CN106918759A - A kind of MMC direct-current short circuits fault detection method and device - Google Patents
A kind of MMC direct-current short circuits fault detection method and device Download PDFInfo
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
Abstract
The present invention relates to a kind of MMC direct-current short circuits fault detection method and device, current conversion station is divided into master station mode and slave station mode by the present invention, one current conversion station of selection is used as main website, other current conversion stations are used as slave station, main website gradually lifting DC voltage, the difference that slave station passes through DC current value of feedback and DC current reference value, the DC voltage of tracking recovery main website, when the DC voltage of main website lifting is T1 continuously less than the time of the first setting value, judge that direct-current short circuit failure is still present.The present invention is communicated between need not being stood in whole process fault detection, other testing equipments need not be increased, it is the detection for being capable of achieving short trouble only by original DC voltage, current sensor, for the not fully erased rear lifting DC voltage of direct-current short circuit failure provides Reliable guarantee, and the problem that second short circuit, submodule repid discharge are bypassed and converter blocking trips is not resulted in.
Description
Technical field
The invention belongs to technical field of direct current power transmission, and in particular to a kind of MMC direct-current short circuits fault detection method and device.
Background technology
At present, the application with the development and Power Electronic Technique of all-controlling power electronics device in power system, base
It is increasingly subject to pay attention in the Technology of HVDC based Voltage Source Converter of voltage source converter.Modularization multi-level converter (Modular
Multilevel converter, MMC) it is one kind in the transverter of flexible direct current power transmission system applied voltage source, it is by multiple
Submodule is formed by connecting according to certain mode, and transverter is made by controlling the input and excision state of each submodule IGBT groups
The alternating voltage of output approaches sine wave, realizes the high efficiency of transmission of energy.
In traditional modularization multi-level converter, generally using unit based on semibridge system submodule, changed with reducing
Flow the construction cost of device.Conventional half-bridge formula module MMC cannot rapidly be pressed down when direct-current short circuit failure occurs by self-characteristic
Fault current processed, it is necessary to could remove fault current by AC circuit breaker or dc circuit breaker.The shortcoming of the method is：By
It is more long in the response time of AC circuit breaker, may cause to protect the overcurrent damage for causing transverter not in time；Additionally, configuration
Dc circuit breaker can improve the technical requirements to equipment, increase system cost.
In order to solve the above problems, there is scholar to propose to solve the change of current using full-bridge submodule or clamp Shuangzi module MMC
The problem of device overcurrent damage：After short trouble, by rapid locking transverter, using in full-bridge submodule diode it is reverse
Blocking ability suppresses rapidly fault current, realizes the removing of DC Line Fault.But after converter blocking, submodule voltage can be with
Own loss and gradually reduce, be finally bypassed due to undertension, transverter tripping operation, cause flexible direct current power transmission system not
Can from failure fast quick-recovery, increase time for recovering from failure of flexible direct current power transmission system.Therefore, scholar proposes to adopt again
Sufficient amount of full-bridge submodule is added in conventional half-bridge submodule MMC, as shown in figure 1, being exported using full-bridge submodule
The ability of negative level, zero is reduced in the case where maintenance AC is grid-connected by DC voltage, so that suppress fault current rapidly,
Do not realize that DC Line Fault is passed through under blocking.
But, it is necessary to first whether detection direct-current short circuit failure is complete before the method re-establishes DC voltage after a failure
Clear all, otherwise just lifts DC voltage when direct-current short circuit failure is not fully erased, will necessarily cause second short circuit failure, draws
Rise submodule repid discharge be bypassed, converter blocking tripping operation, therefore, only confirm direct-current short circuit failure removed when
Can be boosted.
Therefore, it is highly desirable to propose a kind of safe and efficient direct-current short circuit fault condition detection method, can effectively solves
Certainly the contradiction between zero DC voltage control and dc voltage boost, maintains in DC side without overvoltage and overcurrent, AC
Accurately judge whether direct-current short circuit failure has been removed on the premise of grid-connected and reactive-load compensation, be that DC voltage recovers to carry out standard
It is standby.
