JPH0782063B2 - Failure point locator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a parallel two-line three-terminal transmission line system having a branch, in which a faulty branch point can be identified. The present invention relates to an orientation device.

(Prior Art) Conventionally, as a fault point locating method for a transmission line system, a method using a traveling liquid such as a surge receiving method or a pulse radar method and a fault point by measuring the voltage and current of the transmission line are identified. There is an impedance measurement method for locating or a zero-phase current comparison method for locating a fault point based on the ratio of the magnitude of zero-phase current in each line of a parallel two-line transmission line system. In this case, the former two require new expensive communication equipment or signal coupling equipment to the transmission line, whereas the latter impedance measurement method and zero-phase current comparison method require voltage transformers and current transformers. Since the fault point is located by the obtained voltage and current, no new equipment is needed to obtain the input amount.
Therefore, recently, a fault point locating method for a transmission line system, which uses an impedance measuring method and a zero-phase current comparison method, has been particularly noticed. As an example of this type of fault location system, Japanese Patent Application No. 59-59578 (Japanese Patent Application Laid-Open No. 60-204220) "Transmission line fault location system" is also used in the impedance measurement system. Japanese Patent Application Sho 59
-218202 (JP-A-61-98119) "Fault location device"
Etc. have been proposed.

FIG. 3 is a block diagram showing the hardware of the transmission line fault location system. In FIG. 3, 101 is a target transmission line, 102 is a transformer, 103 is a current transformer, 104 and 105 are input conversion circuits, 106 is an analog-digital conversion circuit (hereinafter referred to as an A / D conversion circuit), 107 is an arithmetic circuit, 108 is a display circuit, L ₁
~ L ₄ is a branch load or end load (hereinafter collectively referred to as branch load), F1 to F4 are fault points, I1 to I4 are distances in each section, x _{1 to} x ₄ are from the own terminal or each branch point The distance to the failure point, V is the self-terminal voltage, and I is the self-terminal current. In addition,
Unless confused, the three-phase voltages V _a , V _b , and V _c are represented by V, and the three-phase currents I _a , I _b , and I _c are represented by I. Further, it is assumed that the failure points F _{1 to} F ₄ occur at only one of them.

The input conversion circuit 104 converts the output of the transformer 102 to an appropriate level, and further produces an output through a prefilter for removing high frequency components. These are the methods that are usually used, and no internal block diagram is shown. The input conversion circuit 105 also has substantially the same circuit configuration, and the input converter circuit 105 has two circuits
The next current is converted to an appropriate voltage level and is output through a prefilter. The A / D conversion circuit 106 samples the input at regular intervals, A / D converts the digital output, and outputs the digital output to the arithmetic circuit 107.
Output to. Such an internal configuration of the A / D conversion circuit 106 is also a well-known technique, and its configuration diagram is omitted.

The arithmetic circuit 107 executes the arithmetic operation described later with reference to FIG. 4, and the result is displayed by the display circuit 108.

Here, the outputs of the input conversion circuits 104 and 105 will be described without being distinguished from the own terminal voltage V and the own terminal current I unless there is a risk of confusion. These usages are commonly used. Further, the digital output converted by the A / D conversion circuit 106 is also represented by V and I unless there is any confusion. In addition, the branch loads L _{1 to} L ₄ are usually immediately below or very close to the power transmission line 101, and the distance after the branch is not particularly considered.

Next, the function of the arithmetic circuit 107 of FIG. 3 will be described with reference to the functional block diagram of FIG. Although the a-phase 1-line ground fault will be described here, it is the same as the normal method for the ground faults of other phases to perform the same calculation as in the case of the a-phase ground fault with reference to the ground fault phase. Is.

In FIG. 4, 109 is a setting means, which is a constant Zα, Z0, I.
1 to I4, K1 to K4, etc. are set and stored. Where Z
_α and Z ₀ are the α mode and 0 mode impedance per unit length of the transmission line, I _{1 to} I ₄ are the distances of each section as in FIG. 3, and the constants K _{1 to} K ₄ are constants for each branch load. As the constants K _{1 to} K ₄ , for example, the installed capacity of each branch load or an assumed value of the actual maximum power is used.

Reference numeral 110 denotes an arithmetic means, which receives the voltage V, the current I, the constants Z _α and Z ₀ as input, performs the following arithmetic operations, and outputs the outputs J _V , J _I , and J _L.

