CN110896227A - Photovoltaic power generation system and photovoltaic inverter - Google Patents
Photovoltaic power generation system and photovoltaic inverter Download PDFInfo
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- CN110896227A CN110896227A CN201811062168.XA CN201811062168A CN110896227A CN 110896227 A CN110896227 A CN 110896227A CN 201811062168 A CN201811062168 A CN 201811062168A CN 110896227 A CN110896227 A CN 110896227A
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- 238000010248 power generation Methods 0.000 title claims abstract description 15
- 238000012423 maintenance Methods 0.000 claims abstract description 121
- 238000009413 insulation Methods 0.000 claims description 33
- 238000012544 monitoring process Methods 0.000 claims description 21
- 230000005405 multipole Effects 0.000 claims description 6
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- 101100537375 Homo sapiens TMEM107 gene Proteins 0.000 claims description 4
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- 230000010354 integration Effects 0.000 abstract description 4
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- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
- H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
- H02S40/30—Electrical components
- H02S40/32—Electrical components comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
Abstract
The invention provides a photovoltaic power generation system and a photovoltaic inverter.A maintenance switch in the photovoltaic power generation system is combined with a plug-pull wiring terminal connected with an input end, so that a combiner box in the prior art is replaced, and the combiner input of a plurality of photovoltaic group strings can be realized; the function of the direct-current power distribution cabinet is realized through the confluence branch fuse and the direct-current main switch; therefore, compared with the prior art, the photovoltaic inverter has the advantages that the system integration level is improved, and the implementation cost is reduced. Moreover, an operator can complete on-off control of the maintenance switch and the direct current main switch through the photovoltaic inverter without back-and-forth operation between the photovoltaic inverter and a plurality of header boxes which are far away from each other, and therefore the problem of poor maintenance convenience in the prior art is solved.
Description
Technical Field
The invention relates to the technical field of photovoltaic power generation, in particular to a photovoltaic power generation system and a photovoltaic inverter.
Background
As shown in fig. 1, a dc side of a conventional photovoltaic power station system based on a centralized inverter generally consists of a combiner box 101, a dc distribution cabinet 102 and a dc side of a photovoltaic inverter 103; the ac side of the pv inverter 103 is further connected to the grid via a transformer.
In order to reduce the system cost, in the current photovoltaic power generation system, the dc side of the photovoltaic inverter 201 is basically designed as a multi-branch circuit (integrated with the function of a dc distribution cabinet), as shown in fig. 2, each branch circuit corresponds to one dc combiner box 202; however, since each dc combiner box 202 needs to be manually operated, and the distance between the photovoltaic inverter 201 and the dc combiner box 202 corresponding to each branch is relatively long, it is troublesome to operate the dc combiner box during maintenance.
Disclosure of Invention
The invention provides a photovoltaic power generation system and a photovoltaic inverter, and aims to solve the problem of poor maintenance convenience in the prior art.
In order to achieve the purpose, the technical scheme provided by the application is as follows:
a photovoltaic inverter comprising: the controller, at least one inversion unit, a plurality of direct current main switches, a plurality of confluence branch fuses and a plurality of maintenance switches; wherein:
one end of each maintenance switch is used as a positive electrode of a direct-current input end of the photovoltaic inverter and is connected with a positive electrode of a corresponding bus branch; the junction branch comprises a plurality of photovoltaic group strings which realize junction output by plugging and unplugging the wiring terminals;
the other end of each maintenance switch is connected with the positive input end of the corresponding direct current main switch through a corresponding confluence branch fuse;
the negative input end of each direct current main switch is used as the negative electrodes of a plurality of direct current input ends of the photovoltaic inverter and is connected with the respective positive input ends of the direct current main switches in a one-to-one correspondence mode through the conflux branch fuse and the negative electrodes of a plurality of conflux branches connected with the maintenance switch;
the positive output end of each direct current main switch and the positive electrode of the direct current side of each inversion unit are connected with a direct current positive bus;
the negative output end of each direct current main switch and the negative electrode of the direct current side of each inversion unit are connected with a direct current negative bus;
the controller is respectively connected with the control end of the direct current main switch and the control end of the inversion unit and is used for controlling the direct current main switch to be in a closed state in a normal grid-connected operation mode and under the condition that the maintenance switch is in the closed state; and controlling the direct current main switch to be in an off state before the machine is shut down and the maintenance switch is in the off state.
