JP2532155B2 - Fault location method for n-terminal parallel 2-circuit transmission line - Google Patents

Description

TECHNICAL FIELD The present invention relates to a one-phase ground fault fault locating method in a resistance grounding system n-terminal parallel two-line power transmission line.

<Prior art> Transmission lines between substations are
Generally, it is done with two parallel lines. The above-mentioned power transmission line is inevitably defective due to outside (dielectric breakdown due to lightning strike, contact with birds or trees, etc.) as compared with substations and the like that are maintained and managed in the building. Most of the faults are one-phase ground faults, and when a fault occurs, ground fault fault point search work is involved, but it may be very difficult to find a fault point especially in a mountain area.

As an example of the above failure, a failure at one point on one line,
There are failures at different points on one circuit, failures at the same point on both circuits, and failures at different points on both circuits. The above faults are generally referred to as simple faults, and the faults are generally referred to as multiple faults, but most of the faults are simple faults and most of the multiple faults are of the form. The present application deals with the above case.

Conventionally, various methods for locating a ground fault point have been proposed and implemented.

For example, the zero-phase current 01, 02 of each line of the two-terminal parallel two-line transmission line is detected, and the shunt ratio 20i / (01 + 02) of the zero-phase current is calculated (where i = 1 or 2), and There is a method of calculating the distance from the power transmission end to the one-phase ground fault point based on the zero-phase current diversion ratio and the transmission line length.

FIG. 8 is a diagram for explaining the above method, in which a YY type transformer c having a high resistance b and a neutral point grounded is arranged on the power transmission side a, and a non-contact on the power reception side d. A grounded Y-Δ transformer e is arranged. The transformers c and e are connected to bus lines g1 and g2, and two-line transmission lines f1 and f2 having a length of 1 are connected between these bus lines g1 and g2. FIG. 9 is the zero-phase equivalent circuit of FIG. 8, where the zero-phase current of line f1 is 01, the zero-phase current of line f2 is 02, the zero-phase voltage of bus 01 is o, the zero-phase voltage at the ground fault point. Is the zero phase impedance per unit length, and the mutual impedance between lines is m.

In the parallel 2-circuit transmission line, assume a case where a one-phase ground fault occurs at a distance x from the transmission end, and a ground fault current of 0f is flowing from the ground fault point to the ground. If the zero-phase current ratio is calculated for, the distance x from the power transmission end to the one-phase ground fault point can be calculated. That is, the one-phase ground fault point can be located only on the basis of the zero-phase currents 01 and 02 of the lines f1 and f2.

The above-described one-phase ground fault fault point calculation method based on the zero-phase current diversion ratio calculates the distance from the power transmission end to the fault point based on only the diversion ratio of the zero-phase current detected from each line at the power transmission end. Therefore, it cannot be applied as it is to a method of connecting a load by providing a branch in a power transmission line, that is, locating a one-phase ground fault point in a three-terminal system.

Therefore, the applicant of the present application has filed a method for enabling a one-phase ground fault point to be located by the zero-phase current shunting ratio method even in a resistance-grounded three-terminal parallel two-line power transmission line (Japanese Patent Application No. 63-63).
-169739 (see Japanese Patent Laid-Open No. 2-19779).

This method calculates the distance from the power transmission end to the 1-phase ground fault point or the distance from the 2-circuit branch point to the 1-phase ground fault point based on the transmission line length of the resistance grounding 3-terminal parallel 2-line transmission line. A correction coefficient for calculation is calculated in advance, and the zero-phase current detected at the power transmission end and the correction coefficient are used as elements.
This is a method of calculating the distance from the power transmission end to the ground fault point, or the distance from the two-circuit branch point to the ground fault point.

However, in this method, only the information on the transmitting end is used, and only the above-mentioned simple failure can be applied.

Therefore, the applicant of the present application has applied for a fault point locating method for a resistance grounding 2-terminal parallel 2-line transmission line and a 3-terminal parallel 2-line transmission line that enables both simple faults and multiple faults to be located. Sho 63-307612 (JP-A-2-154168)
See description).

