CN107147319A - Non-isolated grid-connected inverter, grid-connected photovoltaic system and control method - Google Patents
Non-isolated grid-connected inverter, grid-connected photovoltaic system and control method Download PDFInfo
- Publication number
- CN107147319A CN107147319A CN201710587318.8A CN201710587318A CN107147319A CN 107147319 A CN107147319 A CN 107147319A CN 201710587318 A CN201710587318 A CN 201710587318A CN 107147319 A CN107147319 A CN 107147319A
- Authority
- CN
- China
- Prior art keywords
- unidirectional power
- power switch
- inductance
- grid
- control
- 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.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 22
- 230000005611 electricity Effects 0.000 claims description 6
- 238000001914 filtration Methods 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 5
- 239000003990 capacitor Substances 0.000 description 3
- 230000001965 increasing effect Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 230000001939 inductive effect Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000010276 construction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- SJWPTBFNZAZFSH-UHFFFAOYSA-N pmpp Chemical compound C1CCSC2=NC=NC3=C2N=CN3CCCN2C(=O)N(C)C(=O)C1=C2 SJWPTBFNZAZFSH-UHFFFAOYSA-N 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000013083 solar photovoltaic technology Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/01—Arrangements for reducing harmonics or ripples
-
- H02J3/383—
-
- H02J3/385—
-
- 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
-
- 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
-
- 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
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
Abstract
The invention discloses a kind of non-isolated grid-connected inverter, grid-connected photovoltaic system and control method, inverter includes the electric capacity C in parallel with photovoltaic battery panelPV, electric capacity CPVTwo ends VT is switched by unidirectional power respectively1, unidirectional power switch VT2With inductance LcTwo ends connection, unidirectional power switch VT3, unidirectional power switch VT4Inductance L is connected in parallel on after series connectioncTwo ends.Grid-connected photovoltaic system includes the non-isolated grid-connected inverter.Also disclose a kind of control method to grid-connected photovoltaic system.The present invention reduces the use of component, reduces the volume and use cost of inverter by using current source inverter, it is to avoid the drawbacks of Ground leakage current.
Description
Technical field
The present invention relates to solar photovoltaic technology field, more particularly to a kind of single-phase single-grade non-isolated current source type
Inverter, grid-connected photovoltaic system and control method.
Background technology
As environment, energy problem are of increased attention, parallel network power generation is used as renewable energy utilization
Technology has obtained extensive attention.But be due to grid-connected photovoltaic system up-front investment it is larger, cost of electricity-generating is higher etc. because
Element, seriously hinders popularizing for grid-connected photovoltaic system.
Grid-connected photovoltaic system generally comprises photovoltaic battery panel and combining inverter, and grid-connected system is by photovoltaic cell
The solar radiation energy that plate is received is converted into HVDC by high-frequency direct-current, then defeated to power network after inverter inversion
Go out with line voltage with frequency, with the simple sinusoidal alternating current of phase.Wherein, combining inverter includes voltage source inverter and current mode is inverse
Become the major class of device two, current source inverter can improve DC input voitage, with short-circuit protection ability.And because current mode is inverse
Becoming device does not have dc-link capacitance, therefore improves the service life of current source inverter.
But, the use of inverter of the cost and volumetric constraint of inverter, current solution is to use non-isolated
The inverter of type, due to eliminating bulky isolating transformer in photovoltaic parallel in system so that system has simple in construction, again
Amount is light, low cost and other advantages.But it is due to photovoltaic battery panel and public electric wire net in the photovoltaic parallel in system without isolating transformer
Do not isolate, this will cause photovoltaic battery panel and line voltage to connect so that there is this between photovoltaic battery panel and the earth right
Ground electric capacity, therefore the leakage current of photovoltaic battery panel over the ground can be produced, the operating efficiency of inverter is reduced, grid-connected current is added
Distortion, reduce grid-connected security.
The content of the invention
It is an object of the invention to provide a kind of non-isolated grid-connected inverter, grid-connected photovoltaic system and controlling party
Method, the problem of to solve photovoltaic battery panel Ground leakage current.
To realize object above, first aspect present invention provides a kind of non-isolated grid-connected inverter, including：With photovoltaic
Cell panel electric capacity C in parallelPV, electric capacity CPVTwo ends VT is switched by unidirectional power respectively1, unidirectional power switch VT2With inductance
LcTwo ends connection, unidirectional power switch VT3, unidirectional power switch VT4Inductance L is connected in parallel on after series connectioncTwo ends.
Wherein, electric capacity CPVFor decoupling capacitor.
