CN110244192A - A kind of power overhead network earth fault distance measurement method - Google Patents
A kind of power overhead network earth fault distance measurement method Download PDFInfo
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- CN110244192A CN110244192A CN201910677475.7A CN201910677475A CN110244192A CN 110244192 A CN110244192 A CN 110244192A CN 201910677475 A CN201910677475 A CN 201910677475A CN 110244192 A CN110244192 A CN 110244192A
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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
The invention discloses a kind of power overhead network earth fault distance measurement methods; belong to the field of relay protection in power engineering; the following steps are included: a, the failure phase of earth fault line and the head end of any non-faulting phase be shorted by sample circuit; it forms head end and is shorted point A, failure phase and the end of above-mentioned non-faulting phase are shorted；B, it is shorted between point A and the earth earthed system in head end and injects high pressure low frequency ac source signal, and acquire sample circuit electric parameter；C, then the parameter for changing sample circuit re-injects high pressure low frequency ac source signal, and acquire sample circuit electric parameter；D, the resistance that equation group calculates the forward and backward transmission line of electricity of earth fault is listed using the electric parameter acquired in b, c, and calculates the position of fault point according to the overall length of transmission line of electricity.
Description
Technical field
The present invention relates to fault localization technical field in electric system, specially a kind of power overhead network earth fault distance measurement
Method.
Background technique
Neutral non-effective grounding mode, also known as small current neutral grounding system is widely used in China's 6kV~35kV power distribution network,
Advantage is when singlephase earth fault occurs, not need to turn off fault loop, allow to operate with failure one to two hours.It lacks
Point is can not to confirm which circuit is problem go out on when singlephase earth fault occurs, and can not quickly find fault point.Due to
Phase voltage caused by this failure, which is increased, constitutes very big threat to the insulation performance of system, it is necessary to find fault loop rapidly and add
To exclude.Although having had the line selection apparatus and pointing device of comparative maturity in the market, positioning operation needs to return failure
Road segmentation, pole-climbing mount detection sensor, and operating process is relative complex, position determination of fault low efficiency.Since distribution network is in the presence of more
Grade branch, and a large amount of distribution transformers are installed on circuit, so as to cause electric-resistivity method, the traveling wave method for being widely used in transmitting loop
Etc. technology be difficult to apply on distribution loop.So designing a kind of overhead line earth fault distance measurement method becomes a kind of urgent
Demand.
Summary of the invention
The technical problem to be solved by the present invention is providing a kind of a kind of electricity of quick obtaining overhead transmission line grounding point position
Power overhead line earth fault distance measurement method.
The technical solution of the technical problem to be solved in the present invention is:
A, the head end of the failure phase that earth fault line occurs and any non-faulting phase in the faulty line is passed through and is adopted
Sample circuit is shorted, and the sample circuit includes the first, second sampling resistor being connected in series, first, second sampling
The tie point of resistance is formed as head end and is shorted point A, will occur the failure phase of earth fault line with it is above-mentioned in the faulty line
The end of non-faulting phase is shorted, and is formed as end and is shorted point B, the failure phase after short circuit mutually constitutes fault localization with non-faulting
Circuit；
B, injection high pressure low frequency ac source signal to fault localization between point A and the earth earthed system is shorted in head end to return
Road, and acquire the electrical quantity parameter in fault localization circuit and the electric parameter of high pressure low frequency ac source signal；
C, change the resistance value of the first and second sampling resistor, be shorted between point A and the earth earthed system in head end inject height again
Frequency ac supply signal is forced down to fault localization circuit, and acquires the electrical quantity parameter in fault localization circuit and high pressure low frequency is handed over
The electric parameter of galvanic electricity source signal；
D, forward and backward defeated of earth fault is calculated using electric parameter collected in step b, c and according to impedance method
The resistance of electric line, and fault point distance injection high pressure low frequency ac source signal one end is calculated according to the overall length of transmission line of electricity
Length.
Preferably, the maximum output voltage of the signal source is the 80%~110% of open-wire loop voltage rating.
