CN112953277A - Five level of modularization many level transverter MMC presss from both sides submodule topological structure - Google Patents

Five level of modularization many level transverter MMC presss from both sides submodule topological structure Download PDF

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CN112953277A
CN112953277A CN202110261287.3A CN202110261287A CN112953277A CN 112953277 A CN112953277 A CN 112953277A CN 202110261287 A CN202110261287 A CN 202110261287A CN 112953277 A CN112953277 A CN 112953277A
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module
sub
submodule
bipolar transistor
insulated gate
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CN112953277B (en
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江耀曦
束洪春
邵宗学
杨竞及
田鑫萃
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Kunming University of Science and Technology
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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
    • H02M7/487—Neutral point clamped inverters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
    • H02H3/087—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current for dc applications
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
    • H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
    • H02H7/122—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for inverters, i.e. dc/ac converters
    • 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
    • H02M1/32—Means for protecting converters other than automatic disconnection

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  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

The invention relates to a modular multilevel converter MMC five-level clamping submodule topological structure, and belongs to the technical field of flexible direct-current transmission. The bridge arm type three-phase power supply comprises an A, B, C three-phase circuit composed of sub-modules, wherein each phase comprises an upper bridge arm and a lower bridge arm, each bridge arm is composed of N sub-modules, and two bridge arm reactors are arranged between the upper bridge arm and the lower bridge arm of the A, B, C three-phase circuit; the submodule comprises an upper submodule part and a lower submodule part which are connected through a diode, a voltage negative electrode port of the upper submodule part is connected to a voltage positive electrode port of the lower submodule part, a voltage negative electrode port of the lower submodule part is connected with an anode of the diode, and the upper submodule part is connected with a cathode of the diode. The invention has better direct current fault clearing capacity and better voltage-sharing effect, and is beneficial to the quick restart of the MMC.

Description

Five level of modularization many level transverter MMC presss from both sides submodule topological structure
Technical Field
The invention relates to a modular multilevel converter MMC five-level clamping submodule topological structure, in particular to a modular multilevel converter MMC five-level clamping submodule topological structure with a function of clearing direct current faults, and belongs to the technical field of flexible direct current transmission.
Background
The modular multilevel converter has the advantages of easy expansion, good output waveform quality, comprehensive fault protection, strong recovery capability, low loss, strong unbalanced operation capability and the like by virtue of the modular structure, and is widely applied to the field of high-voltage direct-current transmission. The modular multilevel converter topology based on the half-bridge submodule is one of voltage source type converter topologies with great technical advantages, and compared with other power electronic converters, the modular multilevel converter topology based on the half-bridge submodule has the technical advantages of easy expansibility, high voltage and current output waveform quality, low harmonic content, no need of dynamic voltage sharing among power devices and the like in the field of medium-high voltage electric energy conversion application. However, the freewheeling effect of the diode may cause the lack of the capability of suppressing the short-circuit fault current on the dc side when applied to high-voltage dc transmission, which is not favorable for using an overhead line with lower cost. The ac/dc breaker is a feasible solution for isolating dc faults, but this solution requires additional equipment and devices to be installed on the ac side and the dc side of the system, which results in increased system cost, power consumption and floor space. In addition, the response speed of the alternating current circuit breaker is low, and the technology of the direct current circuit breaker in high-voltage and high-power application occasions is still not mature, and the direct current circuit breaker is still in the development and experiment stages. Therefore, improving the MMC topology becomes the most effective means of blocking dc fault currents. Compared with the traditional half-bridge sub-module, the full-bridge sub-module can output a negative level and has fault current clearing capacity, but the cost is relatively high and is twice of that of a half bridge.
The sub-module capacitor is the basis for realizing the AC/DC energy transfer of the MMC, and the condition for keeping the capacitor voltage balance of each sub-module is the necessary condition for stable operation of the MMC. The traditional submodule capacitor voltage sequencing algorithm is large in calculation amount and large in power device switching loss, and the voltage-sharing sequencing algorithm needs to monitor all submodule capacitors.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a five-level clamping submodule topological structure of a modular multilevel converter MMC, and when a direct-current short-circuit fault occurs, a module capacitor can be introduced into a fault loop, so that the fault current is blocked quickly, the quick restart of the MMC is facilitated, and the problem is solved.
Compared with the prior art, the MMC submodule topology with the function of clearing the direct current fault current has great advantages in cost, operation loss is relatively low, and complexity of a system can not be increased.
The technical scheme of the invention is as follows: a five-level clamping submodule topological structure of a modular multilevel converter MMC comprises an A, B, C three-phase circuit composed of submodules, wherein each phase comprises an upper bridge arm and a lower bridge arm, each bridge arm is composed of N submodules, and two bridge arm reactors are arranged between the upper bridge arm and the lower bridge arm of a A, B, C three-phase circuit.
The upper output end of the 1 st sub-module of the upper bridge arm of the A-phase circuit is connected with the positive electrode of a direct current terminal bus, the lower output end of the 1 st sub-module of the A-phase circuit is connected with the upper output end of the 2 nd sub-module, the upper output end of the 2 nd sub-module is connected with the lower output end of the first sub-module, the lower output end of the 3 rd sub-module is connected with the lower output end of the 3 rd sub-module, the upper output end of the i-th sub-module is connected with the lower output end of the i-1 th sub-module, the lower output end of the i-th sub-module is connected with the upper output end of the i +1 th sub-module, the upper output end of the Nth sub-module of the upper bridge arm is connected with.
