CN106655255A - Method of photovoltaic energy storage inverter grid-connecting, grid-disconnecting, and switching between the two as well as circuit - Google Patents
Method of photovoltaic energy storage inverter grid-connecting, grid-disconnecting, and switching between the two as well as circuit Download PDFInfo
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- CN106655255A CN106655255A CN201610963967.9A CN201610963967A CN106655255A CN 106655255 A CN106655255 A CN 106655255A CN 201610963967 A CN201610963967 A CN 201610963967A CN 106655255 A CN106655255 A CN 106655255A
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Classifications
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- H02J3/385—
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- 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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/388—Islanding, i.e. disconnection of local power supply from the network
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
Abstract
The invention provides a method of photovoltaic energy storage inverter grid-connecting, grid-disconnecting, and switching between the two as well as circuit. The grid-connecting and grid-disconnecting switching circuit comprises a capacitance filtering circuit C1 and capacitance filtering circuit C2, controllable switches referred as K1 to K6. The grid side of the PCS is in cascade connection with the series-connected circuit of K1 and C1, the K3, C2 and K4 sequentially before being divided into two branch circuits wherein the first branch circuit is connected to the power grid and the second branch circuit is connected to a local load; the coils of K5 and K2 are in series connection before being connected to the two ends of the C2; the normally closed contact of the K5 is in series-connection with the coils of the K6 and is then connected between the zero line and the live line of the first branch circuit; the normally opened contact of the K6 is in series-connection with the live line of the first branch circuit. The grid-connecting and grid-disconnecting switching method of the invention strictly limits the starting and ending periods of a PCS as well as the action time sequences of various controllable switches in the grid-connecting and grid-disconnecting switching circuit when fault occurs to the power grid so as to ensure that in the process of grid-connecting and grid-disconnecting, no components are damaged and that the switching between the grid-connecting mode and the grid-disconnecting mode becomes safe and reliable.
Description
Technical field
The present invention relates to light storage technical field of power generation, more particularly, it relates to photovoltaic energy storage inverter and/off-network, from/
Grid-connected changing method and circuit.
Background technology
Photovoltaic energy storage inverter has two kinds of typical operational modes, grid-connect mode and off-network pattern.When electrical network is normal,
Photovoltaic energy storage invertor operation is in grid-connect mode；When electrical network is abnormal, photovoltaic energy storage inverter is switched under off-network pattern and runs,
Switch back into grid-connect mode again when power system restoration is normal.
How to ensure the security reliability switched between grid-connect mode and off-network pattern, be the target that this area is pursued always.
The content of the invention
In view of this, the invention provides photovoltaic energy storage inverter and/off-network, off-grid grid-connected changing method and circuit, with
Ensure the security reliability switched between grid-connect mode and off-network pattern.
A kind of photovoltaic energy storage inverter and/off-network changing method, be applied to simultaneously/off-network switching circuit；It is described simultaneously/off-network
Switching circuit include the first capacitor filter, the second capacitor filter, the first gate-controlled switch, the second gate-controlled switch, the 3rd
Gate-controlled switch, the 4th gate-controlled switch, the 5th gate-controlled switch and the 6th gate-controlled switch, wherein：
The net side of photovoltaic energy storage inverter cascades successively first gate-controlled switch with first capacitor filter
It is divided into two articles after series arm, the 3rd gate-controlled switch, second capacitor filter and the 4th gate-controlled switch
Branch road, tie point is connected to electrical network, and the second branch road is connected to local load；
The coil of the 5th gate-controlled switch is connected with second gate-controlled switch and is followed by second capacitor filtering electricity
Road two ends；
The normally-closed contact of the 5th gate-controlled switch is connected with the coil of the 6th gate-controlled switch and is followed by described first
Between the zero line and live wire of branch road；
The normally opened contact of the 6th gate-controlled switch is connected on the live wire of the tie point；
It is described simultaneously/off-network changing method, including：
When photovoltaic energy storage invertor operation is in grid-connect mode, first gate-controlled switch and described second is kept controllable to open
Shut-off is opened, the 3rd gate-controlled switch and the 4th gate-controlled switch are closed；
Judge whether electrical network breaks down；
When judging to obtain grid collapses, control photovoltaic energy storage inverter is shut down, and is disconnected the described 3rd and controllable opened
Close and the 4th gate-controlled switch；
First gate-controlled switch and the 3rd gate-controlled switch are closed, and controls photovoltaic energy storage inverter startup；
At the inverter voltage zero crossing moment after inverter voltage reaches photovoltaic energy storage inverter rated output voltage, close institute
State the second gate-controlled switch；
Photovoltaic voltage is adjusted to maximum power point, then controllable is opened in inverter voltage zero crossing moment closure the described 4th
Close.
Wherein, it is described to judge whether electrical network breaks down, at least include：Based on the first criterion and/or Second Criterion, judge
Whether isolated island failure there is；
Specifically, first criterion, including：Line voltage is obtained, judges the line voltage for getting whether less than pre-
If value；If so, it is judged to isolated island failure；
The Second Criterion, including：Obtain the on off state of the 6th gate-controlled switch；Judge the 6th gate-controlled switch
Whether it is in off-state；If so, it is judged to isolated island failure.
