Protection system and protection method for power converter, and related apparatus

Abstract

A protection system and protection method for a power converter, and a related apparatus. In the protection system, a hardware protection circuit (10) and a control module (20) respectively perform threshold comparison on the basis of direct-current side electrical parameter sampling information, and generate and output protection signals when the direct-current side electrical parameter sampling information satisfies a preset protection condition; when the hardware protection circuit (10) or the control module (20) outputs the protection signal, a trigger signal can be outputted by means of a first logic gate (30) to a control terminal of an actuation fuse on a direct-current side of the power converter, so as to control the corresponding actuation fuse to break, thereby implementing overcurrent protection.

Description

A protection system, protection method, and related devices for a power converter.

[0001] This disclosure claims priority to Chinese patent applications filed on January 23, 2025, with application number 202510125340.5, entitled "A Protection System and Protection Method and Related Device for a Power Converter," and on May 26, 2025, with application number 202510685631.X, also entitled "A Protection System and Protection Method and Related Device for a Power Converter," the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to a protection system and method for a power converter, as well as related devices. Background Technology

[0003] Power converters typically require overcurrent protection measures to protect against overcurrent faults such as short circuits. For example, on the DC side of a power converter, fuses are generally used for overcurrent protection. However, relying on the fuse's own characteristics to interrupt the fault current requires waiting for electrical energy to be converted into heat energy and for the temperature to rise to the melting point, resulting in a long breaking time. Summary of the Invention

[0004] The following is an overview of the detailed description of this disclosure. This overview is not intended to limit the scope of the claims. This disclosure provides a protection system and method for a power converter, as well as related apparatus. The technical solutions adopted in this disclosure are as follows:

[0005] The first aspect of this disclosure provides a protection system for a power converter, comprising: a hardware protection circuit, a control module, and at least one first logic gate; wherein...

[0006] Both the input terminals of the hardware protection circuit and the control module receive DC-side electrical parameter sampling information from the power converter.

[0007] The two inputs of the first logic gate are connected to the output of the hardware protection circuit and the output of the control module, respectively.

[0008] The output of the first logic gate is used to connect to the control terminal of the excitation fuse on the DC side of the power converter;

[0009] The hardware protection circuit and control module are respectively configured to perform threshold comparison based on the DC side electrical parameter sampling information, and generate and output protection signals when the DC side electrical parameter sampling information meets the preset protection conditions, so that the first logic gate outputs a trigger signal to control the corresponding excitation fuse to break.

[0010] In one possible implementation, the number of the first logic gate is 1, and the output of the first logic gate is connected to the control terminal of each excitation fuse on the DC side of the power converter.

[0011] Alternatively, the number of first logic gates is greater than 1, the output of each first logic gate is connected to the control terminal of the corresponding excitation fuse on the DC side of the power converter, and the two input terminals of the first logic gate are connected to the corresponding output terminals of the hardware protection circuit and the corresponding output terminals of the control module, respectively.

[0012] In one possible implementation, the DC side electrical parameter sampling information includes: the current information of each branch on the DC side; the preset protection conditions include: the reverse current value of each branch current information is greater than a first current threshold.

[0013] Alternatively, the DC side electrical parameter sampling information includes at least two of the following: branch current information, DC side branch voltage information, and DC bus voltage information; the preset protection conditions include at least two of the following conditions: the reverse current value of each branch current information is greater than the first current threshold, the voltage value of each branch voltage information is less than the branch voltage threshold, and the DC bus voltage information is greater than the bus voltage threshold.

[0014] In one possible implementation, where the power converter is a centralized photovoltaic inverter system, the DC-side electrical parameter sampling information includes: current information of each branch and voltage information of each branch on the DC side; the preset protection conditions include: a reverse current value in the reverse current information of each branch is greater than a first current threshold, and a voltage value in the voltage information of each branch is less than a branch voltage threshold; or, the DC-side electrical parameter sampling information includes: current information of each branch and DC bus voltage information; the preset protection conditions include: a reverse current value in the reverse current information of each branch is greater than a first current threshold, and a DC bus voltage information is less than a bus voltage threshold.

[0015] Alternatively, if the power converter is a string photovoltaic inverter system, the DC side electrical parameter sampling information includes at least two of the following: branch current information, branch voltage information, and DC bus voltage information; the preset protection conditions include at least two of the following conditions: the reverse current value of each branch current information is greater than the first current threshold, the voltage value of each branch voltage information is less than the branch voltage threshold, and the DC bus voltage information is greater than the bus voltage threshold.

[0016] Alternatively, if the power converter is a distributed photovoltaic inverter system, the DC side electrical parameter sampling information includes at least two of the following: current information of each branch, voltage information of each power supply on the DC side, and DC bus voltage information; the preset protection conditions include at least two of the following conditions: the reverse current value of each branch current information is greater than the first current threshold, the voltage value of each power supply voltage information is less than the power supply voltage threshold, and the DC bus voltage information is greater than the bus voltage threshold.

[0017] In one possible implementation, the number of the first logic gates is 1, and the hardware protection circuit includes: a first comparator circuit;

[0018] One input of the first comparator circuit receives the maximum value of the reverse current information of each branch.

[0019] The other input of the first comparator circuit receives the first current threshold.

[0020] The output of the first comparator circuit serves as the output of the hardware protection circuit.

[0021] In one possible implementation, the number of the first logic gate is 1, and the hardware protection circuit includes: a second comparison circuit, a third comparison circuit, and the second logic gate;

[0022] One input of the second comparator circuit receives one of the following: the maximum reverse current value of each branch current information, the minimum voltage value of each branch voltage information, and the DC bus voltage information.

[0023] The other input of the second comparator circuit receives the corresponding threshold.

[0024] The output of the second comparator circuit is connected to one input of the second logic gate.

[0025] One input of the third comparator circuit receives the maximum reverse current value of each branch current information, the minimum voltage value of each branch voltage information, and another of the DC bus voltage information.

[0026] The other input of the third comparator circuit receives the corresponding threshold.

[0027] The output of the third comparator circuit is connected to the other input of the second logic gate;

[0028] The output of the second logic gate serves as the output of the hardware protection circuit.

[0029] In one possible implementation, the number of the first logic gate is 1, and the hardware protection circuit includes: a second comparison circuit, a third comparison circuit, and the second logic gate;

[0030] One input terminal of the second comparator circuit receives, when the power converter is a centralized photovoltaic inverter system, the maximum reverse current value of each branch current information; when the power converter is a string photovoltaic inverter system, it receives one of the following: the maximum reverse current value of each branch current information, the minimum voltage value of each branch voltage information, and the DC bus voltage information; when the power converter is a distributed photovoltaic inverter system, it receives one of the following: the maximum reverse current value of each branch current information, the minimum voltage value of each power supply voltage information, and the DC bus voltage information.

[0031] The other input of the second comparator circuit receives the corresponding threshold.

[0032] The output of the second comparator circuit is connected to one input of the second logic gate.

[0033] One input of the third comparator circuit receives either the minimum voltage of each branch voltage information or the DC bus voltage information when the power converter is a centralized photovoltaic inverter system; or, when the power converter is a string photovoltaic inverter system, it receives either the maximum reverse current value of each branch current information, the minimum voltage of each branch voltage information, or another of the DC bus voltage information; or, when the power converter is a distributed photovoltaic inverter system, it receives either the maximum reverse current value of each branch current information, the minimum voltage of each power supply voltage information, or another of the DC bus voltage information.

[0034] The other input of the third comparator circuit receives the corresponding threshold.

[0035] The output of the third comparator circuit is connected to the other input of the second logic gate;

[0036] The output of the second logic gate serves as the output of the hardware protection circuit.

[0037] In one possible implementation, one input of the second comparator circuit receives the maximum value of the reverse current value of each branch current information, and the other input of the second comparator circuit receives the first current threshold.

[0038] One input of the third comparator circuit receives the DC bus voltage information, and the other input of the third comparator circuit receives the bus voltage threshold.

[0039] In one possible implementation, the number of first logic gates is greater than 1, and the hardware protection circuit includes: multiple first comparison circuits;

[0040] Each input terminal of the first comparator circuit receives the reverse current value of the corresponding branch current information.

[0041] The other input terminal of each of the first comparison circuits receives the first current threshold.

[0042] The output of each first comparison circuit serves as the corresponding output of the hardware protection circuit and is connected to one input of the corresponding first logic gate.

[0043] In one possible implementation, the number of first logic gates is greater than 1, and the hardware protection circuit includes: at least one second comparison circuit, at least one third comparison circuit, and multiple second logic gates;

[0044] The number of second comparator circuits is greater than 1, and the number of third comparator circuits is 1; one input terminal of each second comparator circuit receives the reverse current value or the corresponding branch voltage information respectively; one input terminal of the third comparator circuit receives the DC bus voltage information; the two input terminals of the second logic gate are respectively connected to the output terminals of the corresponding second comparator circuit and the third comparator circuit.

[0045] Alternatively, the number of second and third comparator circuits is greater than 1. One input terminal of each second comparator circuit receives the reverse current value of the corresponding branch current information; one input terminal of each third comparator circuit receives the corresponding branch voltage information; and the two input terminals of the second logic gate are connected to the output terminals of the corresponding second and third comparator circuits, respectively.

[0046] The other input terminal of the second comparator circuit and the other input terminal of the third comparator circuit respectively receive the corresponding threshold values;

[0047] The output of each second logic gate serves as the corresponding output of the hardware protection circuit and is connected to one input of the corresponding first logic gate.

[0048] In one possible implementation, the number of first logic gates is greater than 1, and the hardware protection circuit includes: at least one second comparison circuit, at least one third comparison circuit, and multiple second logic gates;

[0049] The number of second comparator circuits is greater than 1, and the number of third comparator circuits is 1. One input terminal of each second comparator circuit receives the reverse current value of the corresponding branch current information when the power converter is a centralized photovoltaic inverter system; receives the reverse current value or corresponding branch voltage information when the power converter is a string photovoltaic inverter system; and receives the reverse current value or corresponding power supply voltage information when the power converter is a distributed photovoltaic inverter system. One input terminal of the third comparator circuit receives the DC bus voltage information. The two input terminals of the second logic gate are connected to the output terminals of the corresponding second comparator circuit and the third comparator circuit, respectively.

[0050] Alternatively, the number of both the second and third comparator circuits is greater than 1. One input terminal of each second comparator circuit receives the reverse current value of the corresponding branch current information; one input terminal of each third comparator circuit receives the corresponding branch voltage information when the power converter belongs to a centralized photovoltaic inverter system or a string photovoltaic inverter system, and receives the corresponding power supply voltage information when the power converter belongs to a distributed photovoltaic inverter system; the two input terminals of the second logic gate are respectively connected to the output terminals of the corresponding second comparator circuit and the corresponding third comparator circuit.

