CN220605544U - Photovoltaic power generation system, photovoltaic inverter and direct current combiner box - Google Patents

Abstract

The utility model discloses a photovoltaic power generation system, a photovoltaic inverter and a direct current combiner box. The photovoltaic power generation system comprises a DC-DC converter used for being connected with a photovoltaic module; the photovoltaic module comprises a first photovoltaic unit group, wherein the first photovoltaic unit group comprises M photovoltaic units connected in parallel, and each photovoltaic unit comprises a positive output port connected to a positive direct current bus and a negative output port connected to a negative direct current bus; the number of the protection switch modules is greater than or equal to M, at least one protection switch module is connected in series between positive output ports of every two adjacent photovoltaic units, and/or at least one protection switch module is connected in series between negative output ports of every two adjacent photovoltaic units. The photovoltaic power generation system, the photovoltaic inverter and the direct current combiner box realize multiple protection during faults.

Description

Photovoltaic power generation system, photovoltaic inverter and direct current combiner box

Technical Field

The utility model belongs to the technical field of photovoltaic power generation, and particularly relates to a photovoltaic power generation system, a photovoltaic inverter and a direct current combiner box.

Background

Photovoltaic power generation is a technique that uses the photovoltaic effect of a semiconductor interface to convert light energy into electrical energy. Photovoltaic power generation systems typically include photovoltaic units, inverters, ac power distribution equipment, and the like. In order to obtain a higher output voltage or output current, the photovoltaic unit is generally formed by a plurality of photovoltaic modules in a certain series-parallel connection manner. In order to increase the Power generation efficiency of the photovoltaic Power generation system, the photovoltaic unit may be connected to a device having an independent Maximum Power point tracking (Maximum Power PointTracking, MPPT) function to increase the Power generation efficiency of the photovoltaic Power generation system.

At present, in order to improve the direct current ratio (the ratio of the power of a photovoltaic unit to the input power of a photovoltaic inverter) of a photovoltaic power generation system, at least two paths of photovoltaic units are usually connected to each MPPT device, however, when one path of photovoltaic unit has faults such as short circuit or reverse connection, the short circuit current of the path is the sum of the output currents of the connected photovoltaic units of other paths, and when the number of the connected photovoltaic units of other paths is large, the one path of photovoltaic unit is easily burnt out due to overlarge current.

The existing partial photovoltaic system is connected with a fuse in series at the positive output end or the negative output end of the photovoltaic unit, so that the photovoltaic unit and a circuit are protected by fusing the fuse, however, the fusing current of the fuse is generally higher, so that the fuse consumes a long time, the failure rate of the fuse is relatively higher, and the reliability is low. The other part of photovoltaic system adds a protection switch on the branch of each path of photovoltaic unit, however, the pole number close to the handle side of a common direct current switch is easy to trip in the tripping process, and the problem of poor tripping easily occurs in the pole number far away from the handle side.

Disclosure of Invention

Aiming at the technical problems, the utility model provides an improved photovoltaic power generation system, a photovoltaic inverter and a direct current combiner box.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

a photovoltaic power generation system includes a DC-DC converter for switching in a photovoltaic module;

the photovoltaic module comprises at least one photovoltaic unit group, wherein the photovoltaic unit group comprises a photovoltaic unit, and the photovoltaic unit comprises at least one photovoltaic assembly;

the DC-DC converter comprises a plurality of protection switch modules, a direct current bus and a DC-DC circuit;

the direct current bus is connected with the input end of the DC-DC circuit, and the output end of the DC-DC circuit is the output end of the DC-DC converter; the direct current bus comprises a positive direct current bus and a negative direct current bus;

the protection switch module is used for controlling the circuit to be disconnected when the reverse current of the circuit is larger than a first current value or the circuit is over-current;

the photovoltaic unit group comprises a first photovoltaic unit group, wherein the first photovoltaic unit group comprises M photovoltaic units which are connected in parallel, M is a positive integer greater than or equal to 2, and each photovoltaic unit comprises a positive output port connected to the positive direct current bus and a negative output port connected to the negative direct current bus; the number of the protection switch modules is greater than or equal to M, at least one protection switch module is connected in series between the positive output ports of every two adjacent photovoltaic units, and/or at least one protection switch module is connected in series between the negative output ports of every two adjacent photovoltaic units.

Preferably, in the first photovoltaic unit group, one protection switch module is connected in series between the positive output ports of every two adjacent photovoltaic units, and the protection switch module is not arranged between the negative output port of the photovoltaic unit and the negative direct current bus;

or, in the first photovoltaic unit group, one protection switch module is connected in series between the positive output ports of two adjacent photovoltaic units, and one protection switch module is connected in series between the negative output port of each photovoltaic unit and the negative direct current bus;

or, in the first photovoltaic unit group, one protection switch module is connected in series between the positive output ports of two adjacent photovoltaic units, and the same protection switch module is connected in series between the negative output port and the negative direct current bus of each photovoltaic unit.

Preferably, in the first photovoltaic unit group, one protection switch module is connected in series between the negative output ports of every two adjacent photovoltaic units, and the protection switch module is not arranged between the positive output port of the photovoltaic unit and the positive direct current bus;

or, in the first photovoltaic unit group, one protection switch module is connected in series between the negative output ports of two adjacent photovoltaic units, and one protection switch module is connected in series between the positive output port of each photovoltaic unit and the positive direct current bus;

Or, in the first photovoltaic unit group, one protection switch module is connected in series between the negative output ports of two adjacent photovoltaic units, and the same protection switch module is connected in series between the positive output port and the positive direct current bus of each photovoltaic unit.

Preferably, in the first photovoltaic unit group, one protection switch module is connected in series between the positive output ports of every two adjacent photovoltaic units, and one protection switch module is connected in series between the negative output ports of every two adjacent photovoltaic units.

Preferably, each two adjacent photovoltaic units are serially connected with one protection switch module between the positive output ports, the number of the protection switch modules and the number of the photovoltaic units are M, the first photovoltaic unit is serially connected with the positive output port of the photovoltaic unit and the positive direct current bus through M protection switch modules, the second photovoltaic unit is serially connected with the positive output port of the photovoltaic unit and the positive direct current bus through M-1 protection switch modules, and the Mth photovoltaic unit is serially connected with the positive output port of the photovoltaic unit and the positive direct current bus through one protection switch module.

