CN104917200B - Grid-connected photovoltaic system and its application method - Google Patents
Grid-connected photovoltaic system and its application method Download PDFInfo
- Publication number
- CN104917200B CN104917200B CN201510290062.5A CN201510290062A CN104917200B CN 104917200 B CN104917200 B CN 104917200B CN 201510290062 A CN201510290062 A CN 201510290062A CN 104917200 B CN104917200 B CN 104917200B
- Authority
- CN
- China
- Prior art keywords
- voltage
- ground
- grid
- inverting circuit
- phase inverting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- 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
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
Abstract
The invention discloses a kind of grid-connected photovoltaic system and its application methods, belong to technical field of photovoltaic power generation.The system includes：Three-phase inverting circuit, adjustable voltage unit and isolating transformer, three-phase inverting circuit include control unit, control unit connection adjustable voltage unit；Three-phase inverting circuit input terminal is connect with photovoltaic battery panel, and three-phase inverting circuit output terminal is connect with isolating transformer one end, and the isolating transformer other end is connect with power grid；Control unit is used for three-phase inverting circuit output common mode voltage signal sampling over the ground, and is detected and exported whether common-mode voltage over the ground is more than preset value, and when output, common-mode voltage is more than preset value over the ground, generates and adjusts signal, and sends adjustment signal to adjustable voltage unit；According to output of the adjustment signal to three-phase inverting circuit, common-mode voltage is adjusted adjustable voltage unit over the ground.The present invention solves the problems, such as that grid-connected photovoltaic system safety in operation is relatively low, the effect for improving safety is realized, for parallel network power generation.
Description
Technical field
The present invention relates to technical field of photovoltaic power generation, more particularly to a kind of grid-connected photovoltaic system and its application method.
Background technology
Grid-connected photovoltaic system is the electricity generation system that electric energy is directly converted solar energy into using solar cell.In reality
In the application of border, in order to ensure the safe operation of grid-connected photovoltaic system, need that grid-connected photovoltaic system insulate strong
Degree detection.
Existing grid-connected photovoltaic system 103 is as shown in Figure 1, mainly include three-phase inverting circuit 1031, positioned at three-phase
The leakage current sensor 1032 of the exchange side (output terminal of three-phase inverting circuit) of inverter circuit 1031, isolating transformer 1033,
And in the three-phase inverting circuit 1031 and with the control unit 1034 of leakage current sensor 1032.Grid-connected photovoltaic system
Power grid 102 is sent into after 103 converting direct-current power into alternating-current power for generating photovoltaic battery panel 101.When carrying out insulation impedance detection,
Dielectric strength detection typically is carried out to the DC side of three-phase inverting circuit (input terminal of three-phase inverting circuit), for three contraries
The exchange side for becoming circuit is then to ensure its dielectric strength by the design selection of cable.Meanwhile when the direct current of three-phase inverting circuit
When side shorted to earth or smaller impedance, very big leakage current can be generated between DC side and the earth, and flow to three-phase inverting circuit
Exchange side, at this point, control unit detects that the leakage current that leakage current sensor measures is more than preset value, then control grid-connected
Electricity generation system carries out troubleshooting.
Grid-connected photovoltaic system is in actual moving process, and common-mode voltage may exceed wanting for dielectric strength over the ground for output
It asks, there are the risk of failure of insulation, and the dielectric strength of grid-connected photovoltaic system usually not exchange side detects, and only relies on line
The design selection of cable ensures that the dielectric strength of exchange side is can not to meet the long-term safety of grid-connected photovoltaic system to run
It is required that, meanwhile, leakage current sensor belongs to a kind of passive protection to the protection of system, can not identify in advance and dissolve operation wind
Danger, can not fundamentally ensure the safe operation of grid-connected photovoltaic system, therefore, the safety of grid-connected photovoltaic system operation
Property is relatively low.
Invention content
In order to solve the problems, such as that the safety of grid-connected photovoltaic system operation is relatively low, the present invention provides a kind of photovoltaic simultaneously
Net electricity generation system and its application method.The technical solution is as follows：
In a first aspect, providing a kind of grid-connected photovoltaic system, the grid-connected photovoltaic system includes：Three-phase inversion
Circuit, adjustable voltage unit and isolating transformer, the three-phase inverting circuit include control unit, described control unit connection institute
State adjustable voltage unit；
The input terminal of the three-phase inverting circuit is connect with photovoltaic battery panel, the output terminal of the three-phase inverting circuit and institute
One end connection of isolating transformer is stated, the other end of the isolating transformer is connect with power grid；
Described control unit is used for：To the output of the three-phase inverting circuit, common mode voltage signal samples over the ground, and
Detecting the output, whether common-mode voltage is more than preset value over the ground, and when the output, common-mode voltage is more than the preset value over the ground
When, generation adjustment signal, and send the adjustment signal to the adjustable voltage unit；
The adjustable voltage unit is used for：According to the adjustment signal to the output of three-phase inverting circuit common mode over the ground
Voltage is adjusted.
With reference to first aspect, can be in realization mode at the first, change is isolated with described in one end of the adjustable voltage unit
One end connection of depressor, other end ground connection, one end of the isolating transformer connect one end of the three-phase inverting circuit；Or
Person, one end of the adjustable voltage unit are connect with the output terminal of the three-phase inverting circuit, other end ground connection.