[0051] The other input terminal of the second comparator circuit and the other input terminal of the third comparator circuit respectively receive the corresponding threshold values;

[0052] The output of each second logic gate serves as the corresponding output of the hardware protection circuit and is connected to one input of the corresponding first logic gate.

[0053] In one possible implementation, the hardware protection circuit also includes at least one third logic gate;

[0054] One input of the third logic gate is connected to the output of the corresponding first comparator circuit;

[0055] The other input of the third logic gate receives the characterization signal sent by the control module; when the AC side switch of the power converter is open, the characterization signal prevents the hardware protection circuit from outputting a protection signal.

[0056] The output of the third logic gate serves as one output of the hardware protection circuit.

[0057] In one possible implementation, the second logic gate also has another input terminal to receive a characterization signal sent by the control module; when the AC side switch of the power converter is open, the characterization signal causes the hardware protection circuit to not output a protection signal.

[0058] In one possible implementation, the control module is configured to perform threshold comparisons on different types of information in the DC side electrical parameter sampling information, and generate and output a protection signal when the comparison results at each level exceed the corresponding threshold.

[0059] In one possible implementation, the protection system of the power converter further includes: a fourth comparator circuit and at least one fourth logic gate;

[0060] One input of the fourth comparator circuit receives the power supply voltage sampling information from the protection system;

[0061] The other input of the fourth comparator circuit receives the supply voltage threshold.

[0062] The two inputs of the fourth logic gate are connected to the output of the fourth comparator circuit and the output of the corresponding first logic gate, respectively.

[0063] The output of the fourth logic gate is connected to the control terminal of the corresponding excitation fuse on the DC side of the power converter;

[0064] If the power supply voltage sampling information of the protection system is lower than the power supply voltage threshold, the output signal of the fourth comparator circuit will prevent the fourth logic gate from outputting a trigger signal.

[0065] A second aspect of this disclosure provides a protection method for a power converter, applied to a control module in a protection system for a power converter as described in the first aspect or any implementation thereof; the protection method includes:

[0066] Determine whether there is a reverse current value greater than the second current threshold among the reverse current values ​​of each branch current information on the DC side of the power converter.

[0067] If a reverse current value is greater than the second current threshold, it is determined whether the DC branch voltage information or DC bus voltage information of the power converter meets the preset voltage conditions.

[0068] If branch voltage information or DC bus voltage information meets the preset voltage conditions, it is determined that an external short-circuit fault has occurred on the DC side of the power converter, and a protection signal is generated and output.

[0069] In one possible implementation, determining whether the DC bus voltage information meets a preset voltage condition includes:

[0070] Determine whether the average value of the DC bus voltage information within a preset time period is less than the bus voltage threshold.

[0071] If the average value is less than the bus voltage threshold, then the DC bus voltage information is determined to meet the preset voltage conditions.

[0072] In one possible implementation, determining whether the voltage information of each branch meets a preset voltage condition includes:

[0073] Determine whether the voltage information of each branch is less than the branch voltage threshold;

[0074] If a branch voltage is less than the branch voltage threshold, it is determined that a branch voltage meets the preset voltage condition.

[0075] In one possible implementation, determining whether the DC bus voltage information meets a preset voltage condition includes:

[0076] When the power converter is a centralized photovoltaic inverter system, it is determined whether the DC bus voltage information is less than the bus voltage threshold; if the DC bus voltage information is less than the bus voltage threshold, it is determined that the DC bus voltage information meets the preset voltage condition.

[0077] When the power converter belongs to a distributed photovoltaic inverter system or a string photovoltaic inverter system, it is determined whether the DC bus voltage information is greater than the bus voltage threshold; if the DC bus voltage information is greater than the bus voltage threshold, it is determined that the DC bus voltage information meets the preset voltage condition.

[0078] In one possible implementation, when the power converter is a distributed photovoltaic inverter system, the voltage information of the corresponding power supply is used instead of the branch voltage information to determine whether the preset voltage conditions are met.

[0079] Determine whether the voltage information of each power supply meets the preset voltage conditions, including:

[0080] Determine whether the voltage information of each power supply is less than the power supply voltage threshold;

[0081] If the power supply voltage information is lower than the power supply voltage threshold, it is determined that the power supply voltage information meets the preset voltage condition.

[0082] In one possible implementation, after determining that branch voltage information or DC bus voltage information meets a preset voltage condition, the method further includes:

[0083] Determine whether the sum of the positive current values ​​of the current information of the other branches is greater than the third current threshold;

[0084] If the sum of all forward current values ​​is greater than the third current threshold, then the step of determining that an external short-circuit fault has occurred on the DC side of the power converter is executed.

[0085] A third aspect of this disclosure provides a power converter, comprising: a main circuit, a plurality of excitation fuses, a detection module, a controller, and a protection system as described in the first aspect or any implementation thereof; wherein...

[0086] The DC side of the main circuit is connected to the corresponding DC side interface of the power converter through at least one transmission branch; the DC side interface of the power converter is used to connect to the photovoltaic power source.

[0087] At least one of the positive and negative branches of the transmission branch is provided with a corresponding excitation fuse;

[0088] The detection module is configured to sample DC-side electrical parameters of the power converter.

[0089] The main circuit is controlled by the controller;

[0090] The activation fuse is controlled by the protection system.

[0091] In one possible implementation, the control module in the protection system is integrated into the controller, or the control module is independent of the controller.

[0092] In one possible implementation, the main circuit includes: a DC / AC conversion circuit; the DC side of the DC / AC conversion circuit serves as the DC side of the main circuit, and the AC side of the DC / AC conversion circuit serves as the AC side of the main circuit.

[0093] In one possible implementation, the main circuit also includes: at least one DC / DC converter circuit;

[0094] The DC side of the DC / AC converter circuit is connected to the corresponding transmission branch through the DC / DC converter circuit.

[0095] The fourth aspect of this disclosure provides a control device including a processor and a memory, the memory for storing programs, instructions or code, and the processor for executing the programs, instructions or code in the memory to perform a protection method for a power converter as described in the second aspect or any implementation thereof.

[0096] The fifth aspect of this disclosure provides a computer-readable storage medium storing a computer program, which is loaded by a processor to execute a protection method for a power converter as described in the second aspect or any implementation thereof.

[0097] After reading and understanding the accompanying diagrams and detailed descriptions, the other aspects can be understood.

[0098] Brief description of the attached figures

[0099] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0100] Figure 1 is a schematic diagram of a system containing a power converter according to an embodiment of this disclosure;

[0101] Figure 2 is a schematic diagram of the structure of the centralized photovoltaic inverter system provided in the embodiment of this disclosure;

[0102] Figure 3 is a schematic diagram of the structure of the distributed photovoltaic inverter system provided in the embodiment of this disclosure;

[0103] Figure 4 is a schematic diagram of the structure of the string photovoltaic inverter system provided in the embodiment of this disclosure;

[0104] Figure 5 is a schematic diagram of a protection system for a power converter provided in an embodiment of this disclosure;

[0105] Figure 6 is a schematic diagram of another structure of the protection system for the power converter provided in an embodiment of this disclosure;

[0106] Figure 7 is a schematic diagram of another structure of the protection system for the power converter provided in an embodiment of this disclosure;

[0107] Figure 8 is a schematic diagram of another structure of the protection system for the power converter provided in an embodiment of this disclosure;

[0108] Figure 9 is a schematic diagram of another structure of the protection system for the power converter provided in an embodiment of this disclosure;

[0109] Figure 10 is a schematic diagram of another structure of the protection system for the power converter provided in an embodiment of this disclosure;

[0110] Figure 11 is a schematic diagram of another structure of the protection system for the power converter provided in an embodiment of this disclosure;

[0111] Figure 12 is a schematic diagram of another structure of the protection system for the power converter provided in an embodiment of this disclosure;

[0112] Figure 13 is a schematic diagram of another structure of the protection system for the power converter provided in an embodiment of this disclosure;

[0113] Figure 14 is a schematic diagram of another structure of the protection system for the power converter provided in an embodiment of this disclosure;

[0114] Figure 15 is a schematic diagram of another structure of the protection system for the power converter provided in an embodiment of this disclosure;

[0115] Figure 16 is a flowchart of a protection method for a power converter provided in an embodiment of this disclosure;

[0116] Figure 17 is another flowchart of the protection method for a power converter provided in an embodiment of this disclosure;

[0117] Figure 18 is a schematic diagram of a control device provided in an embodiment of this disclosure. Detailed Implementation

[0118] The embodiments of this disclosure are described below with reference to the accompanying drawings. The terminology used in the Description of Embodiments section of this disclosure is for illustrative purposes only and is not intended to limit the scope of this disclosure.

[0119] The embodiments of this disclosure are described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure. It will be understood by those skilled in the art that, with the development of technology and the emergence of new scenarios, the technical solutions provided by the embodiments of this disclosure are also applicable to similar technical problems.

[0120] The terms “first,” “second,” etc., used in this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the description of embodiments of this disclosure. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of units is not necessarily limited to those units, but may include other units not expressly listed or inherent to those processes, methods, products, or apparatuses.

[0121] Figure 1 shows the specific structure of a power converter used as an inverter in a centralized photovoltaic inverter system. The system mainly includes: photovoltaic array, combiner box, inverter and transformer, etc. Due to its IV (current-voltage) characteristics, the photovoltaic modules in the photovoltaic array will continuously have current flowing out when short-circuited. If the connection between the downstream equipment and the photovoltaic modules is not disconnected in time, it will cause damage to the downstream equipment such as cables and inverters.

[0122] Therefore, fuses are generally used for overcurrent protection on the DC side of photovoltaic inverter systems. The photovoltaic industry has established standards for DC-side fuses, specifying a defined fusing time to prevent fuse failure and a defined non-fusing time to prevent malfunctions. This requires the use of gPV (gamma-ray photovoltaic) fuses (where g indicates the fusing capacity range within the photovoltaic power generation system, and PV indicates the application range is the photovoltaic power generation system). However, even with gPV fuses, the fusing process still relies on the fuse's inherent characteristics, resulting in a long breaking time.

