CN106356880B - A kind of MMC commutation systems and its fault tolerant control method - Google Patents
A kind of MMC commutation systems and its fault tolerant control method Download PDFInfo
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- CN106356880B CN106356880B CN201610797502.0A CN201610797502A CN106356880B CN 106356880 B CN106356880 B CN 106356880B CN 201610797502 A CN201610797502 A CN 201610797502A CN 106356880 B CN106356880 B CN 106356880B
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Classifications
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- 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
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- 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
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
- H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
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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
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- 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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Abstract
The present invention relates to a kind of MMC commutation systems and its fault tolerant control methods, the commutation system includes m × n MMC convertor unit, constitute m × n rank matrix, each MMC convertor unit is matrix unit one of in the matrix, the matrix unit for belonging to same row is sequentially connected, and the matrix unit for belonging to same a line is sequentially connected；It is both provided at least one full-bridge submodule on every bridge arm in each MMC convertor units.The MMC commutation systems are divided into three layers of progress faults-tolerant control, first layer control is matrix unit faults-tolerant control, the second layer is row matrix faults-tolerant control, third layer is rectangular array faults-tolerant control, by matrix unit, the faults-tolerant control of three levels of row matrix and rectangular array, the crossing redundancy faults-tolerant control of flexible converter system is realized, industry blank has been filled up, high-voltage large-capacity flexible converter system reliability is greatly improved, industry popularization is conducive to.
Description
Technical field
The present invention relates to a kind of MMC commutation systems and its fault tolerant control methods.
Background technology
Currently, Traditional DC transmission system (also known as line commutation transverter HVDC transmission system, Line
Commutated Converter Based High Voltage Direct Current, LCC-HVDC) due to its technology at
Ripe, transmission line capability is high, active power quickly be used widely by the advantages such as controllable.But there is inversions for LCC-HVDC systems
It stands commutation failure, the defects of can not powering to weak AC system, needing to consume a large amount of reactive powers in operational process, in certain journey
Its development is restricted on degree.
With the development of electric power science and technology, the voltage source converter high voltage direct current based on all-controlling power electronics device
(Voltage Source Converter Based High Voltage Direct Current, VSC-HVDC) is transmitted electricity because of it
Independent active and reactive control ability, without commutation failure risk, can be passive island with power many advantages, such as obtain academia with
The favor of industrial quarters, Chinese scholar are named as flexible DC transmission technology.
Flexible direct current power transmission system based on MMC is with switching frequency is relatively low, switching loss is small, is not necessarily to alternating current filter group
The advantages that strong with autgmentability, becomes the main trend of flexible direct current power transmission system.But it conventional is made of submodule MMC
MMC topological structures disclosed in flexible converter system, such as Chinese patent application file application No. is 201410400214.8,
Since the capacitance grade of single transverter is relatively low, to constrain its utilization in long-distance and large-capacity power transmission occasion.
Invention content
The object of the present invention is to provide a kind of MMC commutation systems and its fault tolerant control methods, to solve traditional flexibility
The relatively low problem of commutation system capacitance grade.
To achieve the above object, the solution of the present invention includes a kind of MMC commutation systems, including m × n MMC convertor unit,
M × n rank matrix is constituted, each MMC convertor unit is matrix unit one of in the matrix, belongs to same row
Matrix unit is sequentially connected, and the matrix unit for belonging to same a line is sequentially connected；
It is both provided at least one full-bridge submodule on every bridge arm in each MMC convertor units.
Every bridge arm in each MMC convertor units is by full-bridge submodule and half-bridge submodule structure according to set proportion
At.
