JP3013491B2 - Short-circuit fault location method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for locating a short-circuit fault point in one line of a three-terminal parallel two-line transmission line.

[0002]

2. Description of the Related Art Transmission lines between substations are generally provided in a parallel two-circuit system in order to improve the reliability of power supply.
As compared with a substation or the like that is maintained and managed in a building, an external failure (dielectric breakdown due to a lightning strike, contact with a bird or a tree, etc.) is inevitable for this transmission line. Therefore, when a fault occurs, a fault point search operation is involved, and searching for a fault point, particularly in a mountainous area, may be very difficult.

[0003] Therefore, if the position and range of a fault point are specified (orientated) by calculation in advance, it is sufficient to search for the fault point within that range, which leads to more efficient work. Conventional method 3
As a method of locating a short-circuit fault at one point and one point in a two-terminal parallel transmission line, a method of calculating a shunt ratio by using a difference current between two lines at each terminal (see Japanese Patent Application Laid-Open No. 2-154168) is adopted. ing.

[0004] This system will be described for a three-terminal parallel two-circuit transmission line as shown in FIG. Each transmission line is 1L, 2L
And the three terminals are designated as A end, B end and C end, respectively, and the branch point is represented by T. The distances between AT, BT, and CT are d1, d2, and d3, respectively. A power supply (may be a transformer) TR is connected to the terminal A. A general load (not shown) is connected to the terminals B and C. At the A end, the B end, and the C end, the fault phase currents I1n, I2n, I1n ', I2n',
I1n ", I2n" (where n represents a failure phase, and the failure phase is one selected from the a phase, the b phase, the c phase, the positive phase, and the negative phase. However, the zero phase Is not included.), And a difference current ΔI = | I1n−I2n |, ΔI ′ = | I1n′−I2n ′ |, ΔI ″ = | I1n ″ −I2n ″ |, is calculated. In this specification, the notation "I"
Is a vector

[0005]

[Outside 1]

[0006] According to this method,
formula

[0007]

(Equation 1)

[0008]

(Equation 2)

[0009]

(Equation 3)

X, x ', x "are calculated by
If x is smaller than 1, x is the distance from the A end to the fault point. If x is larger than d1, x 'is compared with d2. If x' is smaller than d2, x is x. Is the distance from the end B to the fault point, and if x 'is greater than d2, x is the distance from the end C to the fault point. As described above, the current at each end is detected. Thus, the failure point can be located.

[0011]

In the above-mentioned method, the A-end,
It is necessary to collect all data from B-end and C-end,
If the data at the load end is lost due to a failure in the detection means, a failure in the data transmission line, or the like, the calculation cannot be performed. Accordingly, the present invention provides a method for locating a single-circuit short-circuit fault point in a three-terminal parallel two-line power transmission line having one or two power transmission ends and a load connected to the other end. It is an object of the present invention to provide a short-circuit fault locating method which can restore complete data by supplementing data with data at the other two ends and thereby locate a fault point.

[0012]

According to the first aspect of the present invention, there is provided a method comprising:
In the method of locating a single-circuit short-circuit fault point in a three-terminal parallel two-line power transmission line with one power transmission end and a load connected to the other two ends, current data at one end with the load connected was lacking. Fault phase difference current Δ at the end where another load is connected
In ′, the fault sum current ΣIn and the fault phase difference current ΔIn at the transmitting end are detected, and the fault phase difference at one end where the current data is missing is determined based on the equation ΔIn ″ = | ΣIn | − (ΔIn + ΔIn ′). The current ΔIn ″ is estimated and these fault phase difference currents ΔIn, ΔIn
This is a method for locating a one-line short-circuit fault using In 'and .DELTA.In ".

A method according to claim 2 for locating a single-circuit short-circuit fault point in a three-terminal parallel two-line transmission line having two power transmission terminals and a load connected to the other terminal.
When the current data at the end to which the load is connected is lost, the fault phase difference currents .DELTA.In and .DELTA.In 'and the fault phase sum currents .DELTA.In and .DELTA.In' at the other two ends are detected. '|-(ΔIn + ΔIn
′), The fault phase difference current ΔIn ″ at the missing one end is estimated, and these fault phase difference currents ΔIn, ΔIn ′ and ΔIn
This is a method of locating a one-line short-circuit fault point using In ".

