JPH0783565B2 - Ground fault point recognition device for distribution lines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an apparatus for recognizing a ground fault occurrence and a ground fault point of a distribution line.

B. Outline of the Invention The present invention comprises a ground fault point recognition device composed of a plurality of slave stations installed at respective switch points of a distribution line, and a master station for controlling each slave station. The zero-phase current of the wire is measured and the maximum value is treated as the ground fault current detection value, and this ground fault current detection value is sent to the master station, and the master station also detects the ground fault current value from each slave station. Received
Based on the distribution of the ground fault current detection value, the presence or absence of a ground fault is determined for each switch as a unit, and a slight ground fault condition before the occurrence of a ground fault accident, or intermittent or non-continuous It is possible to recognize the occurrence of a non-entrance accident and the section in which it occurs.

C. Conventional technology The distribution system is an enormous and important facility that spreads across the area, but there are many risks of accidents due to wind and flood damage, lightning, and other factors. For this reason, protective measures are taken in the event of an accident in the distribution line.

Figure 16 shows an example of a ground fault in a distribution line.

When a ground fault occurs on the distribution line 1 (1A, 1B ... 1n), the ground type instrument transformer (G) connected to the bank bus 201 of the substation 2
The ground fault voltage V ₀ is detected by PT) 202, and the ground fault overvoltage relay (OVG) 203 operates at this ground fault voltage V ₀ . Further, to detect the ground fault current I ₀ at the zero-phase current transformer ZCT204 installed in each feeder, earth fault directional relay (DG) 205 on both the ground voltage V ₀ and the ground fault current I ₀ element Works.

Understand the ground fault accident by the operation of OVG203 and DG205,
Feeder circuit breaker (FCB) 206 (206A, 2)
06B ... 206n) is shut off.

In a special ground fault condition or high resistance ground fault, DG20
There is a so-called micro-ground fault state in which 5 does not operate and only OVG203 operates. In this case, the FCB 206 cannot be automatically shut off, and the ground fault occurrence feeder cannot be immediately recognized.

In this case, the FCB2
06A, 206B ... OV by manual or automatic sequence control
It shuts off in order until G203 stops its operation, and prohibits the feeding of the detected FCB206 of the feeder.

After this, the section where the ground fault has occurred is specified.

As shown in FIG. 16, when the ground fault generating feeder is the distribution line 1A, the OVG203 stops operating when the FCB206A is cut off, and therefore the FCB206A is prohibited from being turned on.

A large accident of ground fault current I ₀ occurred and OVG203 and DG205
When both of them operate and the FCB 206a is shut off, the section switches DM _{1 to} DM ₃ are automatically switched to a non-voltage open state.

After a certain period of time, the FCB206A is turned on again by the reclosing control function in the substation 2. As a result, first, a voltage is applied to the section switch DM ₁ .

Here, a closing delay time period X is set for each of the section switches DM _{1 to} DM ₃ . The section switch DM ₁ is turned on after the X time period has elapsed since the voltage was applied. The section switch DM _{2 is} also turned on after the X time limit. If a landslide occurs in section 2 and the situation continues, OVG203 is restarted when the section switch DM ₂ is turned on.
And DG205 works.

The substation 2 monitors the time from when the FCB206A is turned on to when the FCB206A is turned off again. From this time, the section where the ground fault has occurred is recognized. In this case, since the time until re-interruption is 2X, the section 2 can be specified.

After that, in the detected section, maintenance personnel searched for a ground fault and investigated the cause of the accident.

D. Problem to be Solved by the Invention However, in the above-mentioned conventional technique, in identifying the ground fault occurrence section, it is necessary to re-block the FCB206 of the ground fault occurrence feeder, so that a healthy section in the feeder On the other hand, there was a problem that power outages were forced to occur multiple times.

Further, when the section switch immediately before the ground fault point is turned on, the ground fault occurrence section cannot be specified unless the ground fault state continues.

