CN109917226A - Double sampled rate distribution line fault point positioning method based on wavelet analysis - Google Patents
Double sampled rate distribution line fault point positioning method based on wavelet analysis Download PDFInfo
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- CN109917226A CN109917226A CN201910230808.1A CN201910230808A CN109917226A CN 109917226 A CN109917226 A CN 109917226A CN 201910230808 A CN201910230808 A CN 201910230808A CN 109917226 A CN109917226 A CN 109917226A
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Abstract
The invention discloses a kind of double sampled rate distribution line fault point positioning method based on wavelet analysis, phase correlation calculating is carried out to the phase current waveform of low sampling rate measuring device acquisition, start the recording function of high sampling rate measuring device when determining that failure occurs, then the phase current waveform of high sampling and measuring device acquisition is handled, fault point is accurately positioned according to D type traveling wave method.The present invention solves the problems, such as the unreliable of traditional amplitude triggering recording by carrying out correlation coefficient calculating to Wave data.And relatedness computation only is carried out to low sampling rate data, calculation amount is effectively reduced, failure wave-recording triggering speed is improved.Window is small when high sampling rate measuring device used sampling simultaneously, does not depend on large storage capacity, significantly reduces the cost of distribution detection device.
Description
Technical field
The present invention relates to distribution network line fault diagnostic techniques field, specifically a kind of double sampled rate based on wavelet analysis
Distribution line fault point positioning method.
Background technique
With economic continuous development, requirement of the user to power supply quality is increasingly improved.Power distribution network is as direct in power grid
There is significant impact in the part interacted with user to the electricity consumption experience of user, and the fault location of distribution is just particularly important.And
Country's power distribution network mostly uses neutral non-effective grounding mode at present, and topological structure is complicated, and branch is more；Earth-fault current is small,
Fault location is more difficult.Raising with people to distribution automation level requirement, more there is an urgent need to fundamentally solve to match
The fault-location problem on cable road.
Current distribution line Fault Locating Method both at home and abroad mainly faulty indicator method, impedance method and traveling wave method.It compares
In fault detector method and impedance method, traveling wave method is influenced by line parameter circuit value, system operation mode, transition resistance and fault type
Small, locating speed is fast, and it is currently the hot spot of distribution line fault location research that accuracy is high.But the route of power distribution network complexity
Structure and numerous branches lead to that fault traveling wave amplitude is small, attenuation distortion is big, cause difficulty to the positioning of Distribution Network Failure.And mesh
Preceding fault traveling wave detection device leads to the erroneous judgement of failure and fails to judge usually using traveling wave amplitude as failure criterion, it is more difficult to obtain
Preferable fault traveling wave recording waveform；Traveling wave method failure is accurately positioned more demanding to detection device sample rate simultaneously, to equipment
Hardware performance requirements are larger, using not extensive in the case where the control of power distribution network low cost.
Summary of the invention
It is an object of the invention to overcome above-mentioned the deficiencies in the prior art, propose a kind of based on the double sampled of wavelet analysis
Rate distribution line fault point accurate positioning method.
The principle of the present invention is as follows:
When power circuit breaks down, due to the mutation of fault point voltage, will occur transient state travelling wave process on the line.Electricity
The traveling wave phenomenon of line of force road can be described with the telegraph equation established on the basis of distributed parameter transmission line model, along line voltage
It include two traveling-wave components of forward and reverse with electric current, frequency domain form can indicate are as follows:
In formula, U+(x, ω) and I+(x, ω) respectively indicates the voltage and current traveling wave propagated along x positive direction； U-(x,ω)
And I-(x, ω) respectively indicates the voltage and current traveling wave propagated along x positive direction.
The moment that failure occurs, fault point generates initial traveling wave, and propagates towards route both ends.As shown in Figure 1, setting event
It is respectively T that barrier initial row wave, which was gushed with the time at the arrival end route M identical spread speed v and N-terminal,MWith TN, then both exist with
Lower relationship:
In formula, LMFWith LNFRespectively the end route M is at a distance from N-terminal to fault point；L is the length of route MN.
By solving above-mentioned equation group it can be concluded that fault point to route both ends distance LMF、LNFWith TM、TNRelationship, such as formula
(1) shown in:
In order to obtain the arrival time of traveling wave, singularity analysis is carried out with regard to particularly significant to travelling wave signal.WAVELET TRANSFORM MODULUS
There are corresponding relationships for maximum and Signal Singularity, determine that traveling wave arrival time becomes the master in engineer application by wavelet transformation
Means are wanted, but wavelet analysis result is influenced by factors such as the types, sample rate and decomposition scale of wavelet basis, wavelet transformation is resonable
By above there is unlimited a variety of wavelet basis, if being unable to its feature of analyzing in detail and combining the suitable wavelet basis of travelling wave signal feature selecting
Function is just difficult to obtain satisfied effect.For travelling wave ranging application, the selection of wavelet basis is particularly important, it is desirable that small echo
Base has symmetry, compact schemes, linear phase shift and high-order vanishing moment, uses cubic B-Spline interpolation in actual use more.
