Method for snow melting of a photovoltaic system and photovoltaic system

Abstract

The application relates to a snow melting method of a photovoltaic system and the photovoltaic system. The method comprises the following steps: generating a first snow melting control instruction; the first snow melting control instruction is used for instructing a bidirectional direct-current alternating-current converter to heat and melt snow of x photovoltaic components to be melted snow by using alternating current of a power grid; in response to the fact that the photovoltaic components to be melted snow have been melted snow, at least one subsequent snow melting control instruction is generated; the subsequent snow melting control instruction is used for instructing a bidirectional direct-current alternating-current converter to heat and melt snow of y photovoltaic components to be melted snow by using at least part of current generated by at least one photovoltaic component that has been melted snow until the number of the photovoltaic components that have been melted snow reaches a target number. Through the method, energy consumption other than energy generated by the photovoltaic components can be reduced.

Description

Technical Field

[0001] This application relates to the field of new energy technology, and in particular to a snow melting method and a photovoltaic system. Background Technology

[0002] Photovoltaic modules are the core component of a photovoltaic power generation system. The power generation of a photovoltaic module is closely related to the amount of sunlight it receives. When the surface of a photovoltaic module is covered with snow, its power generation will decrease significantly.

[0003] In related technologies, photovoltaic modules are typically heated and snow melted using electricity provided by the power grid or energy storage devices, which consumes a large amount of electricity from the power grid or energy storage devices. Summary of the Invention

[0004] Therefore, it is necessary to provide a snow melting method and photovoltaic system for a photovoltaic system that can reduce the consumption of energy other than the electricity provided by the photovoltaic system, in order to address the above-mentioned technical problems.

[0005] In a first aspect, this application provides a snow melting method for a photovoltaic system, applied to a photovoltaic system connected to the power grid and comprising multiple photovoltaic modules and multiple bidirectional DC-AC converters, wherein one bidirectional DC-AC converter corresponds to at least one of the photovoltaic modules, and the method includes:

[0006] Generate the first snow melting control command; the first snow melting control command is used to instruct a bidirectional DC-AC converters to use the AC current of the grid to heat and melt the snow on x photovoltaic modules to be melted;

[0007] In response to the fact that the photovoltaic modules to be melted have been melted, at least one subsequent snow melting control command is generated; the subsequent snow melting control command is used to instruct b bidirectional DC-AC converters to use at least a portion of the current generated by at least one melted photovoltaic module to heat and melt the snow on y photovoltaic modules to be melted until the number of melted photovoltaic modules reaches the target number.

[0008] The subsequent snow melting control command is a command used to control the remaining bidirectional DC-AC converters other than the bidirectional DC-AC converter corresponding to the first snow melting control command, after the first snow melting control command instructs at least one bidirectional DC-AC converter to operate and at least one photovoltaic module with melted snow is obtained.

[0009] In one embodiment, the first snow melting control command is an instruction in the photovoltaic system to control at least one bidirectional DC-AC converter. The first snow melting control command includes a first sub-instructions, each of which corresponds to a bidirectional DC-AC converter.

[0010] Each subsequent snow melting control command includes b second sub-commands, and each second sub-command corresponds to a bidirectional DC-AC converter.

[0011] In one embodiment, x is less than or equal to a first quantity threshold, which is less than or equal to the number of all photovoltaic modules in the photovoltaic system that need to be melted.

[0012] In one embodiment, the subsequent snow melting control command carries a current threshold.

[0013] In response to the fact that the photovoltaic modules awaiting snow melting have already melted, at least one subsequent snow melting control command is generated; the subsequent snow melting control command is used to instruct b bidirectional DC-AC converters to use at least a portion of the current generated by at least one photovoltaic module that has already melted to heat and melt the snow on y photovoltaic modules awaiting snow melting, including:

[0014] The quantity of y is determined based on the ratio of the current value generated by the photovoltaic modules that have already melted snow to the current threshold.

[0015] If the current generated by the photovoltaic modules that have already melted snow is greater than the current threshold, the first part of the current generated by the photovoltaic modules that have already melted snow is used to heat y photovoltaic modules that need to be melted snow; the second part of the current generated by the photovoltaic modules that have already melted snow is transmitted to the power grid.

[0016] In one embodiment, at least some of the subsequent snow melting control commands indicate a number of photovoltaic modules to be heated for snow melting that is greater than the number of photovoltaic modules to be heated for snow melting indicated by the previous subsequent snow melting control command.

[0017] In one embodiment, the subsequent snow melting control command carries a current threshold.

[0018] If the current value generated by the already melted photovoltaic modules is less than or equal to the current threshold, the subsequent snow melting control command is used to instruct the third part of the current generated by the already melted photovoltaic modules to heat and melt the snow on y photovoltaic modules to be melted.

[0019] In one embodiment, the subsequent snow melting control command carries an identifier for the component to be melted, which indicates any of the following:

[0020] The photovoltaic modules awaiting snow melting are identified as the y-th photovoltaic modules closest to those that have already had their snow melted;

[0021] The photovoltaic modules awaiting snow melting are identified as the yth photovoltaic modules with the highest historical power generation.

[0022] Subsequent snow melting control commands are used to instruct the use of the current generated by at least one already melted photovoltaic module to heat and melt the snow on the photovoltaic modules corresponding to the y modules to be melted.

[0023] Secondly, this application also provides a snow melting method for a photovoltaic system, wherein the photovoltaic system is connected to the power grid and includes multiple photovoltaic modules and multiple bidirectional DC-AC converters, each bidirectional DC-AC converter corresponding to at least one photovoltaic module, and the method is applied to any one of the bidirectional DC-AC converters, the method comprising:

[0024] Obtain a first sub-instruction from the first snow melting control command; in response to the first sub-instruction, use the alternating current from the power grid to heat and melt the snow on at least one photovoltaic module to be melted; the first snow melting control command includes a first sub-instructions, each first sub-instruction corresponding to a bidirectional DC-AC converter; or,

[0025] Obtain a second sub-instruction from a subsequent snow melting control instruction, and in response to the second sub-instruction, use the current generated by at least one photovoltaic module that has already melted snow to heat and melt the snow on at least one photovoltaic module to be melted; each subsequent snow melting control instruction includes b second sub-instructions, and each second sub-instruction corresponds to a bidirectional DC-AC converter;

[0026] The subsequent snow melting control command is a command used to control the remaining bidirectional DC-AC converters other than the bidirectional DC-AC converter corresponding to the first snow melting control command, after the first snow melting control command instructs at least one bidirectional DC-AC converter to operate and at least one photovoltaic module with melted snow is obtained.

[0027] In one embodiment, when a subsequent snow melting control command is included, the subsequent snow melting control command carries a current threshold.

[0028] If the current generated by the already melted photovoltaic modules exceeds a current threshold, the first portion of the current generated by the already melted photovoltaic modules is used to heat and melt the snow in at least one photovoltaic module to be melted; or,

[0029] If the current value generated by the photovoltaic modules that have already melted snow is less than or equal to the current threshold, the third part of the current generated by the photovoltaic modules that have already melted snow is used to heat and melt the snow on at least the photovoltaic modules that need to be melted.

[0030] In one embodiment, after heating and melting the photovoltaic modules to be melted in response to a first sub-instruction or a second sub-instruction, the method further includes:

[0031] Obtain a power generation control command; in response to the power generation control command, transmit a second portion of the current generated by the snow-melted photovoltaic modules to the photovoltaic modules to be melted and / or the power grid.

[0032] Thirdly, this application also provides a photovoltaic system, which is connected to the power grid and includes multiple photovoltaic modules and multiple bidirectional DC-AC converters, wherein one bidirectional DC-AC converter corresponds to at least one photovoltaic module;

[0033] A bidirectional DC-AC converter receives a first sub-instruction from a first snow melting control command. In response to the first sub-instruction, it uses the AC current from the power grid to heat and melt the snow from at least one photovoltaic module to be melted. The first snow melting control command includes *a* first sub-instructions, each corresponding to one bidirectional DC-AC converter, or...