Further, each protection switch module corresponds to one pole number of a direct current isolating switch, and the direct current isolating switch comprises a handle and an M pole; m said protection switch modules are controlled by said handle;

The distance between the first protection switch module and the handle is smaller than that between the second protection switch module and the handle, the distance between the second protection switch module and the handle is smaller than that between the third protection switch module and the handle, and the distance between the M-th protection switch module and the handle is larger than that between any one of the other M-1 protection switch modules;

the first protection switch module is connected in series between the positive output port of the M-th photovoltaic unit and the positive direct current bus; the second protection switch module is connected in series between the positive output port of the M-1 th photovoltaic unit and the positive output port of the M-1 th photovoltaic unit; the M-th protection switch module is connected in series between the positive output port of the first photovoltaic unit and the positive output port of the second photovoltaic unit.

Still further, the photovoltaic module further comprises a second group of photovoltaic units comprising at least one photovoltaic unit comprising at least one photovoltaic assembly, the second group of photovoltaic units being configured such that failure does not occur when a failure occurs; the second photovoltaic cell group includes a positive output port connected to a positive dc bus and a negative output port connected to a negative dc bus.

Further, the positive output port of the second photovoltaic unit group is connected in series between the first protection switch module and the positive direct current bus.

Preferably, the protection switch module comprises a trip unit and a mechanical switch mechanism connected in series, wherein the trip unit is used for controlling the mechanical switch mechanism of the line to be disconnected when the reverse current of the line is larger than a first current value or the line is over-current; the release is an electromagnetic release or a thermal release.

Preferably, the protection switch module comprises a first semiconductor switch mechanism, a second semiconductor switch mechanism and a protection breakpoint which are connected in series; the first semiconductor switching mechanism and the second semiconductor switching mechanism comprise diodes and power switches which are mutually connected in parallel, and the power switches are insulated gate bipolar transistors or MOS transistors.

Preferably, the protection switch module comprises a first semiconductor switch mechanism, a second semiconductor switch mechanism and a first protection breakpoint which are connected in series, and further comprises a second protection breakpoint which is connected in parallel with the first semiconductor switch mechanism, the second semiconductor switch mechanism and the first protection breakpoint; the first semiconductor switching mechanism and the second semiconductor switching mechanism comprise diodes and power switches which are mutually connected in parallel, and the power switches are insulated gate bipolar transistors or MOS transistors.

Preferably, the photovoltaic power generation system further comprises a DC-AC converter, and the DC-AC converter and the multi-path DC-DC converter form an inverter;

the positive output ports of the multi-path DC-DC converter are connected to the positive input ports of the DC-AC converter in parallel, and the negative output ports of the multi-path DC-DC converter are connected to the negative input ports of the DC-AC converter in parallel.

Preferably, the multi-path DC-DC converter forms a direct current combiner box; the positive output ports of the multipath DC-DC converters are connected in parallel to form a positive output port of the direct current combiner box; the negative output ports of the multipath DC-DC converters are connected in parallel to form the negative output port of the direct current combiner box.

Preferably, the photovoltaic power generation system further comprises a protector, and the protector and the photovoltaic module are connected in series or in parallel; the protector includes a combination of one or more of a fuse, a circuit breaker, and an optimizer.

A photovoltaic inverter comprising a DC-AC converter, the photovoltaic inverter further comprising a photovoltaic power generation system as described above.

A direct current combiner box comprises a plurality of paths of DC-DC converters used for being connected into a photovoltaic module;

the photovoltaic module comprises at least one photovoltaic unit group, wherein the photovoltaic unit group comprises a photovoltaic unit, and the photovoltaic unit comprises at least one photovoltaic assembly;

The DC-DC converter comprises a plurality of protection switch modules, a direct current bus and a DC-DC circuit;

the direct current bus is connected with the input end of the DC-DC circuit, and the output end of the DC-DC circuit is the output end of the DC-DC converter; the direct current bus comprises a positive direct current bus and a negative direct current bus;

the protection switch module is used for controlling the circuit to be disconnected when the reverse current of the circuit is larger than a first current value or the circuit is over-current;

the positive output ports of the multipath DC-DC converters are connected in parallel to form a positive output port of the direct current combiner box; the negative output ports of the multipath DC-DC converters are connected in parallel to form a negative output port of the direct current combiner box;

the photovoltaic unit group comprises a first photovoltaic unit group, wherein the first photovoltaic unit group comprises M photovoltaic units which are connected in parallel, M is a positive integer greater than or equal to 2, and each photovoltaic unit comprises a positive output port connected to a positive direct current bus and a negative output port connected to a negative direct current bus; the number of the protection switch modules is greater than or equal to M, at least one protection switch module is connected in series between the positive output ports of every two adjacent photovoltaic units, and/or at least one protection switch module is connected in series between the negative output ports of every two adjacent photovoltaic units.

Compared with the prior art, the utility model has the following advantages:

according to the photovoltaic power generation system, the photovoltaic inverter and the direct current combiner box, the first photovoltaic unit group comprises M photovoltaic units which are connected in parallel, at least one protection switch module is connected between positive output ports of every two adjacent photovoltaic units in series, and/or at least one protection switch module is connected between negative output ports of every two adjacent photovoltaic units in series, so that two or more protection switches are arranged on a branch where the M-1 photovoltaic units are located on the premise that the protection switches are not additionally arranged, multiple protection during faults is realized, namely any one protection switch on the branch where the faults occur is disconnected, and a fault channel between the circuit and the other circuit can be cut off.

In a further preferred scheme, according to the distances between different protection switch modules and the handle, the connection sequence of the different protection switch modules is optimized, so that the fault risk that the number of poles far away from the side of the handle is easy to cause poor tripping can be effectively reduced.

