CN109494971A - A kind of flexible HVDC transmission system DC bus be shorted in the case of starting strategy - Google Patents
A kind of flexible HVDC transmission system DC bus be shorted in the case of starting strategy Download PDFInfo
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- CN109494971A CN109494971A CN201811184565.4A CN201811184565A CN109494971A CN 109494971 A CN109494971 A CN 109494971A CN 201811184565 A CN201811184565 A CN 201811184565A CN 109494971 A CN109494971 A CN 109494971A
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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
- H02M1/00—Details of apparatus for conversion
- H02M1/36—Means for starting or stopping converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
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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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- 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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- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
Starting strategy in the case of a kind of flexible HVDC transmission system DC bus short circuit of the present invention, when DC bus is shorted, determine that bridge arm is locking or excision module by module voltage, converter valve is set to charge by lateral comparison and longitudinal comparison mode to module, it solves the problems, such as that the half-bridge module in special circumstances of converter valve DC bus short circuit fills not powering on, and in a certain range by the difference control of module voltage between bridge arm, the problem for avoiding current measurement precision and dead zone from bringing walking direction inaccurate.
Description
Technical field
The present invention relates to flexible direct-current transmission fields, and in particular to a kind of flexible HVDC transmission system DC bus short circuit feelings
Starting strategy under condition.
Background technique
Flexible HVDC transmission system is very suitable to high voltage, large-power occasions with its unique technical advantage, mutual in power grid
Connection, wind farm grid-connected, island power supply, urban power distribution network the fields such as capacity-increasing transformation there is huge engineering advantage.Flexible direct current
Modular multilevel structure is widely used in transmission system, independently can quickly control active power and reactive power, to improve
The stability of system inhibits the fluctuation of system frequency and voltage, improves the steady-state performance of grid-connected AC system.
Flexible HVDC transmission system needs to undergo start-up course before unlock operation, fills module with electricity, drive takes can electricity
Source work.Starting conventional at present includes AC charging and DC charging mode, and under AC charging mode, detection limit is mostly bridge arm
Electric current and voltage on valve side, it is using AC power source that module voltage and DC bus is electric when system includes full-bridge and half-bridge module
Pressure is charged to centainly, and uncontrollable rectifier charging stage half-bridge module charger can be the half of full-bridge modules；Under DC charging mode, hand over
Streaming system end disconnects, and is charged using DC voltage to module, half-bridge module and full-bridge block in uncontrollable rectifier charging stage bridge arm
Charger can be identical.When converter valve failure is thrown online moves back, need that converter valve puts into operation again after trouble hunting,
Starting situation under being shorted there are converter valve DC bus, both the above charge mode are not suitable for the charging of the situation.For
Special charging requirement under DC bus is shorted is adapted to, solves the problems, such as in charging process that half-bridge module fills and does not power on, and do not increase
Add new detection limit, a kind of new charging strategy need to be developed.
Summary of the invention
To solve the problem above-mentioned and defect, the object of the present invention is to provide a kind of flexible HVDC transmission system DC bus
Starting strategy in the case of short circuit determines that bridge arm is locking or excision by module voltage when DC bus is shorted
Module, make converter valve charged by lateral comparison and longitudinal comparison mode to module (calculate each bridge arm module voltage it
With lateral comparison is to all bridge arms, and longitudinal comparison is the upper and lower bridge arm to every phase), solve module charging problems, and by bridge
The difference control of module voltage in a certain range, avoids current measurement precision and dead zone from bringing walking direction is inaccurate to ask between arm
Topic.
