CN111953221A - Modular multilevel converter and converter station - Google Patents
Modular multilevel converter and converter station Download PDFInfo
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- CN111953221A CN111953221A CN202010774459.2A CN202010774459A CN111953221A CN 111953221 A CN111953221 A CN 111953221A CN 202010774459 A CN202010774459 A CN 202010774459A CN 111953221 A CN111953221 A CN 111953221A
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- 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
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- 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
- H02M7/505—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means
- H02M7/515—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only
- H02M7/521—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only in a bridge configuration
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- 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
- H02M1/00—Details of apparatus for conversion
- H02M1/0048—Circuits or arrangements for reducing losses
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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
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
The invention discloses a modular multilevel converter and a converter station, wherein the modular multilevel converter comprises three-phase bridge arms, each phase of bridge arm comprises an upper bridge arm and a lower bridge arm, the upper bridge arm and the lower bridge arm are provided with a plurality of cascaded converter sub-modules, each converter sub-module comprises a first full-control switch module, a second full-control switch module, a buffer circuit and a first capacitor, and the first full-control switch module and the second full-control switch module are connected in series to form a switch branch; the switch branch circuit, the buffer circuit and the first capacitor are connected in parallel; the first full-control switch module and the second full-control switch module both comprise an IGCT device and a first diode connected with the IGCT device in anti-parallel. The converter is provided with the IGCT device, so that the converter and the load switch are integrated in one converter station, the overall size and cost of the converter station are reduced, the high integration of the converter station is realized, the reliability of the converter station is high, and the converter station can be widely applied to a flexible direct-current transmission system.
Description
Technical Field
The invention belongs to the field of power transmission, and particularly relates to a modular multilevel converter and a converter station.
Background
Flexible dc transmission has become the most potential new power transmission mode at present, and has been applied to large-capacity power transmission systems. The modular multilevel converter is the most mainstream topology structure at present. Most of the currently put-into-operation flexible direct-current transmission projects adopt a modular multilevel converter based on an Insulated Gate Bipolar Transistor (IGBT), but the realization of clearing direct-current faults is very difficult, and very large direct-current short-circuit fault current is often generated when the direct-current short-circuit fault occurs, so that the direct-current short-circuit fault current needs to be broken, a direct-current circuit breaker with very large current breaking capacity is needed, and the direct-current circuit breaker is high in manufacturing cost and very large in size. Thus, as shown in fig. 1, the converter stations employ IGBT-based modular multilevel converters, and the converters and the circuit breakers are placed in two separate converter stations, respectively.
Therefore, how to provide a modular multilevel converter and realize the functions of integrated conversion and switch integration of the converter station becomes an urgent technical problem to be solved.
Disclosure of Invention
In order to solve the problems, the invention provides a modular multilevel converter and a converter station, which improve the reliability of the converter and realize the functions of integration of conversion and switch integration of the converter station.
The invention aims to provide a modular multilevel converter, which comprises three-phase bridge arms, wherein each phase of bridge arm comprises an upper bridge arm and a lower bridge arm, the upper bridge arm and the lower bridge arm are provided with a plurality of cascaded converter sub-modules, each converter sub-module comprises a first full-control switch module, a second full-control switch module, a buffer circuit and a first capacitor, wherein,
the first full-control switch module and the second full-control switch module are connected in series to form a switch branch circuit;
the switch branch circuit, the buffer circuit and the first capacitor are connected in parallel;
the first full-control switch module and the second full-control switch module both comprise an IGCT device and a first diode connected with the IGCT device in anti-parallel.
Further, the second fully-controlled switch module is connected in parallel to the output end of the converter submodule.
Further, the cathode of the IGCT device in the first fully-controlled switch module in the converter sub-module is connected with the anode of the IGCT device in the second fully-controlled switch module.
Further, the snubber circuit includes a first inductor, a first resistor, a second diode, and a second capacitor, wherein,
the first end of the first inductor is connected with the first end of the first capacitor and the first end of the first resistor respectively, and the second end of the first inductor is connected with the first fully-controlled switch module and the anode of the second diode respectively;
the cathode of the second diode is respectively connected with the second end of the first resistor and the first end of the second capacitor;
and the second end of the second capacitor is respectively connected with the second fully-controlled switch module and the second end of the first capacitor.
Another object of the invention is to provide a converter station comprising a modular multilevel converter as described above, a load switch and a first reactor, wherein,
the modular multilevel converter is connected with one end of the load switch;
and the other end of the load switch is connected with one end of the first reactor.
