CN108919051B - Power line fault point positioning method - Google Patents

Power line fault point positioning method Download PDF

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CN108919051B
CN108919051B CN201810639317.8A CN201810639317A CN108919051B CN 108919051 B CN108919051 B CN 108919051B CN 201810639317 A CN201810639317 A CN 201810639317A CN 108919051 B CN108919051 B CN 108919051B
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杜富豪
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Wuhan Tuoqing Technology Co ltd
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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
    • 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
    • G01R31/088—Aspects of digital computing

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Abstract

A power line fault point locating method for calculating the location of a fault point of a three-phase power line, comprising the steps of: acquiring positive sequence current i of measuring point M on line1MZero sequence current i0MAnd a positive sequence current i at another measuring point N on the line1NZero sequence ofCurrent i0N(ii) a Measuring basic data of the three-phase power line, including positive sequence resistance r1Inductance l per unit length1And zero sequence resistance per unit length r0Inductance l per unit length0(ii) a The distances d from the fault point to the measurement points M and N are calculated according to the following formulaMAnd dN：
Figure DDA0001701899820000011
Figure DDA0001701899820000012
In the formula, d is the distance between the measurement points M and N, and aMAnd aNCalculated by the following calculation:
Figure DDA0001701899820000013
Figure DDA0001701899820000014
Figure DDA0001701899820000018
and
Figure DDA0001701899820000019
calculated by the following calculation:
Figure DDA0001701899820000015
Figure DDA0001701899820000016
Figure DDA0001701899820000017

