CN108512201A - A kind of multiterminal flexible direct current power grid DC line fast protection method and system - Google Patents
A kind of multiterminal flexible direct current power grid DC line fast protection method and system Download PDFInfo
- Publication number
- CN108512201A CN108512201A CN201810457902.6A CN201810457902A CN108512201A CN 108512201 A CN108512201 A CN 108512201A CN 201810457902 A CN201810457902 A CN 201810457902A CN 108512201 A CN108512201 A CN 108512201A
- Authority
- CN
- China
- Prior art keywords
- current
- fpt
- fault
- voltage
- calculated
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 42
- 230000005540 biological transmission Effects 0.000 claims abstract description 36
- 230000005611 electricity Effects 0.000 claims abstract description 27
- 238000005070 sampling Methods 0.000 claims abstract description 14
- 230000001681 protective effect Effects 0.000 claims abstract description 11
- 239000000284 extract Substances 0.000 claims abstract description 9
- 230000009466 transformation Effects 0.000 claims description 6
- 238000004590 computer program Methods 0.000 claims description 5
- 230000004888 barrier function Effects 0.000 claims description 4
- 230000009471 action Effects 0.000 abstract description 3
- 238000004088 simulation Methods 0.000 description 22
- 230000008859 change Effects 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 9
- 238000004458 analytical method Methods 0.000 description 8
- 230000008901 benefit Effects 0.000 description 5
- 238000001514 detection method Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 230000001052 transient effect Effects 0.000 description 4
- 230000004069 differentiation Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000000977 initiatory effect Effects 0.000 description 3
- 238000002955 isolation Methods 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- 101100499229 Mus musculus Dhrsx gene Proteins 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- NAWXUBYGYWOOIX-SFHVURJKSA-N (2s)-2-[[4-[2-(2,4-diaminoquinazolin-6-yl)ethyl]benzoyl]amino]-4-methylidenepentanedioic acid Chemical compound C1=CC2=NC(N)=NC(N)=C2C=C1CCC1=CC=C(C(=O)N[C@@H](CC(=C)C(O)=O)C(O)=O)C=C1 NAWXUBYGYWOOIX-SFHVURJKSA-N 0.000 description 1
- 241000208340 Araliaceae Species 0.000 description 1
- 235000005035 Panax pseudoginseng ssp. pseudoginseng Nutrition 0.000 description 1
- 235000003140 Panax quinquefolius Nutrition 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 210000001367 artery Anatomy 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 235000008434 ginseng Nutrition 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000035772 mutation Effects 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 210000003462 vein Anatomy 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
Classifications
-
- 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
-
- G—PHYSICS
- G01—MEASURING; TESTING
- 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
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
-
- 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
- H02H7/28—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 meshed systems
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The invention discloses a kind of multiterminal flexible direct current power grid DC line fast protection method and systems, include the following steps：Acquire the voltage and current at the protection element being connected with DC power transmission line positive and negative electrode；Short trouble occurs for transmission line of electricity, and protective device starts, and extracts the voltage and current sample value of setting time after failure；FPT is calculated using the voltage sample value extracted after failure, the ratio of initial and most end positive current differential and cathodal current difference in sampled data window is calculated using the current sampling data extracted after failure；By the FPT being calculated compared with the FPT threshold values of setting, internal fault external fault is differentiated；By the positive current differential being calculated and the ratio of cathodal current difference compared with the threshold value of setting, Judging fault pole.The quick action of guard method of the present invention only utilizes the single ended voltage and electric current of protected circuit, can meet rapidity requirement of the multiterminal flexible direct current power grid to protection.
Description
Technical field
The present invention relates to electric system multiterminal flexible direct current power grid DC line fault discrimination technology fields, and in particular to one
Kind multiterminal flexible direct current power grid DC line fast protection method and system.
Background technology
Half-bridge module multilevel converter (HB-MMC) and traditional wire commutation transverter (LCC) and two power level voltage source types
Transverter (VSC) is compared, and is gradually applied in the flexible DC power transmission engineering of both ends because having significant advantage, and will
It is used widely in many multiterminal flexible direct current electricity power engineerings that will be built.Multiterminal flexible direct current power grid and both ends direct current
Transmission system, which is compared, has significant advantage, improves power supply reliability as transmission line of electricity possesses more redundancies, required current conversion station
Quantity reduces and reduces construction cost and the loss of whole power transmission etc..However, being limited on protection system used leaves much room
Development based on HB-MMC DC grids.
In multiterminal flexible direct current power grid, when short trouble occurs for DC side, and using AC circuit breaker or have
The current conversion station of failure current limit ability is compared, and fault section is isolated using the dc circuit breaker for being connected to transmission line of electricity both ends
The normal operation that can ensure non-faulting part is best protected mode.However, due to the low damping characteristic of straight-flow system,
When short trouble occurs for DC side, fault current rises rapidly and peak value is high, jeopardizes the same of current conversion station semiconductor devices safety
When, bring larger pressure to cut-offfing for dc circuit breaker.In view of the limitation of current failure current limit and dc circuit breaker technical merit,
It is necessary to study the quick protection philosophy based on single-end information.
The prior art proposes the protected mode based on current-limiting inductance both sides voltage change ratio and utilization current-limiting inductance direct current
The voltage change ratio in line side differentiates internal fault external fault.Protected mode based on voltage change ratio is not necessarily between transmission line of electricity both ends
Communication, and protect speed that can meet DC grid to protecting the requirement of quick-action to protect however, when fault resstance is larger
The sensitivity and reliability of shield can substantially reduce.