A kind of MMC commutation system fault tolerant control methods being exclusively used in above-mentioned MMC commutation systems, including three layers of faults-tolerant control,
First layer control is matrix unit faults-tolerant control, and the second layer is row matrix faults-tolerant control, and third layer is rectangular array faults-tolerant control,
The first layer faults-tolerant control is：The condition met according to the sub-module fault rate in matrix unit is come to matrix list
Member is correspondingly controlled；The sub-module fault rate is the number of the failure submodule on some bridge arm and the bridge arm in volume
Determine the ratio of the maximal submodule number put into when DC voltage operation；
The second layer faults-tolerant control is：When the failure bridge arm of some matrix unit in some row matrix perfects son
When the voltage control instructions of module are more than the rated value of the first setting multiple, the second layer is carried out to the row matrix and is controlled, profit
The DC voltage of this row matrix is reduced to the second of the rated value to set multiple by the ability that negative pressure is exported with full-bridge submodule；
It is not have faulty submodule in the bridge arm to break down that the failure bridge arm, which perfects submodule,；
The third layer faults-tolerant control is：According to the fault type of some matrix unit in some rectangular array to this
Commutation system is correspondingly controlled.
The condition that the sub-module fault rate according in matrix unit meets is realized correspondingly to be carried out to matrix unit
The means correspondingly controlled are：
When sub-module fault occurs for matrix unit, failure submodule is bypassed first with by-pass switch, is then detected
Bridge arm sub-module fault rate, when failure rate is less than setting value, control input redundancy submodule is made pair with replacing failure submodule
Answer the voltage that bridge arm exports constant；When high failure rate is in the setting value, each normal submodule on failure bridge arm is promoted
The voltage of block output, so that the matrix unit symmetrical operation.
In the second layer faults-tolerant control, when the ability for exporting negative pressure using full-bridge submodule cannot be by homography row
DC voltage be reduced to the rated value second set multiple when, control bypass matrix list all in the row matrix
Member.
In the second layer faults-tolerant control, the bridge arm electricity of all matrix units in some described row matrix is detected
Stream, and obtain maximum bridge arm current, when maximum bridge arm current is in the current stress tolerance range of control switch, the change of current
System maintains former Power operation, and all row matrixs distribute the output work of commutation system according to the ratio of respective DC voltage
Rate；When maximum bridge arm current is not in the current stress tolerance range of control switch, the output power of commutation system is reduced,
And all row matrixs are run with the peak power output allowed.
After the control bypasses matrix unit all in the row matrix, detection perfects all in row matrix
The bridge arm current of matrix unit, and obtain maximum bridge arm current, when maximum bridge arm current is in the current stress of control switch
When in tolerance range, commutation system, which perfects row matrix, distributes the output work of commutation system according to the ratio of respective DC voltage
Rate；When maximum bridge arm current is not in the current stress tolerance range of control switch, the output power of commutation system is reduced,
Perfect row matrix and is run with the peak power output allowed；Wherein, it is in commutation system in addition to being bypassed to perfect row matrix
All row matrixs except row matrix.
Realize that the fault type according to some matrix unit in some rectangular array carries out the commutation system
The means correspondingly controlled are：
First, it is determined that the fault type of the matrix unit；
Then, when for open fault, it is latched the matrix unit；When for short trouble, colleague is perfected into row square first
Array element output voltage control is zero, and tripping colleague perfects the corresponding AC circuit breaker of column matrix unit, then control colleague
Rectangular array matrix unit all bypasses；
The colleague perfects column matrix unit and refers to：With the matrix unit of failure be in same a line, be not belonging to it is same
Row and the matrix unit not broken down；
Colleague's rectangular array matrix unit refers to：With the matrix unit of failure be in same a line, be not belonging to it is same
The matrix unit of row.
After for open fault control accordingly, the bridge arm that all colleagues perfect in column matrix unit is detected
Electric current finds maximum current value, when maximum current value is in control switching current stress tolerance range, all colleagues
Perfect column matrix unit and increases power to maintain power-balance to run, when maximum current value is resistance to beyond control switching current stress
When by range, then matrix commutation system output power is reduced, the maximum current for perfecting the permission of column matrix unit according to colleague carries out
Power transmission；
After for short trouble control accordingly, detection perfects the bridge in matrix unit all in row matrix
Arm electric current finds maximum current value, when maximum current value is in control switching current stress tolerance range, perfects matrix
Row increases power to maintain power-balance to run；When maximum current value exceeds current stress tolerance range, then matrix is reduced
Commutation system output power is transmitted according to the maximum power for perfecting row matrix permission；The row matrix that perfects is change of current system
The row matrix of ffault matrix unit is free of in system.
