JP4856886B2 - Ground fault section orientation system - Google Patents

Description

  The present invention relates to a ground fault section locating system that detects in which section of a distribution line a ground fault has occurred using a zero-phase ammeter built in a switch of a distribution automation system.

A transformer in a distribution substation is usually connected to multiple distribution lines, and when a ground fault occurs, a zero-phase current flows uniformly from each distribution line toward the ground fault point (see Figure 2). ), A zero-phase current corresponding to the sum of the ground capacitances of the sections in the direction opposite to the direction of the ground fault point flows through the switch of each distribution line.
For example, in the example of FIG. 2 where a ground fault exists in the section between the first automatic switch and the second automatic switch of the distribution line 1, the second automatic switch of the distribution line 2 includes
Ground fault current at ground fault point x (C _2-2 + C _2-3 + C _2-4 ) / ΣC _nk
Zero-phase current flows.
When the value I of the zero-phase current at the time of the ground fault is expressed by a mathematical formula, it can be estimated as the following mathematical formula (1).

  Conventionally, when the ground capacitance of each section of the distribution line is substantially equal to each other, the ground fault current value flowing through the load-side switch in the ground fault section and the ground fault current value flowing through the power-side switch By utilizing the phenomenon that the difference becomes the largest, the earth fault current data measured by the slave station having the earth fault current measuring function installed on the pillar of the automatic switch is transmitted to the master station via the communication means, and each slave By analyzing the ground fault current data of the station at the master station, the monitoring section where the ground fault current difference between the adjacent automatic switches is maximized is determined as the ground fault section (see, for example, Patent Document 1).

  However, the above-mentioned conventional means does not consider the direction in which the ground fault current flows, and performs the display using only the current amount as information regardless of the direction, so that the ground fault current of the adjacent automatic switch is Even if the section of the combination with the largest difference is determined as the ground fault point, for example, the distribution line tends to have a larger ground capacitance than normal due to the presence of a long cable section in the load side section of the ground fault section, etc. In the case of distribution lines, etc., where there is a section in the environment where a large ground fault current on the load side of the ground fault point with respect to the automatic switch is the same as that on the power supply side, The orientation may be extremely difficult.

  Therefore, a distribution line system having a master station that communicates via a transmission line with a slave station that is paired with a plurality of automatic switches provided on the distribution line, and a ground fault in each distribution line collected from the plurality of slave stations. A distribution line system is devised in which the master station has an arithmetic unit for determining an accident section from the magnitude of the zero-phase current and the phase difference between the zero-phase current and the power supply voltage. For example, the technique disclosed in Patent Document 2 compares the phase difference of the zero-phase current at the time of the ground fault obtained from a plurality of slave stations, and an accident has occurred in a section where the phase difference has greatly changed. That is the system that judges.

Japanese Unexamined Patent Publication No. 7-298486 JP-A-5-80109

  However, as described above, the zero-phase current at the time of the ground fault is greatly affected by the capacitance to the ground. Therefore, it is simply an interval in which the phase difference between the zero-phase current and the voltage in each distribution line greatly changes locally. Inevitably, an example in which a plurality of ground fault sections are derived cannot be avoided. Further, in such a system that simply compares the phase difference of the zero-phase current at the time of the ground fault, a single-line ground fault current compensating reactor (hereinafter referred to as a reactor) is applied to the distribution line in order to suppress the ground fault current, which will be described later. .) Is distributed, there is also a problem that erroneous determination of a section of a distribution line in which a ground fault has not occurred as a ground fault section occurs.

  The reactor functions to suppress a ground fault current by flowing a current having an opposite phase to the ground fault current into the distribution line when a ground fault occurs. The capacity of the reactor installed in each distribution line is limited to a capacity that does not allow a current greater than the ground fault current due to the ground capacitance of each distribution line to operate normally in a ground fault relay at the substation. ing. However, for each section of the distribution line, there may be a case where a reactor larger than the ground capacitance of one section of the distribution line is installed because there is no space for installing the reactor. An example of the above case is shown in FIG. In this case, there is a section in which the phase of the zero-phase current at the time of ground fault changes greatly in the distribution line with the reactor installed even though the ground fault has occurred in other distribution lines. It will be erroneously determined.

  In view of the actual situation of the ground fault phenomenon that is greatly affected by the presence of the ground capacitance and the presence of the reactor as described above, the present invention determines the appropriate ground fault point according to the various environments where the distribution lines are placed. It is intended to provide an accurate and simple ground fault section location system that can be performed.