Drawings

In order to more clearly illustrate the technical solutions of the present utility model, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present utility model, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a DC isolating switch;

FIG. 2 is a schematic diagram of a conventional protection circuit;

FIG. 3 is a schematic diagram of a branch circuit according to an embodiment of the present utility model;

FIG. 4 is a schematic diagram of another branch circuit according to an embodiment of the present utility model;

FIG. 5 is a schematic diagram of a further branch circuit according to an embodiment of the present utility model;

FIG. 6 is a schematic diagram of a further branch circuit according to an embodiment of the present utility model;

fig. 7 is a schematic diagram of a photovoltaic power generation system according to an embodiment of the present utility model;

FIG. 8 is a schematic diagram of another photovoltaic power generation system according to an embodiment of the present utility model;

FIG. 9 is a schematic diagram of yet another photovoltaic power generation system according to an embodiment of the present utility model;

FIG. 10 is a schematic diagram of yet another photovoltaic power generation system according to an embodiment of the present utility model;

FIG. 11 is a schematic diagram of another photovoltaic power generation system according to an embodiment of the present utility model;

FIG. 12 is a schematic view of yet another photovoltaic power generation system according to an embodiment of the present utility model;

FIG. 13 is a schematic view of yet another photovoltaic power generation system according to an embodiment of the present utility model;

FIG. 14 is a schematic view of another photovoltaic power generation system according to an embodiment of the present utility model;

FIG. 15 is a schematic view of yet another photovoltaic power generation system according to an embodiment of the present utility model;

FIG. 16 is a schematic diagram of yet another photovoltaic power generation system according to an embodiment of the present utility model;

FIG. 17 is a schematic diagram of another photovoltaic power generation system according to an embodiment of the present utility model;

FIG. 18 is a schematic diagram of yet another photovoltaic power generation system provided by an embodiment of the present utility model;

FIG. 19 is a schematic view of yet another photovoltaic power generation system according to an embodiment of the present utility model;

FIG. 20 is a schematic diagram of another photovoltaic power generation system according to an embodiment of the present utility model;

FIG. 21 is a schematic view of yet another photovoltaic power generation system according to an embodiment of the present utility model;

FIG. 22 is a schematic diagram of yet another photovoltaic power generation system according to an embodiment of the present utility model;

FIG. 23 is a schematic diagram of another photovoltaic power generation system according to an embodiment of the present utility model;

fig. 24 is a schematic structural diagram of a protection switch module according to an embodiment of the present utility model;

fig. 25 is a schematic diagram of another structure of a protection switch module according to an embodiment of the present utility model;

fig. 26 is a schematic diagram of a photovoltaic inverter according to an embodiment of the present utility model;

fig. 27 is a schematic diagram of a dc combiner box according to an embodiment of the present utility model.

Detailed Description

In order to boost the direct current ratio (the ratio of the power of the photovoltaic unit to the input power of the photovoltaic inverter) of the photovoltaic power generation system, at least two paths of photovoltaic units are generally connected to each path of MPPT devices. In the dc isolating switch shown in fig. 1, the power 1-power 6 are connected in series, and each pair of power forms a switching unit, wherein power 1-power 4 is easy to trip, and finally power 5-power 6 is easy to have a problem of poor trip. If the branch circuit of each path of photovoltaic unit is required to be ensured to be broken when faults occur, a plurality of protection switches are required to be additionally arranged on each branch circuit, and the cost is high. As shown in fig. 2, 200 'is a DC-DC converter, 201' is a DC-DC circuit, when the power 5 and power 6 are simultaneously not tripped and the power 6 fails, the power 4/5 will reversely sink current to the power 6, the current reaches 2×isc, and the current exceeds the current range that the power 6 can bear, resulting in damage to the power 6.

Preferred embodiments of the present utility model will be described in detail below with reference to the attached drawings so that the advantages and features of the present utility model can be more easily understood by those skilled in the art. The description of these embodiments is provided to assist understanding of the present utility model, but is not intended to limit the present utility model. In addition, technical features of the embodiments of the present utility model described below may be combined with each other as long as they do not collide with each other.

The single-path photovoltaic unit in the following embodiment may include one photovoltaic module, and may also be formed by connecting a plurality of photovoltaic modules in series and parallel, for example, the plurality of photovoltaic modules are connected in series to form a photovoltaic group string, and the plurality of photovoltaic group strings are connected in parallel to form the photovoltaic unit. The specific number of the photovoltaic modules included in the photovoltaic unit is not specifically limited, and those skilled in the art may set the number according to actual needs, and the electrical parameters of the individual photovoltaic modules in the embodiment of the present application are not specifically limited.

The output voltages of the multiple photovoltaic units connected with the same DC-DC converter may be the same or different, and the embodiments of the present application are not particularly limited.

According to the DC-DC converter of the photovoltaic power generation system, the photovoltaic units can be connected with the DC bus in parallel in the DC-DC converter, so that output currents of the photovoltaic units are collected to the DC bus to form a branch, and the existence mode of the branch is specifically described below.

As shown in fig. 3, the branch includes a photovoltaic unit 100, and the photovoltaic unit 100 includes a photovoltaic module 101a1 and a photovoltaic module 101a2 connected in parallel.

As shown in fig. 4, the branch includes a photovoltaic unit 100, and the photovoltaic unit 100 includes a photovoltaic module 101a1, a photovoltaic module 101a2, and a photovoltaic module 101a3 connected in parallel.

As shown in fig. 5, the branch circuit includes a path of photovoltaic unit 100, where the path of photovoltaic unit 100 includes a parallel photovoltaic module 101a1, a photovoltaic module 101a2 and a photovoltaic module 101a3, where the photovoltaic module 101a1 is further connected in series with a protector 102a1, the photovoltaic module 101a2 is further connected in series with the protector 102a2, and the photovoltaic module 101a3 is further connected in series with the protector 102a 3. The protector includes a combination of one or more of a fuse, a circuit breaker, and an optimizer, which will not be described in detail later.

As shown in fig. 6, the branch circuit includes a path of photovoltaic unit 100, where the path of photovoltaic unit 100 includes a parallel photovoltaic module 101a1, a photovoltaic module 101a2 and a photovoltaic module 101a3, where the photovoltaic module 101a1 and the protector 102a1 are connected in series and then are connected in series with the protector 102a2, the photovoltaic module 101a2 and the protector 102a2 are connected in series, and the photovoltaic module 101a3 is connected in series with the protector 102a 3.

