JPH063402A - Fault locator - Google Patents

Abstract

PURPOSE:To locate a fault point with precision even with a branch power source by obtaining a decision value using a branch point voltage, branch point current and transmission line impedance (set value). CONSTITUTION:Input conversion circuits 4 and 5 convert the outputs of transformer 2 and converter 3 into appropriate level, and then they are A/D converted by an A/D converter 6, to be applied to a calculation circuit 7. In the calculation circuit 7, line length L1 from its own terminal (decision system installed terminal) to a branch point J1, line length LB from a branch power source P1 to the point J1, positive phase impedance Z1 per a unit length of a transmission line 1 and positive phase impedance ZB1 behind the power source P1 terminal are set and stored, and branch point voltage VJ1=V-Z1 L1I (V and I are voltage and current, respectively, at its own terminal), differential voltage V''=V-V', differential current I''=I-I' (V', I' and I' are voltage and current, respectively, before accident), positive phase impedance behind its own power source (P0) ZB0-V''/V'', branch point current IJ1=(1+(ZB0+Z1 L1)/(ZB1+Z1LB1): I, distance between the point J1 and a fault point (F) X2= VJ1/(Z1IJ1) and distance (assessment value) between its own terminal and the point (F) X=L1+X2 are calculated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fault point locator for locating a distance to a fault point by inputting voltage and current at one end of a transmission line, and more particularly to a fault locator for a transmission line having a branch power source. .

[0002]

2. Description of the Related Art Conventionally, there are a surge receiving system, a pulse radar system, an impedance measuring system and the like as a transmission line fault locating system. The former two require expensive communication equipment or signal coupling equipment to power lines. On the other hand, the latter impedance measurement method is based on the voltage and current obtained from the voltage transformer and the current transformer, and does not require new equipment to obtain the input amount. For this reason, the impedance measurement method has recently received a great deal of attention.

The conventional impedance measuring method is based on the assumption that the transmission line has no branch. If there is a branch, it is premised on the orientation up to the branch point. This is not a problem for the trunk transmission line. The reason is very limited even if there are branches, so even if a device is installed for each branch,
This is because the number of devices will not increase significantly. But,
In a low-order transmission line of 66 kv or the like, there are many leads to customers, and it is difficult to install a device for each lead in both economically and in operation.

Therefore, in a transmission line with many branches, a fault point locating method that is not affected by branch loads, for example, Japanese Patent Publication No. 60-220220 "Transmission line fault point locating method".
Etc. have been proposed.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The conventional method including the invention of No. 4220 presupposes that the transmission line has no branch power source. In the past, this has not been a problem in many subordinate transmission lines. This is because even if there is a branch power supply, its power supply capacity is small and can be ignored. However, recently, the application range of the fault locator has been expanded, and it is expected to be applied to a complicated transmission line having a branch power supply whose power capacity cannot be ignored. Therefore, the orientation error cannot be ignored.

The present invention has been made in view of the above circumstances, and provides a fault point locating device capable of performing highly accurate fault point locating even if there is a branch power source between the accident point and the locating device. Is intended.

[0007]

In order to achieve the above object, the fault point locating device of the present invention comprises a voltage / current reading means, a set value reading means, a branch point voltage calculating means, a change voltage and a change voltage. A current calculation means, a back impedance calculation means of the orientation device installation end, a branch point current calculation means,
It is composed of a reference value calculation means and a reference value output means.

[0008]

In the fault point locating device of the present invention, first, the voltage / current at the installation end of the locating device and the set value are read to obtain the branch point voltage. Next, the branch point current is calculated from the impedance behind the orientation device installation end and the impedance (setting value) behind the branch power source from the changed voltage and current. Then, a reference value is obtained from the branch point voltage, the branch point current, and the line impedance (set value) and output.