The content of the invention
It is an object of the invention to provide a kind of MMC direct-current short circuits fault detection method and device, for solving direct-current short circuit
Second short circuit failure problems caused by DC voltage are just lifted when failure is not fully erased.
In order to solve the above technical problems, the present invention proposes a kind of MMC direct-current short circuits fault detection method, including following methods
Scheme：
Method scheme one, comprises the following steps：
, used as main website, other current conversion stations are used as slave station for one current conversion station of selection；DC voltage is started from scratch by the main website
Lifting, real-time detection DC voltage in lifting process, the slave station according to DC current value of feedback and DC current reference value it
Difference, the DC voltage of synchronized tracking main website；When the DC voltage is T1 continuously less than the time of the first setting value, judge straight
Flow short-circuit failure is still present.
Method scheme two, on the basis of method scheme one, when direct-current short circuit failure is still present, controls the main website
It is zero DC voltage control state.
Method scheme three, on the basis of method scheme one, when the DC voltage is persistently more than or equal to the first setting
When the time of value is T2, judge that direct-current short circuit failure has been removed, main website continues to lift up DC voltage, until being promoted to direct current
Pressure rated value.
Method scheme four, on the basis of method scheme one, the main website, will be described according to the first direct current biasing of setting
DC voltage is started from scratch lifting, when DC voltage is T1 less than the time of the first setting value, judges direct-current short circuit failure still
So exist；First direct current biasing is used to combine the bridge arm voltage that three-phase modulations ripple generates main website.
Method scheme five, on the basis of method scheme one, the slave station joins DC current value of feedback and DC current
After examining value work difference, by proportional controller or pi controller, the second direct current biasing of bridge arm modulation instructions is generated；It is described
Second direct current biasing is used to combine the bridge arm voltage that three-phase modulations ripple generates slave station transverter.
Method scheme six, seven, respectively on the basis of method scheme four, five, the bridge arm voltage calculating formula is as follows：
In formula, work as varmFor main website transverter bridge arm voltage when, Udc_ratedIt is the rated value of DC voltage, k is first straight
Flow the perunit value of biasing, eabcIt is three-phase modulations ripple；Work as varmFor slave station transverter bridge arm voltage when, Udc_ratedIt is DC voltage
Rated value, k is the bigoted perunit value of the second direct current, eabcIt is three-phase modulations ripple.
Method scheme eight, nine, respectively on the basis of method scheme six, seven, when k is the first direct current biasing, k is by instructing
Value krefWith command value kerrAddition is obtained, krefBe gradually risen up to by 0 according to specified slope 1 command value, kerrFor limitation is straight
Flow the command value of electric current.
Method scheme ten, 11, respectively on the basis of method scheme eight, nine, the main website is in lifting process direct current
In pressure, when DC current is more than the upper limit of setting or the lower limit less than setting, first direct current biasing is corrected, by direct current
Flow control is between the upper limit and lower limit.
In order to solve the above technical problems, the present invention also proposes a kind of MMC direct-current short circuits failure detector, including following dress
Put scheme：
Device scheme one, including with lower unit：
Select unit：For selecting a current conversion station as main website, other current conversion stations are used as slave station；
Judging unit：DC voltage is started from scratch lifting, real-time detection direct current in lifting process for the main website
Pressure, the slave station is according to DC current value of feedback and the difference of DC current reference value, the DC voltage of synchronized tracking main website；Work as institute
When stating time of the DC voltage continuously less than the first setting value for T1, judge that direct-current short circuit failure is still present.
Device scheme two, on the basis of device scheme one, also including for when direct-current short circuit failure is still present, controlling
Make the unit that the main website is zero DC voltage control state.