Further, the modular multilevel converter further comprises a direct current side and an alternating current side, wherein,
the direct-current side anode of the modular multilevel converter is connected with a direct-current line after being sequentially connected with a load switch and a first reactor;
and the alternating current side of the modular multilevel converter is connected with an alternating current power grid.
Furthermore, the IGCT devices in all the first fully-controlled switch modules and the second fully-controlled switch modules in the modular multilevel converter are used for controlling the IGCT devices in the first fully-controlled switch modules to be locked and the IGCT devices in the second fully-controlled switch modules to be switched on when the direct-current line has a short-circuit fault, so that the alternating-current power grid is in a three-phase short-circuit state, the direct-current port potential of the direct-current line is zero, and finally the fault current stops rising.
Further, the first reactor is a smoothing reactor.
Furthermore, the load switch is a rated load switch and is used for switching off and cutting off the fault current when the fault current of the direct current line reaches the rated current value of the load switch.
Further, the rated load switch is a mechanical load switch, an electronic load switch or a hybrid load switch.
Compared with an IGBT, the IGCT has very high surge current bearing capacity, on-state current capacity, forward blocking voltage capacity and reliability and very low on-state voltage drop, so that the modular multilevel converter has the advantages of large current, high blocking voltage, high reliability, compact structure, low conduction loss and the like.
Furthermore, the converter station can integrate the modular multilevel converter and the load switch into one station, so that the overall size and cost of the converter station are greatly reduced, high integration and high economy are realized, and the converter station can be widely applied to a future flexible direct-current transmission system.
In addition, the IGCT device in the first fully-controlled switch module is controlled to be locked, the IGCT device in the second fully-controlled switch module is controlled to be switched on, and the fault current can be effectively stopped from rising, so that the load switch only needs to break the direct current with the magnitude of the rated current, and the volume, the using amount and the cost required by the load switch are greatly reduced. And only a smoothing reactor is needed in the converter station, the inductance value of the smoothing reactor is small, and the current limiting function is not needed to be considered.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 shows a schematic structure of a converter station and a circuit breaker in the prior art;
fig. 2 shows a schematic structural diagram of a modular multilevel converter according to an embodiment of the invention;
fig. 3 shows a schematic structural diagram of a converter station in an embodiment of the invention;
fig. 4 shows U in a converter station in an embodiment of the inventionMMC、UDCAnd iDCThe variation profile during control.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 2, an embodiment of the present invention provides a modular multilevel converter, which includes three-phase bridge arms, each phase of bridge arm includes an upper bridge arm and a lower bridge arm, and the upper bridge arm and the lower bridge arm are provided with a plurality of cascaded converter sub-modules, where n converter sub-modules in the upper bridge arm of each phase of bridge arm are respectively shown in fig. 2: SMap1, SMap2 … … SMapn, SMbp1, SMbp2 … … SMbpn, SMcp1, SMcp2 … … SMcpn. The number of the current converter sub-modules in the lower bridge arm of each phase of bridge arm is n respectively, and in fig. 2, the number is respectively as follows: SMan1, SMan2 … … SMann, SMbn1, SMbn2 … … SMbpnn, SMcn1, SMcn2 … … SMcnn. Further, the converter submodule comprises a first full-control type switch module, a second full-control type switch module, a buffer circuit and a first capacitor. The first fully-controlled switch module comprises an Integrated Gate Commutated Thyristor (IGCT) device Sxi1And a first diode D connected in anti-parallel therewithxi1(ii) a The second fully-controlled switch module comprises an IGCT device Sxi2And a first diode D connected in anti-parallel therewithxi2(ii) a The first full-control switch module and the second full-control switch module are connected in series to form a switch branch circuit; the switch branch circuit, the buffer circuit and the first capacitor CxiAre connected in parallel with each other. Further, when the first fully-controlled switch module and the second fully-controlled switch module are connected in series, the IGCT device Sxi1And IGCT device Sxi2In the same direction, i.e. the IGCT device Sxi1And the IGCT device Sxi2Is connected with the anode of (2). The first fully-controlled switch module and the second fully-controlled switch module in the modular multilevel converter adopt IGCT devices,compared with an IGBT, the IGCT has very high surge current bearing capacity, on-state current capacity, forward blocking voltage capacity and reliability and also has very low on-state voltage drop, so that the modular multilevel converter has the advantages of large current, high blocking voltage, high reliability, compact structure, low conduction loss and the like.