In order to achieve the above object, the technical scheme adopted by the invention is as follows: a kind of flexible HVDC transmission system direct current is female
Starting strategy in the case of line short circuit, comprising the following steps:
Step 1, when DC bus is shorted, all module lockings, AC power source is by the soft resistance that opens to submodule progress
Uncontrollable rectifier charges, and after full-bridge modules voltage stabilization, full-bridge modules carry out self-test, and self-test passes through the then successful state of upload configuration
Information enters step 2；Fail self-test, then the status information of upload configuration failure, enters step 5；
Step 2, starting pressure algorithm is gone forward side by side line precharge, described to press algorithm method particularly includes: setting time-count cycle
Tset1, in each Tset1Incipient stage, by the average voltage V of half-bridge modules all in converter valveHWith setting value Uset1Compared
Compared with working as VH≥Uset1When, then enter step 3；Work as VH< Uset1When, then it is set by the result of lateral comparison and longitudinal comparison
Bridge arm is locking bridge arm or module excision bridge arm, and opening module controllably charges after setting, charges to time-count cycle
It is full, start next time-count cycle, until VH≥Uset1, enter step 3；
Step 3, all module self-tests, fail self-test, then the status information of upload configuration failure, enters step 5；Self-test is logical
The successful status information of then upload configuration is crossed, and starts pressure algorithm and carries out module charging；
It is described to press algorithm method particularly includes: setting T time-count cycleset2, in each Tset2Incipient stage, by the change of current
The average voltage U of all modules in valveSM-aveWith setting value Uset2It is compared, works as USM-ave≥Uset2When, then enter step 4；Such as
Fruit USM-ave< Uset2, then it is locking bridge arm or module excision that bridge arm is set by the result of lateral comparison and longitudinal comparison
Bridge arm, and opening module controllably charges after setting, charging to expires time-count cycle, start next time-count cycle, until
USM-ave≥Uset2, enter step 4；
Step 4, all module lockings, excision is soft to open resistance, starts successfully；
Step 5, all module lockings stop starting charging, starting failure；
In the step 2 and step 3,
The method of longitudinal comparison are as follows: by the sum of bridge arm module voltage V in every phasexP_sumThe sum of with lower bridge arm module voltage
VxN_sumIt is poor to make, and will make absolute value of the difference Δ VyWith limit value Ulim1It is compared, as Δ Vy≥Ulim1When, the phase module voltage it
It is latched with biggish bridge arm, the lesser bridge arm of the sum of module voltage cuts off N number of module, other module lockings；As Δ Vy< Ulim1
When, which is latched；
The method of lateral comparison are as follows: by the maximum value V of the sum of module voltage in all bridge armsmaxWith minimum value VminIt is poor to make,
And by difference DELTA VxWith limit value Ulim2It is compared, as Δ Vx< Ulim2When, module controllable aerating is carried out according to the result of longitudinal comparison
Electricity；As Δ Vx≥Ulim2When, VmaxThe upper and lower bridge arm of place phase is all latched, and then starting module controllably charges；
The Ulim1Limit value compared with indicating the sum of the sum of upper bridge arm module voltage of every phase and lower bridge arm module voltage,
Ulim2Indicate that the limit value in all bridge arms compared with the sum of the sum of module voltage maximum value and module voltage minimum value, x indicate a, b, c
Any one of three-phase；
The value of the N is as follows: [Ntol-Vline_pk/Urate/ 2] < N < NFB, wherein NtolFor bridge arm module number, Vline_pk
For valve side line voltage peak, UrateFor module voltage rating, NFBFor full-bridge modules number.
Further, described in step 2 in pressure algorithm, when carrying out lateral comparison and longitudinal comparison, when each phase
Δ VyRespectively less than Ulim1And Δ Vx< Ulim2When, system charged according to the charging modes in a upper time-count cycle；First
When secondary progress lateral comparison and longitudinal comparison, as the Δ V of each phaseyRespectively less than Ulim1And Δ Vx< Ulim2When, system is according to preparatory
The default value of setting is in T time-count cycleset1It is interior that module is pre-charged.
Further, the full-bridge modules self-test is to detect whether the full-bridge modules that draw-out power supply cannot be driven to work,
Self-test is normal to start by illustrating that full-bridge modules can drive draw-out power supply to work；Self-test does not pass through, and illustrates that presence cannot drive and takes
The full-bridge modules of energy power work, system do not allow to continue to start, maintenance down.
Further, longitudinal comparison described in step 2 and step 3 and lateral comparison are Dynamic comparison, the VxN_sum、
VxP_sum、VminAnd VmaxRecalculated in the incipient stage of each time-count cycle according to the charging result of upper a cycle.
Further, the setting value Uset1More than or equal to draw-out power supply operating voltage, it is less than module voltage rating；It is described
Setting value Uset2For module voltage rating.
Further, the Ulim1And Ulim2The adjustment of adaptability is carried out according to system voltage grade.
Further, Ulim1Take 2%~4%, U of single module voltage ratinglim2Modulus block voltage rating and number of modules product
2%.