The size of the priority of first layer faults-tolerant control, second layer faults-tolerant control and third layer faults-tolerant control is：First layer
The priority of faults-tolerant control is more than the priority of second layer faults-tolerant control, and the priority of second layer faults-tolerant control is held more than third layer
The priority of mistake control.
MMC commutation systems provided by the invention are considered as a matrix on the whole, and each matrix unit is that a MMC is changed
Device is flowed, so the commutation system using MMC as basic convertor unit, by way of series boosting and flow increasing in parallel, constitutes square
The requirement of high-voltage large-capacity may be implemented using the matrix form combination of transverter for configuration high-voltage large-capacity flexible converter system, and
And realize that the flexible of alternating current-direct current failure passes through control by the full-bridge submodule in each MMC transverters；Meanwhile matrix form group
The redundancy fault-tolerant ability of entire commutation system can be improved by closing.
Due to being still in initial stage for the research of combined type flexible DC converter at present, especially for matrix form
Flexible converter system coordination control ＆ protection strategy etc. is also in space state, more without matrix form flexible converter System Fault Tolerance control
The relevant report of strategy is made, so, commutation system provided by the invention is of great significance, and can be obviously improved large capacity and change
The research and development progress of streaming system.
Also, matrix form MMC commutation systems provided by the invention are based on, the present invention also provides a kind of points of commutation system
Hierarchical redundancy fault tolerant control method realizes flexibility by matrix unit, the faults-tolerant control of three levels of row matrix and rectangular array
The crossing redundancy faults-tolerant control of commutation system, has filled up industry blank, and greatly improving high-voltage large-capacity flexible converter system can
By property, be conducive to industry popularization.
Description of the drawings
Fig. 1 is MMC commutation systems overall structure diagram provided by the invention；
Fig. 2 is the topological structure schematic diagram of half-bridge submodule；
Fig. 3 is the topological structure schematic diagram of full-bridge submodule；
Fig. 4 is overall faults-tolerant control strategic process schematic diagram；
Fig. 5 is the faults-tolerant control strategic process schematic diagram of matrix unit level；
Fig. 6 is the faults-tolerant control strategic process schematic diagram of row matrix level；
Fig. 7 is the faults-tolerant control strategic process schematic diagram of rectangular array level.
Specific implementation mode
The present invention will be further described in detail below in conjunction with the accompanying drawings.
Fig. 1 gives the matrix form flexible converter system topology based on submodule mixed type MMC inverter units, should
Topology includes m × n submodule mixed type MMC inverter unit, this m × n MMC inverter unit constitutes a matrix, should
Matrix unit in matrix is MMC transverters.Wherein m represents the matrix line number of matrix form commutation system, the i.e. series connection of MMC units
Quantity, m determine the DC voltage level of matrix form commutation system；N represents the matrix columns of matrix form commutation system, i.e. MMC
The quantity in parallel of unit string, n determine the DC current grade of matrix form commutation system；M and n has codetermined the matrix form change of current
Power system capacity.
For the ease of faults-tolerant control, at least one full-bridge is both provided in each bridge arm in each MMC inverter units
Submodule, further, in the present embodiment, each bridge arm in each MMC inverter units is by full-bridge submodule and half
Bridge submodule is constituted according to set proportion.Half-bridge submodule and full-bridge submodule are with all-controlling power electronics device such as IGBT
Basis is constituted, and topological structure is as shown in Figure 2 and Figure 3, wherein T represents full-control type power electronic switching device, D representation switch devices
Part anti-paralleled diode, S represent by-pass switch, and C represents submodule DC capacitor.
Based on above-mentioned matrix form MMC commutation systems, the present invention also provides a kind of faults-tolerant control sides of the MMC commutation systems
Method is based on matrix structure, carries out faults-tolerant control from three matrix unit, row matrix and rectangular array levels respectively.