Wherein, electric capacity CPVPositive pole and unidirectional power switch VT1Colelctor electrode connection, unidirectional power switch VT1Transmitting
Pole and the inductance LcOne end connection, base earth；
Electric capacity CPVNegative pole and unidirectional power switch VT2Emitter stage connection, unidirectional power switch VT2Colelctor electrode and institute
State inductance LcThe other end connection, base earth；
Unidirectional power switchs VT3Emitter stage and unidirectional power switch VT4Colelctor electrode connection, unidirectional power switch VT4's
Emitter stage and the inductance LcOne end connection, base earth, unidirectional power switch VT3Colelctor electrode and the inductance LcIt is another
One end connection, base earth.
Second aspect there is provided a kind of grid-connected photovoltaic system, including：
Photovoltaic battery panel, wave filter and above-mentioned non-isolated grid-connected inverter, photovoltaic battery panel and described electricity
Hold CPVParallel connection, a port of wave filter is connected with non-isolated grid-connected inverter, the other end and power network are connected.
Wherein, wave filter includes electric capacity CfWith inductance Lf, electric capacity CfOne end and inductance LfOne end connection after with unidirectional work(
Rate switchs VT3Emitter stage switchs VT with unidirectional power4Colelctor electrode connecting line is connected, electric capacity CfThe other end and described photovoltaic electric
The negative pole connection of pond plate, electric capacity CfThe other end, inductance LfThe other end be connected respectively with the two ends of power network.
The third aspect there is provided a kind of control method to above-mentioned grid-connected photovoltaic system, including：
Control the unidirectional power switch VT1VT is switched with unidirectional power2Conducting, unidirectional power switch VT3And unidirectional power
Switch VT4Disconnect, the photovoltaic battery panel is to the inductance LcCharging, system works in inductance LcCharge mode；
Control the unidirectional power switch VT1VT is switched with unidirectional power3Conducting, unidirectional power switch VT2And unidirectional power
Switch VT4Disconnect, the photovoltaic battery panel and the inductance LcElectric discharge, the positive electricity of non-isolated grid-connected inverter output
Stream and with inductance LcCurrent value is identical, and system works in inverter output forward current pattern；
Control the unidirectional power switch VT2VT is switched with unidirectional power4Conducting, unidirectional power switch VT1And unidirectional power
Switch VT3Close, non-isolated grid-connected inverter output reverse current and with inductance LcCurrent value is identical, system work
Reverse current flow mode is exported in inverter；
Control the unidirectional power switch VT3VT is switched with unidirectional power4Conducting, unidirectional power switch VT1And unidirectional power
Switch VT2Disconnect, inductance LcCurrent value keeps constant, and the non-isolated grid-connected inverter output current value is zero, system work
Make in inductance LcFreewheeling mode.
Wherein, current hysteresis-band control is carried out to above-mentioned non-isolated grid-connected inverter, including to the positive half cycle of grid-connected current
The control of phase and the control to grid-connected current negative half-cycle.
Wherein, grid-connected current positive half period is controlled, and is specifically included：
Gather t1The electric current i at momentg, in ig＜ iminWhen, control the unidirectional power switch VT1VT is switched with unidirectional power3
Conducting, system works in inverter output forward current pattern, to control igIncrease to track grid-connected current set-point iref；
In imin＜ ig＜ imaxWhen, if judging the inductance LcCurrent value iLC＜ iLC-ref, control the unidirectional power switch
VT1, unidirectional power switch VT2Conducting, system works in inductance LcCharge mode；
In imin＜ ig＜ imaxWhen, if judging the inductance LcCurrent value iLC＞ iLC-ref, control the unidirectional power switch
VT3VT is switched with unidirectional power4Conducting, system works in inductance LcFreewheeling mode；
In ig＞ imaxWhen, if judging iLC＞ iLC-ref, control the unidirectional power switch VT2VT is switched with unidirectional power4Lead
Logical, system works in inverter output reverse current flow mode to control igReduce；
In ig＞ imaxWhen, if judging iLC＜ iLC-ref, the unidirectional power switch VT1, unidirectional power switch VT2Conducting, be
System works in inductance LcCharge mode is to control igReduce, wherein iLC-re fFor inductive current iLCReference value.
Wherein, grid-connected current negative half-cycle is controlled, and is specifically included：
Gather t1The electric current i at momentg, in ig＞ imaxWhen, control the unidirectional power switch VT2VT is switched with unidirectional power4
Conducting, system works in inverter output reverse current flow mode to control igReduce；
In imin＜ ig＜ imaxWhen, if judging the inductance LcCurrent value iLC＜ iLC-ref, control the unidirectional power switch
VT1, unidirectional power switch VT2Conducting, system works in inductance LcCharge mode；
In imin＜ ig＜ imaxWhen, if judging the inductance LcCurrent value iLC＞ iLC-ref, control the unidirectional power switch
VT3VT is switched with unidirectional power4Conducting, system works in inductance LcFreewheeling mode；
In ig＜ iminWhen, if judging iLC＞ iLC-ref, control the unidirectional power switch VT1VT is switched with unidirectional power3Lead
Logical, system works in inverter output forward current pattern, to control igIncrease to track grid-connected current set-point iref；
In ig＞ imaxWhen, if judging iLC＜ iLC-ref, the unidirectional power switch VT1, unidirectional power switch VT2Conducting, be
System works in inductance LcCharge mode is to control igReduce.