[0123] Therefore, this disclosure provides a protection system for a power converter to improve the timeliness of overcurrent protection. The specific solution is as follows:

[0124] The power converter uses excitation fuses instead of regular fuses for overcurrent protection on the DC side. Figure 2 shows an example of a photovoltaic inverter system structure with the addition of excitation fuses. As shown in Figure 2, the power converter mainly includes a DC / AC conversion circuit 01. The DC side (positive terminal DC+, negative terminal DC-) of the DC / AC conversion circuit 01 is connected to corresponding combiner boxes through multiple excitation fuses (FU1+ and FU1-, ..., FUN+ and FUN-). Each combiner box enables the combined connection of multiple photovoltaic strings. Each photovoltaic string can include multiple photovoltaic modules connected in series. Furthermore, when the power converter is used as the inverter in the photovoltaic inverter system, the DC side of the DC / AC conversion circuit 01 can be equipped with a corresponding DC side switch 03, and the AC side of the DC / AC conversion circuit 01 can be equipped with a corresponding AC side switch 04. In addition, unlike the centralized photovoltaic inverter system shown in Figure 2, in practical applications, each combiner box can also be equipped with a corresponding DC / DC conversion circuit (as shown in Figure 3) to form a distributed photovoltaic inverter system; or, the DC side of the DC / AC conversion circuit 01 can also be connected to at least one DC / DC conversion circuit 02 through the DC bus (as shown in Figure 4). In this case, the input terminal of the DC / DC conversion circuit 02 will be connected to multiple excitation fuses through the corresponding DC side switch 03. There is no need to set up a combiner box between each excitation fuse and the photovoltaic string it is connected to, which can form a string photovoltaic inverter system.

[0125] Regardless of the architecture in which the power converter is applied, its protection system can be as shown in Figure 5, including: a hardware protection circuit 10, a control module 20, and at least one first logic gate 30; wherein:

[0126] Both the input terminals of the hardware protection circuit 10 and the control module 20 receive DC-side electrical parameter sampling information from the power converter. For the various structures shown in Figures 2 to 4, the DC side of the power converter is connected to multiple inputs (N inputs are shown as an example in each figure). Each input is connected to the DC side of the DC / AC conversion circuit 01 through a corresponding transmission branch within the power converter. Each transmission branch is equipped with a corresponding excitation fuse (e.g., FU1+ and FU1-, or FUN+ and FUN- as shown in the figures). Each input on the DC side of the power converter can be connected to a corresponding photovoltaic power source, such as at least one photovoltaic string. The DC side of the power converter can also have at least one input for connecting to an energy storage unit, such as at least one battery cluster; this depends on the specific application environment and is within the scope of this disclosure.

[0127] In practical applications, the DC-side electrical parameter sampling information may only include: the current information of each branch on the DC side; the branch current information refers to the current sampling information flowing through the transmission branch (as shown in Figure 5, I1~I...). N (The corresponding one in the middle). Alternatively, the DC-side electrical parameter sampling information may also include at least two of the following types of information: branch current information, DC-side branch voltage information, and DC bus voltage information; wherein, the branch voltage information refers to the voltage sampling information between the positive and negative branches of the transmission branch, and the bus voltage information refers to the bus voltage sampling information between the positive and negative terminals of the DC-side of the DC / AC conversion circuit 01 (as shown in Figures 2 to 4, positive DC+ and negative DC-) (as shown in Figure 5, U). dc For example, for the structures shown in Figures 2 and 3, the DC-side electrical parameter sampling information can include the branch current information I1 to I2 shown in Figure 5. N DC bus voltage information U dc For the structure shown in Figure 4, the DC side electrical parameter sampling information may include: current information and voltage information of each branch, or voltage information of each branch and DC bus voltage information; but it is not limited to this, and these are just some optional examples.

[0128] Specifically, for the various structures shown in Figures 2 to 4, the DC-side electrical parameter sampling information can include only: the current information of each branch on the DC side; this branch current information refers to the current sampling information flowing through the transmission branch (as shown in Figure 5, I1 to I...). N (The corresponding one in the middle). Alternatively, the DC-side electrical parameter sampling information can also include at least two types of information. For example, for the string photovoltaic inverter system shown in Figure 4, the DC-side electrical parameter sampling information can also include at least two of the following types of information: branch current information, DC-side branch voltage information, and DC bus voltage information; wherein, the branch voltage information refers to the voltage sampling information between the positive and negative branches of the transmission branch, and the bus voltage information refers to the bus voltage sampling information between the positive and negative terminals of the DC / AC conversion circuit 01 (as shown in Figure 4, positive DC+ and negative DC-) (as shown in Figure 5, U). dc That is, the DC-side electrical parameter sampling information can include the current information I1 to I2 of each branch shown in Figure 5. N DC bus voltage information U dcIt can also include branch current information and branch voltage information, branch voltage information and DC bus voltage information, or branch current information, branch voltage information and DC bus voltage information. For the distributed photovoltaic inverter system shown in Figure 3, the branch voltage information is the same as the DC bus voltage information. Therefore, the DC side electrical parameter sampling information can also include at least two of the following: branch current information, DC side power supply voltage information, and DC bus voltage information; where power supply voltage information refers to the voltage of the photovoltaic power supply or energy storage unit connected to the input terminal of the corresponding DC / DC converter circuit; that is, the DC side electrical parameter sampling information can include the branch current information I1~I2 shown in Figure 5. N DC bus voltage information U dc It can also include branch current information and power supply voltage information, or it can include power supply voltage information and DC bus voltage information, or it can include branch current information, power supply voltage information, and DC bus voltage information. For the centralized photovoltaic inverter system shown in Figure 2, the branch voltage information is also the same as the DC bus voltage information. Therefore, the DC side electrical parameter sampling information can also include: branch current information, and branch voltage information or DC bus voltage information.

[0129] The two input terminals of the first logic gate 30 are connected to the output terminal of the hardware protection circuit 10 and the output terminal of the control module 20, respectively; the output terminal of the first logic gate 30 is used to connect to the control terminal of the excitation fuse on the DC side of the power converter.

[0130] The hardware protection circuit 10 and the control module 20 are respectively used to perform threshold comparison based on the DC side electrical parameter sampling information, and generate and output protection signals when the DC side electrical parameter sampling information meets the preset protection conditions, so that the first logic gate 30 outputs a trigger signal to control the corresponding excitation fuse to break.

[0131] Specifically, when the DC-side electrical parameter sampling information only includes the current information of each branch, the preset protection condition may include: the reverse current value of each branch current information is greater than the first current threshold; the reverse current value of the branch current information refers to the magnitude of the reverse current flowing through the corresponding transmission branch. For example, assuming a short circuit fault occurs at the first input of the DC side of the power converter, the combiner boxes connected to the other inputs will inject current into the first transmission branch through their respective transmission branches via the parallel connection point of the transmission branches. At this time, the current flowing through the first transmission branch is the reverse current, and the current flowing through the other transmission branches is the forward current; therefore, the preset protection condition specifically means that at least one reverse current flowing through each transmission branch is greater than the first current threshold.

[0132] When the DC-side electrical parameter sampling information includes at least two of the above-mentioned information, the preset protection condition includes at least two of the following conditions: the reverse current value of each branch current information is greater than the first current threshold; the voltage value of each branch voltage information is less than the branch voltage threshold; and the DC bus voltage information is greater than the bus voltage threshold. For example, when the DC-side electrical parameter sampling information includes both branch current information and DC bus voltage information, the preset protection condition includes: the reverse current value of each branch current information is greater than the first current threshold; and the DC bus voltage information is greater than the bus voltage threshold. The line voltage information is greater than the bus voltage threshold; when the DC side electrical parameter sampling information includes branch current information and branch voltage information, the preset protection condition includes: the reverse current value of each branch current information is greater than the first current threshold, and the voltage value of each branch voltage information is less than the branch voltage threshold; when the DC side electrical parameter sampling information includes branch voltage information and DC bus voltage information, the preset protection condition includes: the voltage value of each branch voltage information is less than the branch voltage threshold, and the DC bus voltage information is greater than the bus voltage threshold.

[0133] The above description uses the string photovoltaic inverter system shown in Figure 4 as an example to illustrate the situation when the DC-side electrical parameter sampling information includes at least two of the above-mentioned information. In practical applications, for the centralized photovoltaic inverter system shown in Figure 2, if the DC-side electrical parameter sampling information includes: current information of each branch and voltage information of each branch on the DC side; then the preset protection condition includes: a reverse current value in the reverse current information of each branch is greater than a first current threshold, and a voltage value in the voltage information of each branch is less than a branch voltage threshold; if the DC-side electrical parameter sampling information includes: current information of each branch and DC bus voltage information; then the preset protection condition includes: a reverse current value in the reverse current information of each branch is greater than a first current threshold, and a DC bus voltage information is less than a bus voltage threshold. For the distributed photovoltaic inverter system shown in Figure 3, the preset protection conditions include at least two of the following conditions: the reverse current value of each branch current information is greater than the first current threshold, the voltage value of each power supply voltage information is less than the power supply voltage threshold, and the DC bus voltage information is greater than the bus voltage threshold.

[0134] The specific settings for the DC-side electrical parameter sampling information and the preset protection conditions are not limited and can be determined according to the specific application environment of the protection system. For example, for the structures shown in Figures 2 to 4, only the current threshold comparison can be performed on each reverse current value. To improve the accuracy of overcurrent fault identification, at least two types of information can be used for corresponding threshold comparisons. For example, for the structure shown in Figure 2, both the current threshold comparison on each reverse current value and the voltage threshold comparison on the DC bus voltage information or the voltage information of each branch can be performed. For the structure shown in Figure 3, both the current threshold comparison on each reverse current value and the voltage threshold comparison on the DC bus voltage information or the voltage information of each power supply can be performed; or both the voltage threshold comparison on the voltage information of each power supply and the voltage threshold comparison on the DC bus voltage information can be performed; or the corresponding threshold comparisons can be performed on each of the three types of information separately. For the structure shown in Figure 4, you can perform current threshold comparisons on each reverse current value, as well as voltage threshold comparisons on the DC bus voltage information or the voltage information of each branch; you can also perform voltage threshold comparisons on both the voltage information of each branch and the DC bus voltage information; or you can perform corresponding threshold comparisons on each of the three types of information separately. These are just some optional examples, and actual applications are not limited to these; you can set them according to the specific scenario requirements.

[0135] In practical applications, the same threshold value can be the same or different in different systems, depending on the specific system settings, and no restrictions are imposed here.

[0136] If the hardware protection circuit 10 performs a hardware threshold comparison on the DC-side electrical parameter sampling information and finds that the DC-side electrical parameter sampling information meets the preset protection condition, then the hardware protection circuit 10 will generate and output a protection signal to the corresponding input terminal of the first logic gate 30. If the control module 20 performs a software threshold comparison on the DC-side electrical parameter sampling information and finds that the DC-side electrical parameter sampling information meets the preset protection condition, then the control module 20 will generate and output a protection signal to the corresponding input terminal of the first logic gate 30. Regardless of whether the hardware protection circuit 10 or the control module 20 outputs a protection signal to the first logic gate 30, as long as either of them outputs a protection signal to the first logic gate 30, the first logic gate 30 will output a corresponding trigger signal to the control terminal of the excitation fuse to trigger the breaking control of the excitation fuse.