The prior art proposes that the Non-unit protection method based on incident traveling wave, the guard method have not by line boundary shadow
Loud advantage.The prior art also proposes the guard method based on current traveling wave Mintrop wave head.However, when transmission line length is shorter
When, the reliability of both the above guard method is relatively low, in addition, the reliability of traveling-wave protection by fault point transition resistance influenced compared with
It is serious.
Fault signature when short trouble occurs for straight-flow system of the prior art detailed analysis based on VSC, and then proposes
A kind of guard method differentiating internal fault external fault by fault location.However, the guard method by fault resstance influenced compared with
To be serious, in addition, the guard method does not account for requirement of the multiterminal flexible direct current power grid to protection quick-action.
By analyze above it is found that presently, there are identified based on voltage change ratio, traveling wave and parameter DC grid guarantor
Shield mode influenced by fault resstance it is more serious, and some protected modes cannot meet straight-flow system to protection speed want
It asks.In addition, majority protected mode can be only applied to symmetrical monopolar straight-flow system at present, and it is few suitable for symmetrical bipolar DC system
Protected mode.
Invention content
To solve the above-mentioned problems, the present invention analyzes DC line area in the symmetrical bipolar DC grid based on HB-MMC
Fault transient voltage when inside and outside failure, and a kind of multiterminal flexible direct current power grid AC line based on single-end information is proposed accordingly
Road fast protection method and system.In the analytic process of false voltage, transmission line of electricity uses distributed parameter model, and application is folded
Add principle and the analysis method of Laplace transformation；Define FPT be false voltage waveform catastrophe point between first extreme point when
Between be spaced, FPT when troubles inside the sample space is far smaller than FPT when external area error, can determine internal fault external fault accordingly；In addition,
It is proposed a kind of failure pole method of discrimination based on positive and negative anodes fault current.The guard method rapid sensitive, and do not need power transmission line
Data transmission between the both ends of road, is not influenced substantially by transition resistance.
To achieve the above object, concrete scheme of the invention is as follows：
The first object of the present invention be disclose a kind of multiterminal flexible direct current power grid DC line fast protection method, including
Following steps：
Acquire the voltage and current at the protection element being connected with DC power transmission line positive and negative electrode；
Short trouble occurs for transmission line of electricity, and protective device starts, and extracts the voltage and current sample of setting time after failure
Value；
FPT is calculated using the voltage sample value extracted after failure, sampling is calculated using the current sampling data extracted after failure
The ratio of initial and most end positive current differential and cathodal current difference in data window；
By the FPT being calculated compared with the FPT threshold values of setting, internal fault external fault is differentiated；
By the positive current differential being calculated and the ratio of cathodal current difference compared with the threshold value of setting, event is differentiated
Hinder pole.
Further, FPT is after short trouble occurs, and voltage waveform is from starting to be mutated to reaching for the first time between extreme point
Time interval.
Further, the FPT threshold values are during setting, false voltage when according to internal fault external fault, solve
Be out of order the analytical expression of voltage, carries out Laplace transformation to false voltage, then be superimposed with initial voltage, obtains former inside and outside area
FPT values when barrier, FPT values when according to obtained internal fault external fault, determine FPT threshold values.
Further, by the FPT being calculated compared with the FPT threshold values of setting, differentiate internal fault external fault, specially：
If the FPT being calculated is less than the FPT threshold values of setting, it is determined as troubles inside the sample space；Otherwise, it is determined that for outside area
Failure.
Further, by the threshold value ratio of the ratio and setting of the positive current differential being calculated and cathodal current difference
Compared with, Judging fault pole, specially：
If the ratio of the positive current differential and cathodal current difference that are calculated is more than the threshold value of setting, judge
For plus earth failure；
If the ratio of the positive current differential and cathodal current difference that are calculated is less than the inverse of the threshold value of setting,
Then it is determined as cathode earth fault；
If threshold value and setting of the ratio of the positive current differential and cathodal current difference that are calculated between setting
Threshold value inverse between, then be determined as bipolar short trouble.
Further, the threshold value of the setting is preferably 1.2.
The second object of the present invention be disclose a kind of multiterminal flexible direct current power grid DC line rapid protection system, including
Server, the server include memory, processor and storage on a memory and the computer that can run on a processor
Program, the processor realize following steps when executing described program：
Acquire the voltage and current at the protection element being connected with DC power transmission line positive and negative electrode；
Short trouble occurs for transmission line of electricity, and protective device starts, and extracts the voltage and current sample of setting time after failure
Value；
FPT is calculated using the voltage sample value extracted after failure, sampling is calculated using the current sampling data extracted after failure
The ratio of initial and most end positive current differential and cathodal current difference in data window；
By the FPT being calculated compared with the FPT threshold values of setting, internal fault external fault is differentiated；
By the positive current differential being calculated and the ratio of cathodal current difference compared with the threshold value of setting, event is differentiated
Hinder pole.
The third object of the present invention is to disclose a kind of computer readable storage medium, is stored thereon with computer program,
The program executes following steps when being executed by processor：
Acquire the voltage and current at the protection element being connected with DC power transmission line positive and negative electrode；
Short trouble occurs for transmission line of electricity, and protective device starts, and extracts the voltage and current sample of setting time after failure
Value；
FPT is calculated using the voltage sample value extracted after failure, sampling is calculated using the current sampling data extracted after failure
The ratio of initial and most end positive current differential and cathodal current difference in data window；
By the FPT being calculated compared with the FPT threshold values of setting, internal fault external fault is differentiated；
By the positive current differential being calculated and the ratio of cathodal current difference compared with the threshold value of setting, event is differentiated
Hinder pole.