[0034] The bidirectional DC-AC converter acquires a second sub-instruction from a subsequent snow melting control command. In response to the second sub-instruction, it uses the current generated by at least one already melted photovoltaic module to heat and melt the snow on at least one photovoltaic module to be melted. Each subsequent snow melting control command includes b second sub-instructions, and each second sub-instruction corresponds to a bidirectional DC-AC converter.

[0035] The subsequent snow melting control command is a command used to control the remaining bidirectional DC-AC converters other than the bidirectional DC-AC converter corresponding to the first snow melting control command, after the first snow melting control command instructs at least one bidirectional DC-AC converter to operate and at least one photovoltaic module with melted snow is obtained.

[0036] In one embodiment, the circuit topology of the bidirectional DC-AC converter is a resonant dual active bridge circuit topology.

[0037] In one embodiment, the bidirectional DC-AC converter includes a DC-side conversion circuit, a transformer, and an AC-side conversion circuit. The DC-side conversion circuit includes a first full-bridge conversion circuit, and the AC-side conversion circuit includes a bidirectional switched half-bridge conversion circuit.

[0038] In one embodiment, the bidirectional DC-AC converter includes a DC-side conversion circuit, a transformer, and an AC-side conversion circuit. The DC-side conversion circuit includes a first full-bridge conversion circuit, and the AC-side conversion circuit includes a second full-bridge conversion circuit and a power frequency switching circuit. The first terminal of the second full-bridge conversion circuit is connected to the transformer, and the second terminal of the second full-bridge conversion circuit is connected to the first terminal of the power frequency switching circuit. The second terminal of the power frequency switching circuit is connected to the power grid.

[0039] The aforementioned snow-melting method and photovoltaic system convert alternating current from the power grid into direct current to heat and melt snow from at least one photovoltaic module. This limits the amount of grid-side energy used for initial snow melting, effectively controlling energy consumption by non-photovoltaic systems. After obtaining the melted photovoltaic modules, the current generated by these modules is used to heat and melt the remaining snow from the photovoltaic modules to be melted. This process is repeated until the target number is reached. This allows the energy generated by the photovoltaic system to heat and melt snow from the photovoltaic modules within the system, further reducing energy consumption by non-photovoltaic systems. In other words, it enables the use of relatively small grid energy as initial energy to drive the photovoltaic system to heat and melt snow based on its own generated energy, reducing energy consumption other than that generated by the photovoltaic system. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of an exemplary architecture of a photovoltaic system to which a snow melting method is applied in one embodiment.

[0042] Figure 2 This is a schematic diagram of an exemplary architecture of a photovoltaic system to which a snow melting method is applied in another embodiment of the photovoltaic system.

[0043] Figure 3 This is a schematic diagram showing the connection between the bidirectional DC-AC converter and the photovoltaic module of the photovoltaic system used in the snow melting method of the photovoltaic system in one embodiment.

[0044] Figure 4 This is one of the schematic flowcharts of a snow melting method for a photovoltaic system in one embodiment.

[0045] Figure 5 This is one of the snow melting diagrams of a photovoltaic system in one embodiment.

[0046] Figure 6 This is the second schematic diagram of a snow melting method for a photovoltaic system in one embodiment.

[0047] Figure 7 This is the third schematic diagram of a snow melting method for a photovoltaic system in one embodiment.

[0048] Figure 8This is a schematic diagram illustrating the snow melting method of a photovoltaic system in one embodiment.

[0049] Figure 9 This is the second schematic flowchart of a snow melting method for a photovoltaic system in one embodiment.

[0050] Figure 10 This is the third flowchart illustrating a snow melting method for a photovoltaic system in one embodiment.

[0051] Figure 11 This is a schematic diagram of the structure of a bidirectional DC-AC converter in one embodiment.

[0052] Figure 12 This is a schematic diagram of the circuit topology of a bidirectional DC-AC converter in one embodiment.

[0053] Figure 13 This is a schematic diagram of the circuit topology of a bidirectional DC-AC converter in another embodiment.

[0054] Figure 14 This is a schematic diagram of the circuit topology of a bidirectional DC-AC converter in another embodiment. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0056] It should be noted that the terms "first," "second," etc., used in this application can be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from the second element. The terms "comprising" and "having," and any variations thereof, used in this application, are intended to cover non-exclusive inclusion. The term "multiple" used in this application refers to two or more. The term "and / or" used in this application refers to one of the embodiments, or any combination of multiple embodiments.

[0057] Please refer to Figure 1 and Figure 2 This is a schematic diagram of an exemplary architecture of a photovoltaic system in which the snow melting method provided in this application is applied. Figure 1As shown, the photovoltaic system includes multiple bidirectional DC-AC converters 100 and multiple photovoltaic modules 200. The DC terminal of each bidirectional DC-AC converter 100 is connected to at least one photovoltaic module 200, and the AC terminal is connected to the power grid 300. When the photovoltaic module 200 generates electricity, the bidirectional DC-AC converter 100 converts the DC power generated by the photovoltaic module 200 into AC power and supplies it to the power grid 300. In the snow melting scenario of some embodiments of this application, the bidirectional DC-AC converter 100 converts the energy from the power grid 300 into DC power and supplies it to the photovoltaic module 200 to generate a heating current and melt the snow on the surface of the photovoltaic module. In the snow melting scenario of other embodiments of this application, one bidirectional DC-AC converter 100 outputs the energy from the photovoltaic module 200 that has already had its snow melted, and another bidirectional DC-AC converter 100 supplies the energy from the photovoltaic module that has already had its snow melted to the photovoltaic module 200 that needs snow melting, so that the photovoltaic module 200 can generate a heating current and melt the snow on its surface. In some embodiments, the bidirectional DC-AC converter 100 adopts a dual active bridge (DAB) circuit topology.

[0058] In one possible implementation, the DC terminal of a bidirectional DC-AC converter 100 is as follows: Figure 1 The diagram shows a set of connection ports, such as a set of connection ports connected to a photovoltaic module 200.

[0059] In one possible implementation, the DC terminal of the bidirectional DC-AC converter 100 includes multiple sets of connection ports, such as... Figure 2 As shown, a set of connection ports is connected to one photovoltaic module 200. Thus, a bidirectional DC-AC converter 100 can connect to multiple photovoltaic modules 200 through multiple sets of connection ports. It is understood that, as... Figure 2 As shown, when the bidirectional DC-AC converter 100 has multiple sets of connection ports, some connection ports may not be connected to the photovoltaic module 200.

[0060] The output terminals of multiple photovoltaic modules corresponding to one bidirectional DC-AC converter are connected in parallel. The following example illustrates this: one bidirectional DC-AC converter corresponds to two photovoltaic modules. Figure 3 As shown, the output terminals of two photovoltaic modules 200 are connected in parallel. This parallel connection can be achieved through the internal circuit structure of the bidirectional DC-AC converter 100 or through external connecting lines to the bidirectional DC-AC converter 100. Since the output terminals of multiple photovoltaic modules 200 are connected in parallel to the input terminal of the bidirectional DC-AC converter 100, increasing the number of photovoltaic modules 200 will not have a significant impact on the voltage at the input terminal of the bidirectional DC-AC converter 100, making the control of voltage and current by the bidirectional DC-AC converter 100 simpler.

[0061] In one embodiment, a snow melting method for a photovoltaic system is provided, the method being applied to... Figure 1 or Figure 2 The photovoltaic system shown includes multiple photovoltaic modules and multiple bidirectional DC-AC converters. Each bidirectional DC-AC converter corresponds to at least one photovoltaic module, indicating that the DC terminal of the bidirectional DC-AC converter is connected to at least one photovoltaic module. In addition, the AC terminal of the bidirectional DC-AC converter is used to connect to the power grid.

[0062] In the snow melting method of the photovoltaic system in this embodiment, the first snow melting control command and subsequent snow melting control commands can be generated by a control terminal, which is communicatively connected to each bidirectional DC-AC converter. The control terminal can be integrated into the photovoltaic system or located outside the photovoltaic system; this embodiment does not impose any limitations.