[0137] In practical applications, the trigger signal can be either a high-level signal or a low-level signal, depending on the specific application environment; no limitation is made here. The following explanation assumes the trigger signal is a high-level signal, meaning the control terminal of the excitation fuse will be triggered and disconnected upon receiving a high-level signal. In this case, to ensure the protection system can output a high-level signal when the DC-side electrical parameter sampling information meets the preset protection conditions, if the protection signal is high, the first logic gate 30 can be an OR gate; if the protection signal is low, the first logic gate 30 can be a NAND gate. No limitation is made here; the specific application environment is acceptable, and all are within the scope of this disclosure.

[0138] The protection system provided in this embodiment can output a trigger signal to the control terminal of the corresponding excitation fuse through the first logic gate 30 when the hardware protection circuit 10 or the control module 20 outputs the protection signal, thereby controlling the corresponding excitation fuse to break and realizing overcurrent protection. This process does not require the traditional fuse to wait for electrical energy to be converted into heat energy and for the temperature to rise to the melting point, thus avoiding the problem of long breaking time of traditional fuses and improving the timeliness of overcurrent protection.

[0139] In addition, photovoltaic DC-side gPV fuses are prone to failure when interrupting small currents. Specifically, this is because the internal temperature of the fuse is too high when there is a small current overcurrent, and the fuse is prone to arcing during interruption, which leads to interruption failure. Moreover, due to the slow interruption time, the fuse cannot be disconnected in time, which will cause the inverter to receive too much reverse power from the grid and damage the power devices.

[0140] As a new type of fuse, the excitation fuse, through certain technical means, can fully meet the gPV fusing time characteristics and achieve full-range protection and rapid external triggering, thus solving the aforementioned problems. However, in practical applications, if the excitation fuse is used for breaking control without external triggering and only self-excited breaking is likely to fail to protect power devices; when using external triggering, false alarms or missed alarms are also prone to occur, resulting in poor protection performance.

[0141] The protection system provided in this embodiment, through rapid hardware comparison in the hardware protection circuit 10, can quickly disconnect the circuit when an overcurrent fault occurs on the DC side, ensuring that the breaking melting point I²t (ampere square seconds) of the excitation fuse is less than the melting point I²t of the power device, thus preventing damage to the power device and avoiding power device failure. Furthermore, through software protection in the control module 20, by setting appropriate thresholds, it can identify overcurrent faults on the DC side at low current levels, i.e., it can identify long-term small-current short circuits, triggering them in advance and achieving faster disconnection control, avoiding the risk of the fuse continuously heating up and causing prolonged disconnection or even disconnection failure. In other words, the protection system provided in this embodiment, through dual triggering of hardware and software protection, achieves redundant protection against overcurrent faults, ensuring no false alarms or missed alarms in all scenarios, and improving the protection effect.

[0142] Based on the previous embodiment, this embodiment provides some optional examples of the specific structure of the protection system. For example, the number of its first logic gate 30 can be one (as shown in Figure 5). In this case, the output terminal of this first logic gate 30 is connected to the control terminal of each excitation fuse on the DC side of the power converter, that is, each excitation fuse will be controlled by the same trigger signal; if an overcurrent fault occurs on the DC side of the power converter, each excitation fuse will be disconnected simultaneously.

[0143] Alternatively, the number of first logic gates 30 can be greater than 1 (as shown in Figure 6). In this case, the output of each first logic gate 30 is connected to the control terminal of the corresponding excitation fuse on the DC side of the power converter. That is, each excitation fuse is controlled by a corresponding trigger signal (one of the trigger signals #1 to #N shown in Figure 6). Referring to Figure 6, the two inputs of each first logic gate 30 are connected to the corresponding output of the hardware protection circuit 10 and the corresponding output of the control module 20, respectively. Furthermore, if the hardware protection circuit 10 or the control module 20 detects an overcurrent fault in any transmission branch on the DC side, it can output a protection signal to the corresponding first logic gate 30 through its own corresponding output terminal, enabling this first logic gate 30 to control the excitation fuse in the corresponding transmission branch to trip. Additionally, Figure 6 shows N transmission branches on the DC side of the power converter, and the DC side electrical parameter sampling information includes the current information I1 to I... N DC bus voltage information U dc This is just an example; in actual applications, it is not limited to this. The DC side electrical parameter sampling information can take various forms as described in the previous embodiment, all of which are within the protection scope of this disclosure.

[0144] In addition, the hardware protection circuit 10 in this protection system can be implemented in various specific forms, such as:

[0145] In one example, when the number of first logic gates 30 is 1, the hardware protection circuit 10 may include, as shown in FIG7, a first comparison circuit 101. The two inputs of the first comparison circuit 101 receive the maximum reverse current value of each branch current information and a first current threshold I, respectively. ref In one scenario, the first logic gate 30 is an OR gate, the non-inverting input of the first comparison circuit 101 receives the maximum reverse current value of each branch current information, and the inverting input of the first comparison circuit 101 receives the first current threshold I. ref The output of the first comparator circuit 101 serves as the output of the hardware protection circuit 10.

[0146] Assume the power converter has N transmission branches on the DC side, where N is a positive integer, and the current information of each branch is denoted as I1 to I... N The reverse current values ​​can be denoted as I'1 to I', respectively. N The maximum value of this reverse current is Max(I'1, ..., I'). N In practical applications, the reverse current values ​​I'1 to I' can be set. N The corresponding diodes output to the non-inverting input of the first comparator circuit 101, thereby maximizing the maximum value of each reverse current value, Max(I'1, ..., I'). N The output can be sent to the non-inverting input of the first comparator circuit 101, but it is not limited to this. Other methods in related technologies can also be used to obtain the maximum value of the reverse current Max(I'1, ..., I'). N ).

[0147] In the structure shown in Figure 7, when the maximum value of the reverse current Max(I'1, ..., I') is reached... N () greater than the first current threshold I ref When the first comparison circuit 101 outputs a high-level signal, it is transmitted to the first logic gate 30 as a protection signal, causing the first logic gate 30 to output a high-level trigger signal.

[0148] In another example, when the number of first logic gates 30 is 1, the hardware protection circuit 10 can also be as shown in Figure 8, including: a second comparison circuit 102, a third comparison circuit 103, and a second logic gate 104. One input of the second comparison circuit 102 receives the maximum reverse current value Max(I'1, ..., I') of each branch current information. N ), the minimum voltage value of each branch and the DC bus voltage information U dcOne of the following; another input of the second comparison circuit 102 receives a corresponding threshold; the output of the second comparison circuit 102 is connected to one input of the second logic gate 104; one input of the third comparison circuit 103 receives the maximum reverse current value Max(I'1, ..., I') of each branch current information. N ), the minimum voltage value of each branch and the DC bus voltage information U dc Another type; another input terminal of the third comparison circuit 103 receives the corresponding threshold; the output terminal of the third comparison circuit 103 is connected to another input terminal of the second logic gate 104; the output terminal of the second logic gate 104 serves as the output terminal of the hardware protection circuit 10.

[0149] In one scenario, as shown in Figure 8, the first logic gate 30 is an OR gate, and the non-inverting input of the second comparator circuit 102 receives the maximum value of the reverse current, Max(I'1, ..., I'). N The inverting input of the second comparator circuit 102 receives the first current threshold I. ref The inverting input of the third comparator circuit 103 receives the DC bus voltage information U. dc The non-inverting input of the third comparator circuit 103 receives the bus voltage threshold U. ref The second logic gate 104 is an AND gate; however, the example shown in Figure 8 is only one option. Other settings can be used in actual applications, depending on the circuit structure of the system in which the power converter is located.

[0150] In the structure shown in Figure 8, when the maximum value of the reverse current Max(I'1, ..., I') is reached... N () greater than the first current threshold I ref And the DC bus voltage information U dc Less than the bus voltage threshold U ref When the second logic gate 104 outputs a high-level signal, it is transmitted to the first logic gate 30 as a protection signal, causing the first logic gate 30 to output a high-level trigger signal.

[0151] For the power converter in the centralized photovoltaic inverter system shown in Figure 2, under the structure shown in Figure 8, the information received by the two comparator circuits can be as shown in Figure 8. Alternatively, the two input terminals of its third comparator circuit 103 can also receive the minimum voltage value and corresponding threshold value of each branch voltage information, respectively. For the power converter in the string photovoltaic inverter system shown in Figure 4, under the structure shown in Figure 8, one input terminal of the second comparator circuit 102 receives the maximum reverse current value Max(I'1, ..., I') of each branch current information. N ), the minimum voltage value of each branch and the DC bus voltage information U dcOne of them; another input terminal of the second comparison circuit 102 receives a corresponding threshold; one input terminal of the third comparison circuit 103 receives the maximum value of the reverse current value Max(I'1, ..., I') of each branch current information. N ), the minimum voltage value of each branch and the DC bus voltage information U dc Another type; the other input of the third comparison circuit 103 receives the corresponding threshold. For the power converter in the distributed photovoltaic inverter system shown in Figure 3, in the structure shown in Figure 8, one input of the second comparison circuit 102 receives the maximum reverse current value Max(I'1, ..., I') of each branch current information. N ), the minimum voltage values ​​of each power supply voltage information and the DC bus voltage information U dc One of them; another input terminal of the second comparison circuit 102 receives a corresponding threshold; one input terminal of the third comparison circuit 103 receives the maximum value of the reverse current value Max(I'1, ..., I') of each branch current information. N ), the minimum voltage values ​​of each power supply voltage information and the DC bus voltage information U dc Another type; the other input of the third comparison circuit 103 receives the corresponding threshold.

[0152] In another example, when the number of first logic gates 30 is greater than 1, the hardware protection circuit 10 may include, as shown in FIG9, a plurality of first comparison circuits 101; wherein, one input terminal of each first comparison circuit 101 receives the reverse current value of the corresponding branch current information (as shown by I'1 to I' in FIG9). N (corresponding to one of them); the other input terminal of each first comparison circuit 101 receives the first current threshold I respectively. ref The output of each first comparison circuit 101 serves as the corresponding output of the hardware protection circuit 10 and is connected to one input of the corresponding first logic gate 30.

[0153] In one scenario, as shown in Figure 9, the first logic gate 30 is an OR gate, and the non-inverting inputs of each first comparison circuit 101 receive the corresponding reverse current values ​​(as shown by I'1 to I' in the figure). N (corresponding to one of them), the inverting input terminal of each first comparison circuit 101 receives the first current threshold I respectively. ref .