Alternatively, it is described simultaneously/off-network switching circuit also includes：It is manual with what the coil of the 6th gate-controlled switch was in series
Switch, the hand switch is defaulted as closure state；
It is corresponding, it is described judge whether electrical network breaks down before, also include：Judging the on off state of the hand switch is
It is no for off-state；If so, perform the control photovoltaic energy storage inverter to shut down, and disconnect the 3rd gate-controlled switch and described
The step of four gate-controlled switches；If it is not, execution is described to judge the step of whether electrical network breaks down.
A kind of off-grid grid-connected changing method of photovoltaic energy storage inverter, is applied to off-grid grid-connected switching circuit；The off-grid grid-connected
Switching circuit include the first capacitor filter, the second capacitor filter, the first gate-controlled switch, the second gate-controlled switch, the 3rd
Gate-controlled switch, the 4th gate-controlled switch, the 5th gate-controlled switch and the 6th gate-controlled switch, wherein：
The net side of photovoltaic energy storage inverter cascades successively first gate-controlled switch with first capacitor filter
It is divided into two articles after series arm, the 3rd gate-controlled switch, second capacitor filter and the 4th gate-controlled switch
Branch road, tie point is connected to electrical network, and the second branch road is connected to local load；
The coil of the 5th gate-controlled switch is connected with second gate-controlled switch and is followed by second capacitor filtering electricity
Road two ends；
The normally-closed contact of the 5th gate-controlled switch is connected with the coil of the 6th gate-controlled switch and is followed by described first
Between the zero line and live wire of branch road；
The normally opened contact of the 6th gate-controlled switch is connected on the live wire of the tie point；
The off-grid grid-connected changing method, including：
When photovoltaic energy storage invertor operation is in off-network pattern, first gate-controlled switch, described second is kept controllable to open
Close, the 3rd gate-controlled switch and the 4th gate-controlled switch are closed；
Judge whether electrical network recovers normal；
If judgement obtains power system restoration normally, control photovoltaic energy storage inverter is shut down, disconnection the 3rd gate-controlled switch,
4th gate-controlled switch and second gate-controlled switch, and when the first capacitor filter self discharge is completed, break
Open first gate-controlled switch；
Control photovoltaic energy storage inverter startup, and close the 3rd gate-controlled switch and the 4th gate-controlled switch.
Alternatively, the off-grid grid-connected switching circuit also includes：It is manual with what the coil of the 6th gate-controlled switch was in series
Switch, the hand switch is defaulted as closure state；
Before the control photovoltaic energy storage inverter is shut down, also include：Judgement obtains the on off state of the hand switch
Closure state.
A kind of photovoltaic energy storage inverter and/off-network switching circuit, including main circuit and control unit；
The main circuit includes the first capacitor filter, the second capacitor filter, the first gate-controlled switch, second controllable
Switch, the 3rd gate-controlled switch, the 4th gate-controlled switch, the 5th gate-controlled switch and the 6th gate-controlled switch, wherein：Photovoltaic energy storage inverter
Net side cascade first gate-controlled switch and the series arm of first capacitor filter successively, the described 3rd controllable open
It is divided into two articles of branch roads after pass, second capacitor filter and the 4th gate-controlled switch, tie point is connected to electrical network,
Second branch road is connected to local load；The coil of the 5th gate-controlled switch is connected with second gate-controlled switch and is followed by described
Second capacitor filter two ends；After the normally-closed contact of the 5th gate-controlled switch is connected with the coil of the 6th gate-controlled switch
It is connected between the zero line of the tie point and live wire；The normally opened contact of the 6th gate-controlled switch is connected on the tie point
Live wire on；
Described control unit, for when photovoltaic energy storage invertor operation is in grid-connect mode, keeps described first controllable to open
Close and second gate-controlled switch disconnects, the 3rd gate-controlled switch and the 4th gate-controlled switch are closed；Whether judge electrical network
Break down；When judging to obtain grid collapses, control photovoltaic energy storage inverter is shut down, and is disconnected the described 3rd and controllable opened
Close and the 4th gate-controlled switch；First gate-controlled switch and the 3rd gate-controlled switch are closed, and it is inverse to control photovoltaic energy storage
Become device to start；Inverter voltage zero crossing moment after inverter voltage reaches photovoltaic energy storage inverter rated output voltage, closure
Second gate-controlled switch；Photovoltaic voltage is adjusted to maximum power point, then in inverter voltage zero crossing moment closure described the
Four gate-controlled switches.
Wherein, described control unit judges whether electrical network breaks down, and at least includes：Based on the first criterion and/or second
Criterion, judges whether isolated island failure；
Specifically, first criterion, including：Line voltage is obtained, judges the line voltage for getting whether less than pre-
If value；If so, it is judged to isolated island failure；
The Second Criterion, including：Obtain the on off state of the 6th gate-controlled switch；Judge the 6th gate-controlled switch
Whether it is in off-state；If so, it is judged to isolated island failure.