Mode can be realized with reference to the first, and in second of achievable mode, the adjustable voltage unit includes：Straight-adjustable
Stream source and voltage coupler；
The one end in the adjustable DC source is connect by the voltage coupler with one end of the isolating transformer, described
The other end ground connection in adjustable DC source, one end of the isolating transformer connect one end of the three-phase inverting circuit；Alternatively, institute
The one end for stating adjustable DC source is connect by the voltage coupler with the output terminal of the three-phase inverting circuit, the straight-adjustable
The other end ground connection in stream source.
, can be in realization mode at the third with reference to second of achievable mode, the voltage coupler includes capacitance, resistance
At least one of with inductance.
Mode can be realized with reference to the first, and in the 4th kind of achievable mode, the three-phase inverting circuit further includes inversion
Main circuit and inductance；
Described control unit is connect with the inverter main circuit；
The inverter main circuit is two-stage conversion circuit or level-one conversion circuit.
With reference to the 4th kind of achievable mode, in the 5th kind of achievable mode,
The two-stage conversion circuit includes DC-DC power supply and direct current turns AC power；
The level-one conversion circuit turns AC power including direct current.
With reference to the 4th kind of achievable mode, in the 6th kind of achievable mode,
Capacitance is connected between the two-stage conversion circuit.
Second aspect, provides a kind of application method of grid-connected photovoltaic system, and the grid-connected photovoltaic system is
First aspect any one can be described in realization mode grid-connected photovoltaic system, the grid-connected photovoltaic system includes three-phase
Inverter circuit, the method includes：
To the output of the three-phase inverting circuit, common mode voltage signal samples over the ground, and detects the output over the ground altogether
Whether mode voltage is more than preset value, when common-mode voltage is more than the preset value over the ground for the output, generation adjustment signal；
According to output of the adjustment signal to the three-phase inverting circuit, common-mode voltage is adjusted over the ground.
The present invention provides a kind of grid-connected photovoltaic system and its application method, by control unit to three-phase inversion electricity
Common mode voltage signal is sampled over the ground for the output on road, and is detected and exported whether common-mode voltage over the ground is more than preset value, works as output
When common-mode voltage is more than preset value over the ground, generation adjustment signal, and send adjustment signal to adjustable voltage unit；Again by adjustable
According to output of the adjustment signal to three-phase inverting circuit, common-mode voltage is adjusted voltage cell over the ground, is completed to exchange side
Common-mode voltage carries out actively monitoring and adjustment over the ground for output, so as to avoid grid-connected photovoltaic system in the process of running, due to
The risk of common-mode voltage failure of insulation of exchange side caused by the requirement of dielectric strength over the ground is exported, this improves
The safety of grid-connected photovoltaic system operation.
It should be understood that above general description and following detailed description are only exemplary and explanatory, not
It can the limitation present invention.
Description of the drawings
To describe the technical solutions in the embodiments of the present invention more clearly, make required in being described below to embodiment
Attached drawing is briefly described, it should be apparent that, the accompanying drawings in the following description is only some embodiments of the present invention, for
For those of ordinary skill in the art, without creative efforts, other are can also be obtained according to these attached drawings
Attached drawing.
Fig. 1 is a kind of structure diagram of existing grid-connected photovoltaic system provided in an embodiment of the present invention；
Fig. 2 is a kind of structure diagram of grid-connected photovoltaic system provided in an embodiment of the present invention；
Fig. 3 is a kind of structure diagram of grid-connected photovoltaic system with N lines provided in an embodiment of the present invention；
Fig. 4 is the structure diagram of another grid-connected photovoltaic system with N lines provided in an embodiment of the present invention；
Fig. 5 is the structure diagram of another grid-connected photovoltaic system with N lines provided in an embodiment of the present invention；
Fig. 6 is the structure diagram of another grid-connected photovoltaic system with N lines provided in an embodiment of the present invention；
Fig. 7 is a kind of structure diagram of grid-connected photovoltaic system without N lines provided in an embodiment of the present invention；
Fig. 8 is the structure diagram of another grid-connected photovoltaic system without N lines provided in an embodiment of the present invention；
Fig. 9 be it is provided in an embodiment of the present invention another without the grid-connected photovoltaic system of N lines structure diagram；
Figure 10 be it is provided in an embodiment of the present invention another without the grid-connected photovoltaic system of N lines structural representation
Figure；
Figure 11 is a kind of flow chart of the application method of grid-connected photovoltaic system provided in an embodiment of the present invention.
Pass through above-mentioned attached drawing, it has been shown that the specific embodiment of the present invention will be hereinafter described in more detail.These attached drawings
It is not intended to limit the range of present inventive concept by any mode with word description, but is by reference to specific embodiment
Those skilled in the art illustrate idea of the invention.
Specific embodiment
To make the object, technical solutions and advantages of the present invention clearer, below in conjunction with attached drawing to embodiment party of the present invention
Formula is described in further detail.
An embodiment of the present invention provides a kind of grid-connected photovoltaic system, as shown in Fig. 2, the grid-connected photovoltaic system packet
It includes：Three-phase inverting circuit 201, adjustable voltage unit 202 and isolating transformer 204, three-phase inverting circuit 201 include control unit
203, control unit 203 connects adjustable voltage unit 202.
Wherein, the input terminal of three-phase inverting circuit 201 is connect with photovoltaic battery panel 20, the output of three-phase inverting circuit 201
End is connect with one end of isolating transformer 204, and the other end of isolating transformer 204 is connect with power grid 21.
Control unit 203 is used for：To the output of three-phase inverting circuit 201, common mode voltage signal samples over the ground, and examines
Surveying output, whether common-mode voltage is more than preset value over the ground, when common-mode voltage is more than preset value over the ground for output, generation adjustment signal,
And send adjustment signal to adjustable voltage unit 202.