The upper output end of the 1 st sub-module of the lower bridge arm of the A-phase circuit is connected with the lower bridge arm reactor, the lower output end of the 1 st sub-module of the lower bridge arm is connected with the upper output end of the 2 nd sub-module of the lower bridge arm, the upper output end of the ith sub-module of the lower bridge arm is connected with the lower output end of the (i-1) th sub-module, the lower output end of the ith sub-module of the lower bridge arm is connected with the upper output end of the (i + 1) th sub-module, for the Nth sub-module of the lower bridge arm, the upper output. B. The connection mode of the submodules of the C two-phase circuit is the same as that of the A phase circuit.
The power supply module comprises an upper half part of a submodule and a lower half part of the submodule, wherein the upper half part of the submodule and the lower half part of the submodule are connected through a high-power diode, a voltage negative electrode port of the upper half part of the submodule is connected to a voltage positive electrode port of the lower half part of the submodule, a voltage negative electrode port of the lower half part of the submodule is connected with an anode of the high-power diode, and the upper half part of the.
The upper half part of the sub-module comprises a half-bridge sub-module I and a half-bridge sub-module II which are connected in a nested manner;
the half-bridge submodule I is composed of an insulated gate bipolar transistor T1And its anti-parallel diode D1Insulated gate bipolar transistor T2And its anti-parallel diode D2Capacitor C1Forming;
the half-bridge submodule II is composed of an insulated gate bipolar transistor T3And its anti-parallel diode D3Insulated gate bipolar transistor T4And its anti-parallel diode D4Capacitor C2Forming;
t of half-bridge submodule II module4The collector of the half-bridge submodule I is connected with a capacitor C1Negative electrode on the right, T4Emitter and T2Is connected to the negative port of the upper half, T1Emitter and T2The collector electrodes of the half-bridge submodule I are connected together to serve as an anode port of the upper half part of the submodule, and a voltage anode port of the half-bridge submodule I is a voltage anode output end of a topological structure.
The lower half part of the sub-module comprises a half-bridge sub-module III and a half-bridge sub-module IV which are nested and connected;
the half-bridge submodule III is composed of an insulated gate bipolar transistor T5And its anti-parallel diode D5Insulated gate bipolar transistor T6And its anti-parallel diode D6Insulated gate bipolar transistor T7And its anti-parallel diode D7Capacitor C3Form, an insulated gate bipolar transistor T6And its anti-parallel diode D6Formed switch group and insulated gate bipolar transistor T7And its anti-parallel diode D7The formed switch groups are connected in series in an anti-reverse manner;
the half-bridge sub-module IV is composed of an insulated gate bipolar transistor T8And its anti-parallel diode D8Insulated gate bipolar transistor T9And its anti-parallel diode D9Capacitor C4Forming;
insulated gate bipolar transistor T of half-bridge submodule IV module9The collector of the half-bridge submodule is connected with a capacitor C of the half-bridge submodule III3Right negative, insulated gate bipolar transistor T9Emitter and insulated gate bipolar transistor T7The emitting electrodes of the two-way bipolar transistor are connected to be used as a negative electrode port of the lower half part of the submodule, and the two-way bipolar transistor T is an insulated gate bipolar transistor5Emitter and insulated gate bipolar transistor T6The collector electrodes of the sub-modules are connected together to serve as an anode port of the lower half part of the sub-module, and a voltage cathode port of the lower half part of the sub-module is a voltage cathode output port of the topological structure.
The insulated gate bipolar transistor T1And an insulated gate bipolar transistor T2In opposite switching states, controls the capacitor C1And a shunt, an insulated gate bipolar transistor T3And an insulated gate bipolar transistor T4In opposite switching states, control C2Can output 0, Uc，2UcThree levels.
The insulated gate bipolar transistor T6And an insulated gate bipolar transistor T7Is in the same switching state as the insulated gate bipolar transistor T5In opposite switching states, controls the capacitor C3Said insulated gate bipolar transistor T8And an insulated gate bipolar transistor T8In opposite switching states, two C4Can output 0, Uc，2UcThree levels.
MMC five-level clamping submodule with function of clearing direct-current fault is connected in series with upper portion and lower portion and can independently output 0, Uc，2Uc，3Uc，4UcFive voltage levels, the diode is connected with the upper and lower two-part circuits and connected with the sub-circuitLower input terminal of module and capacitor C1Between positive stages, diode D when submodule is normally switched in10And cutting off in the reverse direction. The capacitor voltage balance can be realized through a sequencing algorithm under NLM modulation, and a closed-loop voltage-sharing controller does not need to be added. Submodule output voltage UsmThe relationship with the sub-module capacitance voltage is as follows:
Usm＝Usm1+Usm2＝P1 Uc1+P1 P3 Uc2+P5 Uc3+P5 P8 Uc4
in the formula P1、P3And P5，P8Respectively, the trigger signal of the corresponding switch tube takes the value of 0 or 1, Usm1For the output of the upper half of the submodule, Usm2Is output from the lower half of the submodule, UsmAnd the output is the integral output after the upper part and the lower part of the submodule are connected in series. In the aspect of capacitor voltage balance control, the topological structure of the MMC five-level clamping submodule with the function of clearing fault current can be equivalent to the series connection of four HBSM, and the control difficulty is the same as that of the HBSM.
