CN104753043B - Multi-level current converter with direct-current fault ride-through capability and working method - Google Patents
Multi-level current converter with direct-current fault ride-through capability and working method Download PDFInfo
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Abstract
The invention discloses a mixed type multi-level current converter with direct-current fault ride-through capability and a working method. The current converter is based on a dislocation stacking theory and comprises a three-phase bridge rectifier circuit; each bridge arm of the three-phase bridge rectifier circuit comprises a dislocation stacking module, a cascading double-sub-module assembly, a half-bridge sub-module assembly and an electric reactor which are cascaded to one another; when a fault occurs, a discharging process before locking of the current converter is an oscillating discharging process under known initial conditions; and after the current converter is locked, equivalent capacitance values of the bridge arms are changed, if and only if backward voltages of cascading capacitors of the bridge arms are always greater than an alternating-current line voltage amplitude value in any loop states, a short-circuiting current is reduced to zero by the inverting blocking characteristic of diodes, and the direct-current fault is eliminated. The direct-current fault is eliminated in a self-limited manner by locking the current converter, and an extra high-voltage and direct-current circuit breaker is not required. The mixed type multi-level current converter with the direct-current fault ride-through capability is suitable for a common overhead circuit, and can be used for the fields of multi-terminal direct-current network establishment, new energy grid connection, passive network power supply and the like.
Description
Technical field
The present invention relates to power system technical field of electric power transmission, and in particular to a kind of mixing with DC Line Fault ride-through capability
Type multilevel converter and method of work.
Background technology
With developing rapidly for Power Electronic Technique, the voltage source converter (Voltage based on full-control type semiconductor device
Source Converter, VSC) high-voltage dc transmission electrical domain has been applied to more and more.Compared to Traditional DC transmission of electricity,
Flexible DC power transmission (VSC-HVDC) based on VSC has that through-put power is flexibly controllable, can compensate for no-power vacancy, can be to passive
The advantages of network power supply, easy composition multiterminal network.According to the difference of converter structure, flexible DC power transmission can be divided into low level
The VSC-HVDC and MMC-HVDC based on modularization multi-level converter (Modular Multilevel Converter, MMC).
The latter compared to the former have switching frequency it is low, be lost little, modular construction be easy to extension, to devices switch coherence request not
It is high, suitable for high voltage occasion the advantages of, thus developed rapidly in recent years.
According to the difference for constituting sub-modular structure, generally can be by MMC point：Semi-bridge type MMC (Half Bridge MMC,
FBMMC), bridge-type MMC (Full Bridge MMC, FBMMC) and double Clamp MMC (Clamp Double MMC,
CDMMC) etc..Study at present more and put into operation or in the flexible direct current power transmission system built (such as the end flexible direct current work of Nan'ao three
Journey, the end flexible direct current engineering of Zhoushan five) adopt semi-bridge type MMC structures.However, the characteristics of semi-bridge type MMC is due to self structure,
Short circuit current cannot be cut off by controlling the locking of inverter when DC side breaks down, can only be cut-off by AC circuit breaker
Whole straight-flow system, this seriously increased the fault clearance time, reduces power supply reliability.
To reduce impact of the DC Line Fault to transmission system, at present adoptable method includes：Install HVDC open circuit additional
Device, the FBMMC or CDMMC as transmission line, employing using the relatively low cable of fault rate with DC Line Fault ride-through capability.But
Suffer from the drawback that：The too high shortage economy of high-power dc circuit breaker also immature and price in engineer applied；Electricity
Cable Transmission Cost is higher and is easily restricted by laying environment；FBMMC or CDMMC itself has removing DC Line Fault ability,
But required semiconductor device quantity is multiplied, and lacks economy and practicality.
The content of the invention
To solve the deficiency that prior art is present, the invention discloses how electric the mixed type with DC Line Fault ride-through capability is
Flat inverter and method of work, the present invention can remove direct fault current, and required semiconductor device by locking inverter
Quantity is few, and output voltage waveforms quality is high during normal operation, with preferable economy and practicality.