Preferably, the maximum output voltage of the signal source is the 85%~100% of open-wire loop voltage rating.
Preferably, the frequency of the signal source is 0.5~15Hz.
Preferably, the frequency of the signal source is 1~5Hz.
Preferably, the resistance of the earth fault of the ground fault phase to head end short circuit point A are leading portion resistance, described to connect
The earth fault of earth fault phase is shorted the resistance of point B to end as back segment resistance.
The step b is operated as follows: the voltage value and high pressure low-frequency ac power letter of the first, second sampling resistor of measurement
Number voltage value, and list according to Ohm's law and Kirchhoff's second law first equation in fault localization circuit；
The step c is operated as follows: the resistance value of the first sampling resistor of adjustment and/or the second sampling resistor, so that after adjustment
The first sampling resistor and/or the second sampling resistor resistance value be different from adjustment before resistance value,
Later, the voltage value of the first and second sampling resistor and the voltage value of high pressure low frequency ac source signal, and root are measured
Second equation in fault localization circuit is listed according to Ohm's law and Kirchhoff's second law；
The step d is operated as follows: solving leading portion resistance with after according to the linear equation in two unknowns group that the first and second equation forms
Section resistance resistance value, according to the overall length of the resistance value of the conducting wire principle directly proportional to length and transmission line of electricity calculate fault point away from
Length from injection high pressure low frequency ac source signal one end, first, second sampling resistor are precision resistance.
Preferably, in step b, when measurement records the voltage value of the first, second sampling resistor, the first sampling resistor and failure
It is connected.In step c, when measurement records, the second sampling resistor is connected with failure.
Preferably, the first sampling resistor and/or the second sampling resistor there are two sample circuit is set, in two sample circuits
Resistance value it is different,
In step b, it is shorted when measurement records using first sample circuit；
In step c, it is shorted when measurement records using second sample circuit.
Preferably, in step b and step c: also acquisition sample circuit and failure phase tie point and head end be shorted point A it
Between voltage, and collection sample circuit and non-faulting phase tie point and head end be shorted point A between voltage, to avoid contact with
The influence of resistance.
The invention has the benefit that quickly fault point general location, shortening loop fault the time can be searched,
Improve power supply quality.
Detailed description of the invention
Fig. 1 is the schematic diagram of the embodiment of the present invention one,
Fig. 2 is equivalent circuit diagram when measuring for the first time in the embodiment of the present invention one,
Fig. 3 is equivalent circuit diagram when measuring again in the embodiment of the present invention one,
Fig. 4 is the schematic diagram of two kinds of collection voltages of the embodiment of the present invention.
In figure:
Rkb, back segment resistance；Rak, leading portion resistance；R02, the second sampling resistor；R01, the first sampling resistor；
Specific embodiment
To keep technical solution of the present invention and beneficial effect clearer, embodiments of the present invention are done further below
Explain in detail.
Embodiment one:
When ground fault occurs in overhead line, microcomputer protective relay device in the prior art, which can be determined that be out of order, is mutually
A, which phase in B, C three-phase, but can not positioning both ground fault point position or general position, this method is based on known
Earth fault line failure phase and non-faulting phase, calculated using impedance method, and then earth fault is calculated
Position.
A kind of overhead line earth fault distance measurement method disclosed by the invention, comprising the following steps:
A, the head end of the failure phase that earth fault line occurs and any non-faulting phase in the faulty line is passed through and is adopted
Sample circuit is shorted.Wherein sample circuit is first, second sampling resistor R01, R02 being connected in series.First, second sampling
The tie point of resistance R01, R02 are formed as head end and are shorted point A.
Since sensed current signal needs current sensor or current transformer that instrument is recycled to be detected, surveying
It measures relatively complicated when electric current.And it is more direct to detect voltage, directly utilizes protective relaying device or intelligence instrument
With measurement, therefore for the ease of measuring and operating, the acquisition of electric parameter, electricity herein are realized by the way of collection voltages
Gas parameter refers to the parameters such as voltage, electric current, phase angle.Pass through the first, second sampling resistor of acquisition when measuring
The voltage of the high pressure low frequency ac source signal of voltage and the signal source output at the both ends of R01, R02, and then derive and calculate
Flow through the electric current of first, second sampling resistor R01, R02.
