CN107658842A - DC side fault protection system and method based on MMC submodules topology - Google Patents

DC side fault protection system and method based on MMC submodules topology Download PDF

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Publication number
CN107658842A
CN107658842A CN201711091438.5A CN201711091438A CN107658842A CN 107658842 A CN107658842 A CN 107658842A CN 201711091438 A CN201711091438 A CN 201711091438A CN 107658842 A CN107658842 A CN 107658842A
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fault
mmc
current
module
protection
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CN107658842B (en
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马静
项晓强
康文博
李沛
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North China Electric Power University
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North China Electric Power University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
    • H02H3/087—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current for dc applications
    • 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
    • H02H7/10—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 for converters; for rectifiers
    • H02H7/12—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 for converters; for rectifiers for static converters or rectifiers
    • H02H7/125—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 for converters; for rectifiers for static converters or rectifiers for rectifiers
    • 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
    • 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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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)
  • Rectifiers (AREA)

Abstract

The invention belongs to MMC HVDC system dcs side technical field of relay protection, more particularly to a kind of DC side fault protection system and method based on MMC submodules topology.The system includes the connected MMC HVDC systems transverter of order, data read in module, logic judgment module and protection act module；Wherein MMC HVDC systems transverter is made up of MMC submodules and additional resistance module, additional resistance module by inverse parallel IGBT it is in parallel with additional resistance after be connected on DC side circuit；MMC submodules install a resistance-capacitance absorption device additional between multiple series thyristors, and one group of antiparallel IGBT and diode are added in submodule.Methods described includes gathered data, low pressure overcurrent protection logic judgment and fault current decay and judged; the invention efficiently solve double-thyristor method cause IGCT surprisingly to turn on when removing MMC HVDC system dcs side failures, diode damage, and the Fault Isolation time length cause system security and stability reduce the problem of.

Description

DC side fault protection system and method based on MMC submodules topology
Technical field
The invention belongs to MMC-HVDC system dcs side technical field of relay protection, more particularly to one kind to be based on MMC submodules The DC side fault protection system and method for block topology.
Background technology
It is difficult to quickly locate when by serious impact from DC side failure based on the MMC topological structures of half-bridge submodule Reason, so as to cause serious impact to the side system of alternating current-direct current two.Therefore, it is engineering circles and academia to deal carefully with DC line fault Key issue urgently to be resolved hurrily.
At present, correlative study, most representational master are carried out for the transverter topology with DC Line Fault isolating power There are two types：The first is using full-bridge submodule and clamper Shuangzi module as representative, after DC line breaks down, by son Put into fault paths to module capacitance reversed polarity, so as to eliminate fault current.Second mainly using double-thyristor method as representative, After DC line breaks down, to avoid the occurrence of uncontrollable rectifier bridge, by opening inverse parallel double-thyristor, arteface bridge Arm path, cut-out AC power supply realize Failure elimination to the short circuit current of DC line feed-in.Transverter is based on the first kind Failure separation method compare, double-thyristor method cost of investment, additional power losses, control complexity etc. be respectively provided with compared with Big advantage.
But double-thyristor method there are still some drawbacks, one is in system normal operation, IGCT will bear by High forward voltage rate of change caused by IGBT switching submodule electric capacity, the unexpected conducting of IGCT may be caused.The second is locking Transverter and after turning on submodule double-thyristor, diode must share short circuit current, still there is the possibility of damage.The third is the time is normal When number is excessive, DC line fault current attenuation is slow, is unfavorable for Fault Isolation and system safety and stability.
The content of the invention
In view of the above-mentioned problems, the present invention provides a kind of DC side fault protection system based on MMC submodules topology and side Method, IGCT is caused surprisingly to turn on when removing MMC-HVDC system dcs side failure to solve double-thyristor method, diode damage The problem of bad, and Fault Isolation time length causes system security and stability to reduce.