[0154] In the structure shown in Figure 9, when the reverse current values ​​I'1 to I' N There exists at least one reverse current value greater than the first current threshold I. refWhen this occurs, the corresponding first comparator circuit 101 outputs a high-level signal, which is transmitted as a protection signal to the first logic gate 30 connected to the first comparator circuit 101. The trigger signal output by the first logic gate 30 then controls the excitation fuse in the corresponding transmission branch to trip. For example, when I'1>I... ref When the first comparator circuit 101 at the top of Figure 9 outputs a trigger signal #1 through the first logic gate 30 in the upper right corner, it controls the excitation fuse in the first transmission branch on the DC side of the power converter to break.

[0155] In another example, when the number of first logic gates 30 is greater than 1, the hardware protection circuit 10 can be as shown in Figure 10, including: at least one second comparison circuit 102, at least one third comparison circuit 103, and multiple second logic gates 104. Specifically, the number of second comparison circuits 102 can be set to be greater than 1, and the number of third comparison circuits 103 can be 1; in this case, one input terminal of each second comparison circuit 102 receives the reverse current value of the corresponding branch current information (as shown in Figure I). ’ 1 to I' N The second logic gate 104 receives the DC bus voltage information (corresponding to one of the branches in the circuit); one input of the third comparison circuit 103 receives the DC bus voltage information; the two inputs of the second logic gate 104 are respectively connected to the outputs of the corresponding second comparison circuit 102 and the third comparison circuit 103. Alternatively, the number of second comparison circuits 102 and third comparison circuits 103 can be greater than 1. In this case, one input of each second comparison circuit 102 receives the reverse current value of the corresponding branch current information; one input of each third comparison circuit 103 receives the corresponding branch voltage information; the two inputs of the second logic gate 104 are respectively connected to the outputs of the corresponding second comparison circuit 102 and the corresponding third comparison circuit 103. In addition, the other input of the second comparison circuit 102 and the third comparison circuit 103 receives the corresponding threshold; the output of each second logic gate 104 serves as the corresponding output of the hardware protection circuit 10 and is connected to one input of the corresponding first logic gate 30.

[0156] In one scenario, as shown in Figure 10, the first logic gate 30 is an OR gate, the number of second comparator circuits 102 is greater than 1, the number of third comparator circuits 103 is 1, and the non-inverting input of each second comparator circuit 102 receives the corresponding reverse current value (as shown by I'1 to I' in the figure). N (corresponding to one of them), the inverting input terminal of each second comparator circuit 102 receives the first current threshold I. ref The inverting input of the third comparator circuit 103 receives the DC bus voltage information U. dc The non-inverting input of the third comparator circuit 103 receives the bus voltage threshold U. refThe second logic gate 104 is an AND gate; however, the example shown in Figure 10 is only an optional one. Other settings can be used in actual applications, depending on the circuit structure of the system in which the power converter is located.

[0157] In the structure shown in Figure 10, when the reverse current values ​​I'1 to I' N There exists at least one reverse current value greater than the first current threshold I. ref And the DC bus voltage information U dc Less than the bus voltage threshold U ref When this occurs, the corresponding second logic gate 104 outputs a high-level signal, which is transmitted as a protection signal to the first logic gate 30 connected to the second logic gate 104. This trigger signal output by the first logic gate 30 then controls the excitation fuse in the corresponding transmission branch to trip. For example, when I'1>I... ref AndU dc ref When the second logic gate 104 at the top of Figure 10 outputs a trigger signal #1 through the first logic gate 30 in the upper right corner, it controls the excitation fuse in the first transmission branch on the DC side of the power converter to break.

[0158] For the power converter in the centralized photovoltaic inverter system shown in Figure 2, under the structure shown in Figure 10, the information received by the two comparison circuits can be as shown in Figure 10. For the power converter in the string photovoltaic inverter system shown in Figure 4, under the structure shown in Figure 10, the non-inverting input terminals of each second comparison circuit 102 receive the corresponding reverse current values ​​(as shown by I'1 to I' in the figure). N The corresponding input terminal of each second comparison circuit 102 receives the corresponding threshold value (one of the corresponding values ​​in the circuit) or the corresponding branch voltage information; the other input terminal of each second comparison circuit 102 receives the corresponding threshold value. For the power converter in the distributed photovoltaic inverter system shown in Figure 3, under the structure shown in Figure 10, the non-inverting input terminal of each second comparison circuit 102 receives the corresponding reverse current value (I'1 to I' as shown in the figure). N The corresponding input of each second comparison circuit 102 receives the corresponding threshold value. Additionally, when the number of both the second comparison circuit 102 and the third comparison circuit 103 is greater than one, one input of each second comparison circuit 102 receives the reverse current value of the corresponding branch current information; one input of each third comparison circuit 103 receives the corresponding branch voltage information when the power converter belongs to the centralized photovoltaic inverter system shown in Figure 2 or the string photovoltaic inverter system shown in Figure 4, and receives the corresponding power supply voltage information when the power converter belongs to the distributed photovoltaic inverter system shown in Figure 3; at this time, the two inputs of each second logic gate 104 are connected to the output of the corresponding second comparison circuit 102 and the output of the corresponding third comparison circuit 103, respectively.​

[0159] Figures 7 to 10 all illustrate the first logic gate 30 using an OR gate as an example. In this case, for each comparison circuit that performs current comparison, such as the first comparison circuit 101 and the second comparison circuit 102 mentioned above, the input terminals are all set as follows: the non-inverting input terminal receives the corresponding information in the DC side electrical parameter sampling information, while the inverting input terminal receives the corresponding threshold. For each comparison circuit that performs voltage comparison, such as the third comparison circuit 103 mentioned above, the input terminals are all set as follows: the inverting input terminal receives the corresponding information in the DC side electrical parameter sampling information, while the non-inverting input terminal receives the corresponding threshold. And the second logic gate 104 is an AND gate. In the structures shown in Figures 8 and 10, if the input terminals of either the second comparison circuit 102 or the third comparison circuit 103 are swapped, the second logic gate 104 can be implemented using an XOR gate; if the input terminals of both the second comparison circuit 102 and the third comparison circuit 103 are swapped, the second logic gate 104 can be implemented using a NOR gate. In both variations, a high-level protection signal and a high-level trigger signal can be achieved, and the above-mentioned interruption control can also be realized.

[0160] Furthermore, if the first logic gate 30 is a NAND gate, the protection signal output by the hardware protection circuit 10 will become a low-level signal. At this time, the first comparison circuit 101 in Figures 7 and 9 will both change so that the inverting input receives the corresponding information in the DC-side electrical parameter sampling information, while the non-inverting input receives the corresponding threshold. In the structure shown in Figures 8 and 10, the second logic gate 104 can be changed to be implemented using a NAND gate without changing the input settings of the second comparison circuit 102 and the third comparison circuit 103; the input settings of either the second comparison circuit 102 or the third comparison circuit 103 can be swapped, and the second logic gate 104 can be changed to be implemented using an XNOR gate; the input settings of both the second comparison circuit 102 and the third comparison circuit 103 can be swapped, and the second logic gate 104 can be changed to be implemented using an OR gate. These will not be described and illustrated one by one here. The specific settings can be determined according to the application environment, and all are within the protection scope of this disclosure.

[0161] The various hardware protection circuits 10 provided in this embodiment can all realize fast hardware comparison of the corresponding sampling information, thereby realizing fast disconnection of the corresponding excitation fuse and avoiding power device failure.

[0162] Based on the above embodiments, this embodiment provides some other optional examples of the specific structure of the hardware protection circuit 10 in the protection system, such as:

[0163] Referring to Figure 11 or Figure 12, where Figure 11 is a representation based on Figure 7 and Figure 12 is a representation based on Figure 9; that is, when only current threshold comparison is performed, the hardware protection circuit 10 may further include: at least one third logic gate 105; one input of the third logic gate 105 is connected to the output of the corresponding first comparison circuit 101; the other input of the third logic gate 105 receives a characterization signal sent by the control module 20. When the AC side switch of the power converter is open, this characterization signal prevents the hardware protection circuit 10 from outputting a protection signal. The output of the third logic gate 105 serves as one output of the hardware protection circuit 10.

[0164] Referring to Figure 13 or Figure 14, where Figure 13 is a representation based on Figure 8 and Figure 14 is a representation based on Figure 10; that is, when comparing at least two of the current and two voltage thresholds, the second logic gate 104 may also have another input terminal to receive the characterization signal sent by the control module 20; similarly, when the AC side switch of the power converter is open, the characterization signal causes the hardware protection circuit 10 not to output a protection signal.

[0165] That is, when the control module 20 detects that the DC side switch and AC side switch of the power converter are closed, it determines that the current state of the power converter is a hardware-triggered state, that is, the hardware protection circuit 10 can provide overcurrent protection for the DC side of the power converter; when the control module 20 detects that the AC side switch is open, it determines that the current state of the power converter is not a hardware-triggered state, that is, the hardware protection circuit 10 does not work and does not provide protection against overcurrent faults on the DC side of the power converter.

[0166] In one scenario, as shown in Figures 11 to 14, both the second logic gate 104 and the third logic gate 105 are AND gates. The characterization signal is high when both the DC-side switch and the AC-side switch of the power converter are closed, and low when the AC-side switch is open.

[0167] Taking the structure shown in Figure 13 as an example, when the maximum value of the reverse current is Max(I'1, ..., I'), N () greater than the first current threshold I ref The DC bus voltage information U dc Less than the bus voltage threshold U ref When the control module 20 recognizes that the current state of the power converter is a hardware trigger state and outputs a high-level characterization signal, the second logic gate 104 will output a high-level signal and transmit it to the first logic gate 30 as a protection signal, so that the first logic gate 30 outputs a trigger signal.

[0168] In practical applications, for the structures shown in Figures 11 and 12, if at least one of the following is changed: the input terminal setting of the first comparison circuit 101, the implementation of the first logic gate 30, or the level setting of the characterizing signal, then by changing the implementation of the third logic gate 105, the control module 20 can control whether the hardware protection circuit 10 can function after identifying the current state of the power converter. Similarly, in the structures shown in Figures 13 and 14, the input terminal setting of the second comparison circuit 102, the input terminal setting of the third comparison circuit 103, the implementation of the second logic gate 104, the implementation of the first logic gate 30, and the level setting of the characterizing signal can all be changed according to the actual application environment, as long as the protection system can achieve the hardware triggering function in the hardware triggering state; various implementations will not be described in detail, and are all within the protection scope of this disclosure.

[0169] The protection system provided in this embodiment can quickly disconnect the DC-side fault through hardware protection when both the DC-side switch and the AC-side switch of the power converter are closed, thus preventing the power device from failing.

[0170] Based on the above embodiments, this embodiment provides some specific examples of the implementation of other parts of the protection system. For example, its control module 20 can be used to perform threshold comparisons on different types of information in the DC side electrical parameter sampling information, and generate and output protection signals when the comparison results at each level exceed the corresponding thresholds.

