CN104793106B - Distribution line fault section location method based on current break rate - Google Patents
Distribution line fault section location method based on current break rate Download PDFInfo
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Abstract
The invention discloses a kind of distribution line fault section location method based on current break rate, for earth fault, by analyzing phase current feature of the faulted phase current before failure generation is preceding and failure occurs to arc suppression coil to act, fault characteristic value is therefrom extracted, and is positioned using the waveform-shaped current mutation rate of overall process.The present invention only needs the faulted phase current of measurement circuitry, scheme is simple, strong applicability, the problem of faint fault current during the single-phase grounded malfunction in grounded system of low current of current generally existing, poor reliability, low sensitivity can be solved very well, disturbed while will not be introduced to system.
Description
Technical field
The present invention relates to distribution network line fault diagnostic method, specifically a kind of distribution line event based on current break rate
Hinder Section Location.
Background technology
According to statistics, in the process of running, the power outage caused by Distribution Network Failure accounts for total power outage for power system
More than 95%, wherein 70% accident is triggered by singlephase earth fault or bus-bar fault.And distribution neutral point is adopted extensively both at home and abroad
With non-effective earthing (small current neutral grounding) mode, to avoid occurring causing power failure during singlephase earth fault.For distribution
Singlephase earth fault, because fault characteristic value is faint, lacks reliable fault line selection and fault locating method always.With people to
The raising of automation level requirement, more in the urgent need to the fault-location problem for fundamentally solving distribution.
The Fault Locating Method that current domestic and foreign scholars are proposed is roughly divided into two classes：One is injecting signal, and two be to be based on
The section positioning of fault characteristic value.Injecting signal includes " S " injection method, alternating current-direct current and integrates injection method and parallel medium resistance method,
Such method increases the interference to system, and can not detect instantaneity and intermittent grounding fault.Based on fault characteristic value
Section positioning include zero mould electric current comparison method, section zero sequence admittance method, zero sequence reactive power direction method, based on difference of phase currents
Positioning, residual method of addition, traveling wave method etc., electrical power distribution automatization system mainly realizes FTU time synchronized using main website, to mistiming
Difference is at least several milliseconds.In the case, the method such as to compare no longer valid for the amplitude of transient signal, polarity, Waveform Correlation.
Observation understands that current method have ignored the profit to information before failure only using the data after failure generation
With.Meanwhile, most of localization methods only consider zero-sequence current information (needing three phase informations), high to transformer request, and information is obtained
Complexity is taken, and these methods will fail in the case of data phase shortage.
The content of the invention
It is an object of the invention to overcome above-mentioned the deficiencies in the prior art, it is proposed that a kind of distribution based on current break rate
Line fault Section Location.
The principle of the present invention：
If failure is mutually A phases, test point phase voltage is before failurePhase voltage is after failureBy Fig. 1, the two is apparent from
Meet
1) adjacent test point 1,2 is located at trouble point heteropleural (without branched line between test point), if test point 1 is located at trouble point
Upstream, test point 2 is located at trouble point downstream.
The phase current of test point 1 is before failure
In formula,For load current,It is A phases from test point 1 to the capacitance current of this line end, is represented by
In formula, C1AIt is A phases from test point 1 to the electric capacity of this line end.
Assuming that a cycle internal loading electric current is constant before and after failure occurs, the faulted phase current of test point 1 is after failure
In formula,Respectively A phases capacitance current and fault current.Wherein
Arc suppression coil offsets the inductive current produced using neutral point voltage during failure come bucking-out system capacitance current, ground connection
Point residual flow (fault current) is represented by
In formula, CΣFor the whole network line mutual-ground capacitor.Failure occur and in the arc suppression coil not operating period, presetting system arc blowout wire
Circle resistance is very big, and post-set arc suppression coils reactance is very big, all in all | ZL| very big, Section 2 can be neglected in formula.Then
Have
Similarly, before failure test point 2 phase current
The faulted phase current of test point 2 after failure
Analyzed more than, before failure, the difference of adjacent test point phase current
In formula, c12AFor the relatively electric capacity between test point 1,2, its numerical value very little.
After failure, the difference of adjacent test point faulted phase current
In formula, C12A+CΣ＞ ＞ C12A,Size it is with fault resistance size relevant, generally higher than phase voltage
20%.Therefore Section 2 amplitude is much larger than Section 1, and the amplitude of the difference of faulted phase current and direction are determined by Section 2.