  The ground fault section locating system according to the present invention made to solve the above problems is a zero-phase current detection means and a power supply voltage detection means installed as a pair at each monitoring point of a distribution line each equipped with an automatic switch. And the presence or absence of a ground fault by comparing the magnitude of the zero phase current taken from the distribution line by the zero phase current detection means of each monitoring point with a predetermined threshold level, and when determining a ground fault The zero-phase current value and the ground-fault detector that synchronizes and stores the power-supply voltage immediately before it is determined to be a ground fault, and the power-supply voltage and zero-phase that are stored by the ground-fault detector at each monitoring location that has been determined to be a ground fault The ground fault phase deriving unit for deriving the direction of the ground fault phase and the ground fault point at each monitoring point from the phase difference with the current, and the monitoring based on the direction of the ground fault phase and the ground fault point guided by the ground fault phase deriving unit. With an orientation section that guides the ground fault section from the sections before and after the location And wherein the door.

  For the slave station on the most power supply side of each distribution line, the orientation part has a zero-phase current sign (-) when the direction of the ground fault point is the power supply side, and the direction of the ground fault point is the load side Is obtained by adding the signs of zero-phase current as (+) to obtain the sum of currents concentrated in the section, 1-CL / C (CL: reactor installed in one section of the distribution line It is also possible to have a flow rate calculation module that performs a correction process that takes an absolute value of a value obtained by multiplying the ground capacitance by C, C: the ground capacitance of the entire distribution line connected to the same transformer) .

  In the power supply voltage, it is necessary to clearly grasp the sampling phase of the power supply voltage during processing because the power supply voltage used when locating the ground fault section can take various types depending on the difference in the sampling phase. Become. Then, even if the sampling phase of the power supply voltage is different for each monitoring location, if the orientation process with appropriate phase correction according to the difference in the sampling phase is set for each monitoring location, the monitoring location It is possible to accurately derive the ground fault phase and the ground fault point of the common reference that can be compared between the monitoring points every time.

  As the processing mode of the orientation unit, for example, based on the zero phase current value held by the ground fault detection unit and the direction of the ground fault phase and the ground fault point guided by the ground fault phase deriving unit, A processing form in which a section having the largest sum of zero-phase currents concentrated in the sandwiched section is determined as a ground fault section. As a system configuration, the zero-phase current detection means, the power supply voltage detection means, the ground fault detection unit, and the slave station including the ground fault phase deriving unit and the master station including the orientation unit are connected by a communication line. A ground fault section orientation system consisting of The communication line may be either a wired line or a wireless line.

  The present invention is based on the magnitude of the zero-phase current and the phase difference between the power supply voltage and the zero-phase current, and whether the ground fault phase and the ground fault point exist on the power source side or the load side of the monitoring location (the ground fault point By using a method for locating the ground fault section based on the appropriate orientation requirement based on the determination result for the orientation), even if the ground fault section is a ground fault on the power source side of the first automatic switch, In addition to being able to accurately pinpoint the fault section, even if a zero-phase current of the same level as the automatic switch on the power supply side flows through the automatic switch on the load side of the ground fault point, the fault section is correct. Orientation is possible.

  In addition, considering the actual situation of the distribution line that the zero-phase current concentrated in the ground fault section is clearly larger than the zero-phase current flowing out by the reactor, the sum of the zero-phase current concentrated in the section between adjacent monitoring points Since the evaluation including the influence of the reactor is made by comparing the two, even if there is a reactor on the distribution line, a plurality of ground fault locations are not led and an accurate orientation can be realized.

Hereinafter, an embodiment of a ground fault section orientation system according to the present invention will be described with reference to the drawings.
In this example, an automatic switch provided in each distribution line is appropriately provided with a zero-phase ammeter (ZCT) built in the automatic switch, and a slave station that detects a signal from the zero-phase ammeter, The slave station is provided with zero-phase current detection means 1, power supply voltage detection means 2, calculation means 7, and communication means 8, and data relating to a ground fault measured by the slave station (hereinafter referred to as ground fault data). .) Is transmitted to the master station via the communication means 8, and the ground fault interval is determined by analyzing the ground fault data of each slave station at the master station (see FIG. 1).

