occurs according to the electrical parameter fluctuation at each position in the photovoltaic string 2. Among them, the fault occurs at the position with the largest electrical parameter fluctuation.

[0152] Specifically, by the electrical parameter fluctuation between the second current terminal S2 and the positive output terminal OUT+ of each component-level power electronic module 22, or by the electrical parameter fluctuation between the first current terminal S1 and the negative output terminal OUT- of each component-level power electronic module 22, and judging the position with the largest electrical parameter fluctuation through the component-level power electronic module 22 or the central processing unit, the position where the fault occurs can be quickly obtained, realizing the detection and positioning of the fault.

[0153] Among them, the common connection line 3 is the connection line connecting the busbars, and the voltage thereon is relatively stable. In the embodiment of the present invention, the voltage on the first current terminal S1 or the second current terminal S2 connecting the common connection line 3 is used as a reference. By detecting the voltage difference between the positive output terminal OUT+ (or the negative output terminal OUT-) and the common connection line 3, a reference point is found for the detection of each voltage difference, and the voltage detection will be more accurate. Therefore, by judging the characteristics of the voltage difference between the positive output terminal OUT+ and the second current terminal S2 or the voltage difference between the negative output terminal OUT- and the second current terminal S2 of each component-level power electronic module 22, the fault position can be accurately judged, and the sensitivity of voltage detection is improved.

[0154] Based on the above embodiments, optionally, the fault types that can be detected by using the voltage relationship include: disconnection, poor contact, and arc.

[0155] Figure 14 This is a partial structural schematic diagram of another safety management system for a photovoltaic module provided by an embodiment of the present invention. Refer to Figure 7 , Figure 9 and Figure 14 , in another embodiment of the present invention, optionally, the method for judging a line fault specifically includes: detecting the current difference between the output end of the component-level power electronic module 22 and the first current end S1. Wherein, the output end is the positive output end OUT+ or the negative output end OUT-, and if the current difference exceeds the normal set range, there is a fault in the line.

[0156] Among them, since each photovoltaic module 21 is connected in series, the current everywhere in this series loop should be equal. Specifically, the positive output end OUT+ of the first component-level power electronic module 221, the negative output end OUT- of the second component-level power electronic module 222, the positive output end OUT+ of the second component-level power electronic module 222, ……, the second current end S2 of the second component-level power electronic module 222, the first current end S1 of the second component-level power electronic module 222, the second current end S2 of the first component-level power electronic module 221, and the first current end S1 of the first component-level power electronic module 221 form a series loop, and the current in this loop is equal everywhere. Further, the positive output end OUT+ of the first component-level power electronic module 221, the negative output end OUT- of the second component-level power electronic module 222, the first current end S1 of the second component-level power electronic module 222, and the second current end S2 of the first component-level power electronic module 221 form a closed loop, and in a closed loop, the loop current everywhere is equal. In this closed loop, the negative output end OUT- and the first current end S1 of the second component-level power electronic module 222 are both connected to the second component-level power electronic module 222. Therefore, the negative output end OUT- and the first current end S1 of the second component-level power electronic module 222 should satisfy Kirchhoff's current law, and the input current of the negative output end OUT- of the second component-level power electronic module 222 should be equal to the output current of the first current end S1, and the difference between the two should be 0.

[0157] In an actual circuit, due to losses in the connection wires and other situations, the actual loop currents of each section may be slightly different. Therefore, an embodiment of the present invention sets a threshold, which is the normal set range. When the current difference between the negative output end OUT- of the component-level power electronic module 22 and the first current end S1 is within the normal set range, it indicates that there is no fault in this section of the loop. Therefore, the embodiment of the present invention realizes the detection of current faults and can be used to reflect leakage faults.

[0158] Similarly, in this closed loop, the positive output terminal OUT+ and the second current terminal S2 of the first component-level power electronic module 221 are both connected to the first component-level power electronic module 221. Therefore, the positive output terminal OUT+ and the second current terminal S2 of the first component-level power electronic module 221 should satisfy Kirchhoff's current law, and the output current of the positive output terminal OUT+ of the first component-level power electronic module 221 should be equal to the input current of the second current terminal S2, and the difference between the two should be 0. In practical applications, it can be determined as needed whether to detect the current between the negative output terminal OUT- and the first current terminal S1 of the component-level power electronic module 22, or to detect the current between the positive output terminal OUT+ and the second current terminal S2 of the component-level power electronic module 22. In other embodiments, it is also possible to detect the current between the negative output terminal OUT- and the second current terminal S2 of the component-level power electronic module 22, or to detect the current between the positive output terminal OUT+ and the first current terminal S1 of the component-level power electronic module 22.

[0159] Continue to refer to Figure 7 、 Figure 9 and Figure 14 , based on the above embodiments, optionally, after determining that there is a fault in the line, it further includes: obtaining the distribution of the current differences according to the current differences at each position in the photovoltaic string 2; and determining the location where the fault occurs according to the distribution.