Alternatively, the main circuit also includes：The hand switch being in series with the coil of the 6th gate-controlled switch, it is described
Hand switch is defaulted as closure state；
It is corresponding, before described control unit judges whether electrical network breaks down, it is additionally operable to judge opening for the hand switch
Whether off status is off-state；If so, perform the control photovoltaic energy storage inverter to shut down, and disconnect the described 3rd and controllable open
The step of closing with four gate-controlled switch；If it is not, execution is described to judge the step of whether electrical network breaks down.
A kind of off-grid grid-connected switching circuit of photovoltaic energy storage inverter, including main circuit and control unit；
The main circuit includes the first capacitor filter, the second capacitor filter, the first gate-controlled switch, second controllable
Switch, the 3rd gate-controlled switch, the 4th gate-controlled switch, the 5th gate-controlled switch and the 6th gate-controlled switch, wherein：Photovoltaic energy storage inverter
Net side cascade first gate-controlled switch and the series arm of first capacitor filter successively, the described 3rd controllable open
It is divided into two articles of branch roads after pass, second capacitor filter and the 4th gate-controlled switch, tie point is connected to electrical network,
Second branch road is connected to local load；The coil of the 5th gate-controlled switch is connected with second gate-controlled switch and is followed by described
Second capacitor filter two ends；After the normally-closed contact of the 5th gate-controlled switch is connected with the coil of the 6th gate-controlled switch
It is connected between the zero line of the tie point and live wire；The normally opened contact of the 6th gate-controlled switch is connected on the tie point
Live wire on；
Described control unit, for when photovoltaic energy storage invertor operation is in off-network pattern, keeps described first controllable to open
Pass, second gate-controlled switch, the 3rd gate-controlled switch and the 4th gate-controlled switch closure；Judge whether electrical network recovers just
Often；If judging to obtain power system restoration normal, control photovoltaic energy storage inverter is shut down, and disconnects the 3rd gate-controlled switch, described
4th gate-controlled switch and second gate-controlled switch, and when the first capacitor filter self discharge is completed, disconnect institute
State the first gate-controlled switch；Control photovoltaic energy storage inverter startup, and close the 3rd gate-controlled switch and the described 4th and controllable open
Close.
Alternatively, the main circuit also includes：The hand switch being in series with the coil of the 6th gate-controlled switch, it is described
Hand switch is defaulted as closure state；
It is corresponding, before described control unit control photovoltaic energy storage inverter is shut down, it is additionally operable to judgement and obtains described opening manually
The on off state of pass is closure state.
It can be seen from above-mentioned technical scheme that, it is disclosed by the invention simultaneously/off-network changing method be applied to simultaneously/off-network switching
Circuit, the simultaneously/off-network changing method when electric network fault is detected, start and stop moment to PCS and it is described simultaneously/off-network switching electricity
The action sequence of each gate-controlled switch has carried out strict restriction in road so that first enter stopped status by grid-connect mode in PCS, then by
Be not in device failure phenomenon during stopped status enters off-network pattern, so as to ensure that the safety of simultaneously/off-network switching
Reliability.
Description of the drawings
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
The accompanying drawing to be used needed for having technology description is briefly described, it should be apparent that, drawings in the following description are only this
Some embodiments of invention, for those of ordinary skill in the art, on the premise of not paying creative work, can be with
Other accompanying drawings are obtained according to these accompanying drawings.
Fig. 1 a be disclosed in the embodiment of the present invention it is a kind of simultaneously/the main circuit topological structure schematic diagram of off-network switching circuit；
Fig. 1 b be disclosed in the embodiment of the present invention it is a kind of simultaneously/off-network changing method flow chart；
Fig. 2 a are the main circuit topological structure schematic diagram of another simultaneously/off-network switching circuit disclosed in the embodiment of the present invention；
Fig. 2 b are another simultaneously/off-network changing method flow chart disclosed in the embodiment of the present invention；
Fig. 3 is a kind of off-grid grid-connected changing method flow chart disclosed in the embodiment of the present invention；
Fig. 4 is another off-grid grid-connected changing method flow chart disclosed in the embodiment of the present invention.
Specific embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete
Site preparation is described, it is clear that described embodiment is only a part of embodiment of the invention, rather than the embodiment of whole.It is based on
Embodiment in the present invention, it is every other that those of ordinary skill in the art are obtained under the premise of creative work is not made
Embodiment, belongs to the scope of protection of the invention.
The embodiment of the invention discloses a kind of photovoltaic energy storage inverter (hereinafter referred to as PCS) and/off-network changing method, with
Ensure the security reliability of simultaneously/off-network pattern switching.
It is described simultaneously/off-network changing method is applied to simultaneously/off-network switching circuit, as shown in Figure 1a, it is described simultaneously/off-network switching electricity
Road include the first capacitor filter C1, the second capacitor filter C2, the first gate-controlled switch K1, the second gate-controlled switch K2, the
Three gate-controlled switch K3, the 4th gate-controlled switch K4, the 5th gate-controlled switch K5 and the 6th gate-controlled switch K6, specifically：
The net side of PCS to cascade be divided into two branch roads, tie point after series arm, K3, C2 and K4 of K1 and C1 successively
Electrical network is connected to, the second branch road is connected to local load；
The coil of K5 is connected with K2 and is followed by C2 two ends；
The normally-closed contact of K5 is connected with the coil of K6 and is followed by between the zero line and live wire of the tie point (in Fig. 1 a
In, L, N and PE represent respectively zero line, live wire and ground wire)；
The normally opened contact of K6 is connected on the live wire of the tie point.