[0063] As a logical functional module, the control terminal can be physically distributed within the photovoltaic system, user terminal equipment, or a cloud platform, or a combination of user mobile devices and the cloud platform. For example, the cloud platform or user terminal equipment may be configured with corresponding applications (APPs). User terminal equipment can be, but is not limited to, various personal computers, laptops, smartphones, tablets, control consoles installed in the monitoring room, drones, low-altitude aircraft, IoT devices, and portable wearable devices. IoT devices can include smart speakers, smart TVs, smart air conditioners, smart vehicle equipment, and projection equipment. Portable wearable devices can include smartwatches, smart bracelets, and head-mounted displays. Head-mounted displays can be virtual reality (VR) devices, augmented reality (AR) devices, and smart glasses.

[0064] For example, the control terminal communicates with each bidirectional DC-AC converter via a wireless communication link; the wireless communication link includes, but is not limited to, Sub-1G communication link, Zigbee communication link, WIFI communication link, and Bluetooth communication link.

[0065] In another example, the photovoltaic system also includes a gateway controller. A control terminal communicates with each bidirectional DC-AC converter via the gateway controller. The bidirectional DC-AC converters communicate with the gateway controller via a wired or wireless communication link. For example, the wired communication link between the bidirectional DC-AC converters and the gateway controller includes, but is not limited to, a power line carrier communication link or an RS-485 (Recommended Standard 485) communication link. The control terminal communicates with the gateway controller via a wired or wireless communication link. For example, the wired communication link between the control terminal and the gateway controller includes, but is not limited to, an Ethernet communication link or a fiber optic communication link.

[0066] See Figure 4 This application provides a snow melting method for a photovoltaic system, including steps S102 to S104.

[0067] In step S102, the photovoltaic system generates a first snow melting control command; the first snow melting control command is used to instruct a bidirectional DC-AC converters to use the AC current of the grid to heat and melt the snow on x photovoltaic modules to be melted.

[0068] Where a is less than or equal to x.

[0069] When one bidirectional DC-AC converter corresponds to one photovoltaic module, a equals x. When one bidirectional DC-AC converter corresponds to multiple photovoltaic modules, a is less than x. By limiting the number of photovoltaic modules that use grid AC current for snow melting, it is not necessary to use grid AC current to melt snow on all photovoltaic modules, which can effectively reduce the use of grid-side energy and thus reduce the consumption of energy outside the photovoltaic system.

[0070] The first snow melting control command is a command in a photovoltaic system to control at least one bidirectional DC-AC converter. That is, the first snow melting control command can instruct one or multiple bidirectional DC-AC converters to operate. When the first snow melting control command is used to control one bidirectional DC-AC converter, it is sent directly to that converter. When the first snow melting control command is used to control multiple bidirectional DC-AC converters, it can be sent to all of them simultaneously or sequentially.

[0071] For example, the photovoltaic system includes six bidirectional DC-AC converters. Each bidirectional DC-AC converter is connected to two photovoltaic modules that are to be melted. Two of the bidirectional DC-AC converters are selected to receive a first snow-melting control command. Responding to the first snow-melting control command, the two bidirectional DC-AC converters convert the AC current from the power grid into DC current, which is then fed back to the connected photovoltaic modules to be melted, thus achieving snow melting through heating. In this example, a is 2 and x is 4.

[0072] In another example, see Figure 5 The photovoltaic system includes 1 to N bidirectional DC-AC converters. Each bidirectional DC-AC converter is connected to a photovoltaic module that needs to be melted (for snow removal). The first bidirectional DC-AC converter receives a first snow removal control command and, in response, converts the AC current from the power grid into DC current, which is then fed back to the connected photovoltaic module to be melted, thus heating and melting the snow. In this example, a is 1 and x is 1.

[0073] In step S104, the photovoltaic system generates at least one subsequent snow melting control command in response to the fact that the photovoltaic modules to be melted have been melted. The subsequent snow melting control command is used to instruct b bidirectional DC-AC converters to use at least a portion of the current generated by at least one melted photovoltaic module to heat and melt the y photovoltaic modules to be melted until the number of melted photovoltaic modules reaches the target number.

[0074] Where b is less than or equal to y.

[0075] When one bidirectional DC-AC converter corresponds to one photovoltaic module, b equals y. When one bidirectional DC-AC converter corresponds to multiple photovoltaic modules, b is less than y. By limiting the number of photovoltaic modules that generate current to heat and melt snow, the use of grid-side energy can be further reduced, thereby reducing energy consumption outside the photovoltaic system. Subsequent snow-melting control commands are commands used to control the remaining bidirectional DC-AC converters other than the one corresponding to the first snow-melting control command, after the first snow-melting control command instructs at least one bidirectional DC-AC converter to operate and at least one photovoltaic module has been melted.

[0076] A single subsequent snow melting control command can be used to instruct one or more bidirectional DC-AC converters to operate. When a single subsequent snow melting control command controls one bidirectional DC-AC converter, the command is sent directly to that converter. When a single subsequent snow melting control command controls multiple bidirectional DC-AC converters, the command can be sent to all converters simultaneously or sequentially.

[0077] After the bidirectional DC-AC converter, in response to the first subsequent snow melting control command, converts y photovoltaic modules awaiting snow melting into already melted photovoltaic modules, the photovoltaic system can continue to generate subsequent snow melting control commands, which are then applied to the bidirectional DC-AC converters connected to other photovoltaic modules awaiting snow melting. That is, subsequent snow melting control commands can be generated as soon as the photovoltaic modules awaiting snow melting are converted into already melted photovoltaic modules. This conversion can be based on either the first snow melting control command heating the photovoltaic modules, or a previous subsequent snow melting control command heating the photovoltaic modules.

[0078] Continue referring to the aforementioned example, see Figure 6 The photovoltaic system includes N bidirectional DC-AC converters (taking N greater than 4 as an example; for ease of illustration, the serial numbers of the N bidirectional DC-AC converters are respectively: 1, 2, 3, ..., N, and the photovoltaic modules corresponding to each bidirectional DC-AC converter are respectively denoted as: 1, 2, 3, ..., N). Among them, bidirectional DC-AC converter 1 receives the first snow melting control command and heats and melts the snow on the photovoltaic module 1 connected to bidirectional DC-AC converter 1 based on the first snow melting control command. After converting the photovoltaic module 1 connected to bidirectional DC-AC converter 1 into a snow-melted photovoltaic module, bidirectional DC-AC converters 2, 3, and 4 (taking three bidirectional DC-AC converters receiving subsequent snow melting control commands as an example) can be used to receive subsequent snow melting control commands and heat and melt the snow on the photovoltaic modules 2, 3, and 4 connected to bidirectional DC-AC converters 2, 3, and 4 based on the subsequent snow melting control commands. If N can be 8, after the bidirectional DC-AC converters 2, 3, and 4 receive the first subsequent snow melting control command, heat and melt the connected photovoltaic modules 2, 3, and 4 to be melted, and convert them into photovoltaic modules with melted snow, the bidirectional DC-AC converters 5, 6, 7, and 8 can be used to receive the second subsequent snow melting control command, and use the current generated by the photovoltaic modules 1, 2, 3, and 4 with melted snow to heat and melt the photovoltaic modules 5, 6, 7, and 8 connected to the bidirectional DC-AC converters 5, 6, 7, and 8.

[0079] Each bidirectional DC-AC converter receives only one subsequent snow melting control command per cycle. A cycle refers to a period that may involve one snow cover and one snow melting, such as 8 hours, 12 hours, 24 hours, etc., without limitation.

[0080] See Figure 7 The photovoltaic system includes N photovoltaic modules to be melted, with a target quantity of N. After the snow is melted by heating all N photovoltaic modules, the N photovoltaic modules generate electricity to supply power to the grid.

[0081] The aforementioned snow-melting method for photovoltaic (PV) systems converts alternating current from the power grid into direct current to heat and melt snow from at least one PV module. This limits the amount of grid-side energy used for initial snow melting, effectively controlling energy consumption by non-PV systems. After obtaining the PV modules with melted snow, the current generated by these modules is used to heat and melt the remaining snow. This process is repeated until the target number is reached. This allows the energy generated by the PV system to heat and melt snow from the PV modules within the system, further reducing energy consumption by non-PV systems. In other words, it enables the use of relatively small grid energy as initial energy to drive the PV system to heat and melt snow based on its own generated energy, reducing energy consumption beyond what is generated by the PV system itself.

