CN110739871B - Alternating current charging control strategy suitable for hybrid MMC under two working conditions of short circuit and no short circuit on direct current side - Google Patents

Alternating current charging control strategy suitable for hybrid MMC under two working conditions of short circuit and no short circuit on direct current side Download PDF

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CN110739871B
CN110739871B CN201910899694.XA CN201910899694A CN110739871B CN 110739871 B CN110739871 B CN 110739871B CN 201910899694 A CN201910899694 A CN 201910899694A CN 110739871 B CN110739871 B CN 110739871B
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bridge
full
switching tube
diode
submodule
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CN110739871A (en
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郑星星
徐攀腾
宋述波
包威
李金安
杨学广
周登波
朱博
李建勋
严海健
焦石
李倩
顾硕铭
郭云汉
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Guangzhou Bureau of Extra High Voltage Power Transmission Co
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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
    • H02M7/02—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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • 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
    • H02M1/36—Means for starting or stopping converters
    • 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
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Abstract

The invention discloses an alternating current charging control strategy suitable for a hybrid MMC under two working conditions of short circuit and no short circuit on a direct current side, which comprises the following steps: switching on the alternating current breaker, and uncontrollably charging the full-half bridge sub-module and the half-bridge sub-module; after the full-bridge submodule enters a controllable state and the average voltage of the full-bridge submodule is greater than a certain value, all full-bridge submodule T2 switching tubes are conducted; when the average voltage of the full and half-bridge submodules reaches a set value, a submodule voltage-sharing control strategy is put into, the full and half-bridge submodules are uniformly sorted, a certain number of the full and half-bridge submodules are gradually cut off, the full and half-bridge submodules are charged to be close to a rated value, and the charging start is completed. According to the charging control strategy, the MMC control system does not need to additionally judge the MMC operation mode, the MMC access state does not need to be judged, the controller program design can be simplified, and the reliability of successful charging starting of the hybrid MMC is improved.

Description

Alternating current charging control strategy suitable for hybrid MMC under two working conditions of short circuit and no short circuit on direct current side
Technical Field
The invention relates to a flexible direct current transmission technology, in particular to an alternating current charging control strategy suitable for a hybrid MMC under two working conditions of short circuit and no short circuit on a direct current side.
Background
Compared with the conventional direct current transmission technology, the flexible direct current transmission technology has the advantages of no need of reactive compensation, no problem of phase commutation failure, convenient active and reactive power regulation, low harmonic level, suitability for forming a multi-terminal direct current system and the like, so that the flexible direct current transmission related technology is rapidly developed, wherein the flexible direct current transmission system based on an MMC (modular multilevel converter) topological structure has the most representative and technical advantages. The mixed MMC has the outstanding advantages of direct-current side fault clearing capacity, voltage reduction operation capacity, relatively low cost and loss and the like, has wide application prospect in the field of flexible direct-current transmission, and is very suitable for the topological structure of the ultrahigh-voltage flexible direct-current transmission converter valve group unit. At present, an extra-high voltage flexible direct current transmission system based on two mixed MMC valve sets connected in series mainly faces two problems in the aspect of alternating current charging starting:
(1) AC charging, the inconsistent problem of full, half-bridge submodule charge rate under the condition of the short circuit not of group valve direct current side:
the hybrid MMC is composed of three symmetrical phase units, each phase unit is divided into an upper bridge arm and a lower bridge arm, the bridge arms are completely symmetrical, each bridge arm is composed of N sub-modules (containing x half-bridge sub-modules and y full-bridge sub-modules) in cascade connection and a series reactor, the topological structure diagram of each bridge arm is shown in figure 1, and the current marked in figure 1 is a specified positive direction.
Under the locking state of all switching tubes (the controllable power devices numbered as T1, T2, T3, T4, T5 and T6 in fig. 1) of the submodules, the charging conditions of the full-bridge and half-bridge submodules in different bridge arm current directions are as shown in fig. 2.