Assuming that the head end of overhead transmission line is located at first substation or distribution substation, tail end is located at second substation or tail end is located at use
Family load ground.Assume that ground fault occurs in k point simultaneously and ground fault is mutually C phase.If substation is detected in first,
It is shorted non-faulting phase A phase, the failure phase C phase of the faulty line of first substation.It is shorted non-faulting phase B phase and failure phase C phase is same
It can measure, in the present embodiment for being shorted non-faulting phase A phase, failure phase C phase.First substation is head end, second substation
As end.The resistance of the earth fault k of ground fault phase to head end is leading portion resistance Rak, the ground connection event of ground fault phase
The resistance of barrier point to end is back segment resistance Rkb.Before the earth fault k of ground fault phase is to the impedance that head end is shorted point A
Section impedanceThe earth fault of ground fault phase is shorted the impedance of point B to end as back segment impedance
The end of the failure phase that earth fault line occurs and the above-mentioned non-faulting phase in the faulty line is shorted,
Be formed as end and be shorted point B.It is based on above-mentioned steps it is assumed that end be shorted point B Ji Yi substation, be shorted failure phase C phase with
Non-faulting phase A phase.Or in order to simplify operation, maloperation is reduced, the faulty line of second substation equally can be directly shorted
A, B, C three-phase.
Failure phase after short circuit forms fault localization circuit with non-faulting phase and sample circuit.Due to the two of A, C two-phase
End has been shorted, therefore fault localization circuit is an annular circuit.
B, injection high pressure low frequency ac source signal to fault localization between point A and the earth earthed system is shorted in head end to return
Road.Acquire the electrical quantity parameter in fault localization circuit and the electric parameter of high pressure low frequency ac source signal.
In a power distribution system, grounded screen or earthed system are necessary electric utilities.The grounding point of faulty line is suitable
In wherein being connect fault localization circuit greatly with grounded screen.And it is again provided with earthed system in first substation, because
This by grounded screen perhaps greatly as virtual wires be connected to fault localization circuit grounding point first substation grounded screen or
The leading point of earthed system can be used as a signal input node in fault localization circuit.The head end in fault localization circuit is shorted
The node that point A is inputted as another signal in fault localization circuit.Then it is loaded between the node of the two signals input
On one high pressure low frequency ac source signal to fault localization circuit.
The voltage of high pressure low frequency ac source signal is the 80%~110% of overhead transmission line voltage rating, the frequency of signal source
Rate is 0.5~15Hz.Preferably, the voltage of high pressure low frequency ac source signal be overhead transmission line voltage rating 85%~
100%, the frequency of signal source is 1~5Hz.Use voltage for the voltage rating of overhead transmission line, frequency 1Hz in the present embodiment.
The voltage of high pressure low frequency ac source signal does not destroy existing overhead transmission line to reach breakdown grounding point simultaneously
Subject to the insulating requirements on road, therefore use the 85%~100% of overhead transmission line voltage rating.
