CN104953571B - A kind of modularization multi-level converter improved structure with DC Line Fault Scavenging activity - Google Patents
A kind of modularization multi-level converter improved structure with DC Line Fault Scavenging activity Download PDFInfo
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- CN104953571B CN104953571B CN201510391732.2A CN201510391732A CN104953571B CN 104953571 B CN104953571 B CN 104953571B CN 201510391732 A CN201510391732 A CN 201510391732A CN 104953571 B CN104953571 B CN 104953571B
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- 230000002000 scavenging effect Effects 0.000 title claims abstract description 7
- 230000001133 acceleration Effects 0.000 claims abstract description 13
- 238000002955 isolation Methods 0.000 claims abstract description 11
- 230000002459 sustained effect Effects 0.000 claims description 9
- 239000003990 capacitor Substances 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 3
- 230000004888 barrier function Effects 0.000 claims 1
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- 238000006243 chemical reaction Methods 0.000 description 2
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- 230000000694 effects Effects 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 238000003672 processing method Methods 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
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Abstract
The invention discloses a kind of modularization multi-level converter improved structure with DC Line Fault Scavenging activity, on the basis of double-thyristor method, one acceleration current limliting module of access of being connected again in each bridge arms of MMC；During system normal operation, all IGCTs are off state, while accelerate the IGBT in current limliting module to be constantly in conducting state；Current-limiting resistance RcIt is constantly in the state of being bypassed；When system dc side is broken down, all IGBTT in MMC submodulesa、TbShut-off, and all IGCTs are open-minded, prevent AC power supply to DC Line Fault point feed-in fault current；All IGBT accelerated in six bridge arms in current limliting module are simultaneously turned off, input accelerates current-limiting resistance Rc, acceleration disturbance, which isolates speed, simultaneously prevents AC excessively stream.The present invention is applied to all DC Line Fault types, increases protection domain；Acceleration disturbance current attenuation speed simultaneously, greatly shortens the time needed for Fault Isolation；The overcurrent that AC is born is reduced, substantially reduces the harm of AC excessively stream.
Description
Technical field
The present invention relates to protecting electrical power system control field, more particularly to a kind of DC Line Fault processing method.
Background technology
Fast-speed direct current Fault Isolation is the key technology of flexible direct current system development.DC Line Fault occurs for flexible direct current system
When, TSD total system down electric current steeply rises, and seriously jeopardizes the safe and reliable operation of system.However, existing transverter can not be real
The self-cleaning of existing DC Line Fault, it is necessary to excision faulty line of taking measures on customs clearance.But during due to DC Line Fault fault current without
Natural zero-crossing point, cause dc circuit breaker blow-out more difficult, therefore the dc circuit breaker technology of Large Copacity also reaches far away business
Industry application level.So a large amount of scholar's primary studies have the converter structure of fault clearance ability and a corresponding control both at home and abroad
Scheme processed.Wherein, double-thyristor method in isolation effect, cost of investment, control complexity etc. due to having advantage, in reality
There is good application prospect in engineering.Double-thyristor method adds antiparallel double-thyristor, this pair in each MMC submodules
IGCT and the 2nd IGBTT in parallelbWith the second sustained diodebForm in parallel.When systems are functioning properly, each MMC
Only one group of IGBT and fly-wheel diode are open-minded in module, and double-thyristor is turned off；When system dc side is broken down, MMC
All IGBTT in submodulea、TbShut-off, and all IGCTs are open-minded, prevent AC power supply to DC Line Fault point feed-in failure
Electric current.However, the three phase short circuit fault due to double-thyristor method by DC side Conversion fault into AC, therefore can cause to exchange
The long-term excessively stream in side；Simultaneous faults electric current is that the resistive component in DC Line Fault loop realizes Natural Attenuation, therefore its failure
Isolation speed can slow down with the close of abort situation, especially when metallicity failure occurs for transverter near exit, need
Long time is wanted to realize Fault Isolation.Corresponding corrective measure solution must be taken above-mentioned not in practical engineering application
Foot.