[0160] Exemplarily, when leakage occurs at node A, the current detected at the negative output terminal OUT- of the second component-level power electronic module 222 decreases, and the current difference between the negative output terminal OUT- and the first current terminal S1 of the second component-level power electronic module 222 increases and exceeds the normal set range; the current difference between the positive output terminal OUT+ and the second current terminal S2 of the second component-level power electronic module 222 is still within the normal set range; the current difference between the positive output terminal OUT+ and the second current terminal S2 of the first component-level power electronic module 221 increases and exceeds the normal set range; the current difference between the negative output terminal OUT- and the first current terminal S1 of the first component-level power electronic module 221 is still within the normal set range. Thus, it can be determined that the leakage occurs on the line between the first component-level power electronic module 221 and the second component-level power electronic module 222.

[0161] Based on the above embodiments, optionally, the voltage values and / or current values detected by the component-level power electronic module 22 are propagated to each other through communication. The method for judging line faults is executed in the component-level power electronic module 22; or, the method for judging line faults is executed in a central controller that communicates with the component-level power electronic module 22.

[0162] Among them, each component-level power electronic module 22 can communicate with each other and can also be communicatively connected to an external central controller in some embodiments. When a fault judgment is made, the voltage value and / or current value detected by each component-level power electronic module 22 can be transmitted to other component-level power electronic modules 22, and a self-fault judgment is made based on the voltage data received by each component-level power electronic module 22. The voltage value and / or current value detected by each component-level power electronic module 22 can also be transmitted to the external central controller, and the central processor executes each method and process described above, such as the method for judging a line fault, and performs fault detection based on the voltage data detected by each component-level power electronic module 22.

[0163] In the above embodiments, the central processor can be various general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of the central processor include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc.

[0164] It should be understood that various forms of the processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved, and no limitation is imposed herein.

[0165] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A safety management system for a photovoltaic module, characterized in that, Comprising: A plurality of photovoltaic strings, and the plurality of photovoltaic strings supply power to a bus; the photovoltaic strings include a plurality of photovoltaic modules and a plurality of component-level power electronic modules, and at least one of the photovoltaic modules is electrically connected to the corresponding component-level power electronic module; Wherein, the component-level power electronic module includes: a positive output terminal, a negative output terminal, and a fault detection circuit; the component-level power electronic modules in the same photovoltaic string are connected in series through the positive output terminal and the negative output terminal; the fault detection circuits of the component-level power electronic modules in the same photovoltaic string are all electrically connected to a common connection line.

2. The safety management system of a photovoltaic module according to claim 1, characterized in that, The fault detection circuit includes an intermediate connection terminal; the intermediate connection terminals of the component-level power electronic modules in the same photovoltaic string are all connected to the common connection line.

3. The safety management system for a photovoltaic module according to claim 2, wherein, The intermediate connection terminal of the component-level power electronic module is electrically connected or not electrically connected to a circuit node in the component-level power electronic module.

4. The safety management system of a photovoltaic module according to claim 1, wherein The fault detection circuit includes a first current terminal and a second current terminal, and the first current terminal and the second current terminal are electrically connected; the common connection line of the photovoltaic string sequentially passes through the first current terminal and the second current terminal of each component-level power electronic module.

5. The safety management system for a photovoltaic module according to claim 1, characterized in that, The component-level power electronic module is a disconnector or an optimizer.

6. A safety management method for a photovoltaic module, characterized in that, Comprising: A plurality of photovoltaic strings supply power to a bus; A plurality of photovoltaic modules in each photovoltaic string are connected in series through correspondingly arranged component-level power electronic modules; wherein, the fault detection circuit of the component-level power electronic module is electrically connected to a common connection line; Detect the electrical parameter relationships of the positive output terminal, the negative output terminal, and the fault detection circuit of each component-level power electronic module to judge a line fault.

7. The safety management method for a photovoltaic module according to claim 6, characterized in that, The method for judging a line fault specifically includes: If the closed loop formed by the positive output terminal, the negative output terminal, and the fault detection circuit of two adjacent component-level power electronic modules does not satisfy Kirchhoff's law, then there is a fault in the line.

8. The safety management method for a photovoltaic module according to claim 7, characterized in that, The fault detection circuit includes an intermediate connection terminal; the intermediate connection terminals of the component-level power electronic modules in the same photovoltaic string are all connected to the common connection line; the method for judging a line fault specifically includes: The positive output terminal of the first component-level power electronic module is electrically connected to the negative output terminal of the second component-level power electronic module; Detect the voltage difference V1 between the intermediate connection terminal and the positive output terminal of the first component-level power electronic module, and detect the voltage difference V2 between the negative output terminal and the intermediate connection terminal of the second component-level power electronic module; If the sum of the voltage difference V1 and the voltage difference V2 exceeds the normal set range, then there is a fault in the line.

