CN110601570A - Many level of modularization current regulator - Google Patents
Many level of modularization current regulator Download PDFInfo
- Publication number
- CN110601570A CN110601570A CN201910829985.1A CN201910829985A CN110601570A CN 110601570 A CN110601570 A CN 110601570A CN 201910829985 A CN201910829985 A CN 201910829985A CN 110601570 A CN110601570 A CN 110601570A
- Authority
- CN
- China
- Prior art keywords
- diode
- bridge arm
- switch
- anode
- bridge
- 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.)
- Pending
Links
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
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M7/219—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only in a bridge configuration
-
- 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
- Y02E10/70—Wind energy
- Y02E10/76—Power conversion electric or electronic aspects
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Rectifiers (AREA)
Abstract
The invention relates to a modular multi-level rectifier, and belongs to the technical field of power electronic power conversion. Each phase of the rectifier comprises an upper bridge arm and a lower bridge arm, each bridge arm is formed by cascading N identical submodules, and the submodules adopt clamping type rectifier submodules. The sub-modules of the invention have four voltage output states of positive, one-half positive, 0 and one-half negative, so the output voltage of the direct current side can be continuously adjusted between a positive rated value and 0, meanwhile, the sub-modules are equivalent to only 3 switching tubes in two half-bridge sub-modules relative to a half-bridge type converter, only 3 small-capacity diodes only used in an uncontrolled charging stage are added to each two half-bridge sub-modules, and the capability of adjusting the transmission power through the direct current voltage at the rectification side in the offshore wind power series connection system can be realized at lower cost than the half-bridge type converter.
Description
Technical Field
The invention relates to a modular multi-level rectifier, and belongs to the technical field of power electronic power conversion.
Background
Because the modularized multi-level converter has the advantages of easy expansion, self-commutation and high waveform quality, the flexible direct-current transmission system based on the modularized multi-level converter is widely applied to offshore wind power direct-current access occasions. Due to the difficulty in constructing large offshore platforms, a solution of connecting a plurality of small platforms with low voltage and large current in series at the offshore wind farm end is attracting attention. The current modular multilevel converter can be mainly divided into a half-bridge type, a full-bridge type, a half-bridge-full-bridge mixed type and a plurality of clamping types according to the type of the used sub-modules. Among different types of modular multilevel converters, a half-bridge modular multilevel converter has the lowest cost, each submodule only needs two switching tubes and two diodes, but the direct-current voltage output range of the half-bridge modular multilevel converter is narrow, and the capability of adjusting power by adjusting direct-current voltage in a series system is not achieved. The full-bridge modular multilevel converter has a direct-current voltage output range from a positive rated value to a negative rated value, but the number of required switching tubes and diodes is 2 times that of a half-bridge modular multilevel converter; in order to realize long-term stable operation in a direct-current voltage output range from a positive rated value to 0, the half-bridge and full-bridge hybrid modular multilevel converter also needs 70-80% of full-bridge submodules, and the number of required switching tubes and diodes is 1.7-1.8 times that of the half-bridge modular multilevel converter. The design goal of various clamping type modular multilevel converters is generally to realize the capability of clearing temporary short-circuit fault on the direct current side under the condition of adding fewer switching tubes, but the clamping type modular multilevel converter can also be used in the rectification occasion with wide direct current side voltage range, and the number of the required switching tubes is at least 1.25 times that of a half-bridge type modular multilevel converter, which still brings obvious cost increase.
Disclosure of Invention
The invention aims to provide a modular multilevel converter, which improves the structure of the existing modular multilevel converter, adopts a sub-module structure of unidirectional output current and asymmetric output voltage, and ensures that the converter obtains an output voltage rated value of a direct current side to be within a continuously adjustable output range from 0 under the condition that the consumption of switching devices is lower than that of a half-bridge converter.
The invention provides a modular multi-level rectifier, each phase of the modular multi-level rectifier comprises an upper bridge arm and a lower bridge arm, each bridge arm is respectively formed by cascading N identical submodules, the lower end of the upper bridge arm and the upper end of the lower bridge arm of each phase are respectively connected together through an inductor L, the connection point of the two inductors L of each phase is an AC bus ACU, ACV and ACW of the phase, the upper ends of the upper bridge arms of all the phases are connected together to form a DC positive bus DC +, the lower ends of the lower bridge arms of all the phases are connected together to form a DC negative bus DC-, the modular multi-level rectifier is characterized in that the upper bridge arm and the lower bridge arm are respectively formed by cascading N clamping type rectifier submodules, the value of N is an integer equal to or more than 1, and the value of N is determined according to the ratio relation between the rated output voltage of the modular multi-:
wherein, UarmRated voltage of bridge arm, UsmFor bridge arm submodule voltages, INT () is a rounding function.