When DC Line Fault occurs for flexible direct current system, fault overcurrent will have a strong impact on that whole straight-flow system includes exchange
The safe and reliable operation of side, DC side and transverter.Therefore, during DC Line Fault, it is desirable to can quickly cut off faulty line, i.e.,
Certain failure separation method must be taken to isolate DC Line Fault circuit.
Double-thyristor method is due to the advantage in isolation effect, cost of investment, control complexity etc., in Practical Project
With good application prospect.However, the three phase short circuit fault due to double-thyristor method by DC side Conversion fault into AC,
Therefore the long-term excessively stream of AC can be caused；Simultaneous faults electric current is that the resistive component in DC Line Fault loop realizes that nature declines
Subtract, therefore its Fault Isolation speed can slow down with the close of abort situation, and gold especially occurs in transverter near exit
, it is necessary to which long time could realize Fault Isolation during attribute failure.To sum up state double-thyristor method and protection domain be present and be not enough to
And protection fault type it is limited the shortcomings that, therefore must take in practical engineering application corresponding corrective measure solve it is above-mentioned not
Foot.
The content of the invention
In order to overcome the above-mentioned problems of the prior art, the present invention proposes a kind of with DC Line Fault Scavenging activity
MMC improved structures (modular multilevel converter, MMC), double-thyristor is set in MMC submodules, for
Fault Isolation speed be present and had a great influence by abort situation, fault type in double-thyristor method；And AC bears long-time mistake
The deficiencies of electric current, added in each bridge arm and accelerate current limliting module, realize that DC system fault is handled.
The present invention proposes a kind of MMC improved structures with DC Line Fault Scavenging activity, including multiple by MMC submodules
The MMC transverters of composition；The MMC submodules include first, second IGBTTa、Tb, first, second sustained diodea、DbWith
DC capacitor C, connected mode are：One group of the first IGBTT in parallelaWith the first sustained diodea, in parallel with another group second
IGBTTbWith the second sustained diodebForm series connection；The cascaded structure is in parallel with DC capacitor C compositions again；Each MMC submodules
It is middle to add antiparallel double-thyristor, the double-thyristor and the 2nd IGBTT in parallelbWith the second sustained diodebForm in parallel；
Wherein, one acceleration current limliting module of series connection access, the acceleration current limliting module are antiparallel by two in each bridge arm of transverter
First, second current limliting IGBTT1、T2And in parallel current-limiting resistance R therewithcForm；
During system normal operation, only one group of IGBT and fly-wheel diode are open-minded in each MMC submodules；Accelerate current limliting module
Interior all IGBT are open-minded, and double-thyristor is turned off, current-limiting resistance RcIt is constantly in the state of being bypassed；
When system dc side is broken down, all IGBTT in MMC submodulesa、TbShut-off, and all IGCTs are open-minded, resistance
Only AC power supply is to DC Line Fault point feed-in fault current；Six bridge arms accelerate all IGBT in current limliting module to close simultaneously
It is disconnected；
The choosing value of the current-limiting resistance Rc be formula (1), (2), (3) solution common factor：
Above-mentioned formula (1)~(3), tmaxIsolate the higher limit of operation time limit requirement, I to DC Line Fault for systemm_maxIt is fair
Perhaps excessively stream amplitude, UmaxFor the IGBT withstanding voltage upper limits, LrFor bridge arm reactance value, UmFor AC phase voltage amplitude, Idc0To enter
Enter fault clearance moment DC line electric current initial value.
Compared with the prior art, the present invention has the implementation result after following improvement：
(1), acceleration disturbance current attenuation speed, the time needed for Fault Isolation is greatly shortened；
(2), simultaneously, improvement project is applied to all DC Line Fault types, further increases protection domain；
(3), by the equivalent short circuit impedance of AC during increasing Failure elimination, reduce AC bear it is excessively electric
Stream, substantially reduce the harm of AC excessively stream.
