Photovoltaic system

Abstract

The utility model is suitable for the field of photovoltaic technology, and provides a photovoltaic system which comprises an inverter and at least two combiner boxes. The inverter comprises a direct current bus, a carrier chip, at least two signal amplification circuits, at least two isolation transformers and at least two host magnets, the output end of the carrier chip is connected with the input end of each signal amplification circuit, and the output end of each signal amplification circuit is connected with the primary winding of each isolation transformer. A secondary winding of each isolation transformer is connected with each host magnet; the host magnet is arranged on the inverter side direct current input cable; the combiner box comprises a power line carrier communication slave circuit and a slave magnet, the power line carrier communication slave circuit is connected with the slave magnet, and the slave magnet is arranged on an output cable of the combiner box; a positive output cable of the combiner box is connected to the positive DC bus, and a negative output cable of the combiner box is connected to the negative DC bus. According to the technical scheme of the utility model, the communication cost of the inverter and the combiner box can be reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of photovoltaic, and particularly relates to a photovoltaic system. Background Art

[0002] In the prior art, there are mainly the following two ways for communication between an inverter and a busbar box:

[0003] First, use the RS485 communication method for communication. However, this method requires laying RS485 communication lines, which is difficult in wiring, has a high maintenance cost, and the RS485 communication method also has problems of short communication distance and low communication efficiency.

[0004] Second, use the wireless communication method for communication. However, this method has problems of unstable signal transmission and small signal coverage. Summary of the Utility Model

[0005] The utility model provides a photovoltaic system, aiming to solve the problem of high communication cost between an inverter and a busbar box.

[0006] The utility model is implemented as follows. A photovoltaic system includes an inverter and at least two busbar boxes;

[0007] The inverter includes a DC bus, a carrier chip, at least two signal amplification circuits, at least two isolation transformers, and at least two host magnets. The output end of the carrier chip is connected to the input ends of the respective signal amplification circuits. The output ends of the respective signal amplification circuits are connected to the primary windings of the respective isolation transformers in a one-to-one correspondence. The secondary windings of the respective isolation transformers are connected to the coupling wires of the respective host magnets in a one-to-one correspondence. Each of the host magnets is disposed on the DC input cable on the inverter side;

[0008] Each busbar box includes a power line carrier communication slave circuit and a slave magnet. The power line carrier communication slave circuit is connected to the slave magnet, and the slave magnet is disposed on the output cable of the corresponding busbar box;

[0009] The positive output cable of the busbar box is connected to the positive DC bus, and the negative output cable of the busbar box is connected to the negative DC bus.

[0010] Furthermore, the inverter further includes a filtering circuit. The input end of the filtering circuit is connected to the primary windings of the respective isolation transformers, and the output end of the filtering circuit is connected to the input end of the carrier chip.

[0011] Furthermore, the host magnet is a magnetic ring, and each host magnetic ring is sleeved on the DC input cable on the inverter side.

[0012] Furthermore, the carrier chip is a power line carrier communication chip.

[0013] Furthermore, the slave magnet is a magnetic ring.

[0014] Furthermore, each slave magnetic ring is sleeved on the positive output cable of the bus duct.

[0015] Furthermore, each slave magnetic ring is sleeved on the negative output cable of the bus duct.

[0016] Furthermore, the photovoltaic system further includes a filter capacitor;

[0017] The filter capacitor is connected between the positive DC bus and the negative DC bus.

[0018] In the technical solution of the present utility model, the carrier signal of the carrier chip in the inverter can be amplified by the signal amplification circuit, then transmitted through the isolation transformer, and then coupled and transmitted to the bus duct through the host magnet. The power line carrier communication slave circuit in the bus duct can couple the carrier signal through the slave magnet to realize the communication between the inverter and the bus duct. Since there is no need to lay RS485 communication lines for the interaction of signals between the inverter and each bus duct, the construction cost and maintenance cost of the communication between the inverter and the bus duct can be reduced. And the communication distance and stability between the inverter and the bus duct can be increased by increasing the intensity of the carrier signal. With such a setting, compared with the wireless communication method, the signal transmission is more stable and the reliability is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the network structure block diagram of the photovoltaic system in an embodiment;