Beneficial effects of the present invention：
(1) it based on the voltage theory analysis in the multiterminal flexible direct current power grid to HB-MMC when generation internal fault external fault, carries
Go out a kind of DC line protection method based on single-end information.The guard method is differentiated by means of the FPT of fault transient voltage
Internal fault external fault, while identifying failure pole using positive and negative electrode current.
(2) quick action of the guard method.The guard method only utilizes the single ended voltage and electric current of protected circuit,
Protection sampled data window width is 2ms, can meet rapidity requirement of the multiterminal flexible direct current power grid to protection.
(3) reliability of the guard method is high.When fault resstance is larger, which remains to correct decision and goes out event in area
Barrier, and the influence of unrestricted galvanic electricity sense value.
(4) setting valve protected is only related to current conversion station and line parameter circuit value, and therefore, the protected mode is not by institute's protection circuit
The influence of transimission power and input current conversion station number.
(5) the guard method principle is simple, is easy to Project Realization, has higher practical value.
Description of the drawings
Fig. 1 is the line chart of four end flexible direct current electricity power engineering of Zhangbei County；
Additional equivalent circuit when Fig. 2 (a) is troubles inside the sample space；
Additional equivalent circuit when Fig. 2 (b) is positive external area error；
Additional equivalent circuit when Fig. 2 (c) is back side external area error；
Fig. 3 (a) is F1Voltage when metallicity plus earth failure occurs for place parses waveform；
Fig. 3 (b) is F2Voltage when metallicity plus earth failure occurs for place parses waveform；
Fig. 3 (c) is F3Voltage when metallicity plus earth failure occurs for place parses waveform；
Fig. 4 is protection flow chart；
Fig. 5 (a) is F1Voltage simulation waveform when metallicity plus earth failure occurs for place；
Fig. 5 (b) is F2Voltage simulation waveform when metallicity plus earth failure occurs for place；
Fig. 5 (c) is F3Voltage simulation waveform when metallicity plus earth failure occurs for place；
Fig. 6 is F1Current simulations waveform when metallicity plus earth failure occurs for place；
Fig. 7 (a) is F1False voltage simulation waveform when bipolar short trouble occurs for place；
Fig. 7 (b) is F2False voltage simulation waveform when bipolar short trouble occurs for place；
Fig. 7 (c) is F3False voltage simulation waveform when bipolar short trouble occurs for place；
Fig. 8 is F1Fault current simulation waveform when bipolar short trouble occurs for place；
Fig. 9 is false voltage waveform when fault resstance takes different value.
Specific implementation mode：
The present invention is described in detail below in conjunction with the accompanying drawings：
It should be noted that term used herein above is merely to describe specific implementation mode, and be not intended to restricted root
According to the illustrative embodiments of the application.Additionally, it should be understood that when in the present specification use term "comprising" and/
Or when " comprising ", existing characteristics, step, operation, device, component and/or combination thereof are indicated.
In order to solve the problems in the existing technology, the present invention provides a kind of, and the multiterminal based on single-end information are flexible straight
Galvanic electricity net DC line protection method, includes the following steps：
(1) current conversion station is equivalent to the tandem compound of capacitance and inductance, transmission line of electricity uses distributed parameter model.Using folded
Add the false voltage of principle and the method for Laplace transformation to internal fault external fault when to carry out Analytical Solution, and then constructs internal fault external fault
Protection criteria sets the threshold value FPT of FPTth；FPT is after short trouble occurs, and voltage waveform is from mutation is started to reaching for the first time
Time interval between extreme point.
(2) positive and negative anodes current flow configuration failure pole identical criterion, setting failure pole is applied to differentiate threshold value kset；
(3) protective device acquires the voltage and current of protection installation place in real time, and DC line occurs short trouble and protects
After device starts, the voltage and current data of 2ms after failure are extracted；
(4) voltage sample value calculates FPT after utilizing failure, and △ I are calculated using fault current sampled valuep/△In；
(5) by FPT and FPTthAfter differentiate internal fault external fault, while according to the ratio of positive and negative anodes fault current variable quantity
Judging fault pole.When being determined as troubles inside the sample space, and selection is out of order after polar curve i.e. transmission trip signal, and then complete paired fault pole
The isolation of line.
In step (1), the setting up procedure of the internal fault external fault identical criterion based on fault transient voltage is：
The guard method is illustrated by taking four end flexible direct current electricity power engineering of Zhangbei County as an example, Fig. 1 show the engineering
Line chart, fault point F in figure1、F2And F3It is located in the positive electrode bus of 1 right endpoint of circuit, current conversion station 1 and 2；Rij(ij=
12,21,13,31,24,42,34,43) it is the protective device of circuit end points；Line length marks in figure.
With R12The guard method is introduced for the positive route protection at place, Fig. 2 (a), (b) and (c) are respectively area
Additional equivalent circuit interior, outside outside forward region and dorsal zone when metallicity plus earth failure, L in figureSAnd CSRespectively current conversion station
Equivalent inductance and equivalent capacity, can be acquired by formula (4), L in formulaAFor bridge arm inductance value, CSMFor submodule capacitance, N is
Submodule number contained by each bridge arm；P is complex operation symbol, LBThe galvanic electricity that is limited inductance value, u0The electricity at prior fault point occurs for failure
Pressure.As seen from the figure, the voltage and current amount of the transmission line of electricity both sides indicated with distributed parameter model when internal fault external fault is satisfied by
Relationship shown in formula (5).
In formula (5), l is the length of transmission line of electricity, γ and ZcExpression formula respectively as shown in formula (6), (7), wherein R0、L0、
G0And C0The respectively resistance of unit length transmission line of electricity, inductance, conductance and capacitance.