Brief description of the drawings
Fig. 1 is DC Line Fault processing method schematic diagram；
Fig. 2 is DC Line Fault removing stage equivalent circuit diagram.In figure：usabcFor the alternating voltage of AC A, B, C phase；
isabcFor the alternating current of AC A, B, C phase；iLa,iLb,iLcRepresent respectively and the continuous electricity of bridge arm reactance corresponding to A, B, C phase
Stream；LrAnd RrRepresent the inductance value and resistance value of bridge arm reactor；RcRepresent the resistance value accelerated in current limliting module；LkAnd RkRepresent
The equivalent inductance value and equivalent resistance of faulty line；idcFor DC line fault electric current.
Embodiment
Below in conjunction with the drawings and the specific embodiments, technical scheme is described in further detail.
To based on double-thyristor method modularization multi-level converter (Modular Multilevel Converter,
MMC) topological structure carries out certain improvement, as shown in Fig. 1 (a)：Each MMC submodule of the double-thyristor method in MMC transverters
It is middle to add antiparallel double-thyristor, on this basis, the present invention one acceleration current limliting mould of series connection access in each bridge arms of MMC
Block, the module resistance R in parallel by two antiparallel IGBT and therewithcForm.In figure：T1、T2For reverse parallel connection
IGBT, RcThe resistance sealed in after occurring for failure in converter bridge arm.
During straight-flow system normal operation, the IGBT of the acceleration current limliting module of series connection is in opening state in each bridge arm.
Now, shown in the circulation path of bridge arm current such as Fig. 1 (b), resistance RcThe state of being bypassed is constantly in, system being capable of normal operation
Without producing added power dissipation.
When system dc side is broken down, all IGBT in MMC submodules are immediately turned off, and open all IGCTs, are hindered
Only AC power supply is to DC Line Fault point feed-in fault current；Six bridge arms are immediately turned off simultaneously accelerates owning in current limliting module
IGBT.Now, the circulation path such as Fig. 1 of fault current (continuing electric current comprising alternating current source supply electric current and bridge arm reactance) in module
(c) shown in.According to fault current circulation path and the working mechanism of double-thyristor method, can obtain at now alternating current-direct current interconnection etc.
It is as shown in Figure 2 to imitate circuit.
Current-limiting resistance RcInput the DC side fault current rate of decay is accelerated, therefore fault current will decay rapidly
To zero, and it is isolated speed and will not be subject abort situation influence.R simultaneouslycInput cause AC equivalent short circuit impedance
Greatly increase, the over-current level of AC during reduction fault clearance.
Consider system to isolating the requirement of speed, AC bear the ability and electronic power switch device of overcurrent
The pressure-resistant upper limit of part, the R being shown belowcChoosing value standard：(formula (1), (2), (3) are the relation of "AND", and work as formula
(1), (2), the common factor of (3) solution are space-time, pay the utmost attention to the solution of formula (3).
Above-mentioned formula (1)~(3), tmaxIsolate the higher limit of operation time limit requirement, I to DC Line Fault for systemm_maxIt is fair
Perhaps excessively stream amplitude, UmaxFor the IGBT withstanding voltage upper limits, LrFor bridge arm reactance value, UmFor AC phase voltage amplitude, Idc0To enter
Enter fault clearance moment DC line electric current initial value.