This method is derived as follows by analyzing a zero-phase equivalent circuit of a resistance grounding system three-terminal parallel two-line and replacing it with an equivalent circuit based on zero-phase difference current (hereinafter abbreviated as difference current equivalent circuit).

FIG. 10 (A) shows a three-terminal parallel two-line power transmission line. The distance from the power transmission end to the branch point is la, and the branch point is two.
The distances to the two receiving ends are lb and lc, respectively. l
a, lb, lc are known values because they are the length of the transmission line.
The zero-phase equivalent circuit of the three-terminal parallel two-line power transmission line is shown in FIG. 10 (B), and the differential current equivalent circuit obtained based on the difference in the zero-phase currents of the respective lines is shown in FIG. 10 (C).

In Fig. 10 (C), the differential current flowing from the transmitting end A to the two-circuit branch point is Δ0a, and the differential current flowing from each receiving end B and C to the branch point flows out from Δ0b, Δ0c, and the one-phase ground fault point, respectively. The difference current is Δ0f. When a one-phase ground fault occurs between the power transmission end A and the branch point, the zero-phase current shunt ratio Using, Is represented. Here, L = lalb + lblc + lalc.

However, when x is larger than la, that is,
If it can be considered that the one-phase ground fault has occurred farther than the branch point, the zero-phase difference current shunt ratio The distance from the receiving end C to the failure point Is calculated, and when x is smaller than lc, this x is taken as the distance from the power receiving end C to the ground fault point (Fig. 10 (D)).
reference).

When x is larger than lc, zero phase difference current shunt ratio Using, Is calculated and this x is the distance from the power receiving end B to the ground fault point (see FIG. 10 (E)).

Therefore, L / (lb + lc), L / (lc + la) in the equation,
Alternatively, L / (la + lb) is used as the correction coefficient, and the transmitting end A and receiving end are
By detecting the zero-phase current from each line on the B and C sides and multiplying the zero-phase difference current shunt ratio by the correction coefficient, the distance x from each end to the one-phase ground fault point can be obtained.

<Problems to be Solved by the Invention> However, in the fault point locating method in the above-mentioned three-terminal parallel two-line transmission line, the ground fault point of the three-terminal parallel two-line can be obtained, but the number of terminals is less than three. Parallel 2
Not applicable to line transmission lines.

In recent years, parallel two-circuit power transmission lines tend to have multiple terminals, and a ground fault fault locating method applicable to general n-terminal parallel two-circuit power transmission lines is desired.

On the other hand, at present, the protection of parallel two-line power transmission line is also advanced method, for example, the current information of each terminal is collected in the master station by wireless transmission or optical transmission, and the system fault judgment is performed by the comprehensive judgment of the current information of all terminals. A differential protection method is adopted. Therefore, since the current data of each terminal is always collected in the master station, it is possible to obtain the basic data for locating the ground fault point by analyzing the information from immediately after the occurrence of the failure to the line interruption. it can.

The present invention extends the above-mentioned failure point locating method at the beginning, and based on the electronic information of each terminal, provides a failure point locating method for an n-terminal parallel two-line power transmission line applicable to a general n-terminal parallel two-line power transmission line. The purpose is to provide.

<Means and Actions for Solving the Problems> FIG. 2 is a diagram showing an n-terminal parallel two-line power transmission line to which the present invention is applied, and shows a power transmission end connected by two-line power transmission lines f1 and f2. N-2 branch points b2, b3, ..., bn-3, bn-2, b between a power receiving end (hereinafter collectively referred to as "terminal") 1 and a terminal n.
n-1 exists, and terminals 2, 3, ..., N-1 are connected to each branch point through two-line power transmission lines f1, f2. Terminal 1 and branch point b2
Is l1, the distance between terminal 2 and branch point b2 is l2, the branch point
It is assumed that the distance between b2 and b3 is l3, ..., The distance between the terminal k and the branch point bk is l2k-2, and the distance between the branch points bk and bk + 1 is l2k-1.
Line f1 zero-phase current flowing from terminal 1 is 11, line f2 zero-phase current flowing from terminal 1 is 12, line flowing from terminal k
The zero-phase current of f1 is k1, and the zero-phase current of the line f2 flowing from the terminal k is k2.