Device scheme three, on the basis of device scheme one, also including for when the DC voltage is persistently more than or waits
When the time of the first setting value being T2, judge that direct-current short circuit failure has been removed, main website continues to lift up DC voltage, until carrying
Rise to the unit of DC voltage rated value.
Device scheme four, on the basis of device scheme one, also including for the main website according to setting the first direct current
Biasing, the DC voltage is started from scratch lifting, when DC voltage is T1 continuously less than the time of the first setting value, judgement
Direct-current short circuit failure is still present；First direct current biasing is used for the list of the bridge arm voltage for combining three-phase modulations ripple generation main website
Unit.
Device scheme five, on the basis of device scheme one, also including for the slave station by DC current value of feedback with
After DC current reference value makees difference, by proportional controller or pi controller, the second of generation bridge arm modulation instructions is straight
Stream biasing；Second direct current biasing is used for the unit of the bridge arm voltage for combining three-phase modulations ripple generation slave station transverter.
Device scheme six, seven, respectively on the basis of device scheme four, five, the bridge arm voltage calculating formula is as follows：
In formula, work as varmFor main website transverter bridge arm voltage when, Udc_ratedIt is the rated value of DC voltage, k is first straight
Flow the perunit value of biasing, eabcIt is three-phase modulations ripple；Work as varmFor slave station transverter bridge arm voltage when, Udc_ratedIt is DC voltage
Rated value, k is the bigoted perunit value of the second direct current, eabcIt is three-phase modulations ripple.
Device scheme eight, nine, respectively on the basis of device scheme six, seven, also including for being the first direct current biasing as k
When, k is by command value krefWith command value kerrAddition is obtained, krefBe gradually risen up to by 0 according to specified slope 1 command value,
kerrTo limit the unit of the command value of DC current.
Device scheme ten, 11, respectively on the basis of device scheme eight, nine, also including DC current control unit：With
In the main website in lifting process DC voltage, when DC current is more than the upper limit of setting or the lower limit less than setting, repair
Just described first direct current biasing, by DC current control between the upper limit and lower limit.
The beneficial effects of the invention are as follows：Current conversion station is divided into master station mode and slave station mode by the present invention, selects a change of current
Stand as main website, other current conversion stations as slave station, main website gradually lifting DC voltage, slave station by DC current value of feedback with it is straight
The difference of current reference value is flowed, tracking recovers the DC voltage of main website, when the DC voltage of main website lifting is continuously less than the first setting
When the time of value is T1, judge that direct-current short circuit failure is still present.The present invention need not be carried out in whole process fault detection
Communicated between standing, it is not necessary to increase other testing equipments, be to be capable of achieving short trouble only by original DC voltage, current sensor
Detection, for lifting DC voltage provides Reliable guarantee after direct-current short circuit failure is not fully erased, and do not result in second short circuit,
The problem that submodule repid discharge is bypassed and converter blocking trips.
Brief description of the drawings
Fig. 1 is half-bridge, the topological structure schematic diagram of the hybrid MMC of full-bridge submodule；
Fig. 2 is the hybrid MMC direct-current short circuits fault detect flow chart of submodule of the invention；
Fig. 3 is main website converter Control block diagram；
Fig. 4 is slave station converter Control block diagram；
Fig. 5 is the control principle drawing of DC current restriction controller；
Fig. 6 is the electrical quantity oscillogram that DC Line Fault has removed main website under operating mode；
Fig. 7 is the electrical quantity oscillogram that DC Line Fault has removed slave station under operating mode；
Fig. 8 is the electrical quantity oscillogram that DC Line Fault does not remove main website under operating mode；
Fig. 9 is the electrical quantity oscillogram that DC Line Fault does not remove slave station under operating mode.
Specific embodiment
Specific embodiment of the invention is further described below in conjunction with the accompanying drawings.