In normal operation, the MMC five-level clamp submodule operates in the following 9 normal switching modes.
Mode 1: switch tube T2，T6，T7Conduction, T1，T3，T4And T5，T8，T9When the module is cut off, the current flows into the module from the input end of the module in the positive direction, and the current path is T2→T6→D7The current positively flows into the submodule from the lower input end of the submodule, and the current path is T7→D6→D2. Capacitor C1，C2，C3，C4All are bypassed, and the MMC five-level clamping submodule cuts off the output voltage to be 0.
Mode 2: switch tube T1，T4And T6，T7Conduction, T2，T3，T5，T8，T9When the module is cut off, the current flows into the module from the input end of the module in the positive direction, and the current path is D1→C1→T4→T6→D7The current positively flows into the submodule from the lower input end of the submodule, and the current path is T7→D6→D4→C1→T1. Capacitor C1Introduction of C2，C3，C4Are all bypassed, and the output voltage of the MMC five-level clamping submodule is Uc1。
Mode 3: switch tube T2And T5，T9Conduction, T1，T3，T4，T6，T7，T8When the module is cut off, the current flows into the module from the input end of the module in the positive direction, and the current path is T2→D5→C3→T9The current positively flows into the submodule from the lower input end of the submodule, and the current path is D9→C3→T5→D2. Capacitor C3Introduction of C1，C2，C4Are all bypassed, and the output voltage of the MMC five-level clamping submodule is Uc3。
Mode 4: switch tube T1，T4And T5，T9Conduction, T2，T3，T6，T7，T8When the module is cut off, the current flows into the module from the input end of the module in the positive direction, and the current path is D1→C1→T4→D5→C3→T9The current positively flows into the submodule from the lower input end of the submodule, and the current path is D9→C3→T5→D4→C1→T1. Capacitor C1，C3Introduction of C2，C4Are all bypassed, and the output voltage of the MMC five-level clamping submodule is Uc1+Uc3。
Mode 5: switch tube T1，T3And T6，T7Conduction, T2，T4，T5，T8，T9When the module is cut off, the current flows into the module from the input end of the module in the positive direction, and the current path is D1→C1→D3→C2→T6→D7The current positively flows into the submodule from the lower input end of the submodule, and the current path is T7→D6→C2→T3→C1→T1. Capacitor C1，C2Introduction of C3，C4By-pass, the output voltage of the MMC five-level clamping submodule is Uc1+Uc2。
The upper input end flows into the sub-module, and the current path is T2→D5→C3→D8→C4The current positively flows into the sub-module from the lower input end of the sub-module, and the current path is C4→T8→C3→T5→D2. Capacitor C3，C4Introduction of C1，C2By-pass, the output voltage of the MMC five-level clamping submodule is Uc3+Uc4。
Mode 7: switch tube T1，T3And T5,T9Conduction, T2，T4，T6，T7，T8When the module is cut off, the current flows into the module from the input end of the module in the positive direction, and the current path is D1→C1→D3→C2→D5→C3→T9The current positively flows into the submodule from the lower input end of the submodule, and the current path is D9→C3→T5→C2→T3→C1→T1. Capacitor C1，C2，C3Introduction of C4By-pass, the output voltage of the MMC five-level clamping submodule is Uc1+Uc2+Uc3。
Mode 8: switch tube T1，T4And T5,T8Conduction, T2，T3，T4，T6，T7，T9When the module is cut off, the current flows into the module from the input end of the module in the positive direction, and the current path is D1→C1→T4→D5→C3→D8→C4The current positively flows into the sub-module from the lower input end of the sub-module, and the current path is C4→T8→C3→T5→D4→C1→T1. Capacitor C1，C3，C4Introduction of C2By-pass, the output voltage of the MMC five-level clamping submodule is Uc1+Uc3+Uc4。
Mode 9: switch tube T1，T4And T5,T8Conduction, T2，T3，T4，T6，T7，T9When the module is cut off, the current flows into the module from the input end of the module in the positive direction, and the current path is D1→C1→D3→C2→D5→C3→D8→C4The current positively flows into the sub-module from the lower input end of the sub-module, and the current path is C4→T8→C3→T5→C2→T3→C1→T1. Capacitor C1，C2，C3，C4The input voltage of the MMC five-level clamping submodule is Uc1+Uc2+Uc3+Uc4。
When the MMC is started or a direct current fault occurs, the insulated gate bipolar transistors enter a locking mode, and current passes through the anti-parallel diode and the diode D of the insulated gate bipolar transistors10And (4) circulating. The MMC five-level clamp submodule works in the following 2 latching modes.