As shown in figure 4, preferentially matching between giving three hierarchical redundancy fault-tolerance approaches is logical, wherein first layer
It is secondary --- the control of matrix unit is basis, it should which preferential to ensure to implement, second level --- the control of row matrix is first
The tight fit of a level, it should which suboptimum ensures to implement, and the control of third level --- rectangular array is that failure further deteriorates
Fault-tolerant means, can implement finally.First level, the inverter unit fault tolerant control method in matrix, to greatest extent
Ensure commutation system basic equipment availability, higher level fault-tolerant basic guarantee is provided to be follow-up；Second level, row matrix hold
Wrong control method, to ensure the DC voltage enabling capabilities of commutation system to greatest extent；Third level, rectangular array faults-tolerant control
Method, to ensure the DC current enabling capabilities of commutation system to greatest extent.
The faults-tolerant control of these three levels is illustrated respectively below.
As shown in figure 5, for the flow chart of the first level, that is, matrix unit faults-tolerant control.For any one matrix unit,
When sub-module fault occurs for the matrix unit, failure submodule is bypassed first with by-pass switch S, then detects bridge arm submodule
Block failure rate.Sub-module fault rate is that the number of the failure submodule on some bridge arm is transported with the bridge arm in rated direct voltage
The ratio of the maximal submodule number put into when row.In the present embodiment, a calculation formula of sub-module fault rate is given, is seen
Formula (1).
In formula：NsumThe maximal submodule quantity that bridge arm need to be put into when being run for rated direct voltage, NfFor failure in bridge arm
The quantity of submodule.
When the failure submodule number on some bridge arm is less, i.e., the sub-module fault rate of the bridge arm is set less than one
When fixed threshold value (the present embodiment is for 5%), to ensure the fast response characteristic of commutation system after failure, according to submodule electricity
Pressure instructs constant principle to carry out the Pressure and Control that failure bridge arm perfects submodule, i.e. identical as failure submodule of control input
Several redundancy submodules keeps the voltage that the bridge arm exports constant to replace failure submodule；When the failure submodule on the bridge arm
When number is more, i.e., when the sub-module fault rate of the bridge arm is higher than the threshold value of the setting (the present embodiment is for 5%), to prevent
DC voltage and current fluctuation caused by bridge arm energy is unbalanced is excessive, switchs to the submodule voltage increase based on bridge arm energy balance
Faults-tolerant control promotes the voltage that each on the failure bridge arm perfects submodule output, so that the matrix unit is symmetrically transported
Row.Wherein, failure bridge arm perfects submodule and refers to：Have in the bridge arm of sub-module fault, remaining does not break down still just
The submodule often run.
In the present embodiment, the voltage increase for perfecting submodule in failure bridge arm is instructed as shown in formula (2), to maximum journey
Degree ensures the quick and stable redundancy fault-tolerant ability of matrix unit.
In formula：UdcFor matrix unit DC operating voltage.
Such as：Matrix unit will export the voltage of 100kV, and the voltage of each submodule is 2kV, then needs to put into bridge arm
50 sub- block coupled in series, to reach the output voltage of 100kV.
When there is sub-module fault at this time, output voltage can be kept constant by the input of redundant module.A such as bridge
Arm has 60 submodules, then has 10 module redundancies when exporting 100kV voltages, when there are one sub-module fault, puts into one
The redundant module of 2kV, the voltage for exporting 100kV is unaffected, the advantage of doing so is that transient response is fast；This is exactly so-called
The constant fault-tolerant strategy of submodule voltage.
But since MMC is 6 bridge arm structure of three-phase, when the failure submodule in single bridge arm is more (generally more than 5%
After), the submodule number that other perfect normal operation in phase bridge arm is more, and the capacitive energy storage under same voltage is just high, inevitable
Leading to asymmetric storage energy operation between MMC unit bridge arms, the consequence of asymmetric operation is exactly to lead to two double-frequency fluctuations of DC voltage,
Influence straight-flow system stability and control accuracy.Therefore response is fast in order to balance and failure submodule it is more after cause MMC not right
Claim operation aggravation, proposition the voltage of failure bridge arm submodule is promoted, although failure bridge arm in this way compared with perfecting bridge arm,
Submodule number is few, but due to after single submodule voltage increase energy storage increase, MMC units can restore symmetrical operation,
Avoid two double-frequency fluctuations of DC voltage.It is implemented as：Using formula (2) failure bridge arm submodule electricity is promoted to calculate
Desired value is pressed, then the submodule input number of the bridge arm is removed by 100kV in the result of calculation of formula (2), i.e. input
Number will be reduced, and failure bridge arm submodule can be charged to the numerical value obtained using formula (2) in this process, therefore can sacrifice one
Fixed response characteristic.