At the initial stage after the alternating current circuit breaker is switched on, the energy-taking power supply of the submodule is not powered, all switch tubes are in a turn-off state, and current can only flow through the anti-parallel diodes of the switch tubes, and the stage is called an uncontrollable charging stage. The half-bridge sub-module can be charged only when the bridge arm current is in a positive direction, and the half-bridge sub-module is in a bypass state and cannot be charged when the bridge arm current is in a negative direction; the full-bridge submodule can charge the capacitor under the condition of positive or negative bridge arm current.
An equivalent circuit diagram of the hybrid MMC under the ac side closing charging can be drawn by combining fig. 1 and fig. 2 as shown in fig. 3. Under the uncontrollable charging state, the direction of bridge arm current depends on the three-phase voltage U at the MMC alternating side at the current momentva、Uvb、UvcMagnitude of instantaneous value: for a phase with the highest phase voltage, the upper bridge arm of the phase flows through negative current, and the lower bridge arm of the phase flows through positive current; for the phase with the lowest phase voltage, the upper bridge arm of the phase flows through positive current, and the lower bridge arm of the phase flows through negative current. The MMC alternating-current side three-phase voltage is a regular three-phase sine wave with the phase difference of 120 degrees and is 0-axis symmetry, the bridge arm current also changes periodically along with the MMC alternating-current side voltage in positive and negative half cycles, the charging opportunities of 6 bridge arms are equal, but the full-bridge submodule can be charged in the positive and negative half cycles of the bridge arm current, and the half-bridge submodule can be charged only in the positive half cycle, so that the charging rate of the full-bridge submodule is far higher than that of the half-bridge submodule, and the serious voltage unbalance between the full-bridge submodule and the half-bridge submodule is caused.
In order to solve the above problem, chinese patent application publication No. CN106787087A discloses a start-up charging method, in which a T4 switch tube for turning on the full-bridge submodule is triggered immediately after the full-bridge submodule is charged to an energy-obtaining power supply to work, and a schematic diagram is shown in fig. 4. After the T4 switch tube is switched on, the full-bridge submodule is not charged by the bypass under the condition that the bridge arm current is negative, so that the full-bridge submodule is forced to be charged only in the positive half cycle of the bridge arm current, and the difference between the voltages of the full-bridge submodule and the half-bridge submodule in the charging process is reduced. However, the method can only solve the problem of inconsistent alternating current charging rates of the full-bridge submodule and the half-bridge submodule under the condition that the direct current side of the valve group is not short-circuited.
(2) AC charging, the half-bridge submodule can not get the electric work problem under the short circuit condition of the direct current side of the valve group:
compared with a conventional high-voltage flexible single-valve-group direct-current power transmission system, the extra-high-voltage flexible series-connection two-valve-group direct-current power transmission system also needs to meet a basic requirement: the valve group is put into on-line, that is, the flexible converter valve group is required to have the charge starting and unlocking operation capability under the condition of direct-current side short circuit besides the charge starting and unlocking operation capability of the conventional flexible valve group. Exchange side U with MMCvaHighest, UvbThe lowest example (i.e., the a-phase upper bridge arm current is negative, the lower bridge arm current is positive, and the b-phase upper bridge arm current is positive, and the lower bridge arm current is negative) illustrates the sub-module charging situation under the condition of short circuit at the direct current side, and the schematic diagram of the equivalent circuit is shown in fig. 5.
In the initial charging stage, the upper and lower bridge arms of phase a are charged, the current of the upper bridge arm is negative, only the full-bridge submodule is charged, the current of the lower bridge arm is positive, the full-bridge submodule and the half-bridge submodule are charged, as the charging is carried out, the direct current voltage of the lower bridge arm (the voltage of the full-bridge submodule + the voltage of the half-bridge submodule) is higher than that of the upper bridge arm (the voltage of the full-bridge submodule only), and the diode of the lower bridge arm is turned off; the upper bridge arm and the lower bridge arm of the phase b are the same, so that only the full-bridge submodule is charged, and the half-bridge submodule cannot be charged and started normally.
Aiming at the problem, a research content of a hybrid MMC starting charging strategy [ J ] in the process of putting an extra-high voltage flexible direct-current valve bank into operation and power system automation 2018 and 42(24) discloses a starting method, wherein a part of a full-bridge submodule in a bridge arm is cut off by measuring the current of the bridge arm of the MMC and the instantaneous voltage value of a three-phase valve side when the current of the bridge arm is positive, so that the current of the bridge arm is forced to flow through the bridge arm containing the half-bridge submodule to charge the half-bridge submodule, but the method is only suitable for the charging starting of the hybrid MMC under the condition that the direct-current side of the alternating-current valve bank.
In summary, the current ac charging method for the hybrid MMC can only be effective under specific operating conditions, and two or more methods must be combined to realize normal charging start of the hybrid MMC under two conditions of short circuit and no short circuit on the dc side, meanwhile, the implementation of the methods needs to depend on a control system to judge the wiring mode (direct current side short circuit starting or direct current side non-short circuit starting) of the current valve group in advance, and select different charging starting control strategies according to the current operation mode, therefore, a control system is required to access a switch position signal (such as a valve bank bypass switch position signal and the like) for judging the state of the MMC, program valve bank state judgment logic and charging mode selection logic are designed, complexity and design difficulty of a control program are increased, and risk of failure of MMC charging starting caused by misjudgment of a charging starting mode exists.
Disclosure of Invention
In view of the above reasons, the invention provides an alternating current charging control strategy suitable for a hybrid MMC under two working conditions of short circuit and no short circuit on a direct current side, which is used for charging the hybrid MMC under two working conditions of short circuit and no short circuit on the direct current side without judging the access state of the MMC, can simplify the program design of a controller, reduce the access of external switch position signals to the controller, and improve the reliability of successful charging start of the hybrid MMC.
In order to realize the purpose, the invention adopts the technical scheme that:
the utility model provides an alternating current charging control strategy that is adapted to mixed MMC under two kinds of operating modes of direct current side short circuit and no short circuit, includes:
switching on the alternating current breaker, and uncontrollably charging the full-half bridge sub-module and the half-bridge sub-module;
after the full-bridge submodule enters a controllable state and the average voltage of the full-bridge submodule is larger than a certain value, all full-bridge submodule T2 switching tubes are conducted, and the full-bridge submodule degenerates to be charged only in a period when the current of a bridge arm is negative;
when the average voltage of the full and half-bridge submodules reaches a set value, a submodule voltage-sharing control strategy is put into, the full and half-bridge submodules are uniformly sorted, a certain number of the full and half-bridge submodules are gradually cut off, the full and half-bridge submodules are charged to be close to a rated value, and the charging start is completed.
Furthermore, the set value is 0.6Ucn, the approximate rated value is 0.95-1 Ucn, and Ucn is the rated voltage of the full and half-bridge submodule capacitors.
Compared with the prior art, the invention has the beneficial effects that:
the charging control strategy of the invention does not need an MMC control system to additionally judge the MMC operation mode and judge the MMC access state, can simplify the program design of the controller, reduce the access of an external switch position signal to the controller, eliminate the risk of failure of MMC charging start caused by misjudgment of the charging start mode due to the reasons of error, disappearance, jitter and the like of an external switch position signal, and improve the reliability of successful charging start of the mixed type MMC.
Drawings
FIG. 1 is a schematic diagram of a hybrid MMC topology and full and half bridge sub-modules;
FIG. 2 is a schematic diagram of charging full-bridge and half-bridge sub-modules in different bridge arm current directions; (ii) a
FIG. 3 is an equivalent circuit diagram of AC charging without short circuit on the DC side of the hybrid MMC;
FIG. 4 is a schematic diagram of a prior art path where bridge arm current is negative after a T4 switching tube is triggered;
FIG. 5 is an equivalent circuit diagram of AC charging under the condition of short circuit on the DC side of the hybrid MMC;
FIG. 6 is a schematic diagram illustrating a charging process of the charging control strategy according to the present invention;
FIG. 7 is a schematic diagram illustrating the variation of the number of sub-modules in the controllable charging phase according to the present invention;
FIG. 8 is a schematic diagram of the current path after full bridge submodule T2 of the present invention is turned on;
FIG. 9 is a schematic diagram of a charging path of the full-bridge submodule T2 according to the present invention that is not shorted at the DC side after being turned on;
fig. 10 is a schematic diagram of the dc-side short-circuited charging path after the full-bridge sub-module T2 is turned on.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
As shown in fig. 6 and 7, an ac charging control strategy adapted to a hybrid MMC under two working conditions of short circuit and no short circuit on a dc side of the hybrid MMC includes:
(1) after the MMC control system receives a charging instruction, the full-bridge submodule and the half-bridge submodule are subjected to uncontrollable charging (the full-bridge charging speed is high, and the voltage is about 2 times of that of the half-bridge) after the alternating-current circuit breaker is switched on;
(2) the full-bridge submodule is firstly charged to the minimum working voltage, the full-bridge submodule is communicated with the MMC control system to enter a controllable state (the half-bridge submodule is still not charged to the minimum working voltage and is in the uncontrollable state at the moment), and when the average voltage of the full-bridge submodule is larger than a certain value Uy1After the system parameters are set, the MMC control system issues switching-on trigger signals of all full-bridge submodule T2 switching tubes, and controls all full-bridge submodule T2 switching tubes in six bridge arms to be in a switching-on state;
(3) along with the charging, the half-bridge sub-module is also charged to the minimum working voltage and establishes communication with the MMC control system to enter a controllable state; when the average voltage of the full and half-bridge sub-modules reaches 0.6Ucn or the setting is calculated according to the actual condition of the system (Ucn is the rated voltage of the capacitors of the full and half-bridge sub-modules), putting in a sub-module voltage-sharing control strategy, uniformly sequencing the full and half-bridge sub-modules, and putting in a fixed number N in the initial stagekRapidly balancing the voltage among the submodules with lower voltage, then reducing the input number of the submodules according to a certain slope, gradually controlling the average voltage value of the submodules to be 0.90-1 Ucn, and finally fixing the number Ns(the fixed number can be calculated according to the condition of the MMC system, the average voltage of the submodule after controllable charging is ensured to be 0.90-1 Ucn), the charging starting is completed, and an MMC unlocking operation signal is waited.
The principle that the charging control strategy of the present invention can be applied to the ac charging of the hybrid MMC under the conditions of short circuit and no short circuit on the dc side is explained as follows:
principle analysis suitable for condition that direct current side is not short-circuited
After the full-bridge submodule is charged to the minimum working voltage and enters a controllable state, the T2 switching tube is triggered, and the current flowing condition in the positive and negative periods of the bridge arm current is shown in fig. 8. As can be seen from fig. 8, when the switching tube of the full-bridge submodule T2 is turned on, the full-bridge submodule degenerates to be charged only in the period where the bridge arm current is negative, and as can be seen from the MMC operating characteristics, the bridge arm current is a regular sine wave that varies periodically and is axisymmetric 0 in the charging state, that is, the charging effect of the positive and negative half cycles is the same. Therefore, after the switch tube of the full-bridge submodule T2 is switched on, the charging opportunities of the full-bridge submodule and the half-bridge submodule are equal, and the problem of inconsistent charging rates of the full-bridge submodule and the half-bridge submodule under the condition that a direct current side is not short-circuited is effectively solved.
And (3) under the condition that the direct current side is not short-circuited, analyzing the charging effect after the full-bridge submodule T2 is switched on: still taking the example that the phase voltage a is the highest and the phase b is the lowest, the MMC equivalent circuit diagram is shown in fig. 9, the current flows through the upper and lower bridge arms of the phases a and b at the same time, wherein one current flows through all the full-bridge sub-modules of the upper bridge arm of the phase a + all the half-bridge sub-modules of the upper bridge arm of the phase b; and the other path of current flows through all half-bridge sub-modules of the phase a lower bridge arm and all full-bridge sub-modules of the phase b lower bridge arm, the current path parameters are completely the same, the natural charging current balance characteristic is realized, and the charging rates of the full-bridge sub-modules and the half-bridge sub-modules are completely consistent. And when the average voltage of the full and half-bridge sub-modules reaches 0.6Ucn, a voltage-sharing strategy can be put into use, the voltages of the full and half-bridge sub-modules are uniformly charged to be close to rated values, the charging start is completed, and an MMC unlocking operation signal is waited.
Principle analysis suitable for direct current side short circuit condition
Similarly, after the alternating current circuit breaker is switched on, all the full-bridge submodules are charged to the minimum working voltage firstly, and after the full-bridge submodules enter a controllable state, the T2 switching tube is triggered. As can be seen from the foregoing analysis and by referring to fig. 8, the full-bridge sub-modules with positive bridge arm currents are all in the cut-off state, and can be charged only when the bridge arm currents are negative, and the equivalent schematic diagram is shown in fig. 10, which still takes the example that the a-phase voltage is the highest and the b-phase is the lowest.
As can be seen from fig. 10, at this time, all full-bridge sub-modules (the number is y) of the phase a upper bridge arm are charged, all half-bridge sub-modules (the number is x) of the phase b lower bridge arm are charged, and y is required to be greater than x in order to fully exert the advantages of the hybrid MMC in the engineering, so that the direct current voltage (the sum of all the full-bridge sub-module voltages) of the phase a upper bridge arm is higher than that of the phase b lower bridge arm (only the half-bridge sub-module voltage), and the diodes of; b, the upper bridge arm and the lower bridge arm are the same, so that charging current can be forced to flow through the half-bridge submodule to charge the half-bridge submodule, the half-bridge submodule is also charged to the minimum working voltage along with the charging, communication is established between the half-bridge submodule and the MMC control system, after the half-bridge submodule enters a controllable state, a voltage-sharing strategy can be put into when the average voltage of the full-bridge submodule and the half-bridge submodule reaches 0.6Ucn, the voltage of the full-bridge submodule and the half-bridge submodule is uniformly charged to be close to a rated value, the charging starting is completed.
Therefore, the charging control strategy of the invention does not need an MMC control system to additionally judge the MMC operation mode and judge the MMC access state, can simplify the program design of the controller, reduces the access of external switch position signals to the controller, eliminates the risk of failure of MMC charging start caused by misjudgment of the charging start mode due to the reasons of external switch position signal error, disappearance, jitter and the like, and improves the reliability of the success of hybrid MMC charging start.
The above detailed description is specific to possible embodiments of the present invention, and the embodiments are not intended to limit the scope of the present invention, and all equivalent implementations or modifications that do not depart from the scope of the present invention are intended to be included within the scope of the present invention.

Claims (2)

1. An alternating current charging control strategy suitable for a hybrid MMC under two working conditions of short circuit and no short circuit on a direct current side is provided, the hybrid MMC comprises three phase units, each phase unit comprises an upper bridge arm and a lower bridge arm which are identical in structure, each bridge arm comprises y full-bridge submodules, x half-bridge submodules and a bridge arm reactor, and the number y of the full-bridge submodules is greater than the number x of the half-bridge submodules;
the half-bridge submodule comprises a switching tube T5, a switching tube T6, a capacitor C1 and a voltage-sharing resistor R1; the capacitor C1 is connected with the voltage-sharing resistor R1 in parallel; an emitter of the switching tube T5 is connected with a collector of the switching tube T6, a collector of the switching tube T5 is connected with the anode of the capacitor C1, and an emitter of the switching tube T6 is connected with the cathode of the capacitor C1; a diode D5 is reversely connected in parallel with the switching tube T5, the cathode of the diode D5 is connected with the collector of the switching tube T5, and the anode of the diode D5 is connected with the emitter of the switching tube T5; a diode D6 is reversely connected in parallel with the switching tube T6, the anode of the diode D6 is connected with the emitter of the switching tube T6, and the cathode of the diode D6 is connected with the collector of the switching tube T6; the two ends of the switching tube T6 are the output of the half-bridge submodule;
the full-bridge submodule comprises a switching tube T1, a switching tube T2, a switching tube T3, a switching tube T4, a capacitor C and a voltage-sharing resistor R; the capacitor C is connected with the voltage-sharing resistor R in parallel; an emitter of the switch tube T1 is connected with a collector of the switch tube T2, an emitter of the switch tube T3 is connected with a collector of the switch tube T4, a collector of the switch tube T1 and a collector of the switch tube T3 are both connected with the positive electrode of the capacitor C, and an emitter of the switch tube T2 and an emitter of the switch tube T4 are both connected with the negative electrode of the capacitor C; the switching tube T1 and the switching tube T2 form a first half-bridge structure, and the switching tube T3 and the switching tube T4 form a second half-bridge structure; a diode D1 is reversely connected in parallel with the switching tube T1, the cathode of the diode D1 is connected with the collector of the switching tube T1, and the anode of the diode D1 is connected with the emitter of the switching tube T1; a diode D2 is reversely connected in parallel with the switching tube T2, the anode of the diode D2 is connected with the emitter of the switching tube T2, and the cathode of the diode D2 is connected with the collector of the switching tube T2; a diode D3 is reversely connected in parallel with the switching tube T3, the cathode of the diode D3 is connected with the collector of the switching tube T3, and the anode of the diode D3 is connected with the emitter of the switching tube T3; a diode D4 is reversely connected in parallel with the switching tube T4, the anode of the diode D4 is connected with the emitter of the switching tube T4, and the cathode of the diode D4 is connected with the collector of the switching tube T4; the middle point of the two half-bridge structures is the output of the full-bridge submodule; the method is characterized in that: the alternating current charging control strategy comprises the following steps:
switching on the alternating current breaker, and uncontrollably charging the full-half bridge sub-module and the half-bridge sub-module;
after the full-bridge submodule enters a controllable state and the average voltage of the full-bridge submodule is larger than a certain value, all full-bridge submodule T2 switching tubes are conducted, and the full-bridge submodule degenerates to be charged only in a period when the current of a bridge arm is negative;
when the average voltage of the full-half-bridge sub-modules and the half-bridge sub-modules reaches a set value, putting in a sub-module voltage-sharing control strategy, uniformly sequencing the full-half-bridge sub-modules and the half-bridge sub-modules, gradually cutting off a certain number of the full-half-bridge sub-modules and the half-bridge sub-modules, charging the voltages of the full-half-bridge sub-modules and the half-bridge sub;
the set value is 0.6Ucn, and Ucn is the rated voltage of the full and half-bridge submodule capacitors.
2. The AC charging control strategy adapted to the hybrid MMC under two working conditions of short circuit and no short circuit on the DC side of the hybrid MMC according to claim 1, is characterized in that: the approximate rated value is 0.95-1 Ucn.
CN201910899694.XA 2019-09-23 2019-09-23 Alternating current charging control strategy suitable for hybrid MMC under two working conditions of short circuit and no short circuit on direct current side Active CN110739871B (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105119508A (en) * 2015-09-18 2015-12-02 山东建筑大学 Modularized multi-level current converter with hybrid-cascaded full-bridge and half-bridge sub-modules and starting method thereof
CN107317472A (en) * 2017-06-30 2017-11-03 中国西电电气股份有限公司 A kind of full-bridge starts method with half-bridge mixed type module multilevel converter
CN107947618A (en) * 2017-12-12 2018-04-20 荣信汇科电气技术有限责任公司 Converter valve alternating current side controllable charging method based on full-half-bridge mixed connection topology

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105119508A (en) * 2015-09-18 2015-12-02 山东建筑大学 Modularized multi-level current converter with hybrid-cascaded full-bridge and half-bridge sub-modules and starting method thereof
CN107317472A (en) * 2017-06-30 2017-11-03 中国西电电气股份有限公司 A kind of full-bridge starts method with half-bridge mixed type module multilevel converter
CN107947618A (en) * 2017-12-12 2018-04-20 荣信汇科电气技术有限责任公司 Converter valve alternating current side controllable charging method based on full-half-bridge mixed connection topology

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