FIG. 3 is a differential current equivalent circuit using the zero phase difference current of the line of FIG. 2 above, and the zero phase difference current Δ from each terminal 1, 2, ..., N.
1, Δ2, ..., Δn are flowing out. However, the definition of the difference current is Δk = k1−k2.

There are two possible ground fault points, FIGS. 4 (a) and 4 (b). That is, when the ground fault point is between the branch point bk and the terminal k, the distance from the terminal k to the ground fault point is x. When the ground fault point is between the branch point bk and the branch point bk + 1, the distance from the branch point bk to the ground fault point is y. Let the outflow fault current in line f1 at the fault point be f
1. The outflow fault current in the line f2 is defined as f2, and the fault differential current is defined as Δf = f1−f2, but either f1 or f2 may be zero.

In the equivalent circuit of FIG. 3 described above, the following equivalent conversion is performed so that the equivalent circuits of FIGS. 10 (C) to 10 (E) can be used to locate the failure point. 5 (a) and (f) are
FIG. 9 is a diagram showing the principle of equivalent conversion, in which a circuit having a terminal 1, a terminal 2 and a branch point b2 (see FIG. 5 (a)) is replaced by a circuit having a virtual terminal 2 ′ and having no branch point (the fifth circuit). (See (f) figure). The conditions for this conversion are
The difference current Δ (= Δ1 + Δ2) flowing out from the branch point b2 of the circuit of FIG. 5 (a) before conversion and the difference voltage Δ are the difference current Δ flowing out from the right end b2 of the circuit of FIG. 5 (f) after conversion.
Is equal to the difference voltage Δ. As a result of this conversion, the virtual differential current Δ2 ′ flowing from the virtual terminal 2 ′ is Δ2 ′ = Δ1 + Δ2 = Δ, and the distance l2 ′ from the virtual terminal 2 ′ to the right end b2 of the line is l2 ′ = l1l2 / (l1 + l2), Can be represented.

If the circuit before conversion having the terminal 1, the terminal 2 and the branch point b2 has a failure point between the terminal 1 and the branch point b2 as shown in FIG. The differential current Δ (= Δ1 + Δ) flowing out from the branch point b2 of the circuit in FIG.
2- (Δf) and the difference voltage Δ are shown in FIG. 5 (g) after conversion.
As a result of equivalent conversion under the condition that it is equal to the difference current Δ and the difference voltage Δ flowing out from the right end b2 of the circuit, the distance x ′ of the virtual fault point can be expressed as x ′ = x (l2 ′ / l1) (fifth (See FIG. (G)). x is the actual distance from terminal 1 to the fault point. Note that the virtual difference current Δ
2'and the virtual distance l2 'have the same values as in the case of FIG. 5 (f).

Further, when the circuit before conversion including the terminal 1, the terminal 2 and the branch point b2 has a failure point between the terminal 2 and the branch point b2 as shown in FIG. The difference current Δ = (Δ1 + Δ) flowing out from the branch point b2 of the circuit in FIG.
2- (Δf) and the difference voltage Δ are shown in FIG. 5 (h) after conversion.
As a result of equivalent conversion under the condition that it is equal to the difference current Δ and the difference voltage Δ flowing out from the right end of the circuit, the distance x ′ of the virtual fault point can be expressed as x ′ = x (l2 ′ / l2) (FIG. 5). (See (h)). Also, the virtual difference current Δ
2'and the distance l2 'have the same values as in the case of FIG. 5 (f).

In this way, the inverted L-shaped differential current circuit shown in FIG. 5 (a) can be converted into the simple linear differential current circuit shown in FIG. 5 (f), and the inverted L-shaped differential current circuit shown in FIG. It is understood that the failure points shown in () can be converted into the virtual failure points shown in FIGS. 5 (g) and 5 (h), respectively.

 The validity of the above method will be described.