As shown in fig. 6, being the second level, that is, row matrix faults-tolerant control flow chart.For some row matrix, when the matrix
When some matrix unit in row breaks down, the voltage control instructions value for perfecting submodule of failure bridge arm is set more than first
When determining the rated value of multiple (the present embodiment is for 105%), implement the control of second level to the row matrix.Wherein, therefore
The voltage control instructions value for perfecting submodule of barrier bridge arm can be all voltages for perfecting submodule in the failure bridge arm
Average value, can also be the maximum value in all voltages for perfecting submodule in the failure bridge arm, or use other
Mode obtains, and the present embodiment provides a calculation formula by taking average value as an example, as shown in formula (3).
In above formula：For the average value of all output voltages for perfecting submodule in failure bridge arm；∑Usm_
Arm is bridge arm voltage；NtotalFor the sum of the submodule on a bridge arm；LPF is low-pass first order filter, filter cutoff frequency
By 0.707 times of connection AC network fundamental frequency；NfFor the number of the failure submodule on the bridge arm.
When submodule average voltage is more than the first setting multiple (105%) of rated value, then it is in the row matrix
All matrix units export the ability of negative pressure using full-bridge submodule, unified that this row matrix DC voltage is reduced to rated value
Second setting multiple (the present embodiment is for 95%), so recycle, with reduce operation submodule overvoltage bypass risk.
Meanwhile the bridge arm current in all matrix units in the row matrix is detected, multiple current values are obtained, it is found
In maximum bridge arm current, when maximum bridge arm current control switch (IGBT) current stress tolerance range in when, this is changed
Streaming system is run and is controlled according to original transducing power, and all row matrixs divide according to the ratio of respective DC voltage
Output power with commutation system；When maximum bridge arm current is not in the current stress tolerance range of control switch (IGBT)
When, the output power of commutation system is reduced, and all row matrixs are run with the peak power output allowed.Wherein, control is opened
The current stress tolerance range of pass is switched by control, i.e. IGBT is determined, is the index parameter of IGBT, as long as IGBT is fixed,
Its current stress tolerance range is also just fixed.
Wherein, the formula that row matrix distributes the output power of commutation system according to the ratio of respective DC voltage is following
Formula (4).
In addition, when full-bridge submodule negative pressure fan-out capability runs out, stop DC decompression cycle；Also, when beyond complete
When bridge submodule negative pressure fan-out capability, i.e., when the ability for exporting negative pressure using full-bridge submodule cannot be by the direct current of the row matrix
Down to the second setting multiple (the present embodiment is for 95%) of above-mentioned rated value, control, which bypasses in the row matrix, owns for pressure drop
Matrix unit.
Meanwhile after control bypasses matrix units all in the row matrix, detecting all perfect in row matrix
All matrix units in bridge arm current, obtain multiple current values, find maximum bridge arm current, when maximum bridge
When arm electric current is in the current stress tolerance range of control switch (IGBT), commutation system is run according to original transducing power
And control, and all output powers for perfecting row matrix and being distributed according to the ratio of respective DC voltage commutation system；When most
When big bridge arm current is not in the current stress tolerance range of control switch (IGBT), the output power of commutation system is reduced,
And all peak power output operations for perfecting row matrix to allow.Wherein, controlling the current stress tolerance range of switch is
It being switched by control, i.e. IGBT is determined, is the index parameter of IGBT, as long as IGBT is fixed, current stress tolerance range
It is fixed.