  In this example, the zero-phase current detecting means 1 of each slave station uses a single ZCT built in the automatic switch for the purpose of detecting a zero-phase current at the time of a ground fault. The zero-phase currents are collectively sampled and output to the ground fault detector of the arithmetic means 7 via a signal cable. For example, in a method in which an ammeter (CT) is attached to each of the three phases of the distribution line and the current of each phase is measured and the ground fault current is calculated by combining them, the zero-phase current is not limited to a ground fault. This is because there are many cases of erroneous detection. The sampling of the zero-phase current is performed while removing AC component noise through a filter or the like. The power supply voltage detection means 2 of each slave station always samples a power supply voltage between two predetermined phases (hereinafter referred to as a power supply voltage between two phases) determined for each slave station, and uses a transformer. The voltage is stepped down (for example, 6600V to 100V) and output to the calculation means 7.

The calculation means 7 includes a ground fault detection unit 3 and a ground fault phase deriving unit 4.
The ground fault detection unit 3 integrates the zero-phase current value for each predetermined amount of data (for example, the number of samplings) and determines whether the reference threshold level is exceeded. In addition, it is determined whether or not the duration time exceeding the threshold level exceeds the reference threshold time, and when it is determined that it has exceeded, it is positioned as the occurrence of a ground fault, and when the ground fault is determined The maximum value of the zero-phase current (hereinafter referred to as the maximum current) and the power supply voltage between the two phases immediately before judging the ground fault accident sampled in synchronization with the sampling of the maximum current (hereinafter referred to as the immediately preceding power supply voltage). .).

  As described above, the calculation means 7 that has collected the maximum current and the immediately preceding power supply voltage calculates the ground fault phase ("R", "S", "T") and the ground fault point from the phase difference between the maximum current and the immediately preceding power supply voltage. The direction (“+” when the ground fault phase is on the load side of each automatic switch, “−” when the ground fault phase is on the power source side of each automatic switch) is derived.

  The detection of the ground fault phase is performed by the ground fault phase deriving unit, and after confirming in advance the two phases from which the previous power supply voltage is sampled, only the fundamental frequency of the power supply frequency is obtained for the previous power supply voltage and the maximum current. A waveform that has passed through the band-pass filter to be extracted is processed. That is, arithmetic processing is performed to perform Fourier transform on the first harmonic by the following mathematical formulas (2) to (7) and to calculate the phase of those vectors. There is also a method of obtaining from the time difference of the point where the immediately preceding power supply voltage after passing through the band-pass filter and zero of the maximum current waveform intersect.

  The reason for confirming the phase is that when the phase of the vector is calculated, the phase difference between the immediately preceding power supply voltage and the maximum current is naturally different depending on the difference in the sampling phase of the immediately preceding power supply voltage. This is because it is necessary to correct in any of the following when performing the process by the ground fault phase deriving unit. For example, when the power supply voltage is collected from the R-S phase and from the S-T phase and the T-R phase, it is necessary to include the amount advanced by +240 degrees and the amount advanced by +120 degrees, respectively.

  The ground fault phase deriving unit 4 of the calculation means 7 calculates the phase difference between the vector of the maximum current and the immediately preceding power supply voltage as described above, and the phase in which the immediately preceding power supply voltage is sampled and the actual state of the distribution line. A table in which the requirements of the phase difference are associated with the ground fault phase and the direction of the ground fault point is derived, and the direction of the ground fault phase and the ground fault point is derived based on the table.

  In general, when a ground fault occurs in a distribution line, a zero-phase current flows in the ground fault circuit using the phase voltage of the ground fault phase (3.810 V, but the phase is 180 degrees different from the normal power source) as the power source. . The ground fault circuit can be simplified as a circuit having only a ground capacitance and a ground fault resistance (see FIG. 3). When calculated based on the simplified ground fault circuit, in a normal distribution system (the ground capacitance of the entire distribution line connected to the same transformer is about 9 μF), when the ground fault resistance is 200Ω or more, When the ground fault point is on the load side of the monitoring location, the phase of the zero-phase current at the time of the ground fault is in a range advanced from about 180 degrees to 240 degrees with respect to the phase of the ground fault phase voltage. In addition, since the phase of the zero-phase current at the time of the ground fault is 180 degrees different between the power supply side and the load side of the ground fault point, on the opposite side across the ground fault point, the phase of the ground fault phase voltage is about 0 to 60 degrees. The phase of the zero-phase current at the time of the ground fault exists within the advanced range (see FIG. 4).