[0082] In one embodiment, the first snow melting control command is an instruction in the photovoltaic system to control at least one bidirectional DC-AC converter. The first snow melting control command includes *a* first sub-instructions, each corresponding to one bidirectional DC-AC converter. That is, *a* is greater than or equal to 1.

[0083] Each subsequent snow melting control command includes b second sub-commands, and each second sub-command corresponds to a bidirectional DC-AC converter. That is, b is greater than or equal to 1.

[0084] The number of second sub-instructions included in each subsequent snow melting control instruction may be the same or different; that is, the number of 'b' in each subsequent snow melting control instruction may be the same or different, and no restriction is imposed here.

[0085] For example, if a=1, the first snow melting control command includes one first sub-command, which controls one bidirectional command AC converter. If a=2, the first snow melting control command includes two first sub-commands, each controlling a corresponding bidirectional command AC converter. For instance, the first first sub-command controls the first bidirectional DC-AC converter, and the second first sub-command controls the second bidirectional DC-AC converter. The number of 'a's is determined by the number of bidirectional DC-AC converters to be controlled or the number of photovoltaic modules that need to melt snow based on the AC current from the grid side, and is not limited here.

[0086] If b=1, the subsequent snow melting control command includes one second sub-command, which controls one bidirectional command AC converter. If a=2, the subsequent snow melting control command includes two second sub-commands, each controlling a corresponding bidirectional command AC converter. For example, the first second sub-command controls the first bidirectional DC-AC converter, and the second second sub-command controls the second bidirectional DC-AC converter. The number of b is determined by the number of bidirectional DC-AC converters to be controlled or the number of photovoltaic modules that need snow melting in the next round (the next time subsequent snow melting control commands are received), and is not limited here.

[0087] When the first sub-instruction / second sub-instruction includes multiple sub-instructions, the multiple instructions can be sent to the corresponding bidirectional DC-AC converters simultaneously, or they can be sent to the corresponding bidirectional DC-AC converters one by one.

[0088] By limiting one instruction to one bidirectional DC-AC converter, the response rate of the bidirectional DC-AC converter can be improved, and its reliability can be increased.

[0089] In one embodiment, x is less than or equal to a first quantity threshold, which is less than or equal to the total number of photovoltaic modules in the photovoltaic system awaiting snow melting. The first quantity threshold can be set as needed within a range that is less than or equal to the total number of photovoltaic modules in the photovoltaic system awaiting snow melting.

[0090] For example, to minimize energy consumption on the grid side, a first quantity threshold is set to 1, allowing the alternating current from the grid side to heat and melt the snow on a single photovoltaic module awaiting snow melting. In another example, to improve the snow melting efficiency of photovoltaic modules while reducing grid-side energy consumption, the number of photovoltaic modules awaiting snow melting using grid-side energy can be increased to increase the current output of the initially melted photovoltaic modules. In this case, the first quantity threshold can be less than or equal to one-third of the total number of photovoltaic modules awaiting snow melting in the photovoltaic system. The first quantity threshold can also be set to one-half, two-thirds, etc., of the total number of photovoltaic modules awaiting snow melting in the photovoltaic system; no limitation is imposed here.

[0091] By limiting the first quantity threshold, the number of photovoltaic modules that use grid-side energy for heating and snow melting can be further limited, thereby controlling the energy obtained from the grid side.

[0092] In one embodiment, the subsequent snow melting control command carries a current threshold.

[0093] In response to the fact that the photovoltaic modules awaiting snow melting have already melted, at least one subsequent snow melting control command is generated; the subsequent snow melting control command is used to instruct b bidirectional DC-AC converters to use at least a portion of the current generated by at least one photovoltaic module that has already melted to heat and melt the snow on y photovoltaic modules awaiting snow melting, including:

[0094] The quantity of y is determined based on the ratio of the current value generated by the photovoltaic modules after snow melting to the current threshold.

[0095] If the current generated by the photovoltaic module that has already melted snow is greater than the current threshold, the subsequent snow melting control command uses the first part of the current generated by the photovoltaic module that has already melted snow to heat the photovoltaic module to be melted; and transmits the second part of the current generated by the photovoltaic module that has already melted snow to the power grid.

[0096] The current threshold carried in the subsequent snow melting control command is the target current value used to heat the photovoltaic modules to melt the snow. It can be set based on experience, or the current threshold can be derived from the heating power required for the photovoltaic modules to melt the snow. There are no restrictions on this. The current value of the grid for heating the photovoltaic modules to melt the snow can also be set with reference to the current threshold.

[0097] If the current generated by the already melted snow photovoltaic modules exceeds a current threshold, it indicates that the current generated by the melted snow photovoltaic modules is sufficient to charge the photovoltaic modules still needing snow melting. Therefore, the second portion of the current can be transmitted to the grid for power supply. Furthermore, a portion of the current can also be transmitted to an energy storage system. Based on the ratio of the generated current value to the current threshold, the maximum number of photovoltaic modules that the generated current value can heat for snow melting can be obtained. Then, based on the maximum number of photovoltaic modules that can be heated for snow melting, the quantity y is determined. For example, y is equal to the integer part of the ratio of the generated current value to the current threshold. In another example, y is less than the integer part of the ratio of the generated current value to the current threshold. The first portion of the current can be the product of the number of photovoltaic modules needing snow melting and the current threshold, and the second portion of the current can be the difference between the generated current value and the first portion of the current value, or it can be less than that difference.

[0098] For example, see Figure 8 The photovoltaic system includes N bidirectional DC-AC converters, where N is 11. Each bidirectional DC-AC converter is connected to one photovoltaic module. There are 10 photovoltaic modules that have already had their snow melted. The current generated by these 10 modules is 100A, and the current threshold is 80A. The generated current of 100A is compared with the current threshold of 80A, and the ratio is 1.25. The quantity of y is determined to be 1. The first portion of the current generated by the melted photovoltaic modules can be used to heat and melt the snow on a photovoltaic module that needs to be melted. The second portion of the current can be transmitted to the grid or an energy storage system. In this example, the first portion of the current can be 80A, and the second portion can be 20A.

[0099] In another example, the photovoltaic system has N bidirectional DC-AC converters, each connected to two photovoltaic modules. There are 15 photovoltaic modules that have already had their snow melted, and the current generated by these 15 modules is 300A. The current threshold is 80A. Comparing 300A with 80A, the integer part is 3. If the subsequent snow melting control command includes two second sub-commands, which are sent to two bidirectional DC-AC converters respectively to heat and melt the snow on four photovoltaic modules, it will reduce the snow melting efficiency of a single photovoltaic module. In this case, y can be 2, and a second sub-command is sent to one bidirectional DC-AC converter to heat and melt the snow on the two photovoltaic modules connected to that converter, so as to use the current value corresponding to the current threshold as much as possible to heat and melt the snow on the photovoltaic modules.

[0100] By limiting the current generated by the already melted photovoltaic modules to a value greater than a current threshold, the first part of the current generated by the already melted photovoltaic modules is used to heat the photovoltaic modules to be melted, thereby reducing the power loss of the grid or other energy storage devices. Furthermore, the second part of the current generated by the already melted photovoltaic modules can also supply power to the grid, further reducing the power loss of the grid.

[0101] In one embodiment, at least some of the subsequent snow melting control commands indicate a number of photovoltaic modules to be heated for snow melting that is greater than the number of photovoltaic modules to be heated for snow melting indicated by the previous subsequent snow melting control command.

[0102] This can be achieved by specifying that the number of photovoltaic (PV) modules to be heated for melting snow in each subsequent snow melting control command is always greater than the number indicated by the previous subsequent snow melting control command by a fixed amount. Alternatively, it can be that some subsequent snow melting control commands specify that the number of PV modules to be heated for melting snow is the same as the number indicated by the previous subsequent snow melting control command, but the number indicated by some subsequent snow melting control commands is greater than the number indicated by the previous subsequent snow melting control command by a preset amount. The preset amount can be set according to needs and can be one, two, three, four, etc., without any restrictions.

