CN211860010U

CN211860010U - Photovoltaic power generation system with isolated form MPPT collection flow box

Info

Publication number: CN211860010U
Application number: CN202020852291.8U
Authority: CN
Inventors: 彭文博; 李晓磊; 高虎
Original assignee: Huaneng Clean Energy Research Institute; China Huaneng Group Co Ltd
Current assignee: Huaneng Clean Energy Research Institute; China Huaneng Group Co Ltd
Priority date: 2020-05-20
Filing date: 2020-05-20
Publication date: 2020-11-03
Anticipated expiration: 2030-05-20

Abstract

The utility model discloses a photovoltaic power generation system with isolated form MPPT collection flow box belongs to photovoltaic power generation technical field. The photovoltaic modules are connected in series to form a photovoltaic subunit string, the photovoltaic subunit string is connected with an isolated MPPT (maximum power point tracking) combiner box, and the output sides of all the isolated MPPT combiner boxes are connected in parallel and then connected to an inverter; the isolated MPPT combiner box comprises an input circuit group, a direct current bus and a control and drive module; the input circuit group comprises a plurality of MPPT and isolation modules, the input sides of the MPPT and isolation modules are connected with the photovoltaic sub-group in series, and the output sides of the MPPT and isolation modules are connected with the direct-current busbar after being connected in series. The installation mode and the wiring mode of the photovoltaic module array are not changed, particularly the maximum voltage to earth of the photovoltaic module is not improved, the direct-current voltage-withstanding grade of the modules in the photovoltaic group substrings is not improved, and the line loss and the cable consumption of the output side of the isolation type MPPT combiner box can be obviously reduced; the MPPT tracking accuracy of the system can still be kept at the photovoltaic group cascade of the conventional voltage level.

Description

Photovoltaic power generation system with isolated form MPPT collection flow box

Technical Field

The utility model belongs to the technical field of photovoltaic power generation, concretely relates to photovoltaic power generation system with isolated form MPPT collection flow box.

Background

The DC voltage level of the photovoltaic system is improved, so that the line loss is reduced, and the system cost is reduced. The conventional photovoltaic system can obtain a larger direct current voltage grade, such as 1000V or 1500V direct current voltage, by connecting the modules in series, but the photovoltaic modules in the string are required to have the insulation voltage resistance level of 1000V or 1500V simultaneously while obtaining 1000V direct current voltage and 1500V direct current voltage. Because no photovoltaic module with voltage-resistant grade above 1500V exists at present, and no related technical standard exists, the photovoltaic system is limited to be developed to a higher direct-current voltage grade.

Meanwhile, under the condition that the withstand voltage grade of the photovoltaic module meets the high-voltage requirement, obtaining better direct-current bus voltage means that more photovoltaic modules are required to be connected in series, and more series connection means higher series mismatch probability, so that improvement of system electric quantity is not facilitated.

Disclosure of Invention

In order to solve the existing problems, the utility model aims to provide a photovoltaic power generation system with isolated MPPT combiner box, which does not change the installation mode and the wiring mode of a photovoltaic module array, especially does not improve the maximum voltage to earth of the connected photovoltaic module, does not improve the direct current withstand voltage grade of the components in the photovoltaic group substring, and can obviously reduce the line loss and the cable consumption on the output side of the isolated MPPT combiner box; the MPPT tracking accuracy of the system can still be kept at the photovoltaic group cascade of the conventional voltage level.

The utility model discloses a following technical scheme realizes:

the utility model discloses a photovoltaic power generation system with isolated MPPT combiner box, a plurality of photovoltaic modules are connected in series to form a photovoltaic subgroup string, the photovoltaic subgroup string is connected with an isolated MPPT combiner box, and the output sides of all isolated MPPT combiner boxes are connected in parallel and then connected to the DC side of the inverter of the photovoltaic power generation system;

the isolated MPPT combiner box comprises an input circuit group, a direct current bus and a control and drive module; the output sides of the plurality of input circuit groups are connected in parallel and then are connected with a direct current bus, and the direct current bus is connected with the output side of the isolated MPPT combiner box; the control and drive module is connected with the input circuit group;

the input circuit group comprises a plurality of MPPT and isolation modules, the input sides of the MPPT and isolation modules are connected with the photovoltaic sub-group in series, and the output sides of the MPPT and isolation modules are connected with the direct-current busbar after being connected in series.

Preferably, the MPPT and isolation module includes an access terminal, an MPPT circuit, and an isolation circuit, which are connected in sequence; the access terminal is connected with the photovoltaic sub-group in series, and the isolation circuit is connected with the MPPT and the output side of the isolation module; the MPPT circuit and the isolation circuit are respectively connected with the control and drive module.

Further preferably, a fuse is connected between the access terminal and the MPPT circuit.

Preferably, an anti-reverse diode is connected in series between the positive electrode output side of the input circuit group and the direct current bus bar.

Preferably, a direct current breaker is connected in series between the direct current busbar and the output side of the isolated MPPT combiner box.

Preferably, a lightning protection grounding device is connected in parallel between the direct current busbar and the output side of the isolated MPPT busbar box.

