Inverter and photovoltaic system

Abstract

The present application provides a power line communication apparatus, comprising a first modulation circuit configured in a first power device, a second modulation circuit configured in a second power device, and a grounding grid, wherein the first power device and the second power device are connected by means of power lines, the first modulation circuit and the second modulation circuit are coupled to the grounding grid respectively by means of a first signal coupling device and a second signal coupling device, and a modulation signal coupled by the first modulation circuit is transmitted to the second modulation circuit by means of the power lines and the grounding grid. The grounding grid which does not transmit electric energy is used as a signal transmission channel, such that no large current is generated, thereby improving the reliability of signal transmission.

Description

Inverter and photovoltaic system

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on September 4, 2023, with application number 202322405932.1 and application name “A power line communication device, power equipment and photovoltaic system”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The embodiments of the present application relate to power line communication technology, and more particularly to an inverter and a photovoltaic system. Background Art

[0004] With the development of power electronics, the use of alternative energy sources to generate electricity has become widespread. Existing solar photovoltaic systems typically include various power generation and conversion devices, such as DC power generators (e.g., photovoltaic arrays) and inverters. These devices are often separated by significant distances (e.g., a DC power generator and inverter are 1 km apart). For signal exchange between these devices, PLC (power line communication) is often used.

[0005] In PLC signal transmission, magnetic rings are often placed on power lines to couple signals to the power lines, or to increase the input and output impedance between two power lines to reduce signal attenuation. Power lines, while transmitting modulated signals, typically also transmit electrical energy. This energy typically carries a high current. Under high current conditions, the magnetic induction intensity of the magnetic ring quickly reaches its maximum value, leading to magnetic saturation. This significantly reduces the inductance of the magnetic ring, resulting in PLC signal attenuation and reduced signal transmission reliability. Therefore, improving the reliability of PLC signal transmission in power line communication devices has become a challenge.

[0006] Utility Model Content

[0007] The present application provides a power line communication device for communicating between multiple power devices, using a grounding grid and power cables to construct a differential transmission channel to transmit PLC signals. Since the grounding grid itself does not transmit electrical energy, using the grounding grid as a signal transmission channel will not generate large currents, which can effectively reduce the safety regulations, capacitance or volume requirements of signal coupling devices, improve the reliability of the transmitted signals, and save space and costs of the power system.

[0008] In a first aspect, a power line communication device is provided, which includes a first modulation circuit arranged on a first power device, a second modulation circuit arranged on a second power device, a first signal coupling device arranged on the first power device side, and a second signal coupling device arranged on the second power device side, wherein the first signal coupling device and the second signal coupling device are any one of a magnetic ring, an inductor and a capacitor; the first power device and the second power device are connected through a power line; the first signal coupling device and the second signal coupling device are respectively coupled to a ground grid; the power line located on one side of the first power device is coupled to the ground grid through the first signal coupling device, and the power line located on the side of the second power device is coupled to the ground grid through the second signal coupling device; the modulation signal coupled by the first modulation circuit is transmitted to the second modulation circuit through the power line and the ground grid.

[0009] In the above embodiment of the present application, by coupling the signal coupling device to the grounding grid, since the grounding grid does not transmit electrical energy, or in other words, the current value in the grounding grid is usually small, no large current will be generated at the signal coupling device. When capacitive coupling is used, the above setting has no requirements for safety regulations, capacitance, etc. for the design of the capacitor. And when electromagnetic coupling is used, the above setting will not generate a large current, thereby causing the inductance of the magnetic ring or inductor to drop sharply, thereby causing signal attenuation. Therefore, the above setting can enhance the stability of PLC signal transmission. And the requirements for the volume or capacity, safety regulations, etc. of the signal coupling device are reduced, thereby saving the original component cost of the power equipment, reducing the volume space, and improving the safety performance of the power equipment.

[0010] In conjunction with the first aspect, in one implementation of the first aspect, the input / output terminals of the first modulation circuit are coupled to the first signal coupling device; the modulated signal is coupled to the power line and the ground grid via the first signal coupling device, and is transmitted from the first power device to the second power device. A signal loop is formed between the ground grid and the power line, completing signal transmission between the first power device and the second power device. During signal transmission, no large current is generated at the signal coupling device, thereby enhancing the transmission stability of the PLC signal.

[0011] In combination with the first aspect, in an implementation of the first aspect, the input / output end of the second modulation circuit is coupled to the second signal coupling device; the second modulation circuit receives the modulation signal from the ground grid and the power line through the second signal coupling device.

[0012] In conjunction with the first aspect, in one implementation of the first aspect, the first signal coupling device and the second signal coupling device are both magnetic rings; the first input / output terminal of the first modulation circuit is connected to the second input / output terminal of the first modulation circuit through the first signal coupling device, and the first input / output terminal of the second modulation circuit is connected to the second input / output terminal of the second modulation circuit through the second signal coupling device; the ground wire of the first power device passes through the first signal coupling device, and the ground wire of the second power device passes through the second signal coupling device. By placing the magnetic ring or inductor coupled to a ground grid that does not transmit electrical energy, the magnetic saturation speed of the magnetic ring can be effectively reduced, thereby maintaining a high inductance of the magnetic ring, reducing the attenuation of the PLC signal, and improving the reliability of PLC signal transmission.

[0013] In conjunction with the first aspect, in one implementation of the first aspect, the first signal coupling device and the second signal coupling device are respectively coupled to the power line via capacitors. The capacitors serve as signal transmission channels between the signal coupling devices and the power line, improving the stability of signal transmission.

[0014] In combination with the first aspect, in one implementation of the first aspect, the power line includes at least two cables; the first signal coupling device and the second signal coupling device are coupled to the same cable of the at least two cables via a first capacitor and a second capacitor, respectively, wherein the same cable is one or more cables of the at least two cables. The first capacitor and the second capacitor can serve as signal channels, and can respectively transmit the modulated signal of the first signal coupling device and to the power line, or receive the modulated signal from the power line. The distributed capacitance, distributed inductance, etc. of each power line can be reduced, which is conducive to improving the stability of the debugging signal.

[0015] In combination with the first aspect, in an implementation of the first aspect, the first power device is an MPPT junction box, the second power device is an inverter, the power line is used to transmit DC power, the first signal coupling device and the second signal coupling device are both magnetic rings, and the first signal coupling device and the second signal coupling device are coupled to the positive cable in the power line through a first capacitor and a second capacitor, respectively.