[0103] For example, the second subsequent snow melting control command indicates that the number of photovoltaic modules to be heated for snow melting is one more than the number indicated by the first subsequent snow melting control command; the third subsequent snow melting control command indicates that the number of photovoltaic modules to be heated for snow melting is one more than the number indicated by the second subsequent snow melting control command; and so on, with each subsequent command indicating that the number of photovoltaic modules to be heated for snow melting is one more than the number indicated by the previous subsequent snow melting control command. In another example, the number of photovoltaic modules to be melted by the first subsequent snow melting control command is the same as the number of photovoltaic modules to be melted by the first snow melting control command. The number of photovoltaic modules to be melted by the second subsequent snow melting control command is a preset number more than the number of photovoltaic modules to be melted by the first subsequent snow melting control command. The number of photovoltaic modules to be melted by the third subsequent snow melting control command is the same as the number of photovoltaic modules to be melted by the first snow melting control command, and so on, until the target number of photovoltaic modules is melted.

[0104] By limiting the number of photovoltaic modules awaiting snow melting to be heated and melted by at least some subsequent snow melting control commands to be greater than the number of photovoltaic modules awaiting snow melting to be heated and melted by the previous subsequent snow melting control command, the snow melting speed of the already melted photovoltaic modules and the photovoltaic modules awaiting snow melting can be increased, the snow melting efficiency can be improved, the snow melting time can be shortened, and the time interval between the photovoltaic system generating electricity to supply power to the grid can be further shortened.

[0105] In one embodiment, the subsequent snow melting control command carries a current threshold.

[0106] If the current value generated by the already melted photovoltaic modules is less than or equal to the current threshold, the subsequent snow melting control command is used to instruct the third part of the current generated by the already melted photovoltaic modules to heat and melt the snow on y photovoltaic modules to be melted.

[0107] The third part of the current can be the total current value generated by the photovoltaic modules after the snow has melted, or it can be a portion of the generated current value; there is no restriction on this.

[0108] Understandably, if the current generated by the already melted snow photovoltaic modules is less than or equal to the current threshold, and the current generated by the already melted snow photovoltaic modules is insufficient to simultaneously supply power to the photovoltaic modules waiting to melt snow and the grid, prioritizing the supply to the photovoltaic modules waiting to melt snow can increase the number of already melted snow photovoltaic modules and provide more power to the grid.

[0109] In one embodiment, the subsequent snow melting control command carries an identifier for the component to be melted, which indicates any of the following:

[0110] The module awaiting snow melting is identified as the yth photovoltaic module closest to the photovoltaic module that has already had its snow melted.

[0111] The modules awaiting snow melting are identified as the yth photovoltaic modules with the highest historical power generation.

[0112] In one possible embodiment, the control terminal stores an electronic layout diagram of the photovoltaic system. This diagram records the location coordinates and circuit topology of each photovoltaic module, such as which bidirectional DC-DC converter each module is connected to. Based on the electronic layout diagram and real-time and historical monitoring data corresponding to the photovoltaic modules, the control terminal can determine the power generation and snow cover status of each photovoltaic module, thereby identifying the photovoltaic module closest to those whose snow has already melted and which needs to be melted.

[0113] In one possible embodiment, data can be monitored in real time using sensors. These sensors can be, for example, sensors integrated into the photovoltaic system itself. For instance, the sensors might include current transformers to acquire the output current of each photovoltaic module and irradiance sensors to acquire the corresponding light intensity of each photovoltaic module. If the irradiance sensor indicates sufficient sunlight, but the current transformer indicates that the output current of the photovoltaic module is zero or very low, it suggests that the surface of the photovoltaic module is covered by snow. Alternatively, real-time monitoring data could be pressure sensors mounted on the photovoltaic module's support structure. Based on the pressure data obtained from the pressure sensors, it can be determined whether the photovoltaic module is covered by snow and the weight of the snow. Another example is real-time monitoring data that could be inspection images of the photovoltaic system acquired by a drone or images of the photovoltaic system captured by a monitoring camera. Based on these images, image recognition algorithms can be used to identify white snow areas in the images, and combined with an electronic layout diagram, the snow coverage of each photovoltaic module can be determined.

[0114] In one possible embodiment, historical monitoring data could be the DC voltage and DC current output of each photovoltaic module before the current snow melt. The historical power generation of each photovoltaic module can be obtained from the output DC voltage and DC current. When a bidirectional DC-AC converter is connected to multiple photovoltaic modules, the total DC current and total DC voltage output by the multiple photovoltaic modules can be directly monitored to obtain the total historical power generation. Alternatively, the total historical power generation can be obtained by combining the historical power generation data of each photovoltaic module.

[0115] When a subsequent snow melting control command carries an identifier for a component to be melted, the subsequent snow melting control command is used to instruct the use of the current generated by at least one already melted photovoltaic module to heat and melt the snow on the photovoltaic modules corresponding to the identifiers of the y components to be melted.

[0116] In this embodiment, the target photovoltaic module to be melted can be determined based on the identifier of the module to be melted. The subsequent snow melting control command carrying the identifier of the module to be melted is sent to the bidirectional DC-AC converter connected to the target photovoltaic module. The bidirectional DC-AC converter operates based on the subsequent snow melting control command, so that the current generated by the photovoltaic module that has melted snow can be fed back to the target photovoltaic module to achieve heating and snow melting.

[0117] Prioritizing the heating and snow-melting of photovoltaic (PV) modules with the highest historical power generation can quickly restore the main power generation capacity to provide more electricity to the PV modules awaiting snow melting, thus achieving rapid snow melting and reducing power generation losses. Prioritizing the snow melting of PV modules closest to those already melted can reduce losses along the power transmission path and improve the energy utilization rate of the already melted PV modules.

[0118] In one embodiment, the first snow melting control command and / or subsequent snow melting control command carries a first phase shift angle reversal command, which instructs the bidirectional DC-AC converter to perform a phase shift angle reversal according to the first phase shift angle reversal command.

[0119] The phase shift angle controls the direction and magnitude of power flow in the bidirectional DC-AC converter. When the grid voltage leads the photovoltaic module voltage by a certain angle, energy flows from the grid to the photovoltaic module, i.e., reverse power flow. When the grid voltage lags the photovoltaic module voltage by a certain angle, energy flows from the photovoltaic module to the grid.

[0120] When snow melting is required, the bidirectional DC-AC converter, based on the first snow melting control command and / or the first phase angle reversal command carried by the subsequent snow melting control command, changes the direction of energy flow from the photovoltaic module side to the photovoltaic module side, thereby realizing the heating and snow melting of the photovoltaic module to be melted by the current on the grid side or the current generated by the photovoltaic module that has already melted snow.

[0121] In one embodiment, this application provides a snow melting method for a photovoltaic system, see [link to relevant documentation]. Figure 1 and Figure 2 The photovoltaic system is connected to the grid and includes multiple photovoltaic modules and multiple bidirectional DC-AC converters. The method is applied to any one of the bidirectional DC-AC converters. See [link to relevant documentation]. Figure 9 The method includes steps S202 and S204.

[0122] In step S202, the bidirectional DC-AC converter acquires a first sub-instruction from the first snow melting control command, and in response to the first sub-instruction, uses the AC current of the power grid to heat and melt the snow on at least one photovoltaic module to be melted.

[0123] The first snow melting control command includes *a* first sub-commands, each corresponding to a bidirectional DC-AC converter. That is, the bidirectional DC-AC converter currently receives the first sub-command from the first snow melting control command. In response to the first sub-command, the bidirectional DC-AC converter uses the AC current from the grid to heat and melt the snow from at least one photovoltaic module to be melted.

[0124] When a bidirectional DC-AC converter is connected to a single photovoltaic (PV) module, the first sub-command controls the use of AC current from the grid to heat and melt the snow on the PV module. When a bidirectional DC-AC converter is connected to multiple PV modules, the first sub-command controls the use of AC current from the grid to heat and melt the snow on the multiple PV modules.