[0020] Figure 2 is the circuit structure block diagram of an embodiment of the photovoltaic system of the present utility model;

[0021] Figure 3 is the circuit structure block diagram of another embodiment of the photovoltaic system of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] In order to make the objectives, technical solutions and advantages of the present utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0023] In this embodiment, the carrier signal of the carrier chip in the inverter can be amplified by a signal amplification circuit, and then transmitted to the busbar box through an isolation transformer and a host magnet. The power line carrier communication slave circuit in the busbar box can couple the carrier signal through the slave magnet to realize communication between the inverter and the busbar box. With this setting, it is not necessary to lay RS485 communication lines for signal interaction between the inverter and each busbar box, reducing the construction cost and maintenance cost of communication between the inverter and each busbar box. Moreover, by increasing the intensity of the carrier signal, the communication distance and stability between the inverter and the busbar box can be increased. With this setting, compared with the wireless communication method, the signal transmission is more stable and the reliability is higher.

[0024] Referring to Figure 1 , in practical applications, the networking structure of a photovoltaic system often includes a single inverter, at least one busbar box, and at least one photovoltaic array panel. Among them, one end of the busbar box is connected to the corresponding photovoltaic array panel, and the other end is connected to the inverter. If the RS485 communication method is used to realize communication between the inverter and the busbar box, there will be problems such as difficult wiring and high maintenance costs. Moreover, the RS485 communication method also has problems such as short communication distance and low communication efficiency. In order to reduce the communication cost between the busbar box and the inverter, the inverter and the busbar box provided in this embodiment use power line carrier communication, that is, use a DC cable for carrier communication without specifically laying RS485 communication lines, so as to achieve the purpose of reducing the communication cost between the inverter and the busbar box.

[0025] Example 1

[0026] Referring to Figure 2 , the present utility model provides a photovoltaic system, which includes an inverter, a DC busbar, and at least two busbar boxes.

[0027] The inverter includes a DC busbar, a carrier chip 10, at least two signal amplification circuits 20 to 2n, at least two isolation transformers 30 to 3n, and at least two host magnets 40 to 4n. Among them, the output end of the carrier chip 10 is connected to the input ends of the respective signal amplification circuits 20 to 2n, the output ends of the respective signal amplification circuits 20 to 2n are connected to the primary windings of the respective isolation transformers 30 to 3n in a one-to-one correspondence, and the secondary windings of the respective isolation transformers 30 to 3n are connected to the coupling lines of the respective host magnets in a one-to-one correspondence; and each host magnet 40 to 4n is disposed on the DC input cable on the inverter side, that is, the host magnetic ring can be sleeved at the connection between the DC output cable of the busbar box and the DC input cable of the inverter to couple the carrier signal; the host magnet 40 to 4n can be a magnetic ring, and each host magnetic ring is sleeved on the DC input cable on the inverter side, and the positive and negative are not limited and can be set according to actual needs.

[0028] Each combiner box includes a power line carrier communication slave circuit and a slave magnet. The power line carrier communication slave circuit is connected to the slave magnet, and each slave magnet is disposed on the output cable of its corresponding combiner box. Among them, the slave magnet can be a magnetic ring, and the slave magnetic ring can be sleeved on the positive output cable of its corresponding combiner box or on the negative output cable of its corresponding combiner box. The positive output cable of the combiner box is connected to the positive DC bus, and the negative output cable of the combiner box is connected to the negative DC bus.

[0029] Further, in order to make the system communication more stable and reliable, the volume of a single host magnet can be set to be the same as the volume of a single slave magnet.

[0030] In this embodiment, the power line carrier communication slave circuit uses the power cable in the photovoltaic power station as the physical medium and utilizes modulation and demodulation technologies to complete the communication between devices. Its advantage is that no separate communication cable needs to be laid.

[0031] In this embodiment, the signal amplification circuits 20 to 2n can be PAs (power amplifiers). Each signal amplification circuit is arranged in parallel, which can enhance the intensity of the carrier signal and can support broadcasting in terms of electrical connection.