5 (d) and 5 (e) show the voltage Δb at the branch points b21 and b22.
Current flowing out of 21, Δb22 and branch points b21, b22
It is a circuit diagram for proving that both circuits are equivalent in the meaning that b21 and b22 are equal.

Zero phase self impedance per unit length of line is o,
If the zero-phase mutual impedance of both lines is m, then
The following equation is established for FIG.

 For the line f1, b21 = 1−xo 11−xm 12 − (l1−x) o (11−f1) − (l1−x) m (12−f2) When the above right side is rearranged, b21 = 1−l1 ( o11 + m12) + (l1-x) (of1 + mf2) Moreover, b21 = 2-l2 (o21 + m22) is established.

 From these two equations, b21 / l1 + b21 / l2 = 1 / l1 + 2 / l2-{o (11 + 21) + m (12 + 22) + (1-x / l1) (o f1 + m f2) is derived. (L21 + l12) / (l1 + l2)-{l1l2 / (l1 + l2)} {o (11 + 21) + m (12 + 22)} + {(l1l2-xl2) / l1 + l2)} × (of1 + mf2). Regarding the current, b21 = 11 + 21-f1 holds.

 Similarly for the line f2, b22 = (l21 + l12) / (l1 + l2)-{l1l2 / (l1 + l2)} {o (12 + 22) + m (11 + 21)} + {(l1l2-xl2) / (l1 + l2)} X (of2 + mf1) b22 = 12 + 22-f2 holds.

 Therefore, if we define 2 '= (l21 + l12) / (l1 + l2) 21' = 11 + 21 22 '= 12 + 22 l2' = l1l2 / (l1 + l2) x '= xl2 / (l1 + l2), the above formula is b21 = 2 '-L2' (o21 '+ m22') + (l2'-x ') (of1 + mf2) b21 = 21'-f1 b22 = 2'-l2' {o22 '+ m21'} + (l2'-x ') (of2 + mf1 ) We can write b22 = 22'-f2.

These four equations are equations that hold for the circuit of FIG. 5 (e).

Rewriting b21, b21, b22, b22 appearing in the above four equations using the following four equations Δ1 = 11-112 Δ2 = 21-22 Δf = f1−f2 Δ2 ′ = 21′−22 ′, the differential current = Calculate b21−b22 and the differential voltage Δ = b21−b22. Then, Δ = −l2 ′ (o−m) Δ2 ′ + (l2′−x ′) (o−m) Δf, Δ = Δ2′−Δf, and these two equations are obtained by the circuit of FIG. 5 (g). At
It is nothing but the equation that holds for the differential voltage Δ at the branch point b2 and the differential current Δ that is shunted from the branch point b2.

5 (a) and 5 (f) are shown in FIGS. 5 (b) and 5 (g).
In the case of f1 = f2 = 0 in FIG.
(H) shows terminals 1, 2, and 2 in FIGS. 5 (b) and (g).
The distances l1 and l2 and the difference currents Δ1 and Δ2 are exchanged.

Next, the fault location procedure will be described. First, the first
Regarding the differential current equivalent circuit shown in FIG. 3 (a) (FIG. 1 (a) is a reprint of FIG. 3), an inverted L-shaped differential current circuit having terminals 1, 2, and branch point b2 Locate the point of failure.

First, a differential current equivalent circuit including this reverse L-shaped differential current circuit can be converted into a T-type three-terminal parallel two-line transmission line circuit as shown in FIG. 1 (c). In FIG. 1 (c), the virtual terminal 3'is an equivalent conversion of the actual terminals 3, 4, ..., N, and the virtual difference current Δ3 'flowing out from it is Δ3' = Δ3 + Δ4 + Takes a known value represented by + Δn. Also, the virtual distance from the branch point b2 to the virtual terminal 3'is represented by l3 '.

