JP2637074B2 - Transmission line fault point location method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for locating a fault in a transmission line having a branch load.

[Technical background of the invention and its problems]

Conventionally, there are a surge receiving method, a pulse radar method, an impedance measuring method, and the like as a fault locating method of a transmission line. The former two require expensive communication equipment or signal coupling equipment to transmission lines.

On the other hand, the latter impedance measurement method is based on the voltage and current obtained from the voltage transformer and the AC converter, and does not require new equipment to obtain the input amount. For this reason, recently, an impedance measurement method has received particular attention, and for example, Japanese Patent Publication No. 58-29471, "Accident Point Determination Method" has been proposed.

The conventional impedance measurement system including the invention of Japanese Patent Publication No. 58-29471 presupposes that the transmission line has no branch. If there is a branch, it is assumed that the orientation is up to the branch point. This does not cause any problem for the backbone transmission line. Also, even if there is a branch, the number of installations does not increase significantly even if the apparatus is set for each branch because it is extremely limited. However, lower-level transmission lines, such as 66KV, have a lot of service to customers, and it is difficult to install equipment at each service point economically and in terms of operation.

[Object of the invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fault point locating method (method and apparatus thereof) which is not affected by a branch load in a transmission line having many branches. .

[Summary of the Invention]

In summary, the impedance measurement type fault point locating method is a method of calculating a distance by dividing a voltage drop from a self end to a fault point by a voltage drop per unit length of the transmission line.
In a transmission line with a branch, the current differs depending on the section, so that the voltage drop per unit length differs. Therefore, the present invention provides a fault point locating method for locating a fault point of a transmission line having a branch, wherein a load current obtained from a measured value of a line current of a healthy phase at a transmission end (own end) of the transmission line is determined by a ratio of a set value. By estimating the current of each branch load, sequentially subtracting the estimated value from the measured value of the faulty current at the sending end and treating it as the current in each section, and calculating the voltage drop per unit length in each section. The correct distance is to be calculated. As the set value, for example, an assumed demand power of each branch load or the like is used.

(Example of the invention)

FIG. 1 is a configuration diagram showing hardware of one embodiment of the present invention. 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-to-digital conversion circuit (hereinafter referred to as an AD conversion circuit), 7 is an arithmetic circuit,
8 display circuit, L ₁ ~L ₄ branch load or end load (referred to collectively branched load following.), F ₁ ~F ₄ fault point, l ₁ to l ₄
The distance of each segment, x ₁ ~x ₄ is a distance fault point from Zidane or each branch point, V is Zidane voltage, I is a Zidane current.
Unless confusion, for example 3-phase voltages V _a, V _b, V on behalf of the V _c, 3-phase currents I _a, is represented by I _b, on behalf I _c I. Note fault point F ₁ to F _4, it is assumed that actually failed only any one point of this is occurring.

The input conversion circuit 4 converts the output of the transformer 2 to an appropriate level and generates an output through a pre-filter for removing high frequency components. This is a commonly used method and does not particularly show an internal configuration diagram. Similarly, the input conversion circuit 5 converts the secondary current of the current transformer 3 to an appropriate voltage level and generates an output through a pre-filter. AD conversion circuit 6
Samples the input at regular intervals, performs AD conversion, and inputs the digital output to the arithmetic circuit 7. Such an internal configuration of the AD conversion circuit 6 is also a well-known technique, and the configuration diagram is omitted.

The arithmetic circuit 7 executes the arithmetic operation described later 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 will be described without distinction from the own-end voltage V and the own-end current I unless there is a possibility of confusion. These usages are commonly used. Further, the digital output converted by the AD conversion circuit 6 is represented by V and I unless there is confusion.
Further, the branch loads L _{1 to} L ₄ are usually located immediately below the transmission line 1 or at a very short distance, and the distance after the branch is not particularly considered.

FIG. 2 is a block diagram for explaining the function of the arithmetic circuit 7 of FIG. The present invention is intended for frequent single-line ground faults, and the a-phase ground fault will be described below.
Regarding the other-phase ground fault, the same operation as in the case of the a-phase ground fault is performed on the basis of the ground fault phase in the same manner as the normal method.

In FIG. 2, reference numeral 9 denotes setting means, which are constants Z _α , Z ₀ , l ₁
~l _4, K ₁ ~K ₄ or the like is set is stored. Z _α and Z
₀ are each α mode and O-mode impedance of the transmission line per unit length, l ₁ to l ₄ is the distance of the first figure and similarly each section, K ₁
~K ₄ is a constant for each branch loads. As the constants K _{1 to} K ₄ , for example, the installed capacity of each branch load or an assumed value of substantial maximum power is used.