A kind of DC side fault protection system based on MMC submodules topology, including：
The connected MMC-HVDC systems transverter of order, data read in module, logic judgment module and protection act module；
The MMC-HVDC systems transverter is by the MMC submodules that are connected on bridge arm and is connected on the attached of DC side circuit Resistive module is added to form；Wherein, each MMC submodules configure antiparallel double-thyristor S1, S2, anti-simultaneously with IGCT S1 A resistance-capacitance absorption device in parallel between the IGCT S2 of multiple series connection of connection, the resistance-capacitance absorption device is by resistance RnAnd electric capacity CnIt is composed in series, causes IGCT S2 to mislead for suppressing high forward voltage rate of change caused by submodule switching；In son The IGBT2 and diode D2 of module antiparallel IGBT3 and the diode D3 of one group of one end differential concatenation, for blocking short-circuit electricity The path on diode D2 is flowed, protection diode D2 is without damage；The additional resistance module is by one group of antiparallel IGBT With additional resistance RaddCompose in parallel, for accelerating direct fault current to decay；
The data read in DC side electric current, the voltage signal that module is used to gather MMC-HVDC system transverters, concurrently Deliver to logic judgment module；
The logic judgment module carries out low pressure overcurrent protection according to DC side fault current, the voltage signal of collection Logic judgment, and obtained fault message is sent to protection act module；
The protection act module sends block signal according to fault message to corresponding transverter and breaker.
The method of work of the MMC-HVDC systems transverter is：
During MMC-HVDC system normal operations, the IGBT3 in MMC submodules is in the conduction state all the time, inverse parallel twin crystal Brake tube S1, S2 are in blocking all the time；Inverse parallel IGBT in additional resistance module is in the conduction state, additional resistance Radd It is short-circuited；
When DC side breaks down, the IGBT3 in MMC submodules is turned off, blocks short circuit current in sustained diode 2 Path, it is without damage with protection diode；Meanwhile resistance-capacitance absorption device utilizes the characteristic that electric capacity both end voltage can not be mutated, High forward voltage rate of change caused by suppressing submodule switching, prevents antiparallel IGCT S2 from misleading；Turn off additional electrical Hinder the inverse parallel IGBT, additional resistance R in moduleaddFault loop is accessed, accelerates direct fault current decay.
A kind of DC side fault protecting method based on MMC submodules topology, comprises the following steps：
Step 1：Gathered data, including DC side positive and negative electrode transmission route survey voltage signal, DC side positive and negative electrode are defeated Electric line measures current signal；
Step 2：Low pressure overcurrent protection logic judgment is carried out according to the data of collection, if it is determined that DC side breaks down, Then low pressure overcurrent protection acts and sends block signal to corresponding current conversion station；
Step 3：After current conversion station receives block signal, rapid each bridge arm submodule of locking transverter, by additional resistance RaddThrow Enter in discharge loop, trigger inverse parallel double-thyristor in submodule, short circuit current is entered the decling phase；
Step 4：Whether failure judgement electric current, which decays, finishes, if it is determined that fault current decay finishes, reopens transverter, Inverse parallel double-thyristor on locking submodule, and the IGBT on locking DC line, make additional resistance RaddIn loop, Permanent fault is avoided to cause large impact；
Step 5：Return to step 2 re-starts low pressure overcurrent protection logic judgment, if low pressure overcurrent protection acts, Block signal is sent to transverter rapidly, again locking submodule, and trip signal is sent to breaker, if protection is failure to actuate, Then system recovers normal operation, exits additional resistance Radd。
The decision method of the low pressure overcurrent protection logic judgment is：
When DC side positive and negative electrode transmission route survey difference in voltage absolute value is less than under-voltage protection setting valve, while directly Stream side transmission line of electricity negative or positive electrode measurement current absolute value is more than overcurrent protection setting valve, then is determined as that event occurs for DC side Barrier.
The failure judgement electric current judgment basis finished of whether decaying is：When the survey of DC side transmission of electricity positive and negative electrode circuit When amount electric current is respectively less than current attenuation setting valve, then it is determined as that fault current decay finishes.
The beneficial effects of the present invention are：
A kind of DC side fault protection system and method based on MMC submodules topology proposed by the present invention efficiently solve Double-thyristor method causes IGCT surprisingly to turn on when removing MMC-HVDC system dcs side failure, diode damage, and failure The problem of isolation time length causes system security and stability to reduce.Specifically include：
1) MMC submodules proposed by the present invention can effectively avoid IGCT mislead trigger the system failure danger, simultaneously Path of the short circuit current on fly-wheel diode can be blocked, protection diode is without damage.