In the prior art, those skilled in the art think, due to mounting transformer and line conductor pair on overhead transmission line
The influence of ground capacitor either uses DC signal source or alternating message source, all using impedance method measurement ground fault position
With biggish error.The innovation of the invention consists in that overcoming managing the routine of overhead transmission line ranging for those skilled in the art
Solution and technology prejudice can use impedance method and obtain fault point using low-frequency ac power signal loading into faulty line
Position.By our company developer research and practice discovery, using high pressure low frequency ac signal loading to failure phase with
When between non-faulting phase and the earth, signal injection mode be two phase lines over the ground between inject, at this time:
One, transformer primary side induction reactance Zl=2 π fL, frequency is higher, inductance is bigger, and induction reactance value is bigger, when induction reactance value much
When greater than impedance loop, it is equivalent to open circuit, when frequency is 0, is direct current, is equivalent to short circuit.In the prior art, the electricity of transformer
Sense often reaches hundred prosperous grades, even if frequency is very low, induction reactance value is also to be far longer than overhead transmission line in the range of hundreds of henries
Resistance, it can be considered that being open-circuit condition.In actual operation, due to the power transmission line of route itself material and environment
It influences, the pressure difference very little between two phase lines, simultaneously as the electric current of injection is in 100mA hereinafter, the maximum resistance of cable is less than
10 Ω, therefore the voltage difference between two phase lines of load high pressure low frequency ac source signal is 1V or is less than 1V.The pressure of 1V
The electric current very little that difference generates transformer and transformer load, can be ignored, therefore avoid transformer and its load
Influence to ranging.And when using direct current, transformer is equivalent to short circuit, equally influence measurement result, therefore direct current is unavailable, i.e.,
0Hz is unavailable.Two, what overhead transmission line distribution capacity generated after loading AC signal be to earth-current it is unavoidable,
The wherein total capacitive reactance Zc=1/ in circuit (2 π fC), higher in frequency, the capacity current generated is bigger, influences measurement result.Cause
The lower signal source of this selected frequency, keeps its capacitive reactance higher, reduces influence of the capacity current to measurement result.In practical application
In the process, using low frequency ac source signal, the influence for mounting transformer on the line can be ignored, but direct-to-ground capacitance
Influence can not be eliminated, influence of the capacity current of diminution direct-to-ground capacitance that can only be unlimited to current in resistance property.In order to make to calculate more
Accurately, it is calculated during calculating using phasor approach.Or each voltage of acquisition is isolated into appearance by orthogonal operations
Property electric current and capacitive voltage, then calculated and handled using current in resistance property, also need to acquire signal source voltage letter based on this
Number.
Comprehensive first and Article 2, when using low-frequency ac signal, the total capacitive reactance of route is larger, and capacity current is smaller, right
Current in resistance property influence is smaller, can isolate resistive composition by phasor calculation.The inductance of the prosperous rank of transformer hundred is suitable simultaneously
It therefore can be measured and calculated using low frequency ac source signal and using impedance method in open circuit.By company's comprehensively measuring and calculating
Frequency range selects between 1Hz~5Hz.In order to reappear ground fault, make earth fault in load high pressure low-frequency ac telecommunications
It is grounded again in the state of number, output voltage is the 80%~100% of overhead transmission line voltage rating.Wherein preferred output voltage is
The voltage rating of overhead transmission line.
C, change the resistance value of first and second sampling resistor R01, R02, again head end be shorted point A and the earth earthed system it
Between injection high pressure low frequency ac source signal to fault localization circuit, and acquire the electrical quantity parameter and height in fault localization circuit
Force down the electric parameter of frequency ac supply signal.
It includes following several for wherein adjusting the resistance value mode of the first and second sampling resistor:
(1), when measuring for the first time, as shown in Fig. 2, the first and second sampling resistor resistance value is different, the first sampling resistor R01 and
Non-faulting is connected, and the second sampling resistor R02 is connected with failure.
Second when measuring, as shown in figure 3, the first sampling resistor R01 is connected with failure, the second sampling resistor R02 and
Non-faulting is connected.
Finally, collection voltages parameter lists the resistance value that equation group solves leading portion resistance Rak and back segment resistance Rkb.And then
Calculate the distance that grounding point is shorted point A and end short circuit point B apart from head end.
(2), the sampling electricity of the first sampling resistor R01 and/or second there are two sample circuit is set, in two sample circuits
The resistance value for hindering R02 is different, is shorted when measurement record using first sample circuit for the first time；The is utilized when second measurement record
Two sample circuits are shorted.
D, forward and backward defeated of earth fault is calculated using electric parameter collected in step b, c and according to impedance method
The resistance of electric line, and fault point distance injection high pressure low frequency ac source signal one end is calculated according to the overall length of transmission line of electricity
Length.