^{_{Jv = Im (VaI D *)}} , J I = I m {(Z α I α + Z 0 I 0) I D *} J L = I m {Z α (I α -2I 0) I D *} I D = [Fault current] = [value of I _α during fault]-[pre-flow value of I _α ] *: conjugate complex number Reference numeral 111 denotes a calculation means, which receives the integers K _{1 to} K ₄ as input, performs the following calculation, and outputs 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) 112 is a calculation means and calculation Output from means 110 J _V , J _I , J _L
The outputs G ₁ , G ₂ , and G ₃ from the calculation means 111 are input, the following calculation is performed, and the output x ₁ is transmitted.

First, J _V / J _I = x by computing means 113 have up for the first set is executed, the input x by the following comparison means 114 and the input I ₁ are compared, result in output A if xI ₁ , Gate element 11
Through x, this x is output as x _i (i = 1). If x> I ₁ , the output B is generated, and the calculation means 113 outputs the second
Move to the group. In the second set, the ratio output from the arithmetic unit 116 and 117, that is, from J _V -I1JI and JI-G1JL (JV-
_{I 1 J I) / (J} I -G 1 J L) = x is executed, is output as if xI ₂ in the same manner as described above _{x i (i = 2),} x> I 2
If so, move to the third group. In the third group, the calculation means 118
And the output from 119, namely {J _V −I ₁ J ₁ −I ₂ (J ₁ −G
₁ J _L )}-and (J ₁ −G ₁ J _L −G ₂ J _L ), the ratio {J _V −I
₁ J ₁ −I ₂ (J ₁ −G ₁ J _L )} / (J ₁ −G ₁ J _L −G ₂ J _L ) = x is executed, and if xI ₃ then x _i (i = 3) Is output,
If x> I ₃ , move to the fourth group. The fourth set is a calculation means.
From the outputs of 120 and 121, the output ratio is (J _V −I ₁ J ₁ −I ₂ (J ₁ −G ₁ J _L ) −I 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 xI ₄ , it is output as x _i (i = 4), and if x> I ₄ , an output C is generated from the comparison means 114. This output C
Is displayed as an out-of-section failure by the display circuit 108 in FIG.

FIG. 5 is an equivalent circuit diagram for explaining the operation of FIG. Note that FIG. 5 shows an equivalent circuit diagram in which the failure point is limited to F ₁ in order to facilitate understanding before explaining the general operation of FIG. That is, the figure shows an equivalent circuit of an a-phase 1-line ground fault, where V _S is the power supply voltage, z _αB and Z _0B are the α-mode and 0-mode impedance behind its own terminal, and VF is the fault point. Since the voltage and other symbols have been previously described, the description thereof will be omitted. In FIG. 5, V _a = V _α + V ₀ = x ₁ Z _α I _α + x ₁ Z ₀ I ₀ + V _F (3), and the above-mentioned fault current I _D is approximately the fault voltage. In the same phase, I _m = (V _F I _D ^* ) ≈0 (4), so J _V = I _m (V _a I _D ^* ) ≈I _m {(x ₁ Z _α I _α + x ₁ Z ₀ I ₀ ) _ID ^* ) = x ₁ J _I ∴x ₁ ≈ J _V / J _I (5) As described above, the function of the arithmetic circuit in FIG. 3 when the failure point is in the first section Is explained to be correct.

FIG. 6 is an equivalent circuit diagram for explaining the operation of FIG. Note that FIG. 6 shows an equivalent circuit diagram similar to the above when the failure point is in F _4, that is, in the fourth section.
Since it can be easily inferred even when the failure point is F ₂ or F ₃ , here, a general description will be given with the description of the case of F ₄ .

In the figure, I _Lα1 , I _Lα2 , I _Lα3 are α-mode currents of the respective branch loads. If each branch load is ungrounded,
It is well known that an equivalent circuit as shown in FIG. The following equation is obtained from this equivalent circuit.

V _a = V _α + V ₀ = I ₁ (Z _α I _α + Z ₀ I ₀ ) + I ₂ {Z _α (I _α + I _{Lα 1} ) + Z ₀ I ₀ + I ₃ {Z _α (I _α −I _{Lα 1} −I _{Lα 2} ) _{+ Z 0 I 0 +} x} 4 {Z α (I α -I Lα1 -I Lα2 - Lα3) + Z 0 I 0) If V _F ...... (6) each branch loads are ungrounded, failure point 0 mode current I _0F
Is equal to the self-terminal 0 mode current I ₀ , and Σ _ILα1 = I _α −2I
It becomes ₀ . Since the line impedance I ₁ Z _{α and the} like can be omitted as far as the distribution ratio of the branch load is concerned, the following equation is obtained from the equation (2).

