CN104779825B - Cross type sub-module structure of modular multilevel converter (MMC) - Google Patents
Cross type sub-module structure of modular multilevel converter (MMC) Download PDFInfo
- Publication number
- CN104779825B CN104779825B CN201510124229.0A CN201510124229A CN104779825B CN 104779825 B CN104779825 B CN 104779825B CN 201510124229 A CN201510124229 A CN 201510124229A CN 104779825 B CN104779825 B CN 104779825B
- Authority
- CN
- China
- Prior art keywords
- switching tube
- positive terminal
- pipe
- negative pole
- pole end
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000003990 capacitor Substances 0.000 claims abstract description 3
- 230000005611 electricity Effects 0.000 claims description 4
- RZBCCAZHJQZKLL-UHFFFAOYSA-N 5-methoxy-12-methyl-11h-indolo[2,3-a]carbazole-6-carbonitrile Chemical compound N1C2=C3N(C)C4=CC=C[CH]C4=C3C(OC)=C(C#N)C2=C2[C]1C=CC=C2 RZBCCAZHJQZKLL-UHFFFAOYSA-N 0.000 abstract description 8
- 238000010586 diagram Methods 0.000 description 6
- GIQCAMWUCKLMPC-UHFFFAOYSA-N 1-(4-hydroxy-3-methoxyphenyl)-2-(methylamino)propan-1-one Chemical compound CNC(C)C(=O)C1=CC=C(O)C(OC)=C1 GIQCAMWUCKLMPC-UHFFFAOYSA-N 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 3
- 238000010276 construction Methods 0.000 description 3
- 230000000903 blocking effect Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005538 encapsulation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000004224 protection Effects 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
- H02M7/483—Converters with outputs that each can have more than two voltages levels
-
- 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
- H02M7/483—Converters with outputs that each can have more than two voltages levels
- H02M7/4835—Converters with outputs that each can have more than two voltages levels comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Rectifiers (AREA)
Abstract
The invention discloses a cross type sub-module structure of a modular multilevel converter (MMC). The cross type sub-module structure comprises four switching tubes, four capacitors, a switching tube and an independent diode, wherein the sub-module structure is capable of outputting four levels to a greatest extent. In the practical application of the modular multi-level current converter, the number of the used sub-modules can be effectively reduced, the scale of a control circuit is reduced and the control complexity is reduced; the MCC formed by the sub-module has the capability of automatically clearing direct-current faults, quickly and effectively processing the direct-current faults and reducing the influence of the faults on the MMC and the overall alternating-current and direct-current system; compared with the CMMC, the MCC has the advantages that the number of IGBT devices is reduced by 10%; the operation loss is also reduced to a certain extent; the economy of the MCC is obviously superior to that of the CMMC.
Description
Technical field
The invention belongs to power electronic system technical field, and in particular to a kind of chiasma type of modularization multi-level converter
Sub-modular structure.
Background technology
Modularization multi-level converter (modular multilevel converter, MMC) has ac output voltage
Percent harmonic distortion is low, and modular construction is easy to encapsulation, and the electric stress that switching device bears is little, the low advantage of switching loss.From
After 2002 propose, through the development in more than ten years, extensively recognize for industry.Half-bridge submodule (half-bridge sub-
Module, HBSM) structure is the main submodule alternative constructions of MMC, because the loss of HBSM is little, voltage is low, almost institute at present
Some MMC high voltage DC engineerings are all for its topological structure with semi-bridge type MMC (MMC using HBSM, HMMC).But, when
When the high-voltage direct current that HMMC is constituted occurs DC bipolar short trouble, system cannot be cut off by locking inverter itself
Short-circuit current, this also serious harm safety of system.
At present, engineer applied of the dc circuit breaker in high-power occasion cannot also realize, and be made up of HMMC
DC transmission system again cannot be come disengagement failure short circuit current therefore whole by locking current conversion station when there is bipolar short trouble
Individual system can only failure occur after by AC circuit breaker come disengagement failure electric current, this brings sternly to the safe operation of system
Ghost image rings.In order to be avoided as much as DC Line Fault, existing MMC engineerings are as transmission line using the low cable of fault rate
Road rather than using lower-cost aerial line, this development to MMC DC transmission systems in terms of long distance powedr transmission is generated
Greatly restriction.