The virtual distance l3 'is the terminal n, the terminal n-1, the branch point bn-1.
The inverse L-shaped differential current circuit having the above is converted into the linear equivalent circuit (the virtual distance is ln-1 ') having the virtual terminal n-1' in FIG. , Virtual terminal n-1 ', terminal n-2, and branch point bn-2 of FIG. 1 (b).
For an inverted L-shaped differential current circuit having
Can be obtained by converting the equivalent circuit (having an imaginary distance of ln-1 ') and repeating the same procedure. That is, in each linear equivalent circuit, the virtual distance l
n-1 ', ln-2', ..., l3 'are Becomes

A fault point is located in the circuit of FIG. 1 (c).
The method is based on the previous application (Japanese Patent Application No. 63
-307612), but once again explained using Δ1, Δ2 and Δ3 ′,
The distance x from the virtual terminal 3'to the failure point is set to L = l1l2 + l2l3 '+ l3'l1 and calculated based on the following equation.

If this x is smaller than l3 ', the fault point is between the branch point b2 and the virtual terminal 3', but if x is greater than l3 ', the fault point is from the terminal 1 to the branch point b2. Or between terminal 2 and branch point b2, Or The actual distance of the fault point from terminal 1 or terminal 2 can be determined accordingly.

If the failure point is between the branch point b2 and the virtual terminal 3 ', the method of the prior application cannot be used. In this case, the actual failure point is located at any position from the branch point b2 in FIG. 1 (a) to the right side and the terminals 3, 4, ..., N.

Therefore, the circuit having the terminal 1, the terminal 2, and the branch point b2 is converted by the conversion method already described to be a linear equivalent circuit having the virtual terminal 2 ', and the circuit on the right side of the branch point b4 is converted by the same method. Is converted into a linear equivalent circuit having a virtual terminal 4 '. As a result, a T-shaped equivalent circuit centered on the terminal 3 as shown in FIG. The virtual difference current Δ2 ′ flowing from the virtual terminal 2 ′ has a known value represented by Δ2 ′ = Δ1 + Δ2 and the virtual difference current Δ4 ′ flowing from the virtual terminal 4 ′ has a known value represented by Δ4 ′ = Δ4 + ... + Δn. The virtual distance l2 ′ is Then, the virtual distance l4 'can be obtained by a method of performing equivalent conversion from the right end of the circuit of FIG. 1 (a) as described above.

The method of the above-mentioned prior application is applied to this circuit.
As a result, if The value calculated by (L = l2'l4 + l4l '+ l4'l2') is l4
If x is smaller than the above, that is, it is between the terminal 3 and the branch point b3, this x is the distance from the terminal 3 to the failure point.

Otherwise, If the value calculated by is smaller than l2 ', that is, if the failure point is between the virtual terminal 2'and the branch point b3,
It can be seen that the fault point is between the branch point b2 and the branch point b3. It is already known that the failure point is located at any position from the branch point b2 to the right side and the terminals 3, 4, ..., N by the method described with reference to FIG. 1 (c). Because.

The failure point is the distance from the virtual terminal 2'where the calculated value x is, and the distance y from the branch point b2 can be obtained by y = x- (l2'-l3).

If none of the above cases applies, the failure point is located at any position from the branch point b3 to the right side and the terminals 4,5, ..., N. Therefore, with the terminal 4 as a reference, the left and right circuits are equivalently converted from the branch point b4 to form a T-shaped equivalent circuit, and the above fault point locating method is repeated.

As described above, the failure point is
, N-1 to the branch points b2, b3, ..., bn-1 respectively, the distance x from the terminal can be obtained. Further, when it is between the branch point bk and the branch point bk + 1, the distance of the failure point in the section can be obtained in the same manner as the y value calculation described above.

In addition, in the above description, the calculation of the failure point is performed by referring to FIG.
The T-type equivalent circuit is made with reference to the left end branch point b2 of the differential current equivalent circuit of, and thereafter, the branch points b2, b until the failure point is found.
I made T-type equivalent circuits one after another based on 3, b4, .... However, in the present invention, for example, first, the right end branch point b
Even if a T-type equivalent circuit is made with n-1 as a reference, and then T-type equivalent circuits are made one after another with reference to branch points bn-2, bn-3, bn-4, ... until a failure point is found. Well, generally, a T-type equivalent circuit is created with an arbitrary branch point bk as a reference, and thereafter, branch points bk + 1, bk + 2, bk + 3, ... And branch points bk-1, bk- until a fault point is found. It is sufficient to make a T-type equivalent circuit based on 2, bk-3, ....