2) resistance-capacitance absorption device proposed by the present invention, the characteristic that can not be mutated using electric capacity both end voltage, submodule is suppressed High forward voltage rate of change caused by switching, can effectively prevent IGCT S2 from misleading, and do not influence MMC-HVDC systems just Often operation.
3) the additional resistance module that the present invention connects on DC side circuit, when system dc side failure, by additional electrical Resistance access fault loop, can accelerate direct fault current to decay, and then solve because Fault Isolation time length causes system to be pacified The problem of total stability reduces.
Brief description of the drawings
Accompanying drawing 1 is the DC side fault protection system structural representation based on MMC submodules topology；
Accompanying drawing 2 is MMC-HVDC system transverter topological diagrams；
Accompanying drawing 3 is MMC submodule topological diagrams；(Figure of abstract)
Accompanying drawing 4 is the DC side fault protecting method flow chart based on MMC submodules topology；
Accompanying drawing 5 is MMC-HVDC analogue system schematic diagrames in embodiment 1；
Accompanying drawing 6 is that IGCT S2 bears voltage change ratio simulation result in embodiment 1；
Accompanying drawing 7 is the Neutron module switching voltage change simulation result of embodiment 1；
Accompanying drawing 8a is the transient fault short circuit current simulation result of fault distance x=0 in embodiment 1；
Accompanying drawing 8b is the transient fault short circuit current simulation result of fault distance x=50 in embodiment 1；
Accompanying drawing 8c is the transient fault short circuit current simulation result of fault distance x=150 in embodiment 1；
Accompanying drawing 9a is the transient fault capacitance voltage simulation result of fault distance x=0 in embodiment 1；
Accompanying drawing 9b is the transient fault capacitance voltage simulation result of fault distance x=50 in embodiment 1；
Accompanying drawing 9c is the transient fault capacitance voltage simulation result of fault distance x=150 in embodiment 1；
Accompanying drawing 10a is the permanent fault short circuit current simulation result of fault distance x=0 in embodiment 1；
Accompanying drawing 10b is the permanent fault short circuit current simulation result of fault distance x=50 in embodiment 1；
Accompanying drawing 10c is the permanent fault short circuit current simulation result of fault distance x=150 in embodiment 1；
Accompanying drawing 11a is the permanent fault capacitance voltage simulation result of fault distance x=0 in embodiment 1；
Accompanying drawing 11b is the permanent fault capacitance voltage simulation result of fault distance x=50 in embodiment 1；
Accompanying drawing 11c is the permanent fault capacitance voltage simulation result of fault distance x=150 in embodiment 1；
Embodiment
The present invention is described in detail with reference to the accompanying drawings and examples.
IGCT is caused surprisingly to turn on when removing MMC-HVDC system dcs side failure to solve double-thyristor method, two poles The problem of pipe damages, and Fault Isolation time length causes system security and stability to reduce, the present invention propose that one kind is based on MMC submodules The DC side fault protection system of block topology, the structural representation of the DC side fault protection system is as shown in figure 1, including suitable The connected MMC-HVDC systems transverter of sequence, data read in module, logic judgment module and protection act module；Data read in mould Block first sends DC side electric current, the voltage signal of the MMC-HVDC system transverters of collection to logic judgment module, logic Judge module according to DC side fault current, the voltage signal of collection, sentence by the low pressure overcurrent protection logic exported through transverter It is disconnected, fault message is obtained, and fault message is sent to protection act module；Protection act module is according to fault message, Xiang Xiang The transverter answered sends block signal, and sends block signal to corresponding breaker；
Accompanying drawing 2 is MMC-HVDC system transverter topological diagrams, as shown in Fig. 2 the MMC-HVDC systems transverter is by even The MMC submodules being connected on bridge arm and the additional resistance module composition for being connected on DC side circuit；Because down slope time is normal Number τ directly affects Fault Isolation and system safety and stability, and down slope time constant, τ is bigger, DC line fault current attenuation It is slower, remove failure when it is longer to the system excessively stream attack time, be more unfavorable for the safety and relaying configuration of AC system.And pass through The loop resistance or method of loop inductance can reduce timeconstantτ after reducing failure after increase failure.Therefore, the present invention is in direct current One is connected on side line road by inverse parallel IGBT and additional resistance RaddThe additional resistance module composed in parallel, system normal operation When, antiparallel IGBT is in the conduction state, parallel resistance RaddIt is short-circuited, therefore system operation loss will not be increased, system is straight Antiparallel IGBT is turned off after flowing side failure, parallel resistance RaddFault loop is accessed, accelerates direct fault current decay.