I _Lα1 = G _i (I _α −2I ₀ ), (i = 1 to n−1) (7) Here, if G _i is that the power factor of each branch load is substantially equal,
Approximately a real number. Such an approximation is extremely effective and will be described below under the conditions.

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

I _m (Z _a I _Lα1 I _D ^* ) = G _i I _m {Z _α (I _α −2I ₀ ) I _D ^* } = G _i J _L (8) Therefore, the above (1) and (6) The following expression is obtained from the expression (8) and I _m (V _{F ID} ^* ) ≈0.

J _V ≈ I ₁ J _I + I ₂ (J _I −G ₁ J _L ) + I 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) With the configuration as described above, it is possible to locate a failure point even in a transmission line system having a branch.

Next, the "fault point locating device" disclosed in the above-mentioned Japanese Patent Application No. 59-218202 will be described with reference to FIGS. 7 to 14.

FIG. 7 shows a two-line power transmission line 201 that is branched from a high-resistance grounding system and laid in parallel, and a current transformer that is connected to each line of the power transmission line 201 and measures an alternating current flowing through the power transmission line 201. 203, zero-phase current converters 205a and 205b connected to the secondary winding of the current transformer 203 to detect a zero-phase current, and a voltage connected to a high resistance ground system to measure the AC voltage of the system. The transformer 202 and the zero-phase voltage connected to the voltage transformer 202,
A voltage converter 205c that detects a phase voltage or a line voltage, a failure detection unit 206 that is connected to the voltage converter 205c and that determines a one-line ground fault or a failure phase, and a voltage converter 205c.
And an active current extraction circuit 20 that is connected to the zero-phase current converters 205a and 205b and extracts the active component current included in the zero-phase current.
7 shows a fault point locating device including 7a and 207b and a location calculation circuit 208 that is connected to the active current extraction circuits 207a and 207b and locates a fault point.

That is, in FIG. 7, 201 is the target transmission line, 202 is a voltage transformer that measures the voltage of the grid, 203 is a current transformer that measures the current of the transmission line, and 204 is the main part of this device. 2
Reference numeral 05c is a voltage converter that converts the system voltage into a value that is easy to use, and 205a and 205b are zero-phase current converters that output a zero-phase current component. Here, the output of the voltage converter 205c is the zero-phase voltage and the voltage components between each phase and each line. Reference numeral 206 denotes a system fault detection unit that discriminates a one-line ground fault or discriminates a fault phase. 207a and 207b are active current extraction circuits that extract the active component current included in the zero-phase current.For this active component current extraction, the zero-phase voltage is used as the polarity Vpol and the fault phase is identified by the fault phase. There is a method of using a line voltage which is a quadrature voltage (for example, a bc phase voltage in the case of a phase failure). Either method may be used, but the effective voltage current is extracted using the line voltage by the failed phase identification as the polarity amount. By doing so, the orientation accuracy is improved without being influenced by the configuration of the zero-phase circuit. 208 is an orientation calculation circuit, and 209 is an output circuit that outputs the orientation result.

First, a method of finding a failure point by a ratio of magnitudes of zero-phase currents when a one-line ground fault occurs in two parallel lines of a high resistance system will be described.

When a one-line ground fault occurs at point F in Fig. 8, the transmission line length is l, the distance from terminal A to fault point F is xl, and the zero-phase self and mutual impedance per unit length of the line are Z. ₀ , Z _m , the zero-phase current flowing on the faulty line side and the sound line side is I ₀₁ , I ₀₂ ,
_Assuming that the zero-phase voltage at the terminal A and the fault point F is V _0A and V _0F , V _0A = I ₀₁ Z ₀ xl + I ₀₂ Z _m xl + V _0F on the fault line side (11) and V _0A on the healthy circuit side = I ₀₂ Z ₀ (2-x) l + I ₀₁ Z _m xl −2I ₀₂ Z _m (1-x) l + V _0F ...... (12) holds, respectively.

Eliminating V _0A and V _0F from the equations (11) and (12), I ₀₁ xl (Z ₀ −Z _m ) −I ₀₂ l (Z ₀ −Z _m ) = I ₀₂ (1-x) l ( Z ₀ −Z _m ), Z ₀ −Z _m ≠ 0, and Is represented as Therefore, the ratio x of the distance to the fault point to the entire length can be obtained only by the zero-phase current of each line regardless of the magnitude of the line impedance.

