CN206658046U - A kind of switching overvoltage protection device of multilevel photovoltaic grid-connected inverter - Google Patents
A kind of switching overvoltage protection device of multilevel photovoltaic grid-connected inverter Download PDFInfo
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- CN206658046U CN206658046U CN201720269869.5U CN201720269869U CN206658046U CN 206658046 U CN206658046 U CN 206658046U CN 201720269869 U CN201720269869 U CN 201720269869U CN 206658046 U CN206658046 U CN 206658046U
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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
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- 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
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Abstract
A kind of switching overvoltage protection device of multilevel photovoltaic grid-connected inverter, the device include continuous input cell, multi-level inverse conversion unit, control unit, voltage detection unit and current detecting unit；The output end of continuous input cell is connected with the direct-flow input end of multi-level inverse conversion unit, the ac output end of multi-level inverse conversion unit is connected with power network by net side switch K but is not limited only to be connected with power network, the input of voltage detection unit is connected with grid side, the output end of voltage detection unit is connected with the input of control unit, the input of current detecting unit is connected with the ac output end of multi-level inverse conversion unit, the output end of current detecting unit is connected with another input of control unit, the output end of control unit is connected with the drive end of switching tube in multi-level inverse conversion unit；Inversion unit output voltage effectively can be reduced within threshold range by the utility model, the safety of the outlet side electronic load of protection exchange in time；And system loss is small.
Description
Technical field
Photovoltaic power supply technical field is the utility model is related to, the utility model is related to a kind of switching overvoltage protection device,
More particularly, to a kind of switching overvoltage protection device applied to multilevel photovoltaic grid-connected inverter.
Background technology
The ac output end of photovoltaic combining inverter is directly connected by points of common connection with power network, while can on port
Other load equipments can be connected, rear port voltage are connected with power network by power network clamper, port voltage amplitude is by line voltage size
Determine.When isolated island occurs for power network, net side switches off, and inverter disconnects with power network, and the voltage of net side points of common connection is no longer
By power network clamper, while inverter still may proceed to provide idle work(to power network before detecting that generation isolated island stopping is grid-connected
Rate, the voltage of inverter ac side points of common connection is caused to rise.In order to prevent the electronic load of inverter ac output end by
To the impact of high voltage, the transient voltage of inverter ac output end is not to be exceeded《NB/T 32004-2013 photovoltaic generations are simultaneously
Net inverter technology specification》In required limit value.
For three-phase grid-connected inverter, for problem above present in grid-connected, prior art is according to three-phase power grid voltage
Orthogonal dq rotating coordinate systems are established, by the inverter voltage d axis components or line voltage that calculate three-phase grid-connected inverter
Whether there occurs switching overvoltage to judge the ac output end of inverter for virtual value.It is past when judging to occur switching overvoltage
Voltage toward grid side has built up, even if now stopping is grid-connected, the safety electric capacity Cx of inverter ac output end (is usually X
Electric capacity) both ends voltage it is higher, now typically discharged by the internal resistance in inverter.Obvious safety electric capacity Cx
The smaller electric discharge of capacitance it is faster, but electromagnetic compatibility (EMC) characteristic of inverter can be influenceed；The resistance of inverter internal resistance is got over
Small electric discharge is faster, but extra loss can be brought to inverter, increases the cost of inverter.
The content of the invention
In order to solve the above technical problems, the utility model provides a kind of behaviour applied to multilevel photovoltaic grid-connected inverter
Make overvoltage protection and method, the device mainly detects line voltage by detection unit, by detecting line voltage
Whether isolated island occurs, switch to the work shape of switching overvoltage protection from grid-connected working condition by control unit control inverter
State, until the ac output voltage of inverter drops to given voltage, whole operation overvoltage protection process just terminates, inverter
In holding state, wait again grid-connected；The device and guard method use simple circuit structure, and combination controlling method,
When isolated island occurs for power network, inverter and power network are first disconnected into quick disconnection, are then reduced to inverter ac output voltage
Within the scope of standard is required, the electronic equipment that inverter ac side is connected is effectively protected.