Taking the first method as an example, for step b, c, d, specifically:
Since leading portion resistance Rak, back segment resistance Rkb are two unknown numbers, at least need two set of equations at equation group,
The electrical quantity parameter in the fault localization circuit for therefore needing to acquire two states is calculated.In the present embodiment, utilization is non-equilibrium
The principle of electric bridge obtains the resistance value of leading portion resistance Rak, back segment resistance Rkb.
Step b operation is as follows:
Measure the voltage value of first, second sampling resistor R01, R02 and the high pressure low-frequency ac power of signal source output
Signal voltage value.The resistance value of first and second sampling resistor R01, R02 is respectively R at this time11、R12.As shown in Fig. 2, the first sampling electricity
Resistance R01 is connected with non-faulting, and the second sampling resistor R02 is connected with failure.According to voltage waveformWhereinFor first phase.FunctionFor periodic function.The first phase of the output voltage in definition signal source is 0 degree in the present embodiment,
After being converted to phasorUsing the voltage of signal source output as benchmark signal, by the way that collected first and second is sampled
The voltage in the voltage and signal source of resistance R01, R02 is compared to obtain the phasor value of the voltage of the first sampling resistor R01 The phasor value of the voltage of second sampling resistor R02Direct-to-ground capacitance is equivalent to capacitive reactance, therefore fault localization
Circuit is a kind of capacitive load as load, therefore can generate an angle.And according to Ohm's law and Kirchhoff's second law
List first equation in fault localization circuit.It can according to the resistance value of the voltage value of acquisition and first and second sampling resistor R01, R02
To calculate the electric current for flowing through the first and second resistance place circuit.
First can be obtained according to the angle of the voltage U12 of the first sampling resistor and the voltage of signal source, and by orthogonal calculation
The resistive component of the voltage of sampling resistor.
As shown in Fig. 2, the current in resistance property for flowing through non-faulting phase is
I11=U11cosα1/R11 (1)
Flow through the electric current of failure phase
I12=U12cosβ1/R12 (2)
Leading portion resistance Rak, back segment resistance Rkb can must be flowed through by being multiplied by electric current with leading portion resistance Rak, back segment resistance Rkb
Voltage, according to Kirchhoff's second law: in any one closed circuit, the algebraical sum of the voltage drop on each element is zero
Principle can list equation,
U11cosα1+I11(Rak+2Rkb)=U12cosβ1+I12Rak (3)
It brings formula (1) into and formula (2) obtains,
U11cosα1+(U11cosα1/R11)(Rak+2Rkb)=U12cosβ1+(U12cosβ1/R12)Rak (4)
Step c, the resistance value for adjusting the first sampling resistor R01 and/or the second sampling resistor R02, so that adjusted first
The resistance value of sampling resistor R01 and the second sampling resistor R02 are different from the resistance value before adjustment.The company of sample circuit is exchanged in capital and interest
For connecing mode, the first sampling resistor R01 is connected with failure, and the second sampling resistor R02 is connected with non-faulting.Due to needing
The parameter for changing fault measuring circuit could list different equatioies again, therefore make above-mentioned adjustment.
The voltage value of first and second sampling resistor R01, R02 is measured, and is arranged according to Ohm's law and Kirchhoff's second law
Be out of order second equation in ranging circuit.The first phase of the output voltage of the signal source of acquisition is equally set as 0 degree, is converted to phasor
Afterwards 20=U20∠0°.The phasor value of the voltage of first and second sampling resistor R01, R02 is
As shown in figure 3, flowing through the electric current of non-faulting phase
I22=U22cosβ2/R12 (5)
The electric current of failure phase is flowed through,
I21=U21cosα2/R11 (6)
It is as follows to list equation,
U21cosα2+I21Rak=U22cosβ2+I22(Rak+2Rkb) (7)
Formula (5) and formula (6) is brought into formula (7) to obtain,
U21cosα2+(U21cosα2/R11)Rak=U22cosβ2+(U22cosβ2/R12)(Rak+2Rkb) (8)
Step d, according to the electric parameter acquired in step b and step c, equation i.e. formula (4) and formula (8) are listed.Root
The resistance value of leading portion resistance Rak and back segment resistance Rkb are solved according to the linear equation in two unknowns group that formula (4) and formula (8) form.Due to
The length of conducting wire and the resistance value of conducting wire are directly proportional, thus can calculate fault point distance monitoring circuit both ends distance account for it is aerial
The ratio of total line length.Earth fault distance injection low frequency is calculated according to ratio and according to the known length of overhead transmission line
The length of ac supply signal one end.