In this embodiment, each first diode connected in anti-parallel with the IGCT device can effectively reverse cut off the fault current, thereby protecting the IGCT device.
More specifically, as shown in fig. 2, the second fully-controlled switch module is connected in parallel to the output end of the converter sub-module, and the plurality of converter sub-modules on the upper bridge arm and the lower bridge arm are connected through respective output ends. Further, the buffer circuit comprises a first inductor LxisA first resistor RxisA second diode DxisAnd a second capacitor CxisWherein the first inductor LxisAnd respectively with the first capacitor CxiFirst terminal and first resistor RxisA second end of the first diode is respectively connected with the first full-control type switch module and the second diode DxisThe positive electrode of (1) is connected; the cathode of the second diode is connected with the first resistor RxisSecond terminal and second capacitor CxisIs connected with the first end of the first connecting pipe; second capacitor CxisThe second end of the first capacitor is respectively connected with the second full-control type switch module and the first capacitor CxiIs connected to the second end of the first housing. The first end of the first capacitor Cxi is a positive electrode, the second end is a negative electrode, and the voltage is represented by Vc. By adopting the buffer circuit, the rise rate of current or voltage on the first fully-controlled switch module and/or the second fully-controlled switch module can be effectively inhibited when the modular multilevel converter normally works. When the modular multilevel converter works in a short-circuit fault state of a direct-current line, the buffer circuit is in a bypass state during fault processing due to the adoption of a method that an IGCT device in the first fully-controlled switch module is locked and an IGCT device in the second fully-controlled switch module is conducted.
In this embodiment, the upper bridge arm and the lower bridge arm of each phase of bridge arm are further provided with a second reactor (not shown in fig. 2-3), and the second reactor is connected in series with the plurality of converter sub-modules cascaded on the corresponding bridge arm.
As shown in fig. 3, a converter station is further introduced in the embodiment of the present invention, and the converter station includes the above modular multilevel converter, as well as a load switch and a first reactor, where the modular multilevel converter includes a dc side and an ac side; the positive pole of the DC side of the modular multilevel converter is connected with one end of the load switch, the other end of the load switch is connected with one end of the first reactor, and the other end of the first reactor is connected with a DC line. Further, the negative electrode of the modular multilevel converter and the other end of the first reactor form a direct current port of the converter station, that is, the direct current port of the converter station, and the converter station is connected with a direct current line through the direct current port. And an alternating current port of the converter station is formed on the alternating current side of the modular multilevel converter and is connected with an alternating current power grid. In the embodiment of the invention, the converter and the load switch are integrated in one converter station, so that the overall size and cost of the converter station are greatly reduced, high integration and high economy are realized, and the converter station can be widely applied to a future flexible direct current transmission system. In addition, the modular multilevel converter is applied to the converter station, so that the converter station based on the IGCT can realize the function of self-clearing of the direct-current fault when facing the direct-current short-circuit fault, and can well limit the rise of the direct-current short-circuit fault current.
In fig. 3, the load switch is a rated load switch. And the device is used for switching off and cutting off the fault current when the fault current of the direct current line reaches the rated current value of the load switch. Because the IGCT device in the first fully-controlled switch module is controlled to be locked, the IGCT device in the second fully-controlled switch module is switched on, and the fault current can be effectively stopped to rise. The load switch only needs to break the direct current with the rated current, so that the volume, the consumption and the cost required by the load switch are greatly reduced. Further, the rated load switch is a mechanical load switch, an electronic load switch or a hybrid load switch. The first reactor is a smoothing reactor. Because the modular multilevel converter can directly limit the rise of fault current in the short-circuit fault of a direct-current line, the converter in the embodiment of the invention does not need to be provided with a reactor with a large inductance value for current limiting, and only uses the reactor for level wave. Therefore, the inductance value of the first reactor in the embodiment of the invention is small, and the current limiting function is not required to be considered. However, since the IGBT-MMC (Modular Multilevel Converter) cannot limit the rapid rise of the fault current during the fault, a reactor with a large inductance value is required for current limiting, and the reactor is also used for smoothing the current.
An embodiment of the present invention further provides a control method for the converter station, where a control process of the control method specifically includes the following steps:
1) time t 0: assuming that a dc line short fault occurs at time t0, the fault current caused by the dc line short fault starts to rise rapidly.