By placing measuring device at the node of distribution line, the initial traveling-wave waveform of failure is recorded；Then small echo is used
Analysis obtains the time that traveling wave reaches, then cooperates distribution topological diagram, can calculate the position of fault point, realize the essence of fault point
Determine position.
Technical solution of the invention is as follows:
Step S1, according to the phase current waveform of distribution each node low sampling rate measuring device acquisition, according to power frequency period P,
Certain time interval Q is taken, the phase to the phase current waveform I1 of time t to time (t+Q), with the time (t+P) to time (t+P+Q)
Current waveform I2 calculate according to formula (1) correlation coefficient:
Wherein, covariance of the Cov (I1, I2) for the first phase current waveform I1 and the second phase current waveform I2, Var | I1 | be
The variance of first phase current waveform I1, Var | I2 | it is the variance of the second phase current waveform I2；
Step S2 determines the numerical values recited of K:
When K is greater than given threshold, determine that failure does not occur, return step S1, and enable t=t+Q；
When K is less than or equal to given threshold, failure is determined, record the period of failure generation: (t+P) to (t+
P+Q), it is denoted as T, starts high sampling rate measuring device, record storage is carried out to the fault waveform of T period；
Step S3 carries out wavelet analysis to the fault waveform of T period, the initial wavefront of failure is found out, to obtain No. i
The arrival time T of the initial traveling wave of nodei, and determine according to the traveling wave amplitude measured the polarity of traveling wave, and by polarity of traveling wave with
The installing direction of measuring device obtains initial traveling wave direction mi；
Step S4 counts initial traveling wave direction miWith mjOpposite adjacent node j, k, is therefrom selected using calculated result in S3
Traveling wave arrival time T outj、TkThe sum of the smallest one group two end nodes as faulty line L；
Step S5 calculates the position of fault point on faulty line L, and formula is as follows:
Wherein LMFWith LNFRespectively the end route M is at a distance from N-terminal to fault point；L is the length of route MN；V is traveling wave
Spread speed.
Compared with prior art, the beneficial effects of the present invention are:
(1) distribution traveling wave amplitude is small, attenuation distortion is big, by using phase correlation, solves traditional equipment dependence
The unreliable problem of traveling wave amplitude triggering recording；
(2) correlation coefficient calculating only is carried out to low sampling rate Wave data, effectively reduces the calculation amount of equipment, improved
Failure wave-recording triggers speed；
(3) fault verification is realized not against high sampling rate measuring device, when reducing the sampling of high sampling rate measuring device
Window does not depend on large storage capacity, significantly reduces the cost of distribution detection device.
Detailed description of the invention
Fig. 1 is D type traveling wave method fault location schematic illustration
Fig. 2 is emulation distribution network system topological diagram
Fig. 3 is No. 1 node A phase current waveform figure
Fig. 4 is No. 1 nodal line line wave waveform diagram
Fig. 5 is the emulation initial traveling wave directional diagram of each node of distribution network system
Specific embodiment
The required fault waveform of the present invention contains low, high two in distribution line distributed measurement device, device
The measuring device of kind sample rate.Three groups of measuring devices of each fault location node installation, real-time synchronization acquire route three-phase current.
According to the Fault Locating Method of invention, in 10kV power distribution network analogue system, singlephase earth fault is set.System knot
Composition is as shown in Fig. 2, be respectively labeled as No. 1 to No. 6 node to 6 selected nodes in figure.The low sampling frequency that measuring device uses
Rate is 20KHz, and high sample frequency is 1MHz.Occurs for failure for 0.055s the moment, and fault type is metallic earthing failure.
Embodiment citing pinpoint for fault point:
Step S1, the phase current data measured according to low sampling rate measuring device take power frequency period P=by taking Fig. 3 as an example
0.02s, time interval Q=0.005s calculate the degree of correlation K of corresponding I1 Yu I2 waveform since t=0；
Step S2 determines K and the size of given threshold 0.99.If K > 0.99, determines that failure does not occur, return to step
Rapid S1, and enable t=t+0.005 (s)；If K > 0.99, failure period of right time T:(t+0.02 is recorded) to (t+0.025), to height
The waveform of sample rate measuring device T period carries out recording storage.