In order to achieve the above object, the utility model adopts the following technical scheme that：
A kind of switching overvoltage protection device of multilevel photovoltaic grid-connected inverter, the device include continuous input cell,
Multi-level inverse conversion unit, control unit, voltage detection unit and current detecting unit；The output end of the continuous input cell with
The direct-flow input end of multi-level inverse conversion unit is connected, and the ac output end of the multi-level inverse conversion unit switchs K by net side
It is connected with power network but is not limited only to be connected with power network, the input of the voltage detection unit is connected with grid side, uses
In detection line voltage, the output end of the voltage detection unit is connected with the input of control unit, the current detecting
The input of unit is connected with the ac output end of multi-level inverse conversion unit, the output end of the current detecting unit and control
Another input of unit is connected, the output end of described control unit and the drive end phase of switching tube in multi-level inverse conversion unit
Connection, for controlling the working condition of multi-level inverse conversion unit switch pipe.
The multi-level inverse conversion unit is single-phase or three-phase；Multi-level inverse conversion unit by dc bus module, inverter bridge leg,
Ac filter module is sequentially connected in series composition, and the dc bus module is that n-1 bus capacitor is in series, and n is level
Number；The multi-level inverse conversion bridge arm includes " zero " level switch group, " just " level switch group and " negative " level switch group, described
" zero " level switch group is connected in series between bus capacitor midpoint and " just " level switch group and " negative " level switch group, described
Ac filter module is by filter inductance L and filter capacitor CinvComposition, one end of the filter inductance L and the output of inverter bridge leg
Be connected, the other end be multi-level inverse conversion unit positive output end, the filter capacitor CinvOne end and multi-level inverse conversion unit
Positive output end be connected, filter capacitor CinvThe other end be connected with bus capacitor midpoint as multi-level inverse conversion unit
Negative output terminal.
Compared to the prior art, the utility model possesses following advantage：
1. for the utility model device when inversion unit output voltage exceeds threshold value, system can be effectively defeated by inversion unit
Go out voltage to be reduced within threshold range, the safety of the outlet side electronic load of protection exchange in time.
2. the protection device and method are will to exchange to export the electric energy feedback exceeded to dc bus, rather than pass through system
Internal resistance is consumed, so system loss is small.
Brief description of the drawings
Fig. 1 switching overvoltage protection device block diagrams.
Fig. 2 multi-level inverse conversion element circuit block diagrams.
Fig. 3 switching overvoltage guard method control flow charts.
Fig. 4 is single-phase T-shaped three-level inverter.
Fig. 5 is that four operation modes after switching overvoltage occur for single-phase T-shaped three-level inverter, (a) in wherein Fig. 5
The circuit working state being transferred to for [0, D × Ts] period filter capacitor in filter inductance L, (b) in Fig. 5 for [D × Ts,
Ts] energy of period filter inductance is fed to the circuit working state of dc bus module, and (c) in Fig. 5 is [0, D × Ts]
Circuit working state in the energy transfer of period filter capacitor to filter inductance L.(d) in Fig. 5 is [D × Ts, the Ts] period
The energy of filter inductance is fed to the circuit working state of dc bus module.
Fig. 6 is the T-shaped three-level inverter of three-phase.
Fig. 7 is single-phase I types three-level inverter.
Fig. 8 is that four operation modes after switching overvoltage occur for single-phase I types three-level inverter, in wherein Fig. 8
(a) be transferred to circuit working state in filter inductance L for [0, D × Ts] period filter capacitor, (b) in Fig. 8 for [D ×
Ts, Ts] energy of period filter inductance is fed to the circuit working state of dc bus module, (c) in Fig. 8 for [0, D ×
Ts] period filter capacitor energy transfer to filter inductance L in circuit working state, (d) in Fig. 8 is [D × Ts, Ts]
The energy of period filter inductance is fed to the circuit working state of dc bus module.
Fig. 9 is three-phase I type three-level inverters.
Figure 10 is three-phase I type five-electrical level inverters.
Embodiment
Shown embodiment is further described to the utility model below in conjunction with the accompanying drawings.