It for ease of calculation and measures, while in order to obtain higher computational accuracy, wherein the first, second sampling resistor
R01, R02 are precision resistance.
It can equally be calculated using phasor approach, wherein the line impedance of the earth fault of ground fault phase to head end
The reactance value of leading portion impedance Xak is assumed to beThe line impedance of the earth fault of ground fault phase to end is back segment impedance
The impedance value of Xkb is assumed to beIt is calculated using the above-mentioned principle to establish an equationWithAfter resistance value, reactance is being isolated's
The resistance of real part, i.e. route is
Embodiment two
Based on embodiment one in step c:
Also acquire that sample circuit and failure are connected contact and head end is shorted voltage between point A and sample circuit and non-
Failure tie point and head end are shorted the voltage between point A, with the contact resistance to avoid sample circuit and the tie point of failure phase
And sample circuit is connected influence of the partial pressure to measurement result that the contact resistance of contact generates with non-faulting.
As shown in figure 4, when measuring first time, the phasor value of the voltage of the signal source output of acquisition is
The phasor value of the voltage of collected first and second sampling resistor R01, R02First sampling resistor R01 and non-faulting phase
The phasor value of voltage that contact and head end are shorted between point A of being connected isSecond sampling resistor R02 and failure be connected contact with
Head end be shorted point A between voltage beWhereinIts
In the first sampling resistor R01 resistance value be R11, the resistance value of the second sampling resistor R02 is R12, the equation listed are as follows:
U13cosδ1+(U11cosα1/R11)(Rak+2Rkb)=U14cosε1+(U12cosβ1/R12)Rak (9)
The resistance value for adjusting the first sampling resistor R01 is R21, the resistance value of the second sampling resistor R02 is constant, collected at this time
The phasor value of the voltage of first and second sampling resistor R01, R02First sampling resistor R01 is connected contact with non-faulting
The phasor value of voltage being shorted between point A head end isSecond sampling resistor R02 and the connected contact of failure and head end are shorted
Voltage between point A isWhereinList equation
Formula:
U23cosδ2+(U21cosα2/R21)(Rak+2Rkb)=U24cosε2+(U22cosβ2/R12)Rak (10)
Equation group is formed by above-mentioned (9), (10) two equations and solves the resistance of leading portion resistance Rak and back segment resistance Rkb
Value.Then it is calculated using the resistance value solved.It is possible to prevente effectively from influence of the contact resistance to voltage acquisition in the embodiment,
Improve operational precision.
In conclusion only presently preferred embodiments of the present invention, is not supposed to be a limitation to the present invention, by above-mentioned
Description, relevant staff completely can without departing from the scope of the technological thought of the present invention', carry out multiplicity change
More and modify.Technical scope of the invention is not limited to the contents of the specification, all claimed range institutes under this invention
The shape stated, construction, feature and the so-called equivalent changes and modifications of spirit should all include and scope of the presently claimed invention
It is interior.