[0125] In step S204, the bidirectional DC-AC converter obtains a second sub-instruction from the subsequent snow melting control instructions. In response to the second sub-instruction, it uses the current generated by at least one photovoltaic module that has already melted snow to heat and melt the snow on at least one photovoltaic module to be melted.

[0126] It is understandable that when the snow melting method of a photovoltaic system is applied to a bidirectional DC-AC converter, the bidirectional DC-AC converter can receive a first snow melting control command; or, the bidirectional DC-AC converter can receive subsequent snow melting control commands.

[0127] Each subsequent snow melting control command includes b second sub-commands, and each second sub-command corresponds to a bidirectional DC-AC converter.

[0128] When a bidirectional DC-AC converter is connected to a single photovoltaic (PV) module, the second subcommand controls the use of AC current from the grid to heat and melt the snow on the PV module. When a bidirectional DC-AC converter is connected to multiple PV modules, the second subcommand controls the use of AC current from the grid to heat and melt the snow on multiple PV modules.

[0129] The subsequent snow melting control command is used to control the remaining bidirectional DC-AC converters other than the one corresponding to the first snow melting control command, after the first snow melting control command instructs at least one bidirectional DC-AC converter to operate and at least one photovoltaic module has been found to have melted snow. See the previous example for details, which will not be repeated here.

[0130] In this embodiment of the application, a bidirectional DC-AC converter can only be used to acquire one of the first snow melting control command (first sub-command) and the subsequent snow melting control command (second sub-command) within one cycle. That is, a bidirectional DC-AC converter can only be used to execute one of steps S202 and S204. One cycle refers to a cycle that may experience one snow cover and one snow melting, such as 8 hours, 12 hours, 24 hours, etc., and is not limited here.

[0131] The aforementioned snow-melting method for photovoltaic (PV) systems converts alternating current from the power grid into direct current to heat and melt snow from at least one PV module. This limits the amount of grid-side energy used for initial snow melting, effectively controlling energy consumption by non-PV systems. After obtaining the PV modules with melted snow, the current generated by these modules is used to heat and melt the remaining snow. This process is repeated until the target number is reached. This allows the energy generated by the PV system to heat and melt snow from the PV modules within the system, further reducing energy consumption by non-PV systems. In other words, it enables the use of relatively small grid energy as initial energy to drive the PV system to heat and melt snow based on its own generated energy, reducing energy consumption beyond what is generated by the PV system itself.

[0132] In one embodiment, the subsequent snow melting control command carries a current threshold.

[0133] If the current generated by the already melted snow photovoltaic modules exceeds the current threshold, the first portion of the current generated by the already melted snow photovoltaic modules is used to heat and melt the snow in the photovoltaic modules to be melted. The second portion of the current is used to transmit to the grid or energy storage equipment.

[0134] If the current generated by the already melted photovoltaic module is less than or equal to the current threshold, the third part of the current generated by the already melted photovoltaic module is used to heat and melt the snow on the photovoltaic module to be melted.

[0135] The setting methods for the first part current, the second part current, the third part current, and the current threshold have been described in detail in the previous embodiments and will not be repeated here.

[0136] If the current generated by the already melted photovoltaic (PV) modules is less than or equal to the current threshold, power is prioritized to the PV modules awaiting snow melting. If the current generated by the already melted PV modules is greater than the current threshold, power is partially supplied to the PV modules awaiting snow melting, and partially supplied to the grid or energy storage devices. This maximizes the utilization of the electricity generated by the already melted PV modules to accelerate the snow melting process, achieving rapid snow melting while minimizing the energy supplied by the grid or energy storage devices.

[0137] In one embodiment, subsequent snow melting control commands carry an identifier for a snow melting component, the snow melting component identifier indicating any of the following:

[0138] The module awaiting snow melting is the photovoltaic module closest to the one that has already had its snow melted.

[0139] The modules awaiting snow melting are the photovoltaic modules with the highest historical power generation.

[0140] In this embodiment, the target photovoltaic module to be melted can be determined based on the module identifier. A subsequent snow-melting control command carrying the module identifier is sent to a bidirectional DC-AC converter connected to the target photovoltaic module. This bidirectional DC-AC converter operates based on the subsequent snow-melting control command, allowing the current generated by the already melted photovoltaic module to flow back to the target photovoltaic module, thereby achieving snow melting through heating. The foregoing embodiments have been described in detail and will not be repeated here.

[0141] In one embodiment, the first snow melting control command and / or subsequent snow melting control command carries a first phase shift angle reversal command, which instructs the bidirectional DC-AC converter to perform a phase shift angle reversal according to the first phase shift angle reversal command.

[0142] The specific limitations are as described in the foregoing embodiments, and will not be repeated here.

[0143] In one embodiment, after heating and melting the photovoltaic modules to be melted in response to a first sub-instruction or a second sub-instruction, the method further includes:

[0144] Obtain power generation control commands; in response to the power generation control commands, transmit the current generated by the snow-melted photovoltaic modules to the photovoltaic modules to be melted and / or the power grid.

[0145] For example, the power generation control command carries a second phase shift angle reversal command. This second phase shift angle reversal command instructs the bidirectional DC-AC converter to reverse the phase shift angle according to the command. Specifically, based on the power generation control command carrying the second phase shift angle reversal command, the bidirectional DC-AC converter changes the energy flow from the photovoltaic module side to the photovoltaic module side. It can determine whether the current generated by the photovoltaic module is transmitted to the photovoltaic module awaiting snow melting or to the grid based on the current value generated by the photovoltaic module. If there are no photovoltaic modules awaiting snow melting, the current is transmitted to the grid. If there are photovoltaic modules awaiting snow melting, and the generated current value is less than or equal to a current threshold, all current is transmitted to the photovoltaic modules awaiting snow melting. If there are photovoltaic modules awaiting snow melting, and the generated current value is greater than the current threshold, part of the current is transmitted to the photovoltaic modules awaiting snow melting, and the remaining part is transmitted to the grid.

[0146] In another example, if the energy flow direction of the photovoltaic module has changed to flow out from the photovoltaic side before the power generation control command is obtained, the power generation control command does not need to carry the second phase shift angle reversal command. The photovoltaic module generates electricity based on the power generation control command, and determines the flow direction of the current generated by the photovoltaic module according to the condition of the photovoltaic module to be melted and the current value of the generated current. The foregoing embodiments have been described in detail and will not be repeated here.

[0147] By limiting the current generated by the already melted snow-covered photovoltaic (PV) modules to heat the remaining PV modules for snow melting, the energy drawn from the grid can be reduced, thereby reducing energy loss on the grid side. Furthermore, transmitting the current generated by the already melted snow-covered PV modules back to the grid can also enable power supply to the grid.

[0148] In one embodiment, a snow melting method for a photovoltaic system is provided, the photovoltaic system including multiple bidirectional DC-AC converters and multiple photovoltaic modules. For example... Figure 1 or Figure 2 As shown, the DC terminal of the bidirectional DC-AC converter is connected to at least one photovoltaic module, and the AC terminal of the bidirectional DC-AC converter is used for connection to the power grid. The photovoltaic system also includes a gateway controller, which is connected to each bidirectional DC-AC converter. The gateway controller is also communicatively connected to a control terminal. The gateway controller can send the first snow melting control command and subsequent snow melting control commands sent by the control terminal to different bidirectional DC-AC converters. This method is used in the gateway controller.

[0149] See Figure 10 The snow melting method of the photovoltaic system includes steps S302 to S304.

[0150] In step S302, the gateway controller obtains the first snow melting control command, which instructs a bidirectional DC-AC converters to use the AC current from the grid to heat and melt the snow on x photovoltaic modules to be melted.

[0151] In step S304, the gateway controller obtains at least one subsequent snow melting control instruction. The subsequent snow melting control instruction is used to instruct b bidirectional DC-AC converters to use at least a portion of the current generated by at least one photovoltaic module that has already melted snow to heat and melt the snow on y photovoltaic modules to be melted snow, until the number of photovoltaic modules that have already melted snow reaches the target number.