Specifically, the number of the direct current main switches is M, the number of the confluence branch fuses and the number of the maintenance switches are both nxm, and both N and M are positive integers;
and the positive input end of each direct current main switch is connected with the N corresponding confluence branch fuses.
Preferably, the method further comprises the following steps: an insulation resistance monitoring unit and a negative grounding kit;
the insulation impedance monitoring unit is respectively connected with the direct current positive bus, the direct current negative bus and the ground;
the negative grounding external member is respectively connected with the direct current negative bus and the ground; the negative grounding kit includes: a negative ground fuse;
the controller is also connected with the output end of the insulation impedance monitoring unit and the control end of the negative grounding external member; the controller is also used for controlling the direct-current negative bus to realize grounding through the negative grounding external member in a normal grid-connected operation mode and under the condition that the maintenance switch is in a closed state; in a normal standby mode, the negative grounding kit is controlled to be disconnected, and the insulation resistance level of the direct current positive bus and the direct current negative bus is monitored through the insulation resistance monitoring unit; and when the negative grounding fuse is fused due to grounding or insulation reduction of the direct current positive bus, stopping the machine and controlling the direct current main switch to be in an off state.
Preferably, the negative grounding kit further comprises: a negative ground switch;
the first end of the negative grounding switch is connected with the direct current negative bus;
the second end of the negative grounding switch is grounded through the negative grounding fuse;
the control end of the negative grounding switch is connected with the controller; under a normal grid-connected operation mode, the negative grounding switch is in a closed state according to the control of the controller;
the controller is further configured to: and in a normal standby mode, the negative grounding switch is controlled to be switched off, and the insulation resistance level of the direct current positive bus and the direct current negative bus is monitored through the insulation resistance monitoring unit.
Preferably, the method further comprises the following steps: m maintenance grounding kits;
the negative input end of each direct current main switch is grounded through one maintenance grounding kit;
the controller is further connected with a control end of the maintenance grounding kit and used for controlling a negative input end of the direct current main switch to realize grounding through the corresponding maintenance grounding kit when the negative grounding fuse is fused and the direct current main switch is in a closed state or after the direct current main switch is disconnected due to faults or maintenance requirements.
Preferably, the maintenance grounding kit comprises: maintaining the grounding switch and the grounding impedance;
the first end of the maintenance grounding switch is connected with the negative electrode input end of the corresponding direct current main switch;
the second end of the maintenance grounding switch is grounded through the maintenance grounding impedance;
the control end of the maintenance grounding switch is connected with the controller; under a normal grid-connected operation mode, the maintenance grounding switch is in a disconnected state according to the control of the controller;
the controller is configured to control the negative input terminal of the dc main switch to be grounded through the corresponding maintenance grounding kit, and specifically configured to: and controlling the maintenance grounding switch to be in a closed state.
Optionally, the maintenance grounding impedance is a resistor.
Optionally, the maintenance switch is a DC20 type switch.
Optionally, the N maintenance switches connected to the same dc main switch through the bus branch fuse are a multipole switch.
A photovoltaic power generation system, comprising: a plurality of bus branches, and a photovoltaic inverter as described in any of the above;
the junction branch comprises a plurality of photovoltaic group strings which realize junction output by plugging and unplugging the wiring terminals;
and a group of serial branch protection fuses are integrated in the plug wiring terminals.