[0032] In this embodiment, the carrier signal of the carrier chip 10 in the inverter can be subjected to signal amplification processing by the signal amplification circuit, then transmitted through the isolation transformer, and then coupled and transmitted to the combiner box through the host magnet; during the process, the power line carrier communication slave circuit of the combiner box can couple the carrier signal through the slave magnet to realize the communication transmission between the inverter and the combiner box. Among them, each host magnet can couple the carrier signal with the DC bus, and each host magnet can also interact with the carrier chip 10 through the corresponding isolation transformer and signal amplification circuit; while the power line carrier communication slave circuit can couple the carrier signal through the slave magnet to realize the communication between the inverter and the combiner box. With such a setting, it is not necessary to lay RS485 communication lines for the inverter to interact with each combiner box, reducing the construction cost and maintenance cost of communication. And the communication distance and stability between the inverter and the combiner box can be increased by increasing the intensity of the carrier signal. With such a setting, compared with the wireless communication method, the signal transmission is more stable and the reliability is higher.

[0033] Example 2

[0034] Refer to Figure 2 and Figure 3 In an embodiment, the photovoltaic system further includes a filter circuit 50. The input end of the filter circuit 50 is connected to the primary windings of the isolation transformers 30 to 3n, and the output end of the filter circuit 50 is connected to the input end of the carrier chip 10.

[0035] The filter circuit 50 may be a bandpass filter or other circuit structures, which are not limited here. The filter circuit 50 is used to filter the carrier signal output by the combiner box so that the carrier signal of a specific frequency band is smoothly transmitted to the carrier chip 10 in the inverter, thereby ensuring the bidirectional transmission of the signal between the inverter and the combiner box. In one embodiment, the photovoltaic system further includes a filter capacitor C1; the filter capacitor C1 is connected between the positive DC bus and the negative DC bus.

[0036] In this embodiment, the power line carrier communication slave circuit transmits the carrier signal to the inverter through slave magnet coupling; and transmits the carrier signal to the carrier chip 10 through the host magnet, isolation transformer and filter circuit 50 in the inverter, so as to realize the two-way transmission of the signal between the inverter and the combiner box. Such a setting makes it unnecessary to lay RS485 communication lines for the signal interaction between the inverter and the combiner box, the initial construction cost is low, and the later maintenance is simple, which greatly reduces the communication cost between the inverter and the combiner box, and compared with the wireless communication method, the signal transmission is more stable and the reliability is higher.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A photovoltaic system, characterized in that: The photovoltaic system includes an inverter and at least two combiner boxes; The inverter includes a DC bus, a carrier chip, at least two signal amplification circuits, at least two isolation transformers and at least two host magnets. The output end of the carrier chip is connected to the input end of each of the signal amplification circuits. The output end of each of the signal amplification circuits is connected to the primary winding of each of the isolation transformers in a one-to-one correspondence. The secondary winding of each of the isolation transformers is connected to the coupling line of each of the host magnets in a one-to-one correspondence. Each of the host magnets is arranged on the DC input cable on the inverter side. Each of the combiner boxes comprises a power line carrier communication slave circuit and a slave magnet, wherein the power line carrier communication slave circuit is connected to the slave magnet, and the slave magnet is arranged on an output cable of the corresponding combiner box; The positive output cable of the combiner box is connected to the positive DC bus, and the negative output cable of the combiner box is connected to the negative DC bus.

2. The photovoltaic system according to claim 1, characterized in that: The inverter further includes a filter circuit, an input end of the filter circuit is connected to the primary winding of each of the isolation transformers, and an output end of the filter circuit is connected to an input end of the carrier chip.

3. The photovoltaic system according to claim 2, characterized in that: The host magnet is a magnetic ring, and each host magnetic ring is sleeved on the inverter-side DC input cable.

4. The photovoltaic system according to claim 1, characterized in that: The carrier chip is a power line carrier communication chip.

5. The photovoltaic system according to claim 2, characterized in that: The slave magnet is a magnetic ring.

6. The photovoltaic system according to claim 5, characterized in that: Each slave magnetic ring is sleeved on the positive output cable of the combiner box.

7. The photovoltaic system according to claim 5, characterized in that: Each slave magnetic ring is sleeved on the negative output cable of the combiner box.

8. The photovoltaic system according to any one of claims 1 to 7, characterized in that: The photovoltaic system also includes a filter capacitor; The filter capacitor is connected between the positive DC bus and the negative DC bus.

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