<Example> Hereinafter, an example of a fault point locating method for a parallel two-line power transmission line of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 6 is a diagram in which a fault point locating device is connected to a four-terminal parallel two-line power transmission line applied to the fault point locating method according to the present invention, in which the master station device at the power transmitting end 1 is connected to the power receiving end 2, 3,4
At the terminal device is provided.

The master station device at the power transmission end 1 includes a CT (current transformer) 11 that detects the currents 1a, 1b, and 1c of the A-phase, B-phase, and C-phase of the line f1 and the A-phase, B-phase, and C-phase of the line f2. Current 2a, 2b,
CT12 that detects 2c and the currents 1a, 1b, 1c, 2a, 2b and 2c of each phase detected by CT11 and 12 are input,
An input section 13 that is insulated by an auxiliary CT (not shown) and that converts into a current signal of a predetermined level, and an A / D conversion section 14 that converts a current signal of a predetermined level from the input section 13 into digital data at a predetermined sampling cycle. , A data memory 15 for storing the digital data converted by the A / D converter 14.
Then, a predetermined calculation (described later) is performed based on the current data of the lines f1 and f2 stored in the data memory 15, and it is detected that a ground fault point has occurred in the two parallel lines. A CPU 16 for calculating the position of a failure point based on the current data detected at the end side and the current data transmitted from the power receiving ends 2-4, and a transmission unit for transmitting the current data with the power receiving ends 2-4. 17 and a display unit 18 for displaying information such as the distance to the failure point calculated by the CPU 16.

On the power receiving end 2 side, CT21 that detects the A-phase, B-phase, and C-phase currents 1a, 1b, and 1c flowing in the line f1, and the A-phase, B-phase, and C-phase currents 2a and 2b that flow in the line f2. CT22 detecting 2c
And an input section 23 that performs the same function as described above, and an A / D
It has a conversion unit 24, a data memory 25, a CPU 26, and a transmission unit 27.

CT31 that detects the currents 1a, 1b, 1c of the phases of the line f1 and the currents 2a, 2b, 2c of the phases of the line f2 at the power receiving end 3
CT32 for detecting the, the input unit 33 that performs the same function as described above, the A / D conversion unit 34, the data memory 35, and the CPU 36.
And a transmission section 37 are provided, and the CT41 for detecting the currents 1a, 1b, 1c of the respective phases of the circuit f1 on the power receiving end 4 side is provided at the power receiving end 4.
And CT that detects the current 2a, 2b, 2c of each phase of line f2
42, an input unit 43, an A / D conversion unit 44, and a data memory 45
A CPU 46 and a transmission unit 47 are provided.

The operation of the fault point locating device having the above configuration is as follows. That is, the current values flowing through the lines f1 and f2 at the respective terminals 1 to 4 detected by the CTs 11, 12, 21, 22, 31, 32, 41 and 42 are at predetermined levels in the input sections 13, 23, 33 and 43. The current signal of the predetermined level is converted into a current signal and the A / D conversion unit 14,
The data is converted into digital data at 24, 34, 44 at a predetermined sampling cycle and stored in the data memories 15, 25, 35, 45.

Then, based on the current data of the lines f1, f2 stored in the data memory 15, 25, 35, 45, the CPU 16, 26, 36, 46
Is the zero-phase current 11,12,21,22,31,32,41,4
Calculate 2.

Furthermore, each CPU16,26,36,46 is
The zero phase difference currents Δ1, Δ2, Δ3, Δ4 of f1 and f2 are obtained.

Δ1 = 11-12, Δ2 = 21-22, Δ3 = 31-32, Δ4 = 41-42 Next, the CPU 16 on the power transmission end 1 side determines that a failure has occurred when Δ1 exceeds a predetermined value. , The receiving end 2 in the transmitter 17
Request to transmit the data Δ2, Δ3, Δ4 of the zero phase difference currents of both lines f1 and f2 detected in .about.4.

