CN107994597A - High-voltage large-capacity overhead line flexible direct current power transmission system fault ride-through method - Google Patents
High-voltage large-capacity overhead line flexible direct current power transmission system fault ride-through method Download PDFInfo
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- CN107994597A CN107994597A CN201711002865.1A CN201711002865A CN107994597A CN 107994597 A CN107994597 A CN 107994597A CN 201711002865 A CN201711002865 A CN 201711002865A CN 107994597 A CN107994597 A CN 107994597A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
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- Direct Current Feeding And Distribution (AREA)
- Supply And Distribution Of Alternating Current (AREA)
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Abstract
The present invention relates to a kind of high-voltage large-capacity overhead line flexible direct current power transmission system fault ride-through method, belong to flexible direct current system error protection field.The output voltage characteristic of MMC under topological structure, active power and the flexible control characteristic of reactive power and blocking by analyzing LCC MMC series hybrid DC transmission systems, Collaborative Control based on LCC and MMC, the control method of high-voltage large-capacity overhead line flexible direct current power transmission system alternating current-direct current fault traversing is given, and then realizes the safe and stable operation of system.Project cost is minimum under the same conditions for LCC MMC series hybrid direct current transportation topology in the present invention, while removes DC Line Fault using LCC, without extras such as configuring direct current breaker and DC damping circuits, further improves the economy of system.
Description
Technical field
The present invention relates to overhead line flexible direct current power transmission system error protection field, more particularly to a kind of high-voltage large-capacity frame
Ceases to be busy flexible direct current power transmission system fault ride-through method.
Background technology
In recent years, China's energy development accelerates to shift to western and the north, and the distance of Energy Base and load center is more next
More remote, long-distance and large-capacity power transmission becomes the fundamental driving force of China's power network development.Flexible DC power transmission can effectively improve cleaning energy
The grid connection efficiency of source power generation, alleviates voltage fluctuation and is impacted caused by power grid, is extensive clean energy resource base access power grid
Effective technology means.When applied to long-distance and large-capacity power transmission occasion, the economy for line construction considers, between current conversion station
Connection will use overhead transmission line.Relative to the direct current cables being currently mainly used, the DC Line Fault incidence of overhead transmission line is higher,
Therefore current conversion station itself (or relying on other to protect equipment) should possess DC Line Fault Scavenging activity.Equally examined for economy
Consider, current conversion station is often using the half-bridge submodule (H-MMC) for not possessing DC Line Fault locking function, because it is adopted under the same conditions
Power semiconductor number is minimum, thus with minimum cost and steady-state loss.In this case, for H-
The DC Line Fault of MMC is removed and is typically based on following three kinds of schemes：
1) faulty line is directly disconnected to remove fault current using dc circuit breaker；
2) mechanical switch in tripping current conversion station exchange exit, to cut off energy feed-in way of the AC system to trouble point
Footpath, while utilize the decay of DC damping circuit acceleration disturbance electric current；
3) Hybrid HVDC structure is used, current conversion station is possessed fault clearance ability in itself.
Method 1) the most effectively, but it still lacks the practical operating experiences in engineering at present.Mode 2) it is the most economical,
The flexible DC power transmission engineering that the country has put into operation at present uses this method.However, since mechanical switch responsiveness is slow, system
Overcurrent is serious under DC Line Fault, and current conversion station, which needs to use, possesses the power device compared with high throughflow ability；In addition, mechanical switch
Slow motion will cause system recovery time to be grown, this is also unfavorable for the transient stability of ac and dc systems.Mode 3) it is substantially to utilize
The transverter of mixed topology structure with fault ride-through capacity substitutes dc circuit breaker, such as rectification side using LCC, inverter side
Using the LCC-F-MMC of F-MMC, rectification side using LCC, inverter side using C-MMC LCC-C-MMC and rectification side using LCC,
Inverter side is using H-MMC and in the LCC-Diode-MMC of inversion side outlet installing diode.The major defect of such topological structure
It is, since the DC voltage response speed of inverter side MMC is slow, likely results in DC current under rectification side AC fault and break
Stream.
In conclusion with the popularization and application of high-voltage large-capacity flexible direct current power transmission system overhead line, its system failure is worn
Technical barrier urgently to be resolved hurrily.Above-mentioned three kinds of schemes all can not effectively realize high-voltage large-capacity overhead line flexible DC power transmission
The error protection of system.Therefore, it is necessary to carry out relevant research, seek a kind of effective fault ride-through method.
The content of the invention
It is an object of the invention to provide a kind of high-voltage large-capacity overhead line flexible direct current power transmission system fault ride-through method,
Solves the above problem existing in the prior art, pole while overhead line flexible direct current power transmission system safe and stable operation is ensured
Big reduces system cost.The present invention is based on LCC and modularization multi-level converter (Modular multilevel
Converter, MMC) Hybrid HVDC topology project cost is minimum under the same conditions, while remove direct current using LCC
Failure, without extras such as configuring direct current breaker and DC damping circuits, can further lift topological economy.Direct current
Fault clearance and recovery process, which mainly include fault detect, MMC lockings and LCC, forces phase shift, goes free and restart.
The above-mentioned purpose of the present invention is achieved through the following technical solutions：
High-voltage large-capacity overhead line flexible direct current power transmission system fault ride-through method, flexible direct current power transmission system topology are each
Pole is in series by 12 pulsation LCC and modular multilevel change of current valve group (Bank of MMCs, MMCB), and wherein MMCB is low
Hold transverter group (DC voltage is relatively low), LCC is high-end transverter group (DC voltage is higher), MMCB by some MMC simultaneously
Connection is formed, and submodule uses HBSM, to overcome the limitation of IGBT maximum current capacities at this stage, for the surge under fault restriction
Electric current, each pole exit of current conversion station are configured with smoothing reactor；According to the topological structure and main wiring mode of system, failure
Traversing method comprises the following steps：
(1) failure subregion is carried out to system, and analyzes its behavioral characteristics；
(2) each current conversion station detection judges whether system breaks down, and is that then order performs step (3), otherwise continues
Detection；
(3) determine system failure type, and carry out fault location；
(4) fault type and fault location in step (3), selection perform step (4A), step (4B) and step
(4C)；
When (4A) rectification side AC system breaks down, two benches standby Given current controller is taken；First stage is to pass through
The output DC voltage of lifting rectification side MMCB maintains the DC voltage of rectification side entirety；Second stage is by reducing inversion
The DC voltage of side LCC output maintains DC current；
When (4B) inverter side AC system breaks down, the LCC of rectification side and inverter side needs teamwork, rectification side
LCC will increase Trigger Angle to limit the increase of DC current；Inverter side LCC needs to be switched to from constant DC voltage control to determine blow-out
Angle controls, to reduce the risk of commutation failure in transient process；
When (4C) DC line breaks down, using the Collaborative Control of rectification side LCC and MMC, i.e. rectification side LCC is using strong
Phase shift processed, while the MMC of rectification side and inverter side all lockings, pass through the DC voltage for forcing phase shift rectification side LCC to export
Absolute value is more than the amplitude of MMC valve side non-loaded line potential, realizes effective suppression of short circuit current flow；
(5) selection performs step (5A) and step (5B)；
(5A) waits a bit of time after step (4A) and step (4B) fault clearance, and both sides current conversion station is switched to just
Normal control model is completed AC fault and is passed through；
(5B) continues to keep control action 0.2s after step (4C) fault clearance, and that realizes trouble point goes free process,
After insulation recovery, while the MMC of rectification side and inverter side is unlocked, after the Trigger Angle of LCC linearly moves to steady-state value, be switched to
Control model under stable state is completed DC Line Fault and is passed through.
The main wiring mode of LCC and MMC series hybrid flexible direct current power transmission systems is the bipolar mode of connection, to reduce event
The power rush for sending receiving end AC system to bear during barrier, improves power supply reliability.
Failure subregion described in step (1) is：High-voltage large-capacity overhead line flexible direct current power transmission system failure is divided into
Three rectification side AC fault, DC side failure and inverter side AC fault regions.
The direct current voltage absolute value of rectification side LCC outputs described in step (4C) is more than the width of MMC valve side non-loaded line potential
Value, meets following relation：
Wherein, αFRThe Trigger Angle after phase shift, U are forced for LCCRLDC voltage is exported for LCC under stable state, E is MMC valve side
Non-loaded line potential.