By comparing (1), (2) two formulas, after failure occurs, the difference of the faulted phase current of fault section two ends test point is compared
In before failure generation, amplitude is significantly increased.
2) adjacent test point 1,2 is located at trouble point homonymy.
It is similar with 1) in analysis, it is assumed that test point is respectively positioned on trouble point upstream, has：
Before failure
After failure
After occurring due to earth fault, faulted phase voltage reduction.Compare (3), (4) two formulas to be apparent from, after failure occurs, non-event
Before the difference of the faulted phase current of barrier section two ends test point occurs compared to failure, amplitude reduces.
If test point is respectively positioned on trouble point upstream, after same faulty generation, the failure of non-faulting section two ends test point
The spread value of phase current reduces.
Comprehensive analysis 1), 2), can judge whether section is deposited according to the variation characteristic of the difference of section two ends faulted phase current
In failure.Wherein, the measurement of amplitude size can be provided by calculating the virtual value in the cycle of power frequency one.
If i1A(n)、i2A(n) it is the phase current sampling sequence of adjacent test point.Failure is made to occur the data point subscript at moment
It is zero, defines adjacent test point phase differential current：
ΔiA(n)=i1A(n)-i2A(n) n∈[-N,N-1]
In formula, N=0.02fs, it is a periodic sampling point.When n takes negative integer, before representing that failure occurs；N takes positive integer table
After showing that failure occurs.Before failure occurs, difference between current virtual value is
Define section current break rate
AI=Δ IA,after/ΔIA,before
Analyzed according to upper section, be apparent from the A of non-faulting sectionILess than 1, the A of fault sectionI.More than 1.
The technical solution of the present invention is as follows：
A kind of distribution network line fault Section Location, its feature is, the described method comprises the following steps：
Step S1, determines failure phase and fault moment tf：
After the generation of earth fault is detected, according to phase voltage changing rule, failure phase is selected, is mutated according to phase voltage
Moment or arc-extinction device chugging moment determine fault moment tf；
Step S2, chooses detection means [tf- 0.02s, tf+ 0.02s] it is interval in common 2N point faulted phase current waveform
Data (cycle, i.e., positive and negative 0.02s, totally 2 power frequency periods, i.e., 2N data point before and after failure occurs), calculating current is mutated
Rate AI, formula is as follows：
ΔiA(n)=i1A(n)-i2A(n) n∈[-N,N-1]
In formula, i1A(n)、i2A(n) it is the phase current sampling sequence of adjacent test point, failure occurs under the data point at moment
Zero, N is designated as to count for a periodic sampling；
Step S3, judges whether each section is fault section according to current break rate size, that is, works as AI＞ AIset, it is judged as
Fault section, it is on the contrary then for non-faulting section；
AIsetFor the current break rate threshold value artificially set, the positive number for being 1 or so, it is considered to certain nargin, it can use 1.2~
1.5；
Step 4, the distributing position according to test point on the line, are traveled through, untill finding out fault section successively.
Compared with prior art, the beneficial effects of the invention are as follows：To earth fault, by analyzing faulted phase current in failure
Occur preceding and failure and occur to arc suppression coil the phase current feature before acting, therefrom extract fault characteristic value, and use overall process
Waveform-shaped current mutation rate positioned.Thus, it is only required to which the faulted phase current of measurement circuitry, only considers zero sequence before having broken
The tradition of (needing three phase informations), data acquisition is simple, strong applicability；From the point of view of signal synchronization, total system is using process
Monitoring Data synchronous GPS so that the difference between different test points is sensitiveer.Therefore current generally existing can be solved very well
Single-phase grounded malfunction in grounded system of low current when fault current is faint, poor reliability, low sensitivity the problem of, while will not be right
System introduces interference.
Brief description of the drawings
Fig. 1 is single-phase earthing of small current earthing system schematic diagram
Fig. 2 is distributed fault section positioning system structure figure
Fig. 3 is 10kV system emulation figures
Fig. 4 is the adjacent test point phase differential current waveform of earth fault
Embodiment
The required fault waveform of the present invention comes from distributed fault section alignment system, and system architecture is as shown in Figure 2.Match somebody with somebody
Electric network fault section alignment system is by master station, transformer station's (bus) measurement apparatus and is distributed in the section of distribution line everywhere
Point failure positioner is constituted.Circuit is divided into some sections, each three groups of node installation by fault location node in topology
Measurement apparatus, real-time synchronization collection circuit three-phase current and voltage.