It can be understood that the branch circuit in the embodiment of the present application is a concept in the electrical field, and refers to a path through which the branch current that is led into the dc bus flows, taking fig. 3 as an example, the path in which the photovoltaic module 101a1 is located may be referred to as a branch circuit, and the path formed after the photovoltaic module 101a1 and the photovoltaic module 101a2 are connected in parallel may also be referred to as a branch circuit. The positive output ends of the photovoltaic units (photovoltaic modules) are collected to be the positive output ends of the branches, and the negative output ends of the photovoltaic units (photovoltaic modules) are collected to be the negative output ends of the branches. The "branch" in the following embodiments refers specifically to a general term for all branches except the trunk (dc bus).

In the following, a photovoltaic power generation system including one DC-DC converter is taken as an example, and the principle when the photovoltaic power generation system includes multiple DC-DC converters is similar, which is not described in detail in this application.

As shown in fig. 7, the photovoltaic power generation system includes a one-way DC-DC converter 200 for switching in the photovoltaic module 1. The DC-DC converter 200 includes a plurality of protection switch modules S1-sq+p+2n+x, a direct current bus, and a DC-DC circuit. The DC-DC converter 200 further comprises at least one input interface. The input interface is used for connecting the photovoltaic module 1. The photovoltaic module 1 comprises in particular at least one photovoltaic cell group comprising photovoltaic cells comprising at least one photovoltaic module. The input interface is connected with a direct current bus through a plurality of protection switch modules, the direct current bus is connected with the input end of the DC-DC circuit 201, and the output end of the DC-DC circuit 201 is the output end of the DC-DC converter 200. The protection switch module is used for controlling the circuit to be disconnected when the reverse current of the circuit is larger than a first current value or the circuit is in overcurrent. The DC-DC circuit 201 may be specifically a Boost (Boost) circuit, a Buck (Buck) circuit, or a Buck-Boost (Buck-Boost) circuit.

Specifically, the photovoltaic unit group includes a first photovoltaic unit group 11, where the first photovoltaic unit group 11 includes M photovoltaic units 100 connected in parallel, and M is a positive integer greater than or equal to 2. Each photovoltaic unit 100 includes a positive output port connected to a positive dc bus and a negative output port connected to a negative dc bus. The number of the protection switch modules is greater than or equal to M, at least one protection switch module is connected in series between the positive output ports of every two adjacent photovoltaic units 100, and/or at least one protection switch module is connected in series between the negative output ports of every two adjacent photovoltaic units 100.

The photovoltaic cell group further comprises a second photovoltaic cell group 12, the second photovoltaic cell group 12 comprising at least one photovoltaic cell, the photovoltaic cell comprising at least one photovoltaic module. The second photovoltaic cell group 12 is configured such that no failure occurs when it fails. Specifically, taking fig. 3 as an example, when the photovoltaic module 101a1 fails and is shorted, the photovoltaic module 101a2 injects a fault voltage or current into the photovoltaic module 101a 1. When the failure current injected into the photovoltaic module 101a2 is insufficient and causes the photovoltaic module 101a1 and the connection cable to fail, it is considered that no failure occurs. When two PV strings are connected in series and parallel, the two PV strings are respectively named PVA and PVB, wherein the PVA strings are short-circuited or reversely connected, the PVB strings can output short-circuit current to the PVA, but the PVA power generating unit and the connected cable can bear the short-circuit current of the PVB, at this time, even if the PVA is short-circuited, the problem of PVA damage can not occur, so that the two PV strings can be connected in series and parallel as the second PV unit group in the embodiment.

In particular to the present embodiment, as shown in fig. 7, the photovoltaic module 1 includes four types of photovoltaic cell groups of ClassA, classB, classC and ClassD. Wherein ClassA and ClassB belong to the second group of photovoltaic cells 12 and classc and ClassD belong to the first group of photovoltaic cells 11. The ClassA photovoltaic unit group comprises Q photovoltaic units, each photovoltaic unit comprises a photovoltaic module, and each path of photovoltaic unit is provided with a protection switch module, as shown in S1 in the figure. Since the ClassA belongs to the second photovoltaic unit group 12, even if S1 fails, it can be ensured that the relevant photovoltaic modules of this path will not be damaged. The ClassB photovoltaic unit group comprises P photovoltaic units, each photovoltaic unit comprises two photovoltaic modules connected in parallel, and each photovoltaic unit is provided with a protection switch module, as shown by SQ+1 in the figure. Since ClassB belongs to the second photovoltaic cell group 12, even if SQ+1 fails, the related photovoltaic modules of the path can be ensured not to be damaged.

The ClassC photovoltaic unit group comprises N groups of photovoltaic unit groups (namely M=2) consisting of two photovoltaic units, each photovoltaic unit comprises two photovoltaic modules connected in parallel, wherein a protection switch module SQ+P+1 is connected in series between a positive output port A of a first photovoltaic unit and a positive output port B of an adjacent second photovoltaic unit, and a protection switch module SQ+P+2 is further arranged between the positive output port B of the second photovoltaic unit and a positive direct current bus, so that the protection switch module SQ+P+1 and the protection switch module SQ+P+2 can both control the line on-off of a branch circuit where the first photovoltaic unit is located, and even if one of the two protection switch modules fails, the other protection switch module can also control the branch circuit to break, thereby realizing multiple protection in the case of failure.

The photovoltaic unit group of the ClassD comprises X groups of photovoltaic unit groups (namely M=4) consisting of four photovoltaic units, each photovoltaic unit comprises two photovoltaic modules connected in parallel, wherein a protection switch module SQ+P+2N+1 is connected in series between a positive output port C of a first photovoltaic unit and a positive output port D of an adjacent second photovoltaic unit, a protection switch module SQ+P+2N+2 is connected in series between the positive output port D of the second photovoltaic unit and a positive output port E of an adjacent third photovoltaic unit, and a protection switch module SQ+P+2N+M is arranged between a positive output port F of an Mth photovoltaic unit and a positive direct current bus. The positive output port C of the first photovoltaic unit is connected with the positive direct current bus in series with M protection switch modules, the positive output port D of the second photovoltaic unit is connected with the positive direct current bus in series with M-1 protection switches, and the positive output port F of the Mth photovoltaic unit is connected with the positive direct current bus in series with 1 protection switch module.