Mode 1: the current flows into the submodule from the input end of the submodule in the positive direction, all the switch tubes are cut off, and the current path is D1→C1→D3→C2→D5→C3→D8→C4Capacitor C1，C2，C3，C4The input voltage of the MMC five-level clamping submodule is Uc1+Uc2+Uc3+Uc4。
Mode 2: the current flows into the submodule from the lower input end of the submodule in the forward direction, all the switch tubes are cut off, and the current path is D10→C1→D3→C2→D2. Capacitor C1，C2The raw materials are put into a mixing tank,C3，C4bypass, MMC five-level clamping submodule output voltage is- (U)c1+Uc2)。
In summary, the operation modes of the MMC five-level clamp submodule topology can be divided into 9 normal switching modes and 2 latching modes, and the device switching states and current paths in each mode are respectively shown in table 1.
Figure BDA0002970120650000051
Table 1: MMC five-level clamping submodule working mode
All IGBT in the locked state, with the current being positive, diode D1，D3，D5，D8On, the capacitance C1，C2，C3，C4Input and output voltage Uc1+Uc2+Uc3+Uc4(ii) a When the current is negative, the diode D10，D3，D2Conducting, sub-module throw-in capacitance C1And C2Output voltage- (U)c1+Uc2)c. The switch tubes in the locked state are all switched off, no matter how the current direction of the bridge arm is, the capacitors are connected in series to be charged, the fault current is rapidly reduced along with the rise of the capacitor voltage in the loop, and finally the fault current is attenuated to zero. Therefore, the converter formed by the MMC five-level clamping submodule has the direct-current fault clearing capacity.
The topological structure of the MMC five-Level clamping submodule with the function of clearing fault current can independently output any capacitor voltage, and the capacitor voltage balance can be realized through a sequencing algorithm under recent Level Modulation (NLM) without adding a closed-loop voltage-sharing controller. According to the current direction of a bridge arm, charging the capacitor and inputting the submodule with a smaller capacitor voltage value, and discharging the capacitor and inputting the submodule with a larger capacitor voltage value; calculating the input capacitance number, dividing by 4, the integer part is N, the remainder is 0, and then sequentially inputting N submodules after sequencing to output 4UcThe cutting output of other modules is 0; the remainder is 1, then the sequence isThen sequentially putting N sub-modules into the reactor to form 4UcN +1 th sub-module throw-in UcThe cutting output of other modules is 0; the remainder is 2, and the N sub-modules are put into 4U after sortingcThe N +1 th sub-module is put into 2UcThe cutting output of other modules is 0; the remainder is 3, and the N sub-modules are put into 4U after sortingcThe N +1 th sub-module is put into 3UcAnd the cutting output of other modules is 0. Therefore, almost all the sub-modules are all the capacitors put in or all the sub-modules are cut off, and the output is 4UcAnd 0, the four capacitors in the submodule have better balance, and each submodule only needs to monitor one capacitor voltage. The number of the voltage values of the capacitors participating in the sequencing is only one fourth of that of the half bridge or the full bridge, so that the hardware investment and the sequencing calculation time are greatly reduced.
The topological structure of the MMC five-level clamping submodule with the function of clearing fault current can be used in the field of flexible direct-current transmission as a multilevel converter, and can also be applied to the field of flexible alternating-current transmission by forming a static synchronous compensator, a unified power quality regulator, a unified power flow controller and other devices to indirectly utilize the topological and thought of the invention in the right scope of other application occasions.
The MMC five-level clamping submodule with the fault current clearing function reversely puts in half of capacitors in a bridge arm through a diode path, and the short-circuit fault current is attenuated to zero by using the unidirectional conductivity of a diode so as to inhibit direct-current fault current, prevent electric arc from being reignited and simultaneously facilitate the quick restart of the MMC.
The invention has the beneficial effects that:
1. the five-level clamping submodule topology can clear direct current fault current without tripping a direct current breaker and an alternating current breaker.
2. The sub-module topology can output unit capacitor voltage of any level based on the recent level modulation NLM strategy; it uses less power electronics with low withstand voltage and reduces the voltage sensors to one fourth of the half-bridge and full-bridge, thereby significantly reducing system hardware costs and controller computation.
3. After the direct current fault, the voltage of the capacitor reaches balance, which is beneficial to the quick restart of the MMC.
4. The invention can clear the direct current fault, protect the MMC to keep the connection state even when the direct current fault has zero impedance, and restart the system quickly.
Drawings
FIG. 1 is a block diagram of a sub-module of the present invention;
FIG. 2 is an overall topology of the present invention;
FIG. 3 is a diagram of a sub-module double-ended MMC simulation model of the present invention;
FIG. 4 is a normal on-mode current loop diagram of a submodule of the present invention;
FIG. 5 is a current loop diagram of a latch-up mode of a submodule of the present invention;
FIG. 6 is a flow chart of NLM modulation of the sub-module of the present invention;
FIG. 7 is a fault-lockout AC current diagram of the present invention;
FIG. 8 is a fault blocking DC current diagram of the present invention;
fig. 9 is a fault-locked dc voltage diagram of the present invention.
Detailed Description
The invention is further described with reference to the following drawings and detailed description.
As shown in fig. 2, the five-level clamping submodule topology structure of the modular multilevel converter MMC comprises an A, B, C three-phase circuit composed of submodules, each phase comprises an upper bridge arm and a lower bridge arm, each bridge arm is composed of N submodules, and two bridge arm reactors are arranged between the upper bridge arm and the lower bridge arm of the A, B, C three-phase circuit. Each bridge arm of the whole MMC topology is provided with N five-level clamping submodules, 9N insulated gate bipolar transistors, 9N +1 diodes and 4N capacitors.