Next, if there is a cable system or the like behind the opposite terminal, a zero-phase current will flow from behind the opposite terminal at the time of a one-line ground fault, and the orientation accuracy will be significantly impaired. This point will be described with reference to FIG. In FIG. 9, the zero-phase current flowing from the terminal B is I0B (I
It is the same as FIG. 8 except that it is 03).

In FIG. 9, V _0A = I ₀₁ Z ₀ xl + I ₀₂ Z _m xl + V _0F (14) V _0A = I ₀₂ Z ₀ l + (I ₀₂ + I ₀₃ ) Z ₀ (1-x) l + I ₀₁ Z _m xl- I ₀₂ Z _m (1-x) l − (I ₀₂ + I ₀₃ ) Z _m (1-x) l + V _0F …… (15) From these equations (14) and (15), I ₀₁ xl (Z ₀ −Z _m) -I ₀₂ from _{(Z 0 -Z m) l =} (I 02 + I 03) (Z 0 -Z m) (1-X) l ...... (16), Becomes

Next, the orientation calculation with the effective component of the zero-phase current of each line will be described.

To summarize the terms of the ninth indicating the current relationship in FIG. (16) than I _0B to the right side, the _{(01 + 02) xl-2} 02 l = 03 (1-x) l ...... (18). Now, when the effective component for the polarity amount V _{pol is calculated} on both sides, Re [V _pol {( ₀₁ + ₀₂ ) xl-2 ₀₂ l}] = Re [▲ ^* _pol ▼ I ₀₃ (1-x) l] ...... (19) However, Re [] indicates the effective amount within [].

▲ ^* _pol ▼ is the conjugate complex number component of _pol .

If I _0B is a charge current or reactor current, the right side of equation (19) is 0.

Therefore, from the _{^{Re [▲ * pol ▼ {(}} 01 + 02) xl-2 02 l}] = 0, Therefore, the influence of I _0B can be removed. The orientation calculation circuit 8 shown in FIG. 7 performs the calculation of the equation (20).

In the example of FIG. 7 to FIG. 9, the counter terminal does not have NGR. However, even when the counter terminal also has NGR, the effective component can be used for orientation. That is, the zero-phase voltage of the other terminal with NGR behind is found from the amount of electricity obtained from the measurement terminal, and the inflow current from NGR is calculated and determined by this, and the method is as follows. .

Now, it is assumed that the current at 100% ground fault from the NGR of the opposite terminal is I _RB , the zero-phase voltage generated at the ground fault at its own terminal is V _0A , or the ground fault occurrence rate is η _A. Figure 10 shows an example of a system with NGR at the opposite terminal. Similar to Fig. 9, the current relationship is (18)
As shown in the formula, I _0B is V _0A , η _A , I ₀₂ and 100% NGR current I
_{From RB} , It is represented by. Therefore, from the _{^{Re [▲ V * pol ▼ {}} (01 + 02) xl-2 02 l -I 03 (1-x) l}] = 0, Required by.

In addition, even in a three-terminal system, it is possible to perform orientation based on the effective component. That is, in FIG. 11 and FIG. 12, I ₀₁ −I ₀₂
And by the ratio of _{I 0A + I 0B + I 0C} , or a failure occurring in the line l _a, can distinguish whether the failure occurring in the line l _b or l _c, line
In the case of a fault occurring at l _a , it can be expressed by the ratio from the point A to the branch point by converting x ′ in the following equation in FIG.

x = x ′ × (la + lblc) / l _{a The} above equation is Is in the range.

That is, Then, the failure occurs in l _b or l _c .

Taking this effective amount, And is calculated by calculating this formula. l _b
Since the failure that occurred in 1 _c cannot be distinguished from the failure that occurred in l _c , two cases, that is, the failure that occurred in l _b and the failure that occurred in l _c will be obtained. Ratio l _b from B terminal to the fault point is calculated by the following equation.

x = (1-X ′) × (lalc + lb) / lb Taking this effective amount, The ratio of lc from the C terminal to the failure point is _calculated by the following formula.

x = (1−X ′) × (l _a l _b + l _c ) / l _{c If} this effective part is taken, By the way, in this case, when considering a parallel two-line three-terminal transmission line system as the transmission line system to be oriented, if the failure point is within the branch point, only one orientation effect is required, and there is no problem. . However, if the failure point is beyond the branch point, the orientation result is obtained for each of the two branch lines, but it is difficult to determine which branch line has the failure.