Further, each protection switch module corresponds to one pole number (as shown in fig. 1) of a direct current isolating switch, the direct current isolating switch comprises a handle 1 'and an M pole, and the M protection switch modules are controlled by the handle 1'. The handle 1' is specifically an electric control handle, and a signal is sent to a chip inside the handle 1' through a controller so as to control the handle 1 '. Among the M protection switch modules, the first protection switch module is at a smaller distance from the handle 1' than the second protection switch module. The second protection switch module is at a smaller distance from the handle 1' than the third protection switch module. The distance between the M-th protection switch module and the handle 1 'is larger than the distance between any one of the other M-1 protection switches and the handle 1'.

The first protection switch module (i.e., SQ+P+2N+M) is connected in series between the positive output port (i.e., F) of the Mth photovoltaic unit and the positive DC bus. The second protection switch module is connected in series between the positive output port of the M-1 th photovoltaic unit and the positive output port of the M-1 th photovoltaic unit. The M-th protection switch module (namely SQ+P+2N+1) is connected in series between the positive output port (namely C) of the first photovoltaic unit and the positive output port (namely D) of the second photovoltaic unit.

According to the distances between different protection switch modules and the handle, the connection sequence of the different protection switch modules is optimized, so that the fault risk that the tripping failure easily occurs in the pole number far away from the side of the handle can be effectively reduced.

It should be noted that, the connection order of the protection switch modules may also be adjusted according to actual needs to meet the safety requirements of the photovoltaic power generation system, which is not limited herein.

The four types of photovoltaic cell groups ClassA, classB, classC and ClassD shown in fig. 7 are just one example shown. In other embodiments, for example, classB, classC and ClassD may be combined to form a photovoltaic power generation system, or ClassA and ClassD may be combined to form a photovoltaic power generation system, or only ClassD may form a photovoltaic power generation system, or the like. That is, various combinations may be made to construct a photovoltaic power generation system, while ensuring that there is a class d (i.e., a first photovoltaic cell group).

The photovoltaic power generation system as shown in fig. 8 to 12 includes two photovoltaic units, wherein a protection switch module S1 is connected in series between the positive output port a of the first photovoltaic unit 101a1 and the positive output port B of the second photovoltaic unit 101a2, and a protection switch module S2 is connected in series between the positive output port B of the second photovoltaic unit 101a2 and the positive dc bus. And a protection switch module is not arranged between the negative output ports of the two photovoltaic units and the negative direct current bus. Wherein the two photovoltaic units in fig. 9 each comprise one photovoltaic module. In fig. 10, a first photovoltaic unit 101a1 includes one photovoltaic module, and a second photovoltaic unit 101a2 includes two photovoltaic modules. In fig. 11, a first photovoltaic unit 101a1 includes two photovoltaic modules, and a second photovoltaic unit 101a2 includes one photovoltaic module. The two photovoltaic units in fig. 12 each include two photovoltaic modules. The number of the photovoltaic modules in each path of protection unit is not limited, and the photovoltaic modules can be combined in a series-parallel connection mode, and can be additionally connected with a protector, so that the application is not repeated.

The photovoltaic power generation system shown in fig. 13 includes two photovoltaic units, wherein a protection switch module S1 is connected in series between the positive output port a of the first photovoltaic unit 101a1 and the positive output port B of the second photovoltaic unit 101a2, and a protection switch module S2 is connected in series between the positive output port B of the second photovoltaic unit 101a2 and the positive dc bus. And a protection switch module is respectively connected in series between the negative output ports of the two photovoltaic units and the negative direct current bus. Specifically, a protection switch S3 is connected in series between the negative output port C of the first photovoltaic unit 101a1 and the negative dc bus, and a protection switch S4 is connected in series between the negative output port D of the second photovoltaic unit 101a2 and the negative dc bus.

The photovoltaic power generation system shown in fig. 14 includes two photovoltaic units, wherein a protection switch module S1 is connected in series between a positive output port a of a first photovoltaic unit 101a1 and a positive output port B of a second photovoltaic unit 101a2, and a protection switch module S2 is connected in series between the positive output port B of the second photovoltaic unit 101a2 and a positive dc bus. The same protection switch module S3 is connected in series between the negative output ports of the two photovoltaic units and the negative direct current bus. Specifically, a protection switch module S3 is connected in series between the negative output port C of the first photovoltaic unit 101a1 and the negative dc bus, and a protection switch module S3 is also connected in series between the negative output port D of the second photovoltaic unit 101a2 and the negative dc bus.

The photovoltaic power generation system shown in fig. 15 includes two photovoltaic units, wherein a protection switch module S1 is connected in series between a positive output port a of a first photovoltaic unit 101a1 and a positive output port B of a second photovoltaic unit 101a2, and a protection switch module S2 is connected in series between the positive output port B of the second photovoltaic unit 101a2 and a positive dc bus. A protection switch module S3 is connected in series between the negative output port C of the first photovoltaic unit 101a1 and the negative output port D of the second photovoltaic unit 101a2, and a protection switch module S4 is connected in series between the negative output port D of the second photovoltaic unit 101a2 and the negative dc bus.

The photovoltaic power generation system shown in fig. 16 includes two photovoltaic units, wherein a protection switch module S1 is connected in series between the negative output port a of the first photovoltaic unit 101a1 and the negative output port B of the second photovoltaic unit 101a2, and a protection switch module S2 is connected in series between the negative output port B of the second photovoltaic unit 101a2 and the negative dc bus. And a protection switch module is not arranged between the positive output ports of the two photovoltaic units and the positive direct current bus.

The photovoltaic power generation system shown in fig. 17 includes two photovoltaic units, a protection switch module S2 is connected in series between the negative output port a of the first photovoltaic unit 101a1 and the negative output port B of the second photovoltaic unit 101a2, and a protection switch module S3 is connected in series between the negative output port B of the second photovoltaic unit 101a2 and the negative dc bus. The same protection switch module S1 is connected in series between the positive output ports of the two photovoltaic units and the positive direct current bus. Specifically, the protection switch module S3 is connected in series between the positive output port C of the first photovoltaic unit 101a1 and the positive dc bus, and the protection switch module S3 is also connected in series between the positive output port D of the second photovoltaic unit 101a2 and the positive dc bus.