The upper output end of a 1 st sub-module of an upper bridge arm of the A-phase circuit is connected with a direct current bus anode, the lower output end of the 1 st sub-module of the A-phase circuit is connected with the upper output end of a 2 nd sub-module, the upper output end of the 2 nd sub-module is connected with the lower output end of a first sub-module, the lower output end of the 3 rd sub-module is connected with the lower output end of a 3 rd sub-module, the upper output end of the i-th sub-module is connected with the lower output end of an i-1 th sub-module, the lower output end of the i-th sub-module is connected with the upper output end of an i + 1-th sub-module, the upper output end of an Nth sub-module of the upper bridge arm is connected with the lower output;
the upper output end of the 1 st sub-module of the lower bridge arm of the A-phase circuit is connected with the lower bridge arm reactor, the lower output end of the 1 st sub-module of the lower bridge arm is connected with the upper output end of the 2 nd sub-module of the lower bridge arm, the upper output end of the ith sub-module of the lower bridge arm is connected with the lower output end of the (i-1) th sub-module, the lower output end of the ith sub-module of the lower bridge arm is connected with the upper output end of the (i + 1) th sub-module, for the Nth sub-module of the lower bridge arm, the upper output. B. The connection mode of the submodules of the C two-phase circuit is the same as that of the A phase circuit.
As shown in fig. 1, the sub-module comprises an upper sub-module half and a lower sub-module half, both of which are connected by a high power diode D10The voltage negative electrode port of the upper half part of the submodule is connected to the voltage positive electrode port of the lower half part of the submodule, and the voltage negative electrode port of the lower half part of the submodule is connected with the high-power diode D10Is connected with the anode of the first diode half-bridge of the upper half part of the submodule1Voltage anode potential point and high-power diode D10Are connected to each other.
The upper half part of the sub-module comprises a half-bridge sub-module I1 and a half-bridge sub-module II 2 which are connected in a nested manner;
the half-bridge submodule I1 is composed of an insulated gate bipolar transistor T1And its anti-parallel diode D1Insulated gate bipolar transistor T2And its anti-parallel diode D2Capacitor C1Forming;
the half-bridge submodule II 2 is composed of an insulated gate bipolar transistor T3And its anti-parallel diode D3Insulated gate bipolar transistor T4And its anti-parallel diode D4Capacitor C2Forming;
t of half-bridge submodule II 2 module4The collector of the half-bridge submodule I1 is connected with a capacitor C1Negative electrode on the right, T4Emitter and T2Is connected to the negative port of the upper half, T1Emitter and T2The collector electrodes of the half-bridge submodule I1 are connected together to serve as an anode port of the upper half part of the submodule, and a voltage anode port of the half-bridge submodule I1 is a voltage anode output end of a topological structure.
The lower half part of the sub-module comprises a half-bridge sub-module III 3 and a half-bridge sub-module IV 4 which are nested and connected;
the half-bridge submodule III 3 is composed of an insulated gate bipolar transistor T5And its anti-parallel diode D5Insulated gate bipolar transistor T6And its anti-parallel diode D6Insulated gate bipolar transistor T7And its anti-parallel diode D7Capacitor C3Form, an insulated gate bipolar transistor T6And its anti-parallel diode D6Formed switch group and insulated gate bipolar transistor T7And its anti-parallel diode D7The formed switch groups are connected in series in an anti-reverse manner;
the half-bridge sub-module IV 4 is composed of an insulated gate bipolar transistor T8And its anti-parallel diode D8Insulated gate bipolar transistor T9And its anti-parallel diode D9Capacitor C4Forming;
insulated gate bipolar transistor T of half-bridge submodule IV 4 module9The collector of the half-bridge submodule is connected with a capacitor C of the half-bridge submodule III 33Right negative, insulated gate bipolar transistor T9Emitter and insulated gate bipolar transistor T7The emitting electrodes of the two-way bipolar transistor are connected to be used as a negative electrode port of the lower half part of the submodule, and the two-way bipolar transistor T is an insulated gate bipolar transistor5Emitter and insulated gate bipolar transistor T6The collector electrodes of the sub-modules are connected together to serve as an anode port of the lower half part of the sub-module, and a voltage cathode port of the lower half part of the sub-module is a voltage cathode output port of the topological structure.
The upper half part of the submodule consists of four insulated gate bipolar transistors and two capacitors, T1And T2The switch states are opposite; t is3And T4Are in opposite states, respectively controlling two capacitors C1And C2Can output 0, Uc，2UcThree levels. The lower half part of the capacitor is composed of five insulated gate bipolar transistors and two capacitors, T6And T7Are in the same switching state as T5The switch states are opposite; t is8And T9The switch states are opposite, and two capacitors C are respectively controlled3And C4Can output 0, Uc，2UcThree levels. The upper part and the lower part are connected in series and can output 0, Uc，2Uc，3Uc，4UcFive levels. Diode D10The upper and lower circuits are connected with the lower input end of the sub-module and the capacitor C1Between positive stages, secondary mechanism D when submodule is normally switched in10The reverse cutoff is always performed.