Wherein, i is controlledgIncrease to track grid-connected current set-point iref, specifically include：
The output voltage of the photovoltaic battery panel, the voltage of the collection power network, which are gathered, using voltage sensor exchanges letter
Number, and utilize the output current of the current sensor collection photovoltaic battery panel；
The peak power of the photovoltaic battery panel is calculated according to maximal power tracing algorithm；
According to the peak power of the photovoltaic battery panel, the given amplitude of grid-connected current is calculated；
After the low-pass filtered device filtering of the voltage AC signal of the power network, phase angle letter is obtained into single-phase phase-locked loop
Number；
According to phase angle signal and the given amplitude of grid-connected current, grid-connected current set-point i is calculatedrefTo realize control igIncrease
Big tracking grid-connected current set-point iref。
Compared with prior art, there is following technique effect in the present invention：Non-isolated grid-connected inversion proposed by the present invention
Four unidirectional power switch control electric current one-way flows are employed in device, without increasing anti-paralleled diode in inverter, with
Traditional non-isolated current source type photovoltiac parallel inverter is compared, and the component used is less, reduce the use cost of inverter
And reduce the volume of inverter.Meanwhile, in grid-connected photovoltaic system, the electric capacity of photovoltaic battery panel over the ground is bypassed,
The method of operation of China 220V/380V widely used neutral-point solid ground of low-voltage distribution system, unidirectional power network grounding resistance
It is similar to zero, so the both end voltage of photovoltaic battery panel direct-to-ground capacitance is constant, therefore flows through photovoltaic battery panel direct-to-ground capacitance
Electric current be similar to zero, eliminate the Leaked Current of Line to Ground phenomenon of photovoltaic combining inverter.
Brief description of the drawings
Below in conjunction with the accompanying drawings, the embodiment to the present invention is described in detail：
Fig. 1 is a kind of electrical block diagram of non-isolated grid-connected inverter in the present invention；
Fig. 2 is a kind of structural representation of grid-connected photovoltaic system in the present invention；
Fig. 3 is non-isolated grid-connected inverter Ground leakage current path schematic diagram in the present invention；
Fig. 4 is that grid-connected photovoltaic system is operated in the schematic equivalent circuit under induction charging pattern in the present invention；
The equivalent circuit that grid-connected photovoltaic system is operated under inverter output forward current pattern in Fig. 5 present invention shows
It is intended to；
Fig. 6 is that grid-connected photovoltaic system is operated in the equivalent circuit under inverter output reverse current flow mode in the present invention
Schematic diagram；
Fig. 7 is that grid-connected photovoltaic system is operated in the circuit diagram under inductance freewheeling mode in the present invention；
Fig. 8 is the equivalent schematic being controlled using Hysteresis Current to non-isolated grid-connected inverter in the present invention；
Fig. 9 is the schematic flow sheet being controlled to grid-connected current positive half period in the present invention；
Figure 10 is the schematic flow sheet being controlled to grid-connected current negative half-cycle in the present invention；
Figure 11 is real-time calculating grid-connected current set-point i in the present inventionrefSchematic flow sheet.
Embodiment
In order to illustrate further the feature of the present invention, please refer to the following detailed descriptions related to the present invention and accompanying drawing.Institute
Accompanying drawing is only for reference and purposes of discussion, not for being any limitation as to protection scope of the present invention.
Embodiment one
As shown in figure 1, present embodiment discloses a kind of non-isolated grid-connected inverter, including：Electric capacity CPV, inductance LcWith
And four unidirectional power switches, electric capacity CPVTwo ends VT is switched by unidirectional power respectively1, unidirectional power switch VT2With inductance Lc
Two ends connection, unidirectional power switch VT3, unidirectional power switch VT4Inductance L is connected in parallel on after series connectioncTwo ends.
Further, above-mentioned electric capacity CPVFor decoupling capacitor.Decoupling capacitor is arranged on the two ends of power supply, can provide and compare
Stable power supply so that the dc source of input will not be short-circuit because of the failure of switching device.Simultaneously as in the present embodiment
Inverter be current source inverter, input voltage can be improved so that single photovoltaic battery panel can be directly connected to single-phase
Power network.