According to the photovoltaic inverter provided by the invention, the maintenance switch in the photovoltaic inverter is combined with the plug-pull wiring terminal connected with the input end, so that a junction box in the prior art is replaced, and the junction input of a plurality of photovoltaic group strings can be realized; the function of the direct-current power distribution cabinet is realized through the confluence branch fuse and the direct-current main switch; therefore, compared with the prior art, the photovoltaic inverter has the advantages that the system integration level is improved, and the implementation cost is reduced. In a normal grid-connected operation mode and when the maintenance switch is in a closed state, the controller controls the direct-current main switch to be in a closed state so as to ensure that the photovoltaic inverter can be normally connected to the grid; before the machine is shut down and the maintenance switch is in a disconnected state, the controller controls the direct current main switch to be in the disconnected state so that the fuse of the bus branch can be maintained; when accomplishing above-mentioned control, need not operating personnel and make a round trip to operate between photovoltaic inverter and a plurality of distance farther collection flow box, and then avoided among the prior art to maintain the poor problem of convenience.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of a photovoltaic power generation system provided by the prior art;
FIG. 2 is a schematic diagram of another photovoltaic power generation system provided by the prior art;
FIG. 3 is a schematic structural diagram of a photovoltaic power generation system provided by an embodiment of the invention;
fig. 4 is a schematic structural diagram of a plug terminal provided in an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The invention provides a photovoltaic inverter, which aims to solve the problem of poor maintenance convenience in the prior art.
Referring to fig. 3, the photovoltaic inverter includes: a controller (not shown), at least one Inverter unit (such as the Inverter # 1 and the Inverter # 2 shown in fig. 3), M direct current main switches (such as the Load Switch1, the Load Switch 2 and the Load Switch3 shown in fig. 3), N × M bus branch fuses (such as the Fuse 1-7, the Fuse 8-14 and the Fuse 15-21 shown in fig. 3), N × M maintenance switches (such as the 8P Switch Disconnect 1, the Disconnect Switch 2 and the Disconnect Switch3 shown in fig. 3), an insulation resistance monitoring unit ISO and a negative ground kit GFDI, where N and M are positive integers; wherein:
the Positive electrode of the direct current side of each inversion unit and the Positive output ends of the M direct current main switches are connected with a direct current Positive Bus; and the Negative electrode of the direct current side of each inversion unit and the Negative electrode output ends of the M direct current main switches are connected with a Negative direct current Bus.
The direct-current Positive Bus and the direct-current Negative Bus are grounded through an insulation impedance monitoring unit ISO; and the direct current Negative Bus is grounded through a Negative grounding kit GFDI; the negative grounding kit GFDI includes: a negative ground Fuse 0.
The positive input end of each direct current main switch is connected with one end of each corresponding N confluence branch fuse wires; in fig. 3, taking N ═ 8 as an example, the positive input terminal of the dc main Switch Load Switch1 is connected to one end of the 8 bus Fuse fuses 1-7 corresponding to itself, the positive input terminal of the dc main Switch Load Switch 2 is connected to one end of the 8 bus Fuse fuses 8-14 corresponding to itself, and the positive input terminal of the dc main Switch Load Switch3 is connected to one end of the 8 bus Fuse fuses 15-21 corresponding to itself.
The other end of each bus branch fuse is connected with one end of a corresponding maintenance switch; in practical applications, the maintenance Switch may be a DC20 type Switch which does not have a load breaking capability and is manually controlled, and since the load breaking capability is not required, N maintenance switches connected to the same DC main Switch through the bus branch fuse may be implemented by using one multi-pole Switch, thereby saving space, and fig. 3 illustrates 8P switches (Disconnect Switch1, Disconnect Switch 2, and Disconnect Switch 3).
The other end of each maintenance switch is used as a Positive electrode of a direct current input end of the photovoltaic inverter and is connected with a Positive electrode Positive of a corresponding confluence branch; each bus branch comprises a plurality of photovoltaic group strings PV String for realizing bus output by plugging and unplugging the wiring terminals; the structure of this plug binding post is shown in fig. 4, possesses the function of converging to, use with the inside maintenance switch cooperation of this photovoltaic inverter, and then realized the replacement to the collection flow box among the traditional scheme.