  For example, the following Table 1, Table 2, and Table 3 show the case where the immediately preceding power supply voltage and the zero-phase current at the time of ground fault are collected when the power supply voltage is R-S phase, ST phase, and TR phase, respectively. It shows the ground fault phase derivation requirements. The table referred to in the process of deriving the direction of the ground fault phase and the ground fault point includes the phase difference shown in the left column of the table and the direction of the ground fault phase and the ground fault point shown in the right column. For example, when a ground fault point exists on the load side of each automatic switch due to an R-phase ground fault, the maximum current phase is 150 degrees with respect to the power supply voltage immediately before the RS phase. The actual state of the distribution line is reflected in the process, such as a range of ~ 210 degrees (see FIG. 4).

  As for the direction of the ground fault phase and ground fault point introduced by each slave station, the ground fault waveform may appear in a form other than a sine wave depending on the ground fault situation, and the ground fault resistance is extremely small In some cases, the ground fault data indicating two or more ground fault phases as a ground fault section from a plurality of slave stations provided on the distribution line as a result of the phase of the maximum current further proceeding than the power supply voltage. May be sent out.

  In such a case, all the ground fault data transmitted to the master station will indicate the same phase as the ground fault phase, with the ground fault phase of the monitoring location that detected the maximum ground fault current as the target. In addition, a pre-processing unit that appropriately performs ground fault phase correction processing that attempts to adjust the phase difference within ± 60 degrees on the ground fault data of each slave station may be provided in the determination means. This is substantially equivalent to appropriately shifting the determination of the direction of the ground fault phase and the ground fault point led by each slave station to the determination of one step above or one step below in Table 1. To do.

  When each of the slave stations detects the occurrence of the ground fault as described above, the ground current including the maximum current and the immediately preceding power source voltage collected as described above, and the ground fault phase and the data indicating the direction of the ground fault point are included. The fault data is constituted and ground fault data indicating that a ground fault has occurred in the master station is transmitted to the master station through the communication means 8 and a wired or wireless communication network. In this example, for the slave station that does not detect the occurrence of a ground fault, ground fault data is not sent to the master station.

  The ground fault phase deriving unit 4 performs the ground fault shown in the above table as an example when the ground capacitance of the entire distribution line connected to the same transformer is 9 μF and the ground fault resistance is 200Ω or more. The direction of the ground fault phase and the ground fault point can be derived relatively accurately by the phase derivation requirements, but when the ground fault resistance is less than 200Ω, the ground fault resistance (Rg) is estimated from the maximum current, and the ground fault In some cases, the accuracy may be increased by performing the process of correcting the orientation of the phase and the ground fault point in the orientation unit 6.

  At that time, the orientation unit 6 determines the advance (Ф) of the phase of the ground fault current for Rg calculation with respect to the ground fault resistance (Rg) and the ground fault phase voltage (3.810 V) at that time (9) (9) Derived by the arithmetic processing by

  In addition, the calculation process which calculates | requires the ground fault current for ground fault resistance (Rg) calculation by the said orientation part 6 is performed as follows.

  The orientation unit 6 determines that the ground fault resistance (Rg) is small when the phase advance (Ф) of the ground fault current for Rg calculation derived as described above exceeds 60 degrees. The ground fault phase and the ground fault direction data from each slave station are corrected in such a manner that a calculation process of subtracting 30 degrees from the phase difference is performed. In addition, referring to the phase in which the immediately preceding power supply voltage is sampled and the phase difference requirement in accordance with the actual condition of the distribution line as described above, the ground fault phase, and the direction of the ground fault point are referred to, and based on the table. To derive the direction of the ground fault phase and the ground fault point. In addition, even if correction | amendment when the said ground fault resistance is small, if the data regarding the change point of a ground fault direction are used, the ground fault area can be determined.

  The master station is composed of a communication unit 9 and a determination unit 10, and the magnitude of the maximum current (zero phase current at the time of ground fault) received through the communication unit 9, the ground fault phase, and the ground fault point The ground fault data relating to the direction and the ground fault data with the correction as described above are used, and based on the ground fault phase and the direction of the ground fault point by the orientation unit 6 of the determination means 10. For example, orientation processing including narrowing down processing to a single ground fault section is performed based on the orientation procedure shown in FIG. 7 (see FIG. 7).

  The narrowing-down process in this example is based on the zero phase current value held by the ground fault detection unit of the slave station and the direction of the ground fault phase and the ground fault point guided by the ground fault phase deriving unit by the orientation unit 6. The section having the largest sum of the zero-phase currents concentrated in the section sandwiched between the monitoring locations is determined as the ground fault section.