Adjustable voltage unit 202 is used for：According to adjustment signal to the output of three-phase inverting circuit 201 over the ground common-mode voltage into
Row adjustment.It should be noted that adjustable voltage unit 202 is connected with various ways in grid-connected photovoltaic system, Fig. 2 shows
What is gone out is the structure diagram that is connect with one end of isolating transformer 204 of one end of adjustable voltage unit 202, and adjustable voltage list
The other end of member 202 is grounded, and ground terminal is identified with PE in figure.
In conclusion grid-connected photovoltaic system provided in an embodiment of the present invention, by control unit to three-phase inversion electricity
Common mode voltage signal is sampled over the ground for the output on road, and is detected and exported whether common-mode voltage over the ground is more than preset value, works as output
When common-mode voltage is more than preset value over the ground, generation adjustment signal, and send adjustment signal to adjustable voltage unit；Again by adjustable
According to output of the adjustment signal to three-phase inverting circuit, common-mode voltage is adjusted voltage cell over the ground, is completed to exchange side
Common-mode voltage carries out actively monitoring and adjustment over the ground for output, so as to avoid grid-connected photovoltaic system in the process of running, due to
The risk of common-mode voltage failure of insulation of exchange side caused by the requirement of dielectric strength over the ground is exported, this improves
The safety of grid-connected photovoltaic system operation.
Further, one end of adjustable voltage unit and one end of isolating transformer connect, and transformation is isolated in other end ground connection
One end of one end connection three-phase inverting circuit of device；Alternatively, one end of adjustable voltage unit and the output terminal of three-phase inverting circuit
Connection, other end ground connection.
Specifically, adjustable voltage unit includes：Adjustable DC source and voltage coupler；Wherein, the one end in adjustable DC source
It is connected by one end of voltage coupler and isolating transformer, the other end ground connection in adjustable DC source, one end of isolating transformer
Connect one end of three-phase inverting circuit；Alternatively, the one end in adjustable DC source passes through the defeated of voltage coupler and three-phase inverting circuit
Outlet connects, the other end ground connection in adjustable DC source.
Exemplary, voltage coupler can include at least one of capacitance, resistance and inductance.
In addition, three-phase inverting circuit can also include inverter main circuit and inductance, control unit is connect with inverter main circuit,
The inverter main circuit can be two-stage conversion circuit or level-one conversion circuit.
Exemplary, two-stage conversion circuit can include DC-DC power supply and direct current and turn AC power, and a level conversion
Circuit can turn AC power including direct current.
It is exemplary, capacitance can be connected between two-stage conversion circuit.
In conclusion grid-connected photovoltaic system provided in an embodiment of the present invention, by control unit to three-phase inversion electricity
Common mode voltage signal is sampled over the ground for the output on road, and is detected and exported whether common-mode voltage over the ground is more than preset value, works as output
When common-mode voltage is more than preset value over the ground, generation adjustment signal, and send adjustment signal to adjustable voltage unit；Again by adjustable
According to output of the adjustment signal to three-phase inverting circuit, common-mode voltage is adjusted voltage cell over the ground, is completed to three-phase inversion
Common-mode voltage carries out actively monitoring and adjustment over the ground for the output of circuit AC side, so as to which grid-connected photovoltaic system be avoided to run
In the process, the risk of the failure of insulation of exchange side caused by common-mode voltage is beyond the requirement of dielectric strength over the ground due to output,
This improves the safeties of grid-connected photovoltaic system operation.
One end of isolating transformer connection three-phase inverting circuit may carry N lines (zero curve), it is also possible to without N lines.When
When one end of isolating transformer connection three-phase inverting circuit carries N lines, a kind of parallel network power generation provided in an embodiment of the present invention
System, as shown in figure 3, the grid-connected photovoltaic system includes：Three-phase inverting circuit 201, adjustable voltage unit 202, isolation become
Depressor 204, three-phase inverting circuit 201 include control unit 203, and control unit 203 connects adjustable voltage unit 202.
Wherein, the input terminal (PV+ ends and PV- ends) of three-phase inverting circuit 201 is connect, three-phase inversion with photovoltaic battery panel 20
The output terminal of circuit 201 is connect with one end of isolating transformer 204, and the other end of isolating transformer 204 is connect with power grid 21.Tool
Body, as shown in figure 3, three-phase inverting circuit 201 further includes inverter main circuit 2011 and inductance 2012 (i.e. L1, L2 and L3), control
Unit 203 processed is connect with inverter main circuit 2011, and inverter main circuit 2011 is two-stage conversion circuit or level-one conversion circuit.Example
, two-stage conversion circuit can include direct current (English：Direct Current；Referred to as：DC) turn DC power supply and DC delivers stream (English
Text：Alternating Current；Referred to as：AC) power supply, as shown in Figure 3.Level-one conversion circuit can turn AC power supplies including DC.
It is exemplary, capacitance 20111 can be connected between two-stage conversion circuit.DC/DC refers to a fixed DC voltage
It is transformed to variable DC voltage, also referred to as dc chopper.Capacitance is used to inhibit the flip-flop in voltage waveform.
Isolating transformer is used to implement the electrical isolation of photovoltaic battery panel and power grid, improves grid-connected photovoltaic system operation
Safety.