As shown in fig. 3, the MMC five-level clamp submodule with the dc fault clearing function can independently output any capacitor voltage, and can realize capacitor voltage equalization by a sorting algorithm under NLM modulation without adding a closed-loop voltage-equalizing controller.
The topological structure of the MMC five-level clamping submodule is controlled by a control switch T1-T9The on-off state of (a) allows the operation mode to be divided into 9 normal modes and 2 latch modes.
As shown in fig. 4, the MMC five-level clamp submodule operates in the following 9 modes. Considering the balanced input of each capacitor in the sub-module, one mode input is selected for each level, and the five level input modes are as follows:
mode 1: switch tube T2，T6，T7Conduction, T1，T3，T4And T5，T8，T9When the module is cut off, the current flows into the module from the input end of the module in the positive direction, and the current path is T2→T6→D7The current positively flows into the submodule from the lower input end of the submodule, and the current path is T7→D6→D2. Capacitor C1，C2，C3，C4All are bypassed, and the MMC five-level clamping submodule cuts off the output voltage to be 0.
Mode 2: switch tube T1，T4And T6，T7Conduction, T2，T3，T5，T8，T9When the module is cut off, the current flows into the module from the input end of the module in the positive direction, and the current path is D1→C1→T4→T6→D7The current positively flows into the submodule from the lower input end of the submodule, and the current path is T7→D6→D4→C1→T1. Capacitor C1Introduction of C2，C3，C4Are all bypassed, and the output voltage of the MMC five-level clamping submodule is Uc1。
Mode 3: switch tube T2And T5，T8Conduction, T1，T3，T4，T6，T7，T9When the module is cut off, the current flows into the module from the input end of the module in the positive direction, and the current path is T2→D5→C3→D8→C4The current positively flows into the sub-module from the lower input end of the sub-module, and the current path is C4→T8→C3→T5→D2. Capacitor C3，C4Introduction of C1，C2By-pass, the output voltage of the MMC five-level clamping submodule is Uc3+Uc4。
Mode 4: switch tube T1，T3And T5，T9Conduction, T2，T4，T6，T7，T8When the module is cut off, the current flows into the module from the input end of the module in the positive direction, and the current path is D1→C1→D3→C2→D5→C3→T9The current positively flows into the submodule from the lower input end of the submodule, and the current path is D9→C3→T5→C2→T3→C1→T1. Capacitor C1，C2，C3Introduction of C4By-pass, the output voltage of the MMC five-level clamping submodule is Uc1+Uc2+Uc3。
Mode 5: switch tube T1，T4And T5，T8Conduction, T2，T3，T4，T6，T7，T9When the module is cut off, the current flows into the module from the input end of the module in the positive direction, and the current path is D1→C1→D3→C2→D5→C3→D8→C4The current positively flows into the sub-module from the lower input end of the sub-module, and the current path is C4→T8→C3→T5→C2→T3→C1→T1. Capacitor C1，C2，C3，C4The input voltage of the MMC five-level clamping submodule is Uc1+Uc2+Uc3+Uc4。
When the MMC is started or a direct current fault occurs, the insulated gate bipolar transistors enter a locking mode, and current passes through the anti-parallel diode and the diode D of the insulated gate bipolar transistors10And (4) circulating. As shown in fig. 5, the MMC five-level clamp submodule operates in the following 2 latch-up modes.
Mode 1: the current flows into the submodule from the input end of the submodule in the positive direction, all the switch tubes are cut off, and the current path is D1→C1→D3→C2→D5→C3→D8→C4Capacitor C1，C2，C3，C4The input voltage of the MMC five-level clamping submodule is Uc1+Uc2+Uc3+Uc4。
2) Mode 2: the current flows into the submodule from the lower input end of the submodule in the forward direction, all the switch tubes are cut off, and the current path is D10→C1→D3→C2→D2. Capacitor C1，C2Introduction of C3，C4Bypass, MMC five-level clamping submodule output voltage is- (U)c1+Uc2)。
Therefore, the switching tubes in the locking state are all turned off, and the capacitors are connected in series to be charged no matter the current direction of the bridge arms. After the system has a direct current short circuit fault, the counter potential provided by the capacitor of the bridge arm cascade module is always in a charging state no matter how the current direction is, and the fault current is rapidly reduced along with the rise of the capacitor voltage in the loop and finally decays to zero. Therefore, the five-level clamping submodule MMC converter has direct-current fault clearing capacity.
The sub-module capacitor is the basis for realizing the AC/DC energy transfer of the MMC, and the condition for keeping the capacitor voltage balance of each sub-module is the necessary condition for stable operation of the MMC. The traditional submodule capacitor voltage sequencing algorithm is large in calculation amount, and the voltage-sharing sequencing algorithm needs to monitor all submodule capacitors.
Any capacitor voltage can be independently output, and the capacitor voltage balance can be realized through a sorting algorithm under the latest level modulation (NLM) without an additional closed-loop voltage-sharing controller. As shown in fig. 6, the specific recent level modulation strategy is:
step 1: and calculating the required input capacitance according to the NLM algorithm.
Step 2: it is determined whether the current direction charges or discharges the capacitor.
Step 3: the monitored voltage value of the capacitor C1 for each submodule is multiplied by the priority coefficient.