[0014]

First, the first aspect of the present invention will be described with reference to FIG. FIG. 1 shows a three-terminal parallel two-circuit transmission line circuit to which the present invention is applied. Transmission end A and load end B,
The three-terminal parallel two-line transmission lines 1L and 2L are provided between the transmission terminal A and the load terminal C, and the distance between the transmission terminal A and the branch point T is d.
1, the distance between load end B and branch point T is d2, load end C
The distance between the point and the branch point T is d3.

It is assumed that a short circuit accident has occurred at the point F on the 1L line side, and a short circuit current IF has flowed. A end, B
I1n, I1n
2n, I1n ', I2n', I1n ", I2n". The short-circuit current IF is expressed by IF = I1n + I1n '+ I1n "(4) Since there is no failure on the 2L line side, it is expressed as 0 = I2n + I2n' + I2n" (5). By subtracting equation (5) from equation (4), IF = (I1n-I2n) + (I1n-I2n ') + (I1n "-I2n") (6) Since the currents at the terminals are almost in phase, equation (6) gives: | IF | = | I1n−I2n | + | I1n′−I2n ′ | + | I1n ″ −I2n ″ | = ΔIn + ΔIn ′ + ΔIn ″ (7 ) Can be written.

On the other hand, the sum I1n + I2n of the currents flowing through the 1L line and the 2L line at the end A is ΔIn, and the sum I1n ′ + I2n ′ of the currents flowing through the 1L line and the 2L line at the end B is ΔIn
', If the sum I1n "+ I2n" of the currents flowing through the 1L line and 2L line at the C end is "In", the short-circuit current IF is
It is equal to ΣIn + ΣIn '+ ΣIn ″, that is, IF = ΣIn + ΣIn' + ΣIn ″. Therefore, the expression (7) becomes | ΣIn + ΣIn ′ + ΣIn ″ | = | ΣIn | + | ΣIn ′ | + | ΣIn ″ | = ΔIn + ΔIn ′ + ΔIn ″.

However, .DELTA.In 'and .DELTA.In "are currents of the fault phase supplied to the load at the time of short-circuit fault, and are much smaller than short-circuit fault current IF. Therefore, this equation is given as | ΣIn | = ΔIn + ΔIn ′. + ΔIn ″, and this equation is rewritten as ΔIn ″ = | ΣIn | − (ΔIn + ΔIn ′) (8) This equation calculates the difference current at the load end C by the difference between the power transmission end A and the load end B. This indicates that the estimation can be performed using the current and the sum current of the power transmission end A.

In the above assumption, the current / voltage data at the load terminal C is missing. However, the case where the current / voltage data at the load terminal B is missing can be handled in the same manner. ΔIn ′ = | ΣIn | − (ΔIn + ΔIn ″) (9) Next, the invention of claim 2 will be described.FIG. 2 shows a three-terminal parallel two-line transmission line circuit to which the invention is applied.

Between the transmitting end A and the transmitting end B and between the transmitting end
A terminal parallel two-circuit transmission line is provided. The short-circuit current IF is expressed by IF = I1n + I1n '+ I1n "(10) Since there is no failure on the 2L line side, it is expressed as 0 = I2n + I2n' + I2n" (11). By subtracting equation (11) from equation (10), IF = (I1n-I2n) + (I1n'-I2n ') + (I1n "-I2n") (12) Since the currents at the terminals are almost in phase, equation (12) gives: | IF | = | I1n−I2n | + | I1n′−I2n ′ | + | I1n ″ −I2n ″ | = ΔIn + ΔIn ′ + ΔIn ″ (13 ) Can be written.

On the other hand, the short-circuit current IF is given by IF = ΣIn + ′ In '+ ″ In ″ Therefore, the expression (13) is given by | ΣIn + ΣIn ′ + ΣIn ″ | = | ΣIn | + | ΣIn ′ | + | ΣIn ”| '+ ΔIn ″.

However, {In} is the current of the fault phase supplied to the load in the event of a short-circuit fault, and is much smaller than the short-circuit fault current IF. Therefore, this equation is given as: | ΣIn | + | ΣIn '| = ΔIn + ΔIn ′ + ΔIn ″, and this equation is rewritten as: ΔIn ″ = | ΣIn | + | ΣIn ′ | − (ΔIn + ΔIn ′) (14) This equation calculates the difference current at the load end C by the transmission end. This indicates that the estimation can be performed using the difference current between the power transmitting end A and the power transmitting end B and the sum current of the power transmitting end A and the power transmitting end B.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The fault locating method of the present invention will be described below in detail with reference to the accompanying drawings. Note that the same reference numerals are used for components common to FIGS. 1 and 2 described above. FIG. 3 is a diagram showing a general three-terminal parallel two-circuit power transmission line and a fault point calculating device for implementing the fault point locating method according to the present invention;
In the three-terminal parallel two-circuit transmission line, a power supply or a transformer is arranged on the power transmission end A side, and loads are arranged on the load end B and load end C sides. The failure point calculation device 3A is arranged on the power transmission end A side.