[0016] In combination with the first aspect, in an implementation of the first aspect, the first power device is an MPPT junction box, the second power device is an inverter, the power line is used to transmit DC power, the first signal coupling device and the second signal coupling device are both magnetic rings, and the first signal coupling device and the second signal coupling device are coupled to the negative cable in the power line through a third capacitor and a fourth capacitor, respectively.

[0017] In combination with the first aspect, in an implementation of the first aspect, the first power device is a data collector, the second power device is an inverter, the power line is used to transmit AC power, the first signal coupling device and the second signal coupling device are both magnetic rings, and the first signal coupling device and the second signal coupling device are coupled to the L-phase cable in the power line through a first capacitor and a second capacitor respectively.

[0018] In combination with the first aspect, in an implementation of the first aspect, the first power device is a data collector, the second power device is an inverter, the power line is used to transmit AC power, the first signal coupling device and the second signal coupling device are both magnetic rings, and the first signal coupling device and the second signal coupling device are coupled to the N-phase cable in the power line through a third capacitor and a fourth capacitor respectively.

[0019] In combination with the first aspect, in an implementation of the first aspect, the power line includes at least two cables; the first signal coupling device and the second signal coupling device are coupled to different cables of the at least two cables through a first capacitor and a second capacitor, respectively.

[0020] The above embodiments of this application demonstrate various ways to connect signal coupling devices to power lines, demonstrating the diverse forms of the power line communication devices provided by the embodiments of this application. Furthermore, these devices can be applied to both AC and DC PLC communication scenarios, offering a wide range of flexible and secure applications.

[0021] In combination with the first aspect, in an implementation of the first aspect, the first signal coupling device and the second signal coupling device are both inductors, the first input / output terminal of the first modulation circuit is connected to one end of the first inductor, and the other end of the first inductor is connected to the ground grid, and the first input / output terminal of the second modulation circuit is connected to one end of the second inductor, and the other end of the second inductor is connected to the ground grid.

[0022] In conjunction with the first aspect, in one implementation of the first aspect, the first signal coupling device and the second signal coupling device are both capacitors; the first input / output terminal of the first modulation circuit is connected to one end of a fifth capacitor, the other end of which is coupled to the ground grid; and the first input / output terminal of the second modulation circuit is connected to one end of a sixth capacitor, which is coupled to the ground grid via the other end of the sixth capacitor. Because the signal coupling device is coupled to the ground grid, no power is transmitted through the ground grid. Therefore, the safety regulations and capacitance requirements for the capacitors in the capacitive coupling are relatively relaxed, thereby enhancing the flexibility and safety of the power equipment.

[0023] In combination with the first aspect, in an implementation of the first aspect, the second input / output terminal of the first modulation circuit and the second input / output terminal of the second modulation circuit are respectively coupled to the power line through capacitors, that is, the second input / output terminal of the first modulation circuit is connected to one end of the seventh capacitor, and the other end of the seventh capacitor is connected to the power line, and the second input / output terminal of the second modulation circuit is connected to one end of the eighth capacitor, and the other end of the eighth capacitor is connected to the power line.

[0024] In combination with the first aspect, in an implementation of the first aspect, the power line includes at least two cables; the second input / output end of the first modulation circuit and the second input / output end of the second modulation circuit are coupled to the same cable of the at least two cables through a seventh capacitor and an eighth capacitor, respectively, wherein the same cable is one or more cables of the at least two cables.

[0025] In combination with the first aspect, in an implementation of the first aspect, the first power device is an MPPT junction box, the second power device is an inverter, the power line is used to transmit DC power, and the second input / output end of the first modulation circuit and the second input / output end of the second modulation circuit are coupled to the positive cable in the power line through the seventh capacitor and the eighth capacitor respectively.

[0026] In combination with the first aspect, in an implementation of the first aspect, the first power device is an MPPT junction box, the second power device is an inverter, the power line is used to transmit DC power, and the second input / output end of the first modulation circuit and the second input / output end of the second modulation circuit are coupled to the negative cable in the power line through a seventh capacitor and an eighth capacitor, respectively.

[0027] In combination with the first aspect, in an implementation of the first aspect, the first power device is a data collector, the second power device is an inverter, the power line is used to transmit AC power, and the second input / output end of the first modulation circuit and the second input / output end of the second modulation circuit are coupled to the L-phase cable in the power line through a ninth capacitor and a tenth capacitor respectively.

[0028] In combination with the first aspect, in an implementation of the first aspect, the first power device is a data collector, the second power device is an inverter, the power line is used to transmit AC power, and the second input / output end of the first modulation circuit and the second input / output end of the second modulation circuit are coupled to the N-phase cable in the power line through a ninth capacitor and a tenth capacitor respectively.

[0029] In combination with the first aspect, in an implementation of the first aspect, the modulation circuit is coupled to the power line through a signal coupling device, and the signal coupling device is coupled to the ground grid through a capacitor, wherein the modulation circuit includes the first modulation circuit and the second modulation circuit, and the signal coupling device includes the first signal coupling device and the second signal coupling device.

[0030] In conjunction with the first aspect, in one implementation of the first aspect, when the signal coupling device is a magnetic ring, the power line includes a positive cable and a negative cable, both of which pass through the magnetic ring. Because the currents in the positive and negative cables flow in opposite directions, the magnetic fluxes generated by them can cancel each other out, thereby preventing the magnetic ring from reaching magnetic saturation, reducing PLC signal attenuation, and enhancing the reliability of PLC signal transmission. Alternatively, the power line includes an L-phase cable and an N-phase cable, with the L-phase cable passing through the magnetic ring.

[0031] In the second aspect, the present application provides an electric power device, which includes a modulation circuit, a signal coupling device and a power line, wherein the electric power device receives electric energy transmitted by other electric power devices through the power line, the modulation circuit is coupled to the ground grid through the signal coupling device, and the modulation circuit receives PLC signals transmitted by other electric power devices through the power line and the ground grid through the signal coupling device, wherein the signal coupling device is any one of a magnetic ring, an inductor and a capacitor.

[0032] In combination with the second aspect, in an implementation manner of the second aspect, the signal coupling device is a magnetic ring or an inductor, and the signal coupling device is coupled to the power line through capacitance.

[0033] In combination with the second aspect, in an implementation of the second aspect, the signal coupling device is a capacitor, the first input / output end of the modulation circuit is coupled to the ground grid through the first capacitor, and the second input / output end of the modulation circuit is coupled to the power line through the second capacitor.

[0034] In a third aspect, the present application provides a photovoltaic system comprising a plurality of power devices, wherein a power line communication device as described in the first aspect is arranged between each two of the power devices, wherein the medium and high frequency signals between each two of the power devices are transmitted using the power line erected between the two.