As shown in figure 3, one end of adjustable voltage unit 202 is connect with one end of isolating transformer 204, other end ground connection
(PE), one end of one end connection three-phase inverting circuit 201 of isolating transformer 204.Specifically, as shown in figure 3, adjustable voltage list
Member 202 can include：Adjustable DC DC sources 2021 and voltage coupler 2022 (i.e. C), wherein, the one end in adjustable DC sources 2021
(anode+) is connect by voltage coupler 2022 with one end of isolating transformer 204, and the other end in adjustable DC sources 2021 is (negative
End -) ground connection, one end of one end connection three-phase inverting circuit 201 of isolating transformer 204.
Control unit 203 is used for：To the output of three-phase inverting circuit 201, common mode voltage signal samples over the ground, and examines
Surveying output, whether common-mode voltage is more than preset value over the ground, when common-mode voltage is more than preset value over the ground for output, generation adjustment signal,
And send adjustment signal to adjustable voltage unit 202；Adjustable voltage unit 202 is used for：According to adjustment signal to three-phase inversion electricity
Common-mode voltage is adjusted over the ground for the output on road 201.Specifically, as shown in figure 4, control unit 203 detects three-phase inversion respectively
The a phases of 201 exchange side of circuit to N lines phase voltage VaN, b phase to N lines phase voltage VbN and c phase to N lines phase voltage VcN,
N lines are detected to the voltage VNPE of ground wire PE simultaneously, then can obtain the output of a, b and c tri- with respect to PE common mode over the ground by calculating
Voltage VaPE, VbPE and VcPE：
VaPE=VaN+VNPE；
VbPE=VbN+VNPE；
VcPE=VcN+VNPE.
By detecting the output of a, b and c tri- with respect to PE, whether common-mode voltage is more than preset value to control unit 203 over the ground, can
To judge whether the exchange side outlet line of three-phase inverting circuit meets dielectric strength requirement under current voltage grade.Work as output
When common-mode voltage is more than preset value over the ground, i.e., exchange side outlet line is unsatisfactory for dielectric strength requirement under current voltage grade
When, the generation adjustment signal of control unit 203, and send adjustment signal to adjustable voltage unit 202.
The output voltage in the adjustable DC sources 2021 of adjustable voltage unit 202 is adjustable, can be realized more accurate dynamic
State voltage adjusts.Control unit 203 is by the output of a, b and c tri- with respect to PE after common-mode voltage is sampled over the ground, when detecting
Output over the ground common-mode voltage be more than preset value when, the adjustment signal of generation is sent to adjustable DC sources 2021 by control unit 203, adjust
Entire signal is used to indicate current output, and common-mode voltage is excessively high over the ground, it should be adjusted to the voltage value less than preset value.It can
DC sources 2021 is adjusted to adjust N lines to the value of the voltage VNPE of ground wire PE, and then reach tune according to adjustment signal adjustment output voltage
The purpose for exporting the value of common-mode voltage over the ground of whole a, b and c tri- with respect to PE.Exemplary, preset value is 200v (volt), current to examine
The phase voltage VaN of a phases of the three-phase inverting circuit 201 measured to N lines is 110v, and the voltage VNPE of N lines to ground wire PE is 105v,
At this point, control unit 203 detects that common-mode voltage VaPE is 215v, and more than 200v, control unit over the ground for outputs of a with respect to PE
203 generate adjustment signal, and send adjustment signal to adjustable voltage unit 202, notify adjustable voltage unit 202 by VaPE tune
It is whole to 195v, then, the adjustable DC sources 2021 of adjustable voltage unit 202 adjust VNPE to 85v, so that value of VaPE etc.
In 195v.
The entire process for detecting and adjusting can be completed actively, and the value for exporting common-mode voltage over the ground during adjusting begins
It is less than or equal to preset value eventually, i.e., maintains in safe range always.It should be added that control unit 203 is to adjustable
DC sources 2021 can carry out the transmission of signal by 485 communication modes when sending adjustment signal, can also pass through controller local
Net (English：Controller Area Network；Referred to as：CAN) communication mode is transmitted.485 communications are based on RS485
The communication mode that (proposed standard) Data Transport Protocol carries out.Other labels in Fig. 4 can be said with the label in reference chart 3
It is bright.
Optionally, voltage coupler can include at least one of capacitance, resistance and inductance.Fig. 4 is illustrated that voltage
Structure diagram of the coupler for the grid-connected photovoltaic system of capacitance, is coupled to three-phase inverting circuit in the form of capacitance C
201.In addition, voltage coupler 2022 can also be resistance and capacitance series connection, as shown in figure 5, connected with resistance R and capacitance C1
Form is coupled to three-phase inverting circuit 201；Voltage coupler 2022 can also be inductance, as shown in fig. 6, in the form of inductance L
It is coupled to three-phase inverting circuit 201；Can also be the combining form of resistance, capacitance and inductance, the embodiment of the present invention does not do this
It limits.But no matter voltage coupler is coupled to three-phase inverting circuit in what manner, and control unit and adjustable voltage unit are to defeated
Go out the method that common-mode voltage over the ground is detected and adjusts all to be consistent, whole process can be illustrated with reference chart 4, herein
It repeats no more.Other labels in Fig. 5 and Fig. 6 can be illustrated with the label in reference chart 4.
When one end of isolating transformer connection three-phase inverting circuit is without N lines, one kind provided in an embodiment of the present invention
Grid-connected photovoltaic system, as shown in fig. 7, the grid-connected photovoltaic system includes：Three-phase inverting circuit 201, adjustable voltage list
Member 202 and isolating transformer 204, three-phase inverting circuit 201 include control unit 203, and control unit 203 connects adjustable voltage list
Member 202.