[0171] In one example, the control module 20 can first perform a current threshold comparison, and then perform a voltage threshold comparison; that is, first compare the current information I1 to I2 of each branch. N The reverse current values ​​are compared with a second current threshold, and if at least one reverse current value is greater than the second current threshold, the DC bus voltage information U is then compared. dc With bus voltage threshold U ref The voltage values ​​of each branch can be compared, or the voltage values ​​of each branch can be compared with the branch voltage threshold. If any of the compared voltage values ​​exceeds the corresponding voltage threshold, a protection signal can be generated and output. This second current threshold can be compared with the aforementioned first current threshold I. refThe voltage values ​​can be the same or different, depending on the specific application environment, and all are within the scope of protection of this disclosure. Specifically, in the application scenario of a centralized photovoltaic inverter system, the situation where the voltage value being compared exceeds the corresponding voltage threshold can refer to: the DC bus voltage information being less than the bus voltage threshold, or the voltage value of each branch voltage information being less than the branch voltage threshold. In the application scenario of a string photovoltaic inverter system, the situation where the voltage value being compared exceeds the corresponding voltage threshold can refer to: the DC bus voltage information being greater than the bus voltage threshold, or the voltage value of each branch voltage information being less than the branch voltage threshold. In the application scenario of a distributed photovoltaic inverter system, since the voltage of each branch, i.e., the output voltage of each DC / DC converter circuit, is equal to the DC bus voltage, the power supply voltage, i.e., the input voltage of the DC / DC converter circuit, can be used to replace the branch voltage in the other two application scenarios; in this case, the situation where the voltage value being compared exceeds the corresponding voltage threshold can refer to: the DC bus voltage information being greater than the bus voltage threshold, or the voltage value of each power supply voltage information being less than the power supply voltage threshold.

[0172] In another example, the control module 20 can also first perform a reverse current threshold comparison, then a voltage threshold comparison, and finally a forward current threshold comparison; for example, first compare the current information I1 to I2 of each branch. N The reverse current values ​​are respectively compared with the first current threshold I ref The comparison is performed, and if at least one reverse current value is greater than the first current threshold I... ref In the case of DC bus voltage information Udc or voltage information of each branch, the voltage value is compared with the corresponding voltage threshold. If there is a case where the voltage value being compared is less than the corresponding voltage threshold, then the sum of the forward current values ​​of each branch current information whose reverse current value is not greater than the first current threshold Iref is compared with another current threshold. If the sum of the forward current values ​​is greater than this current threshold, a protection signal is generated and output.

[0173] In practical applications, the hierarchical comparison performed by the control module 20 can also be performed in other sequences. For example, threshold comparisons can be performed first on the voltage information of each branch, then on the DC bus voltage information, and subsequently, a threshold comparison of the sum of forward current values ​​can be added. Alternatively, more levels of comparison can be used; these will not be listed here, but are all within the scope of protection disclosed herein. Various software protection schemes that implement multi-level comparisons can improve the accuracy of overcurrent protection and avoid false triggering. Moreover, by using software judgment and setting appropriate thresholds, low-current conditions can be accurately and quickly identified, thereby achieving timely interruption at low-current conditions and avoiding the risk of fuses continuously heating up and prolonged interruption.

[0174] In addition, the above-mentioned judgment process of the control module 20 can be applied to various scenarios, including the scenario where the AC side switch of the power converter is open; that is, when the AC side switch is closed, since the hardware protection speed is faster, the protection system mainly relies on the hardware protection function to realize the rapid disconnection in the event of a DC side fault, so as to avoid the failure of power devices; while when the AC side switch is open, the software protection function can be used to realize the DC side overcurrent protection, including the timely disconnection in the event of a low current.

[0175] Furthermore, when the power converter is in SVG (Static Var Generator) operation mode, its DC side switch is open. At this time, the control module 20 can be set not to perform overcurrent fault identification and protection, thereby reducing the workload of the control module 20.

[0176] Based on the above embodiments, the protection system may further include, as shown in FIG15 (based on FIG13 as an example): a fourth comparison circuit 40 and at least one fourth logic gate 50; wherein, one input terminal of the fourth comparison circuit 40 receives the power supply voltage sampling information U of the protection system. fu The other input of the fourth comparator circuit 40 receives the supply voltage threshold U. ref2 The two input terminals of the fourth logic gate 50 are connected to the output terminal of the fourth comparator circuit 40 and the output terminal of the corresponding first logic gate 30, respectively; the output terminal of the fourth logic gate 50 is connected to the control terminal of the corresponding excitation fuse on the DC side of the power converter.

[0177] The input configuration of the fourth comparator circuit 40 and the specific implementation of the fourth logic gate 50 can be selected according to the actual application environment. For example, as shown in Figure 15, the fourth logic gate 50 can be configured as an AND gate, and the non-inverting input of the fourth comparator circuit 40 can be configured to receive the power supply voltage sampling information U of the protection system. fu The inverting input of the fourth comparator circuit 40 receives the supply voltage threshold U. ref2 Under this structure, when U fu ref2 When the voltage is low, it indicates that the power supply voltage of the protection system is low. This power supply voltage typically originates from the photovoltaic unit or the DC bus of the power converter. Therefore, a low power supply voltage corresponds to situations with weak sunlight, such as when the power converter is powered on or off. And in U... fu ref2 ​​When the power supply voltage of the protection system is normal, the fourth comparator circuit 40 outputs a low-level signal. At this time, regardless of whether the first logic gate 30 outputs a trigger signal, after passing through the AND logic of the fourth logic gate 50, it will become a low-level signal, thus preventing the corresponding excitation fuse from tripping and avoiding false triggering during power-up and power-down. Only when the power supply voltage of the protection system is normal can the trigger signal output by the first logic gate 30 be output to the control terminal of the corresponding excitation fuse through the fourth logic gate 50.

[0178] That is, the protection system provided in this embodiment can provide a hardware shielding signal for overcurrent protection through the comparison of the fourth comparison circuit 40, thereby preventing false alarms for overcurrent faults.

[0179] In addition, the input terminal configuration of the fourth comparison circuit 40 and the specific implementation of the fourth logic gate 50 can also adopt other configurations, as long as the trigger signal during power-on and power-off can be hardware shielded through the above principle, which is within the protection scope of this disclosure.

[0180] Another embodiment of this disclosure provides a protection method for a power converter, applied to the control module of a protection system for a power converter as described in any of the above embodiments; the structure and principle of the protection system can be found in the above embodiments, and will not be repeated here.

[0181] As shown in Figure 16, the protection method includes:

[0182] S101. Determine whether there is a reverse current value greater than the second current threshold among the reverse current values ​​of each branch current information on the DC side of the power converter.

[0183] As described in the above embodiments, the second current threshold in software protection and the first current threshold in hardware protection can be the same or different, depending on the specific application environment, and both are within the protection scope of this disclosure.

[0184] If the reverse current value is greater than the second current threshold, the external short-circuit condition is met, and S102 can be executed. Otherwise, continue executing S101.

[0185] S102. Determine whether the DC branch voltage information or DC bus voltage information of the power converter meets the preset voltage conditions.

[0186] In one example, S102 may specifically include: determining whether the average value of the DC bus voltage information within a preset time period is less than a bus voltage threshold; if the average value is less than the bus voltage threshold, then determining that the DC bus voltage information meets the preset voltage condition. The value of the preset time period is not limited and depends on the specific application environment. This example illustrates the specific process of determining whether the DC bus voltage information meets the preset voltage condition in S102, specifically for a centralized photovoltaic inverter system.

[0187] In practical applications, when the power converter is a centralized photovoltaic inverter system, determining whether the DC bus voltage information meets the preset voltage condition in S102 can specifically include: determining whether the DC bus voltage information is less than a bus voltage threshold; if the DC bus voltage information is less than the bus voltage threshold, then the DC bus voltage information is determined to meet the preset voltage condition. However, when the power converter is a distributed photovoltaic inverter system or a string photovoltaic inverter system, determining whether the DC bus voltage information meets the preset voltage condition in S102 can specifically include: determining whether the DC bus voltage information is greater than a bus voltage threshold; if the DC bus voltage information is greater than the bus voltage threshold, then the DC bus voltage information is determined to meet the preset voltage condition.

[0188] Alternatively, S102 may also include: determining whether the voltage information of each branch is less than the branch voltage threshold; if there is a branch voltage information less than the branch voltage threshold, then determining that there is a branch voltage information that meets the preset voltage condition.

[0189] Alternatively, if the power converter is a distributed photovoltaic inverter system, the corresponding power supply voltage information can be used instead of the branch voltage information to determine whether the preset voltage condition is met. In this case, S102 may also include: determining whether the power supply voltage information of each power supply is less than the power supply voltage threshold; if there is power supply voltage information less than the power supply voltage threshold, it is determined that there is power supply voltage information that meets the preset voltage condition.

[0190] The judgment process of S102 can be referred to in the above embodiments. The specific selection depends on the specific application environment, and all are within the protection scope of this disclosure.

[0191] In practical applications, there may be situations where two voltage information exceed their respective voltage thresholds. However, as long as it is determined that one of the voltage information exceeds its corresponding voltage threshold, it can be determined that the preset voltage condition is met.

[0192] If a branch voltage information meets the preset voltage condition, or the DC bus voltage information meets the preset short-circuit voltage condition, then execute S103. For example, if the preset voltage condition is determined based on the branch voltage information and a branch voltage information meets the preset voltage condition, or if the preset voltage condition is determined based on the power supply voltage information and a power supply voltage information meets the preset voltage condition, or if the preset voltage condition is determined based on the DC bus voltage information and the DC bus voltage information meets the preset voltage condition, then it is determined that there is corresponding voltage information that meets the preset voltage condition, and S103 can be executed. Otherwise, continue executing S102.

[0193] S103. Determine if an external short-circuit fault has occurred on the DC side of the power converter, generate and output a protection signal.

[0194] Furthermore, after S103, if it is determined that there is corresponding voltage information that meets the preset voltage condition, the protection method may also include the following shown in Figure 17:

[0195] S201. Determine whether the sum of the positive current values ​​of the current information of the other branches is greater than the third current threshold.

[0196] If the sum of all positive current values ​​is greater than the third current threshold, it can be determined that an external short circuit has occurred, and S103 will be executed.

[0197] Furthermore, when S103 is executed, the protection signal can be for the transmission branch where the reverse current value is greater than the second current threshold. That is, the protection signal can control the corresponding excitation fuse to break, thereby achieving independent control of each excitation fuse.

[0198] In addition, after S103 is executed, other transmission branches can continue to operate; that is, after the faulty transmission branch is disconnected, the power converter can continue to operate; therefore, after S103, it is possible to return to S101 again to continue overcurrent protection on the DC side of the power converter.