The Negative input end of each direct current main switch is used as the Negative electrodes of N direct current input ends of the photovoltaic inverter and is correspondingly connected with the Negative electrodes Negative of N confluence branches connected with the respective positive input ends through confluence branch fuses and the maintenance switches; as shown in fig. 3: the cathodes of the 8 bus branches connected with the Disconnect Switch1 are connected with the cathode input end of the Load Switch 1; the cathodes of the 8 bus branches connected with the Disconnect Switch 2 are connected with the cathode input end of the LoadSwitch 2; the cathodes of the 8 bus branches connected with the Disconnect Switch3 are connected with the cathode input end of the Load Switch 3; the connection forms of other multi-pole switches and the connection forms under the condition that N is other values can be obtained by analogy, and the description is omitted here.
The controller is respectively connected with the output end of the insulation impedance monitoring unit ISO, the control end of the negative grounding kit GFDI, the control end of the direct current main switch and the control end of the inversion unit.
In practical application, the number of the fuse of the bus branch, the number of the maintenance switches, the number of the direct current main switches and the number of the maintenance grounding kits are not limited by the condition shown in fig. 3; the values of M and N are mainly set based on different capacities of the photovoltaic inverter and the like, and other combination conditions can be provided according to practical application environments, and the values are within the protection range of the application.
The specific working principle is as follows:
in a normal grid-connected operation mode and under the condition that the maintenance switch is in a closed state through manual control, the controller controls the direct-current main switch to be in the closed state so as to ensure that the photovoltaic inverter can be normally connected to the grid; meanwhile, the controller also controls the direct current Negative Bus to realize grounding through a Negative grounding kit GFDI (ground connection interface), so that the controller is compatible with a Negative grounding function and plays a role in preventing a panel from generating a PID (Potential Induced Degradation) effect; and because the negative grounding Fuse FUSE0 is grounded, when the insulation resistance of the Positive direct current Bus Positive Bus to the ground is reduced (such as cable sheath breaking), the negative grounding Fuse FUSE0 can be fused due to increased leakage current, so that the problem of reduction of the insulation resistance of the Positive direct current Bus Positive Bus to the ground is reflected, and the corresponding problem can be maintained in time.
In a normal standby mode, for example, before the startup and grid connection are carried out every morning, the controller can control the Negative grounding kit GFDI to be disconnected, and the insulation resistance levels of the Positive direct current Bus Positive Bus and the Negative direct current Bus Negative Bus are monitored through the insulation resistance monitoring unit ISO, so that the photovoltaic inverter is compatible with an insulation monitoring function.
Since the maintenance switch strictly prohibits the on-load disconnection, the controller needs to control the dc main switch to be in the disconnected state before the shutdown and the maintenance switch is manually disconnected, so that the bus branch fuse can be maintained.
It is worth noting that in the solution shown in fig. 2, the negative grounding Fuse0 is always connected to the negative terminal of each bus branch, and a specific solution for the damage maintenance of the grounding Fuse0 in the prior art is lacking. In the photovoltaic inverter provided by this embodiment, after the negative grounding Fuse0 is fused due to the grounding or insulation reduction of the dc Positive Bus, the controller will stop and control the dc main switch to be in the off state, and since the dc main switch disconnects the negative pre-stage input, the safety when the negative grounding Fuse0 is replaced can be ensured, so that the negative grounding Fuse0 can be maintained.
In summary, the photovoltaic inverter provided in this embodiment replaces the junction box in the prior art by combining the maintenance switch inside the photovoltaic inverter with the plug-in connection terminal connected to the input terminal, so as to realize the junction input of the plurality of photovoltaic String PV strings; the function of the direct-current power distribution cabinet is realized through the confluence branch fuse and the direct-current main switch; therefore, compared with the prior art, the photovoltaic inverter has the advantages that the system integration level is improved, and the implementation cost is reduced. Moreover, the control can be completed in the photovoltaic inverter without back-and-forth operation between the photovoltaic inverter and a plurality of combiner boxes which are far away from each other, so that the problem of poor maintenance convenience in the prior art is solved.