[0035] Specifically, the power equipment includes but is not limited to: photovoltaic components, inverters, transformers, combiner boxes, and data collectors. A power line communication device as described in the first or second aspect may be provided between the photovoltaic components and the inverter, and the medium and high frequency signals between the photovoltaic array and the inverter are transmitted using the power lines erected between the two. A power line communication device as described in the first or second aspect may be provided between the transformer and the inverter; the medium and high frequency signals between the inverter and the transformer are transmitted using the power lines erected between the two. A power line communication device as described in the first or second aspect may be provided between the photovoltaic array and the combiner box, and the medium and high frequency signals between the photovoltaic array and the combiner box are transmitted using the power lines erected between the two. A power line communication device as described in the first or second aspect may be provided between the combiner box and the inverter, and the power lines erected between the combiner box and the inverter are transmitted. The above-mentioned data monitor is used to monitor the data of the photovoltaic array and the inverter; a power line communication device as described in the first aspect or the second aspect is arranged between the data monitor and at least one of the photovoltaic array and the inverter.

[0036] The beneficial effects of the power equipment provided in the second aspect and the photovoltaic system provided in the third aspect of this application can be referred to the discussion on the beneficial effects of the first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0038] FIG1 is a schematic structural diagram of a photovoltaic system provided in an embodiment of the present application;

[0039] FIG2 is another structural schematic diagram of a photovoltaic system provided in an embodiment of the present application;

[0040] FIG3 is another structural schematic diagram of a photovoltaic system provided in an embodiment of the present application;

[0041] FIG4 is a schematic structural diagram of a power line communication device in the prior art;

[0042] FIG5 is a schematic structural diagram of a power line communication device provided in an embodiment of the present application;

[0043] FIG6 is another structural diagram of a power line communication device provided in an embodiment of the present application;

[0044] FIG7 is another structural diagram of a power line communication device provided in an embodiment of the present application;

[0045] FIG8 is another structural diagram of a power line communication device provided in an embodiment of the present application;

[0046] FIG9 is another structural diagram of a power line communication device provided in an embodiment of the present application;

[0047] FIG10 is another structural diagram of a power line communication device provided in an embodiment of the present application;

[0048] FIG11 is another structural diagram of a power line communication device provided in an embodiment of the present application;

[0049] FIG12 is another structural diagram of a power line communication device provided in an embodiment of the present application;

[0050] FIG13 is another structural diagram of a power line communication device provided in an embodiment of the present application;

[0051] FIG14 is another structural diagram of a power line communication device provided in an embodiment of the present application;

[0052] FIG15 is another structural diagram of a power line communication device provided in an embodiment of the present application;

[0053] FIG16 is another structural diagram of a power line communication device provided in an embodiment of the present application;

[0054] FIG17 is another structural diagram of a power line communication device provided in an embodiment of the present application;

[0055] FIG18 is a schematic structural diagram of an electric power device provided in an embodiment of the present application;

[0056] FIG19 is a schematic structural diagram of a photovoltaic system provided in an embodiment of the present application;

[0057] FIG20 is another structural schematic diagram of the photovoltaic system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0058] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0059] The terms "first," "second," and similar terms used herein do not denote any order, quantity, or importance, but are merely used to distinguish one component from another. Similarly, terms such as "a" or "an" do not denote a limitation of quantity, but rather denote the presence of at least one. Terms such as "connected" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0060] In the implementation of this application, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent three situations: A exists alone, A and B exist at the same time, and B exists alone.

[0061] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0062] In the description of the embodiments of the present application, unless otherwise specified, "a plurality" means two or more. For example, a plurality of cables means two or more cables; a plurality of devices means two or more devices.

[0063] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0064] Figure 1 is a schematic diagram of the structure of a photovoltaic system provided in an embodiment of the present application. The photovoltaic system shown in Figure 1 is a solar photovoltaic system. In Figure 1, the photovoltaic system includes multiple power devices, including a photovoltaic module 1, an inverter 2, a transformer 3, and a data collector 4.

[0065] Among them, the photovoltaic assembly 1 may include multiple photovoltaic assemblies, which are usually arranged in an array, also known as a photovoltaic array. Photovoltaic assemblies are battery assemblies that convert light energy into direct current electricity to generate electricity when exposed to sunlight. In specific use, photovoltaic assemblies are usually grouped to generate the required direct current electricity. The inverter 2 is used to convert the direct current electricity generated by the photovoltaic assembly into alternating current electricity. The transformer 3 is used to boost the alternating current electricity generated by the inverter 2 and input it into the power grid for power transmission. The data collector 4 is used to collect data such as the operating parameters and power output of the photovoltaic assembly 1 and the inverter 2, and then the operating status of the photovoltaic assembly 1 and the inverter 2 can be monitored based on the collected data (for example, monitoring whether the inverter 2 is working abnormally, controlling the inverter 2 to turn on or off, etc.). In this embodiment, the inverter 2 can be a string inverter or a distributed inverter. Referring to Figure 2, when the inverter 2 is a distributed inverter, an MPPT (with maximum power point tracking) junction box 5 is usually provided between the photovoltaic module 1 and the inverter 2, which is used to gather the DC power output by the photovoltaic module and output it to the inverter 2 after DC conversion, and perform the maximum power tracking function.

[0066] Figure 1 is a schematic diagram of the structure of a photovoltaic system including a string inverter, Figure 2 is a schematic diagram of the structure of a photovoltaic system including a distributed inverter, and Figure 3 is a schematic diagram of the structure of a photovoltaic system including a centralized inverter. The photovoltaic system 100 shown in Figures 1-3 also includes power lines for power transmission. Specifically, a power line 01 is provided between the photovoltaic assembly 1 and the inverter 2 shown in Figure 1 for transmitting the DC power generated by the photovoltaic assembly 1 to the inverter 2; a power line 03 is provided between the photovoltaic assembly 1 and the MPPT combiner box 5 shown in Figure 2 for transmitting the DC power generated by the photovoltaic assembly to the MPPT combiner box; and a power line 04 is provided between the MPPT combiner box 5 and the inverter 2 for transmitting the DC power aggregated by the MPPT combiner box to the inverter 2. In the photovoltaic system 100 shown in Figures 1 or 2, a power line 02 is provided between the inverter 2 and the transformer 3 for transmitting the AC power generated by the inverter 2 to the transformer 3; and a power line 05 is also provided between the data collector 4 and the inverter 2. Among them, power line 01, power line 03, and power line 04 may be DC cables, and power line 02 and power line 05 may be AC ​​cables.