Step S3 carries out wavelet analysis to the phase current waveform of the high sampling rate measuring device acquisition of starting recording, with Fig. 4
For, obtain the arrival time T of No. 1 to No. 6 initial traveling wave of node1~T6With polarity of traveling wave, as shown in table 1.And by polarity of traveling wave
Initial traveling wave direction is obtained with the installing direction of measuring device, as shown by the arrows in Figure 5；
The initial traveling wave arrival time of each node of table 1 and polarity of traveling wave
Step S4 counts initial traveling wave direction miWith mjOpposite adjacent node i, j, and therefrom calculate and select traveling wave arrival
Moment Ti、TjThe sum of it is one group the smallest, as a result No. 1 node and No. 2 nodes.Therefore using No. 1 node and No. 2 nodes as failure
Two end nodes of route L.
Step S5, according to formula (2):
By v=2.95*108M/s, L=20km, TM=0.055015s, TN=0.055049s brings formula (2) into, calculates
LMF=5.005km, LMF=14.995km.That is fault point is located on the right side of No. 1 node at 5.005km on faulty line L.Practical event
Hinder position to be located on the right side of No. 1 node at 5km, therefore position error is 0.005km.
Claims (1)
1. a kind of double sampled rate distribution line fault point positioning method based on traveling wave method, it is characterised in that the method includes with
Lower step:
Step S1 takes one according to power frequency period P according to the phase current waveform of each node low sampling rate measuring device acquisition of distribution
It fixes time and is spaced Q, the phase current to the phase current waveform I1 of time t to time (t+Q), with the time (t+P) to time (t+P+Q)
Waveform I2 calculate according to formula (1) correlation coefficient:
Wherein, covariance of the Cov (I1, I2) for the first phase current waveform I1 and the second phase current waveform I2, Var | I1 | it is first
The variance of phase current waveform I1, Var | I2 | it is the variance of the second phase current waveform I2；
Step S2 determines the numerical values recited of K:
When correlation coefficient K is greater than given threshold, determine that failure does not occur, return step S1, and enable t=t+Q；
When correlation coefficient K is less than or equal to given threshold, failure is determined, record the period of failure generation: (t+P)
To (t+P+Q), it is denoted as T, starts high sampling rate measuring device, record storage is carried out to the fault waveform of T period；
Step S3 successively carries out calculating analysis from all nodes, remember present analysis node be No. i-th node, i=1,2 ...,
Wavelet analysis is carried out to the fault waveform of T period, the initial wavefront of failure is found out, obtains No. i-th initial traveling wave of measuring node
Arrival time, be denoted as " Ti", and determine according to the traveling wave amplitude measured the polarity of traveling wave, by polarity of traveling wave and measuring device
Installing direction obtain the initial traveling wave direction at No. i-th node, be denoted as mi, then by TiWith miIt is stored；
Step S4 is not repeatedly successively chosen at two nodes adjacent in network topology, if it is in S3 in all nodes
Number point than being jth number and kth number, then arrival time of jth node and kth node corresponding initial traveling wave in S3
Respectively Tj、Tk, initial traveling wave direction is then respectively mjWith mk；
Step S5 counts initial traveling wave direction mj′With mk′Opposite adjacent node j ', k ', therefrom selects traveling wave arrival time Tj′、
Tk′The sum of the smallest one group both ends node M and N as faulty line L, and the traveling wave arrival time of the two o'clock is denoted as TMWith
TN；
Step S6 calculates the position of fault point on faulty line L, and formula is as follows:
Wherein LMFWith LNFRespectively the end route M is at a distance from N-terminal to fault point；L is the length of route MN；V is that traveling wave propagates speed
Degree.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112611944A (en) * | 2020-11-27 | 2021-04-06 | 武汉三相电力科技有限公司 | Method and system for monitoring and early warning abnormal discharge of direct-current transmission line on line |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109387744A (en) * | 2018-12-17 | 2019-02-26 | 国网山东省电力公司电力科学研究院 | Distribution line fault point positioning method and device based on singular value decomposition |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109387744A (en) * | 2018-12-17 | 2019-02-26 | 国网山东省电力公司电力科学研究院 | Distribution line fault point positioning method and device based on singular value decomposition |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112611944A (en) * | 2020-11-27 | 2021-04-06 | 武汉三相电力科技有限公司 | Method and system for monitoring and early warning abnormal discharge of direct-current transmission line on line |
| CN112611944B (en) * | 2020-11-27 | 2024-07-26 | 武汉三相电力科技有限公司 | DC transmission line abnormal discharge online monitoring and early warning method and system |
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Application publication date: 20190621 |