Referring to Fig. 1 b, it is described simultaneously/off-network changing method, including：
Step S01：When PCS runs on grid-connect mode, K1 and K2 disconnections, K3 and K4 closures are kept.
Off-network pattern is compared, the filter capacitor capacity needed under grid-connect mode is less, so the present embodiment is in off-network pattern
Lower closure K1 so that C1 and C2 accesses circuit simultaneously；K1 is disconnected under grid-connect mode so that C2 accesses circuit, C1 and do not access electricity
Road.
Keep K2 to disconnect, K3 and K4 is closed, be the essential condition that PCS runs on grid-connect mode, make a concrete analysis of as follows：K2 breaks
After opening, the coil of K5 must not be electric, so the normally-closed contact of K5 is in closure state；After the normally-closed contact of K5, K3 and K4 are closed, K6
Coil obtain electric by line voltage, while the net side output current of PCS through C2 filtering after by second branch road flow into this
Ground load；The coil of K6 obtain it is electric after, the normally opened contact of K6 closure, now the net side output current of PCS pass through after C2 filtering
The tie point flows into electrical network, it is achieved thereby that PCS is incorporated into the power networks.
It is with 0,1 disconnection, the closure state for representing gate-controlled switch respectively, then each controllable to open when PCS runs under grid-connect mode
The initial switch state of pass is as shown in table 1.
The initial switch state of each gate-controlled switches of table 1-
| Gate-controlled switch is numbered | Initial switch state |
| K1 | 0 |
| K2 | 0 |
| K3 | 1 |
| K4 | 1 |
| K5 | 1 |
| K6 | 1 |
Step S02：Judge whether electrical network breaks down；If judgement obtains grid collapses, into step S03；Otherwise,
Return to step S02.
Isolated island failure is one of modal electric network fault.It is corresponding, it is described to judge whether electrical network breaks down, at least wrap
Include：Judge whether isolated island failure.
The present embodiment carries out isolated island breakdown judge based on the first criterion and/or Second Criterion.Compared to being sentenced based on substance
According to isolated island breakdown judge, although the complexity of calculating can be increased based on the isolated island breakdown judge of dual criterion, improve and sentence
The reliability of disconnected result.
Wherein, first criterion, including：Obtain line voltage Vgrid, judge VgridWhether preset value is less than, is if so, sentenced
It is set to generation isolated island failure.
The preset value determines according to the criterion of isolated island failure.Such as, in practical application with Vgrid＜ 50VAC
As the standard for judging isolated island failure, i.e., regarding Vgrid＜ 50VAC flow through for grid entry point no current, then the preset value just sets
For 50VAC.
The Second Criterion, including：Obtain the on off state of K6；Judge K6 whether in off-state；If so, it is judged to send out
Raw isolated island failure.
After generation isolated island failure, the coil of K6 can not again from line voltage power taking.After the coil losing electricity of K6, the normally opened of K6 touches
Point reverts to off-state.So by judging that the on off state of K6 may determine that whether isolated island failure.
Step S03：Control PCS shuts down, and disconnects K3 and K4.
To meet the requirement of security legislation, the net side of inverter needs to connect two relays, and effect is in inverter not work
Disconnect when work or failure, to separate the connection of inverter and electrical network.K3 and K4 in the present embodiment exactly the two relays.
After PCS shuts down, the net side output voltage (i.e. inverter voltage) of PCS is zero, is stopped so as to the PCS for running on grid-connect mode has been switched to
Machine state.
Next, needing to enter under off-network pattern and transport using step S04～PCS of the step S06 control in stopped status
OK.When PCS runs on off-network pattern, K1, K2, K3 and K4 need to be kept to close, but in order to safe and reliable is switched to off-network pattern,
There are timing requirements to the switching action of each gate-controlled switch, be described in detail below.
Step S04：Closure K1 and K3, and control PCS startups.
After PCS starts, inverter voltage delays liter by 0V；Closure K1, is the output in order to improve PCS under off-network state
Performance, while K3 to be switched to the on off state for needing to meet when PCS runs on off-network pattern.
Step S05：PCS rated output voltages are reached in inverter voltage (be designated as Ve) after the inverter voltage zero crossing moment close
Close K2.
Closure K2, is that in order that inverter voltage is applied to the coil two ends of K5, the coil for making K5 obtains electric.The coil of K5 obtains electric
Afterwards, the normally-closed contact of K5 disconnects, and the coil losing electricity of K6, the normally opened contact of K6 reverts to off-state.