Another embodiment of the present invention further provides a specific photovoltaic inverter, and based on the above embodiment, the negative grounding kit GFDI, as shown in fig. 3, further includes: a negative ground switch K0;
the first end of the Negative grounding switch K0 is connected with a Negative direct current Bus;
the second end of the negative grounding switch K0 is grounded through a negative grounding Fuse 0;
the control end of the negative grounding switch K0 is connected with the controller; in the normal grid-connected operation mode, the negative grounding switch K0 is in a closed state according to the control of the controller.
At this time, the controller within the photovoltaic inverter is further configured to:
when grounding or insulation reduction occurs to the direct current Positive Bus, and the negative grounding Fuse FUSE0 is fused, the controller stops the machine and controls the direct current main switch and the negative grounding switch K0 to be in a disconnected state, and as the direct current main switch and the negative grounding switch K0 disconnect the negative pre-stage input, the safety during replacement of the negative grounding Fuse FUSE0 can be ensured, and the negative grounding Fuse FUSE0 can be maintained;
in a normal standby mode, for example, before starting and grid-connecting in the morning, the Negative grounding switch K0 is controlled to be switched off, and the insulation resistance levels of the direct-current Positive Bus and the direct-current Negative Bus are monitored through the insulation resistance monitoring unit ISO, so that the photovoltaic inverter is compatible with an insulation monitoring function.
The rest of the structure and the principle are the same as those of the above embodiments, and are not described in detail here.
With the solution shown in fig. 2, when the negative ground Fuse FUSE0 is fused, if maintenance is to be performed, the problem of negative floating electrification is also encountered, and the safety of maintenance work is low. Therefore, another embodiment of the present invention further provides a specific photovoltaic inverter, and based on the above embodiment, preferably, the photovoltaic inverter further includes: m maintenance grounding kits;
the negative input end of each direct current main switch is grounded through a maintenance grounding external member;
the controller in the photovoltaic inverter is also connected with a control end of the maintenance grounding external member, so that when the negative grounding fuse0 is fused and the direct current main switch is not disconnected, or after the direct current main switch is disconnected due to faults or maintenance requirements, the negative input end of the direct current main switch is controlled to realize grounding through the corresponding maintenance grounding external member, and the safety problem of negative suspension electrification is solved.
Optionally, the maintenance grounding kit comprises: maintenance ground switches (e.g., K1, K2, and K3 shown in fig. 3) and maintenance ground impedances (e.g., R1, R2, and R3 shown in fig. 3);
the first end of the maintenance grounding switch is connected with the negative input end of the corresponding direct current main switch;
the second end of the maintenance grounding switch is grounded through the maintenance grounding impedance;
the control end of the maintenance grounding switch is connected with the controller; and under the normal grid-connected operation mode, the maintenance grounding switch is in a disconnected state according to the control of the controller.
Referring to fig. 3, taking M ═ 3 as an example for illustration, a first end of the maintenance ground switch K1 is connected to a negative input end of the dc main switch LoadSwitch 1, and a second end of the maintenance ground switch K1 is grounded through a maintenance ground impedance R1; the first end of a maintenance grounding Switch K2 is connected with the negative input end of a direct current main Switch Load Switch 2, and the second end of a maintenance grounding Switch K2 is grounded through a maintenance grounding impedance R2; the first end of a maintenance grounding Switch K3 is connected with the negative input end of a direct current main Switch Load Switch3, and the second end of a maintenance grounding Switch K3 is grounded through a maintenance grounding impedance R3; the specific implementation form of other maintenance grounding external members and the connection form when M is other values can be obtained by analogy, and are not described in detail herein.
