CN109975653A - A kind of 10 KV distribution circuit fault distance measurements - Google Patents
A kind of 10 KV distribution circuit fault distance measurements Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/02—Measuring effective values, i.e. root-mean-square values
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
Abstract
A kind of 10 KV distribution circuit fault distance measurements, steps are as follows: (1) determining that fault type is line to line fault or three-phase shortcircuit；(2) if three phase short circuit fault, then the phase angle difference of malfunction voltage delay normal operating condition voltage is calculated；(3) if phase fault, then Current Voltage phase angle difference under malfunction is calculated；(4) according to the sample information of fault current, three phase short circuit fault current effective value or two-phase short-circuit fault current effective value are acquired respectively；(5) overall power distribution line information calculates three-phase or the distance between two-phase short-circuit fault point and route beginning.The method of the present invention takes full advantage of distribution line failure information, under conditions of not increasing equipment, can provide more accurate fault localization as a result, improving distribution line O&M efficiency, reduce O&M cost.
Description
Technical field
The present invention relates to a kind of 10 KV distribution circuit fault distance measurements, belong to distribution network technology field.
Background technique
Currently, electric power system fault ranging technology is widely used in 110kV and above route protection, for
10kV distribution line, fault localization and positioning are needed by additionally installation switch, fault detector or other dedicated inspections on route
Device etc. is surveyed, the complexity of route is increased, improves fault localization cost, moreover, these methods are still limited to determine failure
Section more can not accurately provide fault distance, make the lookup of distribution line permanent fault point, it is still necessary to spend a large amount of people
Work is maked an inspection tour, to limit the troubleshooting and fault recovery speed of distribution line.At the same time, distribution line failure information,
It is concerned not enough in O&M practice, the fault signature for itself being included in fault message is made not to be fully utilized.
Summary of the invention
The object of the present invention is to need additionally to pacify by route according to existing 10kV distribution line failure ranging and positioning
Dress switch, fault detector or other special detection devices, increase the complexity of route, improve fault localization cost,
And these methods are still limited to determine fault section, more can not accurately provide fault distance, in view of the above problems, this
Invention proposes a kind of 10 KV distribution circuit fault distance measurements.
The technical solution that the present invention realizes is as follows: a kind of 10 KV distribution circuit fault distance measurements, steps are as follows:
(1) determine that fault type is line to line fault or three-phase shortcircuit；
(2) if three phase short circuit fault, then the phase angle difference of malfunction voltage delay normal operating condition voltage is calculated；
(3) if phase fault, then Current Voltage phase angle difference under malfunction is calculated；
(4) according to the sample information of fault current, three phase short circuit fault current effective value or line to line fault event are acquired respectively
Hinder current effective value；
(5) overall power distribution line information calculates the distance between three phase short circuit fault point and route beginning or line to line fault
The distance between fault point and route beginning.
When the three phase short circuit fault, the phase angle difference σ of malfunction voltage delay normal operating condition voltage are as follows:
Wherein, T is system voltage period, value 0.02s；δ t indicates the phase angle difference corresponding time difference；
δ t=mod (Δ t, T)
In above formula, mod (a, b) is remainder function, and expression parameter a is to parameter b remainder；Electricity when Δ t is normal operating condition
Time difference when corrugating zero crossing and failure are stablized between the zero crossing of voltage waveform；
Δ t=| t2-t1|
In above formula, t1Value at the time of under normal condition by bearing to positive zero crossing；t2For under malfunction by bearing to positive zero passage
Value at the time of point；
t1=tk+1-arcsin(u(tk+1))/100π
t2=tj+1-arcsin(u(tj+1))/100π
Wherein, u (tk+1) be normal operating condition tk+1The voltage sample value at moment, u (tk) and tk+1Previous sampling when
Carve tkThe voltage sample value u (t at momentk) meet following formula:
u(tk) < 0；And u (tk+1)≥0；
u(tj+1) be malfunction tj+1The voltage sample value at moment, the sampled value and previous sampling instant tjMoment
Voltage sample value u (tj) meet following formula:
u(tj) < 0；And u (tj+1)≥0。
The calculation method of the three phase short circuit fault current effective value is as follows:
At the time of determination enters malfunction, to sampled data according to the window real-time perfoming virtual value meter of half period
It calculates, and is constantly compared with the data before the half period, if ratio between the two exceeds limit value, show moment electricity instantly
Stream has been in malfunction；Then into the current sampling data after malfunction to moment, continue according to half period
Window real-time perfoming virtual value calculate, and be constantly compared with the data before the half period, if ratio between the two exists
Within limit value, then show that moment electric current has been in malfunction instantly, calculates current effective value at this time, just obtains three-phase fault
Current effective value；
A phase fault electric current virtual value seeks method:
If sampled value is i when moment tA(t), the virtual value I in the nearest half period of electric currentAtAre as follows:
Wherein, f is current sample frequency, and m is number of samples in system half period, that is, 0.01s, is decided by sample frequency
F, m=f/100；iA(t) be electric current moment t when sampled value, k is count parameter；
The virtual value to clock in the nearest half period at quarter (t-0.01s) is IA(t-0.01), nearest half week with moment t
Virtual value I in phaseAtIt makes comparisons, if meeting: IAt/IA(t-0.01)>=1.5,
Then show that t moment is in malfunction, continues to carry out calculating analysis to the subsequent sampling value of electric current；If after the t moment
By the t of time0At the time of t+t0Virtual value in nearest half periodMeet:
Then take A phase fault electric current virtual value IAKAre as follows:
Similarly, B phase, C phase fault electric current virtual value ask method consistent with A.