For achieving the above object, concrete scheme of the invention is as follows：
A kind of multilevel converter with DC Line Fault ride-through capability, including three-phase bridge rectifier circuit；The three-phase
Each bridge arm of bridge rectifier includes dislocation layered module, cascade Shuangzi module group, the semi-bridge type submodule being in series
Group and reactor；The dislocation layered module, cascade Shuangzi module group, the structure that semi-bridge type submodule group is mutual cascade；
The discharge process when failure occurs before converter blocking is the oscillating discharge process of a known initial condition, after locking by
Change in bridge arm equivalent capacitance, the backward voltage that bridge arm cascade electric capacity is provided under and if only if any loop state begins
When eventually more than ac line voltage amplitude, make short circuit current drop to zero using the anti-phase blocking characteristics of diode, remove DC Line Fault.
The dislocation layered module is in series by m half-bridge cells；Each half-bridge cells is first including 2 IGBT
IGBT and the 2nd IGBT, 2 backward diodes and 1 capacitor；2 IGBT respectively with corresponding 2 reverse two poles
Pipe composes in parallel 2 groups of gate-controlled switches；The emitter stage of the first IGBT and the colelctor electrode of the 2nd IGBT are connected；The positive pole of capacitor and
The colelctor electrode of one IGBT is connected, and the emitter stage of the negative pole of capacitor and the 2nd IGBT is connected.
The cascade Shuangzi module group is by nSIndividual cascade Shuangzi block coupled in series is constituted；Each cascade Shuangzi module includes 5
IGBT is T1~T5, 5 backward diodes be D1~D5, 2 capacitors be C1~C2And 1 clamp diode D6；Described 5
IGBT composes in parallel 5 groups of gate-controlled switches with corresponding 5 backward diodes respectively；The T1Emitter stage and T2Colelctor electrode phase
Even, T3Emitter stage and T4Colelctor electrode be connected, T2Emitter stage and T5Emitter stage be connected, T3Colelctor electrode and T5Colelctor electrode
It is connected；The capacitor C1Positive pole respectively with T1Colelctor electrode, diode D6Negative pole be connected, capacitor C1Negative pole and T2's
Emitter stage is connected；The capacitor C2Negative pole respectively with T4Emitter stage, diode D6Positive pole be connected, capacitor C2Just
Pole and T3Colelctor electrode be connected.
The semi-bridge type submodule group is by nHIndividual semi-bridge type submodule is in series；Each semi-bridge type submodule includes 2
IGBT is the 3rd IGBT and the 4th IGBT, 2 backward diodes and 1 capacitor；2 IGBT are respectively and accordingly
2 backward diodes compose in parallel 2 groups of gate-controlled switches；The emitter stage of the 3rd IGBT and the colelctor electrode of the 4th IGBT are connected；
The colelctor electrode of the positive pole of the capacitor and the 3rd IGBT is connected, and the emitter stage of the negative pole of capacitor and the 4th IGBT is connected.
Number m of half-bridge cells meets relationship below in the dislocation layered module：
Wherein：UcFor the rated capacity voltage in semi-bridge type submodule, UmcFor the rated capacity voltage in half-bridge cells.
Number n of the cascade Shuangzi module group cascade Shuangzi moduleSMeet relationship below：
Wherein：UmFor the maximum of inverter AC phase voltage, Uc1Rated capacity voltage in cascade Shuangzi module.
Number n of semi-bridge type submodule in the semi-bridge type submodule groupHMeet relationship below：
Wherein：UdcFor the rated direct voltage of DC power transmission line, UcFor the rated capacity voltage in semi-bridge type submodule.