The three-terminal parallel two-circuit power transmission line includes current transformers CT1A and CT2A connected to the 1L line and the 2L line at phases a, b, and c of the transmission end A, respectively. And a transformer 4A for detecting a line voltage. The fault point calculating device 3A converts the value read through the current transformers CT1A, CT2A and the transformer 4A into a voltage signal of a predetermined level representing each phase voltage and current. A sample-and-hold circuit 32A that samples at each angle (for example, 30 degrees), an A / D converter 33A, a receiver 34A that receives data of measured values at the load terminals B and C through wireless or light, and an A / D converter 33A. A failure detection unit 36A that detects a short-circuit failure based on the digital value converted by the above and the digital value of the measured value at the load terminals B and C read through the receiver 34A. When data is missing (hereinafter, it is assumed that data at the C end is missing), B
The fault phase difference current .DELTA.In 'at the end, the fault sum current .DELTA.In and the fault phase difference current .DELTA.In at the A end are detected, and the current data is lost based on the formula .DELTA.In "= | .DELTA.In.vertline. A data restoration unit 35A that calculates the fault phase difference current ΔIn ″ at the C end and supplies the distance detection unit 37A, and a distance calculation unit 37 that calculates the distance of the fault point based on the data supplied from the data recovery unit 35A.
A, and a display unit 38A for displaying the occurrence of a failure, the distance to the failure point, and the like are provided.

In the above description, the data restoration unit 35A
Although the current at the C end is restored when the C end current data is lost, the difference current at the B end can be similarly restored even when the B end current data is lost. The load terminal B is connected to the current transformers CT1B and CT2B connected to the a-phase, b-phase, and c-phase of the 1L line and the 2L line, and the bus on the load end B side to detect a line voltage. The transformer 4B is connected.

The measuring devices 3B include current transformers CT1B and CT1B.
2B and an input section 31B for converting a value read through the transformer 4B into a voltage signal of a predetermined level representing a current and a voltage of each phase.
Sampling and holding circuit 32 that samples every 30 degrees)
B, an A / D converter 33B, and a transmitter 34B for transmitting the data of the measurement value at the load end B via radio, light, or the like.

The load terminal C is connected to current transformers CT1C and CT2C connected to the 1L line, 2L line a-phase, b-phase and c-phase on the load terminal C side, and to a bus on the load terminal C side. The transformer 4C for detecting the line voltage is connected, and the current transformers CT1C and CT2 are connected to the measuring device 3C.
C and an input unit 31C for converting a value read through the transformer 4C into a voltage signal of a predetermined level representing each phase voltage and current, and converting the voltage signal of the input unit 31C to a predetermined electrical angle (for example,
Sampling and holding circuit 32 that samples every 30 degrees)
C, an A / D converter 33C, and a transmitter 34C that transmits data of the measured value at the load terminal C through radio, light, or the like.

The sample and hold circuits 32A, 32A
Sampling synchronization is adopted between B and 32C as described later so as not to cause an operation error. The operation of the fault point calculating device 3A is as follows. When the failure detection unit 36A detects a failure, it causes the distance calculation unit 37A to start a failure point locating operation. The distance calculation unit 37A extracts the data of the fault phase difference current from the data restoration unit 35A.

The distance calculating section 37A fetches the above data and detects a fault phase difference current ΔI at the power transmitting end A, a fault phase difference current ΔI 'at the power receiving end B, and a fault phase difference current ΔI ″ at the power receiving end C. The distance from any one of the ends A, B or C to the fault point is numerically calculated based on the known formulas (1), (2) and (3) shown below. Even if the current data of C is missing, based on the fault phase difference current and fault sum current data measured at the other end, the fault phase difference currents ΔIn, ΔIn ′ at the A and B ends and the fault sum at the A end By calculating the current ΣIn and applying the equation ΔIn ″ = | ΣIn | − (ΔIn + ΔIn ′), it is possible to restore the fault phase difference current data missing at the C end, which hinders the calculation of the distance. There is no.

