CN110474306A - A kind of guard method and system of the dead-zone fault in DC grid - Google Patents
A kind of guard method and system of the dead-zone fault in DC grid Download PDFInfo
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- CN110474306A CN110474306A CN201910781820.1A CN201910781820A CN110474306A CN 110474306 A CN110474306 A CN 110474306A CN 201910781820 A CN201910781820 A CN 201910781820A CN 110474306 A CN110474306 A CN 110474306A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
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Abstract
The guard method and system of the present invention relates to a kind of in DC grid dead-zone fault, method includes when the local main protection in DC grid determines that confusion region failure occurs for route, then the electric current in local dc circuit breaker being made to be transferred to transfer branch by main branch；Time difference criterion and zero crossing criterion are constructed based on line line wave；Time difference criterion and zero crossing criterion are subjected to logic or operation, the specific location that confusion region failure occurs is judged according to the result of logic or operation；If confusion region failure occurs to issue to local dc circuit breaker in area when distal end and jump order；If failure generation in confusion region when proximal end, makes the electric current in local dc circuit breaker be transferred to main branch by transfer branch outside area.The mentioned criterion setting of the present invention is simple, does not depend on communication, and method in the present invention, which need to only be added, for the route to have put into operation can be further improved protective value, without changing former main protection setting, has stronger application value.
Description
Technical field
The present invention relates to the fault distinguishing fields of the transmission line of electricity of flexible HVDC transmission system, and in particular to one kind is in direct current
The guard method of dead-zone fault in power grid.
Background technique
The advantage that direct current transportation and multi-terminal system are had both based on the multiterminal element power grid of flexible direct current technology, complied with " with
Clean energy resource is to dominate, interconnect extensively by bulk transmission grid, each continent in various countries of extra-high voltage grid " Times ' Demand, be solve great Rong
Amount power transmission, extensive new energy concentration are sent outside and the important channel of big system interconnection problem.However, at present towards multiterminal element electricity
The protection philosophy of net is still immature: on the one hand, it is contemplated that when failure occurs in DC grid, the electric current rate of climb is very fast, protection
It is required that completing the detection of failure, typical time period 3ms in Millisecond time scale；On the other hand, existing to flexible direct current system
The route protection principle of system remains some problems to be solved in terms of balance reliability, sensitivity and quick-action index.
At this stage, the protection philosophy of flexible direct current route is divided into two classes: Non-unit protection principle, both-end amount protection philosophy.
The protection of both-end amount can cover total track length, but in view of message capacity, the false difference stream of external area error and optical-fibre channel propagation are prolonged
When the problems such as, if logicalnot circuit is very short, generally only use as back-up protection.There are experts and scholars to attempt to utilize Bei Ruilong at present
Model profile parameter model compensating electric capacity electric current solves the problems, such as the long delay that the adjoint capacitor charge and discharge of wave process expedites the emergence of out.
But consider integrity problem, current engineering protection philosophy all tends to construct site protection philosophy using one-terminal data.
Non-unit protection principle, that is, site protection philosophy, only relying on one-terminal data and can completing is to the fault distinguishing of transmission line of electricity
The technology of one great prospect.The main protections machines such as traveling-wave protection, differential under-voltage protection based on current conventional high-pressure direct current transportation
Reason, has derived a series of boundary protections.
Such as: it is temporary to fault current high frequency by wavelet transformation using reactor boundary to the retardation of high fdrequency component
The diversity judgement of state energy goes out outside area, troubles inside the sample space, and then distinguishes fault zone by the polarity of voltage at reactor both ends；For
Both ends are equipped with the route of inductance, propose the Protection criteria of the difference based on additional inductor Initial Voltage Value in area, outside area, make
Protection seting is obtained not depend on emulation and have higher reliability；For the line line wave and zero line occurred simultaneously in ground fault
The difference of velocity of wave propagation proposes the guard method for shrinking boundary actively according to the difference of traveling wave arrival time.It is above-mentioned
Research has greatly pushed the development of DC grid technology, but still there are two problems for boundary protection: 1) in different failures
When position, anti-transition resistance ability is different.2) it is the selectivity for guaranteeing protection, can sacrifices to a certain range of protection energy of route
Power.
Converter station outlet is installed in for direct current reactor, between route " mesh-structured " engineering without obvious boundary and
Speech, protection internal fault external fault high fdrequency component otherness will substantially reduce, to guarantee external area error reliably not malfunction, it is necessary to substantially mention
Height adjusts threshold, and the recognition capability of high resistive fault is in sacrificial region to ensure selectivity.
Summary of the invention
The guard method of technical problem to be solved by the invention is to provide a kind of in DC grid dead-zone fault, can
The route for not depending on communication completes differentiation to far-end fault in area and external area error, can be with by the cooperation with Main Protection
Complete the quick identification protecting to whole line fault.