[0067] In addition to power transmission, signal transmission, that is, data interaction, is usually performed between any two of the above-mentioned devices. For long-distance signal transmission between devices, that is, when the distance between the two devices is greater than 1KM, PLC (power line communication) or carrier communication is usually used for signal interaction. In other words, when the distance between any two power devices included in the photovoltaic system shown in this application is large and long-distance signal transmission is required, PLC transmission can be used. That is, after the signal to be transmitted is modulated, it is coupled to the above-mentioned power line for transmission (for example, when the power line transmits DC power, the modulated signal is coupled to the positive cable and the negative cable for transmission; when the power line transmits AC power, the modulated signal is coupled to the live wire and the neutral wire for transmission). For example, when signal transmission is performed between the MPPT junction box 5 and the inverter 2, for example, when the MPPT junction box 5 sends a signal to the inverter 2, the MPPT junction box modulates the signal and couples it to the power line 04 to transmit the signal to the inverter 2. After receiving the modulated signal, inverter 2 demodulates the modulated signal to obtain data. For example, when inverter 2 sends a signal to data collector 4, inverter 2 modulates the signal and couples it to power line 05 to transmit the signal to data collector 4. After receiving the modulated signal, data collector 4 demodulates the modulated signal to obtain data.

[0068] Among existing PLC signal transmission technologies, direct capacitor coupling is the most commonly used coupling device. Its main principle is that the inverter modulates the PLC signal and then connects it directly to the power line via a capacitor. However, this direct capacitor coupling method not only places strict requirements on capacitor selection (for example, it must meet the impedance requirements of the PLC signal on the power line and avoid excessive attenuation of the PLC signal), but also, because the voltage difference between the two power lines connected to the inverter can reach up to 1500V, the capacitor selection must also meet safety regulations to minimize the impact on the modulation circuit within the inverter.

[0069] Another existing PLC signal transmission technology uses magnetic ring coupling. As shown in Figure 4, taking the use of PLC signals between a data collector 4 and an inverter 2 as an example, a magnetic ring 10 is typically installed on one of the cables (positive or negative) of the power line 05 on the data collector 4 side. The signal input / output terminals of the data collector 4 pass through the magnetic ring, allowing the signal input / output terminals to couple to the power line 05 via the magnetic ring 10. Typically, the data collector 4 uses the power line 05 to transmit signals to the inverter 2 while also transmitting DC power. Typically, as the current passing through the magnetic ring 10 gradually increases, the magnetic flux density of the magnetic ring 10 gradually increases. Once the magnetic flux density of the magnetic ring 10 reaches a certain level, it no longer increases with increasing current. At this point, the magnetic field strength around the magnetic ring 10 continues to increase. Consequently, the magnetic permeability of the magnetic ring 10 gradually decreases. Since the inductance of the magnetic ring 10 is proportional to the magnetic permeability, the inductance of the magnetic ring 10 gradually decreases until the magnetic ring 10 reaches magnetic saturation. At this time, the inductance of the magnetic ring 10 approaches 0. However, the current transmitted in the photovoltaic system is usually high, which causes the inductance of the magnetic ring 10 to decrease sharply, thereby causing the transmitted signal to attenuate and reducing the reliability of the transmitted signal.

[0070] When PLC signal transmission is performed in a high current scenario as shown above, a magnetic ring with a high initial magnetic permeability, that is, a large inductance, is usually used. This results in a larger magnetic ring volume, high requirements on the material and process of the magnetic ring, and brings structural space pressure to the product design. In addition, the cost of the magnetic ring is high, thereby increasing the cost of PLC signal transmission and the complexity and cost of the spatial structure of the power system.

[0071] Based on the above-mentioned PLC transmission method, the power line communication device provided in this application is used for PLC signal transmission between any two power devices in the photovoltaic system 100. It should be noted that the power line communication device provided in this application is not limited to PLC signal transmission between any two devices in the photovoltaic system 100, such as the photovoltaic module 1, inverter 2, transformer 3, data collector 4, and MPPT combiner box 5, but can also be applied to PLC signal transmission between other devices included in the photovoltaic system 100 (not shown).

[0072] The power line communication device provided in this application utilizes a ground grid and power cables to construct a differential transmission channel for transmitting PLC signals. Because the ground grid itself does not transmit electrical energy, using it as a signal transmission channel eliminates the generation of high currents, effectively reducing the attenuation of the magnetic ring's permeability and improving the reliability of the transmitted signal. Furthermore, the required volume of the magnetic ring is reduced, saving space and cost in the photovoltaic system.

[0073] The power line communication device shown in this application is described in detail below through the embodiments shown in Figures 5 to 12.

[0074] In the example of PLC signal transmission between the MPPT combiner box 5 and the inverter 2 in the embodiments shown in Figures 5-12 , the power line communication device 100 includes a first modulation circuit 51, a second modulation circuit 21, power lines 041 and 042 for PLC signal transmission, a first magnetic ring L1 provided on the MPPT combiner box 5 side, and a second magnetic ring L2 provided on the inverter 2 side. The first modulation circuit 51 and the second modulation circuit 21 are respectively provided in the two power devices performing PLC signal transmission. That is, the first modulation circuit 51 can be provided in the MPPT combiner box 5, and the second modulation circuit 21 can be provided in the inverter 2. The MPPT combiner box 5 can send signals to the inverter 2 and also receive signals from the inverter 2.

[0075] Both the first modulation circuit 51 and the second modulation circuit 21 have modulation and demodulation functions for PLC signals. The input / output terminals of the first modulation circuit 51 may include a first input / output terminal P511 and a second input / output terminal P512. The input / output terminals of the second modulation circuit 21 may include a first input / output terminal P211 and a second input / output terminal P212. When the MPPT combiner box 5 sends a signal to the inverter 2, the first modulation circuit 51 modulates the original signal sent by the MPPT combiner box 5 to the inverter 2, and then couples the modulated signal to the power line 04 through the first input / output terminal P511 and the second input / output terminal P512. The second modulation circuit 21 can receive the modulated signal from the power line 04 through the first input / output terminal P211 and the second input / output terminal P212, and then demodulate the received modulated signal to obtain the original signal.

[0076] Similarly, when the inverter 2 sends a signal to the MPPT combiner box 5, the second modulation circuit 21 modulates the original signal sent by the inverter 2 to the MPPT combiner box 5, and couples the modulated signal to the power line 04 through the first input / output terminal P211 and the second input / output terminal P212. The first modulation circuit 51 can receive the modulated signal from the power line 04 through the first input / output terminal P511 and the second input / output terminal P512 to obtain the original signal.