The calculation method of the three phase short circuit fault point and the distance between route beginning is as follows:
When distribution line three phase short circuit fault, the phase angle difference σ and phase of malfunction voltage delay normal operating condition voltage
The relationship between parameter is closed, following formula is met:
In formula, R0、X0The resistive component and reactive component of system impedance when occurring for three-phase fault；Rl、XlFor distribution line
Conductor resistance and reactance between fault point and route beginning；RGFor the transition resistance of fault point；σ is malfunction voltage delay
The phase angle difference of normal operating condition voltage；
It is obtained by above formula:
Acquire the ratio between reactance and the resistance of three phase short circuit fault point η are as follows:
When three phase short circuit fault, the distance l at fault point distance route beginningK3Are as follows:
Wherein, IAKA phase fault electric current virtual value when for three phase short circuit fault；UNFor the voltage rating of distribution line；X is lK3
Locate wire type unit length reactance value；B is to be decided by lK3Locate the constant of the line reactance value at wire type beginning, b=X0+
XT；X0The reactive component of system impedance when occurring for failure；XTFor lK3Locate the line reactance value at wire type beginning.
When the phase fault, Current Voltage phase angle difference under malfunctionAre as follows:
In formula, T is system voltage period, value 0.02s；δ τ is the phase angle difference corresponding time difference；
δ τ=mod (Δ τ, T)
In formula, mod (a, b) is remainder function, and expression parameter a is to parameter b remainder；When Δ τ is phase fault state
The time difference of current waveform zero crossing lagging voltage waveform pass zero point；
Δ τ=| τ2-τ1|
In formula, τ1Value at the time of for voltage under phase fault state by bearing to positive zero crossing；τ2For phase fault
Value at the time of electric current is by bearing to positive zero crossing under state；
τ1=τj+1-arcsin(u(τj+1))/100π
τ2=τk+1-arcsin(u(τk+1))/100π
In formula, i (τk+1) it is τ during phase faultk+1The current sampling data at moment, i (τk+1) and τk+1It is previous
Sampling instant τkCurrent sampling data i (the τ at momentk) meet following formula:
i(τk) < 0；And i (τk+1)≥0；
u(τj+1) it is τ during phase faultj+1The voltage sample value at moment, u (τj+1) and τj+1Previous sampling when
Carve τjThe voltage sample value u (τ at momentj) meet following formula:
u(τj) < 0；And u (τj+1)≥0。
The calculation method of the phase fault current effective value is as follows:
At the time of determination enters malfunction, to sampled data according to the window real-time perfoming virtual value meter of half period
It calculates, and is constantly compared with the data before the half period, if ratio between the two exceeds limit value, show moment electricity instantly
Stream has been in malfunction；Then into the current sampling data after malfunction to moment, continue according to half period
Window real-time perfoming virtual value calculate, and be constantly compared with the data before the half period, if ratio between the two exists
Within limit value, then show that moment electric current has been in malfunction instantly, calculates current effective value at this time, just obtains phase-to phase fault
Current effective value；
The algorithm of A phase fault electric current virtual value:
If sampled value is i when moment tA(t), the virtual value I in the nearest half period of electric currentAtAre as follows:
Wherein, f is current sample frequency, and m is number of samples in system half period, that is, 0.01s, is decided by sample frequency
F, m=f/100, iA(t) be electric current moment t when sampled value, k is count parameter；It clocks nearest half week of quarter (t-0.01s)
Virtual value in phase is IA(t-0.01), with the virtual value I in the nearest half period of moment tAtIt makes comparisons, if meeting: IAt/
IA(t-0.01)≥1.5
Then show that t moment is in malfunction, continues to carry out calculating analysis to the subsequent sampling value of electric current, if after the t moment
By the t of time0At the time of t+t0Virtual value in nearest half periodMeet:
Then take A phase fault electric current virtual value IAKFor
Similarly, when phase-to phase fault, the fault current virtual value of another phase asks method consistent with A, under normal circumstances, alternate
Short trouble phase to phase fault current effective value is equal.
The calculation method of the phase fault point and the distance between route beginning is as follows:
When distribution line phase fault, the phase of current waveform zero crossing lagging voltage waveform pass zero point when malfunction
Angular differenceRelationship between relevant parameter, meets following formula:
In formula, R0、X0The resistive component and reactive component of system impedance when occurring for failure；Rl、XlFor distribution line failure
Conductor resistance and reactance between point and route beginning；RGFor the transition resistance of fault point；It is normal for malfunction voltage delay
The phase angle difference of operating status voltage；
It is obtained by above formula:
Acquire the ratio between reactance and the resistance of phase fault point λ are as follows:
When phase fault, fault point and conducting wire beginning distance are lK2Are as follows:
Wherein, IAKA phase fault electric current virtual value when for phase fault；UNFor the voltage rating of distribution line；B is certainly
Due to lK2Locate the constant of the line reactance value at wire type beginning, b=X0+XT；X0The reactance point of system impedance when occurring for failure
Amount；XTFor lK2Locate the line reactance value at wire type beginning；X is the wire type unit length reactance value.