Wherein, perfect row matrix and distributed according to the ratio of respective DC voltage the formula of the output power of commutation system
It is allocated according to above-mentioned formula (4).Perfecting row matrix refers to：Not by the row matrix still in continuous service of integral bypass.
As shown in fig. 7, being third level, that is, rectangular array faults-tolerant control flow chart.The thinking of the control of the rectangular array is：
The commutation system is correspondingly controlled according to the fault type of some matrix unit in some rectangular array, here
Fault type is divided into two kinds of open circuit and short circuit.
First, the malfunction of the rectangular array, the i.e. fault type of ffault matrix unit in the rectangular array are detected, when for
When open fault, it is latched failure MMC convertor units；When for short trouble, colleague is perfected into the output of column matrix unit first
Voltage control is zero, and tripping colleague perfects the corresponding AC circuit breaker of column matrix unit, then control colleague matrix column matrix
Unit all bypasses.Wherein, colleague perfects column matrix unit and refers to：It is in same a line with the matrix unit of failure, do not belong to
The matrix unit not broken down in same row and；Colleague rectangular array matrix unit refer to：At the matrix unit of failure
In same a line, it is not belonging to the matrix unit of same row.So colleague's rectangular array matrix unit, which includes colleague, perfects column matrix list
Member.
After for open fault control accordingly, the bridge arm that whole colleagues perfects in column matrix unit is detected
Electric current finds maximum current value, and when the maximum current value is when controlling in switching current stress tolerance range, all is same
Row perfects column matrix unit and increases power to maintain power-balance to run, when the maximum current value is resistant to model beyond current stress
When enclosing, then matrix commutation system output power is reduced, the maximum current for perfecting the permission of column matrix unit according to colleague carries out power
Transmission.
After for short trouble control accordingly, detection perfects the bridge in matrix unit all in row matrix
Arm electric current finds maximum current value, when the maximum current value is in control switching current stress tolerance range, perfects square
Battle array row increases power to maintain power-balance to run；When the maximum current value exceeds current stress tolerance range, then reduce
Matrix commutation system output power is transmitted according to the maximum power for perfecting row matrix permission.
Above-mentioned commutation system is illustrated with one 2 × 2 ± 1000kV/12000MW matrix form MMC commutation system below
Control method.
The MMC units of above-mentioned matrix form MMC systems are 1000kV/3000MW voltage source converters, main electrical parameters
For：Using the IGBT device of 4500V/3000A specifications, submodule block specifications are 2500V/3000A, consider 10% redundancy submodule
Configuration, then the submodule quantity of the single bridge arm of MMC units is 1000/2.5 × 1.1=440；Consider zero direct current of MMC units
The accounting of pressure control ability, half-bridge submodule and full-bridge submodule is 1:1；The valve side zero load ac line voltage of MMC units is effective
Value is designed as 520kV.
Carry out that the first level is fault-tolerant to be illustrated first, when 10 sub-module faults occur for bridge arm on the A of MMC11, this
When sub-module fault rate be 10/400=2.5%, should maintain MMC11 submodule voltages are constant to continue to run with, put into 10 redundancies
Submodule replaces failure submodule；As MMC11, some bridge arm sub-module fault adds up to be 20, i.e., failure rate reaches 5%, increases
The big output voltage values for perfecting submodule, i.e., it is sqrt (400/ MMC11 failure bridge arms to be perfected the control of submodule voltage instruction
(400-20)) × 2500=2564.9V, entire MMC commutation systems continuous service.