The photovoltaic power generation system shown in fig. 18 includes M photovoltaic units, where a protection switch module S1 is connected in series between the positive output port a of the first photovoltaic unit 101a1 and the positive output port B of the second photovoltaic unit 101a2, a protection switch module S2 is connected in series between the positive output port B of the second photovoltaic unit 101a2 and the positive output port C of the third photovoltaic unit 101a3, and a protection switch module SM is connected in series between the positive output port D of the mth photovoltaic unit 101aM and the positive dc bus. And a protection switch is not arranged between the negative output ports of the M photovoltaic units and the negative direct current buses.

The photovoltaic power generation system shown in fig. 19 includes M photovoltaic units, a protection switch module S1 is connected in series between the negative output port a of the first photovoltaic unit 101a1 and the negative output port B of the second photovoltaic unit 101a2, a protection switch module S2 is connected in series between the negative output port B of the second photovoltaic unit 101a2 and the negative output port C of the third photovoltaic unit 101a3, and a protection switch module SM is connected in series between the negative output port D of the mth photovoltaic unit 101aM and the negative dc bus. And a protection switch is not arranged between positive output ports of the M photovoltaic units and the positive direct current bus.

The photovoltaic power generation system shown in fig. 20 includes M photovoltaic units (100 a1-100 aM) of the first photovoltaic unit group 11 and one photovoltaic unit 100B1 of the second photovoltaic unit group 12, a protection switch module S1 is connected in series between the positive output port a of the first photovoltaic unit 101a1 and the positive output port B of the second photovoltaic unit 101a2, a protection switch module S2 is connected in series between the positive output port B of the second photovoltaic unit 101a2 and the positive output port C of the third photovoltaic unit 101a3, and a protection switch module SM is connected in series between the positive output port D of the mth photovoltaic unit 101aM and the photovoltaic unit 100B 1. And a protection switch is not arranged between the negative output ports of the M photovoltaic units and the negative direct current buses. Since the photovoltaic unit 100b1 is configured as one photovoltaic unit of the second photovoltaic unit group 12, even if the branch fails, the sum of the currents of all the other branches is insufficient to damage the photovoltaic module of the branch in which the photovoltaic unit 100b1 is located.

The photovoltaic power generation system shown in fig. 21 includes M photovoltaic units (100 a1-100 aM) of the first photovoltaic unit group 11 and one photovoltaic unit 100B1 of the second photovoltaic unit group 12, a protection switch module S1 is connected in series between the negative output port a of the first photovoltaic unit 101a1 and the negative output port B of the second photovoltaic unit 101a2, a protection switch module S2 is connected in series between the negative output port B of the second photovoltaic unit 101a2 and the negative output port C of the third photovoltaic unit 101a3, and a protection switch module SM is connected in series between the negative output port D of the mth photovoltaic unit 101aM and the negative output port of the photovoltaic unit 100B1. And a protection switch is not arranged between positive output ports of the M photovoltaic units and the positive direct current bus.

The photovoltaic power generation system shown in fig. 22 includes the photovoltaic units (100 a1-100 aM) of the M first photovoltaic unit groups 11 and the photovoltaic units 100b1 of one second photovoltaic unit group 12. A protection switch module S1 is connected in series between the positive output port a of the first photovoltaic unit 101a1 and the positive output port B of the second photovoltaic unit 101a2, and a protection switch module S3 is not connected in series between the positive output port B of the second photovoltaic unit 101a2 and the positive output port C of the third photovoltaic unit 101a3, but is connected in series between the negative output port F of the second photovoltaic unit 101a2 and the negative output port G of the third photovoltaic unit 101a 3. The protection switch module SM is connected in series between the positive output port D of the mth photovoltaic unit 101aM and the positive output port of the photovoltaic unit 100b1.

The photovoltaic power generation system shown in fig. 23 includes the photovoltaic units (100 a1 to 100 aM) of the M first photovoltaic unit groups 11. A protection switch module S1 is connected in series between the positive output port a of the first photovoltaic unit 101a1 and the positive output port B of the second photovoltaic unit 101a2, a protection switch module S2 is connected in series between the positive output port B of the second photovoltaic unit 101a2 and the positive output port C of the third photovoltaic unit 101a3, and a protection switch module SM is connected in series between the positive output port D of the mth photovoltaic unit 101aM and the positive dc bus. The same protection switch module SM+1 is connected in series between the negative output ports of the M photovoltaic units and the negative direct current buses.

The protection switch module in this embodiment includes a trip unit and a mechanical switch mechanism connected in series, where the trip unit is configured to control the mechanical switch mechanism of the line to be disconnected when the reverse current of the line is greater than the first current value or there is an overcurrent in the line. The release may be an electromagnetic release that controls the mechanical structure to release through an electrical coil. The trip device may also be a thermal trip device, and is not specifically limited herein.

As shown in fig. 24, the protection switch module may further include a first semiconductor switching mechanism 21, a second semiconductor switching mechanism 22, and a protection breakpoint 23 connected in series. The first semiconductor switching mechanism 21 and the second semiconductor switching mechanism 22 comprise diodes and power switches which are connected in parallel, and the power switches are insulated gate bipolar transistors or MOS transistors. The first semiconductor switching mechanism 21 and the second semiconductor switching mechanism 22 are disposed opposite to each other (current flows in opposite directions). The semiconductor device can be used for rapidly shutting off the circuit, and meanwhile, a breakpoint is added to be used as isolation to meet the safety requirement.

As shown in fig. 25, the protection switch module may further include a first semiconductor switch mechanism, a second semiconductor switch mechanism, and a first protection break point connected in series. The protection switch module further comprises a second protection breakpoint, and the second protection breakpoint is connected with the first semiconductor switch mechanism, the second semiconductor switch mechanism and the first protection breakpoint in parallel. The first semiconductor switching mechanism 21 and the second semiconductor switching mechanism 22 comprise diodes and power switches which are connected in parallel, and the power switches are insulated gate bipolar transistors or MOS transistors. The first semiconductor switching mechanism 21 and the second semiconductor switching mechanism 22 are disposed opposite to each other (current flows in opposite directions). The semiconductor device can be used for rapidly turning off the circuit, and two breakpoints are set for isolation use at the same time so as to meet the safety requirements.