The invention has the advantages that a kind of 10 KV distribution circuit fault distance measurement proposed by the present invention, is to be based on
Distribution line self structure and parameter information judge fault category according to sample information, for three phase short circuit fault, calculate failure
The phase angle difference and fault current size of voltage and normal operating voltage；For phase fault, fault current and failure are calculated
Phase angle difference and fault current size between voltage；Recycle distribution line failure apart from computational algorithm be calculated fault point away from
The distance at offline road beginning can determine failure by means of downstream outage information again at this time since there are branch lines for distribution line
Point accurate location.
Method proposed by the present invention takes full advantage of distribution line failure information, under conditions of not increasing equipment, can mention
For more accurate fault localization as a result, improving distribution line O&M efficiency, O&M cost is reduced.
Detailed description of the invention
Fig. 1 is 10 KV distribution circuit fault distance measurement flow diagrams；
Fig. 2 is distribution line failure current-voltage waveform comparison schematic diagram under normal operating condition and malfunction；
The top of Fig. 2 is current waveform, and lower section is voltage waveform, and Δ t is the normal fortune of malfunction voltage over zero lag
The time difference of row of-state voltage；
The distribution line failure Current Voltage of phase angle difference when Fig. 3 is phase-to phase fault between malfunction current-voltage waveform
Waveform diagram；
The top of Fig. 3 is current waveform, and lower section is voltage waveform, and Δ τ is that current zero-crossing point lags in-phase voltage zero crossing
Time difference.
Specific embodiment
A specific embodiment of the invention is as shown in 10 KV distribution circuit fault distance measurement process of Fig. 1.
The present embodiment 10 KV distribution circuit fault distance measurements of one kind, steps are as follows:
(1) according to the sample information of fault current voltage, determine that fault type is line to line fault or three-phase shortcircuit；
(2) if three phase short circuit fault, then the phase angle difference of malfunction voltage delay normal operating condition voltage is calculated；
(3) if phase fault, then Current Voltage phase angle difference under malfunction is calculated；
(4) according to the sample information of fault current, fault current virtual value is acquired；
(5) overall power distribution line information calculates the distance between short circuit trouble point and route beginning.
1, fault type is determined
Since China's 10kV distribution line is delta connection mode, break down only phase fault and three-phase shortcircuit
Two kinds, wherein phase fault includes internal phase fault and two kinds of strange land phase fault, and strange land phase fault refers to two lines road
Cross-line strange land phase fault at this point, the two lines road that strange land phase fault occurs only has a phase fault electric current, but occurs simultaneously
Phase to phase fault voltage.
Judge that fault type installation following manner carries out:
(1) internal phase fault
If two-phase voltage virtual value is less than 0.9 times of rated value simultaneously, and this biphase current is all larger than 800A, then is determined as
Internal phase fault occurs for route.
Its condition is (by taking AB phase two-phase phase fault as an example):
And
In formula, UA、UBA, B the phase voltage virtual value respectively sampled, calculation formula are respectively as follows:
Wherein, N is number of samples in ac cycle 0.02s, is decided by the sample frequency of device, if sample frequency is f,
N=f/50, uAk、uBkFor voltage transient sampled value, k is count parameter.
IA、IBA, B the phase current virtual value respectively sampled, calculation formula are respectively as follows:
Wherein, N is number of samples in ac cycle 0.02s, is decided by the sample frequency of device, if sample frequency is f,
N=f/50, iAk、iBkFor electric current instantaneous sampling value, k is count parameter.
(2) strange land two-phase short-circuit fault
If two-phase voltage virtual value is less than 0.9 times of rated value simultaneously, and the only phase current in this two-phase is greater than 800A,
Then it is determined as that strange land two-phase short-circuit fault occurs for route.
Its condition is (by taking A differently phase fault as an example):
And
In formula, UA、UBA, B the phase voltage virtual value respectively sampled, calculation formula are respectively as follows:
Wherein, N is number of samples in ac cycle 0.02s, is decided by the sample frequency of device, if sample frequency is f,
N=f/50, uAk、uBkFor voltage transient sampled value, k is count parameter.
IA、IBA, B the phase current virtual value respectively sampled, calculation formula are respectively as follows:
Wherein, N is number of samples in ac cycle 0.02s, is decided by the sample frequency of device, if sample frequency is f,
N=f/50, iAk、iBkFor electric current instantaneous sampling value, k is count parameter.