[0009]

Embodiments will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the hardware of an embodiment of the present invention. In FIG. 1, 1 is a target transmission line, 2 is a transformer, 3 is a current transformer, 4 and 5 are input conversion circuits, 6 is an analog-digital conversion circuit (AD conversion circuit), 7 is an arithmetic circuit, and 8 is Display circuit, P ₀ is a power source behind the locator installation end (self end), P ₁ is a branch power supply, J ₁ is a branch point, F is an accident point, L ₁ is a line length between the self end and the branch point J ₁ ,
L _B1 is the line length between the branch power source P ₁ and the branch point J ₁ , X ₂ is the distance from the branch point J ₁ to the fault point, and X is the fault point F to the fault point F.
Is a distance (reference value), V is a self-end voltage, and I is a self-end current. For example, V represents three-phase voltages V _a , V _b , and V _c ,
The three-phase currents I _a , I _b , and I _c are represented by I as a representative.

The input conversion circuits 4 and 5 convert the outputs of the transformer 2 and the current transformer 3 to an appropriate level and further remove a high frequency component from a pre-filter (known in the art, Output is generated via (omitted). An AD conversion circuit 6 (which is publicly known and an internal configuration diagram is omitted) samples an input at a constant interval, AD-converts it, and applies a digital output to the arithmetic circuit 7. The arithmetic circuit 7 performs the arithmetic operation described with reference to FIG. 2 and displays the result on the display circuit 8.

Here, the outputs of the input conversion circuits 4 and 5, AD
The digital output converted by the conversion circuit 6 is represented by V and I unless there is any confusion. Further, it is assumed that there is one branch power source / branch point and the accident point F is beyond the branch point J.

FIG. 2 is a block diagram for explaining the function of the arithmetic circuit 7 of FIG. The present invention is intended for accidents involving two or more lines. Further, although the symbolic expression is omitted, the voltage V and the current I use the line spacing. The conversion of each phase of voltage and current into the line is performed by a known method.

In FIG. 2, 9 is a setting means, which is L ₁ ,
L _B1 , Z ₁ , Z _B1, etc. are set and stored. L ₁ ,
L _B1 is the same distance as in FIG. 1, Z ₁ is the positive phase impedance per unit length of the transmission line, and Z _B1 is the positive phase impedance behind the branch power source P ₁ end. Numeral 10 is a calculating means which receives the voltage V, the current I and the constants Z ₁ and L ₁ as input and performs the following calculation to output a branch point voltage output V _J1 . However, * indicates multiplication. V _J1 = V−Z ₁ * L ₁ * I …………………………………… (1). Numeral 11 is a calculation means for inputting the voltage V and the current I and performing the following calculation to output the changed voltage V ″ and the changed current I ″. Here, V ': voltage before accident, I': current before accident. V ″ = V−V ′, I ″ = I−I ′ (2) 12 is a calculating means for performing the following calculation and outputting the positive phase impedance Z _B0 behind the self-end power supply P _0. To do. Z _B0 = V ″ / I ″ (………………………………………… (3) 13 is the calculation means to perform the following calculation and output the branch point current I _J1 . I _J1 = (1+ (Z _B0 + Z ₁ * L ₁ ) / (Z _B1 + Z ₁ * L _B1 )) * I (4) 14 is the calculating means for performing the following calculation and outputting the distance X ₂ . X ₂ = V _J1 / (Z ₁ * I _J1 ) ... (5) 15 is a calculation means for performing the following calculation and outputting the reference value X. X = L ₁ + X ₂ …………………………………………………… (6)

FIG. 3 is an equivalent circuit for explaining the operation of the calculating means 11 and 12 of FIG. 3A is an equivalent circuit at the time of an accident, FIG. 3B is an equivalent circuit of the pre-accident component, and FIG. 3C is an equivalent circuit of the accident component. The phenomenon when an accident occurs is decomposed into two equivalent circuits of the pre-accident component and the accident component as shown in FIG. Therefore, the positive-phase impedance Z _B0 behind the self-terminal is changed from the figure (c) using the change (difference between the pre-accident component and the accident component) voltage V ″ and the change current I ″ (equation (2) above). It is obtained by the equation (3).