The most common failure mode of the distribution system is temporary leakage of the insulator of the distribution line and intermittent ground fault due to temporary contact of trees with the distribution line.

In this type of ground fault, the ground fault is often resolved at the time when the reclosing control is performed, so that it becomes impossible to recognize the section where the ground fault has occurred, and the normal operation is resumed. However, similar accidents may occur repeatedly because the accident factors have not been fundamentally removed.

Furthermore, even if the section where the ground fault occurs can be detected, it is not known which part of the section is divided by the partial switch in the section, so the search must cover the entire section. There was a problem that spends a lot of time.

Furthermore, in the case of a micro-ground fault accident in which the DG205 does not operate, it is necessary to sequentially shut off the FCBs of the feeders in one bank to identify the feeder that causes the micro-ground fault. In that case, all the FCBs in one bank would be shut off, and there was a problem that a wide-range power outage would be forced as in the case of a bank all-outage accident. Further, similarly to the case of specifying the ground fault occurrence section, there is a problem that the ground fault occurrence feeder cannot be specified unless the ground fault condition continues.

Furthermore, it is not recognized as a ground fault because it is the procedure to detect the ground fault occurrence section etc. after the ground fault occurs.
It was impossible to detect the ground fault occurrence section and so on for a slight ground fault condition in which neither OVG203 nor DG205 operated. Even in the case of a slight ground fault, preventive maintenance measures could not be implemented despite the possibility of gradually developing into a ground fault accident, such as salt adhesion to the insulator.

It is desirable to solve these problems in terms of service to power consumers and reliability of power supply.

In view of such circumstances, the present invention provides a fine ground fault accident in which only OVG operates, and even in a slight ground fault condition before a ground fault accident in which OVG does not operate, the FCB shutoff operation is performed. An object of the present invention is to provide a device capable of recognizing a ground fault state and a ground fault point without being accompanied, and further capable of recognizing an intermittent ground fault point, which has been conventionally impossible to detect.

E. Means for Solving the Problems The present invention, in order to achieve the above object, comprises a plurality of slave stations installed at each switch point of a distribution line and a master station that controls each slave station. The entanglement recognition device is configured, and the following means are provided in each slave station and master station.

That is, the following means are provided in the slave station.

 Zero-phase current detector that measures the zero-phase current of the distribution line.

A ground fault current storage unit that stores the maximum value of the detection signal of the zero-phase current detection unit as a ground fault current detection value.

A ground fault current detection value transmission unit that transmits the ground fault current detection value to the master station.

In addition, the following means will be provided in the master station.

A ground fault current detection value receiving unit that receives the ground fault current detection value from each slave station.

Based on the ground fault current detection value from each slave station, the ground fault recognition unit that sequentially determines the presence or absence of the ground fault from the power supply side by comparing and determining the magnitude of the ground fault current detection value in units of switches. .
As a method of recognizing the magnitude of the "difference in ground fault current detection value",
In addition to a mode in which the difference between the local-fault current detection values is determined and the magnitude thereof is determined, a mode in which the ratio of the local-fault current detection values is determined and the magnitude is determined can be employed.

Further, the ground fault recognition section includes the following means.

A non-branch section determination unit that determines a non-branch section other than the power supply section and the terminal section and determines that there is a ground fault point in the non-branch section when the difference between the front and rear ground fault current detection values is large.

When the branch section is the target of discrimination, the ground fault current detection values on the branch load side are compared with each other, and if all the differences are small, the area on the power supply side, that is, the ground section or the section on the power supply side from the branch section A ground fault area determination unit that determines that there is a fault point and, if any of these differences is large, determines that there is a ground fault point in the load side region, that is, in any of the branched load sides.

When there is a ground fault point in the area on the power supply side, the difference between the ground fault current detection value on each branch load side and the ground fault current detection value on the power supply side in that branch section is taken.
A branch section discriminating unit that judges that there is a ground fault point in the branch section and judges that there is a ground fault point on the power supply side of the branch section when the difference is small.