(Problems to be Solved by the Invention) As described above, the conventional fault point locating device has a problem that it is not possible to determine a fault branch line in a parallel two-line three-terminal transmission line system having a branch. It was

The present invention has been made to solve the above problems, and its purpose is to provide a distance to a failure point by using only the voltage and current value at its own terminal even when a failure occurs beyond the branch point. Another object of the present invention is to provide a fault point locating device capable of determining and determining a fault branch line.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above-mentioned object, a fault point locating device according to the present invention is provided with a predetermined one terminal in a parallel two-line three-terminal transmission line system having a branch. Using the measured voltage value, the active component currents contained in the zero-phase currents of the faulty line and the healthy line are extracted, respectively, and the fault point is located based on the ratio of the magnitudes of the extracted zero-phase active component currents. A first failure point locating means,
An assumed distribution ratio of the branch load power is set, the branch load current flowing in the branch load is obtained from the set value and the measured current value of the predetermined one terminal, and the branch load current and the predetermined one terminal are calculated. A line voltage drop due to a fault current is obtained using a difference from the measured current value and the measured voltage value of the predetermined one terminal, and a fault point is located based on the line voltage drop.
The fault point locating means and the deciding means for comparing the locating result by the first fault point locating means and the locating result by the second fault point locating means and determining the fault branch line based on the comparison result. It is characterized in that it is equipped with.

(Operation) In the fault location device described above, the parallel 2
Using the measured voltage value of one terminal in the three-terminal transmission line system of the line, the first fault point locating means locates the fault point based on the ratio of the zero-phase effective component currents of the fault line and the sound line, and A branch load current is obtained from the assumed distribution ratio set value of the branch load power and the measured current value of the one terminal by the second fault point locating means, and the difference between the branch load current and the measured current value of the one terminal. Also, the line voltage drop due to the fault current is obtained by using the measured voltage value at the one terminal, and the fault point is located based on this line voltage drop. And finally,
The determination means determines the fault branch line based on the comparison result of the orientation results by the respective fault point orientation means.

(Embodiment) The present invention is a parallel two-line three-terminal transmission line system having a branch, a zero-phase current comparison method for locating a fault point based on the ratio of the magnitude of the zero-phase current of each line, and a line voltage, By combining the impedance measurement method that measures the current and locates the fault point by the line voltage drop due to the fault current, the branch line in which the fault occurs is determined.

An embodiment of the present invention based on the above concept will be described below with reference to the drawings.

FIG. 1 is a diagram showing a hardware configuration example of a fault point locating device according to the present invention. In Fig. 1, 1 is a transmission line of a parallel 2-line 3-terminal system that is the object of orientation, 2 is a transformer that measures the voltage of its own terminal, 3 is a current transformer that also measures current, and 4 and 5 are this transformer. Input conversion circuit which receives the outputs from the transformer 2 and the current transformer 3, and 6 each input conversion circuit
An analog / digital conversion circuit (hereinafter referred to as an A / D conversion circuit) that receives the outputs from 4,5, 7 is an arithmetic circuit that receives the output from the A / D conversion circuit 6, and 8 is an output circuit Is. Further, L _B and L _C are branch loads, l _A , l _B , l _C are distances from terminal A, terminal B, terminal C to branch point J, V is own terminal voltage, and I ₁ and I ₂ are own Terminal current, F _A , F _B , F _C are fault points, x _A ,
x _B and x _C are the distances from the self terminal to each failure point. In addition, it is assumed that the failure points F _A , F _B , and F _C occur at only one of them.

That is, in FIG. 1, the input conversion circuit 4 is the transformer 2
The output from the above is converted to an appropriate level, and the output is generated through a prefilter for removing high frequency components. Similarly, the input conversion circuit 5 also converts the secondary current from the current transformer 3 into an appropriate voltage level and produces an output through a prefilter. The A / D conversion circuit 6 samples the input at regular intervals, performs A / D conversion, and outputs a digital output to the arithmetic circuit 7. Further, the arithmetic circuit 7 carries out an arithmetic operation described later, and the result is outputted by the output circuit 8.

Next, FIG. 2 is a functional block diagram showing a configuration example of the arithmetic circuit 7. In addition, here, an a-phase 1-line ground fault will be described as an example.