Why the moment of closure K2 selects to reach V in inverter voltageeAt the inverter voltage zero crossing moment afterwards, it is because：
Inverter voltage is raised to V from 0V is sloweAfterwards, its waveform is that amplitude is VeSine wave, if inscribed when inverter voltage instantaneous value is higher
K2 is closed, then higher instantaneous voltage can be applied to the coil two ends of K5, and the coil of K5 is impacted；And select in inversion electricity
Pressing through zero point moment closure K2 can then avoid this problem.
Step S06：Photovoltaic voltage is adjusted to maximum power point, then K4 is closed at the inverter voltage zero crossing moment, so as to
Safely and reliably it has been switched to off-network pattern.
Photovoltaic voltage is adjusted to maximum power point, PCS can fill by the accumulator for accessing PCS of peak power output
Electricity, so after K4 is closed, access PCS photovoltaic cell and accumulator can quick output, make PCS reach maximum belt
Loading capability.Closure K4 moment, why be selected in the inverter voltage zero crossing moment, be in order to avoid inverter voltage instantaneous value compared with
K4 is closed when high, local load is impacted.
It is with 0,1 disconnection, the closure state for representing gate-controlled switch respectively, then each controllable to open when PCS runs under off-network pattern
The initial switch state of pass is as shown in table 2.
The initial switch state of each gate-controlled switches of table 2-
| Gate-controlled switch is numbered | Initial switch state |
| K1 | 1 |
| K2 | 1 |
| K3 | 1 |
| K4 | 1 |
| K5 | 0 |
| K6 | 0 |
From the foregoing, it will be observed that present embodiment discloses a kind of be applied to simultaneously/off-network switching circuit and/off-network changing method, should
And/off-network changing method is when electric network fault is detected, start and stop moment to PCS and it is described simultaneously/off-network switching circuit in it is each
The action sequence of gate-controlled switch has carried out strict restriction so that first enter stopped status by grid-connect mode in PCS, then by shutdown shape
Be not in device failure phenomenon during state enters off-network pattern, so as to ensure that the safe and reliable of simultaneously/off-network switching
Property.
Additionally, when electrical network does not break down and PCS runs on grid-connect mode, if staff wants to force
PCS is switched under off-network pattern and is run, then following can carry out reality by doing on the basis of scheme shown in Fig. 1 a- Fig. 1 b
It is existing.
Simultaneously/off-network switching circuit also includes shown in Fig. 1 a：The hand switch B1 being in series with the coil of K6 is (such as Fig. 2 a institutes
Show), B1 is defaulted as closure state.Run under staff wishes to be switched to PCS off-network pattern, can manually disconnect B1.
After B1 disconnects, the coil losing electricity of K6, the normally opened contact of K6 disconnects.
It is corresponding, before step S02 shown in Fig. 1 b is performed, also including (referring to Fig. 2 b)：Step S011：Judge the switch shape of B1
Whether state is off-state, if so, illustrates that staff is disconnected manually B1, is now directly entered step S03；If it is not, performing
Step S02.
The embodiment of the invention also discloses a kind of off-grid grid-connected changing method, to ensure that the safety of off-grid grid-connected pattern switching can
By property.
The off-grid grid-connected changing method is applied to off-grid grid-connected switching circuit, shown in the off-grid grid-connected switching circuit and Fig. 1 a
The main circuit topological structure of off-grid grid-connected switching circuit is identical, repeats no more.
Referring to Fig. 3, the off-grid grid-connected changing method, including：
Step S01：When PCS runs on off-network pattern, K1, K2, K3 and K4 closure is kept.
After K1, K2, K3 and K4 are closed, the normally-closed contact of K5 is in off-state with the normally opened contact of K6.
Step S02：Judge whether electrical network recovers normal；If so, step S03 is entered；If it is not, return to step S02；
Step S03：Control PCS shuts down, and disconnects K3, K4 and K2, and when C1 self discharges are completed, disconnects K1.
After PCS shuts down, the coil of K5 can not obtain electric by inverter voltage again, the normally-closed contact closure of K5；The normally-closed contact of K5
After closure, the coil of K6 obtains electric by line voltage, the normally opened contact closure of K6.
PCS shut down, K4 disconnect after, C1 starts self discharge (mainly using PCS internal components carries out self discharge), when C1 it is extensive
When being zero-voltage state again, you can disconnect the self discharge loop that K1 carrys out disjunction C1.K2 can be simultaneously switched off with K4, it is also possible to K1
Simultaneously switch off, do not limit to.
Step S04：Control PCS starts, and closes K3 and K4, has thus switched to grid-connect mode, now each gate-controlled switch
Initial switch state reverted to as shown in table 1.
The purpose of scheme shown in Fig. 3 is, by the state of PCS, the state of C1 and each gate-controlled switch under off-network pattern
On off state switches back into the initial operating state under grid-connect mode.
Additionally, the embodiment of the invention also discloses another kind of off-grid grid-connected changing method, the off-grid grid-connected changing method application
In another kind of off-grid grid-connected switching circuit, the off-grid grid-connected switching circuit is opened up with the main circuit of off-grid grid-connected switching circuit shown in Fig. 2 a
Flutter structure identical, repeat no more.