The present embodiment also discloses a photovoltaic inverter 6, as shown in fig. 26, the photovoltaic inverter 6 includes the photovoltaic power generation system and the DC-AC converter 5 described above. In particular, the photovoltaic inverter 6 comprises a DC-AC converter 5 and a multi-channel DC-DC converter 200 for switching in the photovoltaic module 1. The different structures of the constituent mechanisms of the specific photovoltaic modules and the protection switch modules are as described above, and detailed descriptions thereof are omitted here.

The present embodiment also discloses a direct current combiner box 7, as shown in fig. 27, the direct current combiner box 7 includes a multi-path DC-DC converter 200 for accessing the photovoltaic module 1. The different structures of the constituent mechanisms of the specific photovoltaic modules and the protection switch modules are as described above, and detailed descriptions thereof are omitted here.

In summary, the photovoltaic power generation system, the photovoltaic inverter and the direct current combiner box in the embodiment have the following advantages:

1. by arranging the first photovoltaic unit group, the first photovoltaic unit group comprises M photovoltaic units which are connected in parallel, at least one protection switch module is connected in series between positive output ports of every two adjacent photovoltaic units, and/or at least one protection switch module is connected in series between negative output ports of every two adjacent photovoltaic units, the arrangement can realize multiple protection during faults by arranging two or more protection switches on branches where the M-1 photovoltaic units are positioned on the premise that the protection switches are not additionally arranged, namely, any one protection switch on the branch where the faults occur is disconnected, and a fault channel between the circuit and another circuit can be cut off;

2. according to the distances between different protection switch modules and the handle, the connection sequence of the different protection switch modules is optimized, so that the fault risk that the number of poles far away from the handle side is easy to generate poor tripping can be effectively reduced;

3. By arranging the second photovoltaic unit group, the number of the protection switch modules can be reduced under the condition that the photovoltaic devices are not damaged;

4. the protection switch modules in the first photovoltaic unit group have various setting modes and can be flexibly combined according to actual needs;

5. when any branch fails, the protection switch is disconnected, so that the photovoltaic units of other branches cannot output current to the circuit where the photovoltaic unit with short-circuit failure is located, and the photovoltaic unit and the circuit are protected from being damaged;

6. no extra control circuit is needed, so that the implementation difficulty is reduced, and the cost is reduced.

As used in this specification and in the claims, the terms "comprises" and "comprising" merely indicate that the steps and elements are explicitly identified, and do not constitute an exclusive list, as other steps or elements may be included in a method or apparatus. The term "and/or" as used herein includes any combination of one or more of the associated listed items.

It should be noted that, unless otherwise specified, when a feature is referred to as being "fixed" or "connected" to another feature, it may be directly or indirectly fixed or connected to the other feature. Further, the descriptions of the upper, lower, left, right, etc. used in the present utility model are merely with respect to the mutual positional relationship of the constituent elements of the present utility model in the drawings.

The above-described embodiments are provided for illustrating the technical concept and features of the present utility model, and are intended to be preferred embodiments for those skilled in the art to understand the present utility model and implement the same according to the present utility model, not to limit the scope of the present utility model. All equivalent changes or modifications made according to the principles of the present utility model should be construed to be included within the scope of the present utility model.

Claims (16)

1. A photovoltaic power generation system includes a DC-DC converter for switching in a photovoltaic module;

the photovoltaic module comprises at least one photovoltaic unit group, wherein the photovoltaic unit group comprises a photovoltaic unit, and the photovoltaic unit comprises at least one photovoltaic assembly;

the DC-DC converter comprises a plurality of protection switch modules, a direct current bus and a DC-DC circuit;

the direct current bus is connected with the input end of the DC-DC circuit, and the output end of the DC-DC circuit is the output end of the DC-DC converter; the direct current bus comprises a positive direct current bus and a negative direct current bus;

the protection switch module is used for controlling the circuit to be disconnected when the reverse current of the circuit is larger than a first current value or the circuit is over-current;

it is characterized in that the method comprises the steps of,

the photovoltaic unit group comprises a first photovoltaic unit group, wherein the first photovoltaic unit group comprises M photovoltaic units which are connected in parallel, M is a positive integer greater than or equal to 2, and each photovoltaic unit comprises a positive output port connected to the positive direct current bus and a negative output port connected to the negative direct current bus; the number of the protection switch modules is greater than or equal to M, at least one protection switch module is connected in series between the positive output ports of every two adjacent photovoltaic units, and/or at least one protection switch module is connected in series between the negative output ports of every two adjacent photovoltaic units.

2. The photovoltaic power generation system according to claim 1, wherein in the first photovoltaic unit group, one protection switch module is connected in series between positive output ports of every two adjacent photovoltaic units, and the protection switch module is not arranged between the negative output ports of the photovoltaic units and the negative direct current bus;

or, in the first photovoltaic unit group, one protection switch module is connected in series between the positive output ports of two adjacent photovoltaic units, and one protection switch module is connected in series between the negative output port of each photovoltaic unit and the negative direct current bus;

or, in the first photovoltaic unit group, one protection switch module is connected in series between the positive output ports of two adjacent photovoltaic units, and the same protection switch module is connected in series between the negative output port and the negative direct current bus of each photovoltaic unit.

3. The photovoltaic power generation system according to claim 1, wherein in the first photovoltaic unit group, one protection switch module is connected in series between the negative output ports of every two adjacent photovoltaic units, and the protection switch module is not arranged between the positive output port of the photovoltaic unit and the positive direct current bus;

Or, in the first photovoltaic unit group, one protection switch module is connected in series between the negative output ports of two adjacent photovoltaic units, and one protection switch module is connected in series between the positive output port of each photovoltaic unit and the positive direct current bus;

or, in the first photovoltaic unit group, one protection switch module is connected in series between the negative output ports of two adjacent photovoltaic units, and the same protection switch module is connected in series between the positive output port and the positive direct current bus of each photovoltaic unit.