FIG. 4 is a diagram for explaining the overall operation of FIG. First, the voltage VJ ₁ at the branch point J ₁ is obtained by the equation (1) by subtracting the voltage drop between the local end from Zidane voltage V and the branching point J ₁ (computing means 10). Next, the impedances Z _J10 and Z _J11 seen from the branch point J ₁ to the self end and the branch power supply end are respectively _{calculated as} follows. Z _J10 = Z _B0 + Z ₁ * L ₁ …………………………………… (7) Z _J11 = Z _B1 + Z ₁ * L _B1 …………………………………… (8) The inflow current I _B1 from the branch power source is obtained as follows using the self-end current and the impedances Z _J10 and Z _J11 . Z _B1 = (Z _J10 / Z _J11 ) * I ………………………… (9) Also, the current I _J1 at the branch point J ₁ is the sum of the currents I and I _B1. The following is obtained using the equations (7) to (9) (calculating means 13). I _J1 = I + I _B1 = (1+ (Z _J10 / Z _J11 )) * I = (1+ (Z _B0 + Z ₁ * L ₁ ) / (Z _B1 + Z ₁ * I _B1 )) * I ............ (4) )formula

Further, the distance X ₂ from the branch point to the fault point is obtained by the above equation (5) using the branch point voltages / currents V _J1 , I _J1 and the positive phase impedance Z ₁ per unit length of the transmission line ( Computing means 14). Then, the distance (orientation value) X from the self-end to the accident point is obtained by the equation (6) (calculating means 15).

As described above, in the fault point localization when there is a branch power source, the back impedance of the self end and the branch power source end is used to obtain the branch point current. Here, normally, the self-power source is larger than the branch power source and has a great influence on the orientation result.
Therefore, a method for accurately determining the back impedance in real time using the voltage and current at the end is used. On the other hand, the branch power supply is generally small, so the back impedance is set. Strictly speaking, it fluctuates somewhat depending on the season and time zone, but setting an average value will not cause any practical problems.

Further, according to the present invention, since the impedance at the self-terminal is obtained from the change of the voltage / current at the self-terminal, it can be applied to a parallel two-line power transmission line. This is because the voltage / current of each of the two parallel lines changes depending on the type and point of the accident, but the impedance behind the self-end corresponding to the faulty line is calculated from the change in the voltage / current of the end, and the branch point required for orientation. This is because the current can be correctly estimated.

In the embodiment, the voltage V and the current I are measured by the distance between the lines and the impedance is measured by the positive phase in the case of the accident of two or more lines. This is a 2-wire short circuit, 2-wire ground fault, 3
Both the line short-circuit and the three-line ground fault measure the fault phase in the β circuit with the line voltage / current (β voltage / current and line voltage / current differ only in magnitude) and positive phase impedance (β amount impedance). Can be replaced with a positive phase impedance).

As described above, in one embodiment of the present invention, the branch point current is obtained by using the back impedance of the self end and the branch power supply end and the self end current, so that between the locator and the fault point. It is possible to provide a fault point locating device that can perform fault locating with high accuracy even if there is a branch power source. Another embodiment will be described below.

[1] In the above embodiment, in order to facilitate the explanation, the case where the branch power source / branch point is one and the accident point is beyond the branch point has been described. The present invention is not limited by the number of branch power sources / branch points or accident points, and can be easily expanded. FIG. 5 is a block diagram of another embodiment. In FIG. 5, P ₁ , P ₂ ,
P ₃ , P ₄ are branch power supplies, J ₁ , J ₂ , J ₃ are branch points, F
₁ , F ₂ , F ₃ , F ₄ are accident points, L ₁ , L ₂ , L ₃ , L
₄ is the line length of each section, X ₁ is the distance from the end to the fault point F ₁ , X ₂ , X ₃ , X ₄ are the branch points J ₁ , J ₂ , J ₃ to the fault points F ₂ , F ₃ , F _{4 is} the distance. 1-6
Since 8, P ₀ is the same as that in FIG. 1, its description is omitted. 7A
Is an arithmetic circuit, which will be described with reference to FIG. The branch power source is assumed to be directly under the transmission line, and the length of the branch line is an example. FIG. 6 is a block diagram illustrating the function of the arithmetic circuit 7A of FIG.