Further, the Tset1And Tset2Value is identical.
Further, the Tset1And Tset2Value is 100 μ s.
Compared with prior art, the present invention at least has the following beneficial effects: starting strategy design of the invention rationally, institute
The detection limit being related to is module voltage, does not increase new detection limit, avoids current detection accuracy and direction is brought in dead zone
The inaccurate problem of judgement；Moreover, the present invention starts in strategy, module excision number N determines bridge arm half-bridge module and full-bridge modules
Equalizing effect, number of modules cut off number N it is very little, full-bridge modules charger can it is more, half-bridge module voltage cannot be charged to full-bridge modules
The consistent state of voltage；And module excision number N is when being more than full-bridge modules number, due in ranking results full-bridge modules voltage it is high and by
It takes the lead in cutting off, electric current flows through the bridge arm that half-bridge does not charge, and full-bridge and half-bridge will be caused not to charge, therefore need to select suitable mould
Block cuts off number, and direct current proposed by the present invention is shorted charging strategy and is directed to full-bridge half-bridge mixed connection flexible direct current system, the present invention
The value of middle N determines that method is the formula of [Ntol-Vline_pk/Urate/2] < N < NFB, and bridge arm full-bridge modules number NFB is needed
Greater than [Ntol-Vline_pk/Urate/2], the reliability and safety of charging are considered, if can choose in the enough situations of NFB
The excision number of modules that 1.1~1.2 times of voltage ratings need, i.e.,If the inadequate situation of NFB
Under, it can choose excision number N=NFB.
In addition, by adjusting Ulim1And Ulim2The difference of module voltage between bridge arm can be improved, it can be with by adjusting Ulim1
Improve the otherness between the upper and lower bridge arm of each phase, Ulim1 is smaller, and the frequency of upper and lower bridge arm switching charging is higher, and otherness is got over
It is small；By adjusting Ulim2The otherness of each alternate module voltage can be improved, theoretically Ulim2It is smaller, the difference of each alternate module
Property is smaller, but the difference frequency of the sum of the sum of module voltage maximum value and module voltage minimum value is numerous more than Ulim2Limit value, single-phase locking
Frequency increase, module charging rate is slack-off, is unfavorable for module instead and presses, therefore when debugging strategy, needs according to specific
The suitable U of system parameter selectionlim1And Ulim2。
The detection that the present invention does not depend on AC system voltage, alternating current, bridge arm current determines charge path, but logical
The mode for crossing detection module voltage sets charge path.
Detailed description of the invention
Fig. 1 is Booting sequence figure of the invention；
Fig. 2 is flexible HVDC transmission system converter valve topological diagram of the invention；
Fig. 3 is a certain charge path under present invention strategy；
Fig. 4 is another charge path under present invention strategy；
Fig. 5 is another charge path under present invention strategy；
Fig. 6 is another charge path under present invention strategy；
Fig. 7 is module capacitance voltage oscillogram of the invention.
Specific embodiment
Below in conjunction with drawings and the specific embodiments, specific embodiments of the present invention will be described in further detail.
Fig. 2 is flexible HVDC transmission system converter valve topological diagram provided in an embodiment of the present invention, and AC power source opens electricity through soft
Resistance, transformer and converter valve are attached, and converter valve includes six bridge arms, and each bridge arm is by several half-bridges and full-bridge modules group
At the DC bus end of converter valve is shorted.
Fig. 1 is Booting sequence figure of the invention, and the Booting sequence includes that step is implemented as follows:
Set T time-count cycleset1, in each Tset1Incipient stage, by the average voltage of half-bridge modules all in converter valve
VHWith setting value Uset1It is compared, until the average voltage V of all modulesHIt is all larger than setting value Uset1, precharge completion；
After the completion of precharge, T time-count cycle is setset2, in each Tset2Incipient stage, by modules all in converter valve
Average voltage USM-aveWith setting value Uset2It is compared, until the average voltage U of all modulesSM-aveIt is all larger than setting value
Uset2, charging complete.In the preferred embodiment of the present invention, Tset1And Tset2It is 100 μ s.