(3) three phase short circuit fault
If three-phase voltage virtual value is less than 0.9 times of rated value simultaneously, and a three-phase current at least phase current is greater than 800A,
Then it is determined as that three phase short circuit fault occurs for route.Its condition are as follows:
And IA>=800A or IB>=800A or IC≥800A
In formula, UA、UB、UCA, B, C the phase voltage virtual value respectively sampled, calculation formula are respectively as follows:
Wherein, N is number of samples in ac cycle 0.02s, is decided by the sample frequency of device, if sample frequency is f,
N=f/50, uAk、uBk、uCkFor voltage transient sampled value, k is count parameter.
IA、IB、ICA, B, C the phase current virtual value respectively sampled, calculation formula are respectively as follows:
Wherein, N is number of samples in ac cycle 0.02s, is decided by the sample frequency of device, if sample frequency is f,
N=f/50, iAk、iBk、iCkFor electric current instantaneous sampling value, k is count parameter.
(4) other failures
It is unsatisfactory for the failure of above situation, is included in the range of other failures, largely the reason of the generation of other failures simultaneously
Short circuit causes on non-10kV route, and may be that distribution transformer Low-side faults or user's overload cause.For other events
Barrier, then without fault localization.
Method of the invention is only limitted to three kinds of failures described in the kind situation of (1)~(3).
2, the fault distance-finding method of three phase short circuit fault
I, the phase angle difference of malfunction voltage delay normal operating condition voltage is calculated
When alternate or three phase short circuit fault occurs for distribution line, voltage can occur of short duration distortion and be transitioned into stable failure
State, due to distribution line capacity of short circuit for major network capacity very little, distribution line failure is to systematic influence pole
Small, when distribution line failure is in stable condition, voltage waveform is rendered as sine wave.Under normal operating condition and malfunction, voltage
Initial phase angle between waveform is different, shows on waveform, voltage waveform zero crossing and failure are steady when being exactly normal operating condition
Time difference between the zero crossing of timing voltage waveform, not equal to the integral multiple of AC voltage cycle, as shown in Figure 2.The time
The corresponding phase angle of difference is exactly the phase angle difference of malfunction voltage delay normal operating condition voltage.
When distribution line breaks down, the voltage sample value of a period of time and corresponding sampling time before and after record failure,
Data therein are handled.
The data of normal operating condition are judged: if tkThe sampled value at moment meets following formula:
u(tk) < 0；And u (tk+1)≥0；
In formula, u (tk)、u(tk+1) it is respectively tk、tk+1The voltage sample value at moment.
When meeting conditions above, show that voltage is located at t from the zero crossing that negative value becomes positive valuek~tk+1Between moment, at this time
Value t at the time of can be in the hope of under normal condition by bearing to positive zero crossing1Are as follows:
t1=tk+1-arcsin(u(tk+1))/100π
Similarly, the data of malfunction are judged: if tjThe sampled value at moment meets following formula:
u(tj) < 0；And u (tj+1)≥0；
In formula, u (tj)、u(tj+1) it is respectively tj、tj+1The voltage sample value at moment.
When meeting conditions above, show that voltage is located at t from the zero crossing that negative value becomes positive valuej~tj+1Between moment, at this time
Value t at the time of can be in the hope of under malfunction by bearing to positive zero crossing2Are as follows:
t2=tj+1-arcsin(u(tj+1))/100π
Therefore normal operating condition when voltage waveform zero crossing and failure stablize when voltage waveform zero crossing between when
Between poor Δ t are as follows: Δ t=| t2-t1|
Time difference Δ t obtains the corresponding time difference δ t of phase angle difference to system voltage period remainder are as follows:
δ t=mod (Δ t, T)
In formula, mod (a, b) is remainder function, and expression parameter a is the system voltage period to parameter b remainder, T, and value is
0.02s。
To acquire the phase angle difference σ of malfunction voltage delay normal operating condition voltage are as follows:
In formula, T is system voltage period, value 0.02s.
II, the sample information according to fault current, seek fault current virtual value
The present embodiment calculates current value when required fault current virtual value, instead of initiation protective device tripping,
Current effective value under failure stable state, in a complete ac cycle.In order to obtain the value, need to each phase sample rate current
Carry out calculating analysis, it is first determined at the time of entering malfunction, to sampled data according to the window real-time perfoming of half period
Virtual value calculates, and is constantly compared with the data before the half period, if ratio between the two exceeds limit value, shows to work as
Lower moment electric current has been in malfunction.Then to enter malfunction to moment after current sampling data, continue according to
The window real-time perfoming virtual value of half period calculates, and is constantly compared with the data before the half period, if therebetween
Ratio within limit value, then show that moment electric current has been in malfunction instantly, calculates current effective value at this time, just obtains
Three-phase fault current effective value.
Malfunction method of discrimination are as follows: calculate the current information in half period in real time, the constantly calculating some time is engraved in recently
Virtual value in half period, by taking A phase as an example, if sampled value is i when moment tA(t), effective in the nearest half period of electric current
Value IAtAre as follows:
Wherein, f is current sample frequency, and m is number of samples in system half period, that is, 0.01s, is decided by sample frequency
F, m=f/100；iA(t) be electric current moment t when sampled value；K is count parameter.