In FIG. 6, 11 and 12 have the same contents as in FIG. Reference numeral 20 is a setting means for setting and storing L _{1 to} L ₄ , Z ₁ , Z _{B1 to} Z _{B3 and the} like. L _{1 to} L ₄ are the same distances as in FIG. 5, Z ₁ is the same as in FIG. 2, Z _{B1 to} Z _B3 are branch power supplies P ₁ to
It is the positive phase impedance behind the P ₃ end. 21 performs the next operation of the operation means, and outputs the impedances Z _BD1 , Z _BD2 , Z _BD3 viewed from the end points from the respective branch points J ₁ , J ₂ , J ₃ . Z _B0 is a positive phase impedance behind the self-power source P ₀ , and Z _B1 and Z _B2 are positive phase impedances behind the branch power sources P ₁ and P ₂ . Here, ‖ indicates parallel operation, and is as follows, for example. Z _BD1 ‖Z _B1 = (Z _BD1 * Z _B1 ) / (Z _BD1 + Z _B1 ) ... (11) 22 is the calculating means for carrying out the following calculation, and the branch point current I _J1 ,
Outputs I _J2 and I _J3 . Z _B3 is the impedance behind the branch power supply P ₃ . Reference numeral 23 is a calculation means for performing the following calculation to calculate the branch point voltage V _J1 ,
Outputs V _J2 and V _J3 . Reference numeral 24 is a calculation means for carrying out the following calculation to obtain the distances X ₁ , X ₂ ,
Outputs X ₃ and X ₄ .

Reference numeral 25 is a comparison means for comparing the distances X1, X2, X3, X4 from the self-end or branch point to the accident point with the line lengths L1, L2, L3, L4 of each section. Numeral 26 is a calculation means for outputting the distance (localized value) from the self-end to the accident point. 27 is a gate element, which is the output or output C of the calculating means
(For example, out-of-section accident output) occurs. Specifically, it is as follows. When X ₁ ≦ L _1, the standard value X = X ₁ is output. When X ₁ > L ₁ Move to comparison of X ₂ and L ₂ . When X ₂ ≦ L _2, the standard value X = L ₁ + X ₂ is output. When X ₂ > L ₂ Move to comparison of X ₃ and L ₃ . The same applies hereinafter. When X ₄ > L ₄ , output C (outside section accident output) occurs.

As described in the other embodiments, even if there are a plurality of branch power sources, the branch point current can be obtained by using the positive-phase impedances at the end of the branch power source and at the back of the branch power source end. Can be oriented. Of course, the same applies when the number of branch power sources exceeds four.

[2] In the other embodiments described above, the length of the branch line is set to zero in order to facilitate the description. However, the present invention can be applied even when the length of the branch line is non-zero. The calculation means 21 in FIG. 6 may be modified as follows. Z _B1 → Z _B1 + Z ₁ * L _B1 etc. (L _B1 : Length between branch power supply P ₁ and branch point J ₁ )

[3] In the other embodiments described above, the impedances Z _{BD1 to} Z _BD3 , branch point currents I _{J1 to} I _J3 , branch point voltages V _{J1 to} V _J3 , the self end or It has been explained that the distances X _{1 to} X ₄ from each branch point to the accident point are calculated before the judgment by the comparison means 25. However, the present invention is not limited to this. For example, it may be as follows. X ₁ ≤ L
_{When 1} , Z _BD1 , I _J1 , V _J1 , and X ₂ are not calculated. When X ₁ > L ₁ , Z _BD1 , I _J1 , V _J1 , and X ₂ are calculated, and the comparison of X ₂ and L ₂ is started. (Same below)

[4] In the above embodiment, the case where only the branch power source is provided and there is no branch load has been described. However, the present invention can be applied to the case where there are both branch power supply and branch load. In the case of an accident with two or more lines, the effect of branch load on the accident current is extremely small and can be ignored. That is, information for identifying the branch power source or the branch load is set for each branch, the above is set for the branch power source, and the correction is not performed for the branch load. For example, when a load is connected to the branch point J ₂ , the following is performed.