The clamping type rectifier module in the modular multi-level rectifier comprises a first switch S1, a second switch S2, a third switch S3, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, a sixth diode D6, a seventh diode D7, a first capacitor C1 and a second capacitor C2; the collector of the first switch S1, the cathode of the first diode D1 and the anode of the fifth diode D5 are connected with each other to form a second terminal T2 of the clamping type rectifier sub-module; the emitter of the first switch S1, the anode of the first diode D1, the anode of the sixth diode D6 and the cathode of the first capacitor C1 are connected with each other; the cathode of the fifth diode D5, the anode of the first capacitor C1, the collector of the third switch S3, the cathode of the third diode D3 and the anode of the seventh diode D7 are connected with each other; the cathode of the sixth diode D6, the emitter of the third switch S3, the anode of the third diode D3, the cathode of the second capacitor C2 and the anode of the fourth diode D4 are connected with each other; the cathode of the seventh diode D7, the anode of the second capacitor C2, the collector of the second switch S2 and the cathode of the second diode D2 are connected with each other; and an emitter of the second switch S2, an anode of the second diode D2 and a cathode of the fourth diode D4 are connected with each other to form a first terminal T1 of the clamping type rectifier sub-module.
The modular multi-level rectifier provided by the invention has the advantages that:
the modular multilevel inverter of the invention effectively overcomes the defects of high cost of the existing full-bridge and clamping modular multilevel inverters and small adjustable range of the direct-current side voltage of the half-bridge modular multilevel inverter, wherein the sub-module has four voltage output states of positive, one-half positive, 0 and one-half negative, the dc side output voltage of the rectifier of the present invention can thus be continuously regulated between a positive nominal value and 0, meanwhile, compared with a half-bridge type converter, the half-bridge type converter is equivalent to only 3 switching tubes in two half-bridge submodules, each two half-bridge submodules are only added with 3 small-capacity diodes only used in an uncontrolled charging stage, the capacity of continuously adjusting the rated value of the direct-current side voltage to 0 under the rectification state can be realized on the premise that the consumption of a half-bridge type converter is only 0.75 time that of a switching tube, the capability of regulating the transmission power of the rectification side through the direct-current voltage in the offshore wind power series connection system can be realized at lower cost.
Drawings
Fig. 1 is a schematic structural diagram of a modular multi-level rectifier according to the present invention.
FIG. 2 is a schematic diagram of a clamped rectifier module of the present invention.
Fig. 3, 4, 5, 6, 7, 8, 9 and 10 are output voltage schematics of eight switching states of the clamp rectifier sub-module of the present invention.
Detailed Description
The structure of the modular multi-level rectifier is shown in figure 1, each phase of the modular multi-level rectifier comprises an upper bridge arm and a lower bridge arm, each bridge arm is formed by cascading N identical submodules, the lower end of the upper bridge arm and the upper end of the lower bridge arm of each phase are respectively connected together through an inductor L, the connection point of the two inductors L of each phase is an alternating current bus ACU, ACV and ACW of the phase, the upper ends of the upper bridge arms of all the phases are connected together to form a direct current positive bus DC +, the lower ends of the lower bridge arms of all the phases are connected together to form a direct current negative bus DC-, the bridge arm structure is characterized in that the upper bridge arm and the lower bridge arm are respectively formed by cascading N clamping type rectifier sub-modules, the value of N is an integer equal to or larger than 1, and the value of N is determined according to the ratio relation between the rated output voltage of the bridge arm of the modular multi-level rectifier and the rated voltage of the bridge arm sub-modules:
wherein, UarmRated voltage of bridge arm, UsmFor bridge arm submodule voltages, INT () is a rounding function.