Accompanying drawing 3 is MMC submodule topological diagrams, as shown in figure 3, each MMC submodules configure antiparallel double-thyristor S1, S2 (convenient for the sake of, S2 will be referred to as with the antiparallel IGCTs of S1), with the antiparallel multiple crystalline substances connected of IGCT S1 A resistance-capacitance absorption device in parallel, the resistance-capacitance absorption device are composed in series by resistance Rn and electric capacity Cn, are used between brake tube S2 High forward voltage rate of change caused by suppressing submodule switching causes IGCT S2 to mislead；In the IGBT2 of submodule and two Pole pipe D2 antiparallel IGBT3 and the diode D3 of one group of one end differential concatenation, for blocking short circuit current in diode D2 Path, protection diode D2 is without damage；The additional resistance module is by one group of antiparallel IGBT and additional resistance RaddAnd Connection composition, for accelerating direct fault current to decay；
When MMC-HVDC system normal operations, IGBT3 is in the conduction state all the time, IGCT S1, antiparallel brilliant lock Pipe system S2 is in blocking all the time, and the circulation path of electric current is as shown in Figure 1.Locking submodule is needed when DC side breaks down When, turn off IGBT3 trigger signal, you can block path of the short circuit current in sustained diode 2, protection diode not by Damage.Resistance-capacitance absorption device utilizes the characteristic that electric capacity both end voltage can not be mutated, and suppresses high positive caused by submodule switching Voltage change ratio du/dt, even if du/dt makes the IGCT of top half mislead, shunt capacitance still can effectively protect lower half Divide IGCT unaffected, therefore can effectively prevent IGCT S2 from misleading, and do not influence MMC-HVDC system normal operations.
Accompanying drawing 4 is the DC side fault protecting method flow chart based on MMC submodules topology, as shown in figure 4, methods described Including：
Step 1：Gathered data, including DC side positive and negative electrode transmission route survey voltage signal, DC side positive and negative electrode are defeated Electric line measures current signal；
Step 2：After DC side failure occurs, the low pressure overcurrent protection for being installed on current conversion station outlet detects DC side After fault current rise and voltage landing, act and send current conversion station block signal, its operation equation is：
In formula：UdP、UdNIt is the measurement voltage of DC side positive and negative electrode transmission line of electricity respectively, IdP、IdNIt is that DC side is defeated respectively The measurement electric current of electric positive and negative electrode circuit, Uset、Iset1It is low-voltage, overcurrent protection setting valve respectively；
Step 3：According to fault message, if it is determined that DC side breaks down, block signal, the change of current are sent to corresponding current conversion station Station receives block signal, rapid each bridge arm submodule of locking, by submodule capacitive bypass, while in each submodule of locking IGBT3, block short circuit current circulation path in diode D2.IGBT on locking DC line, make additional resistance RaddInput In discharge loop, inverse parallel double-thyristor in submodule is triggered, short circuit current is entered the decling phase, whether failure judgement electric current Decay finishes, and its criterion is：
|IdP|and|IdN| ＜ Iset2 (2)
I in formulaset2For current attenuation setting valve；
Step 4：When DC side measurement electric current meets formula (2), MMC-HVDC transverters are reopened, on locking submodule Inverse parallel double-thyristor, while keep IGBT lockings on DC line, make additional resistance RaddStill in loop, avoid permanent Property failure caused large impact；
Step 5：Low pressure overcurrent protection logic judgment is re-started, if low pressure overcurrent protection acts, and rapidly to changing Flow device and send block signal, again locking submodule, and trip signal is sent to breaker, if low pressure overcurrent protection is not again Action, then prove that failure has disappeared, the additional resistance that can be exited on DC line.