Claims (2)
1. a kind of modularization multi-level converter improved structure with DC Line Fault Scavenging activity, including multiple MMC submodules
With acceleration current limliting module；The MMC submodules include first, second IGBTTa、Tb, first, second sustained diodea、DbWith
DC capacitor C, connected mode are：One group of the first IGBTT in parallelaWith the first sustained diodea, in parallel with another group second
IGBTTbWith the second sustained diodebForm series connection；The cascaded structure is in parallel with DC capacitor C compositions again；Each MMC simultaneously
Antiparallel double-thyristor is added in module, the double-thyristor and the 2nd IGBTT in parallelbWith the second sustained diodebForm
It is in parallel；Characterized in that, series connection has accessed an acceleration current limliting module in each bridge arms of MMC, the acceleration current limliting module is by two
Antiparallel first, second current limliting IGBTT1、T2And in parallel current-limiting resistance R therewithcForm；
During system normal operation, only one group of IGBT and fly-wheel diode are open-minded in each MMC submodules；Accelerate in current limliting module
All IGBT it is open-minded, double-thyristor is turned off, current-limiting resistance RcIt is constantly in the state of being bypassed；
When system dc side is broken down, all IGBTT in MMC submodulesa、TbShut-off, and all IGCTs are open-minded, prevent to hand over
Side power supply is flowed to DC Line Fault point feed-in fault current；Simultaneously turn off the institute in the acceleration current limliting module on six bridge arms of transverter
There is IGBT, input accelerates current-limiting resistance Rc, the speed of acceleration disturbance isolation, while limiting AC side overcurrent；
The choosing value of the current-limiting resistance Rc be formula (1), (2), (3) solution common factor：
Above-mentioned formula (1)~(3), tmaxIsolate the higher limit of operation time limit requirement, I to DC Line Fault for systemm_maxFor permission
Excessively stream amplitude, UmaxFor the IGBT withstanding voltage upper limits, LrFor bridge arm reactance value, UmFor AC phase voltage amplitude, Idc0To enter event
Barrier removes moment DC line electric current initial value.
2. a kind of modularization multi-level converter improved structure with DC Line Fault Scavenging activity as claimed in claim 1,
Characterized in that, the formula (1), (2), the common factor of solution of (3) are space-time, the choosing value of the current-limiting resistance Rc uses formula
(3) solution.
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Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| GB2550421A (en) * | 2016-05-20 | 2017-11-22 | General Electric Technology Gmbh | Control of voltage source converters |
| CN106787876B (en) * | 2016-12-05 | 2023-08-08 | 特变电工新疆新能源股份有限公司 | Modularized multi-level converter and high-voltage valve group earth fault protection method thereof |
| CN107046278B (en) * | 2017-04-06 | 2019-01-22 | 华北电力大学 | A kind of guard method of the DC Line Fault current limliting module based on voltage source converter |
| CN107658842B (en) * | 2017-11-08 | 2019-11-12 | 华北电力大学 | DC side fault protection system and method based on MMC submodule topology |
| CN108448542A (en) * | 2018-02-07 | 2018-08-24 | 许继集团有限公司 | Sub-modular structure with alternating current-direct current fault clearance ability and MMC topological structures |
| CN109217265B (en) * | 2018-08-24 | 2019-10-11 | 东北电力大学 | A kind of removing DC Line Fault method of electric current transfevent multilevel converter topology |
| CN109687419B (en) * | 2019-02-18 | 2020-05-08 | 福州大学 | Medium-voltage direct-current distribution network fault current limiting method based on capacitance protection |
| CN110048378A (en) * | 2019-04-09 | 2019-07-23 | 东南大学 | A kind of middle bipolar short-circuit protection method of pressure direct current distribution based on semi-bridge type MMC |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104617800A (en) * | 2015-01-30 | 2015-05-13 | 天津大学 | Improved redundancy type MMC current converter structure having direct-current fault current-limiting capacity |
| CN104617757A (en) * | 2015-01-30 | 2015-05-13 | 天津大学 | Improved overvoltage preventing type MMC current converter structure having direct-current fault current-limiting capacity |
| CN104617783A (en) * | 2014-12-29 | 2015-05-13 | 天津大学 | Improved structure of MMC (Modular Multilevel Converter) current converter with direct-current fault current-limiting capacity and isolating method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104617783A (en) * | 2014-12-29 | 2015-05-13 | 天津大学 | Improved structure of MMC (Modular Multilevel Converter) current converter with direct-current fault current-limiting capacity and isolating method |
| CN104617800A (en) * | 2015-01-30 | 2015-05-13 | 天津大学 | Improved redundancy type MMC current converter structure having direct-current fault current-limiting capacity |
| CN104617757A (en) * | 2015-01-30 | 2015-05-13 | 天津大学 | Improved overvoltage preventing type MMC current converter structure having direct-current fault current-limiting capacity |
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