CN208063039U - A kind of flexible direct current power transmission system - Google Patents
A kind of flexible direct current power transmission system Download PDFInfo
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- CN208063039U CN208063039U CN201820585762.6U CN201820585762U CN208063039U CN 208063039 U CN208063039 U CN 208063039U CN 201820585762 U CN201820585762 U CN 201820585762U CN 208063039 U CN208063039 U CN 208063039U
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- 239000003990 capacitor Substances 0.000 claims description 6
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- 238000000034 method Methods 0.000 description 9
- 238000010586 diagram Methods 0.000 description 7
- 230000005611 electricity Effects 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 5
- 238000011144 upstream manufacturing Methods 0.000 description 5
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- 230000002159 abnormal effect Effects 0.000 description 3
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- 230000008859 change Effects 0.000 description 2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
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Abstract
The utility model provides a kind of flexible direct current power transmission system, and the system comprises transformer, transverter and mutual reactors；The mutual reactor includes upper bridge arm mutual reactor and lower bridge arm mutual reactor, wherein, the upper bridge arm mutual reactor is connected by Same Name of Ends with the connection at different name end with lower bridge arm mutual reactor, and the tie point at the Same Name of Ends and the different name end is grid entry point；One end of the transformer is connect with AC network, and the other end is connect with the grid entry point；The transverter includes three phase elements, and the phase element includes upper bridge arm and lower bridge arm, and the mutual reactor is connected between the upper bridge arm and the lower bridge arm.
Description
Technical field
The utility model is related to direct current transportation field, espespecially a kind of flexible direct current power transmission system.
Background technology
With the increasingly increase of the increasingly depleted and improvement environmental pressure of fossil energy, China or even the world are faced with energy
The strategical adjustment of source structure, large-scale development and utilization new energy are imperative.The new energy such as wind-powered electricity generation, solar energy, tide energy
All have the characteristics that intermittent, randomness, the scale consumption of new energy become the great reality that Power System in China faces and asks
Topic, conventional electric power equipment, electric network composition and running technology have seemed unable to do what one wishes.In order to adapt to the deep change of future source of energy pattern
Change, need to accelerate novel to collect submitting and the research and development of consumption technology to improve the utilization ratio of generation of electricity by new energy.In recent years, scholars
Again power grid transmission & distribution power technology is examined closely, DC techniques become research hotspot again, and the concepts such as flexible direct current power grid are come into being.
The characteristics of failure of flexible direct current power transmission system has its own, fault current rise rapid.Flexible DC power transmission system
System generally use modularization multi-level converter, when ground connection or interpolar failure occur for DC side in system, modular multilevel
Capacitance in transverter is existed by insulated gate bipolar transistor (insulated gate bipolar thyristor, IGBT)
It discharges fault point in the extremely short time, line current is caused to rise rapidly.Short circuit current rises fast at this time, and amplitude is big, for
The security presence larger hidden danger of IGBT equipment.
When modularization multi-level converter breaks down, short circuit current will produce.The short circuit current flowed through on circuit at this time
It is divided into two parts, when first part is that failure occurs, the electric current that the capacitor of power module is discharged by IGBT, this part
Electric current rises soon, and amplitude is big；Second part be IGBT locking after, three-phase alternating current net side by reactor and power module with
The fault current that the antiparallel fly-wheel diodes of IGBT are injected to Converter DC-side.
Usually there are two types of methods for limiting short-circuit current in the prior art.First method is by increasing on power module
Device.One group of bidirectional thyristor switch in parallel, DC line occur on each power module of modularization multi-level converter
When instantaneity short trouble, it is latched the control pulse of all power cells, while triggering all bidirectional thyristor switch conductions,
Short dot disappears after making DC line short dot natural arc extinguishing.After it is zero to detect DC line short circuit current, control is all
Two-way brilliant lock switch OFF, then open the control pulse of all power cells, transverter made to put into operation again.This side
Method is for inhibiting first part's short circuit current, but the shortcomings that this method is the increase in cost, increases each power module
The cost of element, or even one times of former semibridge system modularization multi-level converter cost can be reached, for Practical Project
It is heavy financial burden.