Then, the data of Δ2, Δ3, and Δ4 are transferred to the transmission units 27, 3
It is sent to the transmission unit 17 and the CPU 16 via 7,47.

Next, the CPU 16 on the power transmission end 1 side calculates Δ calculated on the self end side.
1 and Δ on the receiving end 2, 3, 4 side obtained via the transmission unit 17
Fault location is performed using 2, Δ3 and Δ4 and the lengths of the lines f1 and f2 as elements.

Hereinafter, in this embodiment, it is assumed that an actual ground fault occurs between the power receiving end 3 and the branch b3 in FIG. 6 and a fault current f flows (for a person who is trying to locate a fault point, a ground fault). It is of course unknown where the tangle is.)

FIG. 7 is a flow chart showing a procedure for locating a fault point in the CPU 16 described above. In step, the reverse L-shaped differential current circuit including the power receiving end 4, the power receiving end 3 and the branch point b3 is converted by the conversion method already shown. , A straight-line equivalent circuit having a virtual power receiving end 3 '(virtual distance is l3'), and a T-shaped equivalent circuit having a power transmitting end 1, a power receiving end 2, and a virtual power receiving end 3'is made (Fig. 1 (See (c)).

Next, in the step, The failure distance x seen from the power transmission end 1 is calculated based on In the step, if x ≦ l1, the failure point is the power transmission end 1
Since it can be considered that it is between the branch point b2 and the branch point b2, this x is the distance from the power transmission end 1 to the failure point.

If x> l1, the process proceeds to the step, and the failure distance viewed from the power receiving end 2 is obtained. If x ≦ l2, it can be considered that the failure point is between the power receiving end and the branch point b2. Therefore, this x is the distance from the power receiving end 2 to the failure point. If x> l2, go to step. In step, the distance from the virtual power receiving end 3'to the fault point is obtained, and in step, it is compared with the virtual distance l3 '. In the step, the failure point is not between the power transmitting end 1 and the branch point b2, and in the step, it is determined that there is no failure point between the power receiving end 2 and the branch point b2.
It is theoretically inferred that it is within the virtual distance l3 'from the virtual power receiving end 3'. Therefore, x≤l3 'should be satisfied at the failure position shown in FIG. In this sense, the procedure of step may be omitted.

Next, in the step, the branch point b3 is used as a reference to convert into a T-type equivalent circuit of the power receiving end 3, the power receiving end 4 and the virtual terminal 2 '. This T-type equivalent circuit is shown in FIG.
The virtual power receiving end 4 ′ is replaced with the true power receiving end 4. This is because the transmission line in the embodiment shown in FIG. 6 has only two branch points b2 and b3. In the step, the failure distance from the power receiving end 4 is calculated. If the distance x satisfies x ≦ l5 in the step, the fault point can be considered to be between the branch point b3 and the power receiving end 4. If x> l5, the determination from the power receiving end 3 is performed in step. In step, x is l4
If it is smaller than x, x can be the distance from the power receiving end 3 to the failure point. In the present embodiment, since it is assumed that the failure point has occurred from the power receiving end 3 to the branch point b3, YES is selected in this step.

If x> l4 in the step, it can be determined that the fault has occurred between the branch points b2 and b3 in the step, and the calculated fault point distance x from the virtual terminal 2 ′ and the virtual distance l2 ′ and Using l3, the distance y from the branch point b2 to the fault point can be obtained as y = x- (l2'-l3).