For effectively solving above-mentioned technical problem, at present many documents propose various with DC Line Fault self-cleaning ability
Submodule topology, such as clamper Shuangzi module (clamp double sub-module, CDSM) and full-bridge submodule (full-
Bridge sub-module, FBSM) etc..From the point of view of equipment cost and running wastage, CDSM is compared to other submodule topologys
Occupy more obvious advantage, but the MMC (MMC using CDSMs, CMMC) being made up of it compared to HMMC, CMMC needs many
With 25% IGBT device, the running wastage of extra consumption 40% or so.If submodule more more economical than CDSM can be worked out
Topology, necessarily with highly important construction value and application prospect.
The content of the invention
For the above-mentioned technical problem existing for prior art, the invention provides a kind of modularization multi-level converter
Chiasma type sub-modular structure, the MMC being made up of it not only has DC Line Fault self-cleaning ability, and compared to CMMC, is made
IGBT device number is less, and running wastage is lower, with more preferable economy.
A kind of chiasma type sub-modular structure of modularization multi-level converter, including：Four switching tube S1～S4, four electricity
Container C1～C4, one switches pipe and a separate diode；Wherein：
Electric capacity C1Positive terminal and switching tube S2Negative pole end be connected and constitute the high-pressure side of sub-modular structure, electric capacity C1's
Negative pole end and switching tube S1Positive terminal be connected, switching tube S1Negative pole end and electric capacity C2Positive terminal and separate diode
Negative electrode is connected, electric capacity C2Negative pole end and switching tube S2Positive terminal and switching pipe positive terminal be connected；The negative pole end of switching pipe
With electric capacity C3Positive terminal and switching tube S3Negative pole end be connected, the anode of separate diode and electric capacity C3Negative pole end and
Switching tube S4Positive terminal be connected, switching tube S4Negative pole end and electric capacity C4Positive terminal be connected, electric capacity C4Negative pole end with switch
Pipe S3Positive terminal be connected and constitute the low-pressure end of sub-modular structure；
Four switching tube S1～S4In either switch pipe include that two bands are anti-and IGBT pipe T of diode1～T2；
Wherein, IGBT pipes T1Emitter stage constitute switching tube positive terminal, IGBT pipe T1Colelctor electrode and IGBT pipe T2Emitter stage phase
Even, IGBT pipe T2Colelctor electrode constitute switching tube negative pole end, two IGBT pipe T1～T2Base stage receive from external equipment
The switch controlling signal of offer.
The IGBT pipes of the anti-simultaneously diode of described switching Guan Youyi bands are composed in parallel with a spark gap；Wherein, IGBT pipes
Emitter stage constitutes the positive terminal of switching pipe, and colelctor electrode constitutes the negative pole end of switching pipe, and base stage receives what is provided from external equipment
Switch controlling signal.
Described spark gap can effectively prevent the overvoltage of IGBT so as to exempt from overvoltage damage.
Sub-modular structure maximum of the present invention can export 4 level, in actual modularization multi-level converter application,
The number that submodule is used can be effectively reduced, the scale of control circuit and the complexity of control is reduced.
Compared with prior art, sub-modular structure of the present invention has the beneficial effect that：
(1) MMC being made up of submodule of the present invention has DC Line Fault self-cleaning ability, can fast and effeciently process straight
Stream failure, reduces impact of the failure to MMC and whole ac and dc systemses.
(2) MMC being made up of submodule of the present invention reduces 10% IGBT device number, running wastage compared to CMMC
Also having reduces to a certain extent, reflects that economy is better than CMMC.
(3) submodule maximum of the invention can export four level, export 1 level with HBSM and CDSM exports 2
Level is compared, and in the MMC of identical electric pressure, the submodule of the present invention is minimum using number, can effectively reduce controlling hardware and
The complexity of control algolithm.
Description of the drawings
Fig. 1 is chiasma type sub-modular structure schematic diagram of the present invention.
Fig. 2 (a) is that the level of chiasma type submodule 4 of the present invention puts into view.
Fig. 2 (b) is that the level of chiasma type submodule 2 of the present invention puts into view.
Fig. 2 (c) is chiasma type submodule of the present invention another kind 2 level input view.
Fig. 2 (d) is chiasma type submodule bypass condition schematic diagram of the present invention.
Fig. 3 (a) is the schematic diagram that current direction is A to B under chiasma type submodule blocking of the present invention.