The exportable overall level number N of the mixed type multilevel converterPMeet relationship below：
NP=(nH+2nS+1)×(m+1)。
The method of work of the mixed type multilevel converter with DC Line Fault ride-through capability, comprises the following steps：
Step (1)：Voltage and current on current conversion station real-time monitoring DC line, with reference to DC transmission system parameter, if
Fixed corresponding failure determination threshold value, completes the determination to DC line fault moment and fault type；
Step (2)：DC transmission system detect DC Line Fault occur after, according to current conversion station DC side exit electric current,
The change of voltage and direction of tide determine the position of fault, and the disconnecting switch on incipient fault circuit is marked, so as to
Faulty line after locking is reliably isolated；
Step (3)：Block signal is sent to the cascade Shuangzi module in mixed type multilevel converter, half-bridge is closed at
Type submodule and dislocation layered module by-pass switch each in parallel, in protecting semi-bridge type submodule and dislocation layered module
Semiconductor device is not damaged by overcurrent, and the time used by this process should include the dynamic of the time delay of failure detector and protection device
Make the time；
Step (4)：Locking finishes the disconnecting switch of labelling in rear break step (2), to guarantee that fault current is completely eliminated,
The moment for disconnecting disconnecting switch need to be set according to the blocking time of inverter；
Step (5)：Whole current conversion stations are sent with unlocking signal, setting current conversion station operates in constant DC voltage control mode
Under, DC bus-bar voltage rises to rated value, and now the disconnecting switch in step (4) on the non-fault line of tripping can be felt
The default DC voltage in two ends should be arrived, " shaking hands " disconnecting switch closure afterwards is realized when both end voltage difference is met less than setting value,
Again current conversion station is set into back the respective method of operation after non-fault line disconnecting switch closure, isolate so as to complete faulty line,
Non-fault line resumes operation, and whole system is issued to a new steady s tate in default service condition.
Beneficial effects of the present invention：
1. the mixed type multilevel converter of the present invention is theoretical based on dislocation stacking, double using dislocation layered module, cascade
The structure that submodule, semi-bridge type submodule are mutually cascaded, makes with optimization output level, reduction harmonic content, semiconductor device
The advantages of with quantity less.
2. the mixed type multilevel converter of the present invention, when DC side is short-circuited failure, can pass through the locking change of current
Device, without the need for optional equipment high voltage DC breaker, it is adaptable to common overhead transmission line, can be applied from removing direct fault current is limited
The field such as power in multiterminal element network struction, new-energy grid-connected, passive network.
3. the mixed type multilevel converter of the present invention, has that semi-bridge type MMC is economic, practical, control plan during normal operation
The advantages of slightly simple, control method is ripe, is provided simultaneously with the ability of self-cleaning DC Line Fault, for raising MTDC transmission system
Stability has certain Research Significance.
Description of the drawings
Fig. 1 is mixed type multilevel converter structural representation of the present invention with DC Line Fault ride-through capability；
Inverter schematic equivalent circuit when Fig. 2 is DC Line Fault；
The equivalent circuit diagram of semi-bridge type submodule blocking when Fig. 3 (a) is flowed to for forward current；
The equivalent circuit diagram of semi-bridge type submodule blocking when Fig. 3 (b) is flowed to for negative current；
The equivalent circuit diagram of bridge-type submodule blocking when Fig. 3 (c) is flowed to for forward current；
The equivalent circuit diagram of bridge-type submodule blocking when Fig. 3 (d) is flowed to for negative current；
The equivalent circuit diagram of Shuangzi module blocking is clamped when Fig. 3 (e) is flowed to for forward current；
The equivalent circuit diagram of Shuangzi module blocking is clamped when Fig. 3 (f) is flowed to for negative current；
The equivalent circuit diagram of Shuangzi module blocking is cascaded when Fig. 3 (g) is flowed to for forward current；
The equivalent circuit diagram of Shuangzi module blocking is cascaded when Fig. 3 (h) is flowed to for negative current；
Fig. 4 is inverter output voltage waveform diagram after addition dislocation layered module；
Fig. 5 is typical four ends flexible direct current power transmission system structural representation；
Fig. 6 (a) active power waveform diagrams under DC Line Fault for the present invention；
Fig. 6 (b) reactive power waveform diagrams under DC Line Fault for the present invention；
Fig. 6 (c) trouble point DC voltage waveform schematic diagrams under DC Line Fault for the present invention；
Fig. 6 (d) trouble point dc current waveform schematic diagrams under DC Line Fault for the present invention；
Fig. 6 (e) bridge arm submodule capacitor voltage waveform diagrams in a phases under DC Line Fault for the present invention；
Fig. 6 (f) inverter AC voltage waveform views under DC Line Fault for the present invention；
Fig. 6 (g) inverter ac-side current waveform diagrams under DC Line Fault for the present invention.
Specific embodiment：
Below in conjunction with the accompanying drawings the present invention is described in detail：
As shown in figure 1, a kind of mixed type multilevel converter with DC Line Fault ride-through capability, including three-phase bridge is whole
Current circuit；Each bridge arm of three-phase bridge rectifier circuit is by the layered module that misplaces, cascade Shuangzi module group, semi-bridge type submodule group
And reactor is in series.