F1When metallicity plus earth failure occurs for place, it can be obtained by formula (5) and the relationship of line boundary voltage and electric current attached
Add U in equivalent circuit1Expression formula such as formula (8) shown in, L in formulaTFor LSWith LBThe sum of.
F2When metallicity plus earth failure occurs for place, it can be obtained by formula (5) and the relationship of line boundary voltage and electric current attached
Add U in equivalent circuit1Expression formula such as formula (9) shown in, in formula, Z1And Z2Expression formula respectively as shown in formula (10), (11).
Z2=p2CS(LB+LT)+1(11)
F3When metallicity plus earth failure occurs for place, it can be obtained by formula (5) and the relationship of line boundary voltage and electric current attached
Add U in equivalent circuit1Expression formula such as formula (12) shown in, in formula, Z3And Z4Expression formula respectively as shown in formula (13), (14).
Z3=p3LBLTCS+pCSZc 2+pLB (13)
Z4=p2CSZc(LT+LB)+Zc (14)
Formula (8), (9) and (12) is subjected to Laplace inverse transformation respectively, F can be obtained after being added with initial voltage respectively1、F2With
F3R when metallicity plus earth failure occurs for place12The voltage expression at place, voltage parse waveform respectively as Fig. 3 (a), (b) and
(c) shown in, accordingly, FPT values as shown in Table 1 when internal fault external fault can be obtained, and then threshold value FPT can be setth, herein
By FPTthIt is set as 0.3ms.For bipolar short trouble, false voltage analytic process and analytic process when monopolar grounding fault
It has no big different.
FPT values when 1 internal fault external fault of table
In step (2), failure pole differentiates threshold value ksetSetting up procedure it is as follows：
When monopolar grounding fault occurs, when the impedance value of fault loop is much smaller than normal operation, therefore, even if between having circuit
Coupling, the variable quantity of failure electrode current is far longer than the current change quantity of non-faulting pole.And bipolar short trouble occurs
When, positive and negative polarities current change quantity is almost the same.Therefore, it can differentiate anode by comparing the curent change in positive and negative anodes circuit
Earth fault, cathode earth fault and bipolar short trouble.In order to simplify differentiation process, using in sampled data window initially and most
The current data at end, the variable quantity △ I of positive and negative electrode current are acquired by formula (15)pWith △ In.Ideally, bipolar short trouble
When △ Ip/△InIt is 1,1 is more than when positive short trouble, and be less than 1 when cathode short trouble, in order to ensure reliability, by kset
It is set as 1.2.
In step (5), fault distinguishing detailed process is as shown in figure 4, now do as described below：
For symmetrical bipolar DC grid, protection system includes mainly three parts：Protection startup, fault identification and failure pole
Selection.The purpose that protection starts is starting protection algorithm, and fault identification part is used for differentiating internal fault external fault, the selection of failure pole
Purpose is Judging fault pole.In view of high-voltage direct current power grid to protecting the high requirement of system quick-action that can reduce the reliable of protection
Property, in order to distinguish failure and interference, it is also necessary to independently of the fault detection part except fault identification and the selection of failure pole.Mesh
Before, protection starts more mature because of the extensive use in the HVDC power transmission engineerings based on LCC with fault detection technique.Cause
This, briefly introduces protection actuating section herein, and mainly introduces fault identification and selected with failure pole.
In order to ensure that protection algorism can start rapidly when any failure occurs for system, protection actuating section should have
Standby higher sensitivity.Start-up criterion can utilize voltage change ratio du/dt or current changing rate di/dt, in view of current limliting electricity
Sense is more serious to the weakening effect of fault current change rate, using du/dt as fault initiating criterion, to improve the quick-action of protection
Property.
Protection flow chart is as shown in figure 4, figure includes protection startup, fault detect, internal fault external fault identification and failure pole
Selection.In order to improve the quick-action of protection, after fault initiating, internal fault external fault identification and fault detect start simultaneously at work.
In Fig. 4, module 1 and module 2 are internal fault external fault identification module and failure pole selecting module respectively.Internal fault external fault identification division
Once determining FPT<FPTth, at the same time failure pole selected section differentiation is out of order pole, it is necessary to be sent to trip signal
Corresponding dc circuit breaker, to complete Fault Isolation.
In module 1, the sampled data window length after fault initiating is selected as 2ms.By the analysis of step (1) it is found that reason
In the case of thinking, R12The positive voltage-to-ground at place is identical when plus earth failure is with bipolar short trouble.Therefore, this guard method
Voltage across poles sampled value is not needed, the protection for positive circuit, either plus earth failure or bipolar short trouble, only
Need the sampled value of positive voltage-to-ground that can differentiate internal fault external fault.It is symmetrical bipolar DC system, the protection system of cathode in view of system
System is nearly identical with anode.Fault detection part breaks down in confirmation rather than after interfering, and module 2 starts immediately, opens
Begin to calculate △ Ip/△In, by a series of comparisons, can determine failure pole.
In conclusion DC grid occur short trouble and after it protects system to start, fault identification module basis immediately
False voltage sampled value differentiates internal fault external fault；Simultaneous faults detection part discriminates whether faulty generation, when being determined as failure
Start the differentiation to failure pole；Finally, it after being determined as troubles inside the sample space and identification is out of order extremely, is sent to corresponding breaker
Trip signal completes Fault Isolation.