Referring to Fig. 4, the off-grid grid-connected changing method, including：
Step S01：When PCS runs on off-network pattern, K1, K2, K3 and K4 closure is kept.
Step S02：Judge whether electrical network recovers normal；If so, step S03 is entered；If it is not, return to step S02；
Step S03：Whether the on off state for judging B1 is closure state, if it is not, explanation staff is just forcing PCS to run
In off-network pattern, EP (end of program)；If so, step S04 is entered.
Step S04：Control PCS shuts down, and disconnects K3 and K4 and K2；And when C1 and C2 self discharges are completed, disconnect K1.
Step S05：Control PCS starts, and closes K3 and K4, has thus switched to grid-connect mode.
Scheme shown in Fig. 4 is with the difference part of scheme shown in Fig. 3, due to drawing in corresponding off-grid grid-connected switching circuit
B1 is entered, so increased step S03 on off-grid grid-connected changing method.
Correspondence said method, the embodiment of the invention also discloses circuits below.
The embodiment of the invention discloses a kind of photovoltaic energy storage inverter and/off-network switching circuit, including main circuit and control
Unit processed, wherein：
The composition and its annexation of the main circuit as shown in Figure 1a, is repeated no more；
Described control unit is used for, and when PCS runs on grid-connect mode, keeps K1 and K2 disconnections, K3 and K4 closures；Judge
Whether electrical network breaks down；If judgement obtains grid collapses, control PCS shuts down, and disconnects K3 and K4；Closure K1 and K3,
And control PCS startup；Inverter voltage zero crossing moment closure K2 after inverter voltage reaches PCS rated output voltages；By light
Volt voltage-regulation closes K4 to maximum power point, then at the inverter voltage zero crossing moment.
Wherein, described control unit judges whether electrical network breaks down, and at least includes：Based on the first criterion and/or second
Criterion, judges whether isolated island failure.Wherein, first criterion, including：Obtain line voltage Vgrid, judge VgridWhether
Less than preset value, if so, it is judged to isolated island failure.The Second Criterion, including：Obtain the on off state of K6；Judge K6
Whether it is in off-state；If so, it is judged to isolated island failure.
Optionally, the main circuit also includes：The hand switch B1 (as shown in Figure 2 a) being in series with the coil of K6, B1 write from memory
Think closure state.Corresponding, described control unit is additionally operable to judge the switch shape of B1 before judging whether electrical network breaks down
Whether state is off-state, the step of if so, jumping into the control PCS and shut down, and disconnect K3 and K4；If it is not, sentencing described in performing
The step of whether power-off net breaks down.
The embodiment of the invention also discloses a kind of off-grid grid-connected switching circuit of photovoltaic energy storage inverter, including main circuit and
Control unit, wherein：
The composition and its annexation of the main circuit as shown in Figure 1a, is repeated no more；
Described control unit is used for, and when PCS runs on off-network pattern, keeps K1, K2, K3 and K4 closure；Judge electrical network
Whether recover normal；If so, control PCS to shut down, disconnect K3, K4 and K2, and when C1 self discharges are completed, disconnect K1；Control
PCS starts, and closes K3 and K4.
Optionally, the main circuit also includes：The hand switch B1 (as shown in Figure 2 a) being in series with the coil of K6, B1 write from memory
Think closure state.It is corresponding, before described control unit control photovoltaic energy storage inverter is shut down, it is additionally operable to judge to obtain opening for B1
Off status is closure state.
In sum, it is disclosed by the invention simultaneously/off-network changing method is applied to simultaneously/off-network switching circuit, the simultaneously/off-network is cut
Method is changed when electric network fault is detected, start and stop moment to PCS and it is described simultaneously/off-network switching circuit in each gate-controlled switch
Action sequence has carried out strict restriction so that first enters stopped status by grid-connect mode in PCS, then enters off-network by stopped status
Be not in device failure phenomenon during pattern, so as to ensure that the security reliability of simultaneously/off-network switching.
Each embodiment is described by the way of progressive in this specification, and what each embodiment was stressed is and other
The difference of embodiment, between each embodiment identical similar portion mutually referring to.For switching disclosed in embodiment
For circuit, because it is corresponded to the method disclosed in Example, so description is fairly simple, related part is referring to method portion
Defend oneself bright.
The foregoing description of the disclosed embodiments, enables professional and technical personnel in the field to realize or using the present invention.
Various modifications to these embodiments will be apparent for those skilled in the art, as defined herein
General Principle can in other embodiments be realized in the case of the spirit or scope without departing from the embodiment of the present invention.Therefore,
The embodiment of the present invention is not intended to be limited to the embodiments shown herein, and be to fit to principles disclosed herein and
The consistent most wide scope of features of novelty.