9. The safety management method of the photovoltaic module according to claim 6, wherein The fault detection circuit includes an intermediate connection terminal; the intermediate connection terminals of the component-level power electronic modules in the same photovoltaic string are all connected to the common connection line; the method for judging a line fault specifically includes: Detect the electrical parameter fluctuation between the intermediate connection terminal and the positive output terminal of the component-level power electronic module; If the electrical parameter fluctuation exceeds the normal set range, then there is a fault in the line.

10. The safety management method for a photovoltaic module according to claim 6, characterized in that The fault detection circuit includes an intermediate connection terminal; the intermediate connection terminals of the component-level power electronic modules in the same photovoltaic string are all connected to a common connection line; the method for judging a line fault specifically includes: Detect the electrical parameter fluctuation between the intermediate connection terminal and the negative output terminal of the component-level power electronic module; If the electrical parameter fluctuation exceeds the normal set range, there is a fault in the line.

11. The safety management method of the photovoltaic module according to claim 7, characterized in that, The fault detection circuit includes a first current terminal and a second current terminal, and the first current terminal and the second current terminal are electrically connected; the common connection line of the photovoltaic string sequentially passes through the first current terminal and the second current terminal of each component-level power electronic module; The method for judging a line fault specifically includes: The positive output terminal of the first component-level power electronic module is electrically connected to the negative output terminal of the second component-level power electronic module; The second current terminal of the first component-level power electronic module is electrically connected to the first current terminal of the second component-level power electronic module; Detect the voltage difference V1 between the current terminal and the positive output terminal of the first component-level power electronic module, and detect the voltage difference V2 between the negative output terminal and the current terminal of the second component-level power electronic module; wherein, the current terminal is the first current terminal or the second current terminal; If the sum of the voltage difference V1 and the voltage difference V2 exceeds the normal set range, there is a fault in the line.

12. The safety management method of a photovoltaic module according to claim 8 or 11, characterized in that, The voltage difference V1 and / or the voltage difference V2 are measured by a voltage detection device.

13. The safety management method of the photovoltaic module according to claim 8 or 11, characterized in that, The voltage difference V1 and / or the voltage difference V2 are derived and calculated in an equivalent manner.

14. The safety management method of a photovoltaic module according to claim 8 or 11, characterized in that, After it is judged that there is a fault in the line, it further includes: Judging the location where the fault occurs according to the sum of the voltage difference V1 and the voltage difference V2 at each position in the photovoltaic string; Wherein, the fault occurs at the position where the sum of the voltage difference V1 and the voltage difference V2 is the largest.

15. The safety management method for a photovoltaic module according to claim 8 or 11, characterized in that, At least one component-level power electronic module is further connected in series between the first component-level power electronic module and the second component-level power electronic module.

16. The safety management method for a photovoltaic module according to any one of claims 8-11, characterized in that, The voltage values detected by the component-level power electronic modules are propagated to each other through communication; The method for judging a line fault is executed in the component-level power electronic module; or, the method for judging a line fault is executed in a central controller that communicates with the component-level power electronic module.

17. The safety management method for a photovoltaic module according to claim 6, wherein The fault detection circuit includes a first current terminal and a second current terminal, and the first current terminal and the second current terminal are electrically connected; the common connection line of the photovoltaic string sequentially passes through the first current terminal and the second current terminal of each component-level power electronic module; The method for judging a line fault specifically includes: Detect the electrical parameter fluctuation between the current terminal and the output terminal of the component-level power electronic module; wherein, the current terminal is the first current terminal or the second current terminal; the output terminal is the positive output terminal or the negative output terminal; If the electrical parameter fluctuation exceeds the normal set range, there is a fault in the line.

18. The safety management method of a photovoltaic module according to claim 9, 10 or 17, characterized in that, The electrical parameters include at least one of the magnitude of the voltage, the magnitude of the set frequency component of the voltage, the variation law of the voltage, the variation law of the set frequency component of the voltage, and the spectral distribution characteristics of the voltage.

19. The safety management method for a photovoltaic module according to claim 9, 10 or 17, characterized in that, After it is determined that there is a line fault, it further includes: Judging the location where the fault occurs according to the fluctuations of the electrical parameters at each position in the photovoltaic string; Wherein, the fault occurs at the position with the largest fluctuation of the electrical parameters.

20. The safety management method of a photovoltaic module according to claim 6, wherein, The fault detection circuit includes a first current terminal and a second current terminal, and the first current terminal and the second current terminal are electrically connected; the common connection line of the photovoltaic string sequentially passes through the first current terminal and the second current terminal of each of the component-level power electronic modules; The method for judging the line fault specifically includes: Detecting the current difference between the output terminal and the first current terminal of the component-level power electronic module; the output terminal is the positive output terminal or the negative output terminal; If the current difference exceeds the normal set range, there is a line fault.

21. The safety management method for a photovoltaic module according to claim 20, characterized in that, After it is determined that there is a line fault, it further includes: Obtaining the distribution of the current differences according to the current differences at each position in the photovoltaic string; Judging the location where the fault occurs according to the distribution.

22. The safety management method of the photovoltaic module according to claim 6, characterized in that, The fault types include: disconnection, poor contact, arc, and leakage.

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