Claims (9)
1. a kind of power overhead network earth fault distance measurement method, it is characterised in that:
A, the head end of failure phase and any non-faulting phase in the faulty line that earth fault line occurs is passed through into sampling electricity
Road is shorted, and the sample circuit includes the first, second sampling resistor (R01, R02) being connected in series,
The tie point of first, second sampling resistor (R01, R02) is formed as head end and is shorted point A,
The end of the failure phase that earth fault line occurs and the above-mentioned non-faulting phase in the faulty line is shorted, is formed
It is shorted point B for end,
Failure phase after short circuit mutually constitutes fault localization circuit with non-faulting；
B, it is shorted between point A and the earth earthed system in head end and injects high pressure low frequency ac source signal to fault localization circuit,
And acquire the electrical quantity parameter in fault localization circuit and the electric parameter of high pressure low frequency ac source signal；
C, change the resistance value of the first and second sampling resistor (R01, R02), be shorted between point A and the earth earthed system in head end again
High pressure low frequency ac source signal is injected to fault localization circuit, and acquires the electrical quantity parameter and high pressure in fault localization circuit
The electric parameter of low frequency ac source signal；
D, the forward and backward power transmission line of earth fault is calculated using electric parameter collected in step b, c and according to impedance method
The resistance on road, and the length that fault point distance injects high pressure low frequency ac source signal one end is calculated according to the overall length of transmission line of electricity
Degree.
2. a kind of power overhead network earth fault distance measurement method according to claim 1, it is characterised in that:
The maximum output voltage of the signal source is the 80%~110% of open-wire loop voltage rating.
3. a kind of power overhead network earth fault distance measurement method according to claim 2, it is characterised in that:
The maximum output voltage of the signal source is the 85%~100% of open-wire loop voltage rating.
4. a kind of power overhead network earth fault distance measurement method according to claim 1, it is characterised in that:
The frequency of the signal source is 0.5~15Hz.
5. a kind of power overhead network earth fault distance measurement method according to claim 4, it is characterised in that:
The frequency of the signal source is 1~5Hz.
6. a kind of power overhead network earth fault distance measurement method according to claim 1 or 2 or 4, it is characterised in that:
The resistance of the earth fault of the ground fault phase to head end short circuit point A are leading portion resistance (Rak),
The earth fault of the ground fault phase to end be shorted point B resistance be back segment resistance (Rkb),
The step b is operated as follows: the voltage value and high pressure low-frequency ac of measurement the first, second sampling resistor (R01, R02)
The voltage value of power supply signal, and list according to Ohm's law and Kirchhoff's second law first equation in fault localization circuit；
The step c is operated as follows: the resistance value of adjustment the first sampling resistor (R01) and/or the second sampling resistor (R02), so that
The resistance value of first sampling resistor (R01) adjusted and/or the second sampling resistor (R02) is different from the resistance value before adjustment,
Later, the voltage value of the first and second sampling resistor (R01, R02) and the voltage of high pressure low frequency ac source signal are measured
It is worth, and lists second equation in fault localization circuit according to Ohm's law and Kirchhoff's second law；
The step d is operated as follows: according to the first and second equation form linear equation in two unknowns group solve leading portion resistance (Rak) and
The resistance value of back segment resistance (Rkb) is calculated according to the overall length of the resistance value of the conducting wire principle directly proportional to length and transmission line of electricity
Fault point distance injects the length of high pressure low frequency ac source signal one end,
First, second sampling resistor (R01, R02) is precision resistance.
7. a kind of power overhead network earth fault distance measurement method according to claim 6, it is characterised in that:
In step b, measurement record the first, second sampling resistor (R01, R02) voltage value when, the first sampling resistor (R01) and
Failure is connected,
In step c, when measurement records, the second sampling resistor (R02) is connected with failure.
8. a kind of power overhead network earth fault distance measurement method according to claim 6, it is characterised in that:
The first sampling resistor (R01) and/or the second sampling resistor (R02) there are two sample circuit is set, in two sample circuits
Resistance value it is different,
In step b, it is shorted when measurement records using first sample circuit；
In step c, it is shorted when measurement records using second sample circuit.
9. a kind of power overhead network earth fault distance measurement method according to claim 6, it is characterised in that:
In step b and step c: also acquisition sample circuit and the tie point and head end of failure phase are shorted the voltage between point A, with
And collection sample circuit and the tie point and head end of non-faulting phase are shorted the voltage between point A, to avoid contact with the influence of resistance.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910677475.7A CN110244192B (en) | 2019-07-25 | 2019-07-25 | Electric power overhead line ground fault distance measurement method |
Applications Claiming Priority (1)
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