Fig. 3 (b) is the schematic diagram that current direction is B to A under chiasma type submodule blocking of the present invention.
Fig. 4 is the schematic diagram of two CDSM cascades.
Specific embodiment
In order to more specifically describe the present invention, below in conjunction with the accompanying drawings and specific embodiment is to technical scheme
And its relative theory is described in detail.
As shown in figure 1, the chiasma type sub-modular structure of modularization multi-level converter of the present invention, including 4 switching tube S1
～S4, 4 capacitor C1～C4, 1 switches pipe and 1 separate diode D10。
Electric capacity C1Positive terminal and switching tube S2No. 2 ends be connected and constitute the A ends of chiasma type sub-modular structure, electric capacity C1
Negative pole end and switching tube S1No. 1 end be connected, switching tube S1No. 2 end with electric capacity C2Positive terminal and diode D10The moon
Extremely it is connected, electric capacity C2Negative pole end and switching tube S2No. 1 end and switch No. 1 of pipe end and be connected.No. 2 ends and the electricity of switching pipe
Hold C3Positive terminal and switching tube S3No. 2 end be connected, diode D10Anode and electric capacity C3Negative pole end and switching tube S4
No. 1 end be connected.Switching tube S4No. 2 end with electric capacity C4Positive terminal be connected, electric capacity C4Negative pole end and switching tube S3No. 1
Hold the B ends for being connected and constituting chiasma type sub-modular structure.
Switching tube S1～S4With identical internal structure, comprising two IGBT pipe T1And T2And it is anti-with what it was in parallel
To diode D1And D2.Wherein, IGBT pipes T1Emitter stage hold as No. 1 of switching tube, IGBT pipe T1Colelctor electrode and IGBT manage
T2Emitter stage be connected, IGBT pipe T2Colelctor electrode hold as No. 2 of switching tube.
Switching pipe is by 1 IGBT pipe T9, 1 diode D9With 1 spark gap, three is in parallel to be constituted, wherein, diode D9
With IGBT pipe T9Into reverse parallel connection relation.The addition of spark gap can effectively prevent IGBT pipe T9Overvoltage so as to exempted from electricity
Crushing is bad.
Fig. 2 gives four kinds of running statuses in the case of chiasma type sub-modular structure steady-state operation.Fig. 2 (a) show T1T2、
T7T8、T9It is open-minded, T3T4、T5T6In the case of shut-off, submodule exports the state of four level；Fig. 2 (b) show T1T2、T5T6、T9Open
It is logical, T3T4、T7T8In the case of shut-off, submodule exports the state of two level；Fig. 2 (c) show T3T4、T7T8、T9It is open-minded, T1T2、
T5T6In the case of shut-off, submodule exports the state of two level；Fig. 2 (d) show T3T4、T5T6、T9It is open-minded, T1T2、T7T8Shut-off
In the case of, the state of submodule bypass.During steady-state operation, T9All the time it is in the conduction state, there is no overvoltage problem.Actual work
In Cheng Yingyong, often a bridge arm of MMC is constituted by the cascade of hundreds of submodules, this causes the requirement for controlling hardware to increase,
Control algolithm is also complicated.So, in use, the chiasma type submodule of the present invention does not adopt two level states, but adopt
The investing method of four level, greatly reduces the number that submodule is used, and reduces the scale of control circuit and the complexity of control.
Fig. 3 gives two kind running statuses of the chiasma type sub-modular structure under latch status under different current directions.Fig. 3
A () is situation of the sense of current from A to B, Fig. 3 (b) is situation of the sense of current from B to A.In the case of current direction A to B,
The sense of current will bear the back-emf of four level；In the case of current direction B to A, the sense of current will bear two level
Back-emf.Therefore, either which kind of sense of current circulation, electric current charges all the time to electric capacity, increases capacitance voltage, such that it is able to
Set up larger inverse electromotive force to cut off direct fault current.From Fig. 3 (b) as can be seen that in D10When conducting, C2And C3On
Voltage will be superimposed upon T9On so that T9The rated voltage of more twice is temporarily born, accordingly, it would be desirable to lightning arrester connected in parallel thereon
To protect T9.In fact, in engineer applied, the rated voltage under IGBT steady-state operations is generally the half left side that it can bear voltage
The right side, therefore, T9Itself has the ability for bearing double voltage, so an IGBT device just can be competent at.