When there is a ground fault point in the area on the load side, the load side identification unit that compares the ground fault current detection values on the load side and determines that the ground side fault point is on the load side with the maximum ground fault current detection value.

The end section is used as a determination target, the magnitude of the ground fault current detection value on the power supply side of the end section is determined, and when the ground fault current detection value is larger than a certain value, there is a ground fault point in the end section. When it is small, the terminal section discriminating unit that judges that there is a ground fault point in the power source section.

F. Action According to the present invention, the zero-phase current of the distribution line is measured at the slave station installed at each switch point, and the maximum value of the zero-phase current of each slave station is sent to the master station as the ground fault current detection value. Send.

When a ground fault occurs in the distribution line, a large ground fault current flows from the power supply side to the ground fault occurrence point toward the ground fault occurrence point from the power supply side via the ground capacitance of another feeder, causing a ground fault. At the switch point at the latter stage of the generation point, a small amount of ground fault current flows toward the ground fault generation point through the ground capacitance only at the rear stage of the own feeder. Therefore, the difference in the ground fault current is the largest before and after the ground fault occurrence point.

In consideration of this phenomenon, the master station sequentially determines whether or not a ground fault has occurred in units of switches based on the ground fault current detection value from each slave station.

That is, for non-branch sections other than the power section and the terminal section, check whether there is a large difference in the ground fault current detection values before and after, and if there is such a section, a ground fault has occurred in that section. To judge.

Regarding the branch section (including the branch section if the power section is a branch section), first check the distribution status of the ground fault currents by comparing the ground load current detection values on the branch load side with each other, It is determined whether the ground fault point exists in the side area or the load side area.

When there is a ground fault point in the area on the power supply side, the ground fault current detection value on the power supply side of the branch section is compared with the ground fault current detection value on each branch load side, and there is a ground fault point on the branch section. Determine if If there is no ground fault in the branch section, it is known that the power section has a ground fault.

If the load side region has a ground fault point, it is determined that the load side having the maximum ground fault current detection value has the ground fault point, and the section on the load side is determined.

As a result of the determination in this way, when the determination target is the terminal section, it is determined whether or not there is a ground fault point in the terminal section based on the magnitude of the ground fault current detection value on the power supply side of the terminal section. If there is no ground fault in the terminal section, it can be seen that there is a ground fault in the power section.

G. Examples Examples of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of an embodiment of the present invention.

In the substation 2, when a ground fault occurs, the FCB 206 shuts off the power supply to the distribution line 1 in which the fault occurred. In addition, the accident information transmitting unit 207 transmits information about the ground fault to the master station 6 (described later) of the ground fault recognition device.

The distribution lines 1, 1 ... Transmit electric power supplied from the substation 2. A plurality of switches 3, 3, ... Are installed on the distribution line 1 at predetermined intervals.

Each switch 3 includes a contact 301 provided on the distribution line 1 and an operation coil 302 for operating the contact 301. Further, the zero-phase current transformer (ZCT) 303 detects the zero-phase current flowing through the distribution line 1, and the opening / closing operation detection unit 304 detects the opening / closing operation of the contact 301. Switch controllers 4,4 ... are each switch 3,3
It is attached to ... and controls the operation of each switch 3, 3.

The ground fault point recognizing device according to the present embodiment is composed of slave stations 5, 5 ... Attached to the switches 3, 3, ... And a master station 6 for controlling each slave station 5, 5. Each slave station 5, 5 ... and the master station 6 have an information transmission line 7
Connected by.

A mode in which only the section switches are targeted as switches for installing the slave stations 5, 5 ... (Refer to FIG. 2), or a mode in which the section switches and partial switches within the section are targeted (Refer to FIG. 3) ) Etc. can be selected.