Flexible direct current power system simulation model is built using PSCAD, simulating, verifying is carried out to institute's extracting method：
1) model is established
To verify the validity of put forward protected mode herein, according to the topological structure and ginseng of four end flexible direct current power grid of Zhangbei County
Number, has built simulation model in PSCAD/EMTDC.In the model, Zhangbei County station, Fengning station and Kangbao County station are all made of and determine wattful power
Rate controls, and Beijing Station uses constant DC voltage control；Modulation system approaches modulation using nearest level, the modulation system and arteries and veins
Rushing width modulated and comparing has the advantages that modulating frequency is low, switching loss is low.Four current conversion stations pass through the transformer of exchange side
It is connected to 500kV AC systems.DC line uses the aerial line model based on frequency, in length and Fig. 1 labelled in reality
Border line length is identical.
2) monopolar grounding fault emulates
In view of the symmetry of system, have come guard method when verifying monopolar grounding fault by taking plus earth failure as an example
Effect property.In Fig. 1, in F1、F2And F3Plus earth failure is respectively set in place, and the failure generation moment is set as 1.5s, R12The failure at place
For voltage waveform respectively shown in such as Fig. 5 (a), (b) and (c), the simulation result of FPT is as shown in table 2.By Fig. 3 (a), (b) and (c) and
Fig. 5 (a), (b) and (c), Tables 1 and 2 compare as it can be seen that analysis result can be consistent with simulation result well.It can by table 2
See, FPT when troubles inside the sample space is less than threshold value, and FPT when external area error is much larger than threshold value, therefore the protection can be correct
Differentiate internal fault external fault.
Simulation result when 2 plus earth failure of table
F1The simulation waveform that fault current when plus earth failure occurs for place is as shown in Figure 6.As seen from the figure, positive electrode current
Variation is far longer than cathodal current.In table 2, △ Ip/△InValue prove, in no forum or area outside short trouble occurs, the event
Barrier pole method of discrimination can correctly differentiate pole of being out of order.
3) bipolar short-circuit simulation
Respectively in F1、F2And F3Bipolar short trouble, R is arranged in place12The false voltage and current waveform at place are respectively such as Fig. 7
(a), shown in (b), (c) and Fig. 8, table 3 show the simulation result of anode protection.Fig. 7 (a), (b) and (c) show that generation is bipolar
When short trouble, positive voltage-to-ground waveform and cathode voltage-to-ground waveform are symmetrical.It is compared it can be found that F with Fig. 51Place
When metallicity plus earth failure and bipolar short trouble occurs, R12The positive voltage-to-ground waveform at place is almost the same.Fig. 8 tables
Bright, when bipolar short trouble occurs, positive and negative electrode current is also symmetrical.By table 3 as it can be seen that carried criterion can correctly identify area
Inside and outside failure, simultaneous faults pole criterion can accurate Judging fault poles.
Simulation result when 3 bipolar short trouble of table
4) influence of fault resstance
By the above simulating, verifying as it can be seen that when metallic short circuit failure occurs, carried protection can differentiate fast and reliablely
It has internal fault external fault and failure pole.And fault resstance can influence the reliability based on traveling-wave protection, in order to verify proposed protection
Anti- resistance ability carries out following emulation.
Assuming that plus earth failure occurs for the intermediate of transmission line of electricity 1, fault resstance is respectively 0,50 Ω and 500 Ω.Fig. 9 institutes
It is shown as R12The false voltage waveform at place.By simulation waveform as it can be seen that with fault resstance increase, the first extreme value of false voltage waveform
The amplitude of point is gradually reduced, but FPT values remain unchanged.Therefore, which is not influenced substantially by fault resstance, this is to be carried
Main advantage of the protection philosophy compared with the protection philosophy based on false voltage change rate.
5) influence of current-limiting inductance value
In order to test the protection whether the influence of restricted flow inductance value, LBValue 0.1H is reduced to by 0.2H, and system
Other parameters remain unchanged, F1、F2And F3When plus earth failure occurs for place, simulation result is as shown in table 4.
4 L of tableBValue becomes the plus earth fault simulation result of 0.1H
By the above simulation result as it can be seen that when current-limiting inductance value is changed to 0.1H, which still can be with correct decision area
Inside and outside failure, while can be with correct decision failure pole.It is worth noting that, the value of current-limiting inductance should reasonably select, protecting
While card can be with correct decision internal fault external fault, it is ensured that can limit fault current in several milliseconds after failure generation
Within the rupturing capacity of dc circuit breaker.
The present invention utilizes the distributed parameter model of transmission line of electricity, by principle of stacking and Laplace transformation to fault transient voltage
Analytical analysis is carried out, to set internal fault external fault identical criterion according to analysis result, while utilizing the variation of positive and negative electrode current
Measure Judging fault pole.Simulation analysis shows that under various fault conditions, the present invention can correctly identify internal fault external fault and event
Hinder pole, high sensitivity is highly reliable.In addition, the present invention only needs the data window of 2ms to calculate, quick action.
The present invention further discloses a kind of multiterminal flexible direct current power grid DC line rapid protection systems, including service
Device, the server include memory, processor and storage on a memory and the computer program that can run on a processor,
The processor realizes following steps when executing described program：
Acquire the voltage and current at the protection element being connected with DC power transmission line positive and negative electrode；
Short trouble occurs for transmission line of electricity, and protective device starts, and extracts the voltage and current sample of setting time after failure
Value；
FPT is calculated using the voltage sample value extracted after failure, sampling is calculated using the current sampling data extracted after failure
The ratio of initial and most end positive current differential and cathodal current difference in data window；
By the FPT being calculated compared with the FPT threshold values of setting, internal fault external fault is differentiated；
By the positive current differential being calculated and the ratio of cathodal current difference compared with the threshold value of setting, event is differentiated
Hinder pole.