In FIG. 2, 9 is a setting means, which is a constant Z _α , Z ₀ ,
Z _m , l _A , l _B , l _C , K _B , K _C etc. are set and stored. here,
Z _α , Z ₀ and Z _m are α-mode impedance, zero-phase self-impedance and zero-phase mutual impedance per transmission line unit length respectively, and l _A , l _B and l _C are the terminals A, l _B and l _C as in FIG.
The distances from B and C to the branch point, K _B and K _C are constants related to each branch load.As these constants K _B and K _C , for example, the installed capacity of each branch load or the actual maximum power assumed value, etc. To use.

Further, 10 is a calculation means, which carries out the following calculation by inputting the voltage V, the current I, and the constants Z _α , Z ₀ , Z _m , and outputs Q ₁ , Q ₂ ,
Send Q ₃ , J _V , J _I , and J _L.

Q ₁ = Re {2 ・ I ₀₂ − ▲ V ^* _pol ▼}, Q ₂ = Re {(I ₀₁ + I ₀₂ ) ・ ▲ V ^* _pol ▼} Q ₃ = Re {(I ₀₁ −I ₀₂ ) ・ ▲ V ^* _Pol ▼}, V _0l = V _bc <90 ° J _V = Sm {Va ・ I _D ^* }, J _I = Sm {(Z _α・ I _α ＋ Z ₀・ I ₀₁ ＋ Z _m・ I ₀₂ ) ・ I _D ^* } J _L = Sm {Z _α · (I _α −I ₀₁ ) · I _D ^* } _ID = [fault current] = [value of I _α during fault]-[pre-current value of I _α ] ( *: Conjugate complex number, Re: real part, Sm: imaginary part) Further, 11 is an arithmetic means, which carries out the following arithmetic operation using the above constants K _B and K _C as inputs, and outputs outputs G _B and G _C.

G _B = K _B / K _T , G _C = K _C / K _T , K _T = K _B + K _C (27) On the other hand, 12 is an arithmetic means, which is an output from the setting means 9.
l _A , l _B , l _C , output from the calculation means 10 Q ₁ , Q ₂ , Q ₃ , J _V , J _I , J _L , and output from the calculation means 11 G _B , G _C x _A1 , x
_B1 , x _C1 sending means 13 and outputs x _A2 , x _B2 , x _C2
The arithmetic unit 14 for sending, sends the output x _0, B _r receives the output from the respective operating means 13,14. Here, the calculation means 13 receives Q ₁ , Q ₂ and Q ₃ of the inputs of the calculation means 12 as input,
The outputs x _A1 , x _B1 , x _C1 are output by performing the following calculation. That is, first, the calculation means 16 calculates X _A1 = (Q ₁ / Q ₂ ) · (l _A + l _B l _C ). ) (Where l _B l _C = l _B · l _C / (l _B + l _C ), and so on), and the following comparison means 17 compares the input x _A1 and the input l _A , If x _A1 l _A , this x _A1 is output. Also, x
_{If A1} > l _A , an output N ₁ is produced, which is calculated by the calculating means 18. To output x _B1 To output x _C1 .

In addition, the calculation means 14 is configured so that among the inputs of the calculation means 12, J _V , J _I ,
J _L , G _B , G _C are output and the following calculation is performed and output x _A2 , x _B2 ,
Send x _C2 .

That is, first, the calculating means 20 executes x _A2 = J _V / J _I (31), the next comparing means 21 compares the input x _A2 and the input l _A, and if x _A2 l _A This x _A2 is output. Also, x
If _A2> l _A resulting output N _2, the calculating means _{22 x B2 = l A + (} J V -l A · J I) / (J I -G C · J L) ...... (32) Then, x _B2 is output and x _C2 = l _A + (J _V −l _A · J _I ) / (J _I −G _B · J _L ) ... (33) Output x _C2 .

Further, the judging means 15 outputs the output x _A1 , x _B1 , x from the calculating means 13.
_C1 and the outputs x _A2 , x _B2 , x _C2 from the calculating means 14 are input, the following judgment is performed, and the outputs x ₀ , B _r are transmitted.

(I) When x _A1 and x _A2 are input, output as output x ₀
x _A1 is output as B _r , and the A terminals are output.

(Ii) When x _A1 and x _B2 , x _C2 or x _A2 and x _B1 , x _c1 are input, 1 _A is output as the output x _{0 and the} A terminal is output as the output B _r .

(Iii) When xB1, xC1 and xB2, xC2 are input, | x _B1 −x
_{When B2} || x _C1 −x _C2 |, the output x ₀ is x ₀ = x _B1 , and the output B _r
When | x _C1 −x _C2 | <| x _B1 −x _B2 |, the output x ₀ is x ₀ = x _C1 and the output B _r is the C terminal.

