CN204652311U - A kind of photovoltaic combiner box and photovoltaic system - Google Patents

Abstract

The present application discloses a photovoltaic combiner box and a photovoltaic system. The photovoltaic combiner box includes a box body and a confluence circuit arranged in the box. The confluence circuit is used to combine N strings of the photovoltaic array into a positive Output, N>1, the bus circuit includes 2N DC switches and N DC/DC circuits, wherein: after the positive and negative poles of each string are connected in series with one of the DC switches, one of the DC switches is connected. The positive and negative input terminals of the DC/DC circuit; the positive and negative output terminals of the N DC/DC circuits are connected in parallel and then connected to the DC bus, which solves the problem that the photovoltaic combiner box needs to replace the fuse frequently, and the photovoltaic combiner box or its The photovoltaic system maintenance work is time-consuming and labor-intensive.

Description

A photovoltaic combiner box and photovoltaic system

technical field

The utility model relates to the technical field of photovoltaic power generation, in particular to a photovoltaic combiner box and a photovoltaic system.

Background technique

A photovoltaic combiner box is a device used to combine multiple strings of a photovoltaic array into one positive and negative output. For the sake of safety, the existing photovoltaic combiner box connects fuses in series on the positive and negative poles of each string to provide reverse overcurrent protection. As shown in Figure 1, the A total of 2N fuses are connected in series on the positive and negative poles (use FU to represent the fuse). However, this scheme has the following disadvantages:

1) The fuse is blown by reverse overcurrent, and the damage rate is high, so it needs to be replaced frequently;

2) When maintaining the photovoltaic combiner box or the photovoltaic system where it is located, it is necessary to unplug each fuse to disconnect all string inputs, and then install them back one by one, which is time-consuming and laborious.

Utility model content

In view of this, the utility model provides a photovoltaic combiner box and a photovoltaic system to solve the problem that the photovoltaic combiner box requires frequent replacement of fuses, and the maintenance of the photovoltaic combiner box or the photovoltaic system where it is located is time-consuming and laborious.

A photovoltaic combiner box, comprising a box body and a busbar circuit arranged in the box body, the busbar circuit is used to gather N strings of a photovoltaic array into one positive and negative output, N>1, and the busbar circuit includes 2N DC switches and N DC/DC circuits, of which:

After the positive and negative poles of each of the strings are connected in series with one of the DC switches, they are connected to the positive and negative input ends of one of the DC/DC circuits;

The positive and negative output terminals of the N DC/DC circuits are connected in parallel and then connected to the DC bus.

Optionally, the bus circuit further includes a disconnect switch, wherein the positive and negative output terminals of the N DC/DC circuits are connected in parallel and then connected to the DC bus through the disconnect switch.

Wherein, the plurality of DC/DC circuits are Boost circuits or flyback circuits.

Wherein, the 2N DC switches are all manual switches.

Wherein, the 2N DC switches are electronically controlled switches.

Optionally, the photovoltaic combiner box further includes: a controller disposed in the box and connected to the 2N DC switches and the N DC/DC circuits.

Wherein, the controller has an external communication interface.

Wherein, the external communication interface is a wired communication interface or a wireless communication interface.

Optionally, the photovoltaic combiner box further includes: a local operation unit arranged in the box and connected to the controller.

A photovoltaic system, including any photovoltaic combiner box mentioned above.

It can be seen from the above technical scheme that the utility model uses a DC switch instead of a fuse, and cuts off the connection between all strings and the bus circuit by disconnecting each DC switch when it is necessary to maintain the photovoltaic combiner box and the photovoltaic system where it is located. When it is necessary to resume work, each DC switch is directly closed to connect all the electrical connections between the strings and the bus circuit. During this period, the process of repeatedly unplugging and reinstalling the DC switch is not involved, which facilitates the photovoltaic system. maintain. Moreover, the utility model uses a DC/DC circuit as an anti-backflow device, and there will be no reverse overcurrent phenomenon, so there is no need to use a fuse to achieve reverse overcurrent protection, which solves the problem that the photovoltaic combiner box needs to frequently replace the fuse. In addition, the DC/DC circuit can also realize the power optimization of the photovoltaic array by performing maximum power point tracking on the photovoltaic energy.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are only some embodiments of the utility model, and those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a structural schematic diagram of a photovoltaic combiner box disclosed in the prior art;

Fig. 2 is a schematic structural diagram of a photovoltaic combiner box disclosed in an embodiment of the present invention;

Fig. 3 is a structural schematic diagram of another photovoltaic combiner box disclosed in the embodiment of the present invention;

Fig. 4 is a structural schematic diagram of another photovoltaic combiner box disclosed in the embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. example. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

Referring to Fig. 2, the embodiment of the utility model discloses a photovoltaic combiner box to solve the problem that the photovoltaic combiner box needs to replace the fuse frequently, and the maintenance of the photovoltaic combiner box or the photovoltaic system where it is located is time-consuming and laborious. It includes a box body and A confluence circuit arranged in the box; the confluence circuit is used to integrate the N strings of the photovoltaic array into one positive and negative output, and its components include at least 2N DC switches (use S to represent DC switches) and N DC/DC circuits, where:

After the positive and negative poles of each of the strings are connected in series with one of the DC switches, they are connected to the positive and negative input ends of one of the DC/DC circuits;

The positive and negative output ends of the N DC/DC circuits are connected in parallel and then connected to the DC bus (BUS is used to represent the DC bus).