A, converter valve AC circuit breaker disconnects, and DC bus is shorted, soft to open resistance access, module locking；
B, converter valve AC circuit breaker be closed, AC power source by it is soft open resistance to submodule progress uncontrollable rectifier charging,
Since DC bus is shorted, current flowing branch is increased, with the circuit of converter valve composition, electric current is easier logical AC system
It crosses the lower branch of converter valve potential (half-bridge not charging paths) to flow through, half-bridge module charger can be less, and drive is not achieved and takes
The voltage of energy power work；
C, module voltage stablize after, full-bridge modules carry out self-test, upload configuration whether success command, unsuccessful, system is stopped
Machine cannot drive draw-out power supply to work, therefore without self-test since half-bridge module voltage is lower；
D, after full-bridge modules configuration successful, start to carry out for x phase (any phase of a/b/c), to calculate x phase from pressing
The sum of upper bridge arm module voltage VxP_sumAnd the sum of lower bridge arm module voltage VxN_sum, and find out module electricity in six bridge arms of converter valve
The sum of pressure maximum value VmaxAnd minimum value Vmin(or after the summation of every mutually all module voltages, then find out in three-phase maximum value and most
Small value, effect are not much different)；If VxP_sumSubtract VxN_sumIt is greater than the set value Ulim1When (Ulim1For controlling the difference between upper and lower bridge arm
Different, value is related to number of modules and module voltage rating, Ulim1Smaller, module voltage difference is smaller, but switches locking bridge arm frequency
Rate is higher, Ulim1Bigger, switching locking bridge arm frequency is lower, but module difference becomes larger), then bridge arm module is latched in x phase, x phase
Lower bridge arm module cuts off higher the module ([N of N number of voltage on demandtol-Vline_pk/Urate/ 2] < N < NFB, wherein NtolFor bridge
Arm number of modules, Vline_pkFor valve side line voltage peak, UrateFor module voltage rating, NFBFor full-bridge modules number), x phase lower bridge arm
The locking of other modules, increases x phase lower bridge arm module voltage, until VxN_sumSubtract VxP_sumIt is greater than the set value Ulim1When, switch to x
Phase lower bridge arm is latched, and bridge arm cuts off N number of higher module of voltage in x phase, and the locking of other modules of bridge arm, circuits sequentially in x phase；If
VmaxSubtract VminGreater than limit value Ulim2, wherein Ulim2For controlling each voltage between phases otherness, value and number of modules and the specified electricity of module
Pressure is related, Ulim2It is too small not powered on probably due to being mutually latched and frequently half-bridge being caused to fill, then regardless of VmaxThe upper bridge arm module of place phase
Whether the difference of the sum of voltage and the sum of lower bridge arm module voltage is more than limit value Ulim1, VmaxMutually upper and lower bridge arm is all latched at place,
The module of its bridge arm starts to charge；
In this way, carrying out cycle detection according to the time cycle of setting and comparing, half-bridge module voltage is begun to ramp up, will with this
Half-bridge module and full-bridge modules voltage are charged to consistent state；
E, when all half-bridge module average voltages reach setting value Uset1When, all module lockings, all modules start certainly
Inspection, upload configuration whether success command, the system-down if unsuccessful, wherein Uset1Greater than draw-out power supply operating voltage, it is less than
Module voltage rating；
F, after all module configuration successfuls, D step is repeated, until the average value of all module voltages reaches setting value
Uset2, and module is pressed and is all met the requirements, all modules are latched, wherein Uset2For module voltage rating；
G, excision is soft opens resistance, and start completion waits unlock.
By adjusting Ulim1And Ulim2The difference of module voltage between bridge arm can be improved.
Module excision number N determines the equalizing effect of bridge arm half-bridge module and full-bridge modules, and number of modules excision number N is very little,
Full-bridge modules charger can be more, and half-bridge module voltage cannot be charged to the consistent state of full-bridge modules voltage；And module excision number N is super
When crossing full-bridge modules number, taken the lead in cutting off due to full-bridge modules voltage height in ranking results, electric current flows through what half-bridge did not charged
Bridge arm will cause full-bridge and half-bridge not to charge, therefore need to select suitable module excision number.
Above-mentioned detection limit is module voltage, does not increase new detection limit, avoids current detection accuracy and dead zone is brought
The inaccurate problem of walking direction.