<Effects of the Invention> According to the present invention described above, the power receiving end 2, which has any failure point,
The distance x from the power receiving end can be obtained when the distance is between 3, ..., N-1 and the branch points b2, b3 ,. Further, when it is between the branch point bk and the branch point bk + 1, it is found that the failure point is located in the section,
Since the distance y from the branch point bk can be obtained, the ground fault point can be accurately located in the general n-terminal parallel two-line transmission line based on the current information of each terminal.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a single line diagram showing a method of locating a failure point in a general n-terminal parallel two-line transmission line, and FIG. 2 shows a general n-terminal parallel two-line transmission line. FIG. 3 is a circuit diagram, FIG. 3 is a differential current equivalent circuit in which FIG. 2 is represented by a differential current, FIG. 4 is a diagram illustrating positions of failure points in the differential current equivalent circuit, and FIG. 5 is an inverted L-shaped differential current equivalent circuit. Is converted into a T-type equivalent circuit, FIG. 6 is a single-line diagram showing a four-terminal parallel two-circuit transmission line to which the fault location method of the n-terminal parallel two-circuit transmission line of the present invention is applied, and FIG. FIG. 6 is a flow chart for explaining a fault point locating method in an n-terminal parallel two-line transmission line in the line, and FIGS. 8 to 10 are circuit diagrams for explaining the fault point locating method of the prior application. 1,2, ..., n: Terminal, b2, ..., k, ..., bn-1: Branching point, f1, f2: Fault current, Δf: Fault differential current

Front page continuation (72) Inventor Susumu Ito 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Kansai Electric Power Co., Inc. (72) Inventor Kyoji Ishizu 3-22-3 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Kansai Electric Power Co., Inc. (72) Inventor Tokuo Emura 47 Umezu Takaunecho, Ukyo-ku, Kyoto City, Kyoto Prefecture Nissin Electric Co., Ltd.

Claims (1)

(57) [Claims] 1. A grounding fault point when a one-phase ground fault occurs at one point of one line of a resistance grounding n-terminal parallel two-line transmission line, or both of a resistance grounding n-terminal parallel two-line transmission line. A method of locating a ground fault point when an in-phase ground fault occurs at the same point of the line based on the current measured at each terminal, which includes the following (a), (b), and (c): ), And either or both of (d) and (e), the distance from the terminal to the failure point is obtained. Point orientation method. (A) With reference to any of the branch points of the n-terminal parallel two-line power transmission line, of the branches at the branch point, the length of the branch is actually from the branch point to the terminal connected to the branch point. 3 including at least one branch k indicating the distance of
Equivalent conversion is performed into a T-type three-terminal parallel two-line transmission line circuit having two branches k−1, k, k + 1. (B) Three branches k−1 of this three-terminal parallel two-line transmission line,
Zero phase difference currents Δk−1, Δk, of both lines flowing in k, k + 1
Input Δk + 1, (However, lk-1; length of branch k-1 indicating virtual distance or actual distance, lk; length of branch k indicating actual distance, lk + 1; branch k + 1 indicating virtual distance or actual distance , X; is calculated based on the following equation: L; (lk-1 lk + lk lk + 1 + lk + 1 lk-1)). (C) When xk is smaller than lk, let xk be the distance from the terminal in the branch k to the fault point. (D) When xk is larger than lk, Xk-1 is calculated based on the following equation, and xk-1 and lk-1 are compared. If xk-1 is smaller than lk-1, lk-1 indicates the actual distance. If so, let xk-1 be the distance from the terminal at the branch k-1 to the fault point, and if lk-1 indicates a virtual distance, the length of the branch based on the branch point connected to the branch k-1. At least one branch k indicates the actual distance from the branch point to the terminal connected to the branch point
Equivalent conversion to a T-type three-terminal parallel two-line transmission line circuit having three branches k-2, k-1, k including -1 is performed. ), (C),
The procedure of (d) is repeated. (E) When xk is larger than lk, Xk + 1 is calculated based on the following formula, and xk + 1 and lk + 1 are compared. If xk + 1 is smaller than lk + 1, lk + 1 indicates the actual distance. If so, let xk + 1 be the distance from the terminal in branch k + 1 to the fault point, and if lk + 1 indicates a virtual distance, branch k
Three branches k, k + 1, k + 2 including at least one branch k + 1 whose length refers to an actual distance from the branch point to a terminal connected to the branch point with reference to the branch point connected to +1 Equivalent conversion is performed on the T-type 3-terminal parallel 2-line transmission line circuit having the above, and steps (b), (c), and (e) are repeated for this T-type 3-terminal parallel 2-line transmission line circuit.