CN109659911A - A kind of failure self-cleaning MMC topology suitable for multiterminal element and DC grid - Google Patents
A kind of failure self-cleaning MMC topology suitable for multiterminal element and DC grid Download PDFInfo
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- CN109659911A CN109659911A CN201811523957.9A CN201811523957A CN109659911A CN 109659911 A CN109659911 A CN 109659911A CN 201811523957 A CN201811523957 A CN 201811523957A CN 109659911 A CN109659911 A CN 109659911A
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- failure
- cleaning
- inverter
- mmc
- fault
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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
- H02H7/268—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 for dc systems
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Abstract
The present invention relates to a kind of failure self-cleaning MMC topologys suitable for multiterminal element and DC grid, belong to multiterminal element, DC grid technical field；The failure self-cleaning MMC topology includes inverter unit and line unit, and wherein inverter unit is made of the converter station of improvement structure；Line unit includes Fast mechanical switch, one group of capacitor and several concatenated diodes in parallel.When operating normally, inverter unit is run the failure self-cleaning MMC topology as converter station, identical as normal operating conditions；Line unit is not due to connecing in the line, so nor affecting on system normal operation；In failure by Collaborative Control inverter unit and line unit, realize the removing of failure be isolated.
Description
Technical field
The present invention relates to a kind of failure self-cleaning MMC topologys suitable for multiterminal element and DC grid, and it is straight to belong to multiterminal
Stream, DC grid field.
Background technique
Flexible DC transmission has obtained more and more attention, multi-terminal HVDC transmission and DC grid due to plurality of advantages
Become following trend.But since the fault current of DC line fault does not have zero crossing, so cannot be as ac transmission
Utilize zero crossing arc extinguishing like that, this brings very big difficulty to the realization of dc circuit breaker, current implementation method be divided into
Under it is several: current zero-crossing point is generated based on superimposed oscillation electric current, and then realizes electric current disjunction, the disadvantage is that turn-off delay is too long, is closed
Power-off stream is limited；DC line increases inversion-rectification link, and the exchange side after inversion cuts off electric current with AC circuit breaker, lacks
Point is off delay greatly, could turn off until current zero-crossing point, and loss is big, involves great expense；With a large amount of power electronics device
Part series connection, above lightning arrester connected in parallel, electric current flows through the lower branch of impedance in normal work, play the role of drop it is low-loss,
Electric current is first transferred to power electronics branch when off, then opens disconnecting switch, then is closed with power electronic devices
It is disconnected, fault energy is absorbed with arrester.The disadvantage is that cut-off current is limited, and electric current is first transferred to power electronics when shutdown
Branch also waits for disconnecting switch and fully opens, increases turn-off delay to a certain extent.Part is independent of direct current interruption
The fault clearance strategy of device, such as half full mixed topology are difficult to realize preferable due to biggish number of devices and running wastage
Economy.The exploitation of dc circuit breaker in the following multiterminal element and DC grid still has many problems demands to solve, research
Suitable for high voltage, high current occasion, and with good rapidity, economy DC Line Fault remove strategy have become it is urgent
It is essential and wants.
Summary of the invention
In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a kind of suitable for multiterminal element and DC grid
Failure self-cleaning MMC topology.
It is an object of the invention to overcome current high voltage DC breaker voltage class lower, shutdown is slower, and cost is excessively high
The shortcomings that.
The technical scheme adopted by the invention is that: when operating normally, inverter unit is run as converter station, with
Converter station function is identical, and line unit does not influence the normal operation of system；When DC line fault occurs, inverter unit is logical
The IGBT triggering for making to be connected in parallel between bridge arm reactance is crossed, the DC potential of inverter is down to close to zero potential；At this time on route
Capacitor current potential be higher than inverter, discharge to inverter side so that the fault current between capacitor and inverter reduces, work as failure
When current reduction is to zero, the disconnecting switch on route can disjunction faulty line；The energy of the route storage of the capacitor other side can
To consume energy by diode continuousing flow circuit.
Compared with prior art, the present invention has the advantage that are as follows:
1, turn-off delay is small, since mechanical switch speed is slower, at least needs 2ms, the electricity in conventional hybrid formula breaker
Power electronics cut-off circuit is connected in parallel on mechanical switch branch road, and needing to fully open to mechanical switch could the cutout of latch power electronics
Circuit, then there are also the endergonic process in energy absorption circuit；And the Fast mechanical switch of the breaker does not have parallel branch, in event
When barrier, execute after backup shutdoun and electric current transfer operation can disjunction Fast mechanical switch, after Fast mechanical switch is opened
Failure is just removed, and turn-off delay is reduced.