[0152] The target quantity can be the total number of photovoltaic modules awaiting snow melting, or the number of photovoltaic modules requiring snow melting based on demand; no limitation is imposed here. Subsequent snow melting control commands are commands used to control the remaining bidirectional DC-AC converters (excluding the one corresponding to the first snow melting control command) after the first snow melting control command has instructed one bidirectional DC-AC converter to operate and at least one photovoltaic module has been melted. The foregoing embodiments have been described in detail and will not be repeated here.

[0153] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least the first part of the steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least the first part of steps or stages in other steps. It is understood that the steps in different embodiments can be freely combined as needed, and all non-contradictory solutions formed by such combinations are within the scope of protection of this application.

[0154] It is understood that the term "based on" as used in this application is used to describe one or more factors that influence the determination, but does not exclude other factors that may influence the determination. For example, the phrase "determine A based on B" means that the determination of A can be based entirely or at least partially on factor B. That is, B is a factor that influences the determination of A, but does not exclude the fact that the determination of A is also based on C.

[0155] Based on the same inventive concept, this application also provides a photovoltaic system for implementing the snow melting method of the photovoltaic system described above. The solution provided by this photovoltaic system is similar to the solution described in the above method; therefore, the specific limitations in one or more photovoltaic system embodiments provided below can be found in the limitations of the snow melting method of the photovoltaic system described above, and will not be repeated here.

[0156] In one embodiment, a photovoltaic system is provided, see [link to relevant documentation]. Figure 1 and Figure 2 The photovoltaic system is connected to the power grid and includes multiple photovoltaic modules and multiple bidirectional DC-AC converters, with one bidirectional DC-AC converter corresponding to at least one photovoltaic module.

[0157] A bidirectional DC-AC converter is used to acquire a first sub-instruction from a first snow melting control command, and in response to the first sub-instruction, uses the AC current from the grid to heat and melt the snow on at least one photovoltaic module to be melted.

[0158] The first snow melting control command includes a first sub-commands, each of which corresponds to a bidirectional DC-AC converter.

[0159] The bidirectional DC-AC converter is used to acquire a second sub-instruction in the subsequent snow melting control command. In response to the second sub-instruction, the current generated by at least one already melted photovoltaic module is used to heat and melt the snow on the photovoltaic module to be melted.

[0160] Each subsequent snow melting control command includes b second sub-commands, and each second sub-command corresponds to a bidirectional DC-AC converter.

[0161] The subsequent snow melting control command is a command used to control the remaining bidirectional DC-AC converters other than the bidirectional DC-AC converter corresponding to the first snow melting control command, after the first snow melting control command instructs at least one bidirectional DC-AC converter to operate and at least one photovoltaic module with melted snow is obtained.

[0162] As mentioned earlier, a bidirectional DC-AC converter can only acquire one of the first snow melting control command and the subsequent snow melting control command within one cycle, which will not be elaborated here.

[0163] The aforementioned photovoltaic system converts alternating current from the power grid into direct current to heat and melt snow from at least one photovoltaic module to be melted. This limits the amount of grid-side energy used for initial snow melting, thereby effectively controlling energy consumption by non-photovoltaic systems. After obtaining the melted photovoltaic modules, the current generated by these modules is used to heat and melt the remaining snow from the photovoltaic modules to be melted. This process is repeated until the target number is reached. This allows the energy generated by the photovoltaic system to heat and melt snow from the photovoltaic modules within the system, further reducing energy consumption by non-photovoltaic systems. In other words, it achieves the use of relatively small grid energy as initial energy to drive the photovoltaic system to heat and melt snow based on its own generated energy, reducing energy consumption other than that generated by the photovoltaic system.

[0164] In one embodiment, the circuit topology of the bidirectional DC-AC converter is a resonant dual active bridge circuit topology.

[0165] Please refer to the following: Figure 11 The bidirectional DC-AC converter includes a DC-side conversion circuit 210, a transformer 220, an AC-side conversion circuit 230, and a resonant capacitor C1. The resonant capacitor is located on the DC side of the bidirectional DC-AC converter, or, alternatively, on the AC side (e.g.,...). Figure 11 (As shown). In one possible implementation, the resonant capacitor and the transformer leakage inductance form an LC resonant cavity; in another possible implementation, the bidirectional DC-AC converter includes a separate resonant inductor L1, which, together with the resonant capacitor C1, forms an LC resonant cavity, exemplarily, such as... Figure 12 , Figure 13 or Figure 14 As shown.

[0166] A bidirectional DC-AC converter employing a resonant dual active bridge circuit topology can achieve soft switching across the entire load range, reducing turn-on losses and voltage spikes in the switching transistors during operation and improving the converter's efficiency. Furthermore, this topology reduces electromagnetic interference, suppresses DC bias and current stress, thereby increasing power density and switching efficiency.

[0167] In one embodiment, the bidirectional DC-AC converter includes a DC-side conversion circuit, a transformer, and an AC-side conversion circuit. The DC-side conversion circuit includes a first full-bridge conversion circuit, and the AC-side conversion circuit includes a bidirectional switched half-bridge conversion circuit.

[0168] Please refer to Figure 12 and Figure 13 The first full-bridge converter circuit includes switches Q1, Q2, Q3, and Q4. The upper bridge arm of the bidirectional switching half-bridge converter circuit includes a bidirectional switch composed of switches Q5 and Q6, and the lower bridge arm includes a bidirectional switch composed of switches Q7 and Q8. Optionally, such as... Figure 6 As shown, the AC-side conversion circuit also includes a capacitor bridge arm circuit, which includes two capacitors C2 and C3 connected in series. One end of the AC-side winding of the transformer is connected to the midpoint of the bridge arm of the bidirectional switching conversion circuit, and the other end is connected to the midpoint of the capacitor bridge arm circuit. Capacitor C4 is a filter capacitor between the AC-side conversion circuit and the power grid. Optionally, as... Figure 8 As shown, one end of the AC winding of the transformer is connected to the midpoint of the bridge arm of the bidirectional switch bridge arm circuit, and the other end of the AC winding of the transformer is connected to one end of the two ends of the bidirectional switch bridge arm circuit; wherein, capacitor C5 is the filter capacitor between the AC side conversion circuit and the power grid.

[0169] It should be noted that the midpoint position in the embodiments of this application does not refer to the midpoint of physical distance, but rather to the midpoint position in electrical relationship, such as... Figure 12 and Figure 13 In a bidirectional switching converter circuit, the midpoint refers to any point on the circuit between the upper and lower bridge arm circuits where power can be supplied.

[0170] In one embodiment, the bidirectional DC-AC converter includes a DC-side conversion circuit, a transformer, and an AC-side conversion circuit. The DC-side conversion circuit includes a first full-bridge conversion circuit, and the AC-side conversion circuit includes a second full-bridge conversion circuit and a power frequency switching circuit. The first terminal of the second full-bridge conversion circuit is connected to the transformer, and the second terminal of the second full-bridge conversion circuit is connected to the first terminal of the power frequency switching circuit. The second terminal of the power frequency switching circuit is connected to the power grid.

[0171] like Figure 14 As shown, the first full-bridge converter circuit includes transistors Q1, Q2, Q3, and Q4; the second full-bridge converter circuit includes transistors Q9, Q10, Q11, and Q12; and the power frequency switching circuit includes transistors Q13, Q14, Q15, and Q16. Capacitor C6 is the filter capacitor between the second full-bridge converter circuit and the power frequency switching circuit.

[0172] In one embodiment, a bidirectional DC-AC converter is also provided for use with Figure 1 or Figure 2 In the photovoltaic system shown, the DC terminal of a bidirectional DC-AC converter is connected to at least one photovoltaic module, and the AC terminal of the bidirectional DC-AC converter is used to connect to the power grid. The bidirectional DC-AC converter includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0173] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon that, when executed by a processor, implements the steps in the above-described method embodiments.

[0174] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.