Numeral 10 denotes arithmetic means for executing the following arithmetic operation by inputting the voltage V, the current I, the constant Z _α , and Z ₀ to obtain the voltage / current product J _V , the unit long voltage drop current product J _I and the load voltage drop current. Outputs the product J _L.

_{J V = I m (V a} I D *), J I = I m (Z α I α + Z 0 I 0), J L = I m (Z α I β <90 ° · I _D ^*) I _D = [value in the failure of I _α] fault component current = - [pre-tide value of I ^{_α] *:} complex conjugate These calculations are well known as described in JP-B-58-29471. Numeral 11 denotes arithmetic means for performing the following arithmetic operations and outputting outputs G ₁ , G ₂ and G ₃ .

G ₁ = K ₁ / K _T , G ₂ = K ₂ / K _T , G ₃ = K ₃ / K _T , K _T = K ₁ + K ₂ + K ₃ + K ₄ …
(2) 12 produces output x _i to perform the following operations by the arithmetic means.

First, the arithmetic unit 13 and the input x and the input l ₁ is the J _V / J _I = x runs comparing means 14 are compared by, caused the output A if xl ₁ gate element 15 through the x is x _i ( i =
Output as 1). If x> l ₁ produce output B calculation unit 13 divides the second set. The second set is arithmetic means
The output of 16 and 17, that is, J _V -l ₁ J _I and J _I -G ₁ J _L, is executed _{(J V -l 1 J I)} / (J I -G 1 J L) = x, in the same manner as explained above is output as if _{xl 2 x i (i = 2} ), moves to the third set if x> l _2. The third set is the output of the arithmetic means 18 and 19, and similarly, ｛J _V −l ₁ J _I −l
_{2 (J I -G 1 J L} )} / (J I -G 1 J L -G 2 J L) = x is executed, is output as x _{i (i} = 3) if xl _3, x>
If l ₃ moves to a fourth set. The fourth set is the output of the arithmetic means 20 and 21, and is similar to that described above, where ΔJ _V −l ₁ J _I −l
₂ (J _I −G ₁ J _L ) −l ₃ (J _I −G ₁ J _L −G ₂ J _L )｝ / (J _I −G ₁ J _L
−G ₂ J _L −G ₃ J _L ) = x is executed. If x ₄ , x _i (i
= 4) is output as, if x> l _4, produce an output C from the comparator 14. The output C is displayed by the display circuit 8 in FIG. 1, for example, as an out-of-section failure.

FIG. 3 is an equivalent circuit diagram for explaining the operation of FIG. In Figure 3, also serves as a review of known content so as to facilitate the understanding Before describing the general operation of the second view is shown an equivalent circuit diagram for limiting the fault point F _1. That figure represents an equivalent circuit of a phase 1 line ground fault, where V _s is the supply voltage, Z _{alpha B} and Z _0B are α mode and 0 mode impedance behind Zidane, Z _0T the terminal loads behind , V _F is the fault point voltage, I _0F and I _0T are the zero-phase currents from the fault point and the terminal side, respectively. This is a view in _{V a = V α + V 0} = x 1 Z α I α + x 1 Z 0 I 0 + V F ... (3), I is the fault component current I _D of the above-described approximately by phase with the fault point voltage ^{_{m (V F I D *)}} ≒ 0 ... since a _{(4) J V = I m} (V a I D *) ≒ I m {(x 1 Z α I α + x 1 Z 0 I 0) I D * ｝ = X ₁ J _I ∴x ₁ ≒ J _V / J _I (5) As described above, it is explained that the function of the arithmetic circuit in FIG. 2 when the fault point is in the first section is correct.

4 and 5 are equivalent circuit diagrams for explaining the operation of FIG. In this figure shows the same manner as described above equivalent circuit diagram in the case in the fault point F ₄ clogging fourth section. Since easily analogized also when the fault point F ₂ or F _3, and general description drives out described in the case of F _4. In the figure, I _L α ₁ ,
I _L α ₂ and I _L α ₃ are α mode currents of the respective branch loads. It is well known that a branch load other than a terminal load is normally ungrounded, and an equivalent circuit as shown in FIG. The following equation is obtained from this equivalent circuit.

V _a = V _α + V ₀ = l ₁ (Z _α I _α + Z ₀ I ₀ ) + l ₂ ｛Z _α (I _α -I _L α ₁ ) + Z ₀ I ₀ ｝ + l ₃ ｛Z _α (I _α -I _L α ₁ −I _L α ₂ ) + Z ₀ I ₀ ｝ + x ₄ ｛Z _α (I _α −I _L α ₁ −I _L α ₂ −I _L α ₃ ) + Z ₀ I ₀ ｝ + V _F (1) As is well known, the β-mode current at the time of a line ground fault is not affected by the accident mode, so that the α-mode load current at the time of the accident can be calculated from this current. That is, the β mode current to each load in FIG. 5 is equal in magnitude to the α mode load current, and the phase is delayed by 90 °. Therefore Becomes

As far as the distribution ratio of the branch load is concerned, the line impedance l _{1 Zα and the} like can be omitted, so the following equation is obtained from the equation (2).