2, at low cost, the converter station of current engineer application, which is added some circuits, can be transformed into inverter unit, normally
Its function as converter station is not influenced when operation；It connects no longer as hybrid circuit breaker on every route and largely controls entirely
Type device, saves cost.
3, economical operation, a large amount of concatenated wholly-controled devices and energy absorption circuit due to hybrid circuit breaker configuration
Idle state is in when route operates normally, and the program only has energy absorption circuit when operating normally in idle shape
State, running wastage greatly reduce；Inverter unit can be used as converter station use when normal, improve utilization rate.
Detailed description of the invention
The following further describes the present invention with reference to the drawings.
Fig. 1 shows a kind of failure self-cleaning MMC topological structure schematic diagram suitable for multiterminal element and DC grid, packet
Include inverter unit and breaking units, wherein line unit is made of Fast mechanical switch, capacitor, diode；
Fig. 2 shows inverter unit structural schematic diagram, between the upper and lower bridge arm inductance of traditional converter station it is in parallel by
Branch made of IGBT switching group and Diode series, while metal oxide arrester in parallel；
Fig. 3 shows the schematic illustration of fault clearance process；
Fig. 4 shows fault clearance operational flowchart；
Fig. 5 shows reclosing strategic process schematic diagram.
Specific embodiment
Below in conjunction with the attached drawing in the embodiment of the present application, technical solutions in the embodiments of the present application carries out clear, complete
Site preparation description.
It is a kind of suitable for the failure self-cleaning MMC topological structure of multiterminal element and DC grid as shown in Figure 1, include the change of current
Device unit and breaking units, wherein line unit is made of Fast mechanical switch, capacitor, diode；Fig. 2 is to inverter topology
Structure has carried out further displaying, in parallel by IGBT switching group and diode between the upper and lower bridge arm inductance of traditional converter station
The branch being connected in series, while metal oxide arrester in parallel；Wherein, the quantity of IGBT switching group and concatenated diode
It is determined by bridge arm reactance both end voltage, usually up to a hundred.
Fault clearance principle by being latched all submodules, while triggering the T in ICM as shown in figure 3, when failure3, will
Inverter current potential is down to close to zero potential, at this point, other are simultaneously to fault point and the inverter feed-in fault current；Capacitance voltage
For AC line voltage, capacitor discharges to both ends at this time, wherein the part discharged to converter station just will be by disconnecting switch
Current canceling, so that disconnecting switch can disconnect faulty line.
Fault clearance operational flowchart is as shown in Figure 4:
t0Direct-current short circuit failure occurs for the moment, and after wave transmission delay, fault current starts to increase rapidly all converter stations
Greatly.Due to the presence of line inductance, the large percentage of fault current shared by the closer inverter of distance fault point.
t1The DC voltage of proximal end inverter is reduced to the on-state voltage drop of IGBT as failure is positioned by the moment, so that
The energy stored in DC line is dissipated by the circuit that diode, faulty line and fault point are formed, and not will cause electricity
Stream was decayed slow problem.
t2At the moment, when the current attenuation in disconnecting switch is to 0, disjunction UFD is with isolated fault route.
t3At the moment, as UFD fracture reaches maximum breaking gap, failure is successfully isolated, and at this time can restore inverter
To normal operating condition.
Reclosing operation process is as shown in figure 5, first determine whether fault type, for permanent fault, without reclosing,
Directly carry out trouble hunting；When transient fault, have the UFD with point combined floodgate ability for sulfur hexafluoride gas type UFD etc., it can be with
Directly it is closed；For not having the UFD of electrification combined floodgate ability, then needs first to carry out Converter DC-side drop voltage operation, be UFD
Combined floodgate create conditions, to restore inverter normal operating condition after UFD closing success again.
Finally it should be noted that: described embodiment is only some embodiments of the present application, rather than whole realities
Apply example.Based on the embodiment in the application, those of ordinary skill in the art are obtained without making creative work
Every other embodiment, shall fall in the protection scope of this application.
Claims (5)
1. a kind of failure self-cleaning MMC topology suitable for multiterminal element and DC grid, it is characterised in that: including inverter list
First (1), line unit (2)；Wherein inverter unit include wholly-controled device (IGBT, IGCT etc.), diode, bridge arm inductance,
Metal oxide arrester, conducting wire etc.；Line unit includes Fast mechanical switch, capacitor, diode etc..