Further, electric capacity CPVPositive pole and unidirectional power switch VT1Colelctor electrode connection, unidirectional power switch VT1's
Emitter stage and the inductance LcOne end connection, base earth；
Electric capacity CPVNegative pole and unidirectional power switch VT2Emitter stage connection, unidirectional power switch VT2Colelctor electrode and institute
State inductance LcThe other end connection, base earth；
Unidirectional power switchs VT3Emitter stage and unidirectional power switch VT4Colelctor electrode connection, unidirectional power switch VT4's
Emitter stage and the inductance LcOne end connection, base earth, unidirectional power switch VT3Colelctor electrode and the inductance LcIt is another
One end connection, base earth.
Combining inverter uses current source inverter, electric capacity C in the present embodimentPVElectric current iPVFrom photovoltaic cell
The positive pole of plate is unidirectionally flowed out, and only needs unidirectional power switch to meet requirement, without increasing anti-paralleled diode so that inverse
The quantity of the component become in device is reduced, and is reduced the cost of inverter and is reduced the volume of inverter.
Embodiment two
As shown in Fig. 2 present embodiment discloses a kind of grid-connected photovoltaic system, including：Photovoltaic battery panel 10, wave filter
20 and above-mentioned non-isolated grid-connected inverter 30, photovoltaic battery panel 10 and electric capacity CPVParallel connection, an end of wave filter 20
Mouth is connected with non-isolated grid-connected inverter 30, the other end and power network 40 are connected.
Further, wave filter 20 includes electric capacity CfWith inductance Lf, electric capacity CfOne end and inductance LfOne end connection after with
Unidirectional power switchs VT3Emitter stage switchs VT with unidirectional power4Colelctor electrode connecting line is connected, electric capacity CfThe other end with it is described
The negative pole connection of photovoltaic battery panel, electric capacity CfThe other end, inductance LfThe other end be connected respectively with the two ends of power network.
It should be noted that the path schematic diagram of non-isolated grid-connected inverter Ground leakage current as shown in figure 3, its
In, CGroundRepresent the electric capacity of photovoltaic battery panel 10 over the ground, RGroundThe grounding resistance of unidirectional power network 40 is represented,C is flowed through in expressionGroundElectric current
That is leakage current：Due to CGroundIt is bypassed, and China is the low with electrical voltage system of 220V/380V, it is widely used
The method of operation of neutral-point solid ground, so RGround≈ 0, CGroundThe voltage constant at two ends.ThereforeTherefore it is public in the present embodiment
The non-isolated grid-connected inverter 30 opened eliminates Leaked Current of Line to Ground flow phenomenon, improves the efficiency of inverter.
Embodiment three
As shown in Fig. 4 to 7, present embodiment discloses a kind of control method to above-mentioned grid-connected photovoltaic system, in Fig. 4
Into 7, dotted line indication circuit is off-state, and solid line indication circuit is channel status.The control process includes four kinds of patterns：
Inductance LcCharge mode：As shown in figure 4, control unidirectional power switch VT1VT is switched with unidirectional power2Turn on, unidirectionally
Power switch VT3VT is switched with unidirectional power4Disconnect, photovoltaic battery panel 10 is to inductance LcCharging, single-phase power network 40 and inductance Lf、
Electric capacity CfConstitute closed-loop path, the output current i of non-isolated grid-connected inverter 30invIt is zero.
Inverter exports forward current pattern：As shown in figure 5, control unidirectional power switch VT1VT is switched with unidirectional power3
Conducting, unidirectional power switch VT2VT is switched with unidirectional power4Disconnect, photovoltaic battery panel 10 and inductance LcElectric discharge releases energy, non-
The output forward current of isolated grid-connected inverter 30 iinvAnd with inductance LcThe identical i.e. i of current valueLC=iinv。
Inverter exports reverse current flow mode：As shown in fig. 6, control unidirectional power switch VT2VT is switched with unidirectional power4
Conducting, unidirectional power switch VT1VT is switched with unidirectional power3Close, the output reverse current of non-isolated grid-connected inverter 30
iinvAnd with inductance LcCurrent value iLCIt is identical.
Inductance LcFreewheeling mode：As shown in fig. 7, control unidirectional power switch VT3VT is switched with unidirectional power4Turn on, unidirectionally
Power switch VT1VT is switched with unidirectional power2Disconnect, inductance LcCurrent value iLCKeep constant, non-isolated grid-connected inverter 30
Output current value iinvIt is zero.
Further, the present embodiment uses current hysteresis-band control to non-isolated grid-connected inverter 3, including to grid-connected electricity
Flow the control and the control to grid-connected current negative half-cycle of positive half period.
In actual applications, for easy to operate, actual grid-connected current igRepresent, grid-connected current set-point irefTable
Show, inductance LcThe given reference value i of electric currentLC-refRepresent, because the inverter in the present embodiment is current source inverter,
So reference current value iLC-refFor DC quantity.
iref=IrefSin (ω t+ θ),
Wherein, IrefThe amplitude given for grid-connected current, ω is electrical network angular frequency, and θ is initial phase angle.