Step 4: the capacitor C1 voltage values of the processed sub-modules are sorted.
Step 5: and charging the submodules with smaller voltage, and discharging the submodules with larger voltage.
Step 6: dividing the required input capacitance number by 4, wherein the integer part is N, and the remainder is 0, and then inputting N submodules after sequencing to be all 4 Uc; if the remainder is 1, putting N sub-modules into the sequence to be 4Uc, and putting the (N + 1) th sub-module into the Uc; if the remainder is 2, putting N sub-modules into the sequence to be 4Uc, and putting the (N + 1) th sub-module into the sequence to be 2 Uc; the remainder is 3, then the N sub-modules are put into 4Uc after sorting, and the (N + 1) th sub-module is put into 3 Uc.
Therefore, almost all sub-modules of the MMC five-level clamping sub-module topological structure are all provided with four capacitors or all the capacitors are cut off, and the output is 4UcAnd 0, the four capacitors in the sub-modules have better balance, and each sub-module only needs to be balancedOne capacitor voltage participates in monitoring sequencing, and the quantity of the capacitor voltage values participating in sequencing is only one fourth of that of a half bridge or a full bridge, so that the sequencing calculation time is greatly reduced. Through the priority coefficient processing and the sequencing investment, the voltage-sharing effect of the capacitor can be achieved, the switching frequency is reduced, and the switching loss of a switching device is reduced.
In order to verify that the invention has the fault self-clearing capability and the capacitance voltage balancing effect under the unoccluded condition, a +/-100 kV double-end MMC ultra-high voltage direct current system simulation model with the rated power of 200MW, the voltage of an alternating current power supply of 230kV, the rated voltage of 200kV on a direct current side, the length of a direct current line of 200km, the alternating current frequency of 50Hz and 40 capacitors on a single bridge arm is built in an MATLAB/Simulink simulation platform. And when the bipolar short-circuit permanent fault occurs in the direct-current side line of the smoothing reactor at 1.50s, and all insulated gate bipolar transistors are locked when the fault is detected at 1.502 s. The simulation waveforms are shown in fig. 7-9, and it can be seen from the simulation diagrams that the submodule MMC fault locking mode has a fault current clearing effect, the capacitor voltage balancing effect is also good, the bridge arm current does not exceed 2 times of the rated current, a protection effect is achieved on a power device, and the peak value of alternating current voltage can be raised through the output of the negative level of the submodule.
The foregoing detailed description of the embodiments is presented to enable those skilled in the art to make and use the invention, and is not intended to limit the invention to the particular embodiments described. The basic idea of the invention is to provide a novel submodule structure with direct current fault self-clearing capability in different modes, which is not a commutation system applied to the submodule structure, and any commutation system only needs to use the submodule structure provided by the invention, and the invention falls into the protection scope of the invention. The number of the sub-module structures provided by the invention adopted in the MMC converter system is not limited, the sub-module structures can be completely adopted, and certainly can not be completely adopted, and the sub-module structures and other sub-modules jointly form each bridge arm, so that the invention is within the protection scope of the invention as long as one novel sub-module structure is involved.
Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications to the present invention based on the disclosure of the present invention within the protection scope of the present invention.

Claims (6)

1. The utility model provides a five level of modularization many level transverter MMC presss from both sides submodule topological structure which characterized in that: the bridge arm type three-phase power supply comprises an A, B, C three-phase circuit composed of sub-modules, wherein each phase comprises an upper bridge arm and a lower bridge arm, each bridge arm is composed of N sub-modules, and two bridge arm reactors are arranged between the upper bridge arm and the lower bridge arm of the A, B, C three-phase circuit;
the upper output end of a 1 st sub-module of an upper bridge arm of the A-phase circuit is connected with a direct current bus anode, the lower output end of the 1 st sub-module of the A-phase circuit is connected with the upper output end of a 2 nd sub-module, the upper output end of the 2 nd sub-module is connected with the lower output end of a first sub-module, the lower output end of the 3 rd sub-module is connected with the lower output end of a 3 rd sub-module, the upper output end of the i-th sub-module is connected with the lower output end of an i-1 th sub-module, the lower output end of the i-th sub-module is connected with the upper output end of an i + 1-th sub-module, the upper output end of an Nth sub-module of the upper bridge arm is connected with the lower output;
the upper output end of the 1 st sub-module of the lower bridge arm of the A-phase circuit is connected with a lower bridge arm reactor, the lower output end of the 1 st sub-module of the lower bridge arm is connected with the upper output end of the 2 nd sub-module of the lower bridge arm, the upper output end of the ith sub-module of the lower bridge arm is connected with the lower output end of the (i-1) th sub-module, the lower output end of the ith sub-module of the lower bridge arm is connected with the upper output end of the (i + 1) th sub-module, for the Nth sub-module of the lower bridge arm, the upper output; B. the connection mode of the submodules of the C two-phase circuit is the same as that of the A phase circuit.
2. The modular multilevel converter MMC five-level clamp submodule topology of claim 1, characterized in that: the submodule comprises an upper submodule part and a lower submodule part which are connected through a diode, a voltage negative electrode port of the upper submodule part is connected to a voltage positive electrode port of the lower submodule part, a voltage negative electrode port of the lower submodule part is connected with an anode of the diode, and the upper submodule part is connected with a cathode of the diode.