In the slave station 5, the ZCT output is received by the auxiliary CT 501, and the received signal is amplified by the amplifier 502 to a level required for the signal processing of the next stage. Then, after periodically sampling and A / D converting by the A / D converter 503, in order to remove the influence of the nozzles, etc., after smoothing by the smoothing calculation unit 504,
The maximum value storage unit 505 takes the maximum value of the current detection value and stores it as the ground fault current detection value I ₀ . This maximum storage unit 505
The stored contents are not erased even if the FCB 206 is opened and there is no power supply, and the stored contents are initialized by the reset signal. The information transmission unit 506 performs transmission of the ground fault current detection value I ₀ and other information transmission to the master station 6.

On the other hand, the master station 6 has an accident information receiving unit 601 and an information transmitting unit 602.
And are provided. The accident information receiving unit 601 collects the accident information from the substation 2, and the ground fault current detection value I ₀ is collected from each slave station 5, 5 ... Perform processing. Reference numeral 604 is a display operation unit such as a CRT or keyboard, and 605 is a recording unit.

Next, the operation of this ground fault point recognition device will be described.

The master station 6 outputs a slave station selection signal and a ground fault current request signal (can be omitted) to each slave station 5, 5 ... And collects the ground fault current detection value I ₀ of each slave station 5, 5 ... . That is, in response to this signal, the corresponding slave station 5 returns the ground fault current detection value I ₀ stored in the maximum value storage unit 505 to the master station 6. When the master station 6 confirms the reception of the ground fault current detection value I ₀ and determines that the slave station 5 does not need to store it, it transmits a reset command signal to the slave station 5, and sends this signal. In response, the slave station 5 initializes the maximum value storage unit 505.

When the ground fault is recognized in the master station 6, the information processing unit 60
3 indicates that the ground fault point is recognized and the ground fault section (ground fault portion)
Is displayed on the CRT and other notification processing is performed to the operation manager of the distribution line. If necessary, the collected data will be recorded, accident recovery procedures will be created, and automatic recovery operations will be performed.

The ground fault current detection value I ₀ is collected in units of feeders, banks, or all slave stations collectively.
... will be sequentially collected. The following may be considered as the timing of collection.

 Regular collection such as daily or monthly.

In this case, all switch points are targeted. By this periodical collection, it is possible to recognize a minor ground fault condition that is not recognized as a ground fault accident.

Automatic collection after receiving ground fault accident occurrence information from substation 2.

In the substation 2, as soon as the DG installed in each feeder operates and the FCB 206 is automatically shut off, ground fault information for each feeder is transmitted to the master station 6 under its jurisdiction.

If the ground fault is discontinuous, the reclosing at substation 2 will be successful. Upon confirming the success of the reclosing, the master station 6 recognizes that this accident is a discontinuous ground fault. The success of reclosing can be confirmed by receiving the information indicating that from the substation 2, but whether the FCB206 re-shutoff occurs within a certain time period in the ground fault recognition device. It is also possible to monitor and judge that the reclosing is successful if it does not occur.

After confirming the success of reclosing, the master station 6 determines that power has been transmitted to all the switch points belonging to the ground fault occurrence feeder,
The ground fault current detection value I ₀ is automatically collected for those switch points to recognize the ground fault point.

Further, when only the OVG 203 of the substation bank operates and the FCB 206 is not automatically shut off, the substation 2 transmits only the operation signal of the OVG 203 to the master station 6. In this case, the master station 6 determines that there is a slight ground fault, automatically collects the ground fault current detection value I ₀ for the switch points belonging to the bank, and recognizes the ground fault point.

 Automatic collection after operator's manual input.

In this case, all switch points designated by the operator or all switch points belonging to a designated bank or feeder are targeted.

The master station 6 recognizes the occurrence of the ground fault from the collected ground fault current detection value I ₀ based on the distribution of the ground fault current in the distribution line 1.

Here, the distribution of the ground fault current flowing through the distribution line when the ground fault occurs will be described.

FIG. 2 shows the distribution of the ground fault current at the time of the ground fault of the distribution line.

Further, even when a slight ground fault condition before the ground fault occurs on the distribution line 1, the slight ground fault current at each switch point of each feeder is smaller than that at the time of the ground fault. , It has the same distribution as at the time of the accident.

Here, it is assumed that the distribution line 1A is divided into sections 1 to 4 by the section switches DM _{1 to} DM ₃ in the section from the substation 2 to the interchange switch, and that a ground fault occurs in the section 2. . At this time, as shown in the equation (1), the ground fault current I _0A flowing through the FCB 206A becomes a combined current of the other FCB 206B ... 206n. However, I _0B and I _0n are currents that flow via the ground capacitances C _B and C _n of the distribution lines 1B and 1n.

I _0A = I _0B + ... + I _0n (1) Further, the currents in the respective portions of the distribution line 1A are similarly expressed by the equations (2) to
As shown in (6), it is a combined current of the currents due to the capacitance to ground in each part. However, I _{M1 to} I _M3 are each switch DM
_{1 to} DM ₃ ground fault current, I _X1 and I _X2 are power source side and load side ground fault currents at ground fault point X, C ₁ , C ₂ and C ₄ are sections 1, 2 and 3 of distribution line 1A. Capacitance to ground at I _C1 , I _C2 and I _C4 are ground fault currents due to ground capacitance C ₁ , C ₂ and C ₄ , and C _3-1 and C _3-2 are sections 2
Earth capacitance of the power supply side and load side of the earth絡点X in, I _C3-1, I _C3-2 is the capacitance to ground C _3-1, a ground fault current by C _3-2.

_{I M1 = I 0A + I C1} ... (2) I M2 = I 0A + I C1 + I C2 ... (3) I X1 = I 0A + I C1 + I C2 + I C3-1 ... (4) I X2 = I C3-2 + I C4 (5) I _M3 = I _C4 (6) That is, in the section switch DM ₂ in the preceding stage of the ground fault point X, FCB206A
The combined current of the current of (1) and the current due to the electrostatic capacitance in the sections 1 and 2 flows. In the section switch DM ₃ in the latter stage of the ground fault point X, the current due to the electrostatic capacitance to ground in the subsequent section 4 flows in the opposite direction.

Further, FIG. 3 shows the distribution of the ground fault current not only for the section switches DM _{1 to} DM ₃ but also for the partial switches D _{1 to} D ₄ installed in each section. Also in this case, the distribution of the ground fault current is the same as that described above. If the slave stations 5, 5 ... Are installed in the partial switch and the ground fault current detection value I ₀ is monitored, the ground fault point can be limited to a narrower range. In the example shown in FIG.
It can be recognized that the ground fault point is in the portion 2 within the section 2.

Thus, a large difference occurs between the ground fault current at the switch point on the power supply side and the ground fault current at the switch point on the load side with the ground fault point X as the boundary. In this embodiment, focusing on this development,
Basically, it is determined whether there is a large difference in the ground fault current detection value I ₀ between the front and rear switch points (hereinafter, this condition is referred to as “judgment condition”), and the judgment result determines the ground fault point. To recognize.

The following four are conceivable as specific examples of the determination condition.

The condition is that the difference between the compared ground fault current detection values I ₀ is the largest and is a certain value or more.

The difference between the detected ground fault current detection values I ₀ is the largest, and the ratio K between the ground fault current detection value I _{0 at} the power supply side switch point and the ground fault current detection value I ₀ at the load side switch point is at least a certain value. Is a condition.

The condition is that the difference between the compared ground fault current detection values I ₀ is the largest, the difference is a certain value or more, and the ratio K is a certain value or more.

 The condition is that both of the conditions are met.

By making the threshold for judgment variable, it is possible to coordinate with the level at which the ground fault relay of the substation operates, and for detecting a slight ground fault, a threshold for detecting a fine ground fault. It is also possible to use a value and use a threshold value for detecting a normal ground fault to detect a normal ground fault.

By the way, the above determination conditions cannot be directly applied to the power supply section or the terminal section where the ground fault current cannot be detected before and after the section. Further, when the feeder includes a section where the load side is branched into a plurality of sections (branch section), this branch section cannot be applied.

Therefore, when the determination target is a non-branch section other than the power supply section and the terminal section, the ground fault currents of the switches before and after the section are compared, and if the determination condition is satisfied, there is a ground fault point in that section, When the determination condition is not satisfied, it is determined that there is no ground fault point in the section (first determination criterion).

Next, the criteria for detecting the ground fault in the power source section, the terminal section and the branch section will be described.

4 to 12 show various examples of ground fault accidents. In these figures, the large forward ground fault current is shown by the solid line,
The small ground fault current in the opposite direction is indicated by the broken line.

As shown in FIG. 4, when a ground fault occurs in the section 1, the ground fault current I _M1 of the switch DM ₁ on the power source side becomes larger than the ground fault point, and the switches DM _{2 to} DM on the load side. ₈ Ground fault current I _M2 ~ I
_M8 has a small value.

Further, as shown in FIG. 5, when a ground fault occurs in section 2 (branch section), the ground fault current I of the switches DM ₁ and DM ₂ on the power supply side is
_M1 and I _M2 have large values, and the ground fault currents I _{M3 to} I _M8 of the switches DM _{3 to} DM ₈ on the load side have small values.

Further, as shown in FIG. 6, when a ground fault occurs in a section on the load side of the branch section 2, for example, section 3, the switchgear
The ground fault currents of DM _{1 to} DM ₃ become large, and other switch DM ₄
The ground fault currents I _{M4 to} I _M8 of ~ DM ₈ are small values.

The difference between the ground fault currents I _Mi and I _Mj of adjacent switches DM ₁ and DM _j is ΔI _ij
Then, when a ground fault occurs in the branch section 2 or the section 1 on the power source side of the branch section 2, the determination conditions are not satisfied for ΔI ₃₅ , ΔI ₃₇ , and ΔI ₅₇ .

On the other hand, when a ground fault occurs in the section 3 on the load side of the branch section 2, the determination conditions are satisfied for ΔI ₃₅ and ΔI _37, but not for ΔI ₅₇ .

Therefore, when the judgment target is the branch section, the ground fault current values of the load side switches in the branch section are compared with each other, and if the judgment conditions are not satisfied for all, the ground fault point is not the branch section or the branch section. If it is in the section on the power supply side and the determination condition is satisfied for any of them, it can be determined that the ground fault is in the section on the load side of the branch section (second determination criterion).

Further, when the ground fault point is located on the load side of the branch section, the ground fault currents of the load side switches are compared with each other, and it can be determined that the ground fault point is on the branch side where the ground fault current is maximum ( Third
Discrimination criteria).

In addition, when a ground fault occurs in branch section 2, ΔI ₂₃ , Δ
I ₂₅ and ΔI ₂₇ satisfy the above judgment conditions, and in the latter case ΔI
₂₅ and ΔI ₂₇ satisfy the judgment condition, but ΔI ₂₃ does not satisfy the judgment condition.

Therefore, with reference to the ground fault current in the switch on the power supply side in the branch section, it is determined whether the ground fault current in the switch on the branch load side satisfies the judgment conditions. It can be determined that the section has a ground fault (fourth determination criterion).

As a result of performing the determination according to the first to fourth determination criteria, when the ground fault is not detected, it is determined that the power supply section or the terminal section has the ground fault.

7 and 8 show an example in which a ground fault exists in the power source section, and FIGS. 9 and 10 show an example in which a ground fault point exists in the terminal section (section 4).

If the ground fault feeder is a system that does not have a switch,
When there is feeder ground fault information, it can be determined that there is a ground fault point in the power supply section.

When the ground fault generating feeder is a system having switches, as shown in FIGS. 7 and 8, if there is a ground fault point in the power source section, the ground fault currents of all the switches DM _{1 to} DM ₈ will be Get smaller.

On the other hand, as shown in FIG. 9 and FIG. 10, when the terminal section is the ground fault section, the ground fault currents of the switches DM _{1 to} DM ₄ are large, and the ground faults of the switches DM _{5 to} DM ₈ are large. The junction current becomes smaller.

Therefore, as shown in FIG. 7 and FIG. 9, when the ground fault generating feeder is a non-branching system, for example, the ground fault current detection value of the switch DM ₄ immediately before the terminal section is compared with a threshold value, It is possible to determine whether the ground fault exists in the power source section or the terminal section by checking the magnitude.

Further, as shown in FIG. 10, when the ground fault occurrence feeder includes a branch section (section 2), in the determination of the branch section, the ground fault occurrence system is specified as the distribution lines on the section 3 and section 4 sides. When it is determined that the section 3 has no ground fault, it can be determined that the section 4 has a ground fault. At this time, similarly to the above, the determination may be made in consideration of the condition that the detected value of the ground fault current is a certain value or more.

When the power supply section is a branch section as shown in FIG. 11, the power supply section is a ground fault section when it is determined by the second determination criterion that the power supply side area has a ground fault section. Can be determined.

By summarizing the above determination criteria, it is possible to configure a ground fault section recognition flow that includes a branch section, a power supply section, and a terminal section as the determination targets. 12 to 14 show one example thereof.

Here, returning to FIG. 1, when detecting the switches 3,3 ... or the switch controllers 4,4 ..., the slave stations 5, 5 ... Detect the ground fault current detection value I _0. May not be possible. In consideration of such a case, there is also a mode in which the mode of use / non-use of ground fault detection is set in the slave stations 5, 5. Ground fault current detection value I ₀
... cannot be detected, the slave stations 5, 5 ... Enter the non-use mode, and when receiving the ground fault current request signal from the master station 6, notify that the ground fault current detection value I ₀ cannot be transmitted.

As a method of this notification, any one of "bit information of ground fault detection non-use mode", "ground fault current detection value unusable flag", and "data format other than predetermined value" is used as the ground fault current detection value I _0.
Instead of or in addition to the ground fault current detection value I ₀ , a mode of transmitting to the master station 6 is conceivable.

Upon receiving the above notification, the master station 6 treats the switches before and after the slave station 5 as one unit, and detects the ground fault current value I _{0 at} the switch points before and after the switch point of the slave station 5. The ground fault point recognition is performed based on.

FIG. 15 shows the structure of the apparatus of another embodiment.

In this embodiment, the slave stations 5, 5 are associated with the switch controllers 4, 4, ...
... Instead of installing (see Fig. 1) switch controller 8,
8 ... Slave station with ground fault current detection function and information communication function
It takes the form of adding the same function as 5,5 .... A switch control circuit 801 controls a known switch control function. The other structure is similar to that of the embodiment shown in FIG.

H. Effects of the Invention As described above, according to the present invention, a ground fault point recognition device is configured from a slave station installed at each switch point of a distribution line and a master station that controls each slave station. , The slave station measures the zero-phase current of the distribution line and transmits the ground fault current detection value to the master station, and the master station receives the ground fault current detection value from each slave station and Based on this, the ground fault section is determined.

In this determination of the ground fault section, by checking the distribution status of the ground fault current detection value, it is possible to target all sections including the power supply section and the terminal section. Even when included in the ground fault feeder,
A ground fault can be recognized.

Therefore, even in the case of a slight ground fault that does not result in the automatic shutoff of the FCB, which was impossible in the past, it is possible to recognize the fine ground fault point due to uninterruption.