Claims (10)
1. a kind of photovoltaic energy storage inverter and/off-network changing method, it is characterised in that be applied to simultaneously/off-network switching circuit；Institute
Simultaneously/off-network switching circuit is stated including the first capacitor filter, the second capacitor filter, the first gate-controlled switch, second controllable
Switch, the 3rd gate-controlled switch, the 4th gate-controlled switch, the 5th gate-controlled switch and the 6th gate-controlled switch, wherein：
The net side of photovoltaic energy storage inverter cascades successively connecting for first gate-controlled switch and first capacitor filter
It is divided into two articles of branch roads after branch road, the 3rd gate-controlled switch, second capacitor filter and the 4th gate-controlled switch,
Tie point is connected to electrical network, and the second branch road is connected to local load；
The coil of the 5th gate-controlled switch is connected with second gate-controlled switch and is followed by second capacitor filter two
End；
The normally-closed contact of the 5th gate-controlled switch is connected with the coil of the 6th gate-controlled switch and is followed by the tie point
Zero line and live wire between；
The normally opened contact of the 6th gate-controlled switch is connected on the live wire of the tie point；
It is described simultaneously/off-network changing method, including：
When photovoltaic energy storage invertor operation is in grid-connect mode, keep first gate-controlled switch and second gate-controlled switch disconnected
Open, the 3rd gate-controlled switch and the 4th gate-controlled switch are closed；
Judge whether electrical network breaks down；
When judging to obtain grid collapses, control photovoltaic energy storage inverter is shut down, and disconnect the 3rd gate-controlled switch and
4th gate-controlled switch；
First gate-controlled switch and the 3rd gate-controlled switch are closed, and controls photovoltaic energy storage inverter startup；
At the inverter voltage zero crossing moment after inverter voltage reaches photovoltaic energy storage inverter rated output voltage, close described the
Two gate-controlled switches；
Photovoltaic voltage is adjusted to maximum power point, then the 4th gate-controlled switch is closed at the inverter voltage zero crossing moment.
2. it is according to claim 1 simultaneously/off-network changing method, it is characterised in that it is described to judge whether electrical network breaks down,
At least include：Based on the first criterion and/or Second Criterion, judge whether isolated island failure；
Wherein, first criterion, including：Line voltage is obtained, judges the line voltage for getting whether less than preset value；If
It is to be judged to isolated island failure；
The Second Criterion, including：Obtain the on off state of the 6th gate-controlled switch；Whether judge the 6th gate-controlled switch
In off-state；If so, it is judged to isolated island failure.
3. it is according to claim 1 simultaneously/off-network changing method, it is characterised in that it is described simultaneously/off-network switching circuit also wraps
Include：The hand switch being in series with the coil of the 6th gate-controlled switch, the hand switch is defaulted as closure state；
It is corresponding, it is described judge whether electrical network breaks down before, also include：Whether the on off state for judging the hand switch be
Off-state；If so, perform the control photovoltaic energy storage inverter to shut down, and disconnect the 3rd gate-controlled switch and the described 4th
The step of gate-controlled switch；If it is not, execution is described to judge the step of whether electrical network breaks down.
4. a kind of off-grid grid-connected changing method of photovoltaic energy storage inverter, it is characterised in that be applied to off-grid grid-connected switching circuit；Institute
Off-grid grid-connected switching circuit is stated including the first capacitor filter, the second capacitor filter, the first gate-controlled switch, second controllable
Switch, the 3rd gate-controlled switch, the 4th gate-controlled switch, the 5th gate-controlled switch and the 6th gate-controlled switch, wherein：
The net side of photovoltaic energy storage inverter cascades successively connecting for first gate-controlled switch and first capacitor filter
It is divided into two articles of branch roads after branch road, the 3rd gate-controlled switch, second capacitor filter and the 4th gate-controlled switch,
Tie point is connected to electrical network, and the second branch road is connected to local load；
The coil of the 5th gate-controlled switch is connected with second gate-controlled switch and is followed by second capacitor filter two
End；
The normally-closed contact of the 5th gate-controlled switch is connected with the coil of the 6th gate-controlled switch and is followed by the tie point
Zero line and live wire between；
The normally opened contact of the 6th gate-controlled switch is connected on the live wire of the tie point；
The off-grid grid-connected changing method, including：
When photovoltaic energy storage invertor operation is in off-network pattern, first gate-controlled switch, second gate-controlled switch, institute are kept
State the 3rd gate-controlled switch and the 4th gate-controlled switch closure；
Judge whether electrical network recovers normal；
If judging to obtain power system restoration normal, control photovoltaic energy storage inverter is shut down, and disconnects the 3rd gate-controlled switch, described
4th gate-controlled switch and second gate-controlled switch, and when the first capacitor filter self discharge is completed, disconnect institute
State the first gate-controlled switch；
Control photovoltaic energy storage inverter startup, and close the 3rd gate-controlled switch and the 4th gate-controlled switch.
5. off-grid grid-connected changing method according to claim 4, it is characterised in that the off-grid grid-connected switching circuit is also wrapped
Include：The hand switch being in series with the coil of the 6th gate-controlled switch, the hand switch is defaulted as closure state；
Before the control photovoltaic energy storage inverter is shut down, also include：Judge the on off state for obtaining the hand switch to close
State.