As shown in Fig. 2 the submodule of each bridge arm cascade of inverter is equivalent with ideal voltage source, wherein：L is bridge arm electricity
Sense, R be bridge arm substitutional resistance, LTFor converter power transformer leakage inductance, uabcAnd iabcThe respectively voltage and electricity of converter power transformer net side
Stream, LdcAnd RdcRespectively DC line equivalent inductance and resistance, RfFor fault resstance.
Upper and lower bridge arm application Kirchhoff's second law can be obtained：
Upper and lower bridge arm application Kirchhoff's current law (KCL) can be obtained：
ik=ikn-ikp
DC voltage, electric current meet respectively：
Wherein：CeqFor fault moment bridge arm equivalent capacitance.
Various simultaneous can be obtained by more than：
Wherein：Le=2L/3+Ldc；Re=2R/3+Rdc+Rf；Ce=3Ceq。
There is the moment as t=0 with failure, Udc、IdcFor initial value, solving equation can obtain DC current idcAnalytical expression
For：
Wherein：τ=2Le/Re；α=arctan (ω
τ)。
Failure occur when converter blocking before discharge process be a known initial condition oscillating discharge process, locking
Afterwards because bridge arm equivalent capacitance changes, the reverse electricity that bridge arm cascade electric capacity is provided under and if only if any loop state
When pressure is consistently greater than ac line voltage amplitude, using the anti-phase blocking characteristics of diode short circuit current can be made to drop to zero, so as to clear
Except DC Line Fault.
As shown in Fig. 3 (a), (b), semi-bridge type submodule blocking equivalent voltage is U when forward current is flowed toc, negative sense
Equivalent voltage is 0 during current direction, and backward diode can provide path for fault current, therefore cannot remove DC Line Fault；Such as
Shown in Fig. 3 (c), (d), bridge-type submodule blocking equivalent voltage is U when forward current is flowed toc, when negative current is flowed to
Equivalent voltage is also Uc, using the anti-phase blocking characteristics of diode short circuit current can be made to drop to zero, so as to remove DC Line Fault；Such as
Shown in Fig. 3 (e), (f), it is 2U that Shuangzi module blocking equivalent voltage is clamped when forward current is flowed toc, when negative current is flowed to
Equivalent voltage is Uc, because equivalent circuit has two kinds of different conditions, system antithetical phrase module capacitance charges repeatedly, causes direct current event
Barrier checkout time extends；As shown in Fig. 3 (g), (h), Shuangzi module blocking equivalent voltage is cascaded when forward current is flowed to is
2Uc, equivalent voltage is also 2U when negative current is flowed toc, externally equivalent circuit state is constant during failure, and produces specific equivalent
Quasiconductor negligible amounts needed for voltage, fault clearance effect and economy it is all good.
Dislocation layered module is in series by m half-bridge cells, using upper and lower bridge arm symmetrical structure, can be in former output
Some dislocation by a small margin are produced on the basis of voltage waveform, then the dislocation waveform of different amplitudes is overlapped, be just obtained
The voltage waveform that one level number is higher, harmonic content is less.As shown in figure 4, work as half-bridge cells number m in dislocation layered module being
When 2, the voltage waveform that a level number is 2 can be improved into the voltage waveform that level number is 7, so as to obtain higher fitting
Degree.