[0199] The protection method provided in this embodiment can identify overcurrent faults on the DC side under low current by setting an appropriate threshold. In other words, it can identify long-term low-current short circuits, trigger them in advance, and thus achieve disconnection control more quickly, avoiding the risk of the fuse continuously heating up and disconnecting for a long time or even failing to disconnect.

[0200] Another embodiment of this disclosure also provides a power converter, as shown in Figures 2 to 4, including: a main circuit, multiple excitation fuses FU1+ to FUN-, a detection module, a controller (not shown in the figures), and a protection system for the power converter as described in any of the above embodiments; wherein:

[0201] The DC side of the main circuit is connected to the corresponding DC side interface of the power converter via at least one transmission branch. At least one DC side interface of the power converter is used to connect to a photovoltaic (PV) power source. This PV power source may include one PV string or at least two PV strings connected in parallel. Each PV string may include one PV module or at least two PV modules connected in series. In practical applications, each DC side interface of the power converter can be fully connected, meaning each interface is connected to a corresponding PV power source, or it may not be fully connected. When not fully connected, the interfaces not connected to PV power sources are in a floating state, and can be used to connect either PV power sources or energy storage power sources, depending on the specific application environment; all of these are within the scope of this disclosure.

[0202] In practical applications, as shown in Figures 2 to 4, the main circuit includes at least: a DC / AC conversion circuit 01; the DC side of the DC / AC conversion circuit 01 serves as the DC side of the main circuit, and the AC side of the DC / AC conversion circuit 01 serves as the AC side of the main circuit. In this case, the power converter can function as an inverter, with its AC side used to connect to at least one of the power grid and the load. Furthermore, the DC side of the DC / AC conversion circuit 01 can be equipped with a corresponding DC side switch 03, and the AC side of the DC / AC conversion circuit 01 can be equipped with a corresponding AC side switch 04.

[0203] In addition, as shown in Figure 4, the main circuit may also include at least one DC / DC converter circuit 02; in this case, the DC side of the DC / AC converter circuit 01 is connected to the corresponding transmission branch through the DC / DC converter circuit 02.

[0204] At least one of the positive and negative branches of the transmission branch is provided with a corresponding excitation fuse; Figures 2 to 4 show examples of the positive and negative branches being provided with corresponding excitation fuses respectively. In actual applications, the corresponding excitation fuse may also be provided in only one of the positive and negative branches; it depends on the specific application environment, and all are within the protection scope of this disclosure.

[0205] This detection module is used to sample the DC-side electrical parameters of the power converter. As shown in the above embodiment, the DC-side electrical parameter sampling information may only include the current information of each branch on the DC side. In this case, the detection module may be a current sensor installed in each transmission branch (as shown in the small circles on one side of each excitation fuse in the figure). Alternatively, the DC-side electrical parameter sampling information may also include at least two of the following types of information: branch current information, DC-side branch voltage information, and DC bus voltage information; wherein, the branch voltage information refers to the voltage sampling information between the positive and negative branches of the transmission branch, and the bus voltage information refers to the bus voltage sampling information between the positive and negative terminals of the DC / AC conversion circuit 01 (as shown in Figures 2 to 4, positive DC+ and negative DC-) (as shown in Figure 5, U). dc )

[0206] The main circuit is controlled by the controller; that is, the controller can control the operation of the main circuit. For the specific control principle, please refer to the relevant technology, which will not be elaborated here.

[0207] Each excitation fuse is controlled by this protection system. The structure and principle of this protection system can be found in the above embodiments, and will not be repeated here.

[0208] In practical applications, the control module in this protection system can be integrated into the controller. That is, the controller can be responsible for both the operation control of the main circuit and the software protection against DC-side overcurrent faults in the main circuit. Alternatively, the control module can be independent of the controller; that is, a separate control module capable of implementing software protection, such as a Microcontroller Unit, can be set up outside the controller. No limitation is made here; it depends on the specific application environment, and all are within the scope of this disclosure.

[0209] The power converter provided in this embodiment, by employing this protection system, can achieve rapid disconnection through hardware protection when an overcurrent fault occurs on the DC side. This ensures that the breaking melting point of the excitation fuse is lower than the melting point of the power device, preventing damage to the power device and avoiding power device failure. Furthermore, it can identify overcurrent faults on the DC side at low current levels through software protection, avoiding the risk of the fuse continuously heating up and breaking for an extended period, or even failing to break. In other words, this embodiment achieves redundant protection against overcurrent faults through dual triggering of hardware and software protection, ensuring no false alarms or missed alarms across all scenarios and improving protection effectiveness.

[0210] Another embodiment of this disclosure also provides a control device, as shown in FIG18, which may include a memory 11 and a processor 12. The memory 11 is used to store programs, instructions, or code. When the programs, instructions, or code stored in the memory 11 are executed by the processor 12, the processor 12 can be used to execute the protection method of the power converter described in any of the above embodiments.

[0211] The control device can be connected to the power converter, specifically the processor 12 is connected to the power converter, thereby enabling the processor 12 to control the excitation fuse in the power converter to break; the memory 11 can also store data, such as various thresholds involved in the above embodiments.

[0212] The memory 11 can specifically be RAM (random access memory), flash memory, ROM (read only memory), EPROM (Electronic Programmable ROM, a type of non-volatile read-only memory), registers, hard disks, removable disks, etc.

[0213] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this disclosure is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, DSL (digital subscriber line)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available media can be magnetic media, such as floppy disks, hard disks, and magnetic tapes; or, the available media can be semiconductor media, such as SSDs (solid state disks); the available media can also be other media, without limitation.

[0214] Another embodiment of this disclosure provides a computer-readable storage medium storing a computer program that is loaded by a processor to execute the power converter protection method as described in any of the above embodiments.

[0215] That is, the computer-readable storage medium is used to store the methods or algorithms provided in the above embodiments. Specifically, it can be RAM, flash memory, ROM, EPROM, registers, hard disk, removable disk, or any other form of storage medium in the art.

[0216] Similar or identical parts between the various embodiments in this disclosure can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the description of the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment solution according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0217] Those skilled in the art will also recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this disclosure.

[0218] The above description of the disclosed embodiments shows that the features described in the various embodiments of this disclosure can be substituted for or combined with each other, enabling those skilled in the art to implement or use this disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A protection system for a power converter, wherein, include: Hardware protection circuit, control module, and at least one first logic gate; Both the input terminal of the hardware protection circuit and the input terminal of the control module receive DC-side electrical parameter sampling information from the power converter. The two input terminals of the first logic gate are respectively connected to the output terminal of the hardware protection circuit and the output terminal of the control module; The output of the first logic gate is used to connect to the control terminal of the excitation fuse on the DC side of the power converter; The hardware protection circuit and the control module are respectively configured to perform threshold comparison based on the DC side electrical parameter sampling information, and generate and output a protection signal when the DC side electrical parameter sampling information meets the preset protection conditions, so that the first logic gate outputs a trigger signal to control the corresponding excitation fuse to break.

2. The protection system for the power converter according to claim 1, wherein, The number of the first logic gate is 1, and the output of the first logic gate is connected to the control terminal of each excitation fuse on the DC side of the power converter. Alternatively, the number of the first logic gates is greater than 1, the output of each first logic gate is connected to the control terminal of the corresponding excitation fuse on the DC side of the power converter, and the two inputs of the first logic gate are connected to the corresponding output of the hardware protection circuit and the corresponding output of the control module.

3. The protection system for the power converter according to claim 2, wherein, The DC-side electrical parameter sampling information includes: current information of each branch on the DC side; the preset protection condition includes: the reverse current value of each branch current information is greater than a first current threshold. Alternatively, the DC-side electrical parameter sampling information includes at least two of the following: branch current information, DC-side branch voltage information, and DC bus voltage information; the preset protection conditions include at least two of the following conditions: the reverse current value of each branch current information is greater than a first current threshold, the voltage value of each branch voltage information is less than a branch voltage threshold, and the DC bus voltage information is greater than a bus voltage threshold.

4. The protection system for the power converter according to claim 2, wherein, When the power converter is a centralized photovoltaic inverter system, the DC-side electrical parameter sampling information includes: the current information of each branch and the voltage information of each branch on the DC side; the preset protection conditions include: the reverse current value of each branch current information is greater than a first current threshold, and the voltage value of each branch voltage information is less than a branch voltage threshold; or, the DC-side electrical parameter sampling information includes: the current information of each branch and the DC bus voltage information; the preset protection conditions include: the reverse current value of each branch current information is greater than a first current threshold, and the DC bus voltage information is less than a bus voltage threshold; Alternatively, if the power converter is a string photovoltaic inverter system, the DC-side electrical parameter sampling information includes at least two of the following: branch current information, branch voltage information, and DC bus voltage information; the preset protection conditions include at least two of the following conditions: the reverse current value of each branch current information is greater than a first current threshold, the voltage value of each branch voltage information is less than a branch voltage threshold, and the DC bus voltage information is greater than a bus voltage threshold. Alternatively, if the power converter is a distributed photovoltaic inverter system, the DC-side electrical parameter sampling information includes at least two of the following: the current information of each branch, the voltage information of each power supply on the DC side, and the DC bus voltage information; the preset protection conditions include at least two of the following conditions: the reverse current value of each branch current information is greater than a first current threshold, the voltage value of each power supply voltage information is less than a power supply voltage threshold, and the DC bus voltage information is greater than a bus voltage threshold.

5. The protection system for the power converter according to claim 3 or 4, wherein, The number of the first logic gates is 1, and the hardware protection circuit includes: a first comparison circuit; One input terminal of the first comparison circuit receives the maximum value of the reverse current value of each branch current information. The other input of the first comparator circuit receives the first current threshold. The output terminal of the first comparison circuit serves as the output terminal of the hardware protection circuit.

6. The protection system for the power converter according to claim 3, wherein, The number of the first logic gate is 1, and the hardware protection circuit includes: a second comparison circuit, a third comparison circuit, and a second logic gate; One input terminal of the second comparison circuit receives one of the following: the maximum value of the reverse current of each branch current information, the minimum value of the voltage of each branch voltage information, and the DC bus voltage information. The other input of the second comparator circuit receives the corresponding threshold. The output of the second comparator circuit is connected to one input of the second logic gate; One input terminal of the third comparison circuit receives the maximum value of the reverse current of each branch current information, the minimum value of the voltage of each branch voltage information, and another of the DC bus voltage information. The other input of the third comparison circuit receives the corresponding threshold. The output of the third comparator circuit is connected to another input of the second logic gate. The output of the second logic gate serves as the output of the hardware protection circuit.