Wherein, the input terminal (PV+ ends and PV- ends) of three-phase inverting circuit 201 is connect, three-phase inversion with photovoltaic battery panel 20
The output terminal of circuit 201 is connect with one end of isolating transformer 204, and the other end of isolating transformer 204 is connect with power grid 21.Tool
Body, as shown in fig. 7, three-phase inverting circuit 201 further includes inverter main circuit 2011 and inductance 2012 (i.e. L1, L2 and L3), control
Unit 203 processed is connect with inverter main circuit 2011, and inverter main circuit 2011 is two-stage conversion circuit or level-one conversion circuit.Example
, two-stage conversion circuit can turn DC power supply including DC and DC turns AC power supplies, as shown in Figure 7.Level-one conversion circuit can include
DC turns AC power supplies.It is exemplary, capacitance 20111 can be connected between two-stage conversion circuit.Capacitance is used to inhibit electricity
Flip-flop in corrugating.
Isolating transformer is used to implement the electrical isolation of photovoltaic battery panel and power grid, improves grid-connected photovoltaic system operation
Safety.
As shown in fig. 7, one end of adjustable voltage unit 202 is connect with the output terminal of three-phase inverting circuit 201, another termination
Ground (PE).Specifically, as shown in fig. 7, adjustable voltage unit 202 can include：Adjustable DC sources 2021 and voltage coupler 2022
(i.e. C1, C2 and C3), wherein, the one end (anode+) in adjustable DC sources 2021 passes through voltage coupler 2022 and three-phase inverting circuit
201 output terminal connection, the other end (negative terminal -) ground connection in adjustable DC sources 2021.D in Fig. 7 is in voltage coupler 2022
Point.
Control unit 203 is used for：To the output of three-phase inverting circuit 201, common mode voltage signal samples over the ground, and examines
Surveying output, whether common-mode voltage is more than preset value over the ground, when common-mode voltage is more than preset value over the ground for output, generation adjustment signal,
And send adjustment signal to adjustable voltage unit 202；Adjustable voltage unit 202 is used for：According to adjustment signal to three-phase inversion electricity
Common-mode voltage is adjusted over the ground for the output on road 201.Specifically, as shown in figure 8, control unit 203 detects three-phase inversion respectively
Line voltage Vab, Vca and Vbc of 201 exchange side of circuit, while the midpoint D of voltage coupler 2022 is detected to the voltage of ground wire PE
VDPE with reference to the vector correlation of three-phase symmetrical system, can obtain the output of any time a, b and c tri- with respect to PE common mode over the ground
Voltage VaPE, VbPE and VcPE：
Wherein, the size of the voltage of ∠ -30 ° of expressions of Vab is equal to the size of line voltage Vab, the direction of voltage and line voltage
The angle in the direction of Vab is -30 °；The size of the voltage of ∠ -30 ° of expressions of Vbc is equal to the size of line voltage Vbc, the direction of voltage
Angle with the direction of line voltage Vbc is -30 °；The size of the voltage of ∠ -30 ° of expressions of Vca is equal to the size of line voltage Vca, electricity
The direction of pressure and the angle in the direction of line voltage Vca are -30 °.
By detecting the output of a, b and c tri- with respect to PE, whether common-mode voltage is more than preset value to control unit 203 over the ground, can
To judge whether the exchange side outlet line of three-phase inverting circuit meets dielectric strength requirement under current voltage grade.Work as output
When common-mode voltage is more than preset value over the ground, i.e., exchange side outlet line is unsatisfactory for dielectric strength requirement under current voltage grade
When, the generation adjustment signal of control unit 203, and send adjustment signal to adjustable voltage unit 202.
The output voltage in the adjustable DC sources 2021 of adjustable voltage unit 202 is adjustable, can be realized more accurate dynamic
State voltage adjusts.Control unit 203 is by the output of a, b and c tri- with respect to PE after common-mode voltage is sampled over the ground, when detecting
Output over the ground common-mode voltage be more than preset value when, the adjustment signal of generation is sent to adjustable DC sources 2021 by control unit 203, adjust
Entire signal is used to indicate current output, and common-mode voltage is excessively high over the ground, it should be adjusted to the voltage value less than preset value.It can
DC sources 2021 is adjusted to adjust the voltage of the midpoint D to ground wire PE of voltage coupler 2022 according to adjustment signal adjustment output voltage
The value of VDPE, and then achieve the purpose that adjust the value for exporting common-mode voltage over the ground of a, b and c tri- with respect to PE.
The entire process for detecting and adjusting can be completed actively, and the value for exporting common-mode voltage over the ground during adjusting begins
It is less than or equal to preset value eventually, i.e., maintains in safe range always.It should be added that control unit 203 is to adjustable
DC sources 2021 can carry out the transmission of signal by 485 communication modes when sending adjustment signal, can also pass through CAN communication mode
It is transmitted.Other labels in Fig. 8 can be illustrated with the label in reference chart 7.
Optionally, voltage coupler can include at least one of capacitance, resistance and inductance.Fig. 8 is illustrated that voltage
Structure diagram of the coupler for the grid-connected photovoltaic system of capacitance, is coupled to three in the form of capacitance C1, C2 and C3 parallel connection
Phase inverter circuit 201.In addition, voltage coupler 2022 can also be the series connection of resistance and capacitance, as shown in figure 9, with resistance R1
It is coupled to three-phase inverting circuit with the form of capacitance C1 series connection, resistance R2 and capacitance C2 series connection, resistance R3 and capacitance C3 series connection
201；Voltage coupler 2022 can also be inductance, as shown in Figure 10, be coupled to three-phase inversion in the form of inductance L4, L5 and L6
Circuit 201；Can also be the combining form of resistance, capacitance and inductance, it is not limited in the embodiment of the present invention.But no matter voltage
Coupler be coupled in what manner three-phase inverting circuit, control unit and adjustable voltage unit to export over the ground common-mode voltage into
The method of row detection and adjustment is all consistent, and whole process can be illustrated with reference chart 8, and details are not described herein.Fig. 9 and figure
Other labels in 10 can be illustrated with the label in reference chart 8.