[0077] In one possible implementation, the first power device couples the modulated signal to the power line through electromagnetic coupling, and the second power device receives the modulated signal from the power line through electromagnetic coupling. Specifically, please refer to FIG5 , which shows a schematic diagram of the structure of the power line communication device provided in an embodiment of the present application.

[0078] For example, in the power line communication device shown in Figure 5, the MPPT combiner box 5 transmits DC power to the inverter 2 through the power line 04. The power line 04 includes a positive cable 041 and a negative cable 042, and the positive cable 041 and the negative cable 042 are used to transmit DC power. On the side of the MPPT combiner box 5, the positive cable 041 and the negative cable 042 are connected through a filter capacitor C0. On the side of the inverter 2, the positive cable 041 and the negative cable 042 can also be connected through a filter capacitor C0. Usually, a large current flows through both the positive cable 041 and the negative cable 042. A differential mode noise signal is generated between the positive cable 041 and the negative cable 042. The capacitor C0 is used to filter the differential mode noise signal and enhance the stability of signal transmission.

[0079] The signal line 071 extending from the first input / output terminal P511 of the first modulation circuit 51 passes through the first magnetic ring L1 and is connected to the second input / output terminal P512 of the first modulation circuit 51. That is, the modulation signal of the first modulation circuit 51 is coupled to the first magnetic ring L1. The signal line 072 extending from the first input / output terminal P211 of the second modulation circuit 21 passes through the second magnetic ring L2 and is connected to the second input / output terminal P212 of the second modulation circuit 21. That is, the modulation signal of the second modulation circuit 21 is coupled to the second magnetic ring L2.

[0080] The grounding wire 061 extending from the housing 52 of the MPPT combiner box 5 passes through the first magnetic ring L1 and is connected to the grounding grid 6. That is, the first magnetic ring L1 is coupled to the grounding grid 6. The grounding wire 062 extending from the housing 22 of the inverter 2 passes through the first magnetic ring L2 and is connected to the grounding grid 6. That is, the second magnetic ring L2 is coupled to the grounding grid 6.

[0081] The first magnetic ring L1 and the second magnetic ring L2 can each be coupled to the positive cable 041 via a capacitor. For example, on the MPPT combiner box 5 side, the first magnetic ring L1 is coupled to the positive cable 041 via capacitor C1. On the inverter 2 side, the second magnetic ring L2 is coupled to the positive cable 041 via capacitor C2. In other words, on the MPPT combiner box 5 side, the grounding grid 6 is connected to the positive cable 041 via capacitor C1, while on the inverter 2 side, the grounding grid 6 is connected to the positive cable 041 via capacitor C2.

[0082] In the embodiment shown in Figure 5, a positive cable 041 is used to transmit the modulation signal in conjunction with the ground grid 6. The first modulation circuit 51 is coupled to the ground grid 6 via the first magnetic ring L1. Since the modulation signal is a medium-high frequency signal, typically in the kHz to MHz frequency range, capacitors C1 and C2 can serve as signal transmission channels to transmit the medium-high frequency signal. When the current output by the first modulation circuit is forward, the signal transmission direction is shown by the solid arrow in Figure 5. When the current output by the first modulation circuit 51 is reverse, the signal transmission direction is shown by the dashed arrow in Figure 5. When the current output by the first modulation circuit 51 is forward, the modulation signal coupled to the first magnetic ring L1 is transmitted sequentially through the first magnetic ring L1, capacitor C1, positive cable 041, capacitor C2, and second magnetic ring L2 to the ground grid 6, forming a signal loop between the positive cable 041 and the ground grid 6. On the inverter 2 side, the modulation signal coupled to the positive cable 041 is transmitted to the second magnetic ring L2 via capacitor C2. Inverter 2 can receive the modulation signal from the positive cable 041 via the second magnetic ring L2. When the current output by the first modulation circuit 51 is a reverse current, the modulation signal coupled to the first magnetic ring L1 passes through the second magnetic ring L2 of the ground grid 6, the capacitor C2, the positive cable 041, the capacitor C1 and the first magnetic ring L1 in sequence, forming a signal loop between the positive cable 041 and the ground grid 6. On the side of the inverter 2, the modulation signal coupled to the ground grid 6 is transmitted to the second magnetic ring L2 through the capacitor C2.

[0083] Because both the first and second magnetic rings L1 and L2 are coupled to the ground grid 6, which itself does not transmit electrical energy, the inductance of the first and second magnetic rings L1 and L2 is not drastically reduced due to excessive current transmitted on the power line, thereby improving the stability of the magnetic rings L1 and L2. By forming a modulation signal loop using the ground line O4 (which transmits electrical energy) and the ground grid 6 (which does not transmit electrical energy), signal attenuation is reduced and the reliability of signal transmission is improved.

[0084] Similarly, referring to Figure 6 , the first magnetic ring L1 and the second magnetic ring L2 can each be coupled to the negative cable 042 via capacitors. On the MPPT combiner box 5 side, the first magnetic ring L1 is coupled to the negative cable 042 via capacitor C3, and on the inverter 2 side, the second magnetic ring L2 is coupled to the negative cable 042 via capacitor C4. In other words, on the MPPT combiner box 5 side, the grounding grid 6 is connected to the positive cable 041 via capacitor C1, and on the inverter 2 side, the grounding grid 6 is connected to the positive cable 041 via capacitor C2. A signal loop is formed between the grounding grid 6 and the negative cable 042. The signal transmission method can be referred to the embodiment shown in Figure 5 and will not be further described here.

[0085] Similarly, referring to Figure 7 , the first magnetic ring L1 and the second magnetic ring L2 are both coupled to the positive cable 041 and the negative cable 042 via a capacitor, forming a signal loop between the ground grid 6 and the positive cable 041, and between the ground grid 6 and the negative cable 042. That is, on this side of the MPPT combiner box 5, the first magnetic ring is coupled to the positive cable 041 via capacitor C1, and the first magnetic ring is coupled to the negative cable 042 via capacitor C3. On this side of the inverter 2, the second magnetic ring L2 is coupled to the positive cable 041 via capacitor C2, and the second magnetic ring L2 is coupled to the negative cable 042 via capacitor C4.