Fig. 3 gives the charge path 1 formed according to starting strategy, by taking a, b phase as an example, if a phase alternating voltage is higher than b
Phase, when a, b phase lower bridge arm are latched, bridge arm cuts off N number of module respectively in a, b phase, then alternating current is flowed into from bridge arm in a phase, from b
Bridge arm flows out in phase.
Fig. 4 gives the charge path 2 formed according to starting strategy, by taking a, b phase as an example, if a phase alternating voltage is higher than b
Phase, when bridge arm is latched in a, b phase, a, b phase lower bridge arm cut off N number of module, then alternating current is flowed into from a phase lower bridge arm, under b phase
Bridge arm outflow.
Fig. 5 gives the charge path 3 formed according to starting strategy, by taking a, b phase as an example, if a phase alternating voltage is higher than b
Phase, when bridge arm is latched in a phase, a phase lower bridge arm cuts off N number of module, and b phase lower bridge arm is latched, and bridge arm cuts off N number of module in b phase, then
Alternating current is flowed into from a phase lower bridge arm, is flowed out by DC bus from bridge arm in b phase.
Fig. 6 gives the charge path 4 formed according to starting strategy, by taking a, b phase as an example, if a phase alternating voltage is higher than b
Phase, when a phase lower bridge arm is latched, bridge arm cuts off N number of module in a phase, and bridge arm locking in b phase, b phase lower bridge arm cuts off N number of module, then
Alternating current is flowed into from bridge arm in a phase, is flowed out by DC bus from b phase lower bridge arm.
Fig. 7 gives the half-bridge obtained according to designed Booting sequence and full-bridge modules capacitance voltage waveform.According to institute
The Booting sequence of design, each stage timing are as follows:
(1) t0~t1 opens the charging of resistance uncontrollable rectifier with soft, and full-bridge modules self-test after module voltage is stablized concurrently configures
Order；
(2) t1~t2, algorithm is pressed in starting, when half-bridge module voltage rises to Uset1When, all module lockings；
(3) t2~t3, all module self-tests, concurrent configuration order；
(4) t3~t4, algorithm is pressed in starting, when module average voltage rises to Uset2When, all module lockings；
(5) t4~t5 opens resistance self discharge with soft；
(6) t5~t6 is soft to open resistance excision, start completion, into waiting unlocked state.
Finally it should be noted that those of ordinary skills in the art should understand that arrive: those skilled in the art can be with
Modifications or equivalent substitutions are made to specific embodiments of the invention, but these modifications or change are applying for pending right
Among claimed range.
Claims (9)
1. the starting strategy in the case of a kind of flexible HVDC transmission system DC bus short circuit, which is characterized in that including following step
It is rapid:
Step 1, when DC bus is shorted, all modules locking, AC power source is opened resistance and is not controlled to submodule by soft
Rectification charging, after full-bridge modules voltage stabilization, full-bridge modules carry out self-test, and self-test passes through the successful state letter of then upload configuration
Breath, enters step 2；Fail self-test, then the status information of upload configuration failure, enters step 5；
Step 2, starting pressure algorithm is gone forward side by side line precharge, described to press algorithm method particularly includes: setting T time-count cycleset1,
In each Tset1Incipient stage, by the average voltage V of half-bridge modules all in converter valveHWith setting value Uset1It is compared, when
VH≥Uset1When, then enter step 3；Work as VH< Uset1When, then bridge arm is set by the result of lateral comparison and longitudinal comparison is
It is latched bridge arm or module cuts off bridge arm, and opening module controllably charges after setting, charging to expires time-count cycle, starts
Next time-count cycle, until VH≥Uset1, enter step 3；
Step 3, all module self-tests, fail self-test, then the status information of upload configuration failure, enters step 5；Self-test is by then
The successful status information of upload configuration, and start pressure algorithm and carry out module charging；
It is described to press algorithm method particularly includes: setting T time-count cycleset2, in each Tset2Incipient stage, will be in converter valve
The average voltage U of all modulesSM-aveWith setting value Uset2It is compared, works as USM-ave≥Uset2When, then enter step 4；If
USM-ave< Uset2, then it is locking bridge arm or module excision bridge that bridge arm is set by the result of lateral comparison and longitudinal comparison