A kind of embodiment of MMC direct-current short circuits fault detection method of the present invention：
The both-end or multiterminal that the hybrid modularization multi-level converter of half-bridge as shown in Figure 1, full-bridge submodule is constituted are soft
Property DC transmission system, full-bridge and half-bridge submodule quantity are respectively N, M, wherein N >=2, M >=2 in system；In Fig. 1：usmIt is son
Module voltage, UdcIt is DC voltage, HBSM (half-bridge sub-module) is half-bridge submodule, FBSM (full-
Bridge sub-module) it is full-bridge submodule.After detecting DC bipolar short trouble and occurring, full-bridge submodule can be with
Output negative voltage, can make system on the premise of maintaining alternating voltage amplitude constant using this characteristic, more neatly control
System dc voltage U processeddc.The ability of negative level can be exported using full-bridge submodule, transverter is using not locking transverter
Mode carries out DC Line Fault and passes through, and fault current is restricted to 0, this process Neutron module voltage usmRated value is maintained always.
After DC current is restricted to 0, short trouble is to be eliminated, and the DC voltage of DC transmission system starts to recover
Flow, DC voltage starts to recover preceding, it is necessary to follow the steps below direct-current short circuit fault condition detection：
As shown in Fig. 2 maintain transverter and net state, from each current conversion station select one as main website, will normally transport
DC voltage station is determined as main website during row, and remaining is used as slave station；For main website, while itself submodule voltage is controlled,
Slope according to setting gradually lifts the first direct current biasing, and DC voltage is gradually lifted from zero；Slave station is controlling itself submodule
While block voltage, according to DC current value of feedback and the difference of DC current reference value, by proportional controller or proportional integral
Controller, generates the second direct current biasing of bridge arm modulation instructions, slave station is tracked the DC voltage of main website；Wherein, the first direct current
Biasing is respectively the bridge arm voltage for combining three-phase modulations ripple generation main website and slave station, bridge arm voltage meter with the second direct current biasing
Formula is as follows：
In formula, work as varmFor main website transverter bridge arm voltage when, Udc_ratedIt is the rated value of DC voltage, k is first straight
Flow the perunit value of biasing, eabcIt is three-phase modulations ripple；Work as varmFor slave station transverter bridge arm voltage when, Udc_ratedIt is DC voltage
Rated value, k is the perunit value of the second direct current biasing, eabcIt is three-phase modulations ripple.
During failure judgement, when the actual DC voltage of main website detection is less than continuing for the 90% of the first direct current biasing setting value
When time is more than setting time T1, judge that direct-current short circuit failure is still present, i.e., direct-current short circuit failure is not removed yet so far, is changed
Main website control model, it is zero DC voltage control to control main website, no longer lifts DC voltage；Above-mentioned setting time T1 is straight with first
The rate of rise and control parameter for flowing biasing are relevant；Set when the actual DC voltage of main website detection is consistently greater than the first direct current biasing
The 90% of definite value, or when being less than setting time T2 less than 90% duration of the first direct current biasing setting value, judge straight
Flow short-circuit failure has been removed, and continues to lift up the first direct current biasing of main website, and slave station continues to be tracked according to the second direct current biasing to be led
The DC voltage stood.Each current conversion station switches back into original normal operation shape after judging that DC voltage reaches rated value and stabilization
State, main website and slave station revert to the mode of operation before failure.