The structure of the clamped rectifier module in the modular multi-level rectifier is shown in fig. 2, and the clamped rectifier module comprises a first switch S1, a second switch S2, a third switch S3, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, a sixth diode D6, a seventh diode D7, a first capacitor C1 and a second capacitor C2; the collector of the first switch S1, the cathode of the first diode D1 and the anode of the fifth diode D5 are connected with each other to form a second terminal T2 of the clamping type rectifier sub-module; the emitter of the first switch S1, the anode of the first diode D2, the anode of the sixth diode D6 and the cathode of the first capacitor C1 are connected with each other; the cathode of the fifth diode D5, the anode of the first capacitor C1, the collector of the third switch S3, the cathode of the third diode D3 and the anode of the seventh diode D7 are connected with each other; the cathode of the sixth diode D6, the emitter of the third switch S3, the anode of the third diode D3, the cathode of the second capacitor C2 and the anode of the fourth diode D4 are connected with each other; the cathode of the seventh diode D7, the anode of the second capacitor C2, the collector of the second switch S2 and the cathode of the second diode D2 are connected with each other; and an emitter of the second switch S2, an anode of the second diode D2 and a cathode of the fourth diode D4 are connected with each other to form a first terminal T1 of the clamping type rectifier sub-module.
The working principle and the working process of the invention are described in detail in the following with the accompanying drawings:
by selecting the proper rated alternating current port line voltage of the converter and the proper bridge arm circulating current, the bridge arm current always flows in from the second terminal T2 port and flows out from the first terminal T1 port of each submodule in the operation state of the converter. For example, for a nominal DC port voltage of UdcThe rated active power of the converter is P, the rated capacity of the converter is S, the voltage U of the rated alternating current port of the converter is UacThe requirements are satisfied:
let the DC port current of the converter be idcThree-phase alternating current is iu、iv、iwThe positive direction of current is as shown in fig. 1, and is set as follows:
the circulating current of the three-phase bridge arm can be set as follows:
in the bridge arm current control of the converter, i is setuc、ivc、iwcAnd the positive directions of the circulating currents are all from the positive bus to the negative bus.
Under the condition of meeting the rated alternating current port line voltage and proper bridge arm circulating current of the converter, the bridge arm current always flows from each bridge arm under the operation state of the converterThe second terminal T2 port of the submodule flows in, and the first terminal T1 port of the submodule flows out. The voltages of C1 and C2 are respectively E1 and E2, and both E1 and E2 are close to U in normal operationsmAnd/2, setting the average value as E, and controlling the submodules in the following modes and voltage output states when the current always flows into the port T2 and flows out of the port T1 of each submodule:
1) when the switch S1 is turned off, the switch S2 is turned off, and the switch S3 is turned off, as shown in fig. 3, the voltage between the sub-module ports T1 and T2 is-E, and the current preferentially flows through the capacitor with lower voltage to charge the capacitor;
2) when the switch S1 is turned on, S2 is turned off, and S3 is turned off, as shown in fig. 4, the voltage between the sub-module ports T1 and T2 is 0, and the current is higher than E2 at E1 to discharge C1 and charge C2;
3) when the switch S1 is turned off, S2 is turned on, and S3 is turned off, as shown in fig. 5, the voltage between the sub-module ports T1 and T2 is 0, and the current is lower than E2 at E1 to charge C1 and discharge C2;
4) when the switch S1 is turned off, the switch S2 is turned off, and the switch S3 is turned on, as shown in fig. 6, the voltage between the sub-module ports T1 and T2 is 0, and both capacitors are not charged and discharged;
5) when the switch S1 is turned on, the switch S2 is turned on, and the switch S3 is turned off, as shown in fig. 7, the voltage between the sub-module ports T1 and T2 is E, and the current preferentially flows through the capacitor with higher voltage to discharge the capacitor;
6) when the switch S1 is turned on, S2 is turned off, and S3 is turned on, as shown in fig. 8, the voltage between the sub-module ports T1 and T2 is E, and current flows through C1 to discharge it;
7) when the switch S1 is turned off, S2 is turned on, and S3 is turned on, as shown in fig. 9, the voltage between the sub-module ports T1 and T2 is E, and current flows through C2 to discharge it;
8) when the switch S1 is turned on, the switch S2 is turned on, and the switch S3 is turned on, as shown in fig. 10, the voltage between the sub-module ports T1 and T2 is 2E, and the current discharges both capacitors;
as described above, the port of the submodule can output four voltage states of 2E, E, 0 and E, and the voltage balance of the two capacitors can be realized.
For a bridge arm formed by sequentially cascading the T1 and T2 terminals of the N sub-module ports, the voltage state of the bridge arm can be changed between 2 NxE, … 2E, E, 0, -E … -NxE.