The present invention further discloses a kind of computer readable storage mediums, are stored thereon with computer program, the program
Following steps are executed when being executed by processor：
Acquire the voltage and current at the protection element being connected with DC power transmission line positive and negative electrode；
Short trouble occurs for transmission line of electricity, and protective device starts, and extracts the voltage and current sample of setting time after failure
Value；
FPT is calculated using the voltage sample value extracted after failure, sampling is calculated using the current sampling data extracted after failure
The ratio of initial and most end positive current differential and cathodal current difference in data window；
By the FPT being calculated compared with the FPT threshold values of setting, internal fault external fault is differentiated；
By the positive current differential being calculated and the ratio of cathodal current difference compared with the threshold value of setting, event is differentiated
Hinder pole.
Above-mentioned, although the foregoing specific embodiments of the present invention is described with reference to the accompanying drawings, not protects model to the present invention
The limitation enclosed, those skilled in the art should understand that, based on the technical solutions of the present invention, those skilled in the art are not
Need to make the creative labor the various modifications or changes that can be made still within protection scope of the present invention.
Claims (8)
1. a kind of multiterminal flexible direct current power grid DC line fast protection method, which is characterized in that include the following steps：
Acquire the voltage and current at the protection element being connected with DC power transmission line positive and negative electrode；
Short trouble occurs for transmission line of electricity, and protective device starts, and extracts the voltage and current sample value of setting time after failure；
FPT is calculated using the voltage sample value extracted after failure, sampled data is calculated using the current sampling data extracted after failure
The ratio of initial and most end positive current differential and cathodal current difference in window；
By the FPT being calculated compared with the FPT threshold values of setting, judge to differentiate internal fault external fault；
By the positive current differential being calculated and the ratio of cathodal current difference compared with the threshold value of setting, Judging fault
Pole.
2. a kind of multiterminal flexible direct current power grid DC line fast protection method described in claim 1, which is characterized in that FPT
After short trouble occurs, voltage waveform is from starting to be mutated to the time interval reached for the first time between extreme point.
3. a kind of multiterminal flexible direct current power grid DC line fast protection method described in claim 1, which is characterized in that described
FPT threshold values during setting, false voltage when according to internal fault external fault solves the Analytical Expression of false voltage
Formula carries out Laplace transformation to false voltage, is then superimposed with initial voltage, obtains FPT values when internal fault external fault, according to obtaining
Internal fault external fault when FPT values, determine FPT threshold values.
4. a kind of multiterminal flexible direct current power grid DC line fast protection method described in claim 1, which is characterized in that will count
Obtained FPT differentiates internal fault external fault, specially compared with the FPT threshold values of setting：
If the FPT being calculated is less than the FPT threshold values of setting, it is determined as troubles inside the sample space；Otherwise, it is determined that for event outside area
Barrier.
5. a kind of multiterminal flexible direct current power grid DC line fast protection method described in claim 1, which is characterized in that will count
The ratio of obtained positive current differential and cathodal current difference is compared with the threshold value of setting, Judging fault pole, specially：
If the ratio of the positive current differential and cathodal current difference that are calculated is more than the threshold value of setting, it is determined as just
Pole ground fault；
If the ratio of the positive current differential and cathodal current difference that are calculated is less than the inverse of the threshold value of setting, sentence
It is set to cathode earth fault；
If the ratio of the positive current differential and cathodal current difference that are calculated is between the threshold value of setting and the door of setting
Between the inverse of threshold value, then it is determined as bipolar short trouble.
6. a kind of multiterminal flexible direct current power grid DC line fast protection method described in claim 5, which is characterized in that described
The threshold value of setting is preferably 1.2.
7. a kind of multiterminal flexible direct current power grid DC line rapid protection system, which is characterized in that including server, the service
Device include memory, processor and storage on a memory and the computer program that can run on a processor, the processor
Following steps are realized when executing described program：
Acquire the voltage and current at the protection element being connected with DC power transmission line positive and negative electrode；
Short trouble occurs for transmission line of electricity, and protective device starts, and extracts the voltage and current sample value of setting time after failure；
FPT is calculated using the voltage sample value extracted after failure, sampled data is calculated using the current sampling data extracted after failure
The ratio of initial and most end positive current differential and cathodal current difference in window；
By the FPT being calculated compared with the FPT threshold values of setting, internal fault external fault is differentiated；
By the positive current differential being calculated and the ratio of cathodal current difference compared with the threshold value of setting, Judging fault
Pole.