2. a kind of failure self-cleaning MMC topology suitable for multiterminal element and DC grid according to claim 1, special
Sign is: the composed structure of its inverter unit are as follows: in parallel by several between the upper and lower bridge arm inductance of traditional converter station
Branch made of IGBT switching group and Diode series, while metal oxide arrester in parallel；Converter station using half-bridge MMC,
The topologys such as full-bridge MMC, half full-bridge mixing MMC, the circuit ends when normal operation, inverter unit as converter station operation, with
The function of converter station is the same, and the inverter unit for removing failure as auxiliary when failure uses.
3. a kind of failure self-cleaning MMC topology suitable for multiterminal element and DC grid according to claim 1, special
Sign is: line unit is made of Fast mechanical switch, capacitor, diode, and wherein Fast mechanical switch series connection is on the line, electric
Hold and diodes in parallel forms residual current bleed-off circuit, connects between route and earthing pole.
4. a kind of failure self-cleaning MMC topology suitable for multiterminal element and DC grid according to claim 1, special
Sign is: when DC line fault occurs, inverter unit will be changed by triggering the IGBT being connected in parallel between bridge arm reactance
The DC potential of stream device is down to close to zero potential；The capacitor current potential on route is higher than inverter at this time, makes to the electric discharge of inverter side
The fault current obtained between capacitor and inverter reduces, and when fault current is reduced to zero, the disconnecting switch on route can divide
Disconnected faulty line；The energy of the route storage of the capacitor other side can consume energy by diode continuousing flow circuit.
5. a kind of failure self-cleaning MMC topology suitable for multiterminal element and DC grid according to claim 1, special
Sign is: after route fault clearance, whether shaken by detecting to be removed on route during the reduction of electric current, it can
Judge the type of failure, then determines reclosing strategy；If electric current shakes, failure is transient fault, can carry out weight
Closing operation, if electric current does not shake, failure is permanent fault, not can be carried out reclosing at this time；This mode can be with
It avoids system from coinciding with permanent fault and then causes to generate bigger loss.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811523957.9A CN109659911A (en) | 2018-12-13 | 2018-12-13 | A kind of failure self-cleaning MMC topology suitable for multiterminal element and DC grid |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811523957.9A CN109659911A (en) | 2018-12-13 | 2018-12-13 | A kind of failure self-cleaning MMC topology suitable for multiterminal element and DC grid |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112039354A (en) * | 2020-09-11 | 2020-12-04 | 华北电力大学 | Parallel hybrid MMC topology suitable for flexible direct-current power grid fault clearing |
| CN112269145A (en) * | 2020-10-14 | 2021-01-26 | 广西电网有限责任公司电力科学研究院 | Zero potential fault clearing method and system for power distribution network |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105281287A (en) * | 2015-10-22 | 2016-01-27 | 中国科学院电工研究所 | Thyristor-based direct current breaker topology with bidirectional blocking function |
| CN106300296A (en) * | 2016-09-08 | 2017-01-04 | 华北电力大学 | A kind of actively short-circuit type high voltage DC breaker |
| CN207265895U (en) * | 2017-08-29 | 2018-04-20 | 华北电力大学（保定） | DC Line Fault passes through MMC submodules and the transverter with the submodule |
| CN108599120A (en) * | 2018-03-27 | 2018-09-28 | 中国科学院电工研究所 | A kind of direct current current-limiting circuit breaker |
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2018
- 2018-12-13 CN CN201811523957.9A patent/CN109659911A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105281287A (en) * | 2015-10-22 | 2016-01-27 | 中国科学院电工研究所 | Thyristor-based direct current breaker topology with bidirectional blocking function |
| CN106300296A (en) * | 2016-09-08 | 2017-01-04 | 华北电力大学 | A kind of actively short-circuit type high voltage DC breaker |
| CN207265895U (en) * | 2017-08-29 | 2018-04-20 | 华北电力大学（保定） | DC Line Fault passes through MMC submodules and the transverter with the submodule |
| CN108599120A (en) * | 2018-03-27 | 2018-09-28 | 中国科学院电工研究所 | A kind of direct current current-limiting circuit breaker |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112039354A (en) * | 2020-09-11 | 2020-12-04 | 华北电力大学 | Parallel hybrid MMC topology suitable for flexible direct-current power grid fault clearing |
| CN112269145A (en) * | 2020-10-14 | 2021-01-26 | 广西电网有限责任公司电力科学研究院 | Zero potential fault clearing method and system for power distribution network |
| CN112269145B (en) * | 2020-10-14 | 2023-04-07 | 广西电网有限责任公司电力科学研究院 | Zero potential fault clearing method and system for power distribution network |
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