  In this example, both ground faults are detected when the direction of the ground fault point determined by a slave station that has detected a ground fault (hereinafter referred to as a ground fault detection station) is equal between two adjacent ground fault detection stations. If the difference between the zero-phase currents of the stations is different and the direction of the ground fault point is different, calculate the sum of the zero-phase currents of the two ground fault detection stations to obtain two or more adjacent ground faults including the branch section. The flow rate calculation module 11 calculates the sum of currents concentrated in all the sections sandwiched between the detection stations.

  In some cases, the zero phase current of the non-ground fault detection station is zero (zero) for two adjacent slave stations including all the slave stations other than the ground fault detection station (hereinafter referred to as non-ground fault detection stations). As for the direction of the ground fault point: None), as in the previous calculation process, zero concentrated in all sections sandwiched between two or more adjacent ground fault detection stations and non-ground fault detection stations including the branch section The sum of the phase currents may be obtained by the flow rate calculation module 11.

  According to the narrowing-down process, the ground fault point in the distribution line can be accurately determined even if the reactor exists in the distribution line. However, only by comparing the sum of the zero-phase currents concentrated in each section derived as described above, for example, in the case where the ground fault detection station exists only in a single distribution line, the following problem in orientation Occurs.

  The zero-phase current detected at each slave station during a ground fault decreases as the ground fault resistance increases (see Equation 1). For this reason, when the ground fault resistance is relatively large, the slave station existing on the power source side of the ground fault section in the distribution line including the ground fault section becomes a zero phase current obtained by adding the zero phase currents from other distribution lines. Therefore, although it becomes a ground fault detection station, since the zero-phase current is small in the most power source side slave stations of other distribution lines, it is conceivable that none of them is a ground fault detection slave station. In this case, the zero phase current in the most power supply side slave station of the distribution line including the ground fault section becomes the total sum of the zero phase currents concentrated in the most power supply side section. For example, in the example of FIG. As a result, the zero-phase current sandwiched between the first slave station and the second slave station is smaller than the zero-phase current concentrated in the most power-supply side section, which causes a problem that the most power-supply side section is erroneously determined as a ground fault section.

  Therefore, when the correct ground fault point is required for the section on the most power supply side (hereinafter referred to as the most power supply side) as shown in FIG. It is necessary to perform arithmetic processing.

  That is, when calculating the sum of concentrated zero-phase currents for the most power-supply side section, the sign of the zero-phase current is assigned to the slave station on the most power-supply side of each distribution line in the case of the power supply side facing the ground fault point. When the direction of the ground fault point is on the load side, the sum of the currents concentrated in the section is obtained by performing a process of adding them with the sign of the zero-phase current as (+), and further calculating the calculation A correction value obtained by performing a correction process that takes the absolute value of a value obtained by multiplying the value derived from (1−CL / C) by the flow rate calculation module 11 is obtained, and the narrowing process is performed using the correction value. . In addition, CL is a part for earth capacitance subtraction by the reactor installed in one section of the distribution line, and C is the earth capacitance of the whole distribution line connected to the same transformer (see FIG. 7). ).

  According to the calculation process of the zero-phase current concentrated in the most power source section by the flow rate calculation module 11, even if a ground fault occurs in the most power source side section, the total sum of the zero phase currents concentrated in the most power source section. Compared to the above, since the total sum of the zero-phase currents concentrated in each section of each distribution line other than the ground fault section is remarkably small, the correction process does not adversely affect the orientation of the ground fault section.

  The arithmetic processing is sequentially performed for each section sandwiched between each slave station in the distribution line, and based on the total zero-phase current calculated for each section and the correction value, all the sandwiched between ground fault detection stations Among the sections or all sections sandwiched between all slave stations including non-ground fault detection stations, the sum of the zero-phase currents or the correction value is the largest, and the zero-phase currents are most concentrated. It is possible to perform accurate orientation by selecting a section to be grounded as a ground fault section.

  In the example of FIG. 6 (A), 0.9A-0.8A = 0.1A in the section sandwiched between the first slave station and the second slave station, sandwiched between the second slave station and the third slave station. The zero-phase currents of 0.8A-0A = 0.8A and the 0.9A × 0.75 = 0.675A are concentrated in the section on the power supply side of the first slave station. The section between the second slave station and the third slave station having the largest value is determined as the ground fault point.