Main website uses Converter controller as described below with the control of slave station：
Controller inner ring is still using the electric current PI controllers under traditional dq rotating coordinate systems；D shaft currents command value by
Submodule voltage control outer shroud generation, by by submodule average voltage compared with command value send into PI controllers obtain；q
Shaft current command value is generated by Reactive Power Control outer shroud, and PI controls are sent into by the way that reactive power value of feedback is compared with command value
Device processed is obtained.The three-phase modulations ripple e that control inner ring is obtainedabc, it is necessary to obtain 6 outputs of bridge arm after being processed according to the following formula
Voltage：
In formula, varmIt is each bridge arm output voltage, Udc_ratedIt is the rated value of DC voltage, eabcIt is three-phase modulations
Ripple, k is the perunit value of the first direct current biasing or the second direct current biasing, k=1 during normal operation；System is in detection direct-current short circuit event
During whether barrier is removed, the computational methods of k values according to current conversion station can be main website or slave station and different, for main website, control k
Rated value is gradually risen up to from 0 according to setting slope, for slave station, k is by DC current negative-feedback through proportional controller or ratio
Example integral controller is obtained；The value of sign is relevant with the position of each bridge arm in formula, such as in Fig. 1, bridge arm is defeated in calculating
Above formula takes negative sign when going out voltage, and above formula takes positive sign when calculating the output voltage of lower bridge arm.
The direct current biasing of main website first is lifted in the case of in order to avoid not removed in direct-current short circuit failure causes direct current
Flow through big, produce dash current, the command value of the perunit value of the first direct current biasing of main website is divided into two parts, a part be according to
From 0 command value for gradually rising up to rated value, another part is the command value of DC current restriction controller output to setting slope,
Calculating formula is as follows：
k1=kref+kerr
In formula, k1For main website adds the first direct current biasing after Current limited Control, krefIt is gradually to be gone up from 0 according to setting slope
Rise to the command value of rated value, kerrIt is the command value of DC current restriction controller output.
The control principle of DC current restriction controller is as shown in figure 5, the controller is divided into cap controller and lower limit control
Device two parts processed.Cap controller includes：After DC current higher limit is compared with DC current sampled value, feeding PI controls
Device, the integrator in the PI controllers only works when output is more than -1 less than 0；Lower limit controller includes：By under DC current
After limit value compares with DC current sampled value, PI controllers are sent into, the integrator in the PI controllers is only less than in output more than 0
Worked when 1.Two output valves of PI controllers are added and obtain final output kerr。
The characteristics of above-mentioned DC current restriction controller is to be output as 0 when DC current is not up to the bound of setting,
Normal control is not influenceed, and is started working when DC current crosses upper and lower limit, the first direct current biasing in modifier controller,
DC current is limited in allowed band.It is secondary caused by lifting DC voltage during so as to avoiding direct-current short circuit failure from not removing
Main current conversion station DC voltage lifting is too fast after fault current, and direct-current short circuit fault clearance, and remaining current conversion station fails in time
Tracking, caused dash current.
During direct-current short circuit fault detect, as the control block diagram of the current conversion station of main website as shown in figure 3, in traditional electricity
On the basis of stream inner ring, using submodule voltage controller as watt current outer shroud, for stablizing transverter submodule voltage；
Meanwhile, using reactive power controller as reactive current outer shroud, make transverter to be company in whole failover procedure
The power network for connecing provides reactive power support.
As the control block diagram of the current conversion station of slave station as shown in figure 4, as main website, in the base of traditional current inner loop
On plinth, using submodule voltage controller as watt current outer shroud, for stablizing transverter submodule voltage；Using idle work(
Rate controller enables transverter power network to provide reactive power and supports as reactive current outer shroud.
In slave station when each bridge arm output voltage is calculated, the determination of direct current biasing perunit value is as shown in figure 4, pass through direct current
Stream feeds back to compare with DC current reference value and is calculated through proportional controller or pi controller afterwards, usual DC current
Reference value could be arranged to 0, and the selection of electric current positive direction is inflow transverter direction.Now, when the DC voltage of main website output is carried
When rising, can increase the sample DC current that obtains of slave station side, compare with reference value afterwards through pi controller (or ratio
Controller) amplify after, the direct current biasing of slave station is increased, the DC voltage of slave station side will rise therewith, and master is followed so as to reach
Stand the effect of DC voltage.
By taking both-end flexible direct current power transmission system as an example, emulated using MATLAB/SIMULINK short to MMC direct currents of the invention
Road fault detection method is verified.