Description

Power line fault point positioning method
Technical Field
The invention belongs to the field of power transmission network fault monitoring, and particularly relates to a fault accurate positioning method based on distributed measured impedance.
Background
The continuous development of social economy, the scale of power networks is gradually increased, and high-voltage overhead power transmission lines are increased day by day, so that higher requirements are provided for safe and stable operation, monitoring and protection of power systems. The high-voltage overhead transmission line has a wide distribution range, and is complex in terrain crossing and easy to break down. The rapid and accurate fault location of the line is one of effective ways for ensuring the safe and stable operation of the system.
The current fault location method mainly comprises an impedance location method and a traveling wave location method. The impedance method is also called generalized fault analysis method. The distance measuring device calculates the impedance of a fault loop according to the voltage and the current measured when the overhead transmission line is in fault. Since the line length is proportional to the impedance, the distance from the installation of the device to the fault point can be determined from the calculated impedance and the reference impedance of the line. The traveling wave method is to measure the distance by using the traveling wave generated in the line by the fault transient. The transient traveling wave encounters uneven media such as transformer substations, fault points and the like in the transmission process and is refracted and reflected. The position of the fault point can be calculated through the measured wave head time and the transmission path of the traveling wave.
However, both methods also have disadvantages. Impedance methods often do not take into account fault arcs and post-fault ground impedances. In practical situations, if the fault is a non-metallic high-resistance ground, the equivalent impedance of the arc and the ground impedance after the fault will bring a large error to the measurement. On the other hand, the impedance measuring device is generally installed at a transformer substation, is greatly influenced by sag, and is difficult to ensure high precision in long-distance measurement.
As for the traveling wave ranging method, although it is not affected by the fault-to-ground situation compared to the impedance method, there are still two main problems. First, in complex lines such as overhead line-to-cable hybrid lines or T-line lines, traveling waves are refracted where the line wave impedance changes. In addition, due to the influence of measurement noise, the wave head of the main wave is difficult to identify in the actual ranging process. The second problem is that the traveling wave attenuates after being transmitted for a certain distance, and the rising edge becomes slow, so that the wave head time is not easy to determine. Therefore, in the case of high-precision positioning, the traveling wave ranging method still cannot well meet the precision requirement.
Disclosure of Invention
The invention aims to solve the problems of ground resistance, circuit sag and span errors in the impedance method and the traveling wave distance measurement method, and provides a method for positioning a fault point of a power circuit.
The invention provides a power line fault point positioning method, which is used for calculating the position of a fault point of a three-phase power line and comprises the following steps:
acquiring positive sequence current i of any measurement point M on line1MZero sequence current i0MAnd a positive sequence current i at another measuring point N on the line1NZero sequence current i0N；
Measuring basic data of the three-phase power line, including positive sequence resistance r1Inductance l per unit length1And zero sequence resistance per unit length r0Inductance l per unit length0；
The distances d from the fault point to the measurement points M and N are calculated according to the following formulaMAnd dN：
Figure BDA0001701899800000031
Figure BDA0001701899800000032
In the formula, daNDenotes d and aNProduct of (d), daMDenotes d and aMProduct of (2)
d is the distance between the measuring points M and N, obtained by measurement,
and a isMAnd aNCalculated by the following calculation:
Figure BDA0001701899800000033
Figure BDA0001701899800000034
while measuring the faulted phase voltage at point M
Figure BDA0001701899800000035
And measuring the faulted phase voltage at point N
Figure BDA0001701899800000036
Calculated by the following calculation:
Figure BDA0001701899800000037
Figure BDA0001701899800000038
kr and KlZero sequence current compensation coefficients of line resistance and inductance, respectively:
Figure BDA0001701899800000039
the method for locating the fault point of the power line provided by the invention can also have the following characteristics that: the method comprises the following steps of acquiring three-phase current waveforms of power lines at M points and N points on two sides of a fault point at the fault moment, and obtaining the following current parameters:
current i of phase A measured at point MAMB phase line current i measured on M pointBMC phase line current i measured on M pointCM(ii) a Current i of phase A measured at point NANAnd the current i of the B phase line measured on the N pointBNC phase line current i measured on N pointCN，
Then, the positive sequence current i of the M point of any measuring point is calculated by using a symmetric component method1MZero sequence current i0MAnd a positive sequence current i at another measuring point N on the line1NZero sequence current i0N。
The method for locating the fault point of the power line provided by the invention can also have the following characteristics that: wherein the current parameter is measured by a measuring device distributively installed on the three-phase power line.
The method for locating the fault point of the power line provided by the invention can also have the following characteristics that: wherein the current parameter is a signal measured at a first time of failure of the three-phase power line.
The method for locating the fault point of the power line provided by the invention can also have the following characteristics that: the first time refers to a time range capable of capturing the whole short circuit process, and the first time is started at the fault occurrence time before and is ended at the system switching-off time after.
The invention has the following functions and effects: according to the power line fault point positioning method, the line is directly measured when the three-phase power line has a fault, the positive sequence current i1M and the zero sequence current i0M of any measuring point M on the line and the positive sequence current i1N and the zero sequence current i0N of another measuring point N on the line are obtained through measurement, the distance between the fault point and the measuring points M and N is calculated through a calculation formula, and the measurement of the voltage and the current of the fault point is not introduced into the calculation formula, so that on one hand, the positioning method is not limited by the type of whether the fault is non-metallic high-resistance grounding or arc discharge and the like, and the position of the fault point can be calculated no matter whether the fault is resistance type metal grounding or high-resistance grounding; on the other hand, measuring device can distribute on the power transmission line, can have the influence that effectively reduces the sag to the range error, compares traditional transformer substation impedance range finding, and the precision is higher, and stability is better.
Drawings
FIG. 1 is a schematic diagram of a method for locating a fault point of a power line according to an embodiment of the present invention;
FIG. 2 is a waveform diagram of phase A current in a practical example;
FIG. 3 is a waveform diagram of a phase B current in a practical example;
FIG. 4 is a waveform diagram of C-phase current in a practical example; and
fig. 5 is a schematic diagram showing a relationship between a distance between a measured measurement point M and a fault point and time in an actual example.