2) time t 1: and detecting the moment when the short-circuit fault occurs and the sub-module of the converter acts in a protection mode. When the short-circuit fault of the direct-current line is detected, IGCT devices S of first fully-controlled switch modules in all converter sub-modules in the modular multilevel converterxi1IGCT device S of a latching, second fully-controlled switching modulexi2And conducting. Specifically, the time period from t0 to t1 is the delay time after the short-circuit fault occurs in the dc line, wherein the time period from t0 to t1 is 0.3ms (millisecond).
When a short-circuit fault occurs in a direct-current line, IGCT devices S of first full-control type switch modules in all converter sub-modules of a modular multilevel converter in a converter stationxi1IGCT device S of a latching, second fully-controlled switching modulexi2And conducting, so that an alternating current power grid connected with the alternating current side of the modular multilevel converter is in a three-phase short circuit state, specifically, the three-phase short circuit is equivalent to that of a second reactor on all bridge arms of the modular multilevel converter, the potential of a direct current port of a converter station is equivalent to zero, meanwhile, the potential of the direct current side of the modular multilevel converter is also zero, and the fault current stops at the momentStopping rising.
3) time t 2: when the load switch cuts off the fault current, the fault current of the direct current line short-circuit fault passing through the load switch reaches the maximum value. the time period from t1 to t2 is the time when the load switch receives the action command and is separated from the switch, and the time period from t1 to t2 is about 3 ms. After the load switch is switched off, the dc line and the modular multilevel converter are isolated, the fault current starts to decay, and from there the dc line starts to free. Further, the maximum value of the fault current is the rated current value of the load switch.
4) time t 3: IGCT device S of second fully-controlled switch module in all converter sub-modules in modular multilevel converterxi2The latching moment of (c). After the load switch breaks the fault current, the voltage of the direct current side port of the modular multilevel converter is not required to be clamped through active short circuit of the IGCT device. Therefore, the IGCT device can be controlled to be turned off when the current of each phase bridge arm crosses zero or is small, the three-phase short-circuit state of the alternating current power grid is finished, the time period from t2 to t3 is the time for controlling the locking of the modular multilevel converter, and the time period from t2 to t3 is less than 10 ms. In the embodiment of the invention, the small current is that the current on each phase bridge arm is not more than the preset value of the repeated turn-off current of the IGCT device, the preset value of the repeated turn-off current of the IGCT device is the maximum repeated turn-off current capacity of the IGCT, and the maximum repeated turn-off current capacity of the four-inch IGCT device with the highest market share can be 4.5kA (kiloamperes), but is not limited to 4.5kA, 5kA, 6kA and the like.
5) time t 4: when the modularized multi-level converter is unlocked, all IGCT devices in all converter sub-modules are turned on again, namely all IGCT devices S are enabledxi1And IGCT device Sxi2And conducting. The voltage of the modular multilevel converter is slowly restored to a normal operation state from a locking state. The process of recovering the voltage often requires one to two cycles, for a total of about 40 ms. But only the voltage recovery is finished before the load switch is reclosed. The voltage is normal operation of the modular multilevel converterThe rated dc voltage of (1).
6) time t 5: and controlling the reclosing time of the load switch. At this point the modular multilevel converter has been unlocked and restored to the voltage at normal operation. the length of the time period t 2-t 5 is the time for the DC line to detach, so that the length of the time period t 2-t 5 is about 300 ms.
7) time t 6: and at the moment when the load switches complete superposition, the modular multilevel converter recovers to transmit power to the direct current side. the time period from t5 to t6 is the reclosing time of the load switch, and the time period from t5 to t6 is about 15-20 ms for the mechanical load switch.
Through the control process, the voltage U of the modular multilevel converterMMCAnd voltage U of DC port of DC lineDCAnd current iDCThe variation of (a) is shown in fig. 4. In the control process, the length and the time length of each time period effectively indicate that the converter station in the embodiment of the invention can quickly process and recover the short-circuit fault of the direct current line, and the reliability is higher.
The modular multilevel converter provided with the IGCT device and the load switch are arranged in one converter station together, so that the structure is more compact, and the converter station has the functions of conversion and switching.
Although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A modular multilevel converter comprises three-phase bridge arms, each phase of bridge arm comprises an upper bridge arm and a lower bridge arm, the upper bridge arm and the lower bridge arm are provided with a plurality of cascaded converter sub-modules, the modular multilevel converter is characterized in that the converter sub-modules comprise a first full-control switch module, a second full-control switch module, a buffer circuit and a first capacitor, wherein,
the first full-control switch module and the second full-control switch module are connected in series to form a switch branch circuit;
the switch branch circuit, the buffer circuit and the first capacitor are connected in parallel;
the first full-control switch module and the second full-control switch module both comprise an IGCT device and a first diode connected with the IGCT device in anti-parallel.