Due to the output current i of non-isolated grid-connected inverter 30invFor PWM electric currents, its value is equal to inductance LcElectric current iLC,
In order to which energy is exported to single-phase power network 40, i by photovoltaic battery panel 10invIt should be greater than Iref, i.e. inductance LcThe given reference value of electric current
iLC-refIt should be greater than Iref, i is set in the present embodimentLC-ref=3Iref.In order to which guarantor unit's power factor is grid-connected, grid-connected current should
With line voltage same-phase, therefore the voltage expression of power network 40 is：ug=UmSin (ω t+ θ), wherein ugIt is instantaneous for line voltage
Value, UmFor grid voltage amplitude.
As shown in figure 8, during Hysteresis control, controlling what four unidirectional powers were switched according to current tracking deviation
Open/close state, wherein stagnant ring ring width is represented with H, actual grid-connected current igControl result should meet imin＜ ig＜ imax, wherein：
imax=iref+ H=Irefsin(ωt+θ)+H,
imin=iref- H=Irefsin(ωt+θ)-H。
Further, as shown in figure 9, the control process to grid-connected current positive half period is specifically included：
Gather t1The electric current i at momentg, in ig＜ iminWhen, control the unidirectional power switch VT1VT is switched with unidirectional power3
Conducting, system works in inverter output forward current pattern, to control igIncrease to track grid-connected current set-point iref；
In imin＜ ig＜ imaxWhen, if judging the inductance LcCurrent value iLC＜ iLC-ref, control the unidirectional power switch
VT1, unidirectional power switch VT2Conducting, system works in inductance LcCharge mode；
In imin＜ ig＜ imaxWhen, if judging the inductance LcCurrent value iLC＞ iLC-ref, control the unidirectional power switch
VT3VT is switched with unidirectional power4Conducting, system works in inductance LcFreewheeling mode；
In ig＞ imaxWhen, if judging iLC＞ iLC-ref, control the unidirectional power switch VT2VT is switched with unidirectional power4Lead
Logical, system works in inverter output reverse current flow mode to control igReduce；
In ig＞ imaxWhen, if judging iLC＜ iLC-ref, the unidirectional power switch VT1, unidirectional power switch VT2Conducting, be
System works in inductance LcCharge mode is to control igReduce, wherein iLC-re fFor inductive current iLCReference value.
Further, as shown in Figure 10, the control process to grid-connected current negative half-cycle includes：
Gather t1The electric current i at momentg, in ig＞ imaxWhen, control the unidirectional power switch VT2VT is switched with unidirectional power4
Conducting, system works in inverter output reverse current flow mode to control igReduce；
In imin＜ ig＜ imaxWhen, if judging the inductance LcCurrent value iLC＜ iLC-ref, control the unidirectional power switch
VT1, unidirectional power switch VT2Conducting, system works in inductance LcCharge mode；
In imin＜ ig＜ imaxWhen, if judging the inductance LcCurrent value iLC＞ iLC-ref, control the unidirectional power switch
VT3VT is switched with unidirectional power4Conducting, system works in inductance LcFreewheeling mode；
In ig＜ iminWhen, if judging iLC＞ iLC-ref, control the unidirectional power switch VT1VT is switched with unidirectional power3Lead
Logical, system works in inverter output forward current pattern, to control igIncrease to track grid-connected current set-point iref；
In ig＞ imaxWhen, if judging iLC＜ iLC-ref, the unidirectional power switch VT1, unidirectional power switch VT2Conducting, be
System works in inductance LcCharge mode is to control igReduce.It is as follows：
It should be noted that the DC voltage of inverter have to be larger than single phase ac in voltage-type photovoltaic combining inverter
The peak value of line voltage, will could typically be realized and be incorporated into the power networks in more than 350V, and the output voltage of single photovoltaic module is not up to
Arrive, in order to meet voltage matches, general photovoltaic combining inverter prime has a DC-DC converter and above-described embodiment is disclosed
Non-isolated grid-connected inverter use current source inverter, itself has the ability of boosting, therefore does not need volume
Outer DC-DC converter.
According to the peak power P of photovoltaic battery panel 10mppGrid-connected current set-point i is obtained to calculateref, by the electric current
The tracking of photovoltaic battery panel peak power is realized in the tracking of set-point.Therefore, inversion is leaned in the tracking of photovoltaic battery panel peak power
Device can be achieved in itself.
Pgrid=η Pmpp,
Wherein, PgridRepresent that non-isolated grid-connected inverter 30 is output to the power of single-phase power network 40, η is non-isolated light
Lie prostrate the efficiency of combining inverter 30.