[0175] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0176] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0177] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A snow melting method for a photovoltaic system, characterized in that, A photovoltaic system connected to a power grid and comprising multiple photovoltaic modules and multiple bidirectional DC-AC converters, wherein one of the bidirectional DC-AC converters corresponds to at least one of the photovoltaic modules, the method comprising: Generate a first snow melting control command; the first snow melting control command is used to instruct a of the bidirectional DC-AC converters to use the AC current of the power grid to heat and melt the snow on x photovoltaic modules to be melted; In response to the fact that the photovoltaic modules to be melted have been melted, at least one subsequent snow melting control command is generated; the subsequent snow melting control command is used to instruct b of the bidirectional DC-AC converters to use at least a portion of the current generated by at least one melted photovoltaic module to heat and melt the y photovoltaic modules to be melted until the number of melted photovoltaic modules reaches the target number. The subsequent snow melting control command is a command used to control the remaining bidirectional DC-AC converters other than the bidirectional DC-AC converter corresponding to the first snow melting control command, after the first snow melting control command instructs at least one of the bidirectional DC-AC converters to operate and at least one photovoltaic module with melted snow is obtained.

2. The method according to claim 1, characterized in that, The first snow melting control command is an instruction in the photovoltaic system to control at least one of the bidirectional DC-AC converters. The first snow melting control command includes a first sub-instructions, each of which corresponds to one of the bidirectional DC-AC converters. Each of the subsequent snow melting control commands includes b second sub-commands, and each second sub-command corresponds to one of the bidirectional DC-AC converters.

3. The method according to claim 1, characterized in that, x is less than or equal to a first quantity threshold, where the first quantity threshold is less than or equal to the total number of photovoltaic modules in the photovoltaic system that are awaiting snow melting.

4. The method according to claim 1, characterized in that, The subsequent snow melting control command carries a current threshold. In response to the fact that the photovoltaic modules to be melted have already melted, at least one subsequent snow-melting control command is generated; the subsequent snow-melting control command is used to instruct b of the bidirectional DC-AC converters to use at least a portion of the current generated by at least one of the melted photovoltaic modules to heat and melt the y photovoltaic modules to be melted, including: The quantity of y is determined based on the ratio of the current value generated by the photovoltaic module after snow melting to the current threshold. If the current value generated by the photovoltaic modules that have already melted snow is greater than the current threshold, the subsequent snow melting control command uses the first part of the current generated by the photovoltaic modules that have already melted snow to heat the y photovoltaic modules that need to be melted snow; and transmits the second part of the current generated by the photovoltaic modules that have already melted snow to the power grid.

5. The method according to claim 1, characterized in that, At least a portion of the subsequent snow melting control command indicates that the number of photovoltaic modules to be heated for snow melting is greater than the number of photovoltaic modules to be heated for snow melting indicated by the previous subsequent snow melting control command.

6. The method according to claim 1, characterized in that, The subsequent snow melting control command carries a current threshold. If the current value generated by the photovoltaic modules that have already melted snow is less than or equal to the current threshold, the subsequent snow melting control command is used to instruct the third part of the current generated by the photovoltaic modules that have already melted snow to be used to heat and melt the snow on y photovoltaic modules that need to be melted.

7. The method according to any one of claims 1 to 6, characterized in that, The subsequent snow melting control command carries an identifier for the component to be melted, which indicates any of the following: The components to be melted are identified as the y photovoltaic components closest to the photovoltaic components that have already had their snow melted; The components to be melted are identified as the y photovoltaic modules with the highest historical power generation. The subsequent snow melting control command is used to instruct the use of the current generated by at least one already melted photovoltaic module to heat and melt the snow on the y photovoltaic modules corresponding to the snow melting module identifiers.

8. A snow melting method for a photovoltaic system, characterized in that, The photovoltaic system is connected to the power grid and includes multiple photovoltaic modules and multiple bidirectional DC-AC converters, each bidirectional DC-AC converter corresponding to at least one photovoltaic module. The method is applied to any one of the bidirectional DC-AC converters, and the method includes: Obtain a first sub-instruction from the first snow melting control command; in response to the first sub-instruction, use the alternating current of the power grid to heat and melt the snow on at least one photovoltaic module to be melted; the first snow melting control command includes a first sub-instructions, each first sub-instruction corresponding to one of the bidirectional DC-AC converters; or... Obtain a second sub-instruction from a subsequent snow melting control instruction; in response to the second sub-instruction, use the current generated by at least one photovoltaic module that has already melted snow to heat and melt the snow on at least one photovoltaic module to be melted; each of the subsequent snow melting control instructions includes b second sub-instructions, and each second sub-instruction corresponds to one of the bidirectional DC-AC converters; The subsequent snow melting control command is a command used to control the remaining bidirectional DC-AC converters other than the bidirectional DC-AC converter corresponding to the first snow melting control command, after the first snow melting control command instructs at least one of the bidirectional DC-AC converters to operate and at least one photovoltaic module with melted snow is obtained.

9. The method according to claim 8, characterized in that, In the case of including the subsequent snow melting control command, the subsequent snow melting control command carries a current threshold. If the current value generated by the photovoltaic module that has already melted snow is greater than the current threshold, the first portion of the current generated by the photovoltaic module that has already melted snow is used to heat and melt the snow in the at least one photovoltaic module that needs to be melted; or... If the current value generated by the photovoltaic module that has already melted snow is less than or equal to the current threshold, the third portion of the current generated by the photovoltaic module that has already melted snow is used to heat and melt the snow on at least the photovoltaic module that needs to be melted.

10. The method according to claim 8, characterized in that, After heating and melting the photovoltaic modules to be melted in response to the first sub-instruction or the second sub-instruction, the method further includes: Obtain a power generation control command; in response to the power generation control command, transmit a second portion of the current generated by the snow-melted photovoltaic module to the photovoltaic module to be melted and / or the power grid.

11. A photovoltaic system, characterized in that, The photovoltaic system is connected to the power grid and includes multiple photovoltaic modules and multiple bidirectional DC-AC converters, with one bidirectional DC-AC converter corresponding to at least one photovoltaic module. The bidirectional DC-AC converter is used to acquire a first sub-instruction from the first snow melting control command, and in response to the first sub-instruction, uses the AC current from the power grid to heat and melt the snow on at least one photovoltaic module to be melted; the first snow melting control command includes a first sub-instructions, each first sub-instruction corresponding to one of the bidirectional DC-AC converters; or... The bidirectional DC-AC converter is used to acquire a second sub-instruction in the subsequent snow melting control command. In response to the second sub-instruction, the current generated by at least one photovoltaic module that has already melted the snow is used to heat and melt the snow on at least one photovoltaic module to be melted. Each subsequent snow melting control command includes b second sub-instructions, and each second sub-instruction corresponds to one bidirectional DC-AC converter. The subsequent snow melting control command is a command used to control the remaining bidirectional DC-AC converters other than the bidirectional DC-AC converter corresponding to the first snow melting control command, after the first snow melting control command instructs at least one of the bidirectional DC-AC converters to operate and at least one photovoltaic module with melted snow is obtained.

12. The photovoltaic system according to claim 11, characterized in that, The circuit topology of the bidirectional DC-AC converter is a resonant dual active bridge circuit topology.

13. The photovoltaic system according to claim 12, characterized in that, The bidirectional DC-AC converter includes a DC-side conversion circuit, a transformer, and an AC-side conversion circuit. The DC-side conversion circuit includes a first full-bridge conversion circuit, and the AC-side conversion circuit includes a bidirectional switched half-bridge conversion circuit.

14. The photovoltaic system according to claim 12, characterized in that, The bidirectional DC-AC converter includes a DC-side conversion circuit, a transformer, and an AC-side conversion circuit. The DC-side conversion circuit includes a first full-bridge conversion circuit, and the AC-side conversion circuit includes a second full-bridge conversion circuit and a power frequency switching circuit. The first terminal of the second full-bridge conversion circuit is connected to the transformer, the second terminal of the second full-bridge conversion circuit is connected to the first terminal of the power frequency switching circuit, and the second terminal of the power frequency switching circuit is connected to the power grid.

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