As MMC11 since sub-module fault increase causes failure bridge arm to perfect the volume that submodule control instruction is more than 1.05 times
When definite value, the second level, that is, row matrix faults-tolerant control flow will be started, the single bridge arm failure submodule of MMC11 can be calculated at this time
Number is at least 400-400/1.05^2=38 (rounding up), and failure bridge arm at this time perfects submodule voltage instruction as sqrt
(400/ (400-38)) × 2500=1.0512 × 2500=2627.9V；Therefore the full-bridge submodule of MMC11 and MMC12 is utilized
Negative voltage ability is exported, control the first row DC voltage Vdc1 is 1000 × 0.95=950kV, if MMC12 is without son at this time
Module failure, then its submodule voltage instruction value should be 950e3/400=2375V, and have 38 failure submodule bridges in MMC11
The submodule voltage instruction value that perfects of arm should be sqrt (400/ (400-38)) × 2375=2496.5V；According to the volume of 3000MW
Determine transducing power calculating, the bridge arm current stress of the first row matrix is 3000e6/950e3/3+3000e6/520e3/ at this time
1.732/2=2718.1A, is less than the IGBT device current stress permissible value of 3000A, and system still can be with 3000MW × 4
12000MW oeprations at full load；
When leading to the first row matrix by integral bypass due to MMC11 sub-module faults, system can only utilize the second row
Power transmission is carried out, is only capable of conveying 6000MW power at this time, is i.e. volume operation will drop in system.
It finally carries out third level, that is, rectangular array faults-tolerant control to illustrate, still by taking MMC11 as an example, when MMC11 is open circuit
When failure, it is latched MMC11 convertor units first；It is limited by current stress, system will lose the power of half, and system maximum can
To operate under ± 1000kV/6000MW power ratings；When MMC11 is short trouble, MMC12 output DC voltages are controlled immediately
It is made as zero, then the corresponding AC circuit breakers of tripping MMC12 issue MMC12 bypass commands；It is limited by current stress, system
The power of half will be lost, system maximum may operate under -1000kV/6000MW power ratings.
Specific embodiment is presented above, but the present invention is not limited to described embodiment.The base of the present invention
This thinking is above-mentioned basic scheme, and for those of ordinary skill in the art, various changes are designed in introduction according to the present invention
The model of shape, formula, parameter do not need to spend creative work.It is right without departing from the principles and spirit of the present invention
The change, modification, replacement and modification that embodiment carries out are still fallen in protection scope of the present invention.
Claims (8)
1. a kind of MMC commutation systems fault tolerant control method, which is characterized in that this method is applied to a kind of MMC commutation systems, described
MMC commutation systems include m × n MMC convertor unit, constitute m × n rank matrix, each MMC convertor unit is the matrix
In one of matrix unit, the matrix unit for belonging to same row be sequentially connected, the matrix unit for belonging to same a line connects successively
It connects；It is both provided at least one full-bridge submodule on every bridge arm in each MMC convertor units；
This method includes three layers of faults-tolerant control, and first layer faults-tolerant control is matrix unit faults-tolerant control, and second layer faults-tolerant control is
Row matrix faults-tolerant control, third layer faults-tolerant control are rectangular array faults-tolerant control,
The first layer faults-tolerant control is：According in matrix unit sub-module fault rate meet condition come to matrix unit into
Row correspondingly controls；The sub-module fault rate is the number of the failure submodule on some bridge arm and the bridge arm specified straight
The ratio of the maximal submodule number put into when galvanic electricity pressure operation；
The second layer faults-tolerant control is：When the failure bridge arm of some matrix unit in some row matrix perfects submodule
Voltage control instructions when being more than the rated value of the first setting multiple, the second layer faults-tolerant control, profit are carried out to the row matrix
The DC voltage of this row matrix is reduced to the second of the rated value to set multiple by the ability that negative pressure is exported with full-bridge submodule；
It is not have faulty submodule in the bridge arm to break down that the failure bridge arm, which perfects submodule,；
The third layer faults-tolerant control is：According to the fault type of some matrix unit in some rectangular array to the change of current
System is correspondingly controlled.
2. MMC commutation systems fault tolerant control method according to claim 1, which is characterized in that realize described according to matrix
The condition that sub-module fault rate in unit meets is come the means correspondingly correspondingly controlled matrix unit：
When sub-module fault occurs for matrix unit, failure submodule is bypassed first with by-pass switch, then detects bridge arm
Sub-module fault rate, when sub-module fault rate is less than setting value, control input redundancy submodule is made with replacing failure submodule
The voltage of corresponding bridge arm output is constant；When sub-module fault rate is higher than the setting value, each on failure bridge arm is promoted
The voltage of normal submodule output, so that the matrix unit symmetrical operation.