In addition, the slave station holds the maximum value of the zero-phase current of the distribution line and sends it to the master station as the ground fault current detection value, so it was difficult to detect it intermittently or discontinuously. It is also possible to recognize a ground fault, and it is possible to take fundamental measures to eliminate the cause of the accident at the ground fault to prevent recurrence, which has a great effect on the maintenance of distribution lines.

Moreover, since the ground fault point can be recognized for each section switch unit or each partial switch unit, there is an advantage that the search for the ground fault point becomes easy.

Further, it is possible to recognize this before the occurrence of the ground fault, that is, even if a slight ground fault that does not lead to the accident occurs. Therefore, there is an advantage that preventive maintenance measures can be taken before the ground fault condition develops into a ground fault accident.

[Brief description of drawings]

FIG. 1 is a block diagram showing a ground fault point recognizing device according to an embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams showing a distribution of a ground fault current when a ground fault occurs, and FIGS. FIG. 11 is an explanatory view showing various examples of ground fault accidents, FIGS. 12 to 14 are flowcharts showing procedures of ground fault section recognition, and FIG. 15 is a ground fault point recognition device according to another embodiment of the present invention. FIG. 16 is a block diagram showing an example of a ground fault accident of a distribution line. 1 ... Distribution line, 2 ... Substation, 3 ... Switch, 303 ... Z
CT, 4 ... Switch controller, 5 ... Slave station, 501 ... Auxiliary C
T, 502 ... Amplifier, 503 ... A / D converter, 504 ... Smoothing operation section, 505 ... Maximum value storage section, 506 ... Slave station information transmission section, 6 ... Master station, 602 ... … Master station information transmission unit, 603 …… Information processing unit, 7 …… Information transmission path, 8 …… Switch controller with built-in slave station functions.

Claims (1)

[Claims] 1. A device comprising a plurality of slave stations installed at respective switch points of a distribution line and a master station for controlling each slave station, and recognizing a ground fault occurrence and a ground fault occurrence section of the distribution line. In the slave station, a zero-phase current detection unit that measures the zero-phase current of the distribution line, and a ground fault current storage unit that stores the maximum value of the detection signal of this zero-phase current detection unit as the ground fault current detection value, A ground fault current detection value transmission unit that transmits the ground fault current detection value to the master station is provided, and the master station has a ground fault current detection value reception unit that receives the ground fault current detection value from each slave station, Based on the ground fault current detection value from each slave station, the ground fault recognition unit that sequentially determines the presence or absence of the ground fault from the power supply side by comparing and determining the magnitude of the ground fault current detection value in units of switches. This ground fault recognition unit determines the non-branch section other than the power source section and the terminal section, and the ground fault current detection value before and after When the difference is large, the non-branch section determination unit that determines that there is a ground fault point in the non-branch section, and the branch section as the determination target, the ground load current detection values on the branch load side are compared with each other, and the difference If all are small, it is judged that there is a ground fault point in the power supply side area, that is, in the branch section or in the section on the power supply side from the branch section, and if any of these differences is large, the load side area In other words, if there is a ground fault area determination unit that determines that there is a ground fault point on any of the branched load sides, and if there is a ground fault point on the power source side area, the ground fault current detection value on the power source side of the branch section. The difference between the ground-fault current detection values on the side of each branch load with respect to is taken.
It is determined that there is a ground fault point in the branch section, and when the difference is small, a branch section determination unit that determines that there is a ground fault point in the section on the power supply side of the branch section; If there is a ground fault point in the area, compare the ground fault current detection values on each branch load side, and determine that the ground fault point is on the load side with the maximum ground fault current detection value. Is determined, and the magnitude of the ground-fault current detection value on the power supply side of the terminal section is determined.If the ground-fault current detection value is larger than a certain value, it is determined that the terminal section has a ground fault point. However, the ground fault point recognizing device for a distribution line is characterized by comprising an end section discriminating unit that judges that there is a ground fault point on the power supply side when the power source side is small.