The above description of the calculation means 9 to 11 and 13, 14 is applied to the three-terminal transmission line system of parallel two-rotation lines of FIG. Further, in the equation (26), the term of compensation by the zero-phase active component current of the mating terminal is omitted from the equations of Q ₁ and Q ₂ for simplification of description. In addition, the term due to zero-phase mutual impedance is added to the equation of J ₁ .

Next, the operation of the fault point locating device configured as described above will be described with respect to the fault points F _A , F _B and F _{C in} FIG. In order to simplify the explanation in this case, the failure point F _B is near the terminal B,
It is assumed that the fault point F _C is near the terminal C and l _B is longer than l _C.

First, the failure point will be described for the case of F _A. In this case, since the fault is within the branch point, x _A1 (= x _A ) calculated by Eq. (28) and x _A2 (= x _A ) calculated by Eq. (31) are shown in Fig. 2. Is input to the determination means 15 of, and the orientation result x ₀ = x _A ,
The fault branch line B _r = A terminal (that is, within the branch point) is output.

Next, the case where the failure point is F _B will be described. in this case,
Since the fault is beyond the branch point, x _A1 and x _A2 calculated by equations (28) and (31) are both larger than l _A ,
X calculated by equations (29), (30) and (32), (33)
_B1 , x _C1 and x _B2 , x _C2 are input to the determination means 15. Now consider x _B1 , x _C1 and x _B2 , x _C2 . Since it is assumed that the fault point F _B is near the terminal B, the fault currents I ₀₁ and I ₀₂
Are almost equal, and Q ₃ = 0 in Eq. (26), so x _B1 ,
x _C1 becomes x _B1 = l _A + l _B and x _C1 = l _A + l _C. Also, since x _B2 is the value for the faulty branch line, x _B2 = l _A + l _B
Since x _C2 is a value for a healthy branch line, x _C2 = l _A + l _B when there is no branch load, but generally there is an error due to the difference in branch load when there is a branch load, but x _C2
≒ l _A + l _B

That is, since it is assumed that l _B is longer than l _C, the distance to the terminal C exceeds l _A + l _C , but l _A + l _B is not set because the outputs of the calculation means 22 and 23 are not limited. It is output as x _C2 . Therefore, since x _B1 and x _B2 are equal, the orientation result x ₀ = l _A
+ L _B and the fault branch line B _r = B terminal are output.

Next, a case where the failure point is F _C will be described. In this case, since the fault is beyond the branch point, x _B1 , x _C1 and x _B2 , x
_C2 is input to the determination means 15. Where x _B1 , x _C1 and x
Considering _B2 and x _C2 , from the same explanation as in the case where the above-mentioned failure point is F _B , x _B1 = l _A + l _B , x _C1 = l _A + l _C , x _B2
= L _A + l _C , x _C2 = l _A + l _C. Therefore, since x _C1 and x _C2 are equal, the orientation result x ₀ = l _A + l _C and the fault branch line B _r = C terminal are output.

Next, when the failure point is near the branch point, the outputs x _A1 and x _A2 of the calculation means 16 and 20 and the set value l _A may not match each other due to a calculation error. As a result, the orientation result x ₀ = l _A and the fault branch line B _r = A terminal are output.

As described above, in the fault point locating device according to this embodiment,
Since the fault point is determined using the orientation result by the zero-phase current comparison method and the orientation result by the impedance measurement method, even if a fault occurs beyond the branch line, which branch line has a fault? It is possible to make a distinction.

In the above embodiments, the fault points F _B and F _C are assumed to be near the terminals B and C, but this does not limit the position of the fault point at which the fault branch line can be discriminated to the vicinity of the mating terminal. . In other words, in the zero-phase current comparison method, the position of the fault point is calculated in principle as a ratio to the length of the transmission line, and this is multiplied by the length of the transmission line to output the distance to the fault point. When the line lengths are different, the orientation result for the faulty branch line is equal to the distance to the fault point, but the orientation result for the sound branch line has a large error. On the contrary,
Since the impedance measurement method measures the line voltage drop due to the fault current in principle, the orientation result for the fault branch line is equal to the distance to the fault point even if there is a difference in the length of the branch line, The error of the orientation result about the line is also small. Therefore, when there is a difference in the lengths of the branch lines, it is possible to determine the fault branch line without limiting the position of the fault point to the vicinity of the mating terminal.