4. The photovoltaic power generation system according to claim 1, wherein in the first photovoltaic unit group, one protection switch module is connected in series between positive output ports of every two adjacent photovoltaic units, and one protection switch module is connected in series between negative output ports of every two adjacent photovoltaic units.

5. The photovoltaic power generation system according to claim 1, wherein one protection switch module is connected in series between the positive output ports of every two adjacent photovoltaic units, the number of the protection switch modules and the number of the photovoltaic units are M, the first protection switch module is connected in series between the positive output port of the photovoltaic unit and the positive dc bus, the second protection switch module is connected in series between the positive output port of the photovoltaic unit and the positive dc bus, and the M-1 protection switch module is connected in series between the positive output port of the mth photovoltaic unit and the positive dc bus.

6. The photovoltaic power generation system of claim 5, wherein each of the protection switch modules corresponds to one pole of a dc isolating switch, the dc isolating switch comprising a handle and an M pole; m said protection switch modules are controlled by said handle;

the distance between the first protection switch module and the handle is smaller than that between the second protection switch module and the handle, the distance between the second protection switch module and the handle is smaller than that between the third protection switch module and the handle, and the distance between the M-th protection switch module and the handle is larger than that between any one of the other M-1 protection switch modules;

the first protection switch module is connected in series between the positive output port of the M-th photovoltaic unit and the positive direct current bus; the second protection switch module is connected in series between the positive output port of the M-1 th photovoltaic unit and the positive output port of the M-1 th photovoltaic unit; the M-th protection switch module is connected in series between the positive output port of the first photovoltaic unit and the positive output port of the second photovoltaic unit.

7. The photovoltaic power generation system of claim 6, wherein the photovoltaic module further comprises a second group of photovoltaic cells, the second group of photovoltaic cells comprising at least one photovoltaic cell, the photovoltaic cell comprising at least one photovoltaic module, the second group of photovoltaic cells configured to fail without failure; the second photovoltaic cell group includes a positive output port connected to a positive dc bus and a negative output port connected to a negative dc bus.

8. The photovoltaic power generation system of claim 7, wherein the positive output port of the second photovoltaic cell group is connected in series between a first one of the protection switch modules and the positive dc bus.

9. The photovoltaic power generation system of claim 1, wherein the protection switch module comprises a trip unit and a mechanical switch mechanism connected in series, the trip unit being configured to control the mechanical switch mechanism of the line to open when a reverse current of the line is greater than a first current value or there is an overcurrent of the line; the release is an electromagnetic release or a thermal release.

10. The photovoltaic power generation system of claim 1, wherein the protection switch module comprises a first semiconductor switch mechanism, a second semiconductor switch mechanism, and a protection breakpoint in series; the first semiconductor switching mechanism and the second semiconductor switching mechanism comprise diodes and power switches which are mutually connected in parallel, and the power switches are insulated gate bipolar transistors or MOS transistors.

11. The photovoltaic power generation system of claim 1, wherein the protection switch module comprises a first semiconductor switch mechanism, a second semiconductor switch mechanism, and a first protection breakpoint in series, the protection switch module further comprising a second protection breakpoint, the second protection breakpoint being in parallel with the first semiconductor switch mechanism, the second semiconductor switch mechanism, and the first protection breakpoint; the first semiconductor switching mechanism and the second semiconductor switching mechanism comprise diodes and power switches which are mutually connected in parallel, and the power switches are insulated gate bipolar transistors or MOS transistors.

12. The photovoltaic power generation system of claim 1, further comprising a DC-AC converter forming an inverter with the multi-path DC-DC converter;

the positive output ports of the multi-path DC-DC converter are connected to the positive input ports of the DC-AC converter in parallel, and the negative output ports of the multi-path DC-DC converter are connected to the negative input ports of the DC-AC converter in parallel.

13. The photovoltaic power generation system of claim 1, wherein the multiple DC-DC converters form a direct current combiner box; the positive output ports of the multipath DC-DC converters are connected in parallel to form a positive output port of the direct current combiner box; the negative output ports of the multipath DC-DC converters are connected in parallel to form the negative output port of the direct current combiner box.

14. The photovoltaic power generation system of claim 1, further comprising a protector, the protector and the photovoltaic module being connected in series or in parallel; the protector includes a combination of one or more of a fuse, a circuit breaker, and an optimizer.

15. A photovoltaic inverter comprising a DC-AC converter, wherein the photovoltaic inverter further comprises a photovoltaic power generation system as claimed in any one of claims 1-14.

16. A direct current combiner box comprises a plurality of paths of DC-DC converters used for being connected into a photovoltaic module;

the photovoltaic module comprises at least one photovoltaic unit group, wherein the photovoltaic unit group comprises a photovoltaic unit, and the photovoltaic unit comprises at least one photovoltaic assembly;

the DC-DC converter comprises a plurality of protection switch modules, a direct current bus and a DC-DC circuit;

the direct current bus is connected with the input end of the DC-DC circuit, and the output end of the DC-DC circuit is the output end of the DC-DC converter; the direct current bus comprises a positive direct current bus and a negative direct current bus;

the protection switch module is used for controlling the circuit to be disconnected when the reverse current of the circuit is larger than a first current value or the circuit is over-current;

The positive output ports of the multipath DC-DC converters are connected in parallel to form a positive output port of the direct current combiner box; the negative output ports of the multipath DC-DC converters are connected in parallel to form a negative output port of the direct current combiner box;

it is characterized in that the method comprises the steps of,

the photovoltaic unit group comprises a first photovoltaic unit group, wherein the first photovoltaic unit group comprises M photovoltaic units which are connected in parallel, M is a positive integer greater than or equal to 2, and each photovoltaic unit comprises a positive output port connected to a positive direct current bus and a negative output port connected to a negative direct current bus; the number of the protection switch modules is greater than or equal to M, at least one protection switch module is connected in series between the positive output ports of every two adjacent photovoltaic units, and/or at least one protection switch module is connected in series between the negative output ports of every two adjacent photovoltaic units.