8. a kind of computer readable storage medium, is stored thereon with computer program, which is characterized in that the program is held by processor
Following steps are executed when row：
Acquire the voltage and current at the protection element being connected with DC power transmission line positive and negative electrode；
Short trouble occurs for transmission line of electricity, and protective device starts, and extracts the voltage and current sample value of setting time after failure；
FPT is calculated using the voltage sample value extracted after failure, sampled data is calculated using the current sampling data extracted after failure
The ratio of initial and most end positive current differential and cathodal current difference in window；
By the FPT being calculated compared with the FPT threshold values of setting, internal fault external fault is differentiated；
By the positive current differential being calculated and the ratio of cathodal current difference compared with the threshold value of setting, Judging fault
Pole.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810457902.6A CN108512201B (en) | 2018-05-14 | 2018-05-14 | A kind of multiterminal flexible direct current power grid DC line fast protection method and system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810457902.6A CN108512201B (en) | 2018-05-14 | 2018-05-14 | A kind of multiterminal flexible direct current power grid DC line fast protection method and system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108512201A true CN108512201A (en) | 2018-09-07 |
| CN108512201B CN108512201B (en) | 2019-06-21 |
Family
ID=63400527
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810457902.6A Expired - Fee Related CN108512201B (en) | 2018-05-14 | 2018-05-14 | A kind of multiterminal flexible direct current power grid DC line fast protection method and system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108512201B (en) |
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109119977A (en) * | 2018-09-20 | 2019-01-01 | 山东大学 | Multiterminal flexible direct current power grid DC line fast protection method and system based on single ended voltage |
| CN111313440A (en) * | 2020-02-11 | 2020-06-19 | 南方电网科学研究院有限责任公司 | Method and device for protecting unbalanced grounding electrode line of multi-terminal direct current transmission system |
| CN111579929A (en) * | 2020-05-25 | 2020-08-25 | 国网上海市电力公司 | Direct-current power distribution network fault current-limiting protection method based on multi-terminal data |
| CN111614065A (en) * | 2020-05-07 | 2020-09-01 | 国网四川省电力公司 | Line disconnection protection method based on line parameter identification |
| CN112444667A (en) * | 2019-09-02 | 2021-03-05 | 南京理工大学 | Boundary protection method for direct-current power distribution network |
| CN112904142A (en) * | 2021-01-19 | 2021-06-04 | 国网江苏省电力有限公司徐州供电分公司 | Single-pole ground fault protection method for direct-current power distribution network grounded through clamping resistor |
| CN113013854A (en) * | 2021-03-11 | 2021-06-22 | 中国大唐集团科学技术研究院有限公司华中电力试验研究院 | Method for prejudging faults inside and outside area based on differential current change rate in dynamic process |
| CN113030653A (en) * | 2021-05-06 | 2021-06-25 | 重庆大学 | Fault identification method for single-end protection of direct-current power grid |
| CN113092950A (en) * | 2021-05-17 | 2021-07-09 | 重庆大学 | Fault identification method for double-end protection of direct-current power grid |
| CN113300343A (en) * | 2021-06-24 | 2021-08-24 | 国网山东省电力公司电力科学研究院 | Flexible direct current power grid fault line identification method based on cosine similarity |
| CN113376549A (en) * | 2021-05-26 | 2021-09-10 | 国网上海能源互联网研究院有限公司 | Pilot protection method and system for flexible direct current power distribution network |
| CN113471940A (en) * | 2021-07-02 | 2021-10-01 | 天津大学 | MMC-HVDC protection method based on voltage high-low frequency ratio difference |
| CN113644635A (en) * | 2021-07-13 | 2021-11-12 | 西安理工大学 | Method for judging internal and external faults of direct current line area of flexible direct current transmission system |
| CN113740664A (en) * | 2021-08-23 | 2021-12-03 | 中国南方电网有限责任公司超高压输电公司广州局 | Direct current system fault positioning method and device, computer equipment and storage medium |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102820643A (en) * | 2012-08-20 | 2012-12-12 | 山东大学 | High voltage direct current power transmission line protection method based on voltage and current mutation direction |
| CN103633629A (en) * | 2013-11-11 | 2014-03-12 | 同济大学 | High-voltage direct current power transmission line protection method based on wavelet transformation and energy spectrum analysis |
| CN105098738A (en) * | 2015-09-08 | 2015-11-25 | 山东大学 | Pilot protection method of high-voltage direct current transmission line based on S transformation |
| CN106058828A (en) * | 2016-07-18 | 2016-10-26 | 天津大学 | Multi-terminal flexible DC power grid line direction pilot protection method |
| CN107979075A (en) * | 2017-11-27 | 2018-05-01 | 山东大学 | A kind of multiterminal flexible direct current power grid DC line Non-unit protection method |
-
2018
- 2018-05-14 CN CN201810457902.6A patent/CN108512201B/en not_active Expired - Fee Related
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102820643A (en) * | 2012-08-20 | 2012-12-12 | 山东大学 | High voltage direct current power transmission line protection method based on voltage and current mutation direction |
| CN103633629A (en) * | 2013-11-11 | 2014-03-12 | 同济大学 | High-voltage direct current power transmission line protection method based on wavelet transformation and energy spectrum analysis |
| CN105098738A (en) * | 2015-09-08 | 2015-11-25 | 山东大学 | Pilot protection method of high-voltage direct current transmission line based on S transformation |
| CN106058828A (en) * | 2016-07-18 | 2016-10-26 | 天津大学 | Multi-terminal flexible DC power grid line direction pilot protection method |
| CN107979075A (en) * | 2017-11-27 | 2018-05-01 | 山东大学 | A kind of multiterminal flexible direct current power grid DC line Non-unit protection method |
Cited By (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109119977A (en) * | 2018-09-20 | 2019-01-01 | 山东大学 | Multiterminal flexible direct current power grid DC line fast protection method and system based on single ended voltage |
| CN109119977B (en) * | 2018-09-20 | 2019-07-23 | 山东大学 | Multiterminal flexible direct current power grid DC line fast protection method and system based on single ended voltage |