3. MMC commutation systems fault tolerant control method according to claim 1, which is characterized in that fault-tolerant in the second layer
In control, when using full-bridge submodule export negative pressure ability the DC voltage of homography row cannot be reduced to it is described specified
When the second setting multiple of value, control bypasses matrix unit all in the row matrix.
4. MMC commutation systems fault tolerant control method according to claim 1, which is characterized in that fault-tolerant in the second layer
In control, the bridge arm current of all matrix units in some described row matrix is detected, and obtains maximum bridge arm current,
When maximum bridge arm current is in the current stress tolerance range of control switch, commutation system maintains former Power operation, and institute
Some row matrixs distribute the output power of commutation system according to the ratio of respective DC voltage；When maximum bridge arm current does not exist
When controlling in the current stress tolerance range of switch, reduce the output power of commutation system, and all row matrixs are to allow
Peak power output is run.
5. MMC commutation systems fault tolerant control method according to claim 3, which is characterized in that bypassed in the control
In the row matrix after all matrix units, detection perfects the bridge arm current of all matrix units in row matrix, and obtains
Go out maximum bridge arm current, when maximum bridge arm current is in the current stress tolerance range of control switch, commutation system is strong
Complete matrix row distributes the output power of commutation system according to the ratio of respective DC voltage；When maximum bridge arm current is not being controlled
When making in the current stress tolerance range of switch, the output power of commutation system is reduced, the maximum for perfecting row matrix to allow is defeated
Go out Power operation；Wherein, it is all row matrixs in commutation system other than the row matrix being bypassed to perfect row matrix.
6. MMC commutation systems fault tolerant control method according to claim 1, which is characterized in that realize described according to a certain
The means that the fault type of some matrix unit in a rectangular array correspondingly controls the commutation system are：
First, it is determined that the fault type of the matrix unit；
Then, when for open fault, it is latched the matrix unit；When for short trouble, colleague is perfected into column matrix list first
First output voltage control is zero, and tripping colleague perfects the corresponding AC circuit breaker of column matrix unit, then controls same row matrix
Column matrix unit all bypasses；
The colleague perfects column matrix unit and refers to：Be in same a line with the matrix unit of failure, be not belonging to same row and
The matrix unit not broken down；
Colleague's rectangular array matrix unit refers to：It is in same a line with the matrix unit of failure, is not belonging to same row
Matrix unit.
7. MMC commutation systems fault tolerant control method according to claim 6, which is characterized in that
After for open fault control accordingly, the bridge arm electricity that all colleagues perfect in column matrix unit is detected
Stream, finds maximum current value, and when maximum current value is when controlling in switching current stress tolerance range, all colleagues are strong
Full column matrix unit increases power to maintain power-balance to run, when maximum current value is beyond control switching current stress tolerance
When range, then matrix commutation system output power is reduced, the maximum current for perfecting the permission of column matrix unit according to colleague carries out work(
Rate is transmitted；
After for short trouble control accordingly, detection perfects the electricity of the bridge arm in matrix unit all in row matrix
Stream, finds maximum current value, when maximum current value is in control switching current stress tolerance range, perfects row matrix increasing
Add power to maintain power-balance to run；When maximum current value exceeds current stress tolerance range, then the matrix change of current is reduced
System output power is transmitted according to the maximum power for perfecting row matrix permission；The row matrix that perfects is in commutation system
Row matrix without ffault matrix unit.
8. MMC commutation systems fault tolerant control method according to claim 1, which is characterized in that first layer faults-tolerant control,
The size of the priority of two layers of faults-tolerant control and third layer faults-tolerant control is：The priority of first layer faults-tolerant control is more than the second layer
The priority of faults-tolerant control, the priority of second layer faults-tolerant control are more than the priority of third layer faults-tolerant control.
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| CN113078835A (en) * | 2021-04-06 | 2021-07-06 | 上海电气集团股份有限公司 | Novel active precharge voltage-sharing method for cascade power electronic device |
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