As shown in figure 11, i is controlledgIncrease to track grid-connected current set-point iref, specifically include：
The output voltage U of photovoltaic battery panel 10 is gathered using voltage sensorPV, collection power network 40 instantaneous voltage ug,
And the output current I of photovoltaic battery panel 10 is gathered using current sensorPV；
The peak power of photovoltaic battery panel 10 is calculated according to maximal power tracing algorithm；
It should be noted that maximal power tracing algorithm here includes but is not limited to perturbation observation method, conductance modulation method
Etc. method.
According to the peak power of photovoltaic battery panel 10, the given amplitude I of grid-connected current is calculatedref；
After the low-pass filtered device filtering of the voltage AC signal of power network 40, phase angle signal is obtained into single-phase phase-locked loop
sin(ωt+θ)；
According to phase angle signal and the given amplitude of grid-connected current, grid-connected current set-point i is calculatedrefTo realize control igIncrease
Big tracking grid-connected current set-point iref。
The foregoing is only presently preferred embodiments of the present invention, be not intended to limit the invention, it is all the present invention spirit and
Within principle, any modification, equivalent substitution and improvements made etc. should be included in the scope of the protection.
Claims (10)
1. a kind of non-isolated grid-connected inverter, it is characterised in that including：Electric capacity CPV, inductance LcAnd four unidirectional powers
Switch, electric capacity CPVTwo ends VT is switched by unidirectional power respectively1, unidirectional power switch VT2With inductance LcTwo ends connection, it is single
To power switch VT3, unidirectional power switch VT4Inductance L is connected in parallel on after series connectioncTwo ends.
2. non-isolated grid-connected inverter as claimed in claim 1, it is characterised in that described electric capacity CPVFor decoupling electricity
Hold.
3. non-isolated grid-connected inverter as claimed in claim 1, it is characterised in that described electric capacity CPVPositive pole and list
To power switch VT1Colelctor electrode connection, unidirectional power switch VT1Emitter stage and the inductance LcOne end connection, base stage connects
Ground；
Electric capacity CPVNegative pole and unidirectional power switch VT2Emitter stage connection, unidirectional power switch VT2Colelctor electrode and the electricity
Feel LcThe other end connection, base earth；
Unidirectional power switchs VT3Emitter stage and unidirectional power switch VT4Colelctor electrode connection, unidirectional power switch VT4Transmitting
Pole and the inductance LcOne end connection, base earth, unidirectional power switch VT3Colelctor electrode and the inductance LcThe other end
Connection, base earth.
4. a kind of grid-connected photovoltaic system, it is characterised in that including：Photovoltaic battery panel, wave filter and such as claim 1-3
Non-isolated grid-connected inverter described in any one, photovoltaic battery panel and described electric capacity CPVParallel connection, an end of wave filter
Mouth is connected with non-isolated grid-connected inverter, the other end and power network are connected.
5. grid-connected photovoltaic system as claimed in claim 4, it is characterised in that described wave filter includes electric capacity CfAnd electricity
Feel Lf, electric capacity CfOne end and inductance LfOne end connection after with unidirectional power switch VT3Emitter stage switchs VT with unidirectional power4Collection
Electrode connecting line is connected, electric capacity CfThe other end be connected with the negative pole of described photovoltaic battery panel, electric capacity CfThe other end, inductance
LfThe other end be connected respectively with the two ends of power network.
6. a kind of control method of grid-connected photovoltaic system as described in claim any one of 4-5, it is characterised in that bag
Include：
Control the unidirectional power switch VT1VT is switched with unidirectional power2Conducting, unidirectional power switch VT3With unidirectional power switch
VT4Disconnect, the photovoltaic battery panel is to the inductance LcCharging, system works in inductance LcCharge mode；
Control the unidirectional power switch VT1VT is switched with unidirectional power3Conducting, unidirectional power switch VT2With unidirectional power switch
VT4Disconnect, the photovoltaic battery panel and the inductance LcElectric discharge, non-isolated grid-connected inverter output forward current and
With inductance LcCurrent value is identical, and system works in inverter output forward current pattern；
Control the unidirectional power switch VT2VT is switched with unidirectional power4Conducting, unidirectional power switch VT1With unidirectional power switch
VT3Close, non-isolated grid-connected inverter output reverse current and with inductance LcCurrent value is identical, and system works in inverse
Become device output reverse current flow mode；
Control the unidirectional power switch VT3VT is switched with unidirectional power4Conducting, unidirectional power switch VT1With unidirectional power switch
VT2Disconnect, inductance LcCurrent value keeps constant, and the non-isolated grid-connected inverter output current value is zero, and system is worked in
Inductance LcFreewheeling mode.