Fig. 1 is switching overvoltage protection device block diagram, as illustrated, a kind of applied to multilevel photovoltaic grid-connected inverter
Switching overvoltage protection device and method, the device include continuous input cell, multi-level inverse conversion unit, control unit, voltage
Detection unit and current detecting unit.The output end of the continuous input cell and the direct-flow input end phase of multi-level inverse conversion unit
Connection, the ac output end of the multi-level inverse conversion unit switchs K by net side and is connected with power network, while the exchange of inversion unit
Output end can also be connected to other electronic loads, and the input of the voltage detection unit is connected with grid side, for detecting electricity
Net voltage, the output end of the voltage detection unit are connected with the input of control unit, the current detecting unit it is defeated
Enter end with the ac output end of multi-level inverse conversion unit to be connected, the output end of the current detecting unit and control unit it is another
One input is connected, and the output end of described control unit is connected with the drive end of switching tube in multi-level inverse conversion unit, uses
In the working condition of control multi-level inverse conversion unit switch pipe.
Fig. 2 is multi-level inverse conversion element circuit block diagram, as illustrated, the multi-level inverse conversion unit is single-phase or three-phase.
Multi-level inverse conversion unit is sequentially connected in series and formed by dc bus module, inverter bridge leg, ac filter module.The direct current is female
Wire module is that (n-1) individual bus capacitor is in series, and n is level number；The multi-level inverse conversion bridge arm includes " zero " level switch
Group, " just " level switch group and " negative " level switch group, " zero " the level switch group be connected in series in bus capacitor midpoint with
" just " between level switch group and " negative " level switch group, the ac filter module is by filter inductance L and filter capacitor C groups
Into one end of the filter inductance L is connected with the output of multi-level inverse conversion bridge arm, and other end is the positive output of inversion unit
End, the filter capacitor CinvOne end be connected with the output end of multi-level inverse conversion unit, filter capacitor CinvThe other end with
Bus capacitor midpoint, which is connected, is connected in the negative output terminal of multi-level inverse conversion unit.
Fig. 3 is switching overvoltage guard method control flow chart, the control method of the switching overvoltage protection device：
Step 1：Voltage detection unit detects line voltage V in real time, and gives the voltage detected to control unit and carry out
Data processing；
Step 2：Control unit is handled the voltage data sent, when detecting line voltage virtual value VaveIt is less than
The given threshold value V of systemGWhen, control unit control multi-level inverse conversion unit keeps grid-connected working condition；When detecting electricity
Net voltage effective value is more than the threshold value V that system givesGWhen, control unit sends control signal, owns multi-level inverse conversion unit
Switching tube disconnects, while multi-level inverse conversion unit is immediately switched to switching overvoltage guard mode from simultaneously net state, waits to be controlled
Unit re-emits control signal；
Step 3：Switching overvoltage guard mode is carried out, i.e. control unit sends control letter to zero level switches set again
Number, make zero level switches set ON operation, multi-level inverse conversion unit is internally formed current loop, exchanges multi-level inverse conversion unit
Output end voltage is fed back in the dc bus module of inversion unit direct-flow input end.
Step 4：When multi-level inverse conversion unit ac output end magnitude of voltage V is more than safe voltage value Vsafe(the safety electricity
Pressure value VsafeIt is the inverter safety value required when carrying out switching overvoltage), then continue executing with step 3 and operated electricity
Pressure protection；When multi-level inverse conversion unit ac output end voltage V is less than safe voltage value Vsafe, control unit, which will be sent, controls letter
Number, turn off zero level switches set, switching overvoltage guard mode stops, and net side switch K is disconnected, and multi-level inverse conversion unit is in
Holding state, switching overvoltage protection process terminate.