Under normal operation, a chiasma type submodule can export four level, and CDSM can only to export two electric
It is flat.Thus, in actual applications, a chiasma type submodule regards into the CDSM of two cascades as one equivalent to two CDSM
Individual new submodule, just can compare to very simple the economy between chiasma type submodule and CDSM.Fig. 4 gives two
The schematic diagram of CDSM cascades, it can be seen that the CDSM of two cascades includes 10 IGBT pipes, and chiasma type submodule is only
Need 9 IGBT pipe, therefore, the MMC being made up of each of which in the use number of IGBT pipes, chiasma type submodule compared to
CDSM saves 10%.
Table 1 gives above-mentioned two classes submodule under steady-state operation, the conducting state of power electronic devices.Can be with from table
Find out, when the sense of current is A to B, no matter which kind of state submodule is in, and the structure of two CDSM cascades is all than chiasma type submodule
1 diode is put into block more；When the sense of current is B to A, no matter submodule is in which kind of state, the structure of two CDSM cascades
1 IGBT pipe is put into all than chiasma type submodule more.Therefore, it can draw, under identical voltage and capacity situation, CMMC ratios are by handing over
The MMC that forked type submodule is constituted consumes more on-state loss.
Table 1
Table 2 gives above-mentioned two classes submodule under steady-state operation, the on off operating mode of power electronic devices.Can be with from table
Find out, between switching, the situation of chiasma type submodule and two CDSM cascades is identical, show that there is identical switch to damage for both
Consumption.
Table 2
Can draw from Tables 1 and 2, compared to CDSM, chiasma type submodule of the present invention has less running wastage, plus
It is few use 10% IGBT to manage, chiasma type submodule has more economy.
The above-mentioned description to embodiment is understood that for ease of those skilled in the art and using this
It is bright.Person skilled in the art obviously easily can make various modifications to above-described embodiment, and described herein
General Principle is applied in other embodiment without through performing creative labour.Therefore, the invention is not restricted to above-described embodiment,
Those skilled in the art's announcement of the invention, the improvement made for the present invention and modification all should be in the protections of the present invention
Within the scope of.
Claims (1)
1. the chiasma type sub-modular structure of a kind of modularization multi-level converter, it is characterised in that include：Four switching tube S1~
S4, four capacitor C1～C4, one switches pipe and a separate diode；Wherein：
Electric capacity C1Positive terminal and switching tube S2Negative pole end be connected and constitute the high-pressure side of sub-modular structure, electric capacity C1Negative pole
End and switching tube S1Positive terminal be connected, switching tube S1Negative pole end and electric capacity C2Positive terminal and separate diode negative electrode
It is connected, electric capacity C2Negative pole end and switching tube S2Positive terminal and switching pipe positive terminal be connected；The negative pole end of switching pipe and electricity
Hold C3Positive terminal and switching tube S3Negative pole end be connected, the anode of separate diode and electric capacity C3Negative pole end and switch
Pipe S4Positive terminal be connected, switching tube S4Negative pole end and electric capacity C4Positive terminal be connected, electric capacity C4Negative pole end and switching tube S3
Positive terminal be connected and constitute the low-pressure end of sub-modular structure；
Four switching tube S1～S4In either switch pipe include that two bands are anti-and IGBT pipe T of diode1～T2；Wherein,
IGBT pipe T1Emitter stage constitute switching tube positive terminal, IGBT pipe T1Colelctor electrode and IGBT pipe T2Emitter stage be connected, IGBT
Pipe T2Colelctor electrode constitute switching tube negative pole end, two IGBT pipe T1～T2Base stage receive from external equipment provide
Switch controlling signal；
The IGBT pipes of the anti-simultaneously diode of described switching Guan Youyi bands are composed in parallel with a spark gap；Wherein, the transmitting of IGBT pipes
Pole constitutes the positive terminal of switching pipe, and colelctor electrode constitutes the negative pole end of switching pipe, and base stage receives the switch provided from external equipment
Control signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510124229.0A CN104779825B (en) | 2015-03-20 | 2015-03-20 | Cross type sub-module structure of modular multilevel converter (MMC) |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510124229.0A CN104779825B (en) | 2015-03-20 | 2015-03-20 | Cross type sub-module structure of modular multilevel converter (MMC) |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN104779825A CN104779825A (en) | 2015-07-15 |
