CN108809132A - Hybrid MMC half-bridges submodule capacitor voltage balance method - Google Patents
Hybrid MMC half-bridges submodule capacitor voltage balance method Download PDFInfo
- Publication number
- CN108809132A CN108809132A CN201810668992.3A CN201810668992A CN108809132A CN 108809132 A CN108809132 A CN 108809132A CN 201810668992 A CN201810668992 A CN 201810668992A CN 108809132 A CN108809132 A CN 108809132A
- Authority
- CN
- China
- Prior art keywords
- bridge
- bridge arm
- capacitor voltage
- current
- voltage balance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/483—Converters with outputs that each can have more than two voltages levels
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/483—Converters with outputs that each can have more than two voltages levels
- H02M7/4835—Converters with outputs that each can have more than two voltages levels comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Supply And Distribution Of Alternating Current (AREA)
- Rectifiers (AREA)
- Inverter Devices (AREA)
Abstract
The invention discloses hybrid MMC half-bridges submodule capacitor voltage balance methods, current conversion station is by full-bridge submodule (Full Bridge Sub Modular,) and half-bridge submodule (Half Bridge Sub Modular FBSM, HBSM it) mixes, when FBSM accountings are relatively low and the operation of straight-flow system voltage is relatively low, improve the direct current biasing of bridge arm current by the method for side reactive power of increasing exchanges, make bridge arm current have just have it is negative, the charge and discharge probability for increasing HBSM, keeps its capacitor voltage balance controllable.
Description
Technical field
The invention belongs to technical field of direct current power transmission, and in particular to hybrid MMC half-bridges submodule capacitor voltage balance side
Method.
Background technology
It is to realize the optimization of China's energy resources, prevent the objective of commutation failure from wanting that MMC, which is applied to the transmission of electricity of large capacity overhead line,
Ask, in conjunction with both LCC and VSC advantage, converting plant uses LCC, Inverter Station using VSC mixed type HVDC transmission system at
For the hot spot of academic research.Since large capacity long distance power transmission is frequently with overhead transmission line, exposed circuit is easy to happen short circuit, dodges
The temporary faults such as network.However currently based on the MMC of half-bridge submodule (half bridge sub-module, HBSM) without the image of Buddha
LCC completes merely the removing of DC side failure by converter Control like that, even if locking transverter, AC system still can be through
The inverse parallel fly-wheel diode of device and DC Line Fault point constitute energy flow circuit in inverter inside two-phase bridge arm, thus
It is not suitable for being applied to overhead line occasion.MMC based on full-bridge submodule (full bridge sub-module, FBSM) can toning
System runs and DC operating voltage is greatly reduced, therefore especially noticeable.But with the half-bridge MMC of identical capacity and voltage class
It compares, the power electronic devices that full-bridge MMC is used is almost double, not only increases cost of investment, but also introduces more operations
Loss.Therefore the transverter topological structure that MMC current conversion stations are mixed using half-bridge and full-bridge submodule, in detail as shown in Figure 1.It is main
Application scenario：The electric power of Energy Base is extensive, sends outside at a distance, is generally sent to thousands of public affairs via extra high voltage direct current transmission line
Load center inside and outside.How to optimize hybrid MMC, reduces the use of FBSMs to the greatest extent under conditions of meeting system performance.It is mixed
The submodule of box-like MMC about 50% is necessary for full-bridge submodule.Under this condition, if temporary fault occurs for straight-flow system,
In the crossing process of DC Line Fault, HBSM has been not involved in capacitor voltage balance control, such feelings due to the biasing of bridge arm current
It is run after being unfavorable for the fault recovery of system under condition.
Invention content
To solve the above-mentioned problems, the present invention provides hybrid MMC half-bridges submodule capacitor voltage balance methods, improve
Hybrid MMC half-bridges submodule capacitor voltage balance, ensures the capacitor voltage balance of HBSM when straight-flow system subnormal voltage operation.
In order to achieve the above objectives, hybrid MMC half-bridges submodule capacitor voltage balance method of the present invention, it is hybrid
MMC includes ABC three-phases, per being mutually divided into bridge arm and lower bridge arm, each bridge arm by the identical half-bridge submodule of several structures and
Full-bridge sub-module cascade and with a bridge arm inductance L0It is connected in series, a phase element is constituted with mutually upper and lower two bridge arms；Pass through
Increasing the reactive power of transverter exchange side improves the direct current biasing of bridge arm current, make bridge arm current have just have it is negative.
Further, by increasing the reactive power of transverter exchange side, to increase transverter ac output end phase current
Amplitude Im, make ImMeet relational expressionWherein IdcFor DC current.
Further, in the crossing process of DC Line Fault, the detection of bridge arm current direct current biasing is enabled, when bridge arm current is
When complete bias state, the reactive power for starting exchange side increases mechanism, in the power bracket that MMC transverters allow, continues
Increase the definite value Q of reactive powerref, until complete bias state disappears.
Further, after the completion of DC Line Fault passes through, system then exits reactive power and increases mechanism when restoring normal,
QrefRevert to the definite value before DC Line Fault.
Further, in hybrid MMC, full-bridge submodule accounting is 45%-55%.
Compared with prior art, the present invention at least has technique effect beneficial below, when the FBSM in hybrid MMC is accounted for
When relatively low (about 50%) and straight-flow system working voltage relatively low (about 0.5pu), increase the method for reactive power by exchange side
Improve the direct current biasing of bridge arm current, so that bridge arm current is had just has negative, increases the charge and discharge probability of HBSM, makes its capacitance voltage
Balance is controllable.In the case where not increasing FBSM accountings, only by increasing the electricity that HBSM can be realized in reactive power in exchange side
Hold the balance of voltage.The HBSM ameliorative ways are specially adapted to the lower occasion of FBSM accountings, can reduce the primary of straight-flow system
Cost, economy are good.The method only DC Line Fault pass through or the damage of subnormal voltage operation under effectively, do not increase and be
The cost of system.
Description of the drawings
Fig. 1 is hybrid MMC transverters detailed topologies schematic diagram；
Fig. 2 is MMC line charts；
Fig. 3 is HBSM submodules bulk state and current path schematic diagram；
Fig. 4 is to increase reactive power schematic diagram.
Specific implementation mode
The following describes the present invention in detail with reference to the accompanying drawings and specific embodiments.
Referring to Fig.1, the Basic Topological of hybrid MMC is as shown in Figure 1, it is made of 6 bridge arms of three-phase, each bridge arm
By several structures identical HBSM and FBSM cascade and with a bridge arm inductance L0It is connected in series, with mutually upper and lower two bridge arms
Constitute a phase element.HBSM submodules as shown in figure 3, HBSM submodules output voltage there are two kinds of possibility：When above
IGBT T1 conductings, IGBT T2 below have when turning off, Usm=Uc；When IGBT T1 shutdowns above, IGBT T2 below are led
Have when logical, Usm=0.
With reference to Fig. 2, since each HBSM of MMC are a full control half-bridges, according to the switch of 2 IGBT in each submodule
SM submodules can be divided into three kinds of locking, input and excision operating statuses, in detail as shown in Figure 2 by state：
Operating status one：IGBT T1 and IGBT T2 are turned off：This state is the blocking of transverter, generally in failure
It is used when the charging initial stage that period or transverter start.When normal power transmits, which will not occur.
Operating status two：IGBT T1 conductings, IGBT T2 shutdowns：Regardless of the direction of bridge arm current, submodule port
Voltage is equal to submodule capacitance voltage in the block.Bridge arm current direction determinant module capacitance is in charging or discharge condition,
This state is known as input state.
Operating status two：IGBT T1 shutdowns, IGBT T2 conductings：Regardless of the direction of bridge arm current, the end of submodule
Mouth voltage is equal to 0, and capacitance is bypassed in submodule, and capacitance voltage keeps stablizing, this state is excision state.
Referring to Fig.1, according to related research, the accounting demand of FBSM can be using tabular form as following formula：
M in above formulaacFor AC modulation degree.From the constraint of customary DC, minimum operation electricity when because of its brownout operation
Pressure is 0.7 times of rated direct voltage, and the submodule that can obtain about 50% is necessary for full-bridge submodule.Full-bridge submodule and half-bridge submodule
Depending on the composition of block is according to actual demands of engineering, project cost is generally reduced, the ratio of FBSM should be as low as possible.At this
Under the conditions of, if straight-flow system occur temporary fault, as DC Line Fault crossing process in, HBSM is due to bridge arm current
Biasing does not participate in capacitor voltage balance control, is run after being unfavorable for the fault recovery of system in such cases.
If the expression formula of AC phase currents：
iva=Imcos(ωt+θia) (1)
In above formula：Im is the amplitude of transverter ac output end phase current；θiaFor the initial angle values of phase current.
By taking bridge arm current in a phases as an example, ignore circulation influence, the expression formula of bridge arm current is as shown in Figure 1：
For HBSMs, the charging and discharging needs of submodule capacitance carry out under the bridge arm current of different directions.?
I.e. HBSMs capacitance voltages keep balance necessary condition be bridge arm current must existing positive value also have negative value.And FBSMs can be
Charge or discharge are carried out under same bridge arm current direction, so without this requirement.Therefore it is holding capacitor electricity for HBSMs
Flatten weighing apparatus, it is necessary to introduce following constraints：
In above formula, IdcRefer to DC current.The present invention increases I by the reactive power for side of increasing exchangesmValue, make
Value be more than DC current 1/3 bridge arm current can be made negative value occur, in the case where not increasing FBSM accountings, pass through change
The capacitor voltage balance of HBSM can be realized in the reactive power of exchange side.
When carrying out DC Line Fault and passing through, the reactive power for starting exchange side increases mechanism, and DC Line Fault such as passes through at the transient state
Operating mode terminates, and system power voltage exits reactive power and increases mechanism when restoring normal.It is specific as shown in Figure 4：
At present for voltage-source type DC transmission system, common control method is Direct Current Control, as shown above
iq_refReactive current reference value after being decoupled for dq.During passing through equal transient operating modes, bridge arm current is enabled in DC Line Fault
The complete bias detection of direct current, as long as bridge arm current is complete bias state, then in the power bracket that MMC transverters allow, one
The straight definite value Q for increasing reactive powerref, until complete bias state disappears, i.e. the existing positive value of bridge arm current also has negative value
It has been completed when DC Line Fault passes through, system then exits reactive power and increases mechanism, Q when restoring normalrefIt reverts to
Definite value before DC Line Fault.
By formula (3) it is found that after the amplitude increase of alternating voltage, since bridge arm current is 1/2 AC phase currents and 1/3
The superposition of DC current so that its existing positive value is also had so electric current of increasing exchanges can improve the direct current biasing of bridge arm current
Its capacitance voltage can be better balanced in negative value, such HBSM.The method should avoid long-play as possible, to reduce to exchange
The reactive power impact of system influences.
The present invention is write program, is debugged and test by electromagnetic transient in power system profession emulation tool PSCAD/EMTDC
Card.This strategy is suitble to the HBSM capacitor voltage balances of the hybrid MMC of receiving end of LCC+MMC mixed DCs, control strategy simple
It is easy-to-use, the capacitance voltage of HBSM can be balanced in transient process, and there is great engineering practical value.
Claims (6)
1. hybrid MMC half-bridges submodule capacitor voltage balance method, which is characterized in that hybrid MMC includes ABC three-phases, often
Mutually be divided into bridge arm and lower bridge arm, each bridge arm by the identical half-bridge submodule of several structures and full-bridge sub-module cascade and with
One bridge arm inductance L0It is connected in series, a phase element is constituted with mutually upper and lower two bridge arms；By increasing transverter exchange side
Reactive power improves the direct current biasing of bridge arm current, make bridge arm current have just have it is negative.
2. hybrid MMC half-bridges submodule capacitor voltage balance method according to claim 1, which is characterized in that pass through
The reactive power for increasing transverter exchange side, to increase the amplitude I of transverter ac output end phase currentm, make ImMeet relational expressionWherein IdcFor DC current.
3. hybrid MMC half-bridges submodule capacitor voltage balance method according to claim 1, which is characterized in that straight
In the crossing process for flowing failure, the detection of bridge arm current direct current biasing is enabled, when bridge arm current is bias state, starts exchange side
Reactive power increase mechanism, MMC transverters allow power bracket in, continue to increase the definite value Q of reactive powerref, until
Complete bias state disappears.
4. hybrid MMC half-bridges submodule capacitor voltage balance method according to claim 3, which is characterized in that when straight
After the completion of flowing fault traversing, when system restores normal, exits reactive power and increase mechanism.
5. hybrid MMC half-bridges submodule capacitor voltage balance method according to claim 3, which is characterized in that system
When restoring normal, by QrefRevert to the definite value before DC Line Fault.
6. hybrid MMC half-bridges submodule capacitor voltage balance method according to claim 1, which is characterized in that mixing
In formula MMC, full-bridge submodule accounting is 45%~55%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810668992.3A CN108809132B (en) | 2018-06-26 | 2018-06-26 | Hybrid MMC half-bridge submodule capacitor voltage balancing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810668992.3A CN108809132B (en) | 2018-06-26 | 2018-06-26 | Hybrid MMC half-bridge submodule capacitor voltage balancing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108809132A true CN108809132A (en) | 2018-11-13 |
| CN108809132B CN108809132B (en) | 2020-04-17 |
Family
ID=64071798
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810668992.3A Active CN108809132B (en) | 2018-06-26 | 2018-06-26 | Hybrid MMC half-bridge submodule capacitor voltage balancing method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108809132B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111509741A (en) * | 2020-04-20 | 2020-08-07 | 兰州理工大学 | Interphase power balance control method for micro-grid with MMC half-bridge series structure |
| CN112134470A (en) * | 2020-08-07 | 2020-12-25 | 国网浙江省电力有限公司电力科学研究院 | Submodule proportion constraint determining method for realizing reliable charging of mixed MMC (Modular multilevel converter) |
| CN117040082A (en) * | 2023-10-08 | 2023-11-10 | 国网江苏省电力有限公司电力科学研究院 | M3C converter bridge arm non-invasive precharge method, device, equipment and medium |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104901524A (en) * | 2015-05-26 | 2015-09-09 | 清华大学 | DC bipolar short-circuit fault crossing method for modular multilevel converter |
| CN105656070A (en) * | 2016-03-11 | 2016-06-08 | 特变电工新疆新能源股份有限公司 | Method for controlling fault ride-through of power grid of flexible direct-current transmission system |
| CN106026163A (en) * | 2016-05-27 | 2016-10-12 | 南京工程学院 | MMC-based low-voltage ride through control method and system of photovoltaic grid-connected inverter |
| CN106160545A (en) * | 2016-07-06 | 2016-11-23 | 清华大学 | A kind of brachium pontis hybrid bipolar modular multi-level converter |
| CN107659192A (en) * | 2017-09-26 | 2018-02-02 | 许继集团有限公司 | A kind of current conversion station and its valve group, which are thrown, moves back process Neutron module pressure equalizing control method |
-
2018
- 2018-06-26 CN CN201810668992.3A patent/CN108809132B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104901524A (en) * | 2015-05-26 | 2015-09-09 | 清华大学 | DC bipolar short-circuit fault crossing method for modular multilevel converter |
| CN105656070A (en) * | 2016-03-11 | 2016-06-08 | 特变电工新疆新能源股份有限公司 | Method for controlling fault ride-through of power grid of flexible direct-current transmission system |
| CN106026163A (en) * | 2016-05-27 | 2016-10-12 | 南京工程学院 | MMC-based low-voltage ride through control method and system of photovoltaic grid-connected inverter |
| CN106160545A (en) * | 2016-07-06 | 2016-11-23 | 清华大学 | A kind of brachium pontis hybrid bipolar modular multi-level converter |
| CN107659192A (en) * | 2017-09-26 | 2018-02-02 | 许继集团有限公司 | A kind of current conversion station and its valve group, which are thrown, moves back process Neutron module pressure equalizing control method |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111509741A (en) * | 2020-04-20 | 2020-08-07 | 兰州理工大学 | Interphase power balance control method for micro-grid with MMC half-bridge series structure |