7. The protection system for the power converter according to claim 4, wherein, The number of the first logic gate is 1, and the hardware protection circuit includes: a second comparison circuit, a third comparison circuit, and a second logic gate; One input terminal of the second comparison circuit receives, when the power converter is a centralized photovoltaic inverter system, the maximum value of the reverse current of each branch current information; when the power converter is a string photovoltaic inverter system, it receives, one of the maximum value of the reverse current of each branch current information, the minimum value of the voltage of each branch voltage information, and the DC bus voltage information; when the power converter is a distributed photovoltaic inverter system, it receives, one of the maximum value of the reverse current of each branch current information, the minimum value of the voltage of each power supply voltage information, and the DC bus voltage information. The other input of the second comparator circuit receives the corresponding threshold. The output of the second comparator circuit is connected to one input of the second logic gate; One input terminal of the third comparison circuit receives either the minimum voltage value of each branch voltage information or the DC bus voltage information when the power converter belongs to a centralized photovoltaic inverter system; or, when the power converter belongs to a string photovoltaic inverter system, it receives either the maximum reverse current value of each branch current information, the minimum voltage value of each branch voltage information, or the DC bus voltage information; or, when the power converter belongs to a distributed photovoltaic inverter system, it receives either the maximum reverse current value of each branch current information, the minimum voltage value of each power supply voltage information, or the DC bus voltage information. The other input of the third comparison circuit receives the corresponding threshold. The output of the third comparator circuit is connected to another input of the second logic gate. The output of the second logic gate serves as the output of the hardware protection circuit.

8. The protection system for the power converter according to claim 6 or 7, wherein, One input of the second comparison circuit receives the maximum value of the reverse current value of each branch current information, and the other input of the second comparison circuit receives the first current threshold. One input of the third comparison circuit receives the DC bus voltage information, and the other input of the third comparison circuit receives the bus voltage threshold.

9. The protection system for the power converter according to claim 3 or 4, wherein, The number of the first logic gates is greater than 1, and the hardware protection circuit includes: a plurality of first comparison circuits; Each of the first comparison circuits receives a reverse current value corresponding to the branch current information at one of its input terminals. The other input terminal of each of the first comparison circuits receives the first current threshold. The output of each of the first comparison circuits serves as the corresponding output of the hardware protection circuit and is connected to one of the inputs of the corresponding first logic gate.

10. The protection system for the power converter according to claim 3, wherein, The number of the first logic gates is greater than 1, and the hardware protection circuit includes: at least one second comparison circuit, at least one third comparison circuit, and a plurality of second logic gates; The number of second comparison circuits is greater than 1, and the number of third comparison circuits is 1; one input terminal of each second comparison circuit receives the reverse current value or the corresponding branch voltage information; one input terminal of the third comparison circuit receives the DC bus voltage information; the two input terminals of the second logic gate are respectively connected to the output terminals of the corresponding second comparison circuit and the third comparison circuit. Alternatively, the number of both the second and third comparison circuits is greater than 1, with one input terminal of each second comparison circuit receiving the reverse current value of the corresponding branch current information; one input terminal of each third comparison circuit receiving the corresponding branch voltage information; and the two input terminals of the second logic gate being connected to the output terminals of the corresponding second and third comparison circuits, respectively. The other input terminal of the second comparison circuit and the other input terminal of the third comparison circuit respectively receive the corresponding threshold. The output of each of the second logic gates serves as the corresponding output of the hardware protection circuit and is connected to one of the inputs of the corresponding first logic gate.

11. The protection system for the power converter according to claim 4, wherein, The number of the first logic gates is greater than 1, and the hardware protection circuit includes: at least one second comparison circuit, at least one third comparison circuit, and a plurality of second logic gates; The number of second comparison circuits is greater than 1, and the number of third comparison circuits is 1. One input terminal of each second comparison circuit receives the reverse current value of the corresponding branch current information when the power converter is a centralized photovoltaic inverter system; receives the reverse current value or the corresponding branch voltage information when the power converter is a string photovoltaic inverter system; and receives the reverse current value or the corresponding power supply voltage information when the power converter is a distributed photovoltaic inverter system. One input terminal of the third comparison circuit receives the DC bus voltage information. The two input terminals of the second logic gate are respectively connected to the output terminals of the corresponding second comparison circuit and the third comparison circuit. Alternatively, the number of both the second and third comparison circuits is greater than 1. One input terminal of each second comparison circuit receives the reverse current value of the corresponding branch current information. One input terminal of each third comparison circuit receives the corresponding branch voltage information when the power converter is a centralized photovoltaic inverter system or a string photovoltaic inverter system, and receives the corresponding power supply voltage information when the power converter is a distributed photovoltaic inverter system. The two input terminals of the second logic gate are respectively connected to the output terminals of the corresponding second and third comparison circuits. The other input terminal of the second comparison circuit and the other input terminal of the third comparison circuit respectively receive the corresponding threshold. The output of each of the second logic gates serves as the corresponding output of the hardware protection circuit and is connected to one of the inputs of the corresponding first logic gate.

12. The protection system for the power converter according to claim 5 or 9, wherein, The hardware protection circuit also includes: at least one third logic gate; One input terminal of the third logic gate is connected to the output terminal of the corresponding first comparison circuit; The other input of the third logic gate receives a characterization signal sent by the control module; when the AC side switch of the power converter is open, the characterization signal causes the hardware protection circuit to not output a protection signal. The output of the third logic gate serves as one output of the hardware protection circuit.

13. The protection system for the power converter according to any one of claims 6, 7, 10, and 11, wherein, The second logic gate also has another input terminal, which receives the characterization signal sent by the control module; when the AC side switch of the power converter is open, the characterization signal causes the hardware protection circuit to not output a protection signal.

14. The protection system for the power converter according to claim 3 or 4, wherein, The control module is configured to perform threshold comparisons on different types of information in the DC-side electrical parameter sampling information, and generate and output the protection signal when the comparison results at each level exceed the corresponding threshold.

15. The protection system for the power converter according to any one of claims 1 to 14, wherein, The protection system further includes: a fourth comparison circuit and at least one fourth logic gate; One input terminal of the fourth comparator circuit receives power supply voltage sampling information from the protection system. The other input terminal of the fourth comparator circuit receives the power supply voltage threshold. The two input terminals of the fourth logic gate are respectively connected to the output terminal of the fourth comparator circuit and the output terminal of the corresponding first logic gate; The output of the fourth logic gate is connected to the control terminal of the corresponding excitation fuse on the DC side of the power converter. When the power supply voltage sampling information of the protection system is lower than the power supply voltage threshold, the output signal of the fourth comparison circuit causes the fourth logic gate not to output a trigger signal.

16. A protection method for a power converter, wherein, A control module applied in a protection system for a power converter as described in any one of claims 1 to 15; the protection method includes: Determine whether any of the reverse current values ​​in the DC-side branch current information of the power converter are greater than the second current threshold. If the reverse current value is greater than the second current threshold, then determine whether the DC side branch voltage information or DC bus voltage information of the power converter meets the preset voltage conditions. If the branch voltage information or the DC bus voltage information meets the preset voltage condition, it is determined that an external short-circuit fault has occurred on the DC side of the power converter, and a protection signal is generated and output.

17. The protection method for a power converter according to claim 16, wherein, Determining whether the DC bus voltage information meets the preset voltage condition includes: Determine whether the average value of the DC bus voltage information within a preset time period is less than the bus voltage threshold; If the average value is less than the bus voltage threshold, then the DC bus voltage information is determined to meet the preset voltage condition.

18. The protection method for a power converter according to claim 16 or 17, wherein, Determining whether the voltage information of each branch meets the preset voltage condition includes: Determine whether the voltage information of each branch is less than the branch voltage threshold; If the branch voltage information is less than the branch voltage threshold, then it is determined that the branch voltage information satisfies the preset voltage condition.

19. The protection method for a power converter according to claim 16, wherein, Determining whether the DC bus voltage information meets the preset voltage condition includes: When the power converter is a centralized photovoltaic inverter system, it is determined whether the DC bus voltage information is less than the bus voltage threshold; if the DC bus voltage information is less than the bus voltage threshold, it is determined that the DC bus voltage information meets the preset voltage condition. When the power converter belongs to a distributed photovoltaic inverter system or a string photovoltaic inverter system, it is determined whether the DC bus voltage information is greater than the bus voltage threshold; if the DC bus voltage information is greater than the bus voltage threshold, it is determined that the DC bus voltage information meets the preset voltage condition.

20. The protection method for a power converter according to claim 16 or 19, wherein, When the power converter is a distributed photovoltaic inverter system, the corresponding power supply voltage information is used instead of the branch voltage information to determine whether the preset voltage condition is met. Determining whether the voltage information of each power supply line meets the preset voltage condition includes: Determine whether the power supply voltage information of each path is less than the power supply voltage threshold; If the power supply voltage information is less than the power supply voltage threshold, then it is determined that the power supply voltage information satisfies the preset voltage condition.

21. The protection method for a power converter according to any one of claims 16 to 20, wherein, After determining that the branch voltage information exists or the DC bus voltage information meets the preset voltage condition, the protection method further includes: Determine whether the sum of the positive current values ​​of the other branch current information is greater than the third current threshold. If the sum of the positive current values ​​is greater than the third current threshold, then the step of determining that an external short-circuit fault has occurred on the DC side of the power converter is executed.

22. A power converter, wherein, include: The main circuit, multiple excitation fuses, a detection module, a controller, and a protection system for the power converter as described in any one of claims 1 to 15; The DC side of the main circuit is connected to the corresponding DC side interface of the power converter through at least one transmission branch; the DC side interface of the power converter is used to connect to the photovoltaic power source. At least one of the positive and negative branches of the transmission branch is provided with a corresponding excitation fuse; The detection module is configured to sample DC-side electrical parameters of the power converter. The main circuit is controlled by the controller; The excitation fuse is controlled by the protection system.

23. The power converter according to claim 22, wherein, The control module in the protection system is integrated into the controller, or the control module is independent of the controller.

24. The power converter according to claim 22 or 23, wherein, The main circuit includes a DC / AC conversion circuit; the DC side of the DC / AC conversion circuit serves as the DC side of the main circuit, and the AC side of the DC / AC conversion circuit serves as the AC side of the main circuit.

25. The power converter according to claim 24, wherein, The main circuit also includes: at least one DC / DC converter circuit; The DC side of the DC / AC conversion circuit is connected to the corresponding transmission branch through the DC / DC conversion circuit.

26. A control device, wherein, The device includes a processor and a memory configured to store programs, instructions, or code, and the processor configured to execute the programs, instructions, or code in the memory to perform the protection method for the power converter as described in any one of claims 16 to 21.

27. A computer-readable storage medium, wherein, The device contains a computer program that is loaded by a processor to execute the protection method for the power converter as described in any one of claims 16 to 21.

Images