7. control method as claimed in claim 6, it is characterised in that also include：
Carry out current hysteresis-band control to the non-isolated grid-connected inverter, including control to grid-connected current positive half period and
Control to grid-connected current negative half-cycle.
8. control method as claimed in claim 7, it is characterised in that described grid-connected current positive half period control, specific bag
Include：
Gather t1The electric current i at momentg, in ig＜ iminWhen, control the unidirectional power switch VT1VT is switched with unidirectional power3Lead
Logical, system works in inverter output forward current pattern, to control igIncrease to track grid-connected current set-point iref；
In imin＜ ig＜ imaxWhen, if judging the inductance LcCurrent value iLC＜ iLC-ref, control the unidirectional power switch VT1、
Unidirectional power switchs VT2Conducting, system works in inductance LcCharge mode；
In imin＜ ig＜ imaxWhen, if judging the inductance LcCurrent value iLC＞ iLC-ref, control the unidirectional power switch VT3With
Unidirectional power switchs VT4Conducting, system works in inductance LcFreewheeling mode；
In ig＞ imaxWhen, if judging iLC＞ iLC-ref, control the unidirectional power switch VT2VT is switched with unidirectional power4Conducting,
System works in inverter output reverse current flow mode to control igReduce；
In ig＞ imaxWhen, if judging iLC＜ iLC-ref, the unidirectional power switch VT1, unidirectional power switch VT2Conducting, system work
Make in inductance LcCharge mode is to control igReduce, wherein iLC-refFor inductance LcElectric current iLCReference value.
9. control method as claimed in claim 8, it is characterised in that described grid-connected current negative half-cycle control, specific bag
Include：
Gather t1The electric current i at momentg, in ig＞ imaxWhen, control the unidirectional power switch VT2VT is switched with unidirectional power4Lead
Logical, system works in inverter output reverse current flow mode to control igReduce；
In imin＜ ig＜ imaxWhen, if judging the inductance LcCurrent value iLC＜ iLC-ref, control the unidirectional power switch VT1、
Unidirectional power switchs VT2Conducting, system works in inductance LcCharge mode；
In imin＜ ig＜ imaxWhen, if judging the inductance LcCurrent value iLC＞ iLC-ref, control the unidirectional power switch VT3With
Unidirectional power switchs VT4Conducting, system works in inductance LcFreewheeling mode；
In ig＜ iminWhen, if judging iLC＞ iLC-ref, control the unidirectional power switch VT1VT is switched with unidirectional power3Conducting,
System works in inverter output forward current pattern, to control igIncrease to track grid-connected current set-point iref；
In ig＞ imaxWhen, if judging iLC＜ iLC-ref, the unidirectional power switch VT1, unidirectional power switch VT2Conducting, system work
Make in inductance LcCharge mode is to control igReduce.
10. control method as claimed in claim 8 or 9, it is characterised in that described control igIncrease to track grid-connected current
Set-point iref, specifically include：
The output voltage of the photovoltaic battery panel is gathered using voltage sensor, gather the voltage AC signal of the power network, with
And the output current of the photovoltaic battery panel is gathered using current sensor；
The peak power of the photovoltaic battery panel is calculated according to maximal power tracing algorithm；
According to the peak power of the photovoltaic battery panel, the given amplitude of grid-connected current is calculated；
After the low-pass filtered device filtering of the voltage AC signal of the power network, phase angle signal is obtained into single-phase phase-locked loop；
According to phase angle signal and the given amplitude of grid-connected current, grid-connected current set-point i is calculatedrefTo realize control igIncrease tracking
Grid-connected current set-point iref。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710587318.8A CN107147319B (en) | 2017-07-18 | 2017-07-18 | Non-isolated photovoltaic grid-connected inverter, photovoltaic grid-connected power generation system and control method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710587318.8A CN107147319B (en) | 2017-07-18 | 2017-07-18 | Non-isolated photovoltaic grid-connected inverter, photovoltaic grid-connected power generation system and control method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107147319A true CN107147319A (en) | 2017-09-08 |
| CN107147319B CN107147319B (en) | 2020-07-28 |
Family
ID=59776181
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710587318.8A Active CN107147319B (en) | 2017-07-18 | 2017-07-18 | Non-isolated photovoltaic grid-connected inverter, photovoltaic grid-connected power generation system and control method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107147319B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107947617A (en) * | 2017-10-23 | 2018-04-20 | 胡炎申 | A kind of hybrid switch single-phase inverter |