The DC switch can manually or automatically break or connect the DC circuit according to the control signal and requirements imposed by the outside world. Based on this, in this embodiment, a DC switch is used instead of a fuse, and when the photovoltaic combiner box or the photovoltaic system where it is located needs to be maintained, each DC switch is disconnected to cut off the electrical connection between all strings and the bus circuit. When it is necessary to restore the photovoltaic combiner box or the photovoltaic system where it is located, each DC switch is directly closed to connect all the electrical connections between the strings and the bus circuit. Compared with the fuse, the process of using the DC switch to disconnect or connect the string input does not involve the process of repeatedly unplugging and reinstalling the DC switch, so it is convenient for the maintenance of the photovoltaic combiner box or the photovoltaic system where it is located.

In this embodiment, the 2N DC switches may be manual switches, such as knife switches, or electronically controlled switches, such as relays and electric operation switches.

The DC/DC circuit is a unidirectional circuit, which can prevent the current from flowing into the photovoltaic side from the DC bus side in reverse, and there will be no reverse overcurrent phenomenon, so there is no need to use a fuse to provide reverse overcurrent protection. In addition, the DC/DC circuit can also realize the power optimization of the photovoltaic array by tracking the maximum power point of the photovoltaic energy, so that the photovoltaic combiner box is no longer just a confluence function for each string, but also a power optimization effect.

In this embodiment, the N DC/DC circuits may use a Boost circuit or a flyback circuit, which is not limited thereto.

In addition, referring to FIG. 3 , based on the above-mentioned embodiments, the utility model discloses yet another photovoltaic combiner box. The combiner circuit in the photovoltaic combiner box further includes: a circuit breaker, wherein the positive and negative terminals of the N DC/DC circuits The output terminals are connected in parallel and then connected to the DC bus through the circuit breaker. The disconnect switch is used to disconnect the electrical connection between the bus circuit and the subsequent circuit when the photovoltaic combiner box or the photovoltaic system where it is located needs to be maintained.

In addition, in the case that the 2N DC switches are all electronically controlled switches, based on any of the above-mentioned embodiments, the utility model discloses another photovoltaic combiner box, as shown in Fig. 4 , the photovoltaic combiner box further includes: A controller in the box of the photovoltaic combiner box, the controller is connected to the 2N DC switches and the N DC/DC circuits, and is used to judge the failure of the photovoltaic system and control the operation of the N DC/DC circuits And controlling the on-off of the 2N DC switches, etc.

Optionally, the controller also has an external communication interface for sending the operating status of the photovoltaic combiner box to the outside or accepting external control instructions. The communication interface may be a wired communication interface or a wireless communication interface.

Optionally, the photovoltaic combiner box also has a local operating unit disposed in the box and connected to the controller. The local operation unit may include an input device and an output device, wherein: the output device is used to display the current state of the bus circuit, such as the on-off state of the 2N DC switches, the operation of the N DC/DC circuits Stop state, electrical parameter information of N strings, etc., as a typical implementation, the output device can be an indicator light, a digital tube or a liquid crystal screen, etc.; the input device is used to input and control the N DC/DC Commands for circuit operation, commands for controlling the on-off of the 2N DC switches, etc., as a typical implementation manner, the input device may be an operating keyboard. Alternatively, the local operation unit may also adopt a touch screen integrating input and output functions.

To sum up, the utility model replaces the fuse with a DC switch, and cuts off the electrical connection between all strings and the bus circuit by disconnecting each DC switch when it is necessary to maintain the photovoltaic combiner box and the photovoltaic system where it is located. When it is necessary to resume work, each DC switch is directly closed to connect all the electrical connections between the strings and the bus circuit. During this period, the process of repeatedly unplugging and reinstalling the DC switch is not involved, which facilitates the maintenance of the photovoltaic system. Moreover, the utility model uses a DC/DC circuit as an anti-backflow device, and there will be no reverse overcurrent phenomenon, so there is no need to use a fuse to achieve reverse overcurrent protection, which solves the problem that the photovoltaic combiner box needs to frequently replace the fuse. In addition, the DC/DC circuit can also realize the power optimization of the photovoltaic array by performing maximum power point tracking on the photovoltaic energy.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other.

The above description of the disclosed embodiments enables those skilled in the art to realize or use the utility model. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A photovoltaic combiner box, comprising a box body and a busbar circuit arranged in the box body, the busbar circuit is used to gather N strings of the photovoltaic array into one positive and negative output, N>1, characterized in that , the bus circuit includes 2N DC switches and N DC/DC circuits, wherein: After the positive and negative poles of each of the strings are connected in series with one of the DC switches, they are connected to the positive and negative input ends of one of the DC/DC circuits; The positive and negative output terminals of the N DC/DC circuits are connected in parallel and then connected to the DC bus. 2. The photovoltaic combiner box according to claim 1, wherein the combiner circuit further includes a circuit breaker, wherein the positive and negative output terminals of the N DC/DC circuits are connected in parallel and then passed through the circuit breaker. The switch is connected to the DC bus. 3. The photovoltaic combiner box according to claim 1 or 2, wherein the multiple DC/DC circuits are Boost circuits or flyback circuits. 4. The photovoltaic combiner box according to claim 1 or 2, wherein the 2N DC switches are all manual switches. 5. The photovoltaic combiner box according to claim 1 or 2, wherein the 2N DC switches are all electronically controlled switches. 6. The photovoltaic combiner box according to claim 5, characterized in that, the photovoltaic combiner box further comprises: arranged in the box and connected to the 2N DC switches and the N DC/DC circuits controller. 7. The photovoltaic combiner box according to claim 6, wherein the controller has an external communication interface. 8. The photovoltaic combiner box according to claim 7, wherein the external communication interface is a wired communication interface or a wireless communication interface. 9. The photovoltaic combiner box according to claim 6, characterized in that, the photovoltaic combiner box further comprises: a local operation unit arranged in the box and connected to the controller. 10. A photovoltaic system, characterized by comprising the photovoltaic combiner box according to any one of claims 1-9.