When DC side occurs permanent bipolar short trouble, system realizes that faulty line excision, non-fault line recover
Process is comprised the following steps that：
Step (1)：Voltage and current on current conversion station real-time monitoring DC line, with reference to DC transmission system parameter, if
Fixed corresponding failure determination threshold value, completes the determination to DC line fault moment and fault type；
Step (2)：DC transmission system detect DC Line Fault occur after, according to current conversion station DC side exit electric current,
The change of voltage and direction of tide determine the position of fault, and the disconnecting switch on incipient fault circuit is marked, so as to
Faulty line after locking is reliably isolated；
Step (3)：Block signal is sent to the cascade Shuangzi module in mixed type multilevel converter, half-bridge is closed at
Type submodule and dislocation layered module by-pass switch each in parallel, in protecting semi-bridge type submodule and dislocation layered module
Semiconductor device is not damaged by overcurrent, and the time used by this process should include the dynamic of the time delay of failure detector and protection device
Make the time；
Step (4)：Locking finishes the disconnecting switch of labelling in rear break step (2), to guarantee that fault current is completely eliminated,
The moment for disconnecting disconnecting switch need to be set according to the blocking time of inverter；
Step (5)：Whole current conversion stations are sent with unlocking signal, setting current conversion station operates in constant DC voltage control mode
Under, DC bus-bar voltage rises to rated value, and now the disconnecting switch in step (4) on the non-fault line of tripping can be felt
The default DC voltage in two ends should be arrived, " shaking hands " disconnecting switch closure afterwards is realized when both end voltage difference is met less than setting value,
Again current conversion station is set into back the respective method of operation after non-fault line disconnecting switch closure, isolate so as to complete faulty line,
Non-fault line resumes operation, and whole system is issued to a new steady s tate in default service condition.
In order to further verify the effectiveness and feasibility of present embodiment, in power system transient simulation software PSCAD/
The end flexible direct current power transmission system of typical case four as shown in Figure 5 is built in EMTDC, design parameter is：AC system electric pressure
220kV；Straight-flow system electric pressure ± 200kV；Converter power transformer adopts Y0/ △ type the modes of connection, leakage reactance 0.1pu；Current conversion station
Each bridge arm is formed by 12 HBSM, 4 SDSM and 1 MCSM cascades, and capacity is 400MVA；The μ F of submodule electric capacity 3400；Often
Bridge arm current-limiting reactor 32mH；MMC1 is adopted and is determined DC voltage and determine the control mode of alternating voltage, and MMC2 adopts DC voltage
Decline and determine the control mode of alternating voltage, MMC3 and MMC4 is adopted and determined active power and determine the control mode of reactive power；
Connected by direct current cables between current conversion station, set the unit distance impedance of cable as 0.01 Ω/km, each segment length l12、l23、
l34、l14Respectively 100km, 120km, 200km, 180km.
When assuming that systematic steady state is run to 2s, in DC line l12There is DC side near the port of current conversion station 1 bipolar
Short trouble.Fig. 6 (a) is active power waveform diagram under DC Line Fault；Fig. 6 (b) is reactive power waveform under DC Line Fault
Schematic diagram；Fig. 6 (c) is trouble point DC voltage waveform schematic diagram under DC Line Fault；Fig. 6 (d) is that trouble point is straight under DC Line Fault
Stream current waveform schematic diagram；Fig. 6 (e) is bridge arm submodule capacitor voltage waveform diagram in a phases under DC Line Fault；Fig. 6 (f) is
Inverter AC voltage waveform view under DC Line Fault；Fig. 6 (g) is that inverter ac-side current waveform shows under DC Line Fault
It is intended to.
From the point of view of above-mentioned figure, present embodiment has the quick lock inverter when there is DC Line Fault, and in the short time
It is interior to recover the ability that non-fault line normally runs；Submodule capacitor voltage is maintained near rated value and protected during failure locking
Hold constant, submodule can be direct plungeed into using without the need for recharged after faulty line excision, shorten system resumes power institute
Take time；There is not the out-of-limit situation of alternating current in idle interval, and alternating voltage change is maintained within ± 5%, to exchange
The impact of system is less.
Although the above-mentioned accompanying drawing that combines is described to the specific embodiment of the present invention, not to present invention protection model
The restriction enclosed, one of ordinary skill in the art should be understood that on the basis of technical scheme those skilled in the art are not
Need the various modifications made by paying creative work or deformation still within protection scope of the present invention.
Claims (9)
1. a kind of multilevel converter with DC Line Fault ride-through capability, is characterized in that, including three-phase bridge rectifier circuit；Institute
State dislocation layered module, cascade Shuangzi module group, semi-bridge type that each bridge arm of three-phase bridge rectifier circuit includes being in series
Submodule group and reactor；The dislocation layered module, cascade Shuangzi module group, semi-bridge type submodule group are mutual cascade
Structure；The discharge process when failure occurs before converter blocking is the oscillating discharge process of a known initial condition, is closed
Because bridge arm equivalent capacitance changes after lock, under and if only if any loop state bridge arm cascade electric capacity provided it is reverse
When voltage is consistently greater than ac line voltage amplitude, make short circuit current drop to zero using the anti-phase blocking characteristics of diode, remove straight
Stream failure.