| CN112444667A (en) * | 2019-09-02 | 2021-03-05 | 南京理工大学 | Boundary protection method for direct-current power distribution network |
| CN112444667B (en) * | 2019-09-02 | 2024-02-13 | 南京理工大学 | Boundary protection method for direct-current power distribution network |
| CN111313440A (en) * | 2020-02-11 | 2020-06-19 | 南方电网科学研究院有限责任公司 | Method and device for protecting unbalanced grounding electrode line of multi-terminal direct current transmission system |
| CN111313440B (en) * | 2020-02-11 | 2021-11-26 | 南方电网科学研究院有限责任公司 | Method and device for protecting unbalanced grounding electrode line of multi-terminal direct current transmission system |
| CN111614065A (en) * | 2020-05-07 | 2020-09-01 | 国网四川省电力公司 | Line disconnection protection method based on line parameter identification |
| CN111579929A (en) * | 2020-05-25 | 2020-08-25 | 国网上海市电力公司 | Direct-current power distribution network fault current-limiting protection method based on multi-terminal data |
| CN112904142A (en) * | 2021-01-19 | 2021-06-04 | 国网江苏省电力有限公司徐州供电分公司 | Single-pole ground fault protection method for direct-current power distribution network grounded through clamping resistor |
| CN113013854A (en) * | 2021-03-11 | 2021-06-22 | 中国大唐集团科学技术研究院有限公司华中电力试验研究院 | Method for prejudging faults inside and outside area based on differential current change rate in dynamic process |
| CN113013854B (en) * | 2021-03-11 | 2023-06-16 | 中国大唐集团科学技术研究院有限公司华中电力试验研究院 | Method for pre-judging faults inside and outside area based on differential current change rate in dynamic process |
| CN113030653A (en) * | 2021-05-06 | 2021-06-25 | 重庆大学 | Fault identification method for single-end protection of direct-current power grid |
| CN113092950A (en) * | 2021-05-17 | 2021-07-09 | 重庆大学 | Fault identification method for double-end protection of direct-current power grid |
| CN113376549A (en) * | 2021-05-26 | 2021-09-10 | 国网上海能源互联网研究院有限公司 | Pilot protection method and system for flexible direct current power distribution network |
| CN113376549B (en) * | 2021-05-26 | 2024-04-19 | 国网上海能源互联网研究院有限公司 | Pilot protection method and pilot protection system for flexible direct-current power distribution network |
| CN113300343A (en) * | 2021-06-24 | 2021-08-24 | 国网山东省电力公司电力科学研究院 | Flexible direct current power grid fault line identification method based on cosine similarity |
| CN113300343B (en) * | 2021-06-24 | 2022-08-26 | 国网山东省电力公司电力科学研究院 | Flexible direct-current power grid fault line identification method based on cosine similarity |
| CN113471940B (en) * | 2021-07-02 | 2022-07-19 | 天津大学 | MMC-HVDC protection method based on voltage high-low frequency ratio difference |
| CN113471940A (en) * | 2021-07-02 | 2021-10-01 | 天津大学 | MMC-HVDC protection method based on voltage high-low frequency ratio difference |
| CN113644635A (en) * | 2021-07-13 | 2021-11-12 | 西安理工大学 | Method for judging internal and external faults of direct current line area of flexible direct current transmission system |
| CN113740664A (en) * | 2021-08-23 | 2021-12-03 | 中国南方电网有限责任公司超高压输电公司广州局 | Direct current system fault positioning method and device, computer equipment and storage medium |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108512201B (en) | 2019-06-21 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108512201B (en) | A kind of multiterminal flexible direct current power grid DC line fast protection method and system | |
| CN109217267B (en) | Multiterminal flexible direct current power grid longitudinal protection method and system based on current-limiting inductance polarity of voltage | |
| CN107104416B (en) | The DC line relay protecting method of direct-flow distribution system is pressed during a kind of multiterminal are flexible | |
| CN108663602B (en) | Flexible direct current power distribution network monopole failure line selection and Section Location and system | |
| CN105548819B (en) | A kind of HVDC transmission line internal fault external fault recognition methods based on anti-traveling wave | |
| CN108054736B (en) | A kind of multiterminal flexible direct current power grid DC line protection method based on voltage pole wave | |
| CN105098738B (en) | A kind of HVDC transmission line longitudinal protection method based on S-transformation | |
| US11190010B2 (en) | Annular bearer network and service bearing implementation method therefor | |
| CN108832605B (en) | The longitudinal protection method of identification mixing both-end DC power transmission line area internal and external fault | |
| CN106468752B (en) | The solid circuit breaker RCD buffer circuit and Fault Locating Method of integrated fault location | |
| CN105518958B (en) | DC power network currents differential protecting method and its system | |
| CN104377667A (en) | High-voltage direct-current line pilot protection method based on boundary energy | |
| CN109975657A (en) | Single-phase ground fault line selecting method of small-electric current grounding system based on differential characteristic value | |
| CN102969888A (en) | Design method for multi media card (MMC) self-defining submodule based on real time digital system (RTDS) | |
| US11677231B2 (en) | Single-phase reclosing method, device and storage medium for AC/DC system | |
| CN108196162A (en) | The DC distribution net monopolar grounding fault wireline inspection method of model and parameters identification | |
| CN101915888A (en) | Extensible fusion identification method for lightening interference of +/-800kV direct current transmission line | |
| CN104538941A (en) | Traveling wave protection fixed value setting method for high-voltage direct-current transmission line | |
| CN109884453A (en) | A kind of DC filter high-voltage capacitor fault recognition method based on parameter identification | |
| CN110350493A (en) | Middle pressure flexible direct current system fault detection method based on line current second dervative | |
| Yang et al. | Multi-Frequency bands based Pole-to-Ground fault detection method for MMC-Based radial DC distribution systems | |
| CN110441659A (en) | A kind of fault distinguishing method of HVDC transmission line | |
| CN108808634A (en) | HVDC transmission line longitudinal protection method based on smoothing reactor voltage | |
| CN109193595B (en) | Active power distribution network failure separation method based on current phase comparison | |
| CN111130072A (en) | Novel active protection device in direct current system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20190621 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |