JP2000261959A - System and method for suppressing grounding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize a reverse-phase current to be injected into a system, and to prevent the return of grounding current by suppressing the grounding current by a supplied antiphase current. SOLUTION: When a grounding fault occurs, the phase voltages of bus-bars 3a-3c becomes unbalanced, and a zero-phase sequence voltage V0 is detected in a zero-phase sequence transformer, and zero-phase sequence current I02 I03 are detected by the zero-phase sequence current transformer 7b, 7c of distribution lines 5a-5c, 6a-6c. The zero-phase sequence current transformer 7a of distribution lines 4a-4c detects a resultant current Ig2 of grounding resistance component currents Ira, Irb, Irc from the grounding neural liens of the zero-phase sequence current transformers, and the zero-phase sequence currents I02 I03 detected by the zero-phase sequence current transformers 7b, 7c. From the detected zero-phase sequence voltage V0, zero-phase sequence currents I02 I03 and resultant current Ig2, a grounding fault detector 10 decides that a grounding fault occured. Consequently, a grounding current can always be suppressed stably without returning it, and to obtain in a grounding suppressing system which facilitates extinction of a grounding arc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention suppresses a ground fault itself by suppressing a ground fault current generated due to a ground fault in an instantaneous ground fault or a permanent ground fault occurring in a power distribution line. Further, the present invention relates to a ground fault suppression system and a ground fault suppression method for alleviating a grounding resistance value by a class B grounding work specified in the technical standards for electrical equipment.

[0002]

2. Description of the Related Art Conventionally, when a ground fault has occurred in a power distribution system, a ground fault current flows in a distribution line. As a countermeasure against this ground fault, in a normal case, a ground fault is detected by a zero-phase transformer, a relay that detects a faulty circuit by a zero-phase current transformer operates, and a circuit breaker (distribution line CB) of a distribution line is activated. Open the distribution line to a no-voltage state, and after one minute, the distribution line CB
Is closed, and power is retransmitted to the distribution line.

However, when an instantaneous ground fault occurs due to a temporary contact between a distribution line and a conductive material or the like, a permanent ground fault does not occur, and a ground fault accident is often removed. Performing a reclosing operation in the case of such an instantaneous ground fault involves a power failure,
This will significantly reduce the reliability of the power supply.

Therefore, in the case of an instantaneous ground fault, the distribution line CB
Before the system operates, the ground fault current can be suppressed by a method of instantaneously bypassing the ground fault current from the distribution line by the forced grounding device, or a method of equipping an arc-extinguishing reactor to offset part of the ground fault current. A method of not operating the distribution line CB has been devised.

However, the method of bypassing the ground fault current (providing a bypass circuit in the power source on the power transmission side) does not necessarily reduce the current value of the ground fault current, and does not reduce the type B of the electrical equipment technical standard. The grounding work requires a grounding resistance according to the ground fault current value, which requires a large construction cost.

A method of equipping an arc-extinguishing reactor to cancel a part of a ground fault current (a coil L is connected to a capacitor C)
Is necessary to have a ground point on the power transmission side, and the form of the power transmission side is limited.

Further, even if an arc-extinguishing reactor is used, only the fundamental component of the ground fault current based on the ground capacitance can be canceled, and all the ground fault currents including the resistance component current and the harmonic current are cancelled. This is impossible in principle, and the processing of the remaining ground fault current is an issue.

Further, when the capacitance to ground changes due to a change in the distribution line length, if the reactor capacity is constant,
The current compensation rate will change.

[0009]

Accordingly, a ground fault suppressing system and a ground fault suppressing method which do not depend on the power transmission mode, can suppress additional equipment at low cost, and can suppress the ground fault current are disclosed. An anti-phase current injection method has been devised which suppresses a ground fault current by injecting a current having an opposite phase to the current.

However, in the reverse phase current injection method, when a current detected in the zero-phase variable flow path of the ground fault line is input to the reverse phase waveform generating device as an approximate ground fault current, Input and output to the device will be performed on the same ground fault line.

Therefore, the input to the antiphase waveform generator is
As a result, a residual between the ground fault current and the antiphase current is given.

For this reason, the ground fault current is suppressed and then restored, and then returned and then suppressed. This causes a problem that the ground fault current is hardly extinguished due to the return of the ground fault current. Occurs.

Here, the conventional ground fault current suppressing principle will be described with reference to FIGS. 6 and 7. FIG.

[0014] Figure 6 shows a suppressing equivalent circuit ground fault current I _g. 100 is an equivalent power supply. 101 is a ground fault line. 102 and 103 are healthy lines. C
1, C2 and C3 are the ground capacitances of the ground fault line 101 and the healthy lines 102 and 103, respectively. 104
Is a grounding type voltage transformer (GVT; Grounding Voltage Tr)
a primary ground neutral line of zero-phase transformer comprising a ansformer), resistor R _N is an equivalent resistance converted the primary side of Aru limiting resistor provided in the zero-phase transformer. 105 is a ground fault detection device. 106 is the reverse phase waveform generator for generating a reverse phase current I _V suppresses the ground fault current I _g. 107 is an equivalent zero-phase current transformer corresponding to the zero-phase current transformer installed on the ground fault line 101, and 108 and 109 are zero-phase current transformers installed on the healthy lines 102 and 103. The zero-phase current transformer of the ground fault line 101 cannot detect the current of its own line due to its characteristics.

The current detected by the zero-phase current transformer 108 of the healthy line 102 is a zero-phase current I ₀₂ , and the current detected by the zero-phase current transformer 109 of the healthy line 103 is a zero-phase current I ₀₃ . Further, a resistance component current I _RN flows through the primary-side grounded neutral wire 104 of the zero-phase transformer. On the other hand, the current detected by the original zero-phase current transformer of the ground fault line 101 is a vector sum of I ₀₂ , I ₀₃ , and I _RN .

Here, the ground fault line 101 of the ground fault current
The current generated by the zero-phase current I _g1 (= I ₀₁ ) and the current of the ground fault current generated from the healthy lines 102 and 103 and the primary side neutral neutral line 104 of the zero-phase transformer are represented by I _g2 (= I _02). + I ₀₃
+ I _RN ), and the healthy line 102,1 of the ground fault current.
When the current generated from the 03 only and _{I g3 (= I 02 + I} 03), ground fault current I _g is,

[0017]

I _g = I ₀₁ + I ₀₂ + I ₀₃ + I _RN = I _g1 + I _g2 (1)

Next, the operation of suppressing the ground fault current is as follows.

1. Equivalent zero-phase current transformer 10 of ground fault line 101
In FIG. 7, the ground current I _g , the inflow I _g2 from the healthy line and the primary-side grounded neutral line of the zero-phase transformer, and the antiphase current I _g
Residuals and _{V ΔI g2 (= I g2 +} I V) is detected.

2. The detected residual ΔI _g2 is input to the antiphase waveform generating device 106 through the ground fault detection device 105, and generates and injects an antiphase current _IV corresponding to the residual ΔI _g2 there.

3. Initially injection of opposite phase current I _V, the residual Δ
I _g2 becomes smaller, and the amount of generation and injection of the anti-phase current _IV at the next point in time decreases.

4. When the ground fault continues, the residual ΔI _g2 increases again by an amount corresponding to the decrease in the antiphase current _IV .

The processing of 5.1 to 4 is repeated, and the suppression rate is settled at a certain level.

In this manner, the combined current I _g2 (= I ₀₂ + I ₀₃ + I _RN) of the zero-phase current of the healthy line and the inflow from the grounded neutral line on the primary side of the zero-phase transformer of the ground fault current. ) Decreases. Therefore, the ground fault current I _g (= I _g1 +
_Ig2 ) also decreases.

FIG. 7 is a vector diagram showing the principle of suppressing the ground fault current I _g in prior art, FIG. 7 (a) in the case of not applying the antiphase waveform generator normal ground fault condition, Figure 7
7B shows a state at a certain point in time when the anti-phase waveform generator is applied in the state of FIG. 7A, and FIG.
FIG. 8B shows a state at a time different from that in FIG. 7B when the antiphase waveform generator is applied in the state of FIG. The residual ΔI _g2 (= I _g2 + I _v ) is the zero-phase current transformer 1 in FIG.
07 is always monitored. At the beginning of the ground fault, the residual ΔI _g2
Is equal to I _g2 , and the corresponding antiphase current I _v (= −Δ
I _g2 ) is generated and injected (see FIGS. 7A and 7B).
After injection, as shown in FIG. 7 (b), the residual [Delta] I _g2 decreases, correspondingly grounding current I _g is also suppressed. However, since the residual ΔI _g2 is constantly monitored, at the next instant, the opposite phase current _IV becomes a small current as shown in FIG. 7C. In addition, since each of the currents I ₀₂ , I ₀₃ , and I _RN tends to flow as before, I _g2 (= I ₀₂ + I ₀₃ + I _RN ) attempts to return to the original size. Therefore, the effect of suppressing I _g2 is reduced, and the effect of suppressing the ground fault current I _g (= I _g1 + I _g2 ) is also reduced.

[0026] Such FIG. 7 (b), the by repeating the operations of (c), as described above, and the ground fault current I _g is restored, ground fault arc remains a problem that extinguishing to hesitation .

Accordingly, an object of the present invention is to provide a ground fault suppressing system and a ground fault suppressing method which stabilize the reverse phase current injected into the system, prevent the return of the ground fault current, and easily extinguish the ground fault arc. It is in.

[0028]

According to the present invention, a ground fault current in a power distribution line having a plurality of distribution lines connected to a common bus is suppressed. A zero-phase voltage detecting means for detecting a zero-phase voltage of the power distribution line, and a zero-phase current detecting means for detecting each zero-phase current of the power distribution line. Sound phase discriminating means for discriminating a healthy line based on the current, approximate ground fault current calculating means for calculating an approximate ground fault current based on the vector sum of the zero phase current of the determined healthy line, and the calculated An anti-phase current generating means for generating an anti-phase current having an anti-phase with the approximate ground fault current, and an anti-phase current supplying means for supplying the generated anti-phase current to the power distribution line. Previous by antiphase current By so as to suppress the ground fault current, constitutes the land 絡抑 control systems.

According to the present invention, a ground fault current in a power distribution line having a plurality of distribution lines connected to a common bus is suppressed, and a zero-phase voltage of the power distribution line is detected. And a zero-phase current detection means for detecting each zero-phase current of the distribution line, and a ground fault based on the zero-phase voltage and the current detected in the zero-phase current detection step. Ground fault detection step of detecting the zero phase current detection step, a healthy phase determination step of determining a healthy line based on the current detected in the zero phase current detection step, based on the vector sum of the determined zero phase current of the healthy line An approximate ground-fault current calculating step of calculating an approximate ground-fault current, an anti-phase current generating step of generating an anti-phase current having a phase opposite to the calculated approximate ground-fault current, and the generated anti-phase current. To the power distribution line Comprising a phase opposite current supply step of supplying, by so as to suppress the ground fault current by the supplied antiphase current, constitutes the land 絡抑 system method.

In this configuration, the calculation of the vector sum of the zero-phase current of the healthy line is performed on the zero-phase current of the healthy line after the transient state immediately after the occurrence of the ground fault. Good.

[0031]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(System Configuration) FIG. 1 shows a configuration example of a ground fault suppression system according to the present invention.

In the premises of the distribution substation 1, reference numeral 2 denotes a power supply (power supply transformer). The output side of the power supply 2 is connected to distribution lines 4a to 4c, 5a to 5c, via buses 3a to 3c.
6a to 6c.

The buses 3a to 3c are connected to a zero-phase transformer 8 including a ground-type instrument transformer (GVT) for detecting a zero-phase voltage Vo. Distribution lines 4a-4c, 5a-5c,
Zero-phase current transformers 7a to 7c are connected to 6a to 6c.

Reference numeral 10 denotes distribution lines 4a to 4c, 5a to 5c,
Or a ground fault detecting device as ground fault current detecting means for detecting an accident through the distribution line approximation grounding current _{I g3 (= I 02 + I} 03) of the 6 a to 6 c. FIG. 1 shows a case where the distribution lines 4a to 4c are accident distribution lines.
The input side of the ground fault detector 10 is connected to a zero-phase current transformer 7a.
7c, a zero-phase transformer 8 and instrument transformers 9a to 9c are connected. The output side of the ground fault detector 10 is provided with an antiphase waveform generator 20 and a switch 4
1 are connected.

[0036] 20 is a reverse phase waveform generator as opposite phase current generating means for generating an approximate ground fault current I _g3 opposite phase of opposite phase current I _v (= -I _g3). The input side of the antiphase waveform generator 20 is connected to the output side of the ground fault detector 10. The output side of the anti-phase waveform generator 20 is connected to the injection transformer 40.

Loads 30, 31, and 32 are respectively connected to the distribution lines 4a to 4c, 5a to 5c, and 6a to 6c drawn from the distribution substation 1. C ₀₁ is distribution line 4
4a to 4c and the ground capacitance between each phase and the ground. C
₀₂ is a ground capacitance between each phase of the distribution lines 5a to 5c and the ground. C ₀₃ is a ground capacitance between each phase of the distribution lines 6a to 6c and the ground.

FIG. 2 shows the internal configuration of the ground fault detection device 10. The device 10 includes an input unit 11 to which various signals are input, and an accident detection unit 12 for detecting a ground fault.
And a comparison unit 13 for detecting a phase in which a ground fault has occurred and a sound distribution line in which a ground fault has not occurred, and a command to turn on a switch 41 for system insertion into the ground fault phase. A switch-on commanding unit 14 to be _operated, and an arithmetic unit 15 for calculating an approximate ground-fault current _Ig3 to be input to the antiphase waveform generator 20;
A command to turn on the switch 41 for system paralleling and the approximate ground fault current I
_g3 and an output unit 16 for outputting _g3 .

FIG. 3 shows the internal configuration of the anti-phase waveform generator 20. The device 20 includes an input section 21 to which an opposite phase current generation command is input, a waveform generating section 22 for generating the same phase waveform as the input signal waveform, a waveform inverting section 23 for inverting the generated waveform, Output unit 24 that outputs I _v
It is composed of

(Ground-Fault Current Suppression Operation) Next, the operation of the ground-fault suppression system will be described.

Assume that a ground fault has occurred in the c-phase distribution line 4c among the distribution lines 4a to 4c. In this case, among the distribution lines 4a to 4c, the bus 3a has an a-phase distribution line 4a.
, The zero-phase current i ₀₁ based on the ground capacitance C ₀₁ , the zero-phase current i ₀₂ based on the ground capacitance C ₀₂ from the a-phase distribution line 5a among the distribution lines 5a to 5c, and the distribution lines 6a to 6c 6c, the zero-phase current i ₀₃ based on the ground capacitance C ₀₃ from the a-phase distribution line 6a and the ground-fault resistance component current from the grounding neutral line 8a of the zero-phase transformer 8 to the a-phase The combined current with the flowing amount _Ira flows as indicated by the dashed arrow.

The bus 3b includes, among the distribution lines 4a to 4c,
from b-phase distribution line 4b and a zero-phase current i ₀₁ based on the earth capacitance C _01, of the distribution line bodies 5a to 5c, b-phase distribution line 5b
, A zero-phase current i ₀₂ based on the ground capacitance C ₀₂ , a zero-phase current i ₀₃ based on the ground capacitance C ₀₃ from the b-phase distribution line 6b among the distribution lines 6a to 6c, and a zero-phase transformer. 8 of the ground-fault resistance current from the ground neutral wire 8a
The combined current with _rb flows as indicated by the dashed arrow.

The bus 3c includes the distribution lines 5a to 5c
a zero-phase current i ₀₂ based on the earth capacitance C ₀₂ from c-phase distribution line 5c, of the distribution line 6 a to 6 c, c-phase distribution line 6c
Out of the zero-phase current i ₀₃ based on the ground capacitance C ₀₃ and the ground-fault resistance current from the ground neutral line 8 a of the zero-phase transformer 8.
A combined current with the current I _rc flowing in the c-phase flows as indicated by the dashed arrow.

The combined current of the zero-phase current and the resistance component current flowing through the buses 3a to 3c finally becomes the fault distribution lines 4a to 4c.
Flow into the ground fault point G of the accident phase 4c as shown by the dashed arrow. That is, the combined currents of the zero-phase current and the resistance component current flowing in the buses 3a and 3b flow to the bus 3c via the power supply 2 as shown by the dashed arrows, become the combined current again, and
It flows to the accident phase 4c of a to 4c, and flows to the ground fault point G.

On the other hand, in the event of a ground fault, the phase voltages of the buses 3a to 3c become unbalanced, the zero-phase voltage Vo is detected by the zero-phase transformer 8, and the distribution lines 5a to 5c, 6a to 6
c, each zero-phase current I ₀₂ ,
I ₀₃ is detected. Zero-phase current transformer 7a of distribution lines 4a to 4c
Then, the zero-phase currents I ₀₂ , I ₀₃ detected by the zero-phase current transformers 7b, 7c and the ground-fault resistance component currents I _ra , I _rb , I _rc from the grounding neutral line 8a of the zero-phase transformer 8 are combined current I _g2 of is detected. These detected zero-phase voltage Vo, zero-phase current I ₀₂ ,
It is possible to determine that a ground fault has occurred in the ground fault detection device 10 from I ₀₃ and I _g2 .

In the ground fault accident detecting apparatus 10, the bus 3
By comparing the phase voltages Va to Vc of the respective phases detected by the instrument transformers 9a to 9c connected to the a to 3c,
The ground fault phase can be easily determined.

The zero-phase currents i ₀₂ , i ₀₃ flowing through each phase of each healthy line, the zero-phase currents I ₀₂ , I _{03 of} each healthy line, and the currents detected by the zero-phase current transformer of the ground fault line The relationship with _Ig2 is as follows.

[0048]

I _g2 = I ₀₂ + I ₀₃ + I _ra + I _rb + I _rc (2)

[0049]

## EQU3 ## I ₀₂ = 3i ₀₂ (3)

[0050]

## EQU4 ## I ₀₃ = 3i ₀₃ (4) Here, the internal processing of the ground fault detecting apparatus 10 shown in FIG. 2 will be described in detail.

The input section 11 receives the zero-phase voltage Vo, the currents I ₀₂ , I ₀₃ , and Ig ₂ detected by the respective zero-phase current transformers, and the phase voltages Va to Vc of the respective phases. In the accident detection unit 12,
Zero-phase voltage Vo and currents I ₀₂ and I detected by each zero-phase current transformer
Looking at both magnitudes of ₀₃ and _Ig2 , when both change (AND condition), it is determined that a ground fault has occurred. At this time, the current detected by the zero-phase current transformer is at least 1
Just look at the two sizes.

When the ground fault is detected in this way, the comparing unit 13 compares the magnitudes of the phase voltages Va to Vc of each phase, and determines the phase having the smallest value as the ground fault phase. .

The comparing section 13 distinguishes a ground fault line from a healthy line based on the zero-phase voltage and the magnitudes and phase differences of the currents I ₀₂ , I ₀₃ , and I _g2 detected by the zero-phase current transformer. By doing so, the approximate ground fault current I _g2 is distinguished from the zero-phase currents I ₀₂ and I ₀₃ flowing through the healthy line. In addition, the same principle as that of the direction relay generally used in the distribution system is used for this determination method. Further, the peak values of the currents detected by the respective zero-phase current transformers are compared with each other, and a line having the maximum peak value is determined as a ground fault line.

The switch closing command section 14 receives the ground fault phase discrimination signal output from the comparing section 13 and receives the signal from the injection transformer 40.
Is output to the switch 41 linked to the ground fault phase.

On the other hand, the arithmetic unit 15 obtains the vector sum based on the zero-phase currents I ₀₂ and I ₀₃ of the healthy circuits 5 a to 5 c and 6 a to 6 c determined by the comparing unit 13 to obtain an approximate ground fault current I _g3. Is calculated. This vector sum is obtained by adding instantaneous values.

The calculation of the vector sum is preferably performed on the zero-phase currents I ₀₂ and I ₀₃ of the healthy lines 5a to 5c and 6a to 6c after the detection of the ground fault. It may be performed for the zero-phase currents I ₀₂ and I ₀₃ of the healthy circuits 5a to 5c and 6a to 6c after the above.

When the vector sum is calculated with respect to the zero-phase current of the healthy line after passing this transient state,
A timer function is provided in the ground fault detector 10, and a predetermined time, for example, 100 ms after the ground fault is detected.
This can be performed for the sum of the zero-phase currents of the healthy line after a certain degree has passed.

Further, the zero-phase current of the healthy line detected in the transient state after the detection of the ground fault has an irregular waveform and a high frequency component. Since the zero-phase current of a healthy line detected later has a stable waveform and does not have a high-frequency component as high as in a transient state, its signal processing is facilitated. Therefore, as described above, by calculating the vector sum for the zero-phase current of the healthy line after the transient state has passed, the transient period is masked to detect the ground fault accident. Although a little time of about 100 ms is a waste of time, the signal processing means for the zero-phase current in a healthy line can be made simple, so that the cost of the ground fault suppression system can be reduced.

The approximate ground fault current I _g3 calculated in this manner
Is output to the antiphase waveform generator 20 via the output unit 16, while the closing command signal It is output to the switch 41 for system parallelization via the output unit 16.

In the anti-phase waveform generator 20, the approximate ground fault current _{Ig 3} is input to the input section 21. The waveform generator 22 generates the same current waveform as the input approximate ground fault current signal as needed. In the waveform inverting unit 23, the waveform generating unit 22
Is inverted so that the current waveform generated in step (1) has an opposite phase to the ground fault current. The anti-phase current I _v thus generated is output from the output unit 24 to the injection transformer 40.

The anti-phase current I _v output to the injection transformer 40 flows through the bus 3c as shown by the solid line arrow, flows into the ground fault phase 4c of the ground fault lines 4a to 4c, and flows into the ground fault point G. , suppressing the ground fault current I _g.

In the above-described ground fault suppression system shown in FIG. 1, a malfunction protection resistor circuit 42 having a resistance of several Ω is provided in parallel with the injection transformer 40. In the system shown in FIG. 1, even if the injection transformer 40 is connected to the sound phase due to erroneous determination of the ground fault phase, the above-described resistance circuit 4
2 is the transformation ratio of the injection transformer 40 on the distribution system side.
By acting in proportion to the power, a short-circuit current due to a different-phase ground fault short-circuit can be reduced.

(Principle of Ground Fault Current Suppression) Next, the principle of ground fault current suppression will be specifically described with reference to FIGS.

[0064] Figure 4 shows a suppressing equivalent circuit ground fault current I _g. Note that, here, the same reference numerals are used for the same portions, for the sake of comparison with the above-described equivalent circuit of FIG.

[0065] land suppressing operation of the fault current I _g is as follows.

[0066] (1) location of the fault current I _g, of the zero-phase transformers each consisting of healthy zero-phase flows through the line 102 and 103 current I _02, the sum and the ground-type instrument transformers of I ₀₃ (GVT) The residual (= I _g2 + I _v = I ₀₂ + I ₀₃ ) between the combined current I _g2 (= I ₀₂ + I ₀₃ + I _RN ) with the resistance component current I _RN flowing from the primary side grounded neutral wire 104 and the opposite phase current I _v + I _RN + I _v ) is not monitored, and the sum I _g3 (= I ₀₂ + I ₀₃ ) of the zero-phase current of each healthy line is not monitored.
Monitor only.

(2) The sum I _g3 (=
I ₀₂ + I ₀₃ ) to generate an antiphase current I _v and inject it into the distribution system.

(3) Ground fault current I _g (= I ₀₁ + I ₀₂ + I ₀₃
+ I _RN ), the sum of the zero-phase currents I _g3 (= I
₀₂ + min by inhibiting the I _03), inhibiting the ground fault current I _g.

[0069] (4) zero-phase current of each sound line, in order to continue to flow as long as the ground fault cause of the accident is not removed, the ground fault current I _g
Even if the residual between the anti-phase current I _v and the anti-phase current I _v becomes small, the amount of generation and injection of the anti-phase current I _v does not decrease, and the ground fault current is stably suppressed.

[0070] Figure 5 is a vector diagram showing the principle of suppressing the ground fault current I _g according to the invention, FIG. 5 (a) in the case of not applying the antiphase waveform generator normal ground fault condition, Figure 5
FIG. 5B shows a state in which the anti-phase waveform generator is applied in the state of FIG. Zero-phase currents I ₀₂ and I _{03 of} each healthy line shown in FIG. 5A are detected by the zero-phase current transformers 108 and 109 of the equivalent circuit of FIG. 4, respectively, and the sum I _g3 (= I ₀₂ + I _{03) is obtained.} ) Is always monitored. The antiphase current I _V (= -I _g3) As shown in FIG. 5 (b) in accordance with I _g3 is generated by being injected, among the ground fault current I _g, min I _g3 is suppressed, ground fault current I _g is also suppressed.

[0071] Incidentally, as follows idea to arrange again the relationship between the resistance component current flowing in the primary side ground neutral line of the ground fault current I _g and the zero-phase current and zero-phase voltage unit for each line.

[0072]

I _g = I ₀₁ + I ₀₂ + I ₀₃ + I _RN = I _g1 + I _g3 + I _RN = I _g1 + I _g2 (5) where I _g1 = I _{01 Ig 2} = I _g3 + I _RN I _g3 = I ₀₂ + I ₀₃ I ₀₁ : Zero-phase current flowing through the ground fault line 101 itself, which cannot be detected by the zero-phase current transformer.

I ₀₂ : Zero-phase current flowing in the healthy line 102

I ₀₃ : Zero-phase current flowing in the healthy line 103

I _RN : Neutral wire 10 on the primary side of the zero-phase transformer
As resistance component current or flowing at 4, in the land絡抑control systems and land絡抑system process according to the invention, of the ground fault current I _g where as in the prior art flows in the earth絡回line, zero-phase flowing to the healthy line The current I _g2 (= I ₀₂ + I ₀₃ + I) obtained by combining the current and the resistance component current I _RN flowing from the primary-side neutral wire of the zero-phase transformer.
_RN) and residuals opposite phase current _{I V (= I g2 + I} V = I 02 +
_{I 03 + I RN + I V} ) instead of monitoring, because you have to monitor only the sum _{I g3 (= I 02 + I} 03) of the zero-phase current of each sound channel to return the ground fault current I _g It is possible to stably suppress the occurrence without any problem.

In the configuration example of FIG. 1, as described above,
A switch 41 is provided between the power distribution line and the injection transformer 40, and the injection transformer 20 is turned into a ground fault phase by a closing operation of the switch 41 by the switch closing signal It from the ground fault detection device 10. Although the configuration is interconnected, the configuration of the ground fault suppression system according to the present invention is not limited to the above,
The configuration may be such that the injection transformer 40 is connected to an arbitrary phase of the power distribution line. With such a configuration, the step of selecting a phase for interconnecting the injection transformer 40 can be omitted, so that the configuration of the ground fault detection device 10 can be simplified.

[0077]

As described above, according to the present invention,
An approximate ground fault current is calculated based on the vector sum of the zero-phase current of the healthy line, and a reverse-phase current having a phase opposite to the calculated approximate ground fault current is supplied to the power distribution line. The present invention can provide a ground fault suppression system and a ground fault suppression method that can stably suppress current without returning the current and easily extinguish a ground fault arc.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a ground fault suppression system according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a circuit configuration of the ground fault detection device.

FIG. 3 is a block diagram showing a circuit configuration of the anti-phase waveform generator.

FIG. 4 is a circuit diagram showing the principle of ground fault current suppression according to the present invention.

5A and 5B are vector diagrams showing the principle of ground fault current suppression according to the present invention, wherein FIG. 5A is a normal ground fault state when an anti-phase waveform generator is not applied, and FIG. The state when the anti-phase waveform generator is applied in the state is shown.

FIG. 6 is a circuit diagram showing a conventional ground fault current suppressing principle.

7A and 7B are vector diagrams showing a conventional ground fault current suppression principle, where FIG. 7A shows a normal ground fault state when an antiphase waveform generator is not applied, and FIG. 7B shows a state of FIG. 7A. 7C shows a state at a certain time when the anti-phase waveform generator is applied, and FIG. 7C shows a state at a time different from FIG. 7B when the anti-phase waveform generator is applied in the state of FIG. Indicates the status.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Distribution substation 2 Power supply (power supply transformer) 3a-3c Bus 4a-4c Distribution line (accident distribution line) 5a-5c Distribution line (healthy distribution line) 6a-6c Distribution line (healthy distribution line) 7a-7c Zero Phase current transformer 8 Zero-phase transformer 8a Zero-phase transformer primary-side grounded neutral wire 9a to 9c Instrument transformer 10 Ground fault detection device 20 Reverse phase waveform generator 30-32 Distribution line load 40 Injection transformer vessel 41 lines parallel needful switches 42 malfunction during protection resistor circuit I _g grounding current I _V antiphase current V ₀ the zero-phase voltage I _g2, I _02, I ₀₃ distribution line 4 a to 4 c, bodies 5a to 5c, 6
currents detected by the zero-phase current transformers a to 6c

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Takashi Motoharu 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Inside Kansai Electric Power Company (72) Inventor Hiroshi Endo 1st Tanabe Nitta, Kawasaki-ku, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture No. 1 Fuji Electric Co., Ltd. (72) Yu Isozaki, Inventor 1-1 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Fuji Electric Co., Ltd. (72) Hiromi Iwai 1st Tanabe Nitta, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture No. 1 Inside Fuji Electric Co., Ltd. (72) Inventor Toshiro Matsumoto 1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture F-term inside Fuji Electric Co., Ltd. 2G014 AA04 AA08 AA27 AB25 AB33

Claims (4)

[Claims] 1. A zero-phase voltage detecting means for suppressing a ground fault current in a power distribution line having a plurality of distribution lines connected to a common bus, and detecting a zero-phase voltage of the power distribution line. And a zero-phase current detecting means for detecting each zero-phase current of the distribution line, and a ground fault which detects a ground fault based on the zero-phase voltage and the current detected by the zero-phase current detecting means. Detecting means, sound phase determining means for determining a healthy circuit based on the current detected by the zero-phase current detecting means, and an approximate ground fault current based on a vector sum of the determined zero-phase current of the healthy circuit. An approximate ground fault current calculating means for calculating; an antiphase current generating means for generating an antiphase current having a phase opposite to the calculated approximate ground fault current; and supplying the generated antiphase current to the power distribution line. Out of phase current And a supply means for suppressing the ground fault current by the supplied antiphase current. 2. The method according to claim 1, wherein the calculation of the vector sum of the zero-phase current of the healthy line is performed on the zero-phase current of the healthy line after a transient state immediately after the occurrence of the ground fault. 2. The ground fault suppression system according to 1. 3. A zero-phase voltage detecting step for suppressing a ground fault current in a power distribution line including a plurality of distribution lines connected to a common bus, and detecting a zero-phase voltage of the power distribution line. And a zero-phase current detection step of detecting each zero-phase current of the distribution line, and a ground fault that detects a ground fault based on the zero-phase voltage and the current detected in the zero-phase current detection step. A detecting step, a healthy phase determining step of determining a healthy line based on the current detected in the zero-phase current detecting step, and an approximate ground fault current based on a vector sum of the determined zero-phase current of the healthy line. An approximate ground fault current calculating step of calculating; an antiphase current generating step of generating an antiphase current having a phase opposite to the calculated approximate ground fault current; and supplying the generated antiphase current to the power distribution line. Out of phase current A supply step, wherein the ground fault current is suppressed by the supplied opposite phase current. 4. The method according to claim 1, wherein the calculation of the vector sum of the zero-phase current of the healthy line is performed on the zero-phase current of the healthy line after a transient state immediately after the occurrence of the ground fault occurs. 3. The ground fault suppression method according to 3.