In one embodiment of the present invention, as shown in fig. 1, the modular multi-level rectifier includes U, V and W three phases, each phase is composed of two bridge arms and two inductors, the lower end of the upper bridge arm and the upper end of the lower bridge arm are connected together through one inductor, the midpoint of the inductor is the ac outgoing line, the upper end of the upper bridge arm is the dc positive outgoing line, and the lower end of the lower bridge arm is the dc negative outgoing line. The output voltage state of the submodule ports of each bridge arm is controlled, and the alternating current outlet line voltage and the direct current outlet line voltage can be respectively controlled. The rated direct current voltage of the converter is 160kV, the rated active power is 100MW, and the rated capacity is 111.8MVA, then the rated alternating current line voltage of the converter is selected to be 146kV, the rated bridge arm voltage is selected to be 234kV, and the rated bridge arm current effective value is 318.4A. Considering a single submodule rated at 3.6kV, each bridge arm contains 65 submodules, and each capacitor in each module is rated at 1.8 kV. S1, S2, S3, D4, D5, D6 and D7 in the submodule need to select devices with a current level equivalent to the current level of the submodule and a voltage level equivalent to half of the voltage level of the submodule, for example, a switching device with a rated voltage and current of 3300V/600A is selected for the submodule of the embodiment 3.6kV/318.4A after considering a safety margin. As can be seen from fig. 1, in the converter operating state, the bridge arm current always flows in from the port T2 of each submodule and flows out from the port T1, so that in the converter operating state, the bridge arm current does not flow through the diodes D1, D2 and D3, so that the diodes D1, D2 and D3 do not need to bear the bridge arm current in the operating state, and the rated currents of the diodes D1, D2 and D3 can be selected only according to the current in the uncontrolled rectifying and charging stage in the starting process. For example, the maximum value of the rectified charging current is not controlled to be 30A during the starting process, and D1 and D2 can select devices with the rated voltage and current of 3300V/60A.
Because the sub-modules of the rectifier have four voltage output states of positive, one-half positive, 0 and one-half negative, the output voltage of the direct current side of the rectifier can be continuously regulated between a positive rated value and 0, meanwhile, the rectifier is equivalent to only 3 switching tubes in two half-bridge sub-modules relative to a half-bridge type converter, only 3 small-capacity diodes only used in an uncontrolled charging stage are added to each two half-bridge sub-modules, and the capacity of regulating transmission power through the direct current voltage at the rectifying side in an offshore wind power series connection system can be realized at lower cost than that of the half-bridge type converter.
Claims (2)
1. A modular multi-level rectifier is disclosed, each phase of the modular multi-level rectifier comprises an upper bridge arm and a lower bridge arm, each bridge arm is respectively formed by cascading N identical submodules, the lower end of the upper bridge arm and the upper end of the lower bridge arm of each phase are respectively connected together through an inductor L, the connection point of the two inductors L of each phase is an AC bus ACU, ACV and ACW of the phase, the upper ends of the upper bridge arms of all the phases are connected together to form a DC positive bus DC +, the lower ends of the lower bridge arms of all the phases are connected together to form a DC negative bus DC-, the modular multi-level rectifier is characterized in that the upper bridge arm and the lower bridge arm are respectively formed by cascading N clamping rectifier submodules, the value of N is an integer equal to or more than 1, and the value of N is determined according to the ratio relation between the rated output voltage of the bridge arms of:
wherein, UarmRated voltage of bridge arm, UsmFor bridge arm submodule voltages, INT () is a rounding function.