At this moment, when the controller in this photovoltaic inverter is used for controlling the negative pole input of direct current main switch to ground through corresponding maintenance ground external member, specifically be used for: and controlling and maintaining the grounding switch to be in a closed state.
Optionally, the maintenance grounding impedance is a resistor; in practical application, a series-parallel connection form of the resistor may also be adopted, and the resistor is not specifically limited herein and is within the protection scope of the present application.
The rest of the structure and the principle are the same as those of the above embodiments, and are not described in detail here.
Another embodiment of the present invention further provides a photovoltaic power generation system, as shown in fig. 3, including: n × M bus branches, and, as in any of the above embodiments, the photovoltaic inverter, N and M being positive integers;
the junction branch comprises a plurality of photovoltaic group strings PV String which realize junction output by plugging and unplugging the wiring terminals;
and a group of serial branch protection fuses are integrated in the plug-in wiring terminals.
Each photovoltaic String PV String is connected to the dc input of the photovoltaic inverter via a corresponding dc cable and a plug-in connection terminal.
As shown in fig. 3, the photovoltaic inverter includes: a controller (not shown), a plurality of Inverter units (such as the Inverter # 1 and the Inverter # 2 shown in fig. 3), M direct current main switches (such as the Load Switch1, the Load Switch 2 and the Load Switch3 shown in fig. 3), N × M bus branch fuses (such as the Fuse 1-7, the Fuse 8-14 and the Fuse 15-21 shown in fig. 3), N × M maintenance switches (such as the 8P Switch Disconnect 1, the Disconnect Switch 2 and the Disconnect Switch3 shown in fig. 3), an insulation resistance monitoring unit ISO and a negative grounding kit GFDI, where N and M are positive integers; wherein:
the Positive electrode of the direct current side of each inversion unit and the Positive output ends of the M direct current main switches are connected with a direct current Positive Bus; and the Negative electrode of the direct current side of each inversion unit and the Negative electrode output ends of the M direct current main switches are connected with a Negative direct current Bus.
The direct-current Positive Bus and the direct-current Negative Bus are grounded through an insulation impedance monitoring unit ISO; and the direct current Negative Bus is grounded through a Negative grounding kit GFDI; the negative grounding kit GFDI includes: a negative ground Fuse 0.
And the positive input end of each direct current main switch is connected with one end of each corresponding N bus branch fuse wires.
The other end of each bus branch fuse is connected with one end of a corresponding maintenance switch; in practical application, the maintenance switch can adopt a DC20 type switch which does not have load breaking capacity and is manually controlled, and because the load breaking capacity is not needed, N maintenance switches connected with the same direct current main switch through the bus branch fuse wire can be realized by adopting a multi-pole switch, thereby saving space.
The other end of each maintenance switch is used as a Positive electrode of a direct current input end of the photovoltaic inverter and is connected with a Positive electrode Positive of a corresponding confluence branch; each bus branch comprises a plurality of photovoltaic group strings PV String for realizing bus output by plugging and unplugging the wiring terminals; the structure of this plug binding post is shown in fig. 4, possesses the function of converging to, use with the inside maintenance switch cooperation of this photovoltaic inverter, and then realized the replacement to the collection flow box among the traditional scheme.
The Negative input end of each direct current main switch is used as the Negative electrodes of N direct current input ends of the photovoltaic inverter and is correspondingly connected with the Negative electrodes Negative of N confluence branches connected with the respective positive input ends through confluence branch fuses and the maintenance switches; as shown in fig. 3: the cathodes of the 8 bus branches connected with the Disconnect Switch1 are connected with the cathode input end of the Load Switch 1; the cathodes of the 8 bus branches connected with the Disconnect Switch 2 are connected with the cathode input end of the LoadSwitch 2; the cathodes of the 8 bus branches connected with the Disconnect Switch3 are connected with the cathode input end of the Load Switch 3; the connection forms of other multi-pole switches and the connection forms under the condition that N is other values can be obtained by analogy, and the description is omitted here.