It should be added that during the embodiment of the present invention provides, grid-connected photovoltaic system generates photovoltaic battery panel
The form of alternating current that is converted into of direct current be three-phase electricity, in addition, the form of alternating current can also be single-phase electricity, the present invention is right
This is not construed as limiting.
In conclusion grid-connected photovoltaic system provided in an embodiment of the present invention, by control unit to three-phase inversion electricity
Common mode voltage signal is sampled over the ground for the output on road, and is detected and exported whether common-mode voltage over the ground is more than preset value, works as output
When common-mode voltage is more than preset value over the ground, generation adjustment signal, and send adjustment signal to adjustable voltage unit；Again by adjustable
According to output of the adjustment signal to three-phase inverting circuit, common-mode voltage is adjusted voltage cell over the ground, is completed to three-phase inversion
Common-mode voltage carries out actively monitoring and adjustment over the ground for the output of circuit AC side, so as to which grid-connected photovoltaic system be avoided to run
In the process, the risk of the failure of insulation of exchange side caused by common-mode voltage is beyond the requirement of dielectric strength over the ground due to output,
This improves the safeties of grid-connected photovoltaic system operation.
An embodiment of the present invention provides a kind of application methods of grid-connected photovoltaic system, and as shown in figure 11, the photovoltaic is simultaneously
Net electricity generation system is the grid-connected photovoltaic system described in above device embodiment, which includes three contraries
Become circuit, this method includes：
Step 301, to the output of three-phase inverting circuit, common mode voltage signal samples over the ground, and detects output over the ground altogether
Whether mode voltage is more than preset value, when common-mode voltage is more than preset value over the ground for output, generation adjustment signal.
Step 302, according to output of the adjustment signal to three-phase inverting circuit, common-mode voltage is adjusted over the ground.
In conclusion the application method of grid-connected photovoltaic system provided in an embodiment of the present invention, first to three-phase inversion electricity
Common mode voltage signal is sampled over the ground for the output on road, and is detected and exported whether common-mode voltage over the ground is more than preset value, works as output
When common-mode voltage is more than preset value over the ground, generation adjustment signal；Further according to adjustment signal to the output of three-phase inverting circuit over the ground
Common-mode voltage is adjusted, and completing the output to three-phase inverting circuit exchange side, common-mode voltage carries out actively monitoring and tune over the ground
It is whole, so as to avoid grid-connected photovoltaic system in the process of running, wanted due to exporting common-mode voltage over the ground beyond dielectric strength
The risk of the failure of insulation of exchange side caused by asking, this improves the safeties of grid-connected photovoltaic system operation.
Since one end of isolating transformer connection three-phase inverting circuit may carry N lines, it is also possible to without N lines, with N
Line and different without the specific implementation procedure of the application method of the grid-connected photovoltaic system of N lines.
When one end of isolating transformer connection three-phase inverting circuit carries N lines, with reference to Fig. 4, step 301 can specifically wrap
It includes：Respectively detection three-phase inverting circuit exchange side a phases to N lines phase voltage VaN, b phase to N lines phase voltage VbN and c phase
To the phase voltage VcN of N lines, while N lines are detected to the voltage VNPE of ground wire PE, then can obtain a, b and c tri- relatively by calculating
The output of PE common-mode voltage VaPE, VbPE and VcPE over the ground：
VaPE=VaN+VNPE；
VbPE=VbN+VNPE；
VcPE=VcN+VNPE.
By detecting the output of a, b and c tri- with respect to PE, whether common-mode voltage is more than preset value over the ground, it can be determined that three contraries
Whether the exchange side outlet line for becoming circuit meets dielectric strength requirement under current voltage grade.When output common-mode voltage over the ground
During more than preset value, i.e., when exchange side outlet line is unsatisfactory for dielectric strength requirement under current voltage grade, generation adjustment letter
Number, adjustment signal is used to indicate current output, and common-mode voltage is excessively high over the ground, it should be adjusted to the voltage less than preset value
Value.
Corresponding, step 302 can specifically include：According to adjustment signal adjustment output voltage, that is, N lines are adjusted to ground wire PE
Voltage VNPE value, and then achieve the purpose that adjust the value of the output common-mode voltage over the ground of a, b and c tri- with respect to PE.
When one end of isolating transformer connection three-phase inverting circuit is without N lines, with reference to Fig. 8, step 301 specifically can be with
Including：Line voltage Vab, Vca and Vbc of 201 exchange side of three-phase inverting circuit are detected respectively, while detect voltage coupler 2022
Midpoint D to ground wire PE voltage VDPE, with reference to the vector correlation of three-phase symmetrical system, any time a, b and c tri- can be obtained
Output with respect to PE common-mode voltage VaPE, VbPE and VcPE over the ground：
Wherein, the size of the voltage of ∠ -30 ° of expressions of Vab is equal to the size of line voltage Vab, the direction of voltage and line voltage
The angle in the direction of Vab is -30 °；The size of the voltage of ∠ -30 ° of expressions of Vbc is equal to the size of line voltage Vbc, the direction of voltage
Angle with the direction of line voltage Vbc is -30 °；The size of the voltage of ∠ -30 ° of expressions of Vca is equal to the size of line voltage Vca, electricity
The direction of pressure and the angle in the direction of line voltage Vca are -30 °.