The virtual value to clock in the nearest half period at quarter (t-0.01s) is IA(t-0.01), nearest half week with moment t
Virtual value I in phaseAtIt makes comparisons, if meeting following formula:
IAt/IA(t-0.01)≥1.5
Then show that t moment is in malfunction, continues to carry out calculating analysis to the subsequent sampling value of electric current, if after the t moment
By the t of time0At the time of t+t0Virtual value in nearest half periodMeet following formula:
Then take A phase fault electric current virtual value IAKAre as follows:
Similarly, B phase, C phase fault electric current virtual value ask method consistent with A.
III, it asks and calculates the distance between three phase short circuit fault point and route beginning
Before and after acquiring failure after the phase angle difference of voltage fundamental and fault current virtual value, can ask calculate route beginning to therefore
The distance between barrier point and conductor resistance component, reactive component and transition resistance size.Ask calculation principle and method as follows.
The present embodiment proposes, when distribution line three phase short circuit fault, malfunction voltage delay normal operating condition voltage
Phase angle difference σ and relevant parameter between relationship, meet following formula:
In formula, R0、X0The resistive component and reactive component of system impedance when occurring for failure；Rl、XlFor distribution line failure
Conductor resistance and reactance between point and route beginning；RGFor the transition resistance of fault point.σ is that malfunction voltage delay is normal
The phase angle difference of operating status voltage.
It can be obtained by formula (3)
Acquire the ratio between reactance and the resistance of three phase short circuit fault point η are as follows:
Meanwhile by taking A phase as an example, Section of 4.2 A phase fault electric current virtual value when having calculated three phase short circuit fault is IAK, therefore
In formula, UNFor the voltage rating of distribution line, i.e. 10.5kV, can be obtained according to formula (4), (5)
There are three unknown number R in formula (6), (7)l、Xl、RG；
Wherein Rl、XlTwo unknown numbers, establishing electric line three phase short circuit fault point and conducting wire beginning distance are lK3, distribution wire
Line conductor itself has impedance, then the conductor resistance R between distribution line failure point and route beginninglAre as follows: Rl=R0+RT+rlK3
In formula, R0The resistive component of system impedance when occurring for failure；RTFor lK3Locate the line resistance at wire type beginning
Value；R is the wire type resistance per unit length value.
Conducting wire reactance X between distribution line failure point and route beginninglAre as follows:
Xl=X0+XT+xlK3
In formula, X0The reactive component of system impedance when occurring for failure；XTFor lK3Locate the line reactance at wire type beginning
Value；X is the wire type unit length reactance value.
By two formulas above it is found that conductor resistance and reactance between distribution line failure point and route beginning are respectively lK3's
Linear function, the two can be denoted as respectively:
Rl=a+rlK3 (8)
Xl=b+xlK3 (9)
In formula, a is to be decided by lK3Locate the constant of the line resistance value at wire type beginning, a=R0+RT；B is to be decided by
lK3Locate the constant of the line reactance value at wire type beginning, b=X0+XT；R, x is respectively lK3Locate wire type resistance per unit length
Value, unit length reactance value.
Based on formula (6)~formula (9), the conductor resistance R between fault point and route beginning can be obtainedl, reactance XlIt is respectively as follows:
The transition resistance R of fault pointGAre as follows:
Finally acquire, when three phase short circuit fault, the distance l at fault point distance route beginningK3Are as follows:
3, the fault distance-finding method of phase fault
I, it asks and calculates Current Voltage phase angle difference under malfunction
When alternate phase short trouble occurs for distribution line, voltage can occur of short duration distortion and be transitioned into stable failure shape
State, due to distribution line capacity of short circuit for major network capacity very little, distribution line failure is minimum to systematic influence,
When distribution line failure is in stable condition, voltage and current waveform is rendered as sine wave.When phase fault, fault current voltage wave
Phase angle difference between shape reflects the size relation between fault point reactance and resistance；Malfunction Current Voltage when phase-to phase fault
Phase angle difference between waveform, shows on waveform, exactly between fault current waveform zero crossing and the zero crossing of voltage waveform
Time difference, not equal to the integral multiple of AC voltage cycle, as shown in Figure 3.The time difference, corresponding phase angle was exactly phase-to phase fault
The phase angle difference of current-voltage waveform under state.
When distribution line breaks down, when recording the current-voltage sampling value and corresponding sampling of phase fault process
Between, data therein are handled.Voltage sample data when phase fault occurs judge: if τjMoment
Sampled value meets following formula:
u(τj) < 0；And u (τj+1)≥0；
In formula, u (τj)、u(τj+1) it is respectively τj、τj+1The voltage sample value at moment.
When meeting conditions above, show that voltage is located at τ from the zero crossing that negative value becomes positive valuej~τj+1Between moment, at this time
Can in the hope of voltage under phase fault state by bearing to positive zero crossing at the time of value τ1Are as follows:
τ1=τj+1-arcsin(u(τj+1))/100π
Current sampling data when phase fault occurs judges: if τkThe sampled value at moment meets:
i(τk) < 0；And i (τk+1)≥0；
In formula, i (τk)、i(τk+1) it is respectively τk、τk+1The current sampling data at moment.