According to the Fault Locating Method of invention, in 10kV power distribution network analogue systems, different types of failure is set.System
Structure chart as shown in figure 3,1., 2., 3. be sector number, failure be arranged on section 2. on.Sample frequency is 20kHz (each cycles
Data point N=400), occurs for failure for 0.7s the moment, and arc-extinction device actuation time is set to 0.04s during earth fault, and electric current is dashed forward
The threshold value of variability is set to 1.2.
The embodiment citing judged for fault section：
Step S1, system starts according to residual voltage after the generation for detecting earth fault, measures A in bus three-phase voltage
Mutually reduce, B, C phase are raised, and are defined as A phase faults；Determine that fault moment is 0.71s according to the phase voltage mutation moment；
Step S2, chooses the faulted phase current Wave data of totally 800 points in each detection means [0,69,0.73] interval
(setting failure to occur to be designated as zero under the data point at moment), according to the definition of current break rate, calculates AI, as a result as shown in table 1, table
1 is singlephase earth fault simulation result；
Wherein, the failure line current variable quantity waveform that hands down is as shown in Figure 4 during 500 Ω grounding resistances.
Step S3, the current break rate of section 2. meets AI>1.2, it is judged as its fault section；Conversely, 1., 3. section is
Non-faulting section.
The singlephase earth fault simulation result of table 1
Claims (2)
1. a kind of distribution network line fault Section Location based on current break rate, it is characterised in that methods described includes
Following steps：
Step S1, determines failure phase and fault moment tf；
Step S2, chooses detection means [tf- 0.02s, tf+ 0.02s] it is interval in common 2N point faulted phase current Wave data,
Calculating current mutation rate AI, formula is as follows：
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ΔiA(n)=i1A(n)-i2A(n) n∈[-N,N-1]
In formula, i1A(n)、i2A(n) it is the phase current sampling sequence of adjacent test point, failure occurs to be designated as under the data point at moment
Zero, N count for a periodic sampling；
Step S3, judges whether each section is fault section according to current break rate size, that is, works as AI＞ AI,set, it is judged as failure
Section, it is on the contrary then for non-faulting section, AIsetFor the current break rate threshold value artificially set, 1.2~1.5 are taken；
Step 4, the distributing position according to test point on the line, are traveled through, untill finding out fault section successively.
2. distribution network line fault Section Location according to claim 1, it is characterised in that the step S1 bags
Include：
System detectio, according to phase voltage changing rule, selects failure phase, when being mutated according to phase voltage to after the generation of earth fault
Carve or the arc-extinction device chugging moment determines fault moment tf。
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| CN105158640B (en) * | 2015-09-15 | 2018-07-20 | 江苏金智科技股份有限公司 | Multi-power supply system and Fault Locating Method based on GPS and current waveform |
| CN105403779B (en) * | 2015-09-29 | 2019-01-04 | 昆明理工大学 | A kind of DC line fault recognition methods based on polar curve current gradient sum |
| CN105914718B (en) * | 2016-04-28 | 2018-04-10 | 长沙理工大学 | A kind of earth-fault protection method based on difference of phase currents |
| CN107290629B (en) * | 2017-07-12 | 2020-09-01 | 国网青海省电力公司海南供电公司 | 10KV low-voltage distribution network ground fault positioning method |
| CN110632462B (en) * | 2019-10-29 | 2022-07-26 | 深圳供电局有限公司 | Small current grounding fault positioning method and system, computer equipment and medium |
| CN110912089B (en) * | 2019-11-26 | 2020-11-06 | 华北电力大学 | Flexible direct-current power distribution system protection method based on local current mutation quantity polarity |
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| CN111596170A (en) * | 2020-05-27 | 2020-08-28 | 国网上海市电力公司 | Fault diagnosis comprehensive positioning method for intelligent distribution network |
| CN112782528B (en) * | 2020-12-31 | 2023-07-18 | 西安理工大学 | Power distribution network fault section positioning method by utilizing PMU |
| CN114089123A (en) * | 2021-12-06 | 2022-02-25 | 国网上海市电力公司 | Fault positioning method, system and storage medium based on phase current time domain characteristics |
| CN116577603B (en) * | 2023-04-27 | 2024-06-04 | 国网山东省电力公司泰安供电公司 | Three-phase current abrupt change-based fault point residual current measuring and calculating method |
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