Embodiment 1
To verify the validity of DC side fault protection system and method based on MMC submodules topology, the present embodiment exists MMC-HVDC system simulation models are built on RTDS platforms and carry out simulating, verifying, are imitated using MMC-HVDC systems as shown in Figure 5 True mode carry out respectively IGCT S2 bear forward voltage rate of change emulation, abort situation apart from current conversion station outlet 0km, 50km, 150km transient faults emulate, and abort situation is apart from current conversion station outlet 0km, 50km, 150km permanent fault emulation.
(1) when systems are functioning properly, the voltage change ratio emulation knot born to the IGCT S2 in sub- module topology Fruit is as shown in fig. 6, caused high forward voltage rate of change carries out simulation result as shown in fig. 7, contrast during switching submodule electric capacity Fig. 6 and 7 understands that in submodule topology, the order of magnitude for the voltage change ratio that IGCT S2 is born is 10-3, much smaller than switching Caused high forward voltage rate of change during module capacitance, it can be seen that, IGCT S2 when the present invention can avoid system normal operation Logical danger is misled into because bearing high forward voltage rate of change.
(2) when transient fault occurs for system, it is assumed that transient fault, fault bit occur in t=3s for DC line It is set at current conversion station outlet xkm.After failure occurs, transient fault when fault distance is respectively 0km, 50km, 150km is short Road current simulations result is as shown in Fig. 8 a~8c, transient fault capacitance voltage when fault distance is respectively 0km, 50km, 150km For simulation result as shown in Fig. 9 a~9c, whole process can be divided into 3 stages：
(I) fault current ascent stage
Fault current ascent stage from failure generation moment to the current conversion station locking moment, i.e. t in Fig. 8 a~8c1-t2When Section, whole process last about greatly 10ms.At this stage, fault current according to the discharge current of order Oscillating circuit capacitance change Rule rises, and different fault distances corresponds to different fault current maximums：Fault distance is more remote, and fault current maximum is got over It is small；Fault distance is nearer, and fault current maximum is bigger.Meanwhile the capacitance voltage of each submodule drops rapidly from rated voltage Fall, such as t in Fig. 9 a~9c1-t2Shown in period.
(II) fault current removing stage
After failure occurs, overcurrent under-voltage protection starts rapidly, and block signal is sent to current conversion station, into fault current T in removing stage, i.e. Fig. 8 a~8c2-t3Period.In the presence of submodule topology, after current conversion station locking, exchange side system feedback The electric current entered flows using the double-thyristor in each submodule as path in bridge arm, eliminates the uncontrollable rectifier bridge effect of diode Should, the fault current contributed in DC line is removed.Meanwhile diode D2 no longer shares short circuit current, avoids damage May.From Fig. 8 a~8c, fault current decays to zero according to curent change rule in First Order Circuit, and die-away time is A few tens of milliseconds, the total resistance value that decay speed is depended in whole loop, additional series resistance RaddBigger, die-away time is normal Number is smaller, is more advantageous to system safety and stability.Such as t in Fig. 9 a~9c2-t3It is at this stage, each after current conversion station locking shown in period Submodule electric capacity is in bypass condition, is no longer discharged to trouble point, and its voltage keeps constant.
(III) the fault recovery stage
After detecting that DC side fault current decays to zero, transverter is reopened and by the twin crystal lock in each submodule T in locking, i.e. Fig. 8 a~8c3-t4Period.For transient fault, trouble point has disappeared after DC side fault current decays to zero Lose, short circuit current does not occur again.Such as t in Fig. 9 a~9c3-t4Shown in period, due to current conversion station quick lock after failure, each submodule Block capacitance voltage still keeps higher level, and after reopening current conversion station, capacitance voltage can rise to specified within a few tens of milliseconds Level, MMC-HVDC systems can resume operation rapidly, improve system availability.