[5] In the above zero, the β circuit has been described for an accident involving two or more lines. The present invention can also be applied in the case of a one-line accident (ground fault). When there is a one-line ground fault, distance measurement is performed with the α circuit and zero-phase circuit. That is, the voltage V / current I is the amount of α and the amount of zero phase, and the impedance is the amount of positive phase and zero phase. Voltage·
The conversion of each phase of the current into α and zero phase is performed by a known method.
Next, the positive-phase (zero-phase) impedance behind the self-end is obtained from the voltage / current corresponding to the change in the amount of α (zero-phase amount) (the impedance of α can be replaced by the positive-phase impedance). In this case, the above (1) to (5) are replaced with the following. However,
The accident phase is represented as a phase (the same applies to b and c phases).
The subscripts α and 0 represent the amount of α and the amount of zero phase, respectively. _{V J1 a = V J1 α +} V J10 = (Vα + V 0) -Z 1 * L 1 * Iα-Z 0 * L 1 * I 0 ......... (15) X ₂ = V _J1 a / (Z ₁ * I _J1 α + Z ₀ * I _J10 ) ... (19)

Here, Z _B01 , Z _B11 , Z _B00 ,
Z _B10 and Z ₀ are a positive phase impedance behind its own end, a positive phase impedance of the branch power source P ₁ end, a zero phase impedance behind its own end, a zero phase impedance of the branch power source P ₁ end, respectively.
Zero-phase impedance per unit length of transmission line is shown. As described above, the present invention can be applied by using the α amount and the zero phase amount even in the case of the one-line ground fault.

[6] In the above example, the background impedance is described as the resistance component + reactance component. However, in practice, only the reactance component may be used. This is because the reactance component for the positive phase component is significantly larger than the resistance component for both the power supply and the transmission line. Since this approximation holds well, the number of settings can be reduced by the setting means, and the apparatus can be simplified.

[0032]

As described above, according to the present invention, the back impedance of the self-end (the end at which the orientation device is installed), which has a particularly large power supply capacity and is dominant in the fault current, is accurately obtained from the voltage-current information of the self-end. Since the branch point current is calculated almost correctly by using the set impedance of the branch power source and the self-end current, even if there is a branch power source between the fault point and the locator, its influence can be eliminated. Further, it is possible to provide a highly accurate fault point locating device which can be applied to a parallel two-line power transmission line.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a part of FIG. 1 in detail.

FIG. 3 is a diagram for explaining the operation of FIG.

FIG. 4 is a diagram for explaining the operation of FIG.

FIG. 5 is a configuration diagram of another embodiment of the present invention.

FIG. 6 is a block diagram illustrating a part of FIG. 5 in detail.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmission line 2 Transformer 3 Current transformer 4,5 Input converter 6 Analog-digital converter 7, 7A Arithmetic circuit 8 Display circuit 9 Setting means 10-15, 21-24, 26 Arithmetic means 25 Comparing means 27 Gate element

Claims (2)

[Claims] 1. In a fault point locating device for locating a fault point of a transmission line having a branch, a first means for reading a voltage / current at the self-end, a line impedance per unit length, a self-end and between each branch. Second means for reading the line length and the set value of the impedance behind the power source of each branch, a third means for calculating the branch point voltage using the outputs of the first and second means, and a first means. Means for calculating the changed voltage / current from the output of the second means, fifth means for calculating the impedance behind the self-end from the output of the fourth means, and outputs of the first, second, and fifth means From the output of the second, third, and sixth means, and seventh means for calculating the distance from the self-end to the fault point. Failure point locator. 2. In the fault point locating device according to claim 1, instead of the third, sixth and seventh means, the impedance of the self-end side from the branch point is calculated from the outputs of the second and fifth means. 8th means for calculating the branch point current from the outputs of the 1st, 2nd, 8th means, and 9th means for calculating the branch point voltage from the outputs of the 2nd, 8th, 9th means Tenth means of doing
An eleventh means for calculating the distance from the self-end to the accident point based on the outputs of the second, ninth, and tenth means.