2. a kind of multilevel converter with DC Line Fault ride-through capability as claimed in claim 1, is characterized in that, the mistake
Position layered module is in series by m half-bridge cells；Each half-bridge cells include 2 IGBT be an IGBT and the 2nd IGBT, 2
Individual backward diode and 1 capacitor；2 IGBT compose in parallel with corresponding 2 backward diodes respectively 2 groups it is controllable
Switch；The emitter stage of the first IGBT and the colelctor electrode of the 2nd IGBT are connected；The colelctor electrode phase of the positive pole of capacitor and an IGBT
Even, the emitter stage of the negative pole of capacitor and the 2nd IGBT is connected.
3. a kind of multilevel converter with DC Line Fault ride-through capability as claimed in claim 1, is characterized in that, the level
Connection Shuangzi module group is by nSIndividual cascade Shuangzi block coupled in series is constituted；Each cascade Shuangzi module is T including 5 IGBT1~T5, 5
Backward diode is D1~D5, 2 capacitors be C1~C2And 1 clamp diode D6；5 IGBT are respectively and accordingly
5 backward diodes compose in parallel 5 groups of gate-controlled switches；The T1Emitter stage and T2Colelctor electrode be connected, T3Emitter stage and T4
Colelctor electrode be connected, T2Emitter stage and T5Emitter stage be connected, T3Colelctor electrode and T5Colelctor electrode be connected；The capacitor C1
Positive pole respectively with T1Colelctor electrode, diode D6Negative pole be connected, capacitor C1Negative pole and T2Emitter stage be connected；It is described
Capacitor C2Negative pole respectively with T4Emitter stage, diode D6Positive pole be connected, capacitor C2Positive pole and T3Colelctor electrode phase
Even.
4. a kind of multilevel converter with DC Line Fault ride-through capability as claimed in claim 1, is characterized in that, described half
Bridge type submodule group is by nHIndividual semi-bridge type submodule is in series；Each semi-bridge type submodule include 2 IGBT be the 3rd IGBT and
4th IGBT, 2 backward diodes and 1 capacitor；2 IGBT respectively with corresponding 2 backward diode parallel connections
Constitute 2 groups of gate-controlled switches；The emitter stage of the 3rd IGBT and the colelctor electrode of the 4th IGBT are connected；The positive pole of the capacitor and
The colelctor electrode of the 3rd IGBT is connected, and the emitter stage of the negative pole of capacitor and the 4th IGBT is connected.
5. a kind of multilevel converter with DC Line Fault ride-through capability as claimed in claim 2, is characterized in that, the mistake
Number m of half-bridge cells meets relationship below in the layered module of position：
Wherein：UcFor the rated capacity voltage in semi-bridge type submodule, UmcFor the rated capacity voltage in half-bridge cells.
6. a kind of multilevel converter with DC Line Fault ride-through capability as claimed in claim 5, is characterized in that, the level
Number n of connection Shuangzi module group cascade Shuangzi moduleSMeet relationship below：
Wherein：UmFor the maximum of inverter AC phase voltage, Uc1Rated capacity voltage in cascade Shuangzi module.
7. a kind of multilevel converter with DC Line Fault ride-through capability as claimed in claim 6, is characterized in that, described half
Number n of semi-bridge type submodule in bridge type submodule groupHMeet relationship below：
Wherein：UdcFor the rated direct voltage of DC power transmission line, UcFor the rated capacity voltage in semi-bridge type submodule, nSFor
The number of cascade Shuangzi module group cascade Shuangzi module.
8. a kind of multilevel converter with DC Line Fault ride-through capability as claimed in claim 7, is characterized in that, described many
The exportable overall level number N of level converterPMeet relationship below：
NP=(nH+2nS+1)×(m+1)
nHFor the number of semi-bridge type submodule in semi-bridge type submodule group, nSTo cascade Shuangzi module group cascade Shuangzi module
Number.