[0086] Similarly, referring to Figure 8 , the first magnetic ring L1 and the second magnetic ring L2 can be coupled to the positive cable 041 and the negative cable 042, respectively, via capacitors, forming a signal loop between the ground grid 6, the positive cable 041, and the negative cable 042. Specifically, on the MPPT combiner box 5 side, the first magnetic ring is coupled to the positive cable 041 via capacitor C1. On the inverter 2 side, the second magnetic ring is coupled to the negative cable 042 via capacitor C2. When the MPPT combiner box 5 outputs a modulated signal to the inverter 2, the modulated signal output by the first modulation circuit 51 is coupled to L1. When the current output by the first modulation circuit 51 is positive, the modulated signal coupled to the first magnetic ring L1 is transmitted to the ground grid 6 in sequence through the first magnetic ring L1, capacitor C1, the positive cable 041, capacitor C0 on the MPPT combiner box 5 side, the negative cable 042, capacitor C2, and the second magnetic ring L2. This forms a signal loop between the positive cable 041, the negative cable 042, and the ground grid 6. On the inverter 2 side, the modulated signal coupled to the positive cable 041 is transmitted to the second magnetic ring L2 via the negative cable 042 and capacitor C2. Inverter 2 can receive the modulated signal from the positive cable 041 via the second magnetic ring L2. When the current output by the first modulation circuit 51 is a reverse current, the modulated signal coupled to the first magnetic ring L1 is transmitted to the ground grid 6 via the ground grid 6, the second magnetic ring L2, capacitor C2, capacitor C0 located on the inverter 2 side, the negative cable 042, capacitor C0 located on the MPPT combiner box 5 side, the positive cable 041, capacitor C1, and the first magnetic ring L1. A signal loop is formed between the negative cable 042, the positive cable 041, and the ground grid 6. On the inverter 2 side, inverter 2 can receive the modulated signal from the ground grid 6 via the second magnetic ring L2.

[0087] In one possible implementation, the first power device couples the modulated signal to the power line via capacitive coupling, and the second power device receives the modulated signal from the power line via capacitive coupling. Specifically, please refer to FIG8 , which shows a schematic diagram of the structure of another embodiment of the power line communication device provided in an embodiment of the present application.

[0088] In the power line communication device shown in Figure 9, the MPPT combiner box 5 transmits DC power to the inverter 2 via power line 04. Power line 04 includes a positive cable 041 and a negative cable 042. Positive cable 041 and negative cable 042 are used to transmit DC power. The first input / output terminal P511 of the first modulation circuit 51 is connected to one end of capacitor C5, the other end of which is connected to the ground grid 6. The second input / output terminal P512 of the first modulation circuit 51 is connected to one end of capacitor C7, the other end of which is connected to the positive cable 041. The first input / output terminal P211 of the second modulation circuit 21 is connected to one end of capacitor C6, the other end of which is connected to the ground grid 6. The second input / output terminal P212 of the second modulation circuit 21 is connected to one end of capacitor C8, the other end of which is connected to the positive cable 041. By coupling capacitors C5 and C6 to the ground grid 6, which doesn't transmit electrical energy, the impedance requirements for PLC signals on the power line are reduced, as no large current is generated on the ground grid 6. This reduces the attenuation of the PLC signals, thereby lowering the specification requirements and design difficulty for components such as capacitors, while also improving safety. When the current output by the first modulation circuit 51 is positive, the first input / output terminal P511 of the first modulation circuit 51 transmits a modulation signal to the ground grid 6. The modulation signal is coupled to the ground grid 6 via capacitor C5. The second modulation circuit receives the modulation signal from the ground grid 6 via capacitor C6, demodulates it, and couples the demodulated signal to the positive cable 041 via capacitor C8. The demodulated signal is then transmitted to the first modulation circuit 51 via capacitor C7. A signal loop is formed between the first modulation circuit 51, the ground grid 6, the second modulation circuit 21, and the positive cable 041. When the current output by the first modulation circuit 51 is a reverse current, the second input / output terminal P512 of the first modulation circuit 51 transmits a modulation signal to the positive cable 041 via capacitor C7. The modulation signal is then transmitted to the second modulation circuit 21 via capacitor C8. The second modulation circuit 21 demodulates the modulation signal, transmits the demodulated signal to the ground grid 6 via capacitor C6, and then transmits it to the first modulation circuit 51 via capacitor C5. A signal loop is formed between the first modulation circuit 51, the positive cable 041, the second modulation circuit 21, and the ground grid 6.

[0089] Similarly, a signal loop can also be formed between the ground grid 6 and the negative cable 042. Referring to the schematic structural diagram of an embodiment shown in FIG10 , the first input / output terminal P511 of the first modulation circuit 51 is connected to one end of capacitor C5, the other end of which is connected to the ground grid 6. The second input / output terminal P512 of the first modulation circuit 51 is connected to one end of capacitor C7, the other end of which is connected to the negative cable 042. The first input / output terminal P211 of the second modulation circuit 21 is connected to one end of capacitor C6, the other end of which is connected to the ground grid 6. The second input / output terminal P212 of the second modulation circuit 21 is connected to one end of capacitor C8, the other end of which is connected to the negative cable 042. When the current output by the first modulation circuit 51 is a forward current, a signal loop is formed between the first modulation circuit 51, the ground grid 6, the second modulation circuit 21, and the negative cable 042. When the current output by the first modulation circuit 51 is a reverse current, a signal loop is formed between the first modulation circuit 51, the negative cable 042, the second modulation circuit 21, and the ground grid 6.

[0090] Similarly, the first modulation circuit 51 and the second modulation circuit 21 can be coupled to different power lines via capacitors, as shown in the structural diagram of an embodiment shown in Figure 11. The first input / output terminal P511 of the first modulation circuit 51 is connected to one end of capacitor C5, and the other end of capacitor C5 is connected to the ground grid 6. The second input / output terminal P512 of the first modulation circuit 51 is connected to one end of capacitor C7, and the other end of capacitor C7 is connected to the positive cable 041. The first input / output terminal P211 of the second modulation circuit 21 is connected to one end of capacitor C6, and the other end of capacitor C6 is connected to the ground grid 6. The second input / output terminal P212 of the second modulation circuit 21 is connected to one end of capacitor C8, and the other end of capacitor C8 is connected to the negative cable 042. When the current output by the first modulation circuit 51 is a positive current, a signal loop is formed between the first modulation circuit 51, the ground grid 6, the second modulation circuit 21, the negative cable 042, and the positive cable 041. When the current output by the first modulation circuit 51 is a reverse current, a signal loop is formed among the first modulation circuit 51 , the positive cable 041 , the negative cable 042 , the second modulation circuit 21 and the ground grid 6 .