When meeting conditions above, show that voltage is located at τ from the zero crossing that negative value becomes positive valuek~τk+1Between moment, at this time
Can in the hope of electric current under phase fault state by bearing to positive zero crossing at the time of value τ2Are as follows:
τ2=τk+1-arcsin(u(τk+1))/100π
Therefore phase fault state when current waveform zero crossing lagging voltage waveform pass zero point time difference Δ τ are as follows:
Δ τ=| τ2-τ1|
Time difference Δ τ obtains the corresponding time difference δ τ of phase angle difference to system voltage period remainder are as follows:
δ τ=mod (Δ τ, T)
In formula, mod (a, b) is remainder function, and expression parameter a is the system voltage period to parameter b remainder, T, and value is
0.02s。
The phase angle difference of current waveform zero crossing lagging voltage waveform pass zero point when to acquire phase fault state
Are as follows:
In formula, T is system voltage period, value 0.02s.
II, the sample information according to fault current, seek phase-to phase fault current effective value
Phase fault current effective value ask method and three-phase fault current effective value ask method identical, it is first determined into
At the time of entering malfunction, sampled data is calculated according to the window real-time perfoming virtual value of half period, and constantly and half cycle
Data before phase are compared, if ratio between the two exceeds limit value, show that moment electric current has been in failure shape instantly
State.Then into the current sampling data after malfunction to moment, continue the window real-time perfoming according to half period
Virtual value calculates, and is constantly compared with the data before the half period, if ratio between the two shows within limit value
Instantly moment electric current has been in malfunction, calculates current effective value at this time, just obtains phase-to phase fault current effective value.
Malfunction method of discrimination are as follows: calculate the current information in half period in real time, the constantly calculating some time is engraved in recently
Virtual value in half period, by taking A phase as an example, if sampled value is i when moment tA(t), effective in the nearest half period of electric current
Value IAtAre as follows:
Wherein, f is current sample frequency, and m is number of samples in system half period, that is, 0.01s, is decided by sample frequency
F, m=f/100, iA(t) be electric current moment t when sampled value, k is count parameter.
The virtual value to clock in the nearest half period at quarter (t-0.01s) is IA(t-0.01), nearest half week with moment t
Virtual value I in phaseAtIt makes comparisons, if meeting following formula:
IAt/IA(t-0.01)≥1.5
Then show that t moment is in malfunction, continues to carry out calculating analysis to the subsequent sampling value of electric current, if after the t moment
By the t of time0At the time of t+t0Virtual value in nearest half periodMeet following formula:
Then take A phase fault electric current virtual value IAKAre as follows:
Similarly, when phase-to phase fault, the fault current virtual value of another phase asks method consistent with A, under normal circumstances, alternate
Short trouble phase to phase fault current effective value is equal.
III, it asks and calculates the distance between phase fault point and route beginning
The phase angle difference and phase of current waveform zero crossing lagging voltage waveform pass zero point when acquiring phase fault state
Between after short-circuit current virtual value, can ask and calculate route beginning to resistive component, reactive component and the transition between fault point
Resistance sizes.
Ask calculation principle and method as follows:
The present invention proposes, when distribution line phase fault, current waveform zero crossing lagging voltage wave when malfunction
The phase angle difference of shape zero crossingRelationship between relevant parameter, meets following formula:
In formula, R0、X0The resistive component and reactive component of system impedance when occurring for failure；Rl、XlFor distribution line failure
Conductor resistance and reactance between point and route beginning；RGFor the transition resistance of fault point.It is normal for malfunction voltage delay
The phase angle difference of operating status voltage.
It can be obtained by formula (12):
Acquire the ratio between reactance and the resistance of phase fault point λ are as follows:
Simultaneously, it is assumed that AB or AC phase phase fault has occurred, by taking A phase as an example, Section 5.2 when having calculated phase fault
A phase fault electric current virtual value is IAK, therefore,
In formula, UNFor the voltage rating of distribution line, i.e. 10.5kV, can be obtained according to formula (13), (14)
There are three unknown number R in formula (15), (16)l、Xl、RG；
Wherein Rl、XlTwo unknown numbers, establishing electric line phase fault point and conducting wire beginning distance are lK2, distribution wire
Line conductor itself has impedance, then the conductor resistance R between distribution line failure point and route beginninglAre as follows: Rl=R0+RT+rlK2
In formula, R0The resistive component of system impedance when occurring for failure；RTFor lK2Locate the line resistance at wire type beginning
Value；R is the wire type resistance per unit length value.
Conducting wire reactance X between distribution line failure point and route beginninglAre as follows:
Xl=X0+XT+xlK2
In formula, X0The reactive component of system impedance when occurring for failure；XTFor lK2Locate the line reactance at wire type beginning
Value；X is the wire type unit length reactance value.
By two formulas above it is found that conductor resistance and reactance between distribution line failure point and route beginning are respectively lK2's
Linear function, the two can be denoted as respectively:
Rl=a+rlK2 (17)
Xl=b+xlK2 (18)
In formula, a is to be decided by lK2Locate the constant of the line resistance value at wire type beginning, a=R0+RT；B is to be decided by
lK2Locate the constant of the line reactance value at wire type beginning, b=X0+XT；R, x is respectively lK2Locate wire type resistance per unit length
Value, unit length reactance value.