| CN112134470A (en) * | 2020-08-07 | 2020-12-25 | 国网浙江省电力有限公司电力科学研究院 | Submodule proportion constraint determining method for realizing reliable charging of mixed MMC (Modular multilevel converter) |
| CN112134470B (en) * | 2020-08-07 | 2021-08-27 | 国网浙江省电力有限公司电力科学研究院 | Submodule proportion constraint determining method for realizing reliable charging of mixed MMC (Modular multilevel converter) |
| CN117040082A (en) * | 2023-10-08 | 2023-11-10 | 国网江苏省电力有限公司电力科学研究院 | M3C converter bridge arm non-invasive precharge method, device, equipment and medium |
| CN117040082B (en) * | 2023-10-08 | 2024-01-05 | 国网江苏省电力有限公司电力科学研究院 | M3C converter bridge arm non-invasive precharge method, device, equipment and medium |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108809132B (en) | 2020-04-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN207559578U (en) | Hybrid direct-current power transmission system and fault ride-through system with hybrid MMC (modular multilevel converter) layered access | |
| WO2017152720A1 (en) | Method and apparatus for controlling hybrid direct-current transmission system | |
| CN106990309B (en) | Converter valve steady-state operation test device and method adopting alternating-current test power supply | |
| CN108777492A (en) | The pouring-in hybrid MMC half-bridges submodule capacitor voltage balance method of circulation | |
| CN113938037B (en) | Modular multilevel converter, fault ride-through method and electronic equipment | |
| CN102630369A (en) | Power conversion device | |
| CN103715930B (en) | A kind of method promoting flexible direct current power transmission system capacity | |
| CN108809132A (en) | Hybrid MMC half-bridges submodule capacitor voltage balance method | |
| CN104795834A (en) | Hybrid direct-current transmission topology structure and control method | |
| CN105207504A (en) | Half-bridge and full-bridge mixed type MMC topology with voltage enhancement characteristic | |
| CN109586328B (en) | Economical single-end cascade hybrid direct-current power transmission system with bidirectional flowing power flow | |
| CN109194137A (en) | A kind of modular solid-state transformer based on three level of half-bridge cascade connection type | |
| CN106997012B (en) | Converter valve steady-state operation test device and method adopting capacitor to bear bias voltage | |
| CN106981980A (en) | A kind of full-bridge MMC starts control method and system | |
| CN102545675B (en) | Hybrid series H-bridge multi-level grid-connected inverter direct current bus voltage control method | |
| CN106787859A (en) | Combined three phase single-stage APFC converters and its control device based on full bridge structure | |
| CN103762879B (en) | Single-phase three switches set MMC inverter and the control methods thereof of dual output without direct current biasing | |
| CN109980981A (en) | Mixed type MMC thermal stress unevenness based on active bypass and symmetric modulation stabilizes method | |
| CN109474193A (en) | A kind of modular solid-state transformer based on three level of diode clamp bit-type | |
| WO2023216705A1 (en) | Power conversion circuit and power supply system | |
| CN109617113B (en) | Device and method for mutual conversion between direct current power and alternating current power control targets | |
| CN103762881B (en) | Single-phase three switches set MMC inverter and the control methods thereof of dual output | |
| CN105140949A (en) | Hybrid direct-current power transmission system | |
| CN109742783A (en) | Hybrid HVDC system voltage source type inverter exits method and device online | |
| CN103762863B (en) | N inputs three-phase 3N+3 switches set MMC rectifier and control method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CP01 | Change in the name or title of a patent holder |
Address after: 710077 No. 69 Jinye Road, Yanta District, Xi'an City, Shaanxi Province Patentee after: Xi'an XD Digital Technology Co.,Ltd. Address before: 710077 No. 69 Jinye Road, Yanta District, Xi'an City, Shaanxi Province Patentee before: XI'AN DUANYI TECHNOLOGY Co.,Ltd. |
|
| CP01 | Change in the name or title of a patent holder |