Preferably, the number of MPPT and isolation modules in the input circuit group is more than or equal to 2.

Compared with the prior art, the utility model discloses following profitable technological effect has:

the utility model discloses a photovoltaic power generation system with isolated form MPPT collection flow box, photovoltaic module are not directly established ties and are formed a group cluster, but establish ties earlier by a plurality of photovoltaic module and form photovoltaic subgroup cluster, and an isolated form MPPT collection flow box is concatenated into to a plurality of photovoltaic subgroups, and the isolation control ware connects in parallel the dc-to-ac converter that inserts photovoltaic power generation system again. The isolated MPPT combiner box can not change the installation mode and the wiring mode of a photovoltaic module array, especially can not improve the maximum voltage to earth of the photovoltaic module and the direct-current voltage-withstanding grade of the components in a photovoltaic string group, the photovoltaic string group can be connected in series after passing through the isolated MPPT combiner box to increase the multiple of the direct-current voltage grade, and the line loss and the cable consumption of the output side of the isolated MPPT combiner box can be obviously reduced. Meanwhile, each photovoltaic subgroup string independently carries out maximum power point tracking, and MPPT tracking accuracy of the system can still be kept at a photovoltaic subgroup string level of a conventional voltage level.

Furthermore, the MPPT circuit in the MPPT and isolation module performs maximum power point tracking on the accessed photovoltaic sub-group strings, and the isolation circuit realizes voltage isolation of the input side and the output side.

Further, the fuse can cut off when the current is too large, and normal operation of the system is guaranteed.

Furthermore, the anti-reverse diode can prevent current from flowing reversely, and normal operation of the system is guaranteed.

Furthermore, the direct current breaker can be independently cut off when components in the circuit are in failure or leakage, and the normal operation of the whole combiner box is not influenced.

Further, the lightning protection grounding device is used for preventing lightning stroke and static damage, and the safety and the stability of the system are improved.

Drawings

Fig. 1 is a schematic view of the structural principle of the isolated MPPT combiner box of the present invention;

fig. 2 is a schematic structural diagram of the MPPT and the isolation module according to the present invention;

FIG. 3 is a schematic diagram of an input circuit set according to the present invention;

fig. 4 is the utility model discloses a photovoltaic power generation system's overall structure schematic diagram with isolated form MPPT collection flow box.

In the figure: the photovoltaic module is characterized in that 1 is a photovoltaic module, 2 is an isolated MPPT (maximum power point tracking) combiner box, 21 is an input circuit group, 211 is an MPPT and isolation module, 2111 is an access terminal, 2112 is a fuse, 2113 is an MPPT circuit, 2114 is an isolation circuit, 22 is a direct-current bus bar, 23 is a control and drive module, 24 is an anti-reverse diode, 25 is a lightning protection grounding device, 26 is a direct-current breaker and 3 is an inverter.

Detailed Description

The invention will be described in further detail with reference to the following drawings and specific examples, which are intended to illustrate and not to limit the invention:

as shown in fig. 1, the isolated MPPT bus 2 includes an input circuit group 21, a dc bus 22, and a control and driving module; the output sides of the input circuit groups 21 are connected in parallel and then are connected with the direct-current bus bar 22, and anti-reflection diodes 24 are connected in series between the positive electrode output side of the input circuit group 21 and the direct-current bus bar 22; the direct-current busbar 22 is connected with the output side of the isolated MPPT busbar box 2, and a lightning protection grounding device 25 and a direct-current breaker 26 are connected in series between the direct-current busbar 22 and the output side of the isolated MPPT busbar box 2 in parallel.

As shown in fig. 3, the input circuit group 21 includes a plurality of MPPT and isolation modules 211, the input sides of the MPPT and isolation modules 211 are connected in series with the photovoltaic sub-group, and the output sides of 2 or more than 2 adjacent MPPT and isolation modules 211 are connected in series and then connected with the dc bus bar 22.

As shown in fig. 2, the MPPT and isolation module 211 includes an access terminal 2111, an MPPT circuit 2113, and an isolation circuit 2114 connected in sequence; the access terminal 2111 is connected with the photovoltaic sub-group string, and the isolation circuit 2114 is connected with the MPPT and the output side of the isolation module 211; the MPPT 2113 and the isolation 2114 are connected to the control and drive module 23, respectively.