The controller is respectively connected with the output end of the insulation impedance monitoring unit ISO, the control end of the negative grounding kit GFDI, the control end of the direct current main switch and the control end of the inversion unit.
Optionally, the negative grounding kit GFDI, as shown in fig. 3, further includes: a negative ground switch K0;
the first end of the Negative grounding switch K0 is connected with a Negative direct current Bus;
the second end of the negative grounding switch K0 is grounded through a negative grounding Fuse 0;
the control end of the negative grounding switch K0 is connected with the controller; in the normal grid-connected operation mode, the negative grounding switch K0 is in a closed state according to the control of the controller.
Optionally, the photovoltaic inverter further includes: m maintenance grounding kits;
the negative input end of each direct current main switch is grounded through a maintenance grounding external member;
the controller in the photovoltaic inverter is also connected with a control end of the maintenance grounding external member, so that when the negative grounding fuse0 is fused and the direct current main switch is not disconnected, or after the direct current main switch is disconnected due to faults or maintenance requirements, the negative input end of the direct current main switch is controlled to realize grounding through the corresponding maintenance grounding external member, and the safety problem that the negative electrode is suspended and electrified under the condition that the negative grounding fuse is damaged is solved.
Optionally, the maintenance grounding kit comprises: maintenance ground switches (e.g., K1, K2, and K3 shown in fig. 3) and maintenance ground impedances (e.g., R1, R2, and R3 shown in fig. 3);
the first end of the maintenance grounding switch is connected with the negative input end of the corresponding direct current main switch;
the second end of the maintenance grounding switch is grounded through the maintenance grounding impedance;
the control end of the maintenance grounding switch is connected with the controller; and under the normal grid-connected operation mode, the maintenance grounding switch is in a disconnected state according to the control of the controller.
Optionally, the service ground impedance is a resistor.
The working principle of the photovoltaic inverter is the same as that of the above embodiments, and the details are not repeated here.
According to the photovoltaic power generation system provided by the embodiment, the maintenance switch of the direct-current part of the photovoltaic inverter is integrated with the confluence branch, and the plugging and pulling of the wiring terminal are matched, so that a confluence box and a direct-current power distribution cabinet in the traditional scheme can be omitted, the integration level of the system is improved, and the cost of the system is further reduced; meanwhile, the insulation monitoring and cathode grounding functions can be compatible, the safety problems of the cathode grounding fuse wire maintenance and the cathode suspension electrification under the fuse wire damage condition are solved, the maintenance convenience and safety are fully considered, and the popularization is facilitated.
The embodiments of the invention are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments can be referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner. Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make numerous possible variations and modifications to the present teachings, or modify equivalent embodiments to equivalent variations, without departing from the scope of the present teachings, using the methods and techniques disclosed above. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the scope of the protection of the technical solution of the present invention, unless the contents of the technical solution of the present invention are departed.
Claims (10)
1. A photovoltaic inverter, comprising: the controller, at least one inversion unit, a plurality of direct current main switches, a plurality of confluence branch fuses and a plurality of maintenance switches; wherein:
one end of each maintenance switch is used as a positive electrode of a direct-current input end of the photovoltaic inverter and is connected with a positive electrode of a corresponding bus branch; the junction branch comprises a plurality of photovoltaic group strings which realize junction output by plugging and unplugging the wiring terminals;
the other end of each maintenance switch is connected with the positive input end of the corresponding direct current main switch through a corresponding confluence branch fuse;
the negative input end of each direct current main switch is used as the negative electrodes of a plurality of direct current input ends of the photovoltaic inverter and is connected with the respective positive input ends of the direct current main switches in a one-to-one correspondence mode through the conflux branch fuse and the negative electrodes of a plurality of conflux branches connected with the maintenance switch;
the positive output end of each direct current main switch and the positive electrode of the direct current side of each inversion unit are connected with a direct current positive bus;
the negative output end of each direct current main switch and the negative electrode of the direct current side of each inversion unit are connected with a direct current negative bus;
the controller is respectively connected with the control end of the direct current main switch and the control end of the inversion unit and is used for controlling the direct current main switch to be in a closed state in a normal grid-connected operation mode and under the condition that the maintenance switch is in the closed state; and controlling the direct current main switch to be in an off state before the machine is shut down and the maintenance switch is in the off state.