_{I L α i = G i I} β <90 °, (i = 1~n-1) ... (7) where G _i is the power factor of each branch loads the approximately equal, and approximately real Become. Such an approximation is extremely effective, and will be described under the conditions.

 The following equation is obtained from the equation (7).

Thus (1), (6), (8) and ^{_{I m (V F I D *}} ) ≒
The following equation is obtained from 0.

J _V ≒ l ₁ J _I + l ₂ (J _I -G ₁ J _L ) + l ₃ (J _I -G ₁ J _L -G ₂ J _L ) + x ₄ (J _I -G ₁ J _L -G ₂ J _L- G ₃ J _L )… (9) ∴x ₄ = ｛J _V −l ₁ J _I −l ₂ (J _I −G ₁ J _L ) −l ₃ (J _I −G ₁ J _L −G ₂
J _L )｝ / ｛J _I -G ₁ J _L -G ₂ J _L -G ₃ J _L … (10) The operation of FIG. 2 has been described above.

This embodiment as described above, the power factor of each branch loads as a approximately equal, as the set value of the assumed value or the like of the maximum power, distributed by the sum I _beta <90゜Wo ratio of the set of branch load power Each branch load current was estimated, and the current in each section of the transmission line was calculated using this to eliminate the effects of the branch load.

This method has an advantage that there is no influence of a zero-phase circuit because a branch load current is assumed by using a β-mode current.

〔The invention's effect〕

As described above, according to the present invention, the fault point is located by obtaining the sum of the branch load currents from the self-end healthy interphase current (healthy line current) and estimating each branch load current from this and the distribution ratio based on the set value. Therefore, the influence of the branch load can be eliminated. Also, this set value may be based on only the distribution ratio of the active component power or the distribution ratio of the reactive component power, but since the line voltage drop is omitted approximately, it may be considered as the current distribution ratio. Good.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a block diagram for explaining a part of FIG. 1 in detail, and FIGS. 3 to 5 are diagrams for explaining the operation of FIG. It is an equivalent circuit diagram. DESCRIPTION OF SYMBOLS 1 ... Transmission line 2 ... Transformer 3 ... Current transformer 4,5 ... Input conversion circuit 6 ... Analog digital conversion circuit 7 ... Calculation circuit 8 ... Display circuit 9 ... Setting means 10 ~ 13,16 ~ 21 Calculation means 14 Comparison means 15, Gate element

Claims (4)

(57) [Claims] In a fault point locating method for locating a fault point of a transmission line having a branch, a distribution ratio is set in advance for a branch load, and in the event of a one-line ground fault, the fault phase of the self-terminal current is determined. The load current at the time of an accident is calculated using the other two-phase line currents that are not involved, the load current flowing through the branch load is calculated using the calculated value in accordance with the distribution ratio, and the branch load current is calculated as the local end current. A method of locating a fault point using a value obtained by subtracting the measured value from the measured value and a measured value of the own terminal voltage. 2. A transmission line fault point locating method according to claim 1, wherein said distribution ratio is an assumed distribution ratio of branch load power. 3. A fault point locating apparatus for locating a fault point of a single-line ground fault in a transmission line having a branch, comprising: setting means for storing in advance a distribution ratio for each branch load; Provision of a location calculation means for locating a fault point using a value obtained by subtracting a load current flowing through a branch load obtained from a line current of a terminal healthy phase from a measured value of the own terminal current and a measured value of the own terminal voltage. Transmission line fault point locating device characterized by the above-mentioned. 4. A transmission line fault point locating system of patents recited claims third term of the orientation calculation unit, local end current and voltage current product weight from Zidane voltage J _V and unit length voltage drop current tonnage first calculating means as well as calculating the J _I calculates a load-related voltage drop current tonnage J _L from the line current of the local end healthy phase, from the voltage current tonnage J _V until the branch section earlier sections A second calculating means for subtracting the line drop voltage amount; and a branch load current amount up to the section before the branch section obtained from the load voltage drop current product amount J _L and the distribution ratio, and the unit length voltage drop current product. a third calculation means for subtracting from the amount J _I, and fourth calculating means for calculating an orientation value is divided by the operation output of the third computing means computing an output of said second arithmetic means, the orientation If the value does not exceed the branch section distance, output this orientation value, Wherein in the next branch section when the orientation value exceeds the branch section distance second, third and fourth
And a comparing means for executing the calculating means.