(3) when permanent fault occurs for system, if permanent fault, abort situation occur in t=3s for DC line To be exported apart from current conversion station at xkm.After failure occurs, permanent fault short circuit when fault distance is respectively 0km, 50km, 150km Current simulations result is as shown in Figure 10 a~10c, permanent fault capacitance voltage when fault distance is respectively 0km, 50km, 150km Simulation result is as shown in Figure 11 a~11c, and whole process can equally be divided into fault current rising, fault current is removed and failure is extensive Multiple three phases, wherein fault current ascent stage and fault current removing stage is similar with transient fault, no longer superfluous herein State.Difference is the fault recovery stage, such as t in Figure 10 a~10c3-t4Shown in period, when detecting DC side fault current After decaying to zero, transverter is reopened and by the double-thyristor locking in each submodule.Such as t in 11a~11c3-t4Period institute Show, for permanent fault, trouble point still suffers from after reopening transverter, therefore fault current will occur again, each submodule Block capacitance voltage further reduces.But due to after open transverter not by additional resistance RaddExcision, therefore coincide with permanent event The secondary pulse of short circuit current during barrier is simultaneously little, such as t in Figure 10 a~10c4-t5Shown in period.When overcurrent, low-voltage protection After monitoring failure again, rapid locking transverter, fault current will gradually decay.To further ensure that system safety, disconnect AC breaker, straight-flow system is isolated.
The result shows, a kind of DC side fault protection system based on MMC submodules topology proposed by the present invention and Method is avoided that IGCT misleads and triggers the danger of the system failure, while short circuit current can be blocked logical on fly-wheel diode Road, protection diode are without damage.For transient fault, because submodule capacitor voltage is still protected after current conversion station is reopened Higher level is held, therefore MMC-HVDC systems can resume operation rapidly after failure.For permanent fault, after open current conversion station Short circuit current impacts little to secondary system when additional resistance is not cut off, therefore coincides with permanent fault, can still pass through Rapid locking current conversion station, disconnects AC circuit breaker, isolated fault.
This embodiment is only the preferable embodiment of the present invention, but protection scope of the present invention is not limited thereto, Any one skilled in the art the invention discloses technical scope in, the change or replacement that can readily occur in, It should all be included within the scope of the present invention.Therefore, protection scope of the present invention should be with scope of the claims It is defined.

Claims (5)

  1. A kind of 1. DC side fault protection system based on MMC submodules topology, it is characterised in that including：
    The connected MMC-HVDC systems transverter of order, data read in module, logic judgment module and protection act module；
    The MMC-HVDC systems transverter is by the MMC submodules that are connected on bridge arm and the additional electrical for being connected on DC side circuit Hinder module composition；Wherein, each MMC submodules configure antiparallel double-thyristor S1, S2, antiparallel with IGCT S1 A resistance-capacitance absorption device in parallel between the IGCT S2 of multiple series connection, the resistance-capacitance absorption device is by resistance RnWith electric capacity CnString Connection composition, causes IGCT S2 to mislead for suppressing high forward voltage rate of change caused by submodule switching；In submodule IGBT2 and diode D2 antiparallel IGBT3 and the diode D3 of one group of one end differential concatenation, for blocking short circuit current to exist Path on diode D2, protection diode D2 are without damage；The additional resistance module by one group of antiparallel IGBT with it is attached Power-up resistance RaddCompose in parallel, for accelerating direct fault current to decay；
    The data read in DC side electric current, the voltage signal that module is used to gather MMC-HVDC system transverters, and send extremely Logic judgment module；
    The logic judgment module carries out low pressure overcurrent protection logic according to DC side fault current, the voltage signal of collection Judge, and obtained fault message is sent to protection act module；
    The protection act module sends block signal according to fault message to corresponding transverter and breaker.
  2. 2. a kind of DC side fault protection system based on MMC submodules topology according to claim 1, its feature exist In the method for work of the MMC-HVDC systems transverter is：
    During MMC-HVDC system normal operations, the IGBT3 in MMC submodules is in the conduction state all the time, inverse parallel double-thyristor S1, S2 are in blocking all the time；Inverse parallel IGBT in additional resistance module is in the conduction state, additional resistance RaddIt is short Road；
    When DC side breaks down, the IGBT3 in MMC submodules is turned off, blocks short circuit current logical in sustained diode 2 Road, it is without damage with protection diode；Meanwhile resistance-capacitance absorption device utilizes the characteristic that electric capacity both end voltage can not be mutated, suppress High forward voltage rate of change caused by submodule switching, prevents antiparallel IGCT S2 from misleading；Turn off additional resistance mould Inverse parallel IGBT in block, additional resistance RaddFault loop is accessed, accelerates direct fault current decay.