By detecting the output of a, b and c tri- with respect to PE, whether common-mode voltage is more than preset value over the ground, it can be determined that three contraries
Whether the exchange side outlet line for becoming circuit meets dielectric strength requirement under current voltage grade.When output common-mode voltage over the ground
During more than preset value, i.e., when exchange side outlet line is unsatisfactory for dielectric strength requirement under current voltage grade, generation adjustment letter
Number.
Corresponding, step 302 can specifically include：According to adjustment signal adjustment output voltage, that is, adjust voltage coupler
Midpoint D to ground wire PE voltage VDPE value, and then reach outputs of adjustment a, b and the c tri- with respect to PE common-mode voltage over the ground
The purpose of value.The entire process for detecting and adjusting can be completed actively, the value for exporting common-mode voltage over the ground during adjusting
It is consistently less than or equal to preset value, i.e., maintains in safe range always.
It should be noted that the priority of the application method step of grid-connected photovoltaic system provided in an embodiment of the present invention is suitable
Sequence can be adjusted suitably, and step according to circumstances can also accordingly be increased and decreased, any technology people for being familiar with the art
Member in the technical scope disclosed by the present invention, the method that variation can be readily occurred in, should all cover protection scope of the present invention it
Interior, details are not described herein.
In conclusion the application method of grid-connected photovoltaic system provided in an embodiment of the present invention, first to three-phase inversion electricity
Common mode voltage signal is sampled over the ground for the output on road, and is detected and exported whether common-mode voltage over the ground is more than preset value, works as output
When common-mode voltage is more than preset value over the ground, generation adjustment signal；Further according to adjustment signal to the output of three-phase inverting circuit over the ground
Common-mode voltage is adjusted, and completing the output to three-phase inverting circuit exchange side, common-mode voltage carries out actively monitoring and tune over the ground
It is whole, so as to avoid grid-connected photovoltaic system in the process of running, wanted due to exporting common-mode voltage over the ground beyond dielectric strength
The risk of the failure of insulation of exchange side caused by asking, this improves the safeties of grid-connected photovoltaic system operation.
It is apparent to those skilled in the art that for convenience and simplicity of description, the method for foregoing description
Specific implementation procedure, the specific work process of system can refer to the corresponding process in aforementioned device embodiment, no longer superfluous herein
It states.
The foregoing is merely presently preferred embodiments of the present invention, is not intended to limit the invention, it is all the present invention spirit and
Within principle, any modification, equivalent replacement, improvement and so on should all be included in the protection scope of the present invention.
Claims (6)
1. a kind of grid-connected photovoltaic system, which is characterized in that the grid-connected photovoltaic system includes：Three-phase inverting circuit,
Adjustable voltage unit and isolating transformer, the three-phase inverting circuit include control unit, can described in described control unit connection
Adjust voltage cell；
The input terminal of the three-phase inverting circuit is connect with photovoltaic battery panel, the output terminal of the three-phase inverting circuit with it is described every
One end connection from transformer, the other end of the isolating transformer are connect with power grid；
Described control unit is used for：To the output of the three-phase inverting circuit, common mode voltage signal samples over the ground, and detects
Whether common-mode voltage is more than preset value over the ground for the output, raw when common-mode voltage is more than the preset value over the ground for the output
The adjustment signal is sent into adjustment signal, and to the adjustable voltage unit；
The adjustable voltage unit is used for：According to the adjustment signal to the output of three-phase inverting circuit common-mode voltage over the ground
It is adjusted；
Wherein, one end of the adjustable voltage unit is connect with one end of the isolating transformer, other end ground connection, the isolation
One end of transformer connects one end of the three-phase inverting circuit；Alternatively, one end of the adjustable voltage unit and the three-phase
The output terminal connection of inverter circuit, other end ground connection；
The three-phase inverting circuit further includes inverter main circuit and inductance；
Described control unit is connect with the inverter main circuit；
The inverter main circuit is two-stage conversion circuit or level-one conversion circuit.
2. grid-connected photovoltaic system according to claim 1, which is characterized in that the adjustable voltage unit includes：It can
Tuning DC source and voltage coupler；
The one end in the adjustable DC source is connect by the voltage coupler with one end of the isolating transformer, described adjustable
The other end ground connection of DC source, one end of the isolating transformer connect one end of the three-phase inverting circuit；Alternatively, described can
The one end in tuning DC source is connect by the voltage coupler with the output terminal of the three-phase inverting circuit, the adjustable DC source
The other end ground connection.
3. grid-connected photovoltaic system according to claim 2, which is characterized in that the voltage coupler include capacitance,
At least one of resistance and inductance.
4. grid-connected photovoltaic system according to claim 1, which is characterized in that
The two-stage conversion circuit includes DC-DC power supply and direct current turns AC power；
The level-one conversion circuit turns AC power including direct current.
5. grid-connected photovoltaic system according to claim 1, which is characterized in that
Capacitance is connected between the two-stage conversion circuit.