Fig. 4 is single-phase T-shaped three-level inverter, as illustrated, dc-link capacitance is by the first electric capacity C1 and the second electric capacity
C2 is connected in series, and zero level switch is connected between the first electric capacity C1 and the second electric capacity C2 midpoint and the midpoint of inverter bridge leg,
Zero level switch is connected in series by the first zero level switching tube S2 and the second zero level switching tube S3, the first zero level switch
Pipe S2 colelctor electrode is connected with the first electric capacity C1 and the second electric capacity C2 midpoint, the current collection of the second zero level switching tube S3
Pole is connected with the midpoint of inverter bridge leg, the emitter-base bandgap grading of the first zero level switching tube S2 and the second zero level switching tube S3 emitter-base bandgap gradings
It is connected.Positive level switch S1 colelctor electrode is connected with the first electric capacity C1 positive pole, positive level switch S1 emitter-base bandgap grading and
Negative level switch S4 colelctor electrode is connected, and negative level switch S4 emitter-base bandgap grading is connected with the second electric capacity C2 negative pole.Inductance L's
One end is connected with the midpoint of inverter bridge leg, the other end and the filter capacitor C of the inductance LinvOne end be connected, the filter
Ripple electric capacity CinvThe other end be connected with the first electric capacity C1 and the second electric capacity C2 midpoint.
Fig. 5 is that four operation modes after switching overvoltage occur for single-phase T-shaped three-level inverter, as illustrated, " zero "
Level switch pipe includes the first zero level switching tube S2 and the second zero level switching tube S3.When digital controller senses to there occurs
After switching overvoltage, digitial controller sends dutycycle D (0 to " zero " level switch pipe<D<1) drive signal, switch periods
For Ts, while forbid the work of rest switch pipe.Now when " zero " level switch pipe is opened or turned off, inverter shares four
Individual operation mode：
Mode 1：Shown in (a) in equivalent circuit such as Fig. 5, now filter capacitor CinvBoth end voltage is more than zero, in switch week
[0, the D × Ts] period of phase, the first zero level switching tube S2 in " zero " level switch turn on the second zero level switching tube S3,
Other power switch pipes turn off.Filter capacitor CinvEnergy transfer into filter inductance L；
Mode 2：Shown in (b) in equivalent circuit such as Fig. 5, now filter capacitor CinvBoth end voltage is more than zero, in switch week
[D × Ts, the Ts] period of phase, all switching tube shut-offs.Filter inductance L electric currents pass through positive level switching tube S1Body diode continue
Stream, the energy of filter inductance are fed to dc bus module；
Mode 3：Shown in (c) in equivalent circuit such as Fig. 5, now filter capacitor CinvBoth end voltage is less than zero, in switch week
[0, the D × Ts] period of phase, the first zero level switching tube S2 in " zero " level switch turn on the second zero level switching tube S3,
Other power switch pipes turn off.Filter capacitor CinvEnergy transfer into filter inductance L；
Mode 4：Shown in (d) in equivalent circuit such as Fig. 5, now filter capacitor CinvBoth end voltage is less than zero, in switch week
[D × Ts, the Ts] period of phase, all switching tube shut-offs.Filter inductance electric current passes through negative level switching tube S4Body diode continue
Stream, filter inductance L energy are fed to dc bus module；
The please modification according to me to Fig. 5 descriptions, change the title of part in following yellow font, pays attention to identical letter with
Same title is equally used to Fig. 5 descriptions！
Fig. 6 is the T-shaped three-level inverter of three-phase.As illustrated, dc-link capacitance is by the first electric capacity C1 and the second electric capacity
C2 is connected in series, and the zero level switches set of a phases is connected in the first electric capacity C1 and the second electric capacity C2 midpoint and inverter bridge leg
Between point, zero level switch is connected in series by the first zero level switching tube S2a and the second zero level switching tube S3a respectively, described
First zero level switching tube S2a colelctor electrode is connected with the first electric capacity C1 and the second electric capacity C2 midpoint, the 2nd 0 electricity
Flat switching tube S3a colelctor electrode is connected with the midpoint of inverter bridge leg, the emitter-base bandgap grading and second of the first zero level switching tube S2a
Zero level switching tube S3a emitter-base bandgap gradings are connected.The colelctor electrode of the positive level switch S1a is connected with the first electric capacity C1 positive pole,
Positive level switch S1a emitter-base bandgap grading and negative level switch S4a colelctor electrode is connected, and the negative level switchs S4a emitter-base bandgap grading and the
Two electric capacity C2a negative pole is connected.The output termination ac filter module of a phases.The circuit of the b phases and c phases and a phase phases
Together, here is omitted.The switching overvoltage protection operation mode of the circuit is identical with single-phase T-shaped three-level inverter simultaneously.