2. The modular multilevel rectifier of claim 1, wherein the clamped rectifier sub-module comprises a first switch S1, a second switch S2, a third switch S3, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, a sixth diode D6, a seventh diode D7, a first capacitor C1, and a second capacitor C2; the collector of the first switch S1, the cathode of the first diode D1 and the anode of the fifth diode D5 are connected with each other to form a second terminal T2 of the clamping type rectifier sub-module; the emitter of the first switch S1, the anode of the first diode D1, the anode of the sixth diode D6 and the cathode of the first capacitor C1 are connected with each other; the cathode of the fifth diode D5, the anode of the first capacitor C1, the collector of the third switch S3, the cathode of the third diode D3 and the anode of the seventh diode D7 are connected with each other; the cathode of the sixth diode D6, the emitter of the third switch S3, the anode of the third diode D3, the cathode of the second capacitor C2 and the anode of the fourth diode D4 are connected with each other; the cathode of the seventh diode D7, the anode of the second capacitor C2, the collector of the second switch S2 and the cathode of the second diode D2 are connected with each other; and an emitter of the second switch S2, an anode of the second diode D2 and a cathode of the fourth diode D4 are connected with each other to form a first terminal T1 of the clamping type rectifier sub-module.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910829985.1A CN110601570A (en) | 2019-09-04 | 2019-09-04 | Many level of modularization current regulator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910829985.1A CN110601570A (en) | 2019-09-04 | 2019-09-04 | Many level of modularization current regulator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN110601570A true CN110601570A (en) | 2019-12-20 |
Family
ID=68857168
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910829985.1A Pending CN110601570A (en) | 2019-09-04 | 2019-09-04 | Many level of modularization current regulator |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110601570A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111293911A (en) * | 2020-02-10 | 2020-06-16 | 华北电力大学（保定） | Shift full-bridge modular multilevel converter |
| CN111654011A (en) * | 2020-05-20 | 2020-09-11 | 四川大学 | Direct-current fault clearing method for MMC asymmetric capacitance clamping submodule |
| CN113922682A (en) * | 2021-12-13 | 2022-01-11 | 四川大学 | Direct cascade type modular multilevel converter of three-phase bridge circuit |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105634315A (en) * | 2016-02-22 | 2016-06-01 | 清华大学 | One-way current type modular multilevel converter |
| CN106230283A (en) * | 2016-09-30 | 2016-12-14 | 广州供电局有限公司 | Sending end Multilevel Inverters for power one-way transmission occasion |
-
2019
- 2019-09-04 CN CN201910829985.1A patent/CN110601570A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105634315A (en) * | 2016-02-22 | 2016-06-01 | 清华大学 | One-way current type modular multilevel converter |
| CN106230283A (en) * | 2016-09-30 | 2016-12-14 | 广州供电局有限公司 | Sending end Multilevel Inverters for power one-way transmission occasion |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111293911A (en) * | 2020-02-10 | 2020-06-16 | 华北电力大学（保定） | Shift full-bridge modular multilevel converter |
| CN111654011A (en) * | 2020-05-20 | 2020-09-11 | 四川大学 | Direct-current fault clearing method for MMC asymmetric capacitance clamping submodule |
| CN111654011B (en) * | 2020-05-20 | 2021-04-13 | 四川大学 | Direct-current fault clearing method for MMC asymmetric capacitance clamping submodule |
| CN113922682A (en) * | 2021-12-13 | 2022-01-11 | 四川大学 | Direct cascade type modular multilevel converter of three-phase bridge circuit |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110224623B (en) | DC fault blocking modular multilevel converter and submodule | |
| CN105071425B (en) | A kind of Hybrid HVDC system based on LCC and MMC | |
| CN105634315A (en) | One-way current type modular multilevel converter | |
| CN110601570A (en) | Many level of modularization current regulator | |
| CN109873568B (en) | Multi-DC port converter and control method | |
| CN107834854A (en) | A kind of high-voltage large-capacity commutator transformer | |
| CN105227128B (en) | A kind of photovoltaic module multi-level converter and its control method | |
| CN111371336B (en) | Hybrid modular multilevel converter based on energy self-balancing circuit | |
| CN112865560B (en) | Multi-diode series back-to-back bridgeless three-level rectifier | |
| EP4113813A1 (en) | Power electronic apparatus for converting input ac into dc | |
| CN110535166A (en) | A kind of more drop point DC transmission systems of mixing series connection | |
| CN114665716A (en) | High-voltage direct-current transformer and system | |
| CN111900886B (en) | Flexible direct current transmission converter | |
| CN110995039B (en) | Low-loss modular multilevel converter and parameter design method thereof | |
| CN113489359A (en) | Submodule topology with direct-current fault clearing capability | |
| CN110994974B (en) | Low-loss modular multi-level direct current-direct current converter and submodule thereof | |
| CN108270356B (en) | Direct-current distribution network energy router based on PWM/diode hybrid rectification structure and control method thereof | |
| CN217984872U (en) | Hybrid modular multilevel converter | |
| CN217769504U (en) | Direct current offshore power transmission system | |
| CN114553020B (en) | Capacitor multiplexing type modular multilevel converter and control method thereof | |
| CN112865563B (en) | Three-port clamping type back-to-back bridgeless three-level rectifier | |
| CN112865561B (en) | Diode clamping type back-to-back bridgeless three-level rectifier | |
| CN113258797B (en) | Back-to-back type three-level rectifier of heterogeneous switching tube bridge arm | |
| CN113193768B (en) | Four-switch-tube series-type back-to-back three-level rectifier | |
| CN210041319U (en) | Power transmission system and wind power generation system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WD01 | Invention patent application deemed withdrawn after publication | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20191220 |