  3. 3. a kind of DC side fault protecting method based on MMC submodules topology, it is characterised in that comprise the following steps：
    Step 1：Gathered data, including DC side positive and negative electrode transmission route survey voltage signal, DC side positive and negative electrode power transmission line Drive test amount current signal；
    Step 2：Low pressure overcurrent protection logic judgment is carried out according to the data of collection, if it is determined that DC side breaks down, then it is low Press through current protection action and send block signal to corresponding current conversion station；
    Step 3：After current conversion station receives block signal, rapid each bridge arm submodule of locking transverter, by additional resistance RaddInput is put In electrical circuit, inverse parallel double-thyristor in submodule is triggered, short circuit current is entered the decling phase；
    Step 4：Whether failure judgement electric current, which decays, finishes, if it is determined that fault current decay finishes, reopens transverter, locking Inverse parallel double-thyristor on submodule, and the IGBT on locking DC line, make additional resistance RaddIn loop, avoid Permanent fault caused large impact；
    Step 5：Return to step 2 re-starts low pressure overcurrent protection logic judgment, if low pressure overcurrent protection acts, rapidly Block signal is sent to transverter, again locking submodule, and trip signal is sent to breaker, if protection is failure to actuate, be System recovers normal operation, exits additional resistance Radd。
  4. 4. a kind of DC side fault protecting method based on MMC submodules topology according to claim 3, its feature exist In the decision method of the low pressure overcurrent protection logic judgment is：
    When DC side positive and negative electrode transmission route survey difference in voltage absolute value is less than under-voltage protection setting valve, while DC side Transmission line of electricity negative or positive electrode measurement current absolute value is more than overcurrent protection setting valve, then is determined as that DC side breaks down.
  5. 5. a kind of DC side fault protecting method based on MMC submodules topology according to claim 3, its feature exist It is in, the failure judgement electric current judgment basis finished of whether decaying：When the measurement electric current of DC side transmission of electricity positive and negative electrode circuit Respectively less than current attenuation setting valve when, then be determined as fault current decay finish.
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CN108448542A (en) * 2018-02-07 2018-08-24 许继集团有限公司 Sub-modular structure with alternating current-direct current fault clearance ability and MMC topological structures
CN113904573A (en) * 2021-10-13 2022-01-07 山东大学 Half-bridge improved MMC sub-module topological structure and control method thereof

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WO2015074689A1 (en) * 2013-11-20 2015-05-28 Siemens Aktiengesellschaft A high voltage converter circuit equipped with a voltage monitoring device
CN104953571A (en) * 2015-07-03 2015-09-30 天津大学 Improved MMC (modular multi-level converter) structure with direct current fault clearing capacity
CN106058824A (en) * 2016-05-26 2016-10-26 华北电力大学 MMC topology having DC fault removing capability
CN206211517U (en) * 2016-12-05 2017-05-31 国网浙江临海市供电公司 A kind of overvoltage protective system of silicon controlled rectifier

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CN104953571A (en) * 2015-07-03 2015-09-30 天津大学 Improved MMC (modular multi-level converter) structure with direct current fault clearing capacity
CN106058824A (en) * 2016-05-26 2016-10-26 华北电力大学 MMC topology having DC fault removing capability
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CN108448542A (en) * 2018-02-07 2018-08-24 许继集团有限公司 Sub-modular structure with alternating current-direct current fault clearance ability and MMC topological structures
CN113904573A (en) * 2021-10-13 2022-01-07 山东大学 Half-bridge improved MMC sub-module topological structure and control method thereof
CN113904573B (en) * 2021-10-13 2023-10-27 山东大学 Half-bridge improved MMC submodule topological structure and control method thereof

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