6. a kind of application method of grid-connected photovoltaic system, which is characterized in that the grid-connected photovoltaic system will for right
The grid-connected photovoltaic system described in 1 to 5 any one claim is sought, the grid-connected photovoltaic system includes three-phase inversion
Circuit, the method includes：
To the output of the three-phase inverting circuit, common mode voltage signal samples over the ground, and detects output common mode electricity over the ground
Whether pressure is more than preset value, when common-mode voltage is more than the preset value over the ground for the output, generation adjustment signal；
According to output of the adjustment signal to the three-phase inverting circuit, common-mode voltage is adjusted over the ground.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510290062.5A CN104917200B (en) | 2015-05-29 | 2015-05-29 | Grid-connected photovoltaic system and its application method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510290062.5A CN104917200B (en) | 2015-05-29 | 2015-05-29 | Grid-connected photovoltaic system and its application method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN104917200A CN104917200A (en) | 2015-09-16 |
| CN104917200B true CN104917200B (en) | 2018-06-19 |
Family
ID=54086021
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201510290062.5A Active CN104917200B (en) | 2015-05-29 | 2015-05-29 | Grid-connected photovoltaic system and its application method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104917200B (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102273039A (en) * | 2008-11-07 | 2011-12-07 | 丹佛斯太阳能变极器有限公司 | Photovoltaic power plant having an offset voltage source controlling the DC potential at the inverter output |
| CN103337874A (en) * | 2013-06-09 | 2013-10-02 | 阳光电源股份有限公司 | Photovoltaic power generation system, and voltage compensation device and converter applicable to same |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101527505B (en) * | 2009-03-31 | 2012-05-23 | 西安交通大学 | Disturbance voltage attenuation device |
| CN101667789B (en) * | 2009-04-14 | 2012-05-30 | 初萍 | Inverter circuit used for solar energy photovoltaic grid connection and device thereof |
| CN104201919B (en) * | 2014-09-05 | 2019-08-16 | 爱士惟新能源技术(上海)有限公司 | A kind of electric leakage method of flow control of photovoltaic DC-to-AC converter |
| CN104467387A (en) * | 2014-12-01 | 2015-03-25 | 沈阳工业大学 | Active filter restraining common-mode voltage of frequency converter |
-
2015
- 2015-05-29 CN CN201510290062.5A patent/CN104917200B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102273039A (en) * | 2008-11-07 | 2011-12-07 | 丹佛斯太阳能变极器有限公司 | Photovoltaic power plant having an offset voltage source controlling the DC potential at the inverter output |
| CN103337874A (en) * | 2013-06-09 | 2013-10-02 | 阳光电源股份有限公司 | Photovoltaic power generation system, and voltage compensation device and converter applicable to same |
Also Published As
| Publication number | Publication date |
|---|---|
| CN104917200A (en) | 2015-09-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP3460936B1 (en) | Pilot protection method for transmission line of new energy station based on current waveform similarity | |
| CN103048544B (en) | Insulation resistance monitoring method of photovoltaic power generation system | |
| CN104868764B (en) | Inverter and its power conversion method | |
| CN202583327U (en) | Insulation impedance detection circuit of photovoltaic grid-connected inverter with double-circuit MPPT (Maximum Power Point Tracking) | |
| CN105652097B (en) | A kind of grid-connected photovoltaic system and its grid side insulation resistance detection device | |
| CN104124701B (en) | A kind of photovoltaic combining inverter DC component inhibition method | |
| CN103746622A (en) | Single-tube IGBT (Insulated Gate Bipolar Translator)-based three-stage brushless generator power control device and power control method | |
| EP2947743A2 (en) | Converter and operating method thereof | |
| CN107086600A (en) | A kind of solar energy power generating three phase full bridge grid-connected inverting system | |
| WO2015192666A1 (en) | Inverter power system | |
| CN107505533A (en) | The live wire earth-fault detecting method and sampled signal processing method of combining inverter | |
| CN105406516B (en) | Anti- PID devices, anti-PID grid-connected photovoltaic systems and anti-PID approach | |
| CN108767901A (en) | A kind of three-phase grid-connected inverter anti-backflow device and control method | |
| Kumar et al. | Wavelet singular entropy approach for fault detection and classification of transmission line compensated with UPFC | |
| CN108288920A (en) | The method for inhibiting photovoltaic combining inverter DC bus-bar voltage secondary ripple wave to influence MPPT | |
| CN104917200B (en) | Grid-connected photovoltaic system and its application method | |
| Liu et al. | The control strategy for Hybrid HVDC using voltage margin control and voltage dependent current order limiter control | |
| CN110311415A (en) | A kind of transient stability margin appraisal procedure suitable for renewable energy power generation base during low voltage crossing | |
| WO2023077741A1 (en) | Photovoltaic system and control method | |
| CN104979822A (en) | Operating system for power quality management of intelligent micro-grid | |
| Tang et al. | A novel directional relay applicable to power system with wind farms | |
| CN112379171A (en) | Direct-current ground insulation impedance detection circuit and method for bridge arm topology converter | |
| CN112379172A (en) | High-precision direct current ground insulation impedance detection circuit and method | |
| CN103227451B (en) | A kind of line voltage owes overvoltage detection protecting method and device | |
| CN109936298B (en) | Rectifier circuit and power supply device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20211109 Address after: 518043 No. 01, 39th floor, building a, antuoshan headquarters building, No. 33, antuoshan Sixth Road, Xiang'an community, Xiangmihu street, Futian District, Shenzhen, Guangdong Province Patentee after: Huawei Digital Energy Technology Co.,Ltd. Address before: 518129 Bantian HUAWEI headquarters office building, Longgang District, Guangdong, Shenzhen Patentee before: HUAWEI TECHNOLOGIES Co.,Ltd. |