Further, in the above embodiment, as the output x ₀ of the judging means 15 in FIG. 2, x _A1 , x _B1 , x _C1 are output, but instead of this,
It is also possible to output x _A2 , x _B2 , x _C2 or the average value of both.

Furthermore, it is also possible to omit the set of either the calculation means 16 and the comparison means 17 or the calculation means 20 and the comparison means 21. For example, if the combination of the arithmetic means 20 and the comparison means 21 is omitted, the arithmetic means 18, 19 and 22, 23 may be configured to be executed when the output N ₁ is sent from the comparison means 17. Good. In this case as well, the determination means 15 can determine the fault branch line.

In addition, the present invention can be variously modified and implemented within the scope of the invention.

[Effects of the Invention] As described above, according to the present invention, in a parallel two-line three-terminal power transmission line system having a branch, a device result of a failure point by the zero-phase current comparison method and a failure point by the impedance measurement method are detected. Since the judgment is made based on the result of comparison with the orientation result, even if a failure occurs beyond the branch point, the distance to the failure point is calculated using only the voltage and current value of its own terminal and the failure branch. A fault point locating device capable of discriminating a line can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of hardware of a fault locating device according to the present invention, FIG. 2 is a functional block diagram showing details of an arithmetic circuit in FIG. 1, and FIGS. 3 to 6 are conventional arts. FIGS. 7 to 14 are diagrams for explaining other conventional techniques, respectively. 1 ... Transmission line, 2 ... Transformer, 3 ... Current transformer, 4,5 ...
Input conversion circuit, 6 ... A / D conversion circuit, 7 ... Arithmetic circuit,
8 ... Output circuit, 9 ... Setting means, 10,11,12,13,14,16,
18,19,20,22,23 …… Computing means, 15 …… Decision means, 17,21
…… Comparison means.

Claims (3)

[Claims] 1. In a parallel two-line three-terminal transmission line system having a branch, an effective component current contained in zero-phase currents of a faulty line and a healthy line is measured by using a measured voltage value of a predetermined one of the three terminals. First fault point locating means for locating a fault point based on the ratio of the magnitudes of the respective extracted zero-phase effective currents, and an assumed distribution ratio of branch load power are set, A branch load current flowing in the branch load is obtained from this set value and the measured current value of the predetermined one terminal, and the difference between the branch load current and the measured current value of the predetermined one terminal and the predetermined one.
A second fault point locating means for locating a line voltage drop due to a fault current using the measured voltage value of the terminal and locating a fault point based on the line voltage drop; and a locating result by the first fault point locating means. By inputting the orientation result by the second fault point locating means and both the orientation results by the first and second fault point locating means are within the branch point, the predetermined one terminal is discriminated as a fault branch line. ,
When the orientation results by the first and second fault point locating means are both beyond the branch point, the difference between the orientation result by the first fault point locating means and the orientation result by the second fault point locating means is smaller. A fault point locating device, comprising: a determining unit that determines a mating terminal as a fault branch line. 2. The fault point locating device according to claim 1, wherein the determining means has one of the orientation results of the first and second fault point locating means within a branch point, and the other is A fault point locating device characterized in that the predetermined one terminal is discriminated as a fault branch line when the distance is beyond the branch point. 3. In a parallel 2-line 3-terminal transmission line system having a branch, an effective component current contained in zero-phase currents of a faulty line and a healthy line is measured by using a measured voltage value of a predetermined one of the 3 terminals. First fault point locating means for locating a fault point based on the ratio of the magnitudes of the respective extracted zero-phase effective currents, and an assumed distribution ratio of branch load power are set, A branch load current flowing in the branch load is obtained from this set value and the measured current value of the predetermined one terminal, and the difference between the branch load current and the measured current value of the predetermined one terminal and the predetermined one.
A second fault point locating means for locating a line voltage drop due to a fault current using the measured voltage value of the terminal, and locating a fault point based on the line voltage drop; and a locating result by the first fault point locating means. By inputting the orientation result by the second fault point locating means and both the orientation results by the first and second fault point locating means are within the branch point, the predetermined one terminal is discriminated as a fault branch line. ,
When the orientation results by the first and second fault point locating means are both beyond the branch point, the difference between the orientation result by the first fault point locating means and the orientation result by the second fault point locating means is smaller. A determination unit that determines the mating terminal as the faulty branch line, and a determination result by the determination unit, and outputs the first or second faulty line in the faulty branch line indicated by the determination result.
And a means for outputting the result of the orientation by the means for locating the fault of (1).