Arm, and opening module controllably charges after setting, charging to expires time-count cycle, start next time-count cycle, until
USM-ave≥Uset2, enter step 4；
Step 4, all module lockings, excision is soft to open resistance, starts successfully；
Step 5, all module lockings stop starting charging, starting failure；
In the step 2 and step 3,
The method of longitudinal comparison are as follows: by the sum of bridge arm module voltage V in every phasexP_sumWith the sum of lower bridge arm module voltage VxN_sumMake
Difference, and absolute value of the difference Δ V will be madeyWith limit value Ulim1It is compared, as Δ Vy≥Ulim1When, the sum of the phase module voltage is larger
Bridge arm locking, the lesser bridge arm of the sum of module voltage cuts off N number of module, other modules lockings；As Δ Vy< Ulim1When, the phase
Upper and lower bridge arm is latched；
The method of lateral comparison are as follows: by the maximum value V of the sum of module voltage in all bridge armsmaxWith minimum value VminIt is poor to make, and will
Difference DELTA VxWith limit value Ulim2It is compared, as Δ Vx< Ulim2When, module is carried out according to the result of longitudinal comparison and is controllably charged；
As Δ Vx≥Ulim2When, VmaxThe upper and lower bridge arm of place phase is all latched, and then starting module controllably charges；
The Ulim1Limit value compared with indicating the sum of the sum of upper bridge arm module voltage of every phase and lower bridge arm module voltage, Ulim2Table
Show the limit value in all bridge arms compared with the sum of the sum of module voltage maximum value and module voltage minimum value, x indicates a, b, in c three-phase
Any one；
The value of the N is as follows: [Ntol-Vline_pk/Urate/ 2] < N < NFB, wherein NtolFor bridge arm module number, Vline_pkFor valve
Side line voltage peak, UrateFor module voltage rating, NFBFor full-bridge modules number.
2. the starting strategy in the case of a kind of flexible HVDC transmission system DC bus short circuit as described in claim 1, special
Sign is, described in step 2 in pressure algorithm, when carrying out lateral comparison and longitudinal comparison, as the Δ V of each phaseyIt is small
In Ulim1And Δ Vx< Ulim2When, system charged according to the charging modes in a upper time-count cycle；It is carried out laterally in first time
When comparing with longitudinal comparison, as the Δ V of each phaseyRespectively less than Ulim1And Δ Vx< Ulim2When, system is according to pre-set default
Value is in T time-count cycleset1It is interior that module is pre-charged.
3. the starting strategy in the case of a kind of flexible HVDC transmission system DC bus short circuit as described in claim 1, special
Sign is that the full-bridge modules self-test is to detect whether the full-bridge modules that draw-out power supply cannot be driven to work, and self-test passes through
Bright full-bridge modules can drive draw-out power supply to work, normal to start；Self-test does not pass through, and illustrates that presence cannot drive draw-out power supply to work
Full-bridge modules, system do not allow to continue to start, maintenance down.
4. the starting strategy in the case of a kind of flexible HVDC transmission system DC bus short circuit as described in claim 1, special
Sign is that longitudinal comparison described in step 2 and step 3 and lateral comparison are Dynamic comparison, the VxN_sum、VxP_sum、VminAnd
VmaxRecalculated in the incipient stage of each time-count cycle according to the charging result of upper a cycle.
5. the starting strategy in the case of a kind of flexible HVDC transmission system DC bus short circuit as described in claim 1, special
Sign is, the setting value Uset1More than or equal to draw-out power supply operating voltage, it is less than module voltage rating；The setting value Uset2
For module voltage rating.
6. the starting strategy in the case of a kind of flexible HVDC transmission system DC bus short circuit as described in claim 1, special
Sign is, the Ulim1And Ulim2The adjustment of adaptability is carried out according to system voltage grade.
7. the starting strategy in the case of a kind of flexible HVDC transmission system DC bus short circuit as claimed in claim 6, special
Sign is, Ulim1Take 2%~4%, U of single module voltage ratinglim2The 2% of modulus block voltage rating and number of modules product.
8. the starting strategy in the case of a kind of flexible HVDC transmission system DC bus short circuit as described in claim 1, special
Sign is, the Tset1And Tset2Value is identical.
9. the starting strategy in the case of a kind of flexible HVDC transmission system DC bus short circuit as described in claim 1, special
Sign is, the Tset1And Tset2Value is 100 μ s.
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