The positive and negative electrodes of each photovoltaic subgroup string are introduced into an MPPT circuit 2113 through an access terminal 2111 of a set of MPPT and isolation module 211, the MPPT circuit 2113 performs maximum power tracking on the photovoltaic subgroup string, then the output end of the photovoltaic subgroup string is connected into an isolation circuit 2114, and the isolation circuit 2114 has the function of electrically isolating the voltage to ground at the output end from the voltage to ground at the input end; the adjacent 2 or more MPPT and isolation modules 211 are connected in series at the output side and are connected in series with an anti-reverse diode 26 at the positive pole to form an input circuit group 21, the positive and negative output ends of the input circuit group are connected into the positive and negative direct current busbars 22 of the isolated MPPT combiner box 2, and finally the positive and negative direct current busbars pass through the direct current circuit breaker 26 and the lightning protection grounding device 25 and are output, the output voltage at the moment is improved to Nx V, wherein V is the photovoltaic group string voltage at the input side, and N is the number of the MPPT and isolation modules 211 which are connected in series. The control and driving module 23 provides the MPPT 2113 and the isolation 2114 for driving control, and collects and transmits electrical signals to the previous stage. For example, if the voltage level of a single connected photovoltaic subgroup string is 1000V, 2 or 3 photovoltaic subgroup strings are connected in series after passing through the MPPT circuit 2113 and the isolation circuit 2114 and then connected to the dc bus bar 22, the voltage level (output) of the dc bus bar 22 of the isolated MPPT bus box 2 becomes 2000V or 3000V, and the maximum voltage to ground of the output side electrode of the isolated MPPT bus box 2 will be 2000V or 3000V. However, since the input side and the output side of the isolated MPPT combiner box 2 are electrically isolated, the maximum voltage to ground voltage of the series electrode terminal of each photovoltaic sub-group is still maintained at 1000v, i.e. the voltage withstanding strength requirement of the photovoltaic module 1 is increased along with the increase of the voltage level of the direct current system.

As fig. 4, the utility model discloses a photovoltaic power generation system with isolated form MPPT collection flow box, a plurality of photovoltaic module 1 establish ties and constitute photovoltaic subgroup cluster, and a plurality of photovoltaic subgroup cluster are connected to isolated form MPPT collection flow box 2, and all isolated form MPPT collection flow box 2's output side is connected to photovoltaic power generation system's dc-to-ac converter 3 after parallelly connected. The voltage level of a photovoltaic subgroup string in front of the isolated MPPT combiner box 2 is 1000V or 1500V of a conventional photovoltaic subgroup string, and the conventional photovoltaic subgroup string is boosted to be more than 2000V-3000V after being connected in series in the isolated MPPT combiner box 2. And the direct current collecting cables behind the isolated MPPT collecting box 2 adopt 2000V or 3000V withstand voltage specifications. The outputs of the isolated MPPT combiner boxes 2 are connected in parallel at the direct current side of the inverter 3, and the grid connection is realized after the inversion of the inverter 3.

It should be noted that the above description is only one of the embodiments of the present invention, and all equivalent changes made by the system described in the present invention are included in the protection scope of the present invention. The technical field of the present invention can be replaced by other embodiments described in a similar manner, without departing from the structure of the present invention or exceeding the scope defined by the claims, which belong to the protection scope of the present invention.

Claims

1. A photovoltaic power generation system with an isolated MPPT combiner box is characterized in that a plurality of photovoltaic modules (1) are connected in series to form a photovoltaic subgroup string, the photovoltaic subgroup string is connected with an isolated MPPT combiner box (2), and the output sides of all the isolated MPPT combiner boxes (2) are connected in parallel and then connected to the direct current side of an inverter (3) of the photovoltaic power generation system;

the isolated MPPT bus box (2) comprises an input circuit group (21), a direct current bus (22) and a control and drive module (23); the output sides of the plurality of input circuit groups (21) are connected in parallel and then are connected with a direct current bus (22), and the direct current bus (22) is connected with the output side of the isolated MPPT combiner box (2); the control and drive module (23) is connected with the input circuit group (21);

the input circuit group (21) comprises a plurality of MPPT and isolation modules (211), the input sides of the MPPT and isolation modules (211) are connected with the photovoltaic sub-group in series, and the output sides of the MPPT and isolation modules (211) are connected with the direct-current busbar (22) after being connected in series.

2. The photovoltaic power generation system with the isolated MPPT combiner box of claim 1, wherein the MPPT and isolation module (211) includes an access terminal (2111), an MPPT circuit (2113) and an isolation circuit (2114) connected in sequence; the access terminal (2111) is connected with the photovoltaic subgroup string, and the isolation circuit (2114) is connected with the MPPT and the output side of the isolation module (211); the MPPT circuit (2113) and the isolation circuit (2114) are respectively connected with the control and drive module (23).

3. The photovoltaic power generation system with isolated MPPT combiner box of claim 2, wherein a fuse (2112) is connected between the access terminal (2111) and the MPPT circuit (2113).

4. The photovoltaic power generation system with the isolated MPPT combiner box of claim 1, wherein an anti-reflection diode (24) is connected in series between the positive output side of the input circuit group (21) and the DC bus bar (22).

5. The photovoltaic power generation system with the isolated MPPT combiner box of claim 1, characterized in that a DC breaker (26) is connected in series between the DC busbar (22) and the output side of the isolated MPPT combiner box (2).

6. The photovoltaic power generation system with the isolated MPPT combiner box of claim 1, characterized in that a lightning protection earth (25) is connected in parallel between the DC busbar (22) and the output side of the isolated MPPT combiner box (2).

7. The photovoltaic power generation system with the isolated MPPT combiner box of claim 1, wherein the number of MPPT and isolation modules (211) in the input circuit group (21) is greater than or equal to 2.