Fig. 7 is single-phase I types three-level inverter.As illustrated, single-phase I types tri-level circuit is to carry inverse parallel by four
The switching tube of diode is connected in series, and positive level switching tube S1Drain electrode be connected with the first electric capacity C1 positive pole, positive level
Switching tube S1Source electrode and the first zero level switching tube S2Drain series connection, the first zero level switching tube S2Source electrode and
Two zero level switching tube S3Drain series connection, the second zero level switching tube S3Source electrode and negative level switching tube S4Drain electrode
It is connected in series, negative level switching tube S4Source electrode be connected with the second electric capacity C2 negative pole.The power supply positive and negative and between go here and there
It is associated with the first electric capacity C1 and the second electric capacity C2, the positive level switching tube S1With the first zero level switching tube S2Series connection point and first
The first diode of zero level D is connected between electric capacity C1 and the second electric capacity C2 series connection point N1, the first diode of zero level D1's
Anode is connected with N points, the first diode of zero level D1Negative electrode and positive level switching tube S1With zero level first switch pipe S2's
Series connection point is connected.The zero level second switch pipe S3With negative level switching tube S4Series connection point and the first electric capacity C1 and the second electricity
The second diode of zero level D is connected between appearance C2 series connection point N2, the second diode of zero level D2Negative electrode be connected with N points,
The second diode of zero level D2Anode and zero level second switch pipe S3With negative level switching tube S4Series connection point be connected, institute
State zero level first switch pipe S2With zero level second switch pipe S3Series connection point connect filter inductance a L, the filter inductance L
The other end and the first electric capacity C1 and the second electric capacity C2 midpoint N between connect a filter capacitor Cinv, filter capacitor CinvBoth ends are simultaneously
It is associated with a load resistance R.
Fig. 8 is that four operation modes after switching overvoltage occur for single-phase I types three-level inverter, as illustrated, " zero "
Level switch pipe includes power switch pipe zero level first switch S2With zero level second switch S3.When digital controller senses arrive
After switching overvoltage, digitial controller sends dutycycle D (0 to " zero " level switch pipe<D<1) drive signal, is opened
The pass cycle is Ts, while forbids the work of rest switch pipe.Now when " zero " level switch pipe is opened or turned off, inverter
Share four operation modes：
Mode 1：Shown in (a) in equivalent circuit such as Fig. 8, now filter capacitor CinvBoth end voltage is more than zero, in switch week
[0, the D × Ts] period of phase, the first zero level switching tube S2 and the second zero level switching tube S in " zero " level switch3Conducting,
Other power switch pipes turn off.Filter capacitor CinvEnergy transfer into filter inductance L；
Mode 2：Shown in (b) in equivalent circuit such as Fig. 8, now filter capacitor CinvBoth end voltage is more than zero, in switch week
[D × Ts, the Ts] period of phase, all switching tube shut-offs.Filter inductance L electric currents close pipe S by opening positive level1Body diode and
Zero level switching tube S2Body diode afterflow, filter inductance L energy is fed to dc bus module；
Mode 3：Shown in (c) in equivalent circuit such as Fig. 8, now filter capacitor CinvBoth end voltage is less than zero, in switch week
[0, the D × Ts] period of phase, the first zero level switching tube S in " zero " level switch2Turned on the second zero level switching tube S3,
Other power switch pipes turn off.Filter capacitor Cin energy transfer is into filter inductance L；
Mode 4：Shown in (d) in equivalent circuit such as Fig. 8, now filter capacitor CinvBoth end voltage is less than zero, in switch week
[D × Ts, the Ts] period of phase, all switching tube shut-offs.Filter capacitor CinvBoth end voltage is less than zero, and inversion inductor electric current passes through
Second zero level switching tube S3Body diode and negative level switching tube S4Body diode afterflow, filter inductance L energy feeding
To dc bus；
Fig. 9 is three-phase I type three-level inverters.As illustrated, the circuit is combined by three single-phase I types tri-level circuits
's.Operation mode is close with the single-phase I types three-level inverter of embodiment, and here is omitted.