Therefore, the current transformer, transformer, input section, sample and hold circuit, A / D of the measuring device 3B or 3C
It is also possible to omit the converter from the beginning. It should be noted that high-speed, high-reliability is required for data transmission between the fault point calculation device 3A, the measurement device 3B, and the measurement device 3C. Therefore, as a data transmission method, for example, PC
It is preferable to use the M transmission method and use a large capacity communication path. In particular, if the data sampling synchronization is not accurately obtained, an error occurs in the calculation result. Therefore, a so-called SP synchronization control technique (signal transmission between the transmitter 13 and the receiver 12) for accurately measuring and correcting the sampling time difference occurring during data transmission. To reciprocate and measure the time taken for the reciprocation to correct the sampling time difference.Mitsubishi Electric Technical Report Vol.
63, No. 8, 1989, pp. 27-31).

Although the present invention has been described based on the embodiments, the present invention is not limited to the above embodiments. For example, as shown in FIG. 4, even when a three-terminal parallel two-circuit transmission line is provided between the power transmission end A and the power transmission end B, and the load end C,
The fault phase difference currents ΔIn, ΔIn 'at A-end and B-end and A
故障 In, ΣIn 'at the end and the B end are calculated, and the equation ΔIn ″ = | ΣIn + ΣIn ′ | − (ΔIn + ΔIn
It is also possible to implement the invention according to claim 2 which complements the missing data at the C-end by applying ').

Further, a transmitter is installed at each of the power transmitting end A and the load terminals B and C to transmit data, and the fault point calculating device 3A is located at a place away from both the power transmitting end A and the load terminals B and C.
It is also possible to set up. Various other changes can be made without departing from the scope of the present invention.

[0032]

As described above, according to the first aspect of the present invention, when the current data at one load terminal is lost, the fault sum current and the differential current at the transmitting terminal and the differential current at the other load terminals are lost. By using the above data, the missing data can be complemented. According to the invention described in claim 2, 1
When the current data of two load terminals is lost, the missing data can be complemented by using the fault sum current and the difference current of the two power transmission terminals.

Therefore, it is possible to locate a short-circuit fault point of a three-terminal parallel two-circuit transmission line, and it is possible to search for a fault point with a small amount of labor.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the operation of the present invention (claim 1);
It is a failure phase equivalent circuit diagram of a three-terminal parallel two-circuit transmission line.

FIG. 2 is a view for explaining the operation of the present invention (claim 2);
It is a failure phase equivalent circuit diagram of a three-terminal parallel two-circuit transmission line.

FIG. 3 is a diagram showing a fault point calculating device applied to a fault point locating method in a three-terminal parallel two-circuit transmission line.

FIG. 4 is a diagram showing a fault point calculating device applied to a fault point locating method in a three-terminal parallel two-circuit transmission line.

FIG. 5 is a circuit diagram of a general three-terminal parallel two-circuit transmission line.

[Explanation of symbols]

 1L, 2L 3-terminal parallel 2-circuit transmission line 3A Fault point calculation device 3B, 3C measurement device 35A Data restoration unit 37A Distance calculation unit 4A, 4B, 4C Transformer A Transmitting end B Transmitting end or receiving end C Receiving end CT1A, 2A Current transformer CT1B, 2B Current transformer CT1C, 2C Current transformer

Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01R 31/08 H02H 3/26-3/30 H02H 3/32-3/52

Claims (2)

(57) [Claims] 1. A method for locating a single-circuit short-circuit fault point in a three-terminal parallel two-line power transmission line having one power transmitting end and a load connected to the other two ends. If the current data is missing, the fault phase difference current ΔIn ′ at the end to which another load is connected and the fault sum current Σ at the transmission end
In and the fault phase difference current ΔIn are detected, a fault phase difference current ΔIn ″ at one end where current data is missing is estimated based on the equation ΔIn ″ = | ΣIn | − (ΔIn + ΔIn ′), and these fault phase difference currents are detected. ΔIn, Δ
A method of locating a short-circuit fault point using In 'and .DELTA.In ". 2. A method for locating a single-circuit short-circuit fault point in a three-terminal parallel two-line power transmission line having two power transmission terminals and a load connected to the other terminal. If the data is missing, the fault phase difference currents .DELTA.In and .DELTA.In 'at the other two ends, and the fault sum currents .DELTA.In and .SIGMA.
In ′ is detected, and the equation ΔIn ″ = | ΣIn + ΣIn ′ | − (ΔIn + ΔIn
′), The fault phase difference current ΔIn ″ at the missing one end is estimated, and these fault phase difference currents ΔIn, ΔIn ′ and ΔIn
A method of locating a short-circuit fault point using In ".