The method of second of limiting short-circuit current is in the way of increase control strategy to semibridge system mould in the prior art
Block multilevel converter short circuit current is limited, and by being zero by DC bus-bar voltage control, reaches controlled in transverter
And commutation system does not pass through the purpose of direct-current short circuit failure in the state of off-grid, and it is straight to be particularly suitable for direct current overhead transmission line transmission etc.
Flow the higher occasion of failure rate.Basic principle is to overturn DC bus-bar voltage rapidly after detecting direct-current short circuit electric current to inhibit short
Road electric current, after in current drops to normal range (NR), control DC bus-bar voltage is zero, maintains the output of exchange side reactive power；
After direct-current short circuit Failure elimination, DC bus-bar voltage is promoted to rated value, restores active transmission.In control structure, capacitance is added
Voltage controls closed loop, to ensure that the capacitance voltage during direct-current short circuit failure is stablized.This method is for inhibiting second part short
Road electric current, but the shortcomings that this method is to keep the control mode of semibridge system modularization multi-level converter more complicated, is extended
The calculating time of semibridge system modularization multi-level converter controller, when failure occurs, it may appear that longer logic judgment and
Delay, is unfavorable for the safety of semibridge system modularization multi-level converter equipment.Since the influence of first part in short circuit current is remote
Higher than second part, therefore, this method can not inhibit first part's short circuit current.
Utility model content
In order to solve in the prior art, it can not effectively inhibit the short circuit current in flexible direct current power transmission system, this practicality new
Type embodiment provides a kind of flexible direct current power transmission system, and the system comprises transformer, transverter and mutual reactors；
The mutual reactor includes upper bridge arm mutual reactor and lower bridge arm mutual reactor, wherein the upper bridge arm
Mutual reactor is connected by Same Name of Ends with the connection at different name end with lower bridge arm mutual reactor, the Same Name of Ends and the different name
The tie point at end is grid entry point；
One end of the transformer is connect with AC network, and the other end is connect with the grid entry point；
The transverter includes three phase elements, and the phase element includes upper bridge arm and lower bridge arm, the mutual reactor
It is connected between the upper bridge arm and the lower bridge arm.
The utility model is by using mutual reactor, when generating short circuit current, the induction opposite by generating direction
Voltage can effectively inhibit short circuit current in not increase system while device.Thus reach cost-effective, and in nothing
In the case of needing complex control strategy, effective limiting short-circuit current ensures system safety.
Description of the drawings
In order to illustrate the embodiment of the utility model or the technical proposal in the existing technology more clearly, below will be to embodiment
Attached drawing needed in description is briefly described, it should be apparent that, the accompanying drawings in the following description is only that this practicality is new
Some embodiments of type for those of ordinary skill in the art without having to pay creative labor, can be with
Obtain other attached drawings according to these attached drawings.
Fig. 1 is a kind of structural schematic diagram of flexible direct current power transmission system of the utility model embodiment；
Fig. 2A is current direction schematic diagram when a kind of flexible direct current power transmission system of the utility model embodiment works normally；
Current direction schematic diagram when Fig. 2 B are a kind of flexible direct current power transmission system abnormal work of the utility model embodiment；
Fig. 3 is a kind of analogous diagram of flexible direct current power transmission system of the utility model embodiment.
Specific implementation mode
The utility model embodiment provides a kind of flexible direct current power transmission system.
The following will be combined with the drawings in the embodiments of the present invention, carries out the technical scheme in the embodiment of the utility model
Clearly and completely describe, it is clear that the described embodiments are only a part of the embodiments of the utility model, rather than whole
Embodiment.Based on the embodiments of the present invention, those of ordinary skill in the art are without creative efforts
The every other embodiment obtained, shall fall within the protection scope of the present invention.
It is a kind of structural schematic diagram of flexible direct current power transmission system of the utility model embodiment as shown in Figure 1.As shown in the figure
Flexible direct current power transmission system includes transformer T, transverter and mutual reactor；
The mutual reactor includes upper bridge arm mutual reactor L1With lower bridge arm mutual reactor L2, wherein the upper bridge
Arm mutual reactor L1With lower bridge arm mutual reactor L2It is connected with the connection at different name end by Same Name of Ends, tie point a.Specifically
Can be upper bridge arm mutual reactor L when implementation1Same Name of Ends and lower bridge arm mutual reactor L2Different name end be connected, can also
It is upper bridge arm mutual reactor L1Different name end and lower bridge arm mutual reactor L2Same Name of Ends be connected.
One end of the transformer T is connect with AC network, and the other end is connect with the grid entry point a；
The transverter includes three phase elements, and each phase element includes upper bridge arm 11 and lower bridge arm 12, mutual reactor
It is connected between the upper bridge arm 11 and the lower bridge arm 12.
In the present embodiment, for Fig. 1 by taking the phase in grid side AC three-phase as an example, transverter as shown in the figure should share three
Phase corresponds respectively to the three-phase of alternating current.Wherein, grid side alternating current is changed into direct current through transformer T, then by transverter
Electricity output.For transverter there are three phase element, the point that each phase element is connect with alternating current side is grid entry point, grid-connected as shown in the figure
It is the upper bridge arm 11 of transverter phase element on the upside of point a, is the lower bridge arm 12 of transverter phase element on the downside of grid entry point a.Coupling reactance
Device includes upper bridge arm mutual reactor L1With lower bridge arm mutual reactor L2, upper bridge mutual reactor L1It is mutually single to be connected to transverter
11 downside of bridge arm, lower bridge mutual reactor L in member2It is connected to 12 upside of transverter phase element lower bridge arm.L1With L2Pass through Same Name of Ends
It is connected with the connection at different name end, is as shown in the figure L1Different name end and L2Same Name of Ends connection, L1With L2Between be grid entry point a.
Wherein, Fig. 2A is that current direction when a kind of flexible direct current power transmission system of the utility model embodiment works normally shows
It is intended to.In normal work, grid side alternating current passes through the flow direction after grid entry point at flexible DC power transmission station as shown in the figure.From figure
As can be seen that flow directions of the electric current I after grid entry point on upper and lower bridge arm mutual reactor is on the contrary, according to upper and lower bridge arm coupling reactance
Existing coupling, such as following formula between device：
In formula (1), M is the mutual inductance of upper and lower bridge arm mutual reactor, u1With i1For upper bridge arm mutual reactor L1Sense
Answer voltage and electric current, u2With i2For upper bridge arm mutual reactor L2Induced voltage and electric current.Due to i1With i2Direction it is opposite, big
When small equal, u1With u2Also direction is opposite, equal in magnitude, therefore u1With u2Mutually adduction be zero, i.e., upper and lower bridge arm and voltage not
It is impacted.It is possible thereby to learn, in system worked well, the equivalent inductance value of upper and lower bridge arm mutual reactor is：
L=L1+L2-2M (2)
It can thus be seen that when system is in normal work, mutual reactor upstream is excessively equal in magnitude, the opposite electricity in direction
Stream.It is produced with lower bridge arm mutual reactor upstream overcurrent in the induced voltage direction that upper bridge arm mutual reactor upstream overcurrent generates
Raw induced voltage direction is on the contrary, the two is cancelled out each other.Therefore, mutual reactor is operated under the normal pattern of system, reactance
Device inductance value is smaller, does not influence the normal operation of transverter.
Current direction when flexible direct current power transmission system abnormal work a kind of for the utility model embodiment as shown in Figure 2 B
Schematic diagram, flexible DC power transmission station as shown in the figure is in abnormal work, i.e., live part and the improper connection in ground, power grid in system
Top-cross galvanic electricity passes through the flow direction after grid entry point.It can be seen from the figure that short circuit current I1It is coupled in upper and lower bridge arm after grid entry point
Flowing on reactor is identical, according to existing coupling relational expression (1) between upper and lower bridge arm mutual reactor, can obtain
Go out, when system exception works, the equivalent inductance value of upper and lower bridge arm mutual reactor is：
L=L1+L2+2M (3)
When system exception works, the size of current approximately equal on mutual reactor, direction is identical.Upper bridge arm coupling electricity
The induced voltage side that the induced voltage direction that anti-device upstream overcurrent generates is generated with lower bridge arm mutual reactor upstream overcurrent
To identical, with short circuit current I1Direction is on the contrary, play the role of inhibiting short circuit current.In addition, from formula (3) as can be seen that coupling
When closing reactor to be operated in system exception being under pattern, reactor inductance value is larger, can be carried out to the short circuit current in system
Limitation.
As one embodiment of the utility model, the system also includes start-up resistor R1, the start-up resistor series connection
Between the transformer T and the grid entry point a.
In the present embodiment, one circuit breaker Q F of start-up resistor R1 parallel connectionsR, when needing start-up resistor R1 to exit, it is closed
Short-circuiting device QFR, bypass start-up resistance R1.
As one embodiment of the utility model, the system also includes direct current reactor LZ, the AC network is defeated
The alternating current entered is converted to direct current, the direct current reactor L through transverterZIt is connected to the transverter and the direct current
Between positive or negative pole.
In the present embodiment, as shown in Figure 1, direct current reactor LZIt is connected between transverter and the anode of direct current,
In, U indicates the voltage of the direct current of system output, direct current reactor LZIt can play the role of protecting DC line.
As one embodiment of the utility model, the system also includes AC circuit breaker QF1, are connected to the transformation
Between device T and the AC network, the input for controlling alternating current.
In the present embodiment, AC circuit breaker QF1 is closed, and grid side alternating current is input to system, and the system of being achieved in opens
It is dynamic.
As one embodiment of the utility model, the system also includes current-limiting reactor LS, be series at transformer T with
Between the grid entry point a.
In the present embodiment, the system also includes current limliting branch 20, the current limliting branch 20 includes power electronic devices
21 are connected in series in capacitor 22, the capacitor 22 between the power electronic devices 21 and ground, the current limliting branch 20
It is connected in parallel in the grid entry point a and the current-limiting reactor LSBetween.
Wherein, when short circuit occurs for system, mutual reactor can effectively inhibit first part short circuit current I1, i.e. capacitance
The electric current that device is discharged by IGBT.When short trouble occurs in system, while second part short circuit current is will produce, that is, handed over
Galvanic electricity net side is former by what is injected to Converter DC-side with the antiparallel fly-wheel diodes of IGBT in reactor and power module
Hinder electric current, second part short circuit current flow direction is referred to second part short circuit current I shown in Fig. 2 B2.The current limliting branch
20 and current-limiting reactor LSIt is respectively positioned on exchange side, it, will be electric by power electronic devices 21 in parallel in system normal operation
An idle and concatenated current-limiting reactor L for container 22SIt offsets, maintains the voltage stabilization of three-phase AC grid.In system event
In the case of barrier, by being latched power electronic devices 21 in parallel, the nothing for the capacitor 22 that cut-out power electronic devices 21 concatenates
Work(is supplied, and current-limiting reactor L is madeSPlay limiting short-circuit current I2Effect.Wherein, current electrons device 21 can be, for example,
The power electronic devices such as IGBT, metal-oxide-semiconductor, but it is not limited thereto system.
Mutual reactor is used by Tthe utility model system, when generating short circuit current, opposite by generation direction
Induced voltage can effectively inhibit short circuit current in not increase system while device.Thus reach cost-effective, and
Without complex control strategy, effective limiting short-circuit current ensures system safety.
It is illustrated in figure 3 a kind of analogous diagram of flexible direct current power transmission system of the utility model embodiment.System is in 0.05s
There is short trouble, shown in figure is first part's short circuit current curve, and solid line is the short circuit current curve of ordinary reactors,
Dotted line is the short circuit current curve of mutual reactor.Obviously, the short circuit of the short-circuit current value and ordinary reactors of mutual reactor
Between current value, highest can differ 10KA or so.Therefore, mutual reactor can significantly inhibit short circuit current, while not increase
Device in adding system reaches cost-effective, and without complex control strategy, effective limiting short-circuit current, protects
Card system safety.
Particular embodiments described above has carried out into one the purpose of this utility model, technical solution and advantageous effect
Step is described in detail, it should be understood that the foregoing is merely specific embodiment of the utility model, is not used to limit this
The protection domain of utility model, within the spirit and principle of the utility model, any modification for being made, changes equivalent replacement
Into etc., it should be included within the scope of protection of this utility model.
Claims (7)
1. a kind of flexible direct current power transmission system, which is characterized in that the system comprises transformer, transverter and mutual reactors；
The mutual reactor includes upper bridge arm mutual reactor and lower bridge arm mutual reactor, wherein the upper bridge arm coupling
Reactor is connected by Same Name of Ends with the connection at different name end with lower bridge arm mutual reactor, the Same Name of Ends and the different name end
Tie point is grid entry point；
One end of the transformer is connect with AC network, and the other end is connect with the grid entry point；
The transverter includes three phase elements, and the phase element includes upper bridge arm and lower bridge arm, the mutual reactor connection
Between the upper bridge arm and the lower bridge arm.
2. system according to claim 1, which is characterized in that the system also includes start-up resistor, the start-up resistor
It is series between the transformer and the grid entry point.
3. system according to claim 1, which is characterized in that the transverter is modularization multi-level converter, described
Upper bridge arm is composed in series with the lower bridge arm by multiple Modularized multi-level converter sub-modules.
4. system according to claim 1, which is characterized in that the system also includes direct current reactor, the alternating current
The alternating current of net input is converted to direct current through transverter, and the direct current reactor is connected to the transverter and the direct current
Positive or negative pole between.
5. system according to claim 1, which is characterized in that the system also includes AC circuit breaker, be connected to described
Between transformer and the AC network, the input for controlling alternating current.
6. system according to claim 1, which is characterized in that the system also includes current-limiting reactors, are series at transformation
Between device and the grid entry point.
7. system according to claim 6, which is characterized in that the system also includes current limliting branch, the current limliting branch
Including power electronic devices and capacitor, the capacitor is connected in series between the power electronic devices and ground, the limit
Stream branch circuit parallel connection is connected between the grid entry point and the current-limiting reactor.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201820585762.6U CN208063039U (en) | 2018-04-24 | 2018-04-24 | A kind of flexible direct current power transmission system |
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| CN201820585762.6U CN208063039U (en) | 2018-04-24 | 2018-04-24 | A kind of flexible direct current power transmission system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108400701A (en) * | 2018-04-24 | 2018-08-14 | 国网冀北电力有限公司电力科学研究院 | A kind of flexible direct current power transmission system |
| CN110492516A (en) * | 2019-07-29 | 2019-11-22 | 南方电网科学研究院有限责任公司 | A kind of extra-high voltage Multi-end flexible direct current transmission converter station system and its control method |
-
2018
- 2018-04-24 CN CN201820585762.6U patent/CN208063039U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108400701A (en) * | 2018-04-24 | 2018-08-14 | 国网冀北电力有限公司电力科学研究院 | A kind of flexible direct current power transmission system |
| CN110492516A (en) * | 2019-07-29 | 2019-11-22 | 南方电网科学研究院有限责任公司 | A kind of extra-high voltage Multi-end flexible direct current transmission converter station system and its control method |
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