3. The modular multilevel converter MMC five-level clamp submodule topology of claim 1, characterized in that: the upper half part of the sub-module comprises a half-bridge sub-module I (1) and a half-bridge sub-module II (2) which are connected in a nested manner;
the half-bridge submodule I (1) is composed of an insulated gate bipolar transistor T1And its anti-parallel diode D1Insulated gate bipolar transistor T2And its anti-parallel diode D2Capacitor C1Forming;
the half-bridge submodule II (2) is composed of an insulated gate bipolar transistor T3And its anti-parallel diode D3Insulated gate bipolar transistor T4And its anti-parallel diode D4Capacitor C2Forming;
t of half-bridge submodule II (2) module4The collector of the half-bridge submodule I (1) is connected with a capacitor C1Negative electrode on the right, T4Emitter and T2Is connected to the negative port of the upper half, T1Emitter and T2The collector electrodes of the half-bridge submodule I (1) are connected together to serve as a positive electrode port of the upper half part of the submodule, and a voltage positive electrode port of the half-bridge submodule I is a voltage positive electrode output end of a topological structure.
4. The modular multilevel converter MMC five-level clamp submodule topology of claim 1, characterized in that: the lower half part of the sub-module comprises a half-bridge sub-module III (3) and a half-bridge sub-module IV (4) which are nested and connected;
the half-bridge submodule III (3) is composed of an insulated gate bipolar transistor T5And its anti-parallel diode D5Insulated gate bipolar transistor T6And its anti-parallel diode D6Insulated gate bipolar transistor T7And its anti-parallel diode D7Capacitor C3Form, an insulated gate bipolar transistor T6And its anti-parallel diode D6Is composed ofSwitch group and insulated gate bipolar transistor T7And its anti-parallel diode D7The formed switch groups are connected in series in an anti-reverse manner;
the half-bridge sub-module IV (4) is composed of an insulated gate bipolar transistor T8And its anti-parallel diode D8Insulated gate bipolar transistor T9And its anti-parallel diode D9Capacitor C4Forming;
insulated gate bipolar transistor T of half-bridge submodule IV (4) module9The collector of the half-bridge submodule is connected with a capacitor C of the half-bridge submodule III (3)3Right negative, insulated gate bipolar transistor T9Emitter and insulated gate bipolar transistor T7The emitting electrodes of the two-way bipolar transistor are connected to be used as a negative electrode port of the lower half part of the submodule, and the two-way bipolar transistor T is an insulated gate bipolar transistor5Emitter and insulated gate bipolar transistor T6The collector electrodes of the sub-modules are connected together to serve as an anode port of the lower half part of the sub-module, and a voltage cathode port of the lower half part of the sub-module is a voltage cathode output port of the topological structure.
5. The modular multilevel converter MMC five-level clamp sub-module topology of claim 3, characterized in that: the insulated gate bipolar transistor T1And an insulated gate bipolar transistor T2In opposite switching states, an insulated gate bipolar transistor T3And an insulated gate bipolar transistor T4Are in opposite states, respectively controlling two capacitors C1And C2Can output 0, Uc，2UcThree levels.
6. The modular multilevel converter MMC five-level clamp sub-module topology of claim 4, characterized in that: the insulated gate bipolar transistor T6And an insulated gate bipolar transistor T7Is in the same switching state as the insulated gate bipolar transistor T5In the opposite switching state, the insulated gate bipolar transistor T8And an insulated gate bipolar transistor T8Are in opposite states, respectively controlling two capacitors C3And C4Can output 0, Uc，2UcThree levels.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103904926A (en) * 2014-03-17 2014-07-02 华北电力大学 Improved modular multilevel transverter submodule topology
CN104993683A (en) * 2015-07-15 2015-10-21 南方电网科学研究院有限责任公司 Modular multi-level current converter sub-module circuit
US20150365011A1 (en) * 2013-03-22 2015-12-17 Abb Ab Bipolar double voltage cell and multilevel converter with such a cell
CN107453634A (en) * 2017-08-21 2017-12-08 全球能源互联网研究院 Mixing submodular circuits, bridge arm and MMC topological structures in MMC
US20200201953A1 (en) * 2018-12-19 2020-06-25 Di Shi Generalized Equivalent Circuit Model of MMC-HVDC for Power System Simulation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150365011A1 (en) * 2013-03-22 2015-12-17 Abb Ab Bipolar double voltage cell and multilevel converter with such a cell
CN103904926A (en) * 2014-03-17 2014-07-02 华北电力大学 Improved modular multilevel transverter submodule topology
CN104993683A (en) * 2015-07-15 2015-10-21 南方电网科学研究院有限责任公司 Modular multi-level current converter sub-module circuit
CN107453634A (en) * 2017-08-21 2017-12-08 全球能源互联网研究院 Mixing submodular circuits, bridge arm and MMC topological structures in MMC
US20200201953A1 (en) * 2018-12-19 2020-06-25 Di Shi Generalized Equivalent Circuit Model of MMC-HVDC for Power System Simulation

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
束洪春等: "基于交叉重叠差分变换的MMC-HVDC线路故障识别方法", 《电工技术学报》, vol. 36, no. 1, pages 203 - 214 *

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