The technical scheme to solve the above technical problems is that a kind of protection side of the dead-zone fault in DC grid
Method includes the following steps,
When the local main protection in DC grid determines that confusion region failure occurs for route, then local dc circuit breaker is controlled
Movement makes the electric current in the local dc circuit breaker be transferred to transfer branch by main branch；
The line line wave in route is obtained, based on line line wave building time difference criterion and zero crossing criterion；
The time difference criterion and the zero crossing criterion are subjected to logic or operation, sentenced according to logic or the result of operation
The specific location that the confusion region failure of breaking occurs；
If the confusion region failure occurs in area when distal end, is issued to the local dc circuit breaker and jump order, make institute
Local dc circuit breaker is stated to disconnect；If the confusion region failure occurs when proximal end, to control the local direct current interruption outside area
Device movement makes the electric current in the local dc circuit breaker be transferred to main branch by transfer branch.
The beneficial effects of the present invention are: method of the invention propose based on line mould wavefront reaching time-difference twice come
It distinguishes the criterion of abort situation and abort situation is judged based on the line line wave zero crossing number after mathematical morphology analysis
Criterion, two criterions may determine that the specific location for generation of being out of order by logic or operation, can make if being judged as troubles inside the sample space
Breaker Accelerated trip is obtained, to realize the quick excision of failure；The mentioned method of the present invention is simple, reliable, and logic and principle are all
It is relatively simple, reliability and sensitivity of the invention can be stepped up by improving sample frequency, so that dead zone length is into one
Step shortens, and it is low or even tripping occurs ask can to make up anti-transition resistance ability of the technology today in area under far-end fault operating condition
Topic；And the mentioned criterion setting of the present invention is simple, does not depend on communication, method in the present invention need to only be added for the route to have put into operation
It can be further improved protective value, without changing former main protection setting, there is stronger application value.
Based on the above technical solution, the present invention can also be improved as follows.
Further, based on the line line wave building time difference criterion the specific steps are when the local in DC grid
When main protection determines that confusion region failure occurs for route, the line line wave that local measurement obtains is obtained, to measure obtained institute
Stating the primary line mould wavefront arrival time in line line wave is zero moment, records the line line wave in setting time window
Waveform, the secondary line mould wavefront arrival time in the line line wave is searched in the time window, and record calculating
Time difference between the primary line mould wavefront arrival time and the secondary line mould wavefront arrival time, obtain institute
State time difference criterion.
Further, judge that the concrete model of the distal end in area occurs for the confusion region failure according to the time difference criterion
For,
Wherein,
TbFor the inherent delay of the opposite opposite side dc circuit breaker of local dc circuit breaker, t0It is opposite with local main protection
Opposite side protection protection act delay, KrelIt is safety factor, xmaxFor the fault bit at local main protection maximum protection range
The percentage that the length apart from distal end accounts for total line length is set, l is total line length, v1Indicate the velocity of wave of line line wave；Δtset
The time difference threshold value adjusted to distinguish abort situation, Δ t are the primary line mould wavefront arrival time and described two
Time difference between secondary line mould wavefront arrival time.
Further, based on the line line wave building zero crossing criterion the specific steps are, to the line line wave carry out
It is analyzed with polar mathematical morphology, counts the zero crossing number of the line line wave after analyzing, obtain zero crossing criterion.
Further, judge that the concrete model of the distal end in area occurs for the confusion region failure according to the zero crossing criterion
For,
N > nset,
Wherein, n indicates the zero crossing number of the line line wave after analyzing, nsetIndicate adjusting zero crossing number.
Further, the specific location that the confusion region failure generation is judged according to the result of logic or operation, specifically includes,
When between the primary line mould wavefront arrival time and the secondary line mould wavefront arrival time
Between difference be greater than the time difference threshold under external area error operating condition, and be less than the time in area under maximum protection range position fault condition
Difference then determines that the distal end in area occurs for the confusion region failure, or, when the zero crossing number of the line line wave after analyzing
When greater than adjusting zero crossing number, then determine that the distal end in area occurs for the confusion region failure；
Otherwise, it is determined that the proximal end outside area occurs for the confusion region failure.
Further, the zero number that the adjusting zero crossing number theoretically can at least be captured by the time window
To adjust；
Further, the adjusting zero crossing number is equal to the zero point that theoretically can at least capture by the time window
Number adds default nargin zero crossing number.
Based on a kind of above-mentioned guard method of the dead-zone fault in DC grid, the present invention also provides one kind in DC grid
The protection system of middle dead-zone fault.
A kind of protection system of the dead-zone fault in DC grid, comprises the following modules,
Dc circuit breaker control module is used to determine that confusion region event occurs for route when the local main protection in DC grid
When barrier, then local dc circuit breaker movement is controlled, the electric current in the local dc circuit breaker is made to be transferred to transfer by main branch
Branch；
Criterion generation module is used to obtain the line line wave in route, is sentenced based on the line line wave building time difference
According to zero crossing criterion；
Abort situation judgment module is used to the time difference criterion and the zero crossing criterion carrying out logic or fortune
It calculates, the specific location that the confusion region failure occurs is judged according to the result of logic or operation；
The dc circuit breaker control module occurs if being also used to the confusion region failure in area when distal end, to institute
It states local dc circuit breaker and issues jump order, disconnect the local dc circuit breaker；If the confusion region failure occurs outside area
When proximal end, then the local dc circuit breaker movement is controlled, turns the electric current in the local dc circuit breaker by transfer branch
Move on to main branch.
The beneficial effects of the present invention are: system of the invention propose based on line mould wavefront reaching time-difference twice come
It distinguishes the criterion of abort situation and abort situation is judged based on the line line wave zero crossing number after mathematical morphology analysis
Criterion, two criterions may determine that the specific location for generation of being out of order by logic or operation, can make if being judged as troubles inside the sample space
Breaker Accelerated trip is obtained, to realize the quick excision of failure；The mentioned method of the present invention is simple, reliable, and logic and principle are all
It is relatively simple, reliability and sensitivity of the invention can be stepped up by improving sample frequency, so that dead zone length is into one
Step shortens, and it is low or even tripping occurs ask can to make up anti-transition resistance ability of the technology today in area under far-end fault operating condition
Topic；And the mentioned criterion setting of the present invention is simple, does not depend on communication, method in the present invention need to only be added for the route to have put into operation
It can be further improved protective value, without changing former main protection setting, there is stronger application value.
Based on a kind of above-mentioned guard method of the dead-zone fault in DC grid, the present invention also provides a kind of storages of computer
Medium.
It is as described above to be performed realization in described instruction for a kind of computer storage medium, including at least one instruction
Method and step.
Detailed description of the invention
Fig. 1 is that four end flexible HVDC transmission systems and abort situation illustrate schematic diagram；
Fig. 2 is the equivalent model of overhead transmission line；
Fig. 3 is to simplify line, zero mould equivalent network；
Fig. 4 is the flow chart of four end flexible direct current routes accelerated motion Non-unit protection scheme；
Fig. 5 is the F in Fig. 14Locate metallicity failure Kangbao County station side line mode voltage waveform；
Fig. 6 is the F in Fig. 13Locate metallicity failure Kangbao County station side line mode voltage waveform after morphological analysis；
Fig. 7 is the F in Fig. 11Locate metallicity failure Kangbao County station side line mode voltage waveform；
Fig. 8 is the F in Fig. 11Locate metallicity failure Kangbao County station side line mode voltage waveform after morphological analysis；
Fig. 9 is the F in Fig. 12Locate metallicity failure Kangbao County station side line mode voltage waveform；
Figure 10 is the F in Fig. 12Locate metallicity failure Kangbao County station side line mode voltage waveform after morphological analysis；
Figure 11 is the F in Fig. 13Locate metallicity failure Kangbao County station side line mode voltage waveform；
Figure 12 is the F in Fig. 13Locate metallicity failure Kangbao County station side line mode voltage waveform after morphological analysis；
Figure 13 is the F in Fig. 11Locate 300 ohm of transition resistance failure Kangbao County station side line mode voltage waveform；
Figure 14 is the F in Fig. 11Locate 300 ohm of transition resistance failure Kangbao County station side line mode voltage wave after morphological analysis
Shape；
Figure 15 is the relationship of dead zone length and sample frequency；
Figure 16 is protection scope between protection subregion and each criterion；
Figure 17 is a kind of flow chart of the guard method of the dead-zone fault in DC grid of the present invention.
Specific embodiment
The principle and features of the present invention will be described below with reference to the accompanying drawings, and the given examples are served only to explain the present invention, and
It is non-to be used to limit the scope of the invention.
It is specifically described the present invention below with reference to existing local main protection, existing local main protection is combined into the present invention
Time difference criterion and zero crossing criterion realize in DC grid dead zone thus ground connection barrier guard method process such as Fig. 4 institute
Show:
Firstly, introducing existing local Main Protection.The local Main Protection basic ideas applied in the application are as follows: benefit
With the speed difference of line line wave and zero line wave in route communication process, the line line experienced at local main protection is derived
The reaching time-difference of wave and zero line wave, to realize the protection to transmission line of electricity.But to guarantee selectivity in external area error
Malfunction will not occur under operating condition, confusion region (in confusion region=area proximal end outside distal end+area) can be set in route, will lead in this way
There are dead zones under far-end fault operating condition in area.
Main protection detailed process is as follows S1~S4:
S1 extracts pole tension and electrode current that local measurement obtains, by pole tension in the route where local main protection
It is converted with electrode current by triumphant human relations Bell, synthetic thread line wave and zero line wave.
In the S1, to capture the traveling wave in route, need to decouple pole tension and electrode current, synthetic thread line wave and
Zero line wave, the triumphant human relations Bell transformation utilized are shown below:
In formula, Up、UnRespectively indicate positive and negative electrode line voltage distribution, U1、U0Line, zero line wavelength-division after respectively indicating decoupling
Amount；
Calculate line, the method such as following formula of zero line wave is expressed:
Sk=(Uk-Zk·ik)/2 (2)
SkIndicate k line wave, UkIndicate k mode voltage, ikIndicate k mould electric current, ZkIndicate k mould wave impedance.
Abort situation and dc circuit breaker are disconnected (when local main protection judges that confusion region failure occurs in route, opposite side
Protection, which can issue trip signal, disconnects opposite side dc circuit breaker) position is set as traveling wave source, line can be derived by by Fig. 2
Mould-line mould folding, reflection coefficient α11、β11；Refraction coefficient α between-zero mould of line mould10 just、α10 is anti-, expression formula is as follows:
Z in formula1For route line line wave impedance, Z0For zero line wave impedance of route, RgFor the transition resistance of grounding point.
By the principle of duality, the reflection coefficient β of available-zero mould of zero mould00, the reflection coefficient α of-zero mould of zero mould00, zero
Mould-line mould refraction coefficient α01 just、α01 is anti-It is shown below:
Above-mentioned formula is compared with the catadioptric process that detailed analysis traveling wave is propagated in DC line, the source of line line wave
Can be made of several lower parts: 1) refraction of line line wave generates；2) zero line wave refraction generates；3) wave reflection of line line produces
It is raw.Due to zero line wave impedance Z of route0, usually line line wave impedance Z13-5 times, and the dispersion phenomenon of zero line wave
Obviously, influence of the zero line wave to line line wave can be ignored, using line line wave as research object.
S2 constructs Sudden Changing Rate direction start-up criterion using the anti-traveling wave energy of preceding traveling wave, it is prominent to judge whether fault traveling wave meets
The entry condition of variable directional element enters S3 if meeting, otherwise returns to S1.
In the S2, directional element is used to determine the direction that failure occurs, due to its higher reliability and sensitivity
Foundation as the starting of subsequent criterion.The direction start-up criterion of construction is shown below:
In formula, K1_set、K0_setFor line, the adjusting threshold of zero line wave, E1b、E1f、E0b、E0fRespectively line, the mutation of zero mould
The anti-traveling wave of amount, move ahead wave energy.By taking zero line wave as an example, calculation are as follows:
In formula, Δ u0、Δi0It is the variable quantity of zero mode voltage, electric current before time window τ compared with respective counts strong point, Z generation
The wave impedance of table route, when system operates normally, the numerical value of two parameter is all zero.
S3, call wire mould wavefront and zero mould wavefront arrival time calculate line mould wavefront and zero line wave
The time difference that wave head reaches；
S4 judges that position occurs for failure according to the time difference that line mould wavefront and zero mould wavefront reach, judges mould
Type is shown below:
First determine whether failure is non-external area error, if it is not, S1 is then returned to, if so, rapidly by local direct current interruption
The electric current of device is transferred to transfer branch by main branch；It then proceedes to judge whether failure is troubles inside the sample space, if so, issuing rapidly
Trip signal disconnects local dc circuit breaker, if it is not, then judging failure for confusion region failure.
When local main protection judges that confusion region failure occurs for route, the primary line mould as caused by failure can be generated on route
Traveling wave.Since failure is close away from opposite side protection at this time, opposite side protection can quickly and accurately identify failure；When failure is located in area
When, opposite side protection, which can issue trip signal, disconnects opposite side dc circuit breaker, and opposite side dc circuit breaker disconnects the secondary line generated
Line wave process local main protection can be experienced, and oscillation wave process can be generated；When failure is located at outside area, opposite side protection judgement
For external area error, secondary line line wave process would not be generated, is also just generated without oscillation traveling wave.Secondary line line wave process
Production principle is briefly to be located locally the confusion region of protection due to failure but protect in close situation away from opposite side, remote in area
It is generated under the failure of end by opposite side protection control opposite side dc circuit breaker disconnection.
The fault condition of distal end is compared with the secondary line mould that under external area error operating condition, the disconnection of opposite side dc circuit breaker is generated in area
Wavefront is different from the time difference of primary line mould wavefront that failure generates；Meanwhile line line wave passes through band polarity mathematics
It also will appear marked difference in zero crossing number after morphological analysis.As a result, when the local main protection in DC grid is sentenced
When confusion region failure occurs for alignment road, then enter method and step of the invention:
As shown in figure 17, a kind of guard method of the dead-zone fault in DC grid, includes the following steps, works as DC grid
In local main protection when determining that confusion region failure occurs for route, then control the movement of local dc circuit breaker, keep the local straight
Electric current in stream breaker, which is transferred to transfer branch by main branch, (in this step, makes the electric current in local dc circuit breaker by leading
Branch is transferred to transfer branch and can just be performed when judging failure for non-external area error, in the general introduction of above-mentioned Main Protection
It is described)；
The line line wave in route is obtained, based on line line wave building time difference criterion and zero crossing criterion；
The time difference criterion and the zero crossing criterion are subjected to logic or operation, sentenced according to logic or the result of operation
The specific location that the confusion region failure of breaking occurs；
If the confusion region failure occurs in area when distal end, is issued to the local dc circuit breaker and jump order, make institute
Local dc circuit breaker is stated to disconnect；If the confusion region failure occurs when proximal end, to control the local direct current interruption outside area
Device movement makes the electric current in the local dc circuit breaker be transferred to main branch by transfer branch.
In the present invention, when local main protection is judged as confusion region failure, local dc circuit breaker will carry out electric current
Pre- transfer because when local main protection is judged as confusion region failure, can not far-end fault and external area error in cog region, starting
Before mutually fast protection criterion (time difference criterion and zero crossing criterion) of the present invention, to guarantee quick-action, need that first local direct current breaks
The electric current of road device is transferred to transfer branch by main branch.
Under troubles inside the sample space operating condition and external area error operating condition, line mould wavefront reaching time-difference is had differences twice, tool
Body shows themselves in that
In area under far-end fault operating condition, line mould wavefront reaching time-difference twice are as follows:
TbIndicate the inherent delay of opposite side dc circuit breaker movement, t0Indicating opposite side guard time window length, (also referred to as opposite side is protected
The protection act of shield is delayed), the total line length of route where l indicates local main protection, x indicates that abort situation is protected apart from opposite side
Shield accounts for the percentage of total line length, v1Indicate the velocity of wave of line line wave.
Under external area error operating condition, time difference of line mould wavefront twice are as follows:
Δtout=tout2-tout1=Tb+t0；
TbIndicate the inherent delay of opposite side dc circuit breaker movement, t0Indicate opposite side guard time window length.
Thus, it is possible to the time difference of line mould wavefront is not fixed value twice when finding out troubles inside the sample space, but and failure
Position is related；When external area error, the wave head time difference of line line wave is fixed value twice.It therefore can be based on line line wave twice
The reaching time-difference of wave head constructs time difference criterion, specifically, obtaining primary line mould wavefront arrival time and secondary line mould
Wavefront arrival time calculated between primary line mould wavefront arrival time and secondary line mould wavefront arrival time
Time difference obtains time difference criterion.
Under troubles inside the sample space operating condition and external area error operating condition, line line wave by with polar mathematical morphology analysis after,
Significant difference, specific manifestation can be generated in zero crossing number are as follows:
In area under far-end fault operating condition, opposite side dc circuit breaker disconnect the secondary line line wave that generates can in abort situation and
Continuous oscillation occurs between the dc circuit breaker of opposite side, can be experienced at locally protection through abort situation；In external area error
Under operating condition, although above-mentioned oscillatory process can equally occur, since opposite side dc circuit breaker is already off, local protection is just
It can not experience.Therefore, the line line wave zero crossing number after being analyzed based on mathematical morphology constructs zero crossing criterion, tool
Body is analyze with polar mathematical morphology to the line line wave, counts the zero crossing of the line line wave after analyzing
Number, obtains zero crossing criterion.
Band polarity mathematics morphological analysis method, joined on the basis of traditional mathematics are morphologic for polarity of traveling wave
Recognition methods, specifically expressed by following formula:
With polar determination method are as follows:
If formula (12), (13) are not satisfied, MMF (Output) Morphological Gradient value is zero.δ value is smaller in formula, is used to
The phase that each point and original signal point occur in detection expansion and corrosion signal is advanced or retardation change.Change smaller in waveform or goes out
When existing noise, filter action can also be played.MMF(dil)Indicate expansion algorithm, MMF(ero)Indicate erosion algorithm, concrete operation method
It is then as follows:
Expansion and erosion operation are respectively indicated with ⊙, they are expressed as follows:
The continually changing oscillatory extinction wave of polarity can be carried out using the improvement mathematical Morphology Algorithm of above-mentioned introduction good
Good identification.
In this embodiment: the moment is occurred using failure and is delayed backward as zero moment for a period of time, and as benchmark,
Line line wave in one period of extension record backward forward, is sentenced based on line line wave structure time difference criterion and zero crossing
According to.
With failure occur the moment be starting zero moment, then be delayed backward at the time of are as follows:
At the time of tracing back to forward are as follows:
According to line mould wavefront reaching time-difference build time difference criterion twice, specifically:
Record primary line mould wavefront arrival time is t1, secondary line mould wavefront arrival time is t2, calculate twice
The line mould wavefront time difference are as follows: Δ t=t2-t1。
Settling time difference criterion, can be expressed by following formula:
Wherein,
TbFor the inherent delay of the opposite side dc circuit breaker opposite with local dc circuit breaker；t0For with local main protection phase
Pair opposite side protection act delay；KrelIt is safety factor, to avoid to the failure outside lateral areas close to outlet port, therefore KrelIt takes
0.1；xmaxFor the length of the abort situation distance distal end (i.e. opposite side protection) at local main protection maximum protection range, the line is busy that road is total
The percentage of length；L is total line length；v1Indicate the velocity of wave of line line wave；ΔtsetFor distinguish abort situation and adjust when
Between poor threshold value；Δ t be the primary line mould wavefront arrival time and the secondary line mould wavefront arrival time it
Between time difference.
The time of secondary line mould wavefront caused by the primary line mould wavefront caused by failure and breaker actuation
Poor Δ t is greater than the time difference threshold Δ t under external area error operating conditionset, and be less than in area under maximum protection range position fault condition
Time difference, then be determined as troubles inside the sample space.
Line line wave is analyzed according to band polarity configuration immunologing mathematics method, passes through waveform pass zero point after statistical analysis
Count the position to judge failure generation.Zero crossing identical criterion is established, specifically:
N > nset,
In formula, n indicates the zero crossing number of the line line wave after analyzing, nsetIndicate adjusting zero crossing number.Adjust zero passage
The number of point is adjusted by the zero number that time window theoretical minimum can capture, and considers certain nargin on this basis.
Time window length is 1.5 times of full swing period, two zero crossings of generation in a cycle of oscillation, under such troubles inside the sample space,
Theoretically time window can at least capture 3 zero crossings；But retain certain nargin (being preset as 2), the present invention selects 5 zero crossings
As adjusting number.
When the zero crossing number of the line line wave after analyzing is greater than adjusting zero crossing number, zero crossing criterion is judged as area
Internal fault.
The judging result of zero crossing criterion and time difference criterion is subjected to logic or judging result can be obtained in operation.
The mentioned criterion of the present invention protects the gamut of transmission line of electricity in combination with more good realize of current Main Protection
Shield.Criterion proposed by the present invention not serves as main protection, but utilizes one-terminal data main protection sensitivity when failure is close to protection
High feature.When failure is located at distal end in area, opposite side protection can be acted rapidly, according to the traveling wave after the movement of opposite side breaker
Feature, the mentioned criterion of the present invention identifies and judges the feature, thus precision maneuver.Meanwhile time difference criterion and zero passage
There is mutually matched relationships between point two criterions of criterion.
The model that four end flexible direct current system of Zhangbei County is built below with PSCAD/EMTDC, to method validation in the present invention:
1) according to the model of the soft lineal system in four end of Zhangbei County, four end direct current system models as shown in Figure 1, every line have been built
Road is all installed with smoothing reactor, size 0.05H, and the sample frequency of protective device is 200kHz, makes somebody a mere figurehead line model such as
((a) is transmission line spatial parameter in Fig. 2, is (b) soil parameters and transmission line position distribution) shown in Fig. 2；Simplify line, zero mould etc.
Imitating network, (1. ray indicates 2. line-line reflection wave, ray indicate 3. line-line refracted wave, ray indicate-zero folding of line as shown in Figure 3
4. ejected wave (anti-), ray indicate-zero refracted wave of line (just))；Dc circuit breaker delay T is setbAnd main protection delay t0For 2.0ms
And 0.5ms, dead zone proximal border (shown in Figure 16) account for the 15% of whole route.In Figure 16, A indicates the non-dead zone model of local main protection
It encloses, B indicates that local protection's dead-zone, C indicate the range that time difference criterion can be protected, and D indicates the model that zero crossing criterion can be protected
It encloses, E is indicated outside area.
By taking Kangbao County-Fengning route as an example, protection seting is carried out, process is as follows:
It (1) is 2.95*108m/s by the velocity of wave of route parameter calculation line line wave.
(2) by the abort situation of local main protection maximum protection range apart from distal end xmaxIt is for 15% and route overall length
184.4km can calculate the full swing period at local main protection: T=4*xmax*l/v1=4*15%*184.4km/ (295km/
Ms)=0.375ms
(3) it obtains obtaining t by substituting into dataDelay、tRetrospectCalculating process is as follows:
tDelay=Tb+t0+2xmaxl/v1=2.0+0.5+2*15%*184.4/295=2.6875ms,
tRetrospect=Tb+t0-0.2xmaxl/v1=2.0+0.5-0.2*15%*184.4/295=2.4813ms,
(4) adjusting of time difference criterion is carried out:
(5) zero crossing criterion time window, which takes, can capture 3 zero crossings, and a cyclically-varying can generate two zero passages
Point, time window window available in this way are long are as follows:
(6) theoretically, in area under far-end fault operating condition, 3 zero crossings can be at least captured in time window, to guarantee
Reliability of Microprocessor, the adjusting of zero crossing number are 5, are listed in following formula:
nset=5
Setting valve at similar available All other routes protective position, is listed in the table below:
Setting valve at each protective position of table 1
2) fault setting and introduction inside and outside Typical Areas
A, positive external area error F4, fault type is bipolar metallic earthing failure, the line mould that local main protection is experienced
Traveling-wave waveform and waveform after analyzing are as shown in Figure 5, Figure 6, and for convenience of describing and drawing, fault moment is denoted as starting zero
Moment, behind repeat no more.
B, distal end different location metallicity failure F in area1、F2、F3, waveform recording is in Fig. 7~12.
C, high resistive fault in area, specially F1Place is 300 ohm of ground faults, and waveform recording is in Figure 13 and Figure 14.
3) different faults scene simulation is verified
A, positive external area error F4If failure betides in Fig. 1, this landlord is protected under positive metallicity fault condition outside area
The time difference for the line wave of line twice experienced is protected after MATLAB draws, is differed using analyzing and calculating two wave crests
501 sampled points are 2.5ms according to the sample frequency 200kHz time difference of emulation, are met to the external area error operating condition time difference
The derivation of equation.Time difference criterion and zero crossing criterion will not all act.
B, distal end different location metallicity failure F in area1、F2、F3, failure, which is separately positioned on, protects 5km, 10km away from opposite side
At 27.6km (15%), protection act result is listed in table 2:
Different location fault protection situation in 2nd area of table
By 2 simulation result of table it is found that method proposed by the present invention can be identified correctly under the fault condition studied
Movement.
C, high resistive fault in area, in F1Place is respectively provided with 100,200,300 ohm of transition resistance failure, the present embodiment
Only in the traveling-wave waveform for depicting 300 ohm of transition resistances in Figure 13, Tu14Zhong, the simulation result by table 3 is available, in height
It can also correctly be identified under resistance failure.Protection act result is listed in table 3:
With the protection act result of different transition resistances in 3rd area of table
By sampling thheorem, the relationship between sampling thheorem and dead zone length and sample frequency can be drawn:
It is as shown in figure 15 to draw Dependence Results.Available by waveform in figure, under 200kHz frequency, dead zone length is accounted for
The 0.4% of whole route can reduce dead zone length by increasing sample frequency.Meanwhile 300 ohm of the most evil in distal end in area
It, still can be with precision maneuver under bad fault condition.
The present invention proposes distal end ground fault in a kind of area using the traveling wave feature of far-end fault in DC line area
Accelerate motion Non-unit protection method, according to the wave head time feature and morphological feature of line line wave, through simple mathematical morphology
The position that line fault occurs is judged after analysis.Due to can be under the premise of not changing main protection, and current Main Protection knot
It closes and improves its action performance, therefore, applicability with higher.
Based on a kind of above-mentioned guard method of the dead-zone fault in DC grid, the present invention also provides one kind in DC grid
The protection system of middle dead-zone fault.
A kind of protection system of the dead-zone fault in DC grid, comprises the following modules,
Dc circuit breaker control module is used to determine that confusion region event occurs for route when the local main protection in DC grid
When barrier, then local dc circuit breaker movement is controlled, the electric current in the local dc circuit breaker is made to be transferred to transfer by main branch
Branch；
Criterion generation module is used to obtain the line line wave in route, is sentenced based on the line line wave building time difference
According to zero crossing criterion；
Abort situation judgment module is used to the time difference criterion and the zero crossing criterion carrying out logic or fortune
It calculates, the specific location that the confusion region failure occurs is judged according to the result of logic or operation；
The dc circuit breaker control module occurs if being also used to the confusion region failure in area when distal end, to institute
It states local dc circuit breaker and issues jump order, disconnect the local dc circuit breaker；If the confusion region failure occurs outside area
When proximal end, then the local dc circuit breaker movement is controlled, turns the electric current in the local dc circuit breaker by transfer branch
Move on to main branch.
System of the invention proposes based on line mould wavefront reaching time-difference twice the criterion for distinguishing abort situation
Judge that the criterion of abort situation, two criterions pass through logic with the line line wave zero crossing number after analyzing based on mathematical morphology
Or operation may determine that the specific location for generation of being out of order, and breaker Accelerated trip can be made if being judged as troubles inside the sample space, from
And realize the quick excision of failure；The mentioned method of the present invention is simple, reliable, and logic and principle are all relatively simple, is adopted by improving
Sample frequency can step up reliability and sensitivity of the invention, so that dead zone length further shortens, can make up now
The problem of anti-transition resistance ability of the technology in area under far-end fault operating condition is low or even tripping occurs；And the mentioned criterion of the present invention
Adjusting is simple, does not depend on communication, method in the present invention, which need to only be added, for the route to have put into operation can be further improved protection
Performance has stronger application value without changing former main protection setting.
Based on a kind of above-mentioned guard method of the dead-zone fault in DC grid, the present invention also provides a kind of storages of computer
Medium.
It is as described above to be performed realization in described instruction for a kind of computer storage medium, including at least one instruction
Method and step.
The foregoing is merely presently preferred embodiments of the present invention, is not intended to limit the invention, it is all in spirit of the invention and
Within principle, any modification, equivalent replacement, improvement and so on be should all be included in the protection scope of the present invention.
Claims (10)
1. a kind of guard method of the dead-zone fault in DC grid, is characterized in that: including the following steps,
When the local main protection in DC grid determines that confusion region failure occurs for route, then it is dynamic to control local dc circuit breaker
Make, the electric current in the local dc circuit breaker is made to be transferred to transfer branch by main branch；
The line line wave in route is obtained, based on line line wave building time difference criterion and zero crossing criterion；
The time difference criterion and the zero crossing criterion are subjected to logic or operation, institute is judged according to the result of logic or operation
State the specific location of confusion region failure generation；
If the confusion region failure occurs in area when distal end, is issued to the local dc circuit breaker and jump order, make described
Ground dc circuit breaker disconnects；If the confusion region failure occurs that when proximal end, it is dynamic to control the local dc circuit breaker outside area
Make, the electric current in the local dc circuit breaker is made to be transferred to main branch by transfer branch.
2. a kind of dead zone in DC grid according to claim 1 thus ground connection barrier guard method, be characterized in that: being based on
Line line wave building time difference criterion the specific steps are when the local main protection in DC grid determines that mould occurs for route
When pasting area's failure, the line line wave that local measurement obtains is obtained, to measure the primary line in the obtained line line wave
Mould wavefront arrival time is zero moment, the waveform of the line line wave in setting time window is recorded, in the time window
Secondary line mould wavefront arrival time in the interior search line line wave, and record and calculate the primary line mould wavefront
Time difference between arrival time and the secondary line mould wavefront arrival time, obtain the time difference criterion.
3. a kind of guard method of dead-zone fault in DC grid according to claim 2, is characterized in that: according to described
Time difference criterion judges that the confusion region failure occurs the concrete model of distal end in area and is,
Wherein,
TbFor the inherent delay of the opposite side dc circuit breaker opposite with local dc circuit breaker, t0It is opposite with local main protection
The action delay of opposite side protection, KrelIt is safety factor, xmaxFor the abort situation distance at local main protection maximum protection range
The length of distal end accounts for the percentage of total line length, and l is total line length, v1Indicate the velocity of wave of line line wave；ΔtsetTo distinguish
Abort situation and the time difference threshold value adjusted, Δ t are the primary line mould wavefront arrival time and the secondary line mould
Time difference between wavefront arrival time.
4. a kind of dead zone in DC grid according to claim 2 or 3 thus ground connection barrier guard method, be characterized in that:
Based on line line wave building zero crossing criterion the specific steps are the line line wave obtained to local measurement carries out band
Polar mathematical morphology analysis, counts the zero crossing number of the line line wave after analyzing, obtains zero crossing criterion.
5. a kind of guard method of dead-zone fault in DC grid according to claim 4, is characterized in that: according to described
Zero crossing criterion judges that the confusion region failure occurs the concrete model of distal end in area and is,
N > nset,
Wherein, n indicates the zero crossing number of the line line wave after analyzing, nsetIndicate adjusting zero crossing number.
6. a kind of guard method of dead-zone fault in DC grid according to claim 4, is characterized in that: according to logic
Or the result of operation judges the specific location that the confusion region failure occurs, and specifically includes,
Time difference between the primary line mould wavefront arrival time and the secondary line mould wavefront arrival time
Greater than the time difference threshold under external area error operating condition, and it is less than the time difference in area under maximum protection range position fault condition,
Then determine that the distal end in area occurs for the confusion region failure, or, when the zero crossing number of the line line wave after analyzing is big
When adjusting zero crossing number, then determine that the distal end in area occurs for the confusion region failure；
Otherwise, it is determined that the proximal end outside area occurs for the confusion region failure.
7. a kind of guard method of dead-zone fault in DC grid according to claim 5 or 6, is characterized in that: described
Adjusting zero crossing number is adjusted by the zero number that the time window theoretically can at least capture.
8. a kind of guard method of dead-zone fault in DC grid according to claim 7, is characterized in that: the adjusting
Zero crossing number, which is equal to, adds default nargin zero crossing by the zero number that the time window theoretically can at least capture
Number.
9. a kind of protection system of the dead-zone fault in DC grid, is characterized in that: comprising the following modules,
Dc circuit breaker control module is used to determine that confusion region failure occurs for route when the local main protection in DC grid
When, then local dc circuit breaker movement is controlled, the electric current in the local dc circuit breaker is made to be transferred to transfer branch by main branch
Road；
Criterion generation module is used to obtain the line line wave in route, based on the line line wave building time difference criterion and
Zero crossing criterion；
Abort situation judgment module is used to the time difference criterion and the zero crossing criterion carrying out logic or operation, root
The specific location that the confusion region failure occurs is judged according to the result of logic or operation；
The dc circuit breaker control module occurs if being also used to the confusion region failure in area when distal end, to described
Ground dc circuit breaker is issued to jump and be enabled, and disconnects the local dc circuit breaker；If the proximal end outside area occurs for the confusion region failure
When, then the local dc circuit breaker movement is controlled, is transferred to the electric current in the local dc circuit breaker by transfer branch
Main branch.
10. a kind of computer storage medium, it is characterised in that: including at least one instruction, be performed realization in described instruction
Method and step as claimed in any one of claims 1 to 8.
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| CN113381390A (en) * | 2021-05-13 | 2021-09-10 | 广东工业大学 | Method for controlling local direct current breaker to act during communication failure between direct current power grid stations |
| CN114113911A (en) * | 2021-12-06 | 2022-03-01 | 国网山东省电力公司电力科学研究院 | Fault waveform-based fault type discrimination method and discrimination system |
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