The present invention is by analyzing the topological structures of LCC-MMC series hybrid DC transmission systems, active power and idle
The output voltage characteristic of MMC, based on the Collaborative Control of LCC and MMC, gives height under the flexible control characteristic of power and blocking
The control method of large capacity overhead line flexible direct current power transmission system alternating current-direct current fault traversing is pressed, and then realizes the safety and stability of system
Operation.Project cost is minimum under the same conditions for LCC-MMC series hybrid direct current transportation topology in the present invention, utilizes at the same time
LCC removes DC Line Fault, without extras such as configuring direct current breaker and DC damping circuits, further improves system
Economy.
The beneficial effects of the present invention are：
(1) LCC-MMC series hybrid flexible direct current power transmission systems of the invention combine the advantage of LCC and MMC, can be only
Vertical control active power and reactive power, have operational flexibility, while reduce manufacture cost and running wastage, wherein MMC
Capacity problem can be solved by transverter parallel connection, this is adapted with existing manufacturing capacity.
(2) the fault ride-through method of the invention system under rectification side AC fault will not stop, inverter side exchange
Under failure, even if commutation failure occurs, system remains to keep certain power delivering capability, and for the short of DC line fault
Road electric current, can be by controlling the action of transverter in itself to remove, it is not necessary to which additional other equipment, wears improving the system failure
More ability while reduce investment cost.It is highly practical.
Brief description of the drawings
Attached drawing described herein is used for providing a further understanding of the present invention, forms the part of the application, this hair
Bright illustrative example and its explanation is used to explain the present invention, does not form inappropriate limitation of the present invention.
Fig. 1 is the bipolar system LCC-MMC series hybrid high-voltage large-capacity overhead line flexible direct current power transmission systems of the present invention
Structure diagram；
Fig. 2, Fig. 3, Fig. 4 are the MMCB topology diagrams of the present invention；
Fig. 5 is the flow chart of the fault ride-through method based on LCC and MMC Collaborative Controls of the present invention；
Fig. 6 is directed to the DC current two benches standby control block diagram (first stage when being the rectification side AC fault of the present invention
The control mode of output DC voltage is lifted by rectification side MMCB)；
Fig. 7 is directed to DC current two benches standby control block diagram (second stage when being the rectification side AC fault of the present invention
The DC voltage exported by inverter side LCC maintains the control mode of DC current)；
The constant DC voltage control that gamma kick is determined with standby that Fig. 8 is the inverter side AC fault LCC of the present invention
Block diagram；
Fig. 9 is the system emulation figure (rectification side AC fault simulation result figure) of the present invention；
Figure 10 is the system emulation figure (inverter side AC fault simulation result figure) of the present invention；
Figure 11 is the system emulation figure (DC Line Fault simulation result figure) of the present invention.
Embodiment
The detailed content and its embodiment of the present invention is further illustrated below in conjunction with the accompanying drawings.
Referring to shown in Fig. 1 to Figure 11, the present invention is directed to high-voltage large-capacity overhead line flexible direct current power transmission system fault traversing
The bipolar system LCC-MMC series hybrids system structure of design is as shown in Figure 1, each pole is connected by 12 pulsation LCC and MMCB
Form, wherein MMCB be low side transverter group (DC voltage is relatively low), LCC be high-end transverter group (DC voltage compared with
It is high).The structure of MMCB is as shown in Fig. 2, it can be made of some MMC parallel connections, to overcome IGBT maximum current capacities at this stage
Limitation；To be limited if there is no IGBT through-current capabilities, it is in parallel without MMC.For the surge current under fault restriction, change
The each pole exit in stream station is configured with smoothing reactor.
As shown in figure 3, MMC is made of 6 bridge arms, each bridge arm is composed in series by bridge arm inductance and N number of submodule, same
Two bridge arms of phase form a phase element.Submodule uses HBSM, its structure is as shown in Figure 4.In general, H-MMC is difficult to pass through
Transverter itself action processing DC Line Fault, reason are after locking that AC system is remained to by anti-paralleled diode to trouble point
Injection Current.High-voltage large-capacity overhead line flexible direct current power transmission system fault ride-through method provided by the invention is then to pass through LCC
Alternating current-direct current failure is handled with the Collaborative Control of MMC, realizes step as shown in figure 5, specifically including：
(1) high-voltage large-capacity overhead line flexible direct current power transmission system failure is divided into rectification side AC fault, inverter side
Three regions of AC fault and DC side failure, and analyze its behavioral characteristics；
(2) each current conversion station persistently detects the electrical quantity such as position alternating current-direct current side bus voltage and electric current, on this basis,
Judge whether system breaks down, be that then order performs step (3), otherwise continue to detect；
(3) according to the behavioral characteristics of detected electrical quantity, system failure type is determined, and carry out fault location；
(4) fault type in step (3) and positioning, selection perform step (4A), step (4B) and step (4C)；
When (4A) rectification side AC system breaks down, two benches standby Given current controller is taken.First stage is to pass through
The output DC voltage of lifting rectification side MMCB maintains the DC voltage of rectification side entirety, as shown in Figure 6.The stage control
In, the DC voltage maximal increment Δ U of MMCBRMIt is conservative to be taken as 0.1pu, trigger the current deviation Δ I of the controld1It is arranged to mesh
The 5% of scale value, avoids conflicting with the constant DC current control device under stable state.Second stage is by reducing inverter side LCC outputs
DC voltage maintain DC current, as shown in Figure 7；
When (4B) inverter side AC system breaks down, the LCC of rectification side and inverter side needs teamwork, rectification side
LCC will increase Trigger Angle to limit the increase of DC current；Inverter side LCC needs to be switched to from constant DC voltage control to determine blow-out
Angle controls, as shown in figure 8, to reduce the risk of commutation failure in transient process；
When (4C) DC line breaks down, using the Collaborative Control of rectification side LCC and MMC, i.e. rectification side LCC is using strong
Phase shift processed, while the MMC of rectification side and inverter side all lockings, pass through the DC voltage for forcing phase shift rectification side LCC to export
Absolute value is more than the amplitude of MMC valve side non-loaded line potential, realizes effective suppression of short circuit current flow.Rectification side LCC is in the steady state
Trigger Angle is usually 15 °, to meet the voltage relationship, is had
Wherein, αFRThe Trigger Angle after phase shift, U are forced for LCCRLDC voltage is exported for LCC under stable state, E is MMC valve side
Non-loaded line potential, its value can be estimated asIt is further represented as
It is k to define the ratio between LCC and MMC DC voltages under stable stateLM, kLMIt should then meet
It is apparent from αFRK at=135 °LM>0.966, αFRK at=150 °LM>0.789, this explanation takes kLM=1.0 can tie in topology
Ensure that DC Line Fault is removed efficiently on structure, i.e. locking MMC after DC Line Fault generation, while LCC Trigger Angles force phase shift extremely
135 °~150 °.
(5) selection performs step (5A) and step (5B)；
(5A) waits a bit of time after the step (4A) and step (4B) fault clearance, and both sides current conversion station is switched
AC fault is completed to normal control mode to pass through；
(5B) continues to keep above-mentioned control action 0.2s, realizes going for trouble point after the step (4C) fault clearance
Free process, after insulation recovery, while unlocks the MMC of rectification side and inverter side, the Trigger Angle of LCC is linearly moved to stable state
Value, whole start-up course takes 0.2s, and after the completion of restarting, the control model completion DC Line Fault being switched under stable state passes through.
The foregoing is merely the preferred embodiment of the present invention, it is not intended to limit the invention, for the technology of this area
For personnel, the invention may be variously modified and varied.All any modification, equivalent substitution, improvement and etc. made for the present invention,
It should all be included in the protection scope of the present invention.
Claims (4)
- A kind of 1. high-voltage large-capacity overhead line flexible direct current power transmission system fault ride-through method, it is characterised in that：Flexible direct current is defeated The each pole of electric system topology is in series by 12 pulsation LCC and MMCB, and wherein MMCB is low side transverter group, and LCC is high-end Transverter group, MMCB are made of some MMC parallel connections, and submodule uses HBSM, to overcome IGBT maximum current capacities at this stage Limitation, for the surge current under fault restriction, each pole exit of current conversion station is configured with smoothing reactor；Fault traversing side Method comprises the following steps：(1) failure subregion is carried out to system, and analyzes its behavioral characteristics；(2) each current conversion station detection judges whether system breaks down, and is that then order performs step (3), otherwise continues to detect；(3) determine system failure type, and carry out fault location；(4) fault type and fault location in step (3), selection perform step (4A), step (4B) and step (4C)；When (4A) rectification side AC system breaks down, two benches standby Given current controller is taken；First stage is to pass through lifting The output DC voltage of rectification side MMCB maintains the DC voltage of rectification side entirety；Second stage is by reducing inverter side The DC voltage of LCC outputs maintains DC current；When (4B) inverter side AC system breaks down, the LCC of rectification side and inverter side needs teamwork, and rectification side LCC will Increase Trigger Angle to limit the increase of DC current；Inverter side LCC, which needs to be switched to from constant DC voltage control, determines the control of blow-out angle System, to reduce the risk of commutation failure in transient process；When (4C) DC line breaks down, using the Collaborative Control of rectification side LCC and MMC, i.e. rectification side LCC is moved using pressure Phase, while the MMC of rectification side and inverter side all lockings, by forcing the DC voltage that phase shift rectification side LCC is exported absolute Value realizes effective suppression of short circuit current flow more than the amplitude of MMC valve side non-loaded line potential；(5) selection performs step (5A) and step (5B)；(5A) waits 0.5s after step (4A) and step (4B) fault clearance, and both sides current conversion station is switched to normal control mode AC fault is completed to pass through；(5B) continues to keep control action 0.2s after step (4C) fault clearance, and that realizes trouble point goes free process, treats absolutely After edge recovers, while the MMC of rectification side and inverter side is unlocked, after the Trigger Angle of LCC linearly moves to steady-state value, be switched to stable state Under control model complete DC Line Fault pass through.
- 2. high-voltage large-capacity overhead line flexible direct current power transmission system fault ride-through method according to claim 1, its feature It is：The main wiring mode of LCC and MMC series hybrid flexible direct current power transmission systems is the bipolar mode of connection, to reduce failure Period send the power rush that receiving end AC system is born, and improves power supply reliability.
- 3. high-voltage large-capacity overhead line flexible direct current power transmission system fault ride-through method according to claim 1, its feature It is：Failure subregion described in step (1) is：High-voltage large-capacity overhead line flexible direct current power transmission system failure is divided into rectification Three side AC fault, DC side failure and inverter side AC fault regions.
- 4. high-voltage large-capacity overhead line flexible direct current power transmission system fault ride-through method according to claim 1, its feature It is：The direct current voltage absolute value of rectification side LCC outputs described in step (4C) is more than the amplitude of MMC valve side non-loaded line potential, Meet following relation：Wherein, αFRThe Trigger Angle after phase shift, U are forced for LCCRLDC voltage is exported for LCC under stable state, E is MMC valve side non-loaded line Potential.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108574286A (en) * | 2018-05-09 | 2018-09-25 | 华中科技大学 | The idle work optimization and fault ride-through method of mixed type transverter MMC-PLUS |
| CN108879625A (en) * | 2018-07-19 | 2018-11-23 | 南京南瑞继保电气有限公司 | A kind of parallel connection multiterminal extra-high voltage direct-current transmission valve unit protection action processing method |
| CN114884112A (en) * | 2022-04-21 | 2022-08-09 | 浙江大学 | Receiving end alternating current fault ride-through control method of hybrid cascade direct current transmission system |
| CN115207959A (en) * | 2022-09-13 | 2022-10-18 | 东南大学溧阳研究院 | Offshore wind power direct-current power transmission system based on hybrid series connection of LCC and full-bridge MMC-STATCOM |
| US11616369B2 (en) * | 2019-11-07 | 2023-03-28 | State Grid Jiangsu Electric Power Co., Ltd. | Control method for a parallel MMC unit of a LCC-MMC hybrid cascade converter station |
-
2017
- 2017-10-24 CN CN201711002865.1A patent/CN107994597A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108574286A (en) * | 2018-05-09 | 2018-09-25 | 华中科技大学 | The idle work optimization and fault ride-through method of mixed type transverter MMC-PLUS |
| CN108879625A (en) * | 2018-07-19 | 2018-11-23 | 南京南瑞继保电气有限公司 | A kind of parallel connection multiterminal extra-high voltage direct-current transmission valve unit protection action processing method |
| US11616369B2 (en) * | 2019-11-07 | 2023-03-28 | State Grid Jiangsu Electric Power Co., Ltd. | Control method for a parallel MMC unit of a LCC-MMC hybrid cascade converter station |
| CN114884112A (en) * | 2022-04-21 | 2022-08-09 | 浙江大学 | Receiving end alternating current fault ride-through control method of hybrid cascade direct current transmission system |
| CN115207959A (en) * | 2022-09-13 | 2022-10-18 | 东南大学溧阳研究院 | Offshore wind power direct-current power transmission system based on hybrid series connection of LCC and full-bridge MMC-STATCOM |
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