9. a kind of method of work of the multilevel converter with DC Line Fault ride-through capability as claimed in claim 1, it is special
Levying is, comprises the following steps：
Step (1)：Voltage and current on current conversion station real-time monitoring DC line, with reference to DC transmission system parameter, sets phase
The failure determination threshold value answered, completes the determination to DC line fault moment and fault type；
Step (2)：DC transmission system is detected after DC Line Fault generation, according to current conversion station DC side exit electric current, voltage
Change and direction of tide determine the position of fault, and the disconnecting switch on incipient fault circuit is marked, so as to closing
Faulty line after lock is reliably isolated；
Step (3)：Block signal is sent to the cascade Shuangzi module in mixed type multilevel converter, semi-bridge type is closed at
Module and dislocation layered module by-pass switch each in parallel, with partly leading in protecting semi-bridge type submodule and dislocation layered module
Body device is not damaged by overcurrent, when the time used by this process should include the time delay of failure detector and the action of protection device
Between；
Step (4)：Locking finishes the disconnecting switch of labelling in rear break step (2), to guarantee that fault current is completely eliminated, needs root
The moment of disconnecting switch is disconnected according to the blocking time setting of inverter；
Step (5)：Whole current conversion stations are sent with unlocking signal, setting current conversion station is operated under constant DC voltage control mode, directly
Stream busbar voltage rises to rated value, and now the disconnecting switch in step (4) on the non-fault line of tripping can be sensed
The default DC voltage in two ends, " shaking hands " disconnecting switch closure afterwards, non-event are realized when both end voltage difference is met less than setting value
Again current conversion station is set into back the respective method of operation after barrier line disconnecting switch closure, so as to complete faulty line isolation, non-event
Barrier circuit resumes operation, and whole system is issued to a new steady s tate in default service condition.
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| CN201510141886.6A CN104753043B (en) | 2015-03-27 | 2015-03-27 | Multi-level current converter with direct-current fault ride-through capability and working method |
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| CN201510141886.6A CN104753043B (en) | 2015-03-27 | 2015-03-27 | Multi-level current converter with direct-current fault ride-through capability and working method |
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| CN108134384B (en) * | 2017-12-28 | 2020-06-02 | 清华大学 | Staggered connection soft switch hybrid multi-level direct current interconnected converter |
| CN108429252B (en) * | 2018-02-08 | 2020-12-04 | 中国科学院电工研究所 | Method for calculating contribution short-circuit current of alternating current system during direct current fault of multi-terminal alternating current-direct current hybrid power distribution network |
| CN109638789B (en) * | 2018-10-29 | 2020-07-07 | 全球能源互联网研究院有限公司 | Direct-current bipolar short-circuit fault protection method and device of flexible alternating-current and direct-current interconnection system |
| CN109861192B (en) * | 2018-12-17 | 2020-05-19 | 华中科技大学 | Method for restraining direct-current fault current of flexible direct-current converter and application of method |
| CN110995039B (en) * | 2019-11-25 | 2020-11-24 | 上海交通大学 | Low-loss modular multilevel converter and parameter design method thereof |
| CN111181416B (en) * | 2020-01-09 | 2021-03-19 | 华北电力大学 | Modular multilevel converter and direct-current fault clearing method |
| CN111200366A (en) * | 2020-01-15 | 2020-05-26 | 西安交通大学 | MMC submodule topological structure of equivalent full-bridge submodule with direct-current fault blocking capability |
| CN113708351B (en) * | 2021-07-14 | 2023-08-04 | 中国南方电网有限责任公司超高压输电公司广州局 | Inverter for DC fault ride through and control method |
| CN116184123B (en) * | 2023-04-21 | 2023-07-21 | 山东大学 | Commutation failure judging method based on commutation failure recognition factor |
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| JP4942169B2 (en) * | 2006-09-11 | 2012-05-30 | 東芝三菱電機産業システム株式会社 | 3-level inverter |
| WO2013091676A1 (en) * | 2011-12-19 | 2013-06-27 | Abb Technology Ltd | Multilevel voltage source converter |
| CN103983891B (en) * | 2014-05-30 | 2018-10-09 | 台达电子企业管理（上海）有限公司 | The short trouble detection device and method of inverter circuit |
| CN104300569B (en) * | 2014-09-29 | 2016-04-20 | 华中科技大学 | HVDC dc-side short-circuit fault based on mixed type MMC passes through and restoration methods |
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