  In the example of FIG. 6B, 1.9A−0.2A = 1.7A is sandwiched between the first slave station and the second slave station, and sandwiched between the second slave station and the third slave station. 0.2A + 0.2A = 0.4A in the divided section, 0.2A + 0A = 0.2A in the section sandwiched between the third and fourth slave stations, and (1.9A in the most power source section) -0.3A-0.3A-0.3A) × 0.75 = 0.75A of zero-phase currents are concentrated, and the largest value among the first and second slave stations The sandwiched section will be determined as the ground fault point.

  In the example of FIG. 6C, the section sandwiched between the first slave station and the second slave station is 1.0A + 0.7A = 1.7A, sandwiched between the second slave station and the third slave station. 0.7A-0.4A = 0.3A in the section, 0.4A-0.2A = 0.2A in the section sandwiched between the third and fourth slave stations, the load of the fourth slave station The zero-phase current of 0.2A is concentrated in the section on the side and (1.0A-0.2A-0.2A-0.3A) x 0.72 = 0.216A is concentrated in the section on the most power source side. The section between the first slave station and the second slave station having the largest value is determined as the ground fault point.

  The present ground fault section locating system can flexibly correspond to various distribution line configurations based on the data on the magnitude of the zero phase current at the time of the ground fault and the direction of the ground fault phase and the ground fault point. By further improving the quality of the hardware resources etc. that make up the distribution line, there is a possibility that a more precise ground fault section can be realized.

It is a functional block diagram which shows the embodiment example of the ground fault area location system by this invention. It is a circuit diagram which shows an example which simplified the distribution line. It is a circuit diagram which shows an example which simplified the ground fault circuit. It is explanatory drawing which shows an example of the phase relationship of a power supply voltage and a ground fault current. It is a circuit diagram which shows an example which simplified the distribution line. It is a circuit diagram which shows an example which simplified the ground fault circuit. It is a flowchart which shows an example of the orientation process in the ground fault area orientation system by this invention.

Explanation of symbols

1 zero phase current detection means, 2 power supply voltage detection means, 3 ground fault detection section, 4 ground fault phase deriving section,
6 orientation unit, 7 computing means, 8 communication means (slave station), 9 communication means (master station),
10 determination means, 11 flow rate calculation module,

Claims (4)

Zero-phase current detection means (1) and power supply voltage detection means (2) installed in pairs at each monitoring point of the distribution line each equipped with an automatic switch,
The magnitude of the zero-phase current taken from the distribution line by the zero-phase current detection means (1) at each monitoring point is compared with a predetermined threshold level to determine the presence or absence of a ground fault and to determine a ground fault. A ground fault detection unit (3) for synchronously storing the value of the zero phase current at the time of the power supply and the power supply voltage immediately before the determination of the ground fault,
Deriving the ground fault phase that leads the direction of the ground fault phase and the ground fault point at each monitored location from the phase difference between the power supply voltage and the zero-phase current stored by the ground fault detection unit (3) at each monitored location determined as a ground fault accident Part (4),
An orientation section (6) for deriving a ground fault section from sections before and after the monitoring location based on the direction of the ground fault phase and the ground fault point led by the ground fault phase deriving section (4);
A ground fault section orientation system.   Based on the zero-phase current value held by the ground fault detection unit (3) and the direction of the ground fault phase and the ground fault point guided by the ground fault phase deriving unit, the zero phase current concentrated in the section between the monitoring points The ground fault section orientation system according to claim 1, further comprising an orientation section (6) that locates a section having the largest sum of the two as a ground fault section.   For the slave station on the most power supply side of each distribution line, the sign of the zero-phase current is (-) when the direction of the ground fault point is the power supply side, and the zero-phase current when the direction of the ground fault point is the load side The sum of currents concentrated in the section is obtained by performing a process of adding them with (+) as the sign of 1−CL / C (CL: ground capacitance by the reactor installed in one section of the distribution line Subtracting part, C: The orientation unit (6) provided with a flow rate calculation module (11) for performing a correction process for taking an absolute value of a value obtained by multiplying by the capacitance of the entire distribution line connected to the same transformer) The ground fault section orientation system according to any one of claims 1 and 2, further comprising:   A slave station comprising the zero-phase current detection means (1), a power supply voltage detection means (2), a ground fault detection section (3), and a ground fault phase deriving section (4), and the orientation section (6) The ground fault section locating system according to any one of claims 1 to 3, wherein the master station is connected to the master station via a communication line.

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