The emulation operating mode removed of direct-current short circuit failure, now main website waveform is as shown in fig. 6, in 0.1s, select it is main,
From current conversion station, DC current restriction controller is added, start to lift the first direct current biasing according to setting slope, it is straight in lifting process
Stream voltage and the first direct current biasing keep highly consistent, therefore, it is determined that direct-current short circuit failure is fully erased, continuation is according to setting
Determine slope lifting direct current biasing, the steady lifting of DC voltage is shown as in waveform.Slave station waveform is as shown in fig. 7, its direct current
Pressure can preferably track main website from start to finish, during tracking, because detection time delay and the influence of controller characteristic can go out
The existing DC current of about 0.3pu, but due to the inhibitory action of DC current restriction controller, now DC current is limited in
0.2pu.Visible by Fig. 6, Fig. 7, whole process Neutron module voltage stabilization, reactive power output is normal, and electrical quantity is maintained
Stabilization, does not have curtage to impact.
Direct-current short circuit failure does not remove the main website waveform of operating mode, slave station waveform respectively as shown in Figure 8, Figure 9, equally in 0.1s
The master and slave current conversion stations of Shi Xuanding, add DC current restriction controller, proceed by the first direct current biasing in lifting controller,
But because direct-current short circuit failure is not recovered, lifting direct current biasing can cause DC current to exceed setting 0.2pu, therefore, direct current
Current limit controller is started working, and DC voltage is limited near 0pu all the time, after a period of time, system discovery direct current
Compacting measured value is not up to 90% of the first direct current biasing in controller all the time, therefore, it is determined that direct-current short circuit failure is not removed,
Maintenance DC voltage is 0 control model.
From Fig. 8, Fig. 9, the DC current for the passing through respectively less than 0.25pu of main website and slave station in whole process, to system
Safety is not impacted, while it is clear not yet accurately to determine direct-current short circuit failure on the premise of additional detection apparatus are not increased
Remove, illustrate the security and validity of the detection method.
In the present embodiment, both can be as main website using the current conversion station of constant DC voltage control during normal operation, it is also possible to
Used as slave station, other current conversion stations can also be used as main website, or slave station, that is to say, that for a current conversion station, existing as main
Stand and lift the ability of the first direct current biasing, also there is the ability that DC voltage is tracked as slave station；When normal operation using fixed straight
When flowing voltage-controlled current conversion station as slave station, by prescribed master in other current conversion stations.
The half-bridge plus full-bridge submodule that direct-current short circuit fault detection method of the invention is applicable not only to shown in Fig. 1 are hybrid
Multilevel converter, be equally applicable to full-bridge submodule multilevel converter.
The present invention is communicated between need not being stood in DC Line Fault detection process, it is not necessary to increase other testing equipments,
It is the detection for being capable of achieving short trouble only by original DC voltage, current sensor, is that direct-current short circuit failure is not fully erased
Lifting DC voltage is provided and ensured afterwards, is not resulted in second short circuit, submodule repid discharge and is bypassed and converter blocking jump
Lock problem.
A kind of embodiment of MMC direct-current short circuits failure detector of the present invention：
Including with lower unit：
Select unit：For selecting a current conversion station as main website, other current conversion stations are used as slave station；
Judging unit：DC voltage is started from scratch lifting, real-time detection direct current in lifting process for the main website
Pressure, the slave station is according to DC current value of feedback and the difference of DC current reference value, the DC voltage of synchronized tracking main website；Work as institute
When stating time of the DC voltage continuously less than the first setting value for T1, judge that direct-current short circuit failure is still present.
Signified MMC direct-current short circuit failure detectors, are actually based on the inventive method flow in above-described embodiment
A kind of computer solution, i.e., a kind of software architecture may apply in current conversion station, and said apparatus are and method flow
Corresponding treatment progress.Because the sufficiently clear of the introduction to the above method is complete, and the device reality that the present embodiment is claimed
It is a kind of software architecture on border, therefore is no longer described in detail.