2. The modular multilevel converter according to claim 1, wherein the second fully controlled switch module is connected in parallel at the output of the converter sub-module.
3. The modular multilevel converter according to claim 2, wherein the cathode of the IGCT device in a first fully controlled switch module in the converter sub-module is connected to the anode of the IGCT device in a second fully controlled switch module.
4. The modular multilevel converter according to any of claims 1-3, wherein the snubber circuit comprises a first inductor, a first resistor, a second diode, and a second capacitor, wherein,
the first end of the first inductor is connected with the first end of the first capacitor and the first end of the first resistor respectively, and the second end of the first inductor is connected with the first fully-controlled switch module and the anode of the second diode respectively;
the cathode of the second diode is respectively connected with the second end of the first resistor and the first end of the second capacitor;
and the second end of the second capacitor is respectively connected with the second fully-controlled switch module and the second end of the first capacitor.
5. A converter station comprising a modular multilevel converter according to claim 1, load switches and first reactors, wherein,
the modular multilevel converter is connected with one end of the load switch;
and the other end of the load switch is connected with one end of the first reactor.
6. A converter station according to claim 5, characterized in that said modular multilevel converter further comprises a DC side and an AC side, wherein,
the direct-current side anode of the modular multilevel converter is connected with a direct-current line after being sequentially connected with a load switch and a first reactor;
and the alternating current side of the modular multilevel converter is connected with an alternating current power grid.
7. The converter station according to claim 6, wherein the IGCT devices in all the first fully-controlled switch module and the second fully-controlled switch module of the modular multilevel converter are configured to control the IGCT devices in the first fully-controlled switch module to be locked and the IGCT devices in the second fully-controlled switch module to be turned on when the short-circuit fault occurs in the DC line, so that the AC grid is in a three-phase short-circuit state and the DC port potential of the DC line is zero, and finally the fault current stops rising.
8. A converter station according to claim 7, characterized in that said first reactor is a smoothing reactor.
9. A converter station according to claim 8, characterized in that said load switches are rated load switches for switching off the fault current when the fault current of the DC line reaches the rated current value of the load switches.
10. A converter station according to claim 9, characterized in that said rated load switches are mechanical, electronic or hybrid load switches.
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| CN112909986A (en) * | 2021-02-05 | 2021-06-04 | 清华大学 | Modular multi-level converter submodule and control method thereof |
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| US20170047727A1 (en) * | 2014-02-27 | 2017-02-16 | Nr Electric Co., Ltd | Direct-current power transmission protection device, converter and protection method |
| CN104617757A (en) * | 2015-01-30 | 2015-05-13 | 天津大学 | Improved overvoltage preventing type MMC current converter structure having direct-current fault current-limiting capacity |
| CN104767185A (en) * | 2015-03-20 | 2015-07-08 | 浙江大学 | Convertor station having direct current fault clearance capacity and control method of convertor station |
| CN108886320A (en) * | 2016-04-08 | 2018-11-23 | Abb瑞士股份有限公司 | Converter unit including the energy converter in parallel with clamper inductor |
| CN106026048A (en) * | 2016-07-15 | 2016-10-12 | 浙江大学 | DC grid fault handling strategy based on in-situ detection and in -situ protection |
| CN107947613A (en) * | 2018-01-02 | 2018-04-20 | 清华大学 | A kind of high-voltage large-capacity modularization multi-level converter based on IGCT |
| CN108829989A (en) * | 2018-06-22 | 2018-11-16 | 国网江苏电力设计咨询有限公司 | Flexible direct current system direct current side major loop parameter design method containing superconducting direct current limiter |
| CN108616223A (en) * | 2018-07-03 | 2018-10-02 | 清华大学 | A kind of modularization multi-level converter and fault handling method based on IGCT |
| CN111181416A (en) * | 2020-01-09 | 2020-05-19 | 华北电力大学 | Modular multilevel converter and direct-current fault clearing method |
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| CN112909986A (en) * | 2021-02-05 | 2021-06-04 | 清华大学 | Modular multi-level converter submodule and control method thereof |
| CN112909986B (en) * | 2021-02-05 | 2023-08-22 | 清华大学 | Modularized multi-level converter sub-module and control method thereof |
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