Figure 10 is three-phase I type five-electrical level inverters, as illustrated, the circuit is by three single-phase level circuit groups of I types five
Close, operation mode is close with the single-phase I types three-level inverter of embodiment, and here is omitted.
By the various embodiments described above as can be seen that the multi-level inverter circuit that this programme is applicable can have a variety of modifications, when
During generation switching overvoltage, as long as control " zero " level switch pipe turns on and off, remaining power switch pipe is held off, just
The guard time requirement of switching overvoltage can be met.This programme is not on the premise of extra hardware expense is increased, by simple
Control method disclosure satisfy that switching overvoltage protection needs.
Above-described embodiment only illustrates technical concepts and features of the present utility model, and its object is to allow be familiar with technique
Personage can understand content of the present utility model and implement according to this, can not limit the scope of protection of the utility model with this.It is all
The equivalent change or modification made according to the utility model Spirit Essence, should all cover the scope of protection of the utility model it
It is interior.
Claims (2)
- A kind of 1. switching overvoltage protection device of multilevel photovoltaic grid-connected inverter, it is characterised in that：Inputted including direct current single Member, multi-level inverse conversion unit, control unit, voltage detection unit and current detecting unit；The output of the continuous input cell End is connected with the direct-flow input end of multi-level inverse conversion unit, and the ac output end of the multi-level inverse conversion unit is opened by net side K is closed with power network to be connected but be not limited only to be connected with power network, the input of the voltage detection unit is connected with grid side, For detecting line voltage, the output end of the voltage detection unit is connected with the input of control unit, the electric current inspection The input for surveying unit is connected with the ac output end of multi-level inverse conversion unit, the output end of the current detecting unit and control Another input of unit processed is connected, the output end and the drive end of switching tube in multi-level inverse conversion unit of described control unit It is connected, for controlling the working condition of multi-level inverse conversion unit switch pipe.
- 2. a kind of switching overvoltage protection device of multilevel photovoltaic grid-connected inverter according to claim 1, its feature It is：The multi-level inverse conversion unit is single-phase or three-phase；Multi-level inverse conversion unit is by dc bus module, inverter bridge leg, friendship Stream filtration module is sequentially connected in series composition, and the dc bus module is that n-1 bus capacitor is in series, and n is level number； The multi-level inverse conversion bridge arm includes " zero " level switch group, " just " level switch group and " negative " level switch group, " zero " Level switch group is connected in series between bus capacitor midpoint and " just " level switch group and " negative " level switch group, the exchange Filtration module is by filter inductance L and filter capacitor CinvComposition, one end of the filter inductance L is connected with the output of inverter bridge leg Connect, the other end be multi-level inverse conversion unit positive output end, the filter capacitor CinvOne end and multi-level inverse conversion unit just Output end is connected, filter capacitor CinvThe other end be connected with bus capacitor midpoint as the negative defeated of multi-level inverse conversion unit Go out end.
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| CN201720269869.5U CN206658046U (en) | 2017-03-20 | 2017-03-20 | A kind of switching overvoltage protection device of multilevel photovoltaic grid-connected inverter |
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| CN201720269869.5U CN206658046U (en) | 2017-03-20 | 2017-03-20 | A kind of switching overvoltage protection device of multilevel photovoltaic grid-connected inverter |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106921146A (en) * | 2017-03-20 | 2017-07-04 | 特变电工西安电气科技有限公司 | The switching overvoltage protection device and method of a kind of multilevel photovoltaic grid-connected inverter |
| CN109038667A (en) * | 2018-08-18 | 2018-12-18 | 国网江苏省电力有限公司宿迁供电分公司 | One kind preventing family photovoltaic overvoltage controller and its control method |
-
2017
- 2017-03-20 CN CN201720269869.5U patent/CN206658046U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106921146A (en) * | 2017-03-20 | 2017-07-04 | 特变电工西安电气科技有限公司 | The switching overvoltage protection device and method of a kind of multilevel photovoltaic grid-connected inverter |
| CN109038667A (en) * | 2018-08-18 | 2018-12-18 | 国网江苏省电力有限公司宿迁供电分公司 | One kind preventing family photovoltaic overvoltage controller and its control method |
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| GR01 | Patent grant | ||
| GR01 | Patent grant |