[0091] In one possible implementation, the MPPT combiner box 5 couples the modulated signal to the power line 04 and the ground grid 6 via electromagnetic coupling, and the inverter 2 receives the modulated signal from the power line 04 and the ground grid 6 via capacitive coupling. In this case, the structure of the power line communication device is shown in Figure 12 . For the specific structure and operating principle of the MPPT combiner box 5 in Figure 12 , refer to the description of the MPPT combiner box 5 shown in Figure 5 . For the specific structure and operating principle of the inverter 2, refer to the description of the inverter 2 shown in Figure 8 , and will not be repeated here.

[0092] In one possible implementation, the MPPT combiner box 5 couples the modulated signal to the power line 04 and the ground grid 6 via capacitive coupling, and the inverter 2 receives the modulated signal from the power line 04 and the ground grid 6 via electromagnetic coupling. In this case, the structure of the power line communication device is shown in FIG13 . For the specific structure and operating principle of the MPPT combiner box 5 side of the power line communication device shown in FIG13 , refer to the description of the MPPT combiner box 5 side of FIG8 . For the specific structure and operating principle of the inverter 2 side of FIG5 , refer to the description of the inverter 2 side of FIG5 , and will not be repeated here.

[0093] In one possible implementation, the modulation circuit is coupled to the power line via a signal coupling device, which is then coupled to the ground grid via a capacitor. As shown in the structural diagram of one embodiment shown in Figure 14 , the first input / output terminal P511 of the first modulation circuit 51 in the MPPT combiner box 5 couples the modulation signal to the ground grid 6 via capacitive coupling, and the second input / output terminal P512 of the first modulation circuit 51 is coupled to the positive cable 041. The signal line leading from the first input / output terminal P211 of the second modulation circuit 21 in the inverter 2 passes through a magnetic ring L and is connected to the second input / output terminal P212 of the second modulation circuit 21. Both the positive cable 041 and the negative cable 042 between the MPPT combiner box 5 and the inverter 2 pass through the magnetic ring L, which increases the impedance of the positive and negative cables 041 and 042, ensuring the stability of PLC signal transmission. Furthermore, since the currents in the positive and negative cables 041 and 042 flow in opposite directions, the magnetic fluxes generated by them cancel each other out. Consequently, the magnetic ring L does not saturate due to excessive current. The magnetic ring L is then coupled to the ground grid 6, which does not transmit electrical energy, via capacitor C2, ensuring that no large current flows through the magnetic ring L, reducing signal attenuation, and improving signal transmission reliability. When the current output by the first modulation circuit 51 is a forward current, the modulation signal transmitted from the first input / output terminal P511 of the first modulation circuit 51 is transmitted to the ground grid 6 via capacitor coupling, and then transmitted to the magnetic ring L via capacitor C2. The second modulation circuit 21 receives the modulation signal coupled by the magnetic ring L, demodulates it, and then transmits it to the magnetic ring L. The demodulated signal can be transmitted to the first modulation circuit 51 via the positive cable 041. When the current output by the first modulation circuit 51 is a reverse current, the modulation signal transmitted from the second input / output terminal P512 of the first modulation circuit 51 is transmitted to the magnetic ring L via the positive cable 041. The second modulation circuit 21 receives the modulation signal coupled by the magnetic ring L, demodulates it, and then transmits it to the magnetic ring L. The demodulated signal can be transmitted to the ground grid via capacitor C2, and then transmitted to the first modulation circuit via capacitor C1. Similarly, when the power line between the first power device and the second power device is used to transmit alternating current, the L-phase cables in the power line can all pass through the magnetic ring to reduce signal attenuation of the magnetic ring.

[0094] Similarly, electromagnetic coupling can be used on the MPPT combiner box 5 side, and capacitive coupling can be used on the inverter 2 side, as shown in the structural diagram of an embodiment in Figure 15. The first modulation circuit 51 is coupled to the ground grid 6 via a magnetic ring L and capacitor C1. Both the positive cable 041 and the negative cable 042 pass through the magnetic ring L. The second modulation circuit 21 is coupled to the ground grid 6 via capacitor C2. The second modulation circuit 21 is coupled to the positive cable 041 via capacitor C3.

[0095] Similarly, electromagnetic coupling is employed on both the MPPT combiner box 5 and the inverter 2, as shown in the structural diagram of an embodiment in FIG16 . The first modulation circuit 51 is coupled to the ground grid 6 via a magnetic ring L1 and a capacitor C1, while the second modulation circuit 21 is coupled to the ground grid 6 via a magnetic ring L2 and a capacitor C2. Both the positive cable 041 and the negative cable 042 pass through the magnetic rings L1 and L2.

[0096] When the power line communication device 100 is located between the data collector 4 and the inverter 2, the inverter 2 transmits AC power to the data collector 4 via the power line 05. Figure 17 shows a schematic diagram of the structure of the power line communication device 100 located between the data collector 4 and the inverter 2. Because the input / output current of the data collector 4 is relatively low, while the input / output current of the inverter 2 is relatively high, the data collector 4 typically receives the AC power and PLC signals transmitted by the inverter 2 through the power distribution cabinet 7. The power line 05 includes L-phase cables 051, 052, and 053. Filter capacitors are installed between each pair of L-phase cables 051, 052, and 053 to filter differential mode noise signals and enhance signal transmission stability. In this embodiment, the data collector 4 couples the modulated signal to the power line 05 via capacitive coupling, and the inverter 2 receives the modulated signal from the power line via electromagnetic coupling. The first modulation circuit 41 is provided in the data collector 4, and the second modulation circuit 21 is provided in the inverter 2. The first input / output terminal P411 of the first modulation circuit 41 is connected to one end of capacitor C1, the other end of which is connected to the ground grid 6. The second input / output terminal P412 of the first modulation circuit 41 is connected to one end of capacitor C2, the other end of which is connected to cable 051. A signal line extending from the first input / output terminal P211 of the second modulation circuit 21 passes through the second magnetic ring L2 and is connected to the second input / output terminal P212 of the second modulation circuit 21. This means that the modulation signal of the second modulation circuit 21 is coupled to the second magnetic ring L2, which is then coupled to cable 051 via capacitor C3. When the first modulation circuit 41 outputs a forward current, the modulation signal output by the first modulation circuit 41 is transmitted to the L-phase cable 051 via capacitor C2, and then coupled to magnetic ring L2 via capacitor C3. The second modulation circuit receives the modulation signal from magnetic ring L2, demodulates it, and transmits it to magnetic ring L2. Magnetic ring L2 then transmits the demodulated signal to the ground grid 6. When the first modulation circuit 41 outputs a reverse current, the modulation signal output by the first modulation circuit 41 is transmitted to the grounding grid 6 through the capacitor C1, and then coupled to the magnetic ring L2. The second modulation circuit receives the modulation signal of the magnetic ring L2, demodulates it, and transmits it to the magnetic ring L2. The magnetic ring L2 then transmits the demodulated signal to the L-phase cable 051 through the capacitor C3, and then transmits it to the first modulation circuit 51 through the capacitor C2.