Based on formula (15)~formula (18), the conductor resistance R between fault point and route beginning can be obtainedl, reactance XlIt is respectively as follows:
The transition resistance R of fault pointGAre as follows:
It finally acquires, when phase fault, fault point and conducting wire beginning distance are lK2Are as follows:
Claims (7)
1. a kind of 10 KV distribution circuit fault distance measurements, which is characterized in that the method comprises the following steps:
(1) determine that fault type is line to line fault or three-phase shortcircuit；
(2) if three phase short circuit fault, then the phase angle difference of malfunction voltage delay normal operating condition voltage is calculated；
(3) if phase fault, then Current Voltage phase angle difference under malfunction is calculated；
(4) according to the sample information of fault current, three phase short circuit fault current effective value or two-phase short-circuit fault electricity are acquired respectively
Flow virtual value；
(5) overall power distribution line information calculates three-phase or the distance between two-phase short-circuit fault point and route beginning.
2. a kind of 10 KV distribution circuit fault distance measurement according to claim 1, which is characterized in that the three-phase is short
When the failure of road, the phase angle difference σ of malfunction voltage delay normal operating condition voltage are as follows:
Wherein, T is system voltage period, value 0.02s；δ t indicates the phase angle difference corresponding time difference；
δ t=mod (Δ t, T)
In above formula, mod (a, b) is remainder function, and expression parameter a is to parameter b remainder；Voltage wave when Δ t is normal operating condition
Time difference when shape zero crossing and failure are stablized between the zero crossing of voltage waveform；
Δ t=| t2-t1|
In above formula, t1Value at the time of under normal condition by bearing to positive zero crossing；t2For under malfunction by bearing to positive zero crossing
Moment value；
t1=tk+1-arcsin(u(tk+1))/100π
t2=tj+1-arcsin(u(tj+1))/100π
Wherein, u (tk+1) be normal operating condition tk+1The voltage sample value at moment, u (tk) and tk+1Previous sampling instant tk
The voltage sample value u (t at momentk) meet following formula:
u(tk) < 0；And u (tk+1)≥0；
u(tj+1) be malfunction tj+1The voltage sample value at moment, the sampled value and previous sampling instant tjThe voltage at moment is adopted
Sample value u (tj) meet following formula:
u(tj) < 0；And u (tj+1)≥0。
3. a kind of 10 KV distribution circuit fault distance measurement according to claim 1, which is characterized in that the three-phase is short
The calculation method of road fault current virtual value is as follows:
At the time of determination enters malfunction, sampled data is calculated according to the window real-time perfoming virtual value of half period, and
It is constantly compared with the data before the half period, if ratio between the two exceeds limit value, shows that moment electric current is instantly
In malfunction；Then into the current sampling data after malfunction to moment, continue the window according to half period
Mouth real-time perfoming virtual value calculates, and is constantly compared with the data before the half period, if ratio between the two is in limit value
Within, then show that moment electric current has been in malfunction instantly, calculates current effective value at this time, just obtains three-phase fault electric current
Virtual value；
A phase fault electric current virtual value seeks method:
If sampled value is i when moment tA(t), the virtual value I in the nearest half period of electric currentAtAre as follows:
Wherein, f is current sample frequency, and m is number of samples in system half period, that is, 0.01s, is decided by sample frequency f, m=
f/100；iA(t) be electric current moment t when sampled value, k is count parameter；
The virtual value to clock in the nearest half period at quarter (t-0.01s) is IA(t-0.01), in the nearest half period of moment t
Virtual value IAtIt makes comparisons, if meeting: IAt/IA(t-0.01)>=1.5,
Then show that t moment is in malfunction, continues to carry out calculating analysis to the subsequent sampling value of electric current；If after t moment by
The t of time0At the time of t+t0Virtual value in nearest half periodMeet:
Then take A phase fault electric current virtual value IAKAre as follows:
Similarly, B phase, C phase fault electric current virtual value ask method consistent with A.
4. a kind of 10 KV distribution circuit fault distance measurement according to claim 1, which is characterized in that the three-phase is short
Road fault point and the calculation method at the distance between route beginning are as follows:
When distribution line three phase short circuit fault, the phase angle difference σ of malfunction voltage delay normal operating condition voltage joins to related
Relationship between number, meets following formula:
In formula, R0、X0The resistive component and reactive component of system impedance when occurring for three-phase fault；Rl、XlFor distribution line failure
Conductor resistance and reactance between point and route beginning；RGFor the transition resistance of fault point；σ is that malfunction voltage delay is normal
The phase angle difference of operating status voltage；
It is obtained by above formula:
Acquire the ratio between reactance and the resistance of three phase short circuit fault point η are as follows:
When three phase short circuit fault, the distance l at fault point distance route beginningK3Are as follows:
Wherein, IAKA phase fault electric current virtual value when for three phase short circuit fault；UNFor the voltage rating of distribution line；X is lK3It leads at place
Line style unit length reactance value；B is to be decided by lK3Locate the constant of the line reactance value at wire type beginning, b=X0+XT；X0For
The reactive component of system impedance when failure occurs；XTFor lK3Locate the line reactance value at wire type beginning.