Detailed Description
In order to make the technical means, creation features, achievement objects and effects of the invention easy to understand, the following embodiments specifically describe the power line fault point positioning method of the invention with reference to the accompanying drawings.
Fig. 1 is a schematic diagram of a method for locating a fault point of a power line according to an embodiment of the present invention.
As shown in fig. 1, the measurement points are located at both ends of the X point where the fault occurs: measurement point M and measurement point N.
The positioning method comprises the following steps:
step S1, as shown in fig. 1, acquiring three-phase current waveforms of the power line at any M point and any N point on both sides of the fault point X at the first time of the fault occurrence by using the measuring devices distributed on the three-phase power line, to obtain the following current parameters:
current i of A phase line measured on measuring point MAM、
Current i of B phase line measured on M pointBM、
Current i of C phase line measured on M pointCM
And
current i of A phase line measured on N pointAN、
Current i of B phase line measured on N pointBN、
The current i of the C phase line measured on the N pointCN。
Step S2, calculating M point positive sequence current i by using a symmetrical component method1MZero sequence current i0MAnd a positive sequence current i of N point1NZero sequence current i0N。
Step S3, basic data of the three-phase power line are measured and obtained, and the basic data comprise positive sequence resistance r in unit length1Inductance l per unit length1And zero sequence resistance per unit length r0Inductance l per unit length0。
Measuring the faulted phase voltage at point M
Figure BDA0001701899800000063
And measuring the faulted phase voltage at point N
Figure BDA0001701899800000064
The relationship of (c) can establish the equation:
Figure BDA0001701899800000061
Figure BDA0001701899800000062
in the above formula, Kr and KlZero sequence current compensation coefficients of line resistance and inductance, respectively:
Figure BDA0001701899800000071
ufis the voltage from fault point X to ground as shown in figure 1.
To simplify the calculation, order
Figure BDA0001701899800000072
Figure BDA0001701899800000073
Substituting equation (2) into equation (1) can be derived as follows:
Figure BDA0001701899800000074
Figure BDA0001701899800000075
and according to the distance relation, the following results are obtained:
dM+dN＝d(4)
by combining the above equations (1), (2), (3) and (4), d can be derivedMAnd dN：
Figure BDA0001701899800000076
Figure BDA0001701899800000077
Thus, only step S4 needs to be performed: d is calculated according to the formulas (2), (3) and (5)MAnd dN。
The above steps S1 to S4 can obtain a simple distance between the fault point of the power line and the measurement point M and the measurement point N, that is, the position of the fault point X is determined. Obviously, the faulty phase voltages obtained by the above equations (1) and (2)
Figure BDA0001701899800000078
Faulted phase voltage
Figure BDA0001701899800000079
And an intermediate amount aMAnd aNRespectively, as a function of the measured current waveform, which is a variable over time, thus obtaining the distance dMAnd dNAnd is also a variable over time. At calculated dMAnd dNAnd selecting one section in the short circuit process, and averaging to obtain the finally calculated fault point positioning result.
In order to illustrate the practical effects of the method provided by the embodiment, a practical circuit case is provided below for explanation.
A110 kV power transmission line in Guangdong province in 5 months in 2018 has a fault. High-precision current measuring equipment is already installed on the tower 1# (measuring point M) and the tower 63# (measuring point N) of the line. The distance between the two measuring points is 18501 meters according to the data provided by the power supply bureau. The distribution parameters are shown in the table below.
Parameter per kilometer Resistance/omega inductor/mH
Positive sequence 0.0363 1.6014
Zero sequence 0.3795 4.2262
Fig. 2 is a waveform diagram of a phase a current in a practical example.
Fig. 3 is a waveform diagram of a B-phase current in a practical example.
Fig. 4 is a waveform diagram of a C-phase current in a practical example.
The ABC three-phase current waveforms collected at the two ends of the fault moment are shown in the attached figures 2, 3 and 4. (the waveform sampling rate is 3200Hz, the total number of points per waveform is 2000, so the sampling time is 625 ms).
Fig. 5 is a schematic diagram showing a relationship between a distance between a measured measurement point M and a fault point and time in an actual example.
According to the calculation method in the above-described steps, the values before and after the failure time are obtained as shown by the solid line in fig. 5. While the lower dashed line shows the location of the actual point of failure, i.e., 14978 m. According to the current waveform of each phase, the time from 70ms to 450ms in the diagram is a short-circuit current process (the current is in a normal operation state within 0-70ms, then the current is increased sharply to form a short-circuit current, the breaker is powered off after 450ms, and the rear current is zero), the time from 70ms to 450ms in the diagram is a first time, the first time is a time range capable of capturing the whole short-circuit process, the first time is a time range which should start from the fault occurrence time, namely 70ms in the diagram, and the second time is a time range which should end at the system opening time, namely 450ms in the diagram.
Therefore, take d of this timeMThe average value is 14773m, which is the positioning result in the fault process, and the calculated deviation is:
Figure BDA0001701899800000091
the above embodiments illustrate that by using the method, the fault location with higher precision can be performed by measuring the three-phase current of the power transmission line and combining the parameters of the line body.
Action and effect of the examples: according to the power line fault location method of the embodiment, because the line is directly measured when the three-phase power line fails, the positive sequence current i of any measuring point M on the line is obtained through measurement1MZero sequence current i0MAnd a positive sequence current i at another measuring point N on the line1NZero sequence current i0NThe distance between the fault point and the measuring points M and N is calculated through a calculation formula, and the measurement of the voltage and the current of the fault point is not introduced into the calculation formula, so that the positioning method is not limited by the types of whether the fault is nonmetallic high-resistance grounding or arc discharge point and the like on one hand, and the position of the fault point can be calculated no matter whether the fault is a resistance-type metal grounding or high-resistance grounding fault; on the other hand, measuring device can distribute on the power transmission line, can have the influence that effectively reduces the sag to the range error, compares traditional transformer substation impedance range finding, and the precision is higher, and stability is better.
In addition, in this embodiment, the parameters to be measured can be measured by using the hardware of the measurement device of the existing distributed measurement system for the power transmission line, and only the measurement functions of the power frequency voltage and the power frequency current need to be added, after the basic information of the line and the waveform of the fault moment are obtained, the obtained basic data of the three-phase power line are substituted into the calculation formulas (2), (3) and (5), so that d can be calculated and obtainedMAnd dNEasy implementation, easy equipment modification and easy popularization.
The present invention is not limited to the above-described embodiments, and it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and such modifications and improvements are also considered to be within the scope of the present invention. Those not described in detail in this specification are within the skill of the art.