2. The photovoltaic inverter of claim 1, wherein the number of the main dc switches is M, the number of the bus branch fuses and the number of the maintenance switches are both nxm, and both N and M are positive integers;
and the positive input end of each direct current main switch is connected with the N corresponding confluence branch fuses.
3. The photovoltaic inverter of claim 2, further comprising: an insulation resistance monitoring unit and a negative grounding kit;
the insulation impedance monitoring unit is respectively connected with the direct current positive bus, the direct current negative bus and the ground;
the negative grounding external member is respectively connected with the direct current negative bus and the ground; the negative grounding kit includes: a negative ground fuse;
the controller is also connected with the output end of the insulation impedance monitoring unit and the control end of the negative grounding external member; the controller is also used for controlling the direct-current negative bus to realize grounding through the negative grounding external member in a normal grid-connected operation mode and under the condition that the maintenance switch is in a closed state; in a normal standby mode, the negative grounding kit is controlled to be disconnected, and the insulation resistance level of the direct current positive bus and the direct current negative bus is monitored through the insulation resistance monitoring unit; and when the negative grounding fuse is fused due to grounding or insulation reduction of the direct current positive bus, stopping the machine and controlling the direct current main switch to be in an off state.
4. The photovoltaic inverter of claim 3, wherein the negative grounding kit further comprises: a negative ground switch;
the first end of the negative grounding switch is connected with the direct current negative bus;
the second end of the negative grounding switch is grounded through the negative grounding fuse;
the control end of the negative grounding switch is connected with the controller; under a normal grid-connected operation mode, the negative grounding switch is in a closed state according to the control of the controller;
the controller is further configured to: and in a normal standby mode, the negative grounding switch is controlled to be switched off, and the insulation resistance level of the direct current positive bus and the direct current negative bus is monitored through the insulation resistance monitoring unit.
5. The photovoltaic inverter of claim 4, further comprising: m maintenance grounding kits;
the negative input end of each direct current main switch is grounded through one maintenance grounding kit;
the controller is further connected with a control end of the maintenance grounding kit and used for controlling a negative input end of the direct current main switch to realize grounding through the corresponding maintenance grounding kit when the negative grounding fuse is fused and the direct current main switch is in a closed state or after the direct current main switch is disconnected due to faults or maintenance requirements.
6. The photovoltaic inverter of claim 5, wherein the maintenance grounding kit comprises: maintaining the grounding switch and the grounding impedance;
the first end of the maintenance grounding switch is connected with the negative electrode input end of the corresponding direct current main switch;
the second end of the maintenance grounding switch is grounded through the maintenance grounding impedance;
the control end of the maintenance grounding switch is connected with the controller; under a normal grid-connected operation mode, the maintenance grounding switch is in a disconnected state according to the control of the controller;
the controller is configured to control the negative input terminal of the dc main switch to be grounded through the corresponding maintenance grounding kit, and specifically configured to: and controlling the maintenance grounding switch to be in a closed state.
7. The photovoltaic inverter of claim 6, wherein the service ground impedance is a resistor.
8. Photovoltaic inverter according to any of claims 1-7, characterized in that the maintenance switch is a DC20 type switch.
9. The pv inverter according to any one of claims 2-7, wherein the N maintenance switches connected to the same dc main switch via the bus branch fuse are a multipole switch.
10. A photovoltaic power generation system, comprising: a plurality of bus branches, and a photovoltaic inverter as claimed in any one of claims 1 to 9;
the junction branch comprises a plurality of photovoltaic group strings which realize junction output by plugging and unplugging the wiring terminals;
and a group of serial branch protection fuses are integrated in the plug wiring terminals.
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