| CN109194175A (en) * | 2018-08-27 | 2019-01-11 | 江苏大学 | A kind of non-isolated grid-connected inverter circuit of type leakage current and control method altogether |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101707442A (en) * | 2009-11-16 | 2010-05-12 | 浙江大学 | Transformer-free inverter |
| CN104578856A (en) * | 2014-12-23 | 2015-04-29 | 燕山大学 | Single-stage non-isolated non-electrolytic-capacitor double-Zeta inverter |
| CN105978388A (en) * | 2016-06-02 | 2016-09-28 | 燕山大学 | Single-phase voltage boosting-reducing type photovoltaic inverter capable of inhibiting current leakage and control method thereof |
| CN106374770A (en) * | 2016-10-28 | 2017-02-01 | 燕山大学 | Input and output common-ground boost-buck photovoltaic grid-connected inverter and control method thereof |
-
2017
- 2017-07-18 CN CN201710587318.8A patent/CN107147319B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101707442A (en) * | 2009-11-16 | 2010-05-12 | 浙江大学 | Transformer-free inverter |
| CN104578856A (en) * | 2014-12-23 | 2015-04-29 | 燕山大学 | Single-stage non-isolated non-electrolytic-capacitor double-Zeta inverter |
| CN105978388A (en) * | 2016-06-02 | 2016-09-28 | 燕山大学 | Single-phase voltage boosting-reducing type photovoltaic inverter capable of inhibiting current leakage and control method thereof |
| CN106374770A (en) * | 2016-10-28 | 2017-02-01 | 燕山大学 | Input and output common-ground boost-buck photovoltaic grid-connected inverter and control method thereof |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107947617A (en) * | 2017-10-23 | 2018-04-20 | 胡炎申 | A kind of hybrid switch single-phase inverter |
| CN109194175A (en) * | 2018-08-27 | 2019-01-11 | 江苏大学 | A kind of non-isolated grid-connected inverter circuit of type leakage current and control method altogether |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107147319B (en) | 2020-07-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101980409B (en) | Grid-connected photovoltaic inverter | |
| CN104270022B (en) | Photovoltaic grid connected inversion circuit, switch control circuit and control method | |
| CN103051233A (en) | Non-isolated single-phase photovoltaic grid-connected inverter and on-off control timing sequence thereof | |
| CN104485832A (en) | Photovoltaic high-frequency chain grid-connected inverter capable of restraining input low-frequency current ripples | |
| CN107086600A (en) | A kind of solar energy power generating three phase full bridge grid-connected inverting system | |
| CN110323959A (en) | It can inhibit the single-phase inverter and its control method of secondary ripple wave and common mode leakage current | |
| CN109755960A (en) | A kind of nine electrical level inverter topological structure of single-phase grid-connected switching capacity | |
| CN108448918B (en) | A kind of single-phase grid-connected photovoltaic DC-to-AC converter of transless | |
| CN104269914A (en) | Wind-solar complementary control and inversion integrated machine | |
| CN203747686U (en) | Single-phase mixed three-level grid-connected inverter | |
| Tian et al. | A single-phase transformerless common-ground type PV inverter with active power decoupling | |
| CN207251220U (en) | A kind of solar energy power generating three phase full bridge grid-connected inverting system | |
| CN109194175A (en) | A kind of non-isolated grid-connected inverter circuit of type leakage current and control method altogether | |
| CN106452144B (en) | A kind of buck-boost type three-level inverter based on Zeta | |
| CN109167525B (en) | Novel non-isolated five-level inverter | |
| CN107147319A (en) | Non-isolated grid-connected inverter, grid-connected photovoltaic system and control method | |
| CN110198131A (en) | It is a kind of can total power factor operation without the non-isolated inverter of switching loss type | |
| CN104158427B (en) | Single-phase transless isolated form Z source photovoltaic combining inverter and modulator approach | |
| CN110071652A (en) | A kind of low-leakage current five switchs non-isolated single-phase photovoltaic grid-connected inverter and grid-connected system | |
| Lai | A single-stage grid-connected pv micro-inverter based on interleaved flyback converter topology | |
| CN104167946A (en) | Midpoint clamping type single-phase non-isolated photovoltaic inverter main circuit topology with follow current switch | |
| CN108809130A (en) | The modulator approach of the sources Semi-Z single-phase inverter | |
| CN104811076A (en) | Inverter and control method thereof | |
| CN114844384A (en) | Five-level grid-connected inverter structure, inverter and photovoltaic power system | |
| CN103915858B (en) | Photovoltaic micro-inverter power generation system based on multi-winding high-frequency magnetic coupling system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| TA01 | Transfer of patent application right | ||
| TA01 | Transfer of patent application right |
Effective date of registration: 20200115 Address after: 233100 Mount Huangshan Avenue, Bengbu, Anhui, 1501 (Longhu campus) Applicant after: Anhui Science and Technology University Address before: 232001 Anhui province Huainan Taifeng Street No. 168 Applicant before: Anhui University Of Science And Technology |
|
| GR01 | Patent grant | ||
| GR01 | Patent grant |