6. a kind of photovoltaic energy storage inverter and/off-network switching circuit, it is characterised in that including main circuit and control unit；
The main circuit includes that the first capacitor filter, the second capacitor filter, the first gate-controlled switch, second controllable open
Pass, the 3rd gate-controlled switch, the 4th gate-controlled switch, the 5th gate-controlled switch and the 6th gate-controlled switch, wherein：Photovoltaic energy storage inverter
Net side cascades successively first gate-controlled switch and the series arm of first capacitor filter, the described 3rd controllable opens
It is divided into two articles of branch roads after pass, second capacitor filter and the 4th gate-controlled switch, tie point is connected to electrical network,
Second branch road is connected to local load；The coil of the 5th gate-controlled switch is connected with second gate-controlled switch and is followed by described
Second capacitor filter two ends；After the normally-closed contact of the 5th gate-controlled switch is connected with the coil of the 6th gate-controlled switch
It is connected between the zero line of the tie point and live wire；The normally opened contact of the 6th gate-controlled switch is connected on the tie point
Live wire on；
Described control unit, for when photovoltaic energy storage invertor operation is in grid-connect mode, keep first gate-controlled switch and
Second gate-controlled switch disconnects, the 3rd gate-controlled switch and the 4th gate-controlled switch are closed；Judge whether electrical network occurs
Failure；When judging to obtain grid collapses, control photovoltaic energy storage inverter is shut down, and disconnect the 3rd gate-controlled switch and
4th gate-controlled switch；First gate-controlled switch and the 3rd gate-controlled switch are closed, and controls photovoltaic energy storage inverter
Start；Inverter voltage zero crossing moment after inverter voltage reaches photovoltaic energy storage inverter rated output voltage, closure is described
Second gate-controlled switch；Photovoltaic voltage is adjusted to maximum power point, then can in inverter voltage zero crossing moment closure the described 4th
Control switch.
7. it is according to claim 6 simultaneously/off-network switching circuit, it is characterised in that whether described control unit judges electrical network
Break down, at least include：Based on the first criterion and/or Second Criterion, judge whether isolated island failure；
Wherein, first criterion, including：Line voltage is obtained, judges the line voltage for getting whether less than preset value；If
It is to be judged to isolated island failure；
The Second Criterion, including：Obtain the on off state of the 6th gate-controlled switch；Whether judge the 6th gate-controlled switch
In off-state；If so, it is judged to isolated island failure.
8. it is according to claim 6 simultaneously/off-network switching circuit, it is characterised in that the main circuit also includes：With described
The hand switch that the coil of six gate-controlled switches is in series, the hand switch is defaulted as closure state；
It is corresponding, before described control unit judges whether electrical network breaks down, it is additionally operable to judge the switch shape of the hand switch
Whether state is off-state；If so, perform the control photovoltaic energy storage inverter to shut down, and disconnect the 3rd gate-controlled switch and
The step of four gate-controlled switch；If it is not, execution is described to judge the step of whether electrical network breaks down.
9. a kind of off-grid grid-connected switching circuit of photovoltaic energy storage inverter, it is characterised in that including main circuit and control unit；
The main circuit includes that the first capacitor filter, the second capacitor filter, the first gate-controlled switch, second controllable open
Pass, the 3rd gate-controlled switch, the 4th gate-controlled switch, the 5th gate-controlled switch and the 6th gate-controlled switch, wherein：Photovoltaic energy storage inverter
Net side cascades successively first gate-controlled switch and the series arm of first capacitor filter, the described 3rd controllable opens
It is divided into two articles of branch roads after pass, second capacitor filter and the 4th gate-controlled switch, tie point is connected to electrical network,
Second branch road is connected to local load；The coil of the 5th gate-controlled switch is connected with second gate-controlled switch and is followed by described
Second capacitor filter two ends；After the normally-closed contact of the 5th gate-controlled switch is connected with the coil of the 6th gate-controlled switch
It is connected between the zero line of the tie point and live wire；The normally opened contact of the 6th gate-controlled switch is connected on the tie point
Live wire on；
Described control unit, for when photovoltaic energy storage invertor operation is in off-network pattern, keeping first gate-controlled switch, institute
State the second gate-controlled switch, the 3rd gate-controlled switch and the 4th gate-controlled switch closure；Judge whether electrical network recovers normal；If
It is normal that judgement obtains power system restoration, then control photovoltaic energy storage inverter and shut down, disconnect the 3rd gate-controlled switch, the described 4th can
Control switch and second gate-controlled switch, and when the first capacitor filter self discharge is completed, disconnect described first
Gate-controlled switch；Control photovoltaic energy storage inverter startup, and close the 3rd gate-controlled switch and the 4th gate-controlled switch.
10. off-grid grid-connected switching circuit according to claim 9, it is characterised in that the main circuit also includes：With it is described
The hand switch that the coil of the 6th gate-controlled switch is in series, the hand switch is defaulted as closure state；
It is corresponding, before described control unit control photovoltaic energy storage inverter is shut down, it is additionally operable to judge to obtain the hand switch
On off state is closure state.
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| CN201610963967.9A CN106655255B (en) | 2016-10-28 | 2016-10-28 | Photovoltaic energy storage inverter and/off-network, off-grid grid-connected switching method and circuit |
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| CN106655255B (en) | 2018-11-06 |
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