[0097] Based on the same inventive concept, the present application also provides an electric power device 200, the structure of which is shown in FIG18 . The electric power device 200 includes a modulation circuit 201, a magnetic ring L, and power lines 041 and 042. The electric power device 200 receives electric energy transmitted from other electric power devices 300 via power lines 041 and 042. The modulation circuit 201 is coupled to the ground grid 6 via the magnetic ring. The modulation circuit 201 receives PLC signals transmitted from other electric power devices 300 via power lines 041 and 042 and the ground grid 6 via the magnetic ring. The magnetic ring L is coupled to the positive cable 041 via a capacitor C1. When the modulation circuit outputs a positive current, the modulation signal output by the modulation circuit is coupled to the magnetic ring L, transmitted to the positive cable 041 via the capacitor C1, and then transmitted to the other electric power device 300 via the positive cable 041. The other electric power device 300 demodulates the modulation signal and transmits it to the ground grid. The signal is then transmitted to the magnetic ring L via the ground grid 6, forming a signal loop. When the modulation circuit outputs reverse current, the modulation signal output by the modulation circuit is coupled to the magnetic ring L, and then transmitted to other power equipment 300 through the grounding grid 6. After demodulating the modulation signal, the other power equipment 300 transmits it to the positive cable 041, and then transmits it to the magnetic ring L through the capacitor C1.

[0098] The power equipment 200 may be the power equipment such as the photovoltaic component 1 , the inverter 2 , the transformer 3 and the data collector 4 in the photovoltaic system 100 described above.

[0099] It should be understood that the magnetic ring L and capacitor mentioned above can also be replaced by an inductor.

[0100] Based on the same inventive concept, an embodiment of the present application further provides a photovoltaic system comprising a plurality of power devices, wherein a power line communication device as described above is provided between each pair of the power devices, wherein medium and high frequency signals between each pair of power devices are transmitted via the power line provided between the two devices. For a schematic structural diagram of the photovoltaic system, reference may be made to Figures 1-3.

[0101] Figure 19 shows a schematic diagram of a power line communication device located between an inverter 2 and two MPPT combiner boxes 5. The MPPT combiner boxes 501 and 502 are connected in parallel. The positive cable 0411 extending from the MPPT combiner box 501 is connected to the positive cable 0413 extending from the MPPT combiner box 502, and the negative cable 0412 extending from the MPPT combiner box 501 is connected to the negative cable 0414 extending from the MPPT combiner box 502. The second modulation circuit 21 located in the inverter 2 is coupled to the ground grid 61 and the ground grid 62 via the first magnetic ring L1. The first magnetic ring L1 is coupled to the positive cable 0413 via the capacitor C1. The first modulation circuit 5101 located in the MPPT combiner box 501 couples the modulation signal output by the first modulation circuit 5101 to the ground grid 61 and the negative cable 0412 via the third magnetic ring L3 and the third capacitor C3, respectively. The first modulation circuit 5102 in the MPPT combiner box 502 couples the modulation signal output by the first modulation circuit 5102 to the ground grid 62 and the positive cable 0413 through the third magnetic ring L2 and the third capacitor C2 respectively.

[0102] Figure 20 shows a schematic diagram of a power line communication device located between a data collector 4 and two inverters 2. Inverters 201 and 202 are connected in parallel. Three L-phase cables 0411, 0412, and 0413 extending from inverter 201 are connected to three L-phase cables 0416, 0414, and 0415 extending from inverter 202, respectively. A first modulation circuit 41 within data collector 4 is coupled to ground grids 61 and 62 via capacitor C4. A second modulation circuit 2101 within inverter 201 couples the modulated signal output by the second modulation circuit 2101 to ground grid 61 and L-phase cable 0413 via a third magnetic ring L3 and capacitor C3, respectively. A first modulation circuit 2102 within inverter 202 is coupled to ground grid 62 and L-phase cable 0414, respectively, via a second magnetic ring L2 and capacitor C2.

[0103] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. An inverter, characterized in that: The inverter includes a modulation circuit, a signal coupling device and a power line. The power equipment receives electric energy transmitted by other power equipment through the power line. The modulation circuit is coupled to a grounding grid through the signal coupling device. The modulation circuit receives a PLC signal transmitted by the other power equipment through the power line and the grounding grid through the signal coupling device. The signal coupling device is any one of a magnetic ring, an inductor and a capacitor.

2. The inverter according to claim 1, characterized in that: The input / output terminal of the modulation circuit is coupled to the signal coupling device; The modulation circuit transmits the PLC signal to the power line and the ground grid through the signal coupling device.

3. The inverter according to claim 1 or 2, characterized in that: The signal coupling device is a magnetic ring, the first input / output end of the modulation circuit passes through the magnetic ring to be connected to the second input / output end of the modulation circuit, and the ground wire of the inverter passes through the magnetic ring.

4. The inverter according to claim 3, characterized in that: The signal coupling device is coupled to the power line via capacitance.

5. The inverter according to claim 4, characterized in that: The power line is used to transmit direct current power, and the signal coupling device is coupled to at least one of the positive cable or the negative cable in the power line through the capacitor.

6. The inverter according to claim 4, characterized in that: The power line is used to transmit alternating current power, and the signal coupling device is coupled to at least one of the L-phase cable or the N-phase cable in the power line through the capacitor.

7. The inverter according to claim 1 or 2, characterized in that: The signal coupling device is an inductor, the first input / output terminal of the modulation circuit is connected to one end of the inductor, and the other end of the inductor is connected to the ground grid.

8. The inverter according to claim 1 or 2, characterized in that: The signal coupling device includes a first capacitor and a second capacitor. The first input / output terminal of the modulation circuit is connected to one end of the first capacitor, and the other end of the first capacitor is connected to the ground grid.

9. The inverter according to claim 8, characterized in that: The second input / output terminal of the modulation circuit is coupled to the power line through a second capacitor.

10. A photovoltaic system, characterized in that: The photovoltaic system comprises the inverter according to any one of claims 1 to 9 and other power equipment, and the inverter is used to receive the PLC signal transmitted by the other power equipment.

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