5. a kind of 10 KV distribution circuit fault distance measurement according to claim 1, which is characterized in that described alternate short
When the failure of road, Current Voltage phase angle difference under malfunctionAre as follows:
In formula, T is system voltage period, value 0.02s；δ τ is the phase angle difference corresponding time difference；
δ τ=mod (Δ τ, T)
In formula, mod (a, b) is remainder function, and expression parameter a is to parameter b remainder；Electric current when Δ τ is phase fault state
The time difference of waveform pass zero point lagging voltage waveform pass zero point；
Δ τ=| τ2-τ1|
In formula, τ1Value at the time of for voltage under phase fault state by bearing to positive zero crossing；τ2For phase fault state
Value at the time of lower electric current is by bearing to positive zero crossing；
τ1=τj+1-arcsin(u(τj+1))/100π
τ2=τk+1-arcsin(u(τk+1))/100π
In formula, i (τk+1) it is τ during phase faultk+1The current sampling data at moment, i (τk+1) and τk+1Previous sampling
Time instant τkCurrent sampling data i (the τ at momentk) meet following formula:
i(τk) < 0；And i (τk+1)≥0；
u(τj+1) it is τ during phase faultj+1The voltage sample value at moment, u (τj+1) and τj+1Previous sampling instant τj
The voltage sample value u (τ at momentj) meet following formula:
u(τj) < 0；And u (τj+1)≥0。
6. a kind of 10 KV distribution circuit fault distance measurement according to claim 1, which is characterized in that described alternate short
The calculation method of road fault current virtual value is as follows:
At the time of determination enters malfunction, sampled data is calculated according to the window real-time perfoming virtual value of half period, and
It is constantly compared with the data before the half period, if ratio between the two exceeds limit value, shows that moment electric current is instantly
In malfunction；Then into the current sampling data after malfunction to moment, continue the window according to half period
Mouth real-time perfoming virtual value calculates, and is constantly compared with the data before the half period, if ratio between the two is in limit value
Within, then show that moment electric current has been in malfunction instantly, calculates current effective value at this time, just obtains phase-to phase fault electric current
Virtual value；
The algorithm of A phase fault electric current virtual value:
If sampled value is i when moment tA(t), the virtual value I in the nearest half period of electric currentAtAre as follows:
Wherein, f is current sample frequency, and m is number of samples in system half period, that is, 0.01s, is decided by sample frequency f, m=
F/100, iA(t) be electric current moment t when sampled value, k is count parameter；It clocks in the nearest half period at quarter (t-0.01s)
Virtual value is IA(t-0.01), with the virtual value I in the nearest half period of moment tAtIt makes comparisons, if meeting: IAt/IA(t-0.01)≥
1.5
Then show that t moment is in malfunction, continue to carry out calculating analysis to the subsequent sampling value of electric current, if after t moment by
The t of time0At the time of t+t0Virtual value in nearest half periodMeet:
Then take A phase fault electric current virtual value IAKFor
Similarly, when phase-to phase fault, the fault current virtual value of another phase asks method consistent with A, under normal circumstances, phase fault
Failure phase to phase fault current effective value is equal.
7. a kind of 10 KV distribution circuit fault distance measurement according to claim 1, which is characterized in that described alternate short
Road fault point and the calculation method at the distance between route beginning are as follows:
When distribution line phase fault, the phase angle difference of current waveform zero crossing lagging voltage waveform pass zero point when malfunctionRelationship between relevant parameter, meets following formula:
In formula, R0、X0The resistive component and reactive component of system impedance when occurring for failure；Rl、XlFor distribution line failure point with
Conductor resistance and reactance between route beginning；RGFor the transition resistance of fault point；For malfunction voltage delay normal operation
The phase angle difference of of-state voltage；
It is obtained by above formula:
Acquire the ratio between reactance and the resistance of phase fault point λ are as follows:
When phase fault, fault point and conducting wire beginning distance are lK2Are as follows:
Wherein, IAKA phase fault electric current virtual value when for phase fault；UNFor the voltage rating of distribution line；B is to be decided by
lK2Locate the constant of the line reactance value at wire type beginning, b=X0+XT；X0The reactive component of system impedance when occurring for failure；
XTFor lK2Locate the line reactance value at wire type beginning；X is the wire type unit length reactance value.
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| CN110456219A (en) * | 2019-08-12 | 2019-11-15 | 国网江西省电力有限公司电力科学研究院 | A kind of appraisal procedure of distribution line short voltage dip degree |
| CN112748366A (en) * | 2021-02-07 | 2021-05-04 | 石家庄科林电气股份有限公司 | Method for judging short-circuit fault of transient recording type fault indicator |
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| CN116613716A (en) * | 2023-07-20 | 2023-08-18 | 国网江西省电力有限公司电力科学研究院 | Voltage sag control method and system based on fault domain |
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| CN116613716A (en) * | 2023-07-20 | 2023-08-18 | 国网江西省电力有限公司电力科学研究院 | Voltage sag control method and system based on fault domain |
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