Claims (10)
1. a kind of MMC direct-current short circuits fault detection method, it is characterised in that comprise the following steps：
, used as main website, other current conversion stations are used as slave station for one current conversion station of selection；DC voltage is started from scratch lifting by the main website,
Real-time detection DC voltage in lifting process, the slave station according to DC current value of feedback and the difference of DC current reference value, together
The DC voltage of step tracking main website；When the DC voltage is T1 continuously less than the time of the first setting value, judge that direct current is short
Road failure is still present.
2. MMC direct-current short circuits fault detection method according to claim 1, it is characterised in that when direct-current short circuit failure still
In the presence of so, it is zero DC voltage control state to control the main website.
3. MMC direct-current short circuits fault detection method according to claim 1, it is characterised in that when the direct current pressure holding
When the continuous time more than or equal to the first setting value is T2, judge that direct-current short circuit failure has been removed, main website continues to lift up direct current
Voltage, until being promoted to DC voltage rated value.
4. MMC direct-current short circuits fault detection method according to claim 1, it is characterised in that the main website is according to setting
The first direct current biasing, the DC voltage is started from scratch lifting, when DC voltage is T1 less than the time of the first setting value
When, judge that direct-current short circuit failure is still present；First direct current biasing is used to combine three-phase modulations ripple generation main website transverter
Bridge arm voltage.
5. MMC direct-current short circuits fault detection method according to claim 1, it is characterised in that the slave station is by direct current
After stream value of feedback makees difference with DC current reference value, by proportional controller or pi controller, generation bridge arm modulation refers to
Second direct current biasing of order；Second direct current biasing is used to combine the bridge arm voltage that three-phase modulations ripple generates slave station transverter.
6. MMC direct-current short circuit fault detection methods according to claim 4 or 5, it is characterised in that the main website transverter
Or the bridge arm voltage calculating formula of slave station transverter is as follows：
In formula, work as varmFor main website transverter bridge arm voltage when, Udc_ratedIt is the rated value of DC voltage, k is that the first direct current is inclined
Put, eabcIt is three-phase modulations ripple；Work as varmFor slave station transverter bridge arm voltage when, Udc_ratedIt is the rated value of DC voltage, k is
Second direct current biasing, eabcIt is three-phase modulations ripple.
7. MMC direct-current short circuits fault detection method according to claim 6, it is characterised in that when k is the first direct current biasing
When, k is by command value krefWith command value kerrAddition is obtained, krefBe gradually risen up to by 0 according to specified slope 1 command value,
kerrTo limit the command value of DC current.
8. MMC direct-current short circuits fault detection method according to claim 7, it is characterised in that the main website was being lifted
In journey DC voltage, when DC current is more than the upper limit of setting or the lower limit less than setting, first direct current biasing is corrected,
By DC current control between the upper limit and lower limit.
9. a kind of MMC direct-current short circuits failure detector, it is characterised in that including with lower unit：
Select unit：For selecting a current conversion station as main website, other current conversion stations are used as slave station；
Judging unit：DC voltage is started from scratch lifting, real-time detection DC voltage in lifting process, institute for the main website
Slave station is stated according to DC current value of feedback and the difference of DC current reference value, the DC voltage of synchronized tracking main website；When described straight
When stream voltage is T1 continuously less than the time of the first setting value, judge that direct-current short circuit failure is still present.
10. MMC direct-current short circuits failure detector according to claim 9, it is characterised in that also including for working as direct current
When short trouble is still present, the unit that the main website is zero DC voltage control state is controlled.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107748313A (en) * | 2017-10-16 | 2018-03-02 | 华北电力大学 | Based on or logic identification HBSM MMC internal short circuit faults method |
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| CN112684290B (en) * | 2020-12-16 | 2022-11-04 | 华北电力大学 | Efficient calculation method for interelectrode short-circuit fault current of flexible direct-current power grid |
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