Claims (4)

1. A power line fault point locating method for calculating the location of a fault point of a three-phase power line, comprising the steps of:
acquiring positive sequence current i of any measurement point M on line1MZero sequence current i0MAnd a positive sequence current i at another measuring point N on the line1NZero sequence current i0N；
Measuring basic data of the three-phase power line, including positive sequence resistance r1Inductance l per unit length1And zero sequence resistance per unit length r0Inductance l per unit length0；
The distances d from the fault point to the measurement points M and N are calculated according to the following formulaMAnd dN：
Figure FDA0002570875990000011
Figure FDA0002570875990000012
In the formula, daNDenotes d and aNProduct of (d), daMDenotes d and aMThe product d of (a) is the distance between the measurement points M and N, obtained by measurement,
and a isMAnd aNCalculated by the following calculation:
Figure FDA0002570875990000013
Figure FDA0002570875990000014
while measuring the faulted phase voltage at point M
Figure FDA0002570875990000017
And measuring the faulted phase voltage at point N
Figure FDA0002570875990000018
Calculated by the following calculation:
Figure FDA0002570875990000015
Figure FDA0002570875990000016
kr and KlZero sequence current compensation coefficients of line resistance and inductance, respectively:
Figure FDA0002570875990000021
ufis the fault point voltage;
the method comprises the following steps of acquiring three-phase currents of M points and N points on two sides of a fault point at a fault moment, and obtaining the following current parameters:
current i of phase A measured at point MAMB phase line current i measured on M pointBMC phase line current i measured on M pointCM(ii) a Current i of phase A measured at point NANAnd the current i of the B phase line measured on the N pointBNC phase line current i measured on N pointCN，
Then, the positive sequence current i of the point M of the measuring point is calculated by using a symmetric component method1MZero sequence current i0MAnd a positive sequence current i at another measuring point N on the line1NZero sequence current i0N。
2. The power line fault point locating method according to claim 1, wherein:
wherein the current parameter is measured by a measuring device installed on the three-phase power line.
3. The power line fault point locating method according to claim 1, wherein:
wherein the current parameter is a signal measured at a first time of failure of the three-phase power line.
4. The power line fault point locating method according to claim 3, wherein:
the first time refers to a time range capable of capturing the whole short circuit process, and the first time is started at the fault occurrence time before and is ended at the system switching-off time after.
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