| CN104779825B true CN104779825B (en) | 2017-04-12 |
Family
ID=53621112
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201510124229.0A Active CN104779825B (en) | 2015-03-20 | 2015-03-20 | Cross type sub-module structure of modular multilevel converter (MMC) |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104779825B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105429495B (en) * | 2015-12-10 | 2017-11-14 | 西南交通大学 | A kind of Modular multilevel converter using polymorphic submodule |
| CN105978375B (en) * | 2016-06-21 | 2018-07-24 | 浙江大学 | Chiasma type submodule and its MMC control methods suitable for the transmission of electricity of remote large capacity overhead line |
| CN107370393A (en) * | 2017-06-29 | 2017-11-21 | 全球能源互联网研究院 | A kind of Modularized multi-level converter sub-module topological structure and its guard method |
| CN108418454B (en) * | 2018-03-05 | 2019-12-24 | 武汉大学 | Modular multilevel converter and multiple cross sub-module thereof |
| CN111200366A (en) * | 2020-01-15 | 2020-05-26 | 西安交通大学 | MMC submodule topological structure of equivalent full-bridge submodule with direct-current fault blocking capability |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102611096A (en) * | 2012-03-13 | 2012-07-25 | 浙江大学 | Bipolar direct current power transmission system with direct current failure self-elimination capacity |
| CN103248255B (en) * | 2013-05-24 | 2014-12-31 | 哈尔滨工业大学 | Tri-phase modular multi-level converter and fault-tolerate detecting method for IGBT (insulated gate bipolar translator) open circuit fault in sub-modules thereof |
| CN104052026B (en) * | 2014-05-29 | 2016-05-25 | 华中科技大学 | For submodule topology and the application thereof of modularization multi-level converter |
| CN104167912B (en) * | 2014-08-14 | 2016-08-31 | 华中科技大学 | A kind of MMC possessing zero DC voltage fault ride-through capacity and method for designing thereof |
-
2015
- 2015-03-20 CN CN201510124229.0A patent/CN104779825B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN104779825A (en) | 2015-07-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104779825B (en) | Cross type sub-module structure of modular multilevel converter (MMC) | |
| CN106786403B (en) | Direct current solid-state circuit breaker with follow current loop | |
| WO2017024598A1 (en) | Mmc-hvdc system, and direct-current side isolation device and isolation method therefor | |
| US11394197B2 (en) | Ring-connected bridge-type multi-port hybrid DC circuit breaker | |
| WO2021218227A1 (en) | Modular capacitor commutated converter and method | |
| KR20180103181A (en) | DC current interrupter and control method | |
| EP2940852B1 (en) | Converter | |
| CN110829393A (en) | Current-limiting hybrid direct-current circuit breaker with active protection function and control method | |
| KR101689824B1 (en) | Modular Multilevel Converter and Submodule of the Converter | |
| CN103731059A (en) | Novel double-clamping sub-module structure circuit of modular multilevel converter | |
| CN110460024A (en) | A kind of DC grid trend controllable type multiport dc circuit breaker and its control method | |
| CN104601017A (en) | Modularized multi-level converter being able to traverse direct current short circuit fault | |
| CN110768233A (en) | Combined high-voltage direct-current circuit breaker applicable to direct-current power grid and having power flow control function and control method thereof | |
| WO2021243501A1 (en) | Fault protection apparatus | |
| CN105071675A (en) | Hybrid power switch and application thereof in flexible direct current power transmission converter | |
| CN111030060A (en) | Clamp-on circuit breaker topology suitable for direct current fault removal | |
| CN111030493A (en) | Submodule of modular multilevel converter and protection circuit thereof | |
| CN108616223B (en) | IGCT-based modularized multi-level converter and fault processing method | |
| CN210201475U (en) | Controllable type multiport direct current circuit breaker of direct current electric wire netting trend | |
| CN105450045B (en) | A kind of modular multi-level converter based on diagonal bridge submodule | |
| CN209170243U (en) | A kind of modularization multi-level converter | |
| US20230170792A1 (en) | Power conversion circuit, power transmission system, and photovoltaic device | |
| CN108599228B (en) | Flexible direct current transmission converter and bipolar flexible direct current transmission system | |
| CN110034545A (en) | Bridge type multiport solid-state direct current circuit breaker | |
| CN114844368A (en) | Direct-current transformer and low-voltage bidirectional fault current suppression method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| EXSB | Decision made by sipo to initiate substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |