CN104820165B - A kind of same-tower double-circuit direct-current transmission line fault line selection based on monopole information - Google Patents
A kind of same-tower double-circuit direct-current transmission line fault line selection based on monopole information Download PDFInfo
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Abstract
The invention discloses a kind of same-tower double-circuit direct-current transmission line fault line selection based on monopole information, comprise the steps of：1st, the voltage variety of four polar curves is calculated；2nd, if upper strata, polar curve is transferred to step 3 if meeting condition, and step 4 is transferred to if lower floor's polar curve meets condition；If the 3, low-frequency harmonics amplitude meets minimum value requirement, continue to ask low frequency and high-frequency harmonic Amplitude Ration, ratio is judged as this pole line fault more than 1, otherwise this pole of locking traveling-wave protection；4th, voltage variety delay is sampled, if only detecting a mutation wave head in data processing time window, is transferred to step 3；If at least two mutation wave heads are detected in data processing time window; compare continuous two wave head polarity and magnitude relation, if polarity is all positive polarity and magnitude relation meets certain multiple condition, be judged as the non-near terminal fault in this polar curve road; otherwise, this pole of locking traveling-wave protection.Have the advantages that sensitivity is high, quick-action is strong and be not susceptible to erroneous judgement.
Description
Technical field
The present invention relates to a kind of power system HVDC Transmission Technology, more particularly to a kind of common-tower double-return based on monopole information
Direct current transmission line fault selection method.
Background technology
Chinese natural energy resources skewness and the energy and the asymmetric present situation of population distribution so that D.C. high voltage transmission
Technology has open application prospect at home.Compared to high-voltage AC transmission technology, there is high voltage dc transmission technology unit to make
Valency is low, transimission power is big, both ends exchange uses D.C. high voltage transmission without running simultaneously, controlling to adjust the advantages that rapid
Technology is advantageous to improve economic indicator, technical indicator, reliability of operation and flexibility of scheduling of power system etc..
In order to ensure the safe and reliable operation of power system, the protection of HVDC transmission line is significant.Mesh
Before, HVDC transmission line protection in the world uses traveling-wave protection mostly, utilizes the voltage electricity for traveling to protection point
Popular wave characteristic carries out fault distinguishing, and protection detection time is short.But the increase and transmission of electricity corridor due to transmission line capability are nervous,
Common-tower double-return DC power transmission line just increasingly puts into operation.Common-tower double-return DC line has two loop line roads, each loop line Lu Douyou
Positive pole, negative pole, any pole line failure all can be to other three pole line influence failure electrical quantity in traveling wave communication process.
Therefore, failure and non-faulting polar curve how are dependably distinguished from, it is heavy to closing for the DC line traveling-wave protection based on transient
Will.Yet with common-tower double-return DC power transmission line without transposition, cause to be coupled out during different polar curve earth faults each
The polarity of line mould and ground line wave component on each polar curve has differences with amplitude, and velocity of wave also differs, this considerably increases
The difficulty of the existing traveling-wave protection scheme identification failure polar curve based on monopole line information structure.If only by improving setting valve
Mode solves the above problems, and the sensitivity to protection is impacted, it is therefore necessary to make full use of common-tower double-return DC line
Fault traveling wave propagating characteristic is solved.
The content of the invention
The shortcomings that it is an object of the invention to overcome prior art and deficiency, there is provided a kind of same tower based on monopole information is double
Direct current transmission line fault selection method is returned, the same-tower double-circuit direct-current transmission line fault line selection is directed to common-tower double-return direct current
The different fault transient property difference of transmission line of electricity levels polar curve, upper strata polar curve and lower floor's polar curve are realized using the method for combination
Failure line selection purpose.Suitable for existing common-tower double-return DC power transmission line, sensitivity is high, and quick-action is strong, is not susceptible to miss
Sentence, tolerance transition resistance ability also increases.
The purpose of the present invention is achieved through the following technical solutions：A kind of common-tower double-return DC transmission line based on monopole information
Road fault-line selecting method, is comprised the steps of：
(1) a certain particular moment instantaneous voltage before current time is taken to pass through the electricity at current time as reference quantity
Pressure instantaneous value subtracts reference quantity and obtains the voltage variety of four polar curves.Wherein four polar curves are represented with 1P, 1N, 2P, 2N, 1P,
2N is in the upper strata of same shaft tower, the lower floor of 1N, 2P in same shaft tower.1P, 1N are respectively electrode line, the negative pole on the first loop line road
Line, 2P, 2N are respectively the electrode line on the second loop line road, negative line, then the voltage variety of four polar curves is respectively Δ u1P、Δ
u1N、Δu2P、Δu2N。
(2) the voltage change ratio du of every polar curve is calculated1P/dt、du1N/dt、du2P/dt、du2N/ dt, while by 1P, 2P pole
The voltage change ratio of line is multiplied by -1, to ensure that reference value is positive polarity.The voltage change ratio for calculating acquisition is entered with threshold value
Row compares, and is shown below：
du/dt≥duset/ dt,
1P, 2N polar curve meet that condition is transferred to step (3) at the middle and upper levels for it, and lower floor's 1N, 2P polar curve meets that condition is transferred to step
(4)。
(3) preserve and meet t at the time of step (2) conditional1, voltage variety is delayed tdeSampled, pass through time-frequency
Analytic function extracts moment t1The low-frequency harmonics amplitude W at placeLWith high-frequency harmonic amplitude WH, then data are compared as follows：
Meet that above formula is then judged as this pole line fault, otherwise the traveling-wave protection of this pole of locking.
(4) voltage variety is delayed tdeSampled, wave head is extracted using with step (3) identical time frequency analysis function
Polarity and amplitude.Preserve mutation wave head number n.If only detecting a mutation wave head in data processing time window, step is transferred to
Suddenly (3)；If detecting at least two mutation wave heads in data processing time window, the polarity and amplitude of more continuous two wave heads
Relation, if meeting following formula：
Then it is judged as the non-near terminal fault in this polar curve road, no this pole of person's locking traveling-wave protection.Wherein vmaxnTo be mutated wave head mould
Maximum.
Preferably, in step (1), the voltage variety of described four circuits is before current instantaneous value subtracts 10ms
Value, to ensure that what line voltage distribution in the 10ms after line failure subtracted is the steady-state value before failure occurs, obtain circuit
Voltage failure amount, is calculated using following formula：
Wherein, u1P(t) represent polar curve 1P in the instantaneous voltage of t, Δ u1PRepresent circuit 1P after protection starts
Voltage jump amount, the rest may be inferred by analogy for it, and Δ t=10ms is the time interval of current time and particular moment.
Preferably, in step (2), the method for calculating voltage change ratio is to take the maximum of three sampled point differential values, with
Exemplified by 1P, it is shown below：
Wherein, td1For sampling time interval.In order to obtain the numerical value of positive polarity, the voltage variety of 1P, 2P polar curve is multiplied
To calculate rate of change again after -1.
Preferably, in step (3), preservation meets t at the time of step (2) conditional1, by taking 1P polar curves as an example, voltage is become
Change amount Δ u1P(t) be delayed tde=3td1Afterwards using time frequency analysis function extraction harmonic content.Time-frequency material calculation is td2, at data
Reason time window length is T=Ntd2, N >=100.Will output Δ u after time frequency analysis is handled1P(t) time-frequency matrixRow vector represents discrete time-domain coordinate in matrix, and column vector represents discrete frequency domain coordinate, matrix element amplitude table
Show the corresponding harmonic amplitude size at corresponding moment.Extract matrixMiddle t1The column vector at moment, low-order harmonic crest meter
Formula is：
Higher hamonic wave amplitude calculating formula is：
Preferably, in step (4), by taking 1N polar curves as an example, by voltage variety Δ u1N(t) be delayed tde=3td1Phase is used afterwards
It is T to extract wave head polarity and amplitude, data processing time window length with time frequency analysis function.Being mutated wave head modulus maximum is：For extracting method to take a matrix wherein row element to carry out derivation to the time, the point that derivative is zero is office
Portion's maximum point, that is, be mutated wave head.If extract f1Row element, then it is mutated wave head and corresponds to moment calculating formula and be：
Preserve mutation wave head number, polarity and amplitude information.If continuous two mutation wave head polarity is just, and second
Individual wave head amplitude is more than K with first wave head Amplitude Rationdown, then it is judged as this pole line fault, otherwise this pole of locking traveling wave is protected
Shield.
The present invention carries out failure line selection from lower floor's polar curve to upper strata polar curve using different methods, takes full advantage of not homopolarity
The fault transient feature of line, and only make use of monopolar line voltage transient information, in step (4), during described data processing
Between window only need 1 millisecond.
The purpose of the present invention can also be realized by following scheme：Calculate this polar curve road voltage variety；Calculate this polar curve
Road voltage change ratio；Judge whether line voltage distribution rate of change meets minimum conditions, satisfaction is then extracted by time frequency analysis function
Voltage variety time-frequency characteristics；Upper strata polar curve extraction low-frequency harmonics amplitude and high-frequency harmonic amplitude, if low-frequency harmonics amplitude meets
Minimum value requires and low high-frequency harmonic Amplitude Ration is more than 1, then judges this pole line fault；It is mutated in lower floor's polar curve extraction time window
Wave head number, polarity and amplitude information, if mutation wave head number is 1, extraction low-frequency harmonics amplitude and high-frequency harmonic amplitude, if low
Frequency harmonic amplitude meets minimum value requirement and low high-frequency harmonic Amplitude Ration is more than 1, then judges this polar curve road near terminal fault, if mutation
Wave head number is more than 1, and continuous two wave head polarity is all positive polarity, and second wave head amplitude and first wave head Amplitude Ration are big
In Kdown, then it is judged as the non-near terminal fault in this polar curve road.
The principle of failure line selection of the present invention is as follows：It is similar with the failure Electromagnetic Coupling Characteristic of single time DC line, it is double with tower
Returning four polar curves of DC line can intercouple out four modulus traveling-waves in failure.Sent out according to electromagnetic coupled analysis result
Existing, the fault transient characteristic of the fault transient characteristic of upper strata polar curve and lower floor polar curve simultaneously differs, therefore is constructing failure line selection
Need to study respectively in method.Common-tower double-return DC power transmission line mould is built using PSCAD/EMTDC electromagnetic transient simulation softwares
Type is as follows to analysis of simulation result：
1st, upper strata 1P polar curves fault transient characteristic；
Set failure to emulate in different circuits distance 1P polar curves, obtain four line voltage variable quantity comparison diagrams such as
Shown in (Fig. 3 (a) (b)).In Fig. 3 (a), solid line is 1P line voltage waveforms, and dotted line is the 2N line voltage waveforms with layer.1P
Line voltage wave head amplitude is larger, and amplitude is gentle after ripple, therefore low-order harmonic content is larger.2N line voltages waveform occurs one
Impulse wave head, amplitude very little after ripple, wave head is mainly higher harmonic content.Fig. 3 (b) is to layer 1N polar curves and 2P line voltage ripples
Shape figure, voltage change amplitude is smaller, therefore low-order harmonic content is also smaller.To sum up waveform characteristic is analyzed, and is proposed humorous with low order
Ripple content is used as upper strata polar curve failure as fault initiating additional criteria, then using low-order harmonic content and higher harmonic content ratio
Route selection criterion, it is possible to prevente effectively from layer to traveling-wave protection malfunction caused by pole failure and thunderbolt disturbance.
2nd, lower floor 1N polar curves fault transient characteristic；
Fault simulation is set in different circuits distance to 1N polar curves, obtains four line voltages variable quantity oscillograms such as (Fig. 4
(a) (b)) shown in.In Fig. 4 (a), solid line is 1N line voltage waveforms, and dotted line is the 2P line voltage waveforms with layer.1N polar curves
Voltage has two voltage wave heads in the same direction, and 2P line voltages have two reverse voltage wave heads, and two voltage wave head amplitudes have
Certain proportionate relationship.Fig. 4 (b) is to layer line voltage oscillogram, and the voltage wave head on polar curve is unsatisfactory for certain ratio and closed
System.In the case of circuit top failure, the life of voltage wave hair overlaps, and can not compare the polarity and amplitude of continuous two voltage wave heads
Relation, but 1N line voltage low-frequency harmonics contents are larger, remaining polar curve low-frequency harmonics content is smaller, in this case can be according to
Failure line selection is carried out by frequency characteristic difference.It is low because 2P line voltage coupling amounts are larger in the line in the case of far-end fault
Subharmonic content is also larger, therefore can not effectively distinguish 1N polar curves failure and 2P polar curve failures by frequency characteristic.
Analyzed according to waveform characteristic, if circuit only detects a mutation wave head in set time window, in this case
The extremely low subharmonic content of failure is higher than non-faulting pole, therefore is transferred to step (3) and carries out failure line selection.If circuit is in set time window
At least two mutation wave heads are inside detected, 1N polar curves are close with the low-order harmonic content of 2P polar curves in this case, can not basis
Step (3) carries out failure line selection, therefore is transferred to step (4) and carries out failure line selection using wave head polarity and magnitude relation.When passing through
The polarity of frequency analysis function extraction mutation wave head and contained harmonic amplitude.
Because the fault transient characteristic of upper strata polar curve differs with lower floor polar curve, therefore the present invention uses combined fault route selection
Method, different failure line selection schemes is formulated levels polar curve respectively, improve sensitivity of the protection to Fault Identification.Upper and lower two layers
The fault-line selecting method of polar curve can not be used mutually.
Setting principle；
Adjusting voltage change ratio criterion definite value needs to consider the influence of external area error.Because line end is equiped with flat ripple electricity
Anti- device, the traveling wave for transmitting external area error are weakened smoothened, rate of change reduction.Therefore voltage change ratio criterion definite value is to hide
Maximum rate of change caused by opening external area error and set.The sampling interval for calculating rate of change is td1, when voltage change ratio exceedes door
Starting protection criterion during threshold value.
After upper strata 1P, 2N polar curve meets voltage change ratio criterion, fault initiating moment t is preserved1And enter failure line selection ring
Section.In order to obtain the Time-Frequency Information of complete mutation wave head, voltage variety is delayed tdeCarry out time-frequency conversion again afterwards.Application when
Frequency analysis function has to accurately extract harmonic amplitude.In order to obtain the high-frequency harmonic information of mutation wave head, data sampling rate
Should be as high as possible, sampled data is as more as possible.The time-frequency material calculation t that the present invention usesd2=0.01ms, sampled data output N=
100, time window T=1ms, but it is not limited to this.Voltage variety can export the corresponding time respectively after time frequency analysis is handled
N × N time-frequency matrixes of windowMatrix row vector t represents discrete time-domain coordinate, and column vector f is represented
Discrete frequency domain coordinate.Before whereinThe positive frequency harmonic amplitude coefficient of row matrix element representation, afterRow represents negative frequency harmonic amplitude system
Number.Because positive and negative frequency amplitude is equal, therefore before need to only takingRow matrix element is calculated.T in matrix1Arranged corresponding to moment to
Amount represents harmonic content distribution situation contained by the moment wave head, and overtone order is from low toward high growth.Before takingCapable matrix element
Sum is low-order harmonic amplitude WL, takeRow is extremelyCapable matrix element sum is higher hamonic wave amplitude WH.Low-order harmonic width
The threshold value W of valueLsetSetting principle is that minimum low-order harmonic amplitude during critical transition resistance ground connection occurs for circuit.WLIt is more than
WH, therefore ratio KupMinimum value is 1.
After lower floor polar curve 1N, 2P meet voltage change ratio criterion definite value, handled by identical time frequency analysis and obtain time-frequency square
Battle arrayExtract a wherein row element in matrix and derivation is carried out to the time, obtain mutation wave head information.
If detecting two or more mutation wave heads, more continuous two wave head polarity and amplitude, by taking 1N polar curves as an example, its this pole
Two wave head polarity are that just, and second wave head amplitude is more than 5, therefore K with first wave head Amplitude Ration during failuredownIt is whole
Principle is determined to meet line mould ripple uP3With line mould ripple uP2Amplitude Ration, according to calculate data may be configured as 5 times.
The present invention is had the following advantages relative to prior art and effect：
Firstth, quick-action is strong；The present invention only need to make use of shorter failure wave head (in 1ms) time-frequency transient characterisitics, can
Quick identification failure polar curve, be advantageous to DC line protection and excision failure is acted within the shorter time.
Secondth, it is strong to be resistant to transition resistance ability；The time-frequency characteristics ratio relation of the invention for mainly utilizing fault traveling wave, can disappear
Except the influence of transition resistance, as long as voltage change ratio meets fault initiating criterion, failure line selection can be accurately carried out.
3rd, reliability is high；The present invention takes full advantage of the fault transient characteristic of common-tower double-return DC line, targetedly
Failure line selection differentiation is carried out to different circuits, the traveling-wave protection of non-faulting polar curve can reliably be failure to actuate.
4th, the present invention only needs this polar curve road voltage variety information, can meet together without communication port between circuit
Tower double back DC line fault route selection function, possesses engineering application value.
Brief description of the drawings
Fig. 1 is upper strata polar curve fault-line selecting method flow chart.
Fig. 2 is lower floor's polar curve fault-line selecting method flow chart.
Fig. 3 (a) is line voltage waveform changing trend diagram in upper strata caused by 1-P polar curve failures.
Fig. 3 (b) is lower floor's line voltage waveform changing trend diagram caused by 1-P polar curve failures.
Fig. 4 (a) is lower floor's line voltage waveform changing trend diagram caused by 1N polar curve failures.
Fig. 4 (b) is line voltage waveform changing trend diagram in upper strata caused by 1N polar curve failures.
Fig. 5 (a) is 1P polar curves failure and Δ u under 2N polar curve failures1PWave head comparison diagram.
Fig. 5 (b) is 1P polar curves failure and Δ u under 2N polar curve failures1PFrequency characteristic comparison diagram.
Fig. 6 (a) is 1N polar curves failure and Δ u under 2P polar curve failures1NWave head comparison diagram.
Fig. 6 (b) is 1N polar curves failure and Δ u under 2P polar curve failures1NFrequency characteristic comparison diagram.
Fig. 7 is 1N polar curves failure and Δ u under 2P polar curve failures1NWave head polarity comparison diagram.
Embodiment
With reference to embodiment and accompanying drawing, the present invention is described in further detail, but embodiments of the present invention are unlimited
In this.
Embodiment
As depicted in figs. 1 and 2, a kind of common-tower double-return direct current transmission line fault route selection combination based on monopole transient information
Method, comprise the steps of：
(1) as shown in Fig. 3 (a) and Fig. 3 (b), a certain particular moment instantaneous voltage before current time is taken as ginseng
Consider, subtracting reference quantity by the instantaneous voltage at current time obtains the voltage variety of four polar curves.Wherein four polar curves
Represented with 1P, 1N, 2P, 2N, 1P, 2N are in the upper strata of same shaft tower, the lower floor of 1N, 2P in same shaft tower.1P, 1N are respectively first
The electrode line on loop line road, negative line, 2P, 2N are respectively the voltage change of the electrode line on the second loop line road, negative line, then four polar curves
Change amount is respectively Δ u1P、Δu1N、Δu2P、Δu2N.It is as follows to calculate formula：
Wherein, u1P(t) represent polar curve 1P in the instantaneous voltage of t, Δ u1PRepresent circuit 1P after protection starts
Voltage jump amount, the rest may be inferred by analogy for it, and Δ t=10ms is the time interval of current time and particular moment.
(2) the voltage change ratio du of every polar curve is calculated1P/dt、du1N/dt、du2P/dt、du2N/ dt, while by 1P, 2P pole
The voltage change ratio of line is multiplied by -1, to ensure that reference value is positive polarity.The voltage change ratio for calculating acquisition is entered with threshold value
Row compares, and is shown below：
du/dt≥duset/ dt,
1P, 2N polar curve meet that condition is transferred to step (3) at the middle and upper levels for it, and lower floor's 1N, 2P polar curve meets that condition is transferred to step
(4)。
(3) as shown in Fig. 5 (a) and Fig. 5 (b), preservation meets t at the time of step (2) conditional1, voltage variety is prolonged
When tdeSampled, moment t is extracted by time frequency analysis function1The low-frequency harmonics amplitude W at placeLWith high-frequency harmonic amplitude WH, then
Data are compared as follows：
Meet that above formula is then judged as this pole line fault, otherwise the traveling-wave protection of this pole of locking.
(4) as shown in Fig. 6 (a) and Fig. 6 (b), voltage variety is delayed tdeSampled, using identical with step (3)
Time frequency analysis function extraction wave head polarity and amplitude information.If a mutation ripple is only detected in data processing time window
Head, it is transferred to step (3)；If detecting at least two mutation wave heads in data processing time window, more continuous two wave heads
vmax.n、vmax.n+1Polarity and magnitude relation, if meeting following formula：
Then it is judged as the non-near terminal fault in this polar curve road, otherwise the traveling-wave protection of this pole of locking.
As shown in fig. 7, using PSCAD/EMTDC simulation softwares, the systematic parameter of DC engineering is crossed with reference to small stream Lip river, structure is together
Tower double back DC transmission system model.Common-tower double-return double back DC power transmission line model uses to be built according to frequency parameter model, circuit
Total length 1254km, the trapezoidal distribution of overhead line structures parameter multiple-circuit on same tower, upper strata polar curve are 1P, 2N, lower floor's polar curve be 1N,
2P, G1, G2 are respectively ground wire, and the horizontal range l3 of two ground wires is 28.4m, and polar curve 1P and 2N horizontal range l1 are 14.5m,
Polar curve 1N and 2P horizontal range l2 are 19.2m, and the distance h1 on lower floor's polar curve and ground is 18m, upper strata polar curve and lower floor's polar curve
Vertical range h2 be 15m, the vertical range h3 of ground wire and upper strata polar curve is 22m.In addition, the cross-line depth of transmission line of electricity is
16m, the cross-line depth of ground wire is 11m.Then, on the basis of DC transmission system model, according to same tower proposed by the present invention
Double back direct current transmission line fault route selection combined method, voltage variety computing module, voltage change are built based on every polar curve road
Rate computing module, time frequency analysis module.Wherein time frequency analysis module application to the Time-Frequency Tool Box in MATLAB softwares, this
Invention is applied exemplified by S-transformation time frequency analysis function.The methods of being recombinated using function improves the time frequency analysis of time frequency analysis function
Can, and be applied in same-tower double-circuit direct-current transmission line fault line selection and fall within that the present invention relates to content.Time frequency analysis mould
Root tuber plays difference in functionality according to levels polar curve, and the calculating frequency of time frequency analysis module is 100kHz.Every polar curve is existed respectively
Apart from rectification side difference circuit distance, short trouble, including metallic earthing failure and 300 Ω transition resistance earth faults are set.
Because two loop line roads are symmetrical, therefore a loop line road failure line selection result is only provided, as shown in table 1 and table 2, table 1 is 1-P poles
Line failure line selection result, table 2 are 1-N polar curve failure line selection results.
Table 1
Table 2
300 Ω transition resistance ground fault conditions occur with circuit herein to verify fault-line selecting method.In 300 Ω
When transition resistance is grounded, the minimum 102kV of circuit low-frequency harmonics content, to retain nargin, the sensitivity coefficient conduct less than 1 is multiplied by
Threshold value, by taking 90kV as an example.The sample rate of time frequency analysis processing is 100kHz, and sampling time window is 1ms.
Grey data sufficient criterion certification condition with thumb down in table.By the data of table 1 it can be found that 1P polar curves are on this polar curve road
During failure, voltage change ratio, low-frequency harmonics amplitude and low high-frequency harmonic Amplitude Ration are satisfied by failure line selection requirement, make traveling-wave protection
Action message.During 1N polar curve metallicity failures, the voltage change ratio of 1P polar curves sensing meets threshold value requirement, near terminal fault
The low-frequency harmonics amplitude of sensing have also exceeded 90kV, but because low high-frequency harmonic Amplitude Ration is less than 1, therefore traveling-wave protection is reliable not
Action.During 2P polar curve failures, the voltage change ratio of 1P polar curves sensing is unsatisfactory for threshold value requirement, and protection does not start.2N polar curves are near
When holding failure, voltage change ratio is negative polarity, and protection does not start, and when away near terminal fault, low high-frequency harmonic Amplitude Ration is less than
1, therefore protection is reliably failure to actuate.In 300 Ω transition resistance earth faults, due to failure sensing amount very little between polar curve, because
This is unlikely to cause false protection.
By the data of table 2 it can be found that 1N polar curves are in circuit near terminal fault, 1 mutation is only detected in sampling time window
Wave head, it can distinguish failure polar curve using low high frequency Amplitude Ration and perfect polar curve.1N polar curves are adopted when away from circuit near terminal fault
Detected in sample time window during at least two mutation wave heads, wherein 1N polar curves failure it is continuous two mutation wave head polarity be just,
And second wave head amplitude is more than K with first wave head Amplitude Rationdown=5, condition is not satisfied for remaining polar curve.Utilize wave head pole
Property with magnitude relation can accurately distinguish this pole failure with remaining to pole failure, protect action message.
Above-described embodiment is the preferable embodiment of the present invention, but embodiments of the present invention are not by the embodiment
Limitation, other any Spirit Essences without departing from the present invention with made under principle change, modification, replacement, combine, simplification,
Equivalent substitute mode is should be, is included within protection scope of the present invention.
Claims (6)
1. a kind of same-tower double-circuit direct-current transmission line fault line selection based on monopole information, it is characterised in that comprising following
Step：
(1) a certain particular moment instantaneous voltage before current time is taken to pass through the voltage wink at current time as reference quantity
Duration subtracts reference quantity and obtains the voltage variety of four polar curves；
(2) voltage change ratio of every polar curve is calculated, the voltage change ratio obtained will be calculated compared with threshold value, if on
Layer 1P, 2N polar curve meets that condition is then transferred to step (3), and step (4) is transferred to if lower floor's 1N, 2P polar curve meets condition；
(3) preserve and meet t at the time of step (2) conditional1, voltage variety is delayed tdeSampled, pass through time frequency analysis
Function extracts moment t1The low-frequency harmonics amplitude W at placeLWith high-frequency harmonic amplitude WH；If low-frequency harmonics amplitude meets minimum value requirement,
Continue to ask low frequency and high-frequency harmonic Amplitude Ration, ratio is judged as this pole line fault more than 1, and otherwise this pole of locking traveling wave is protected
Shield；
(4) voltage variety is delayed tdeSampled, wave head polarity is extracted using with step (3) identical time frequency analysis function
With amplitude；If only detecting a mutation wave head in data processing time window, step (3) is transferred to；If in data processing time
Detect at least two mutation wave heads in window, more continuous two wave head polarity and magnitude relation, if polarity be all positive polarity and
Amplitude Ration is more than or equal to definite value KdownCondition, then be judged as the non-near terminal fault in this polar curve road, otherwise, this pole of locking traveling wave protect
Shield.
2. the same-tower double-circuit direct-current transmission line fault line selection according to claim 1 based on monopole information, it is special
Sign is that in step (1), the calculation formula of voltage variety is：
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<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mo>-</mo>
<msub>
<mi>u</mi>
<mrow>
<mn>2</mn>
<mi>P</mi>
</mrow>
</msub>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>-</mo>
<mi>&Delta;</mi>
<mi>t</mi>
<mo>)</mo>
</mrow>
</mrow>
</mtd>
</mtr>
<mtr>
<mtd>
<mrow>
<msub>
<mi>&Delta;u</mi>
<mrow>
<mn>2</mn>
<mi>N</mi>
</mrow>
</msub>
<mo>=</mo>
<msub>
<mi>u</mi>
<mrow>
<mn>2</mn>
<mi>N</mi>
</mrow>
</msub>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mo>-</mo>
<msub>
<mi>u</mi>
<mrow>
<mn>2</mn>
<mi>N</mi>
</mrow>
</msub>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>-</mo>
<mi>&Delta;</mi>
<mi>t</mi>
<mo>)</mo>
</mrow>
</mrow>
</mtd>
</mtr>
</mtable>
</mfenced>
<mo>,</mo>
</mrow>
Wherein, u1P(t) represent polar curve 1P in the instantaneous voltage of t, △ u1PRepresent voltages of the circuit 1P after protection starts
Sudden Changing Rate, u2P(t) represent polar curve 2P in the instantaneous voltage of t, △ u2PRepresent that voltages of the circuit 2P after protection starts is dashed forward
Variable, △ t=10ms are the time interval of current time and particular moment；u1N(t) voltage transients of the polar curve 1N in t is represented
Value, △ u1NRepresent voltage jump amounts of the circuit 1N after protection starts, u2N(t) voltage transients of the polar curve 1N in t is represented
Value, △ u2NRepresent voltage jump amounts of the circuit 1N after protection starts.
3. the same-tower double-circuit direct-current transmission line fault line selection according to claim 1 based on monopole information, it is special
Sign is, in step (2), the computational methods of voltage change ratio are to take the maximum of three sampled point Backward divided difference numerical differentiation values
Value, the calculation formula for calculating 1P polar curves are：
<mrow>
<msub>
<mi>du</mi>
<mrow>
<mn>1</mn>
<mi>P</mi>
</mrow>
</msub>
<mo>/</mo>
<mi>d</mi>
<mi>t</mi>
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<mn>1</mn>
<mi>P</mi>
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<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>-</mo>
<msub>
<mi>t</mi>
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<mi>d</mi>
<mn>1</mn>
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<mi>t</mi>
<mrow>
<mi>d</mi>
<mn>1</mn>
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</mfrac>
<mo>,</mo>
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<mrow>
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<mn>1</mn>
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</mrow>
<mo>-</mo>
<msub>
<mi>u</mi>
<mrow>
<mn>1</mn>
<mi>P</mi>
</mrow>
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<mo>(</mo>
<mi>t</mi>
<mo>-</mo>
<mn>3</mn>
<msub>
<mi>t</mi>
<mrow>
<mi>d</mi>
<mn>1</mn>
</mrow>
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<mo>)</mo>
</mrow>
</mrow>
<msub>
<mi>t</mi>
<mrow>
<mi>d</mi>
<mn>1</mn>
</mrow>
</msub>
</mfrac>
<mo>}</mo>
<mo>,</mo>
</mrow>
Wherein, td1For sampling time interval, in order to obtain the numerical value of positive polarity, the voltage variety of 1P, 2P polar curve is multiplied by -1
Calculate rate of change again afterwards.
4. the same-tower double-circuit direct-current transmission line fault line selection according to claim 1 based on monopole information, it is special
Sign is, step (3) just for upper strata polar curve and section bottom polar curve failure situation, preserve meet step (2) conditional when
Carve t1, voltage variety is delayed tde=3td1Handled by time frequency analysis function, export a time-frequency matrix D△u(t, f), carry
Take t in matrix1Column element corresponding to moment, calculate low-frequency harmonics amplitude and high-frequency harmonic amplitude, and be compared, calculating formula with
Comparison expression is：
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<msub>
<mi>W</mi>
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<mn>10</mn>
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<msub>
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<mrow>
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<mi>&Delta;u</mi>
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<mi>W</mi>
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<mo>=</mo>
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<mo>&Sigma;</mo>
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<mrow>
<mn>2</mn>
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<mn>5</mn>
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<mi>f</mi>
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<mfrac>
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<mn>2</mn>
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</munder>
<msub>
<mi>D</mi>
<mrow>
<msub>
<mi>&Delta;u</mi>
<mrow>
<mn>1</mn>
<mi>P</mi>
</mrow>
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</msub>
<mo>,</mo>
<mi>f</mi>
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</mrow>
</mrow>
</mtd>
</mtr>
<mtr>
<mtd>
<mrow>
<msub>
<mi>W</mi>
<mi>L</mi>
</msub>
<mo>&GreaterEqual;</mo>
<msub>
<mi>W</mi>
<mrow>
<mi>L</mi>
<mi>s</mi>
<mi>e</mi>
<mi>t</mi>
</mrow>
</msub>
</mrow>
</mtd>
</mtr>
<mtr>
<mtd>
<mrow>
<mfrac>
<msub>
<mi>W</mi>
<mi>L</mi>
</msub>
<msub>
<mi>W</mi>
<mi>H</mi>
</msub>
</mfrac>
<mo>&GreaterEqual;</mo>
<mn>1</mn>
</mrow>
</mtd>
</mtr>
</mtable>
</mfenced>
<mo>,</mo>
</mrow>
Wherein, WLFor low-frequency harmonics amplitude, WHFor high-frequency harmonic amplitude；If WLMore than WLsetAnd WLWith WHRatio be more than 1, then it is defeated
Go out 1, this pole traveling-wave protection action, f represents discrete frequency domain coordinate, and N is sampled data output.
5. the same-tower double-circuit direct-current transmission line fault line selection according to claim 1 based on monopole information, it is special
Sign is, in step (4), just for lower floor's polar curve partial fault situation, using with step (3) identical time frequency analysis function
Number, polarity and the amplitude information of mutation wave head in extraction time window, if detecting, mutation wave head number is 1, is transferred to step
(3), if detecting mutation wave head number at least 2, the polarity and magnitude relation of more continuous two wave heads；If two ripples
Head polarity is positive polarity and the Amplitude Ration of second wave head amplitude and first wave head amplitude is more than or equal to definite value Kdown, then it is defeated
Go out 1, the traveling-wave protection of this pole acts, and comparison expression is：
<mrow>
<mfenced open = "{" close = "">
<mtable>
<mtr>
<mtd>
<mrow>
<msub>
<mi>v</mi>
<mrow>
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<mo>.</mo>
<mi>n</mi>
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<msub>
<mi>v</mi>
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<mo>.</mo>
<mi>n</mi>
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<mn>1</mn>
</mrow>
</msub>
<msub>
<mi>v</mi>
<mrow>
<mi>max</mi>
<mo>.</mo>
<mi>n</mi>
</mrow>
</msub>
</mfrac>
<mo>&GreaterEqual;</mo>
<msub>
<mi>K</mi>
<mrow>
<mi>d</mi>
<mi>o</mi>
<mi>w</mi>
<mi>n</mi>
</mrow>
</msub>
</mrow>
</mtd>
</mtr>
<mtr>
<mtd>
<mrow>
<mi>n</mi>
<mo>&GreaterEqual;</mo>
<mn>1</mn>
</mrow>
</mtd>
</mtr>
</mtable>
</mfenced>
<mo>,</mo>
</mrow>
Wherein,To be mutated wave head modulus maximum, extraction mutation wave head corresponds to moment tnCalculating formula be：f1What is represented is element line number.
6. the same-tower double-circuit direct-current transmission line fault line selection according to claim 1 based on monopole information, it is special
Sign is, in step (4), described data processing time window only needs 1 millisecond.
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| CN108627739B (en) * | 2017-03-17 | 2020-08-14 | 广州供电局有限公司 | Fault area determination method and system for full-line quick-action protection |
| CN108680823B (en) * | 2018-05-14 | 2021-01-12 | 南方电网科学研究院有限责任公司 | Detection method for single-pole grounding fault of direct-current overhead line |
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