JP4373518B2 - Reference time correction method and fault location system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reference time correction method and a fault location system. More particularly, the present invention relates to a reference time correction method for making the reference time accurate, and a failure point locating system capable of accurately locating a failure location by accurately obtaining a surge detection time.
[0002]
[Prior art]
Conventionally, when a failure occurs in the middle of a transmission / distribution line in a transmission line or distribution line (hereinafter referred to as “transmission / distribution line”), the surge detection time at two slave stations sandwiching the failure point There is known a method for obtaining a failure position on a transmission / distribution electric line from the difference between them (Japanese Patent Publication No. 63-51274). In such a method, the localization accuracy at the time when a surge is detected in each of the slave stations at both ends (hereinafter referred to as “surge detection time”) affects the localization accuracy of the fault location.
[0003]
The surge detection time is often obtained by using a reference clock and GPS radio waves provided in each slave station.
Many of these reference clocks use temperature-compensated crystal oscillators or crystal oscillators with high-temperature tanks, and have excellent timing errors with little influence from temperature changes, etc., but errors accumulate over a long period of time. Therefore, it cannot be ignored for surge detection. (See FIG. 9).
[0004]
Therefore, synchronization of the reference time between the slave stations using GPS radio waves is performed. This GPS radio wave is a radio wave emitted by an artificial satellite in GPS (Global Positioning System, Global Positioning System). The GPS is a system that receives radio waves from a plurality of artificial satellites and obtains a position from a difference in time required for the reception. For this reason, a synchronization signal subjected to highly accurate time management is transmitted, and this synchronization signal has very little time error due to the region in the long term.
[0005]
[Problems to be solved by the invention]
However, as shown in FIG. 8, each sync signal has an error such as advance or delay within a certain range. For this reason, if the reference clock is simply adjusted by the synchronization signal, the time becomes inaccurate and is not suitable for use as the surge detection time.
Further, when a state in which GPS radio waves cannot be received due to a reception failure or the like, the time cannot be detected, and the fault point location function cannot be performed.
[0006]
The present invention solves such a problem, and a method for correcting a reference time capable of always obtaining an accurate surge detection time, and a fault location can be determined by obtaining an accurate surge detection time. An object is to provide a possible fault location system.
[0007]
[Means for Solving the Problems]
The reference time correction method according to the first aspect of the present invention is a reference time correction method used as a detection time of a surge voltage or surge current due to a failure occurring in any part of a transmission / distribution line, and is obtained from a received GPS radio wave. The difference between the standard time held by the GPS and the reference time when the standard time is obtained is calculated, and after accumulating the difference for a certain period, the average value of the stored difference is added to the reference time. It is characterized by correcting.
[0008]
The failure point locating system according to the second aspect of the present invention includes a slave station (1) installed in a transmission / distribution electric line and transmitting information on surge detection time to the master station (2), and a failure point based on the information on the surge detection time. A fault location system having a master station (2) for positioning the GPS, and the slave station (1) has a GPS standard time obtained from the received GPS radio wave and a time when the standard time is acquired. After obtaining the difference in the reference time and accumulating the difference for a certain period, the reference time is corrected by adding the average value of the stored difference to the reference time, and a failure occurred in any part of the transmission and distribution line The detection time of the surge voltage or surge current is obtained from the reference time and transmitted to the master station (2) through the communication network.
[0009]
As shown in the third invention, the master station (2) has the surge detection time t1 of one slave station of the pair of slave stations sandwiching the failure point of the transmission / distribution electric wire network, and the above-mentioned Based on the surge detection time t2, the surge propagation speed v, and the length L of the transmission / distribution line between the slave stations, the distance L1 on the transmission / distribution line from the one slave station to the failure point Is obtained from the equation L1 = (L + (t1−t2) × v) / 2.
[0010]
Further, as shown in the fourth invention, the master station (2) has the surge detection time t1 of the slave station closest to the power supply end of the transmission / distribution power line network and the surge of the slave station at the end of the transmission / distribution power line network. Based on the detection time t2, surge propagation speed v, and length L of the transmission / distribution line between the slave stations, the distance on the transmission / distribution line from the slave station on the power source side to the failure point L1 is obtained from the equation L1 = (L + (t1−t2) × v) / 2, and the surge detection time of one slave station of the pair of slave stations sandwiching the failure point position obtained by the above calculation is further obtained. Based on t3, the surge detection time t4 of the other slave station, the propagation velocity v of the surge, and the length L ′ of the transmission / distribution line between the pair of slave stations, The distance L3 on the transmission / distribution line to the failure point is obtained from the equation L3 = (L ′ + (t3−t4) × v) / 2.
[0011]
[Action]
The standard time synchronization signal (hereinafter referred to as the synchronization signal) output from the GPS receiving means is output with an error within a certain range with respect to the world standard time as an absolute reference because each signal is not accurate. For example, in the case of a GPS receiver that outputs a synchronization signal every time the standard time second changes, the error of the synchronization signal with respect to the standard time is collected for a certain period (for example, one day), and the data is aggregated into a graph. Then, a normal distribution graph as shown in FIG. 8 is obtained, and it can be seen that an error occurs in a certain range.
[0012]
However, what should be noted here is that the error of the synchronization signal does not vary within a certain range, but the total result of the error becomes a normal distribution centering on the position where the error from the standard time is zero. That is, since the average value of the total data is the center of the normal distribution graph, it means that the error from the standard time is zero.
From this, the synchronization signal of the GPS receiver has an error in the range of about 200 ns when viewed in a short time such as 1 second with respect to the standard time, but in the average value in a period of one day or one week, It can be seen that the error has the property of approaching zero as much as possible.
[0013]
Next, a reference time signal output from the oscillation circuit. Usually, in order to obtain a stable and accurate reference time signal, a temperature-compensated crystal oscillator or a thermostat crystal oscillator is used as the oscillator.
These oscillators are very stable against changes in ambient temperature, and the reference time signal is advanced or delayed in a short period (eg, 1 second, 1 minute, 1 day, 1 week, etc.). It is possible to easily obtain accuracy that can be said to have almost no fluctuation. However, on the other hand, since a minute time error of the reference time signal is accumulated, a large reference time accumulated error is generated over a long period of time (for example, 1 year or 10 years).
[0014]
As a representative example, FIG. 9 shows a time-dependent change characteristic graph of the reference time signal frequency output from the thermostatic bath crystal oscillator. As shown in FIG. 9, almost no error is observed in a short period, but the error is so large that it cannot be ignored by accumulating minute time errors over a long period of time.
[0015]
Therefore, the time generated by the reference time signal of the oscillation circuit is set as the reference time, and the reference time is corrected with the average value of the error between the reference time and the standard time when the synchronization signal accumulated for a certain period is received. That is, the time accuracy can be maintained by adding the time difference between the reference time signal and the reference time when the synchronization signal is received (see FIG. 6). Also, as shown in FIG. 7, by performing this correction periodically, the error can be kept in a narrower range than when correction is not performed.
As described above, it is possible to always obtain an accurate standard time by periodically correcting the reference time based on an average value of errors between the reference time and the standard time when the synchronization signal accumulated for a certain period is received. Further, each slave station detects a surge at an accurate standard time and transmits it to the master station at an accurate surge detection time, whereby the failure point of the transmission / distribution electric line can be accurately obtained.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
〔Example〕
(1) Configuration of fault location system
As shown in Fig. 1, this fault location system is installed in each of the towers and utility poles of power transmission and distribution lines, and in power company sales offices and branches. It consists of a master station 2 that locates the failure point.
[0017]
(A) Slave station
As shown in FIG. 2, the slave station 1 includes a GPS antenna 111, a GPS receiver 112, an oscillation circuit 121, a reference clock 122, a reference time holding circuit 123, a ZCT 131 (zero phase current transformer), A filter circuit 132, a surge signal detection circuit 133, a surge detection time holding circuit 134, a central processing unit 141, and a communication interface 142 are provided.
[0018]
The ZCT 131, the filter circuit 132, the surge signal detection circuit 133, the surge detection time holding circuit 134, and a part of the central processing unit 141 correspond to the “surge detection means 13”. The central processing unit 141 and the communication interface 142 correspond to the “surge information transmitting unit 14b”.
[0019]
As a similar concept, the GPS antenna 111 and the GPS receiver 112 can be collectively regarded as “GPS receiving means 11”, and the oscillation circuit 121, the reference clock 122, and the reference time holding circuit 123 are collectively referred to as “ It can be regarded as the time measuring means 12 ”.
[0020]
Hereinafter, each component will be described.
(I) ZCT131 (zero phase current transformer)
A surge signal (surge current) generated at the time of failure is detected and sent to the filter circuit 132. When detecting a surge voltage as a surge signal, a voltage detector such as PT or PD is used.
(Ii) Filter circuit 132
Unnecessary commercial frequency signal components other than the surge signal are removed from the signal detected by the ZCT 131, and only the surge signal is allowed to pass through to the surge signal detection circuit 133.
(Iii) Surge signal detection circuit 133
When the level of the surge signal is detected and the signal level exceeds the surge approval level, it is determined that a surge has occurred and a time holding signal is output to the surge detection time holding circuit 134.
[0021]
(Iv) Surge detection time holding circuit 134
When a time holding signal is output from the surge signal detection circuit 133, the time of the reference clock 122 at that time is held and is output to the central processing unit 141 as the surge detection time.
[0022]
(Vi) GPS antenna 111 and GPS receiver 112
The GPS antenna 111 receives radio waves from GPS satellites and sends them to the GPS receiver 112. Then, the GPS receiver 112 extracts the standard time information held by the GPS satellite from the radio wave as a synchronization signal and outputs it to the reference time holding circuit 123.
(Vii) Reference time holding circuit 123
When the synchronization signal is received from the GPS receiver 112, the reference time of the reference clock 122 at the time of reception is held, and this reference time is output to the central processing unit 141.
[0023]
(Viii) Reference clock 122
The reference time is output to the reference time holding circuit 123 and the surge detection time holding circuit 134.
(Ix) Oscillation circuit 121
A reference time signal for measuring time is output to the reference clock 122.
[0024]
(X) Central processing unit 141
The surge detection time output from the surge detection time holding circuit 134 is transmitted to the master station 2 via the communication interface 142. Further, the reference time received from the reference time holding circuit 123 is collected for one day as time error data with respect to the standard time, an average error value with respect to the standard time is obtained from the error data, and the value is used as a correction value as a reference clock. In addition to the time 122, a reference time correction process 124 for correcting the reference time is performed.
(Xi) Communication interface 142
Communication signals are relayed between the central processing unit 141 and the public line network so that the central processing unit 141 can communicate with the master station 2 using the public line network.
[0025]
(B) Master station
Further, as shown in FIG. 3, the master station 2 includes a communication interface 21, an auxiliary storage device 222, a central processing unit 23, a CRT 241, a printer 242, and a keyboard 25.
[0026]
Here, the communication interface 21 can be positioned as a slave station surge information receiving means 21b for receiving information on the surge detection time from each slave station.
Then, the central processing unit 23 can be positioned as failure position specifying means 23c for locating the failure position based on the surge detection time.
[0027]
Further, the CRT 241 and the printer 242 can be positioned as information output means 24 that outputs the orientation result. The keyboard 25 can be positioned as input means.
Each component will be described below.
[0028]
(I) Communication interface 21
The communication signal with the slave station 1 is relayed. That is, the signal sent from the slave station 1 via the public line network is converted and passed to the central processing unit 23.
[0029]
(Ii) Central processing unit 23 (personal computer, workstation, etc.)
Each slave station 1, 1, 1,. . . The position information and surge detection time sent from are received via the communication interface 21 and a fault location process described later is performed.
The failure point obtained by the failure point locating process is output to the CRT 241 or the printer 242 together with the transmission / distribution line diagram data stored in the auxiliary storage device 222.
[0030]
(Iii) Auxiliary storage device 222 (such as a hard disk)
Each slave station 1, 1, 1,. . . The surge detection time and position information sent from the central processing unit 23, the failure points calculated by the central processing unit 23, and transmission / distribution line diagram data necessary for processing in the central processing unit 23 are recorded and stored.
Here, the transmission / distribution line diagram data includes position data of power poles and steel towers, distance data between power poles (steel towers), and the like.
(Iv) Printer 242
In accordance with an instruction from the central processing unit 23, transmission / distribution line diagram data sent from the central processing unit 23, a fault location determination result, and the like are printed.
[0031]
(V) CRT 241
In response to an instruction from the central processing unit 23, a transmission / distribution line diagram sent from the central processing unit 23, a fault location determination result, and the like are displayed.
(Vi) Keyboard 25 (input means)
Input drawing data etc. necessary to create a transmission and distribution line diagram.
Here, the drawing data includes position data of power poles and steel towers, distance data between power poles (steel towers), and the like.
[0032]
(2) Reference time correction processing
A method for correcting the reference time performed in the reference time correction process 124 will be described below.
(1) When the power of the slave station is turned on and the synchronization signal and the standard time data are output from the GPS receiver 112, the central processing unit 141 receives the standard time data from the GPS receiver 112. The time data is set in the reference clock 122 as the reference time, and the time measured by the reference clock 122 is set to the standard time.
[0033]
(2) If the synchronization signal output by the GPS receiver 112 is output, for example, every second, the time of the reference clock 112 is held in the reference time holding circuit 123 according to the synchronization signal every second. Therefore, the time is taken into the central processing unit 141. At the same time, since the standard time data is output from the GPS receiver, the standard time data is also fetched, and the difference between the standard time and the reference time (−ε0, −ε1,. Store as data (see FIG. 5).
[0034]
(3) The time error data is collected at a stage where a certain amount, for example, one day has been collected, and the average value of the time error data is calculated. Since this average value is an actual error between the reference time and the standard time (see FIG. 6), it is added to the measurement time of the reference clock. As a result, the time of the reference clock is corrected to the standard time.
[0035]
According to this method, the advantage of the reference time signal output from the oscillation circuit (there is almost no short time error) and the advantage of the synchronization signal output from the GPS receiver (the average value of the long time error approaches the standard time). ), And a reference time that is stable for both a short time and a long time (long term) and has a small error from the standard time can be obtained. Therefore, almost no synchronization deviation of the reference time with each slave station can be eliminated, so that the difference in surge detection time can be accurately detected, and the fault location accuracy can be increased.
[0036]
(3) Processing in the fault location system
Below, the procedure for specifying a failure location when a failure occurs in the transmission and distribution line will be described. First, in (a), the location of the surge detection time in the slave station will be described, and then in (b), the location of the failure point in the master station will be described.
[0037]
(A) Location of surge detection time at slave station
The procedure for locating the surge detection time in the central processing unit 141 of the slave station 1 is shown below.
The slave station receives the surge current generated at the time of failure by the ZCT 131, detects it by the filter circuit 132 and the surge signal detection circuit 133, and outputs the surge detection signal to the surge detection time holding circuit 134. Next, the surge detection time holding circuit 134 holds the reference time when the surge detection signal is received, and outputs it to the central processing unit 141 as the surge detection time. Subsequently, the central processing unit 141 automatically transmits the detection time data of the surge detection signal to the master station together with the slave station number as failure information.
[0038]
(B) Fault location at the master station
Below, the principle and procedure of the fault location in the central processing unit 23 of the master station 2 will be shown. First, in (i), the principle of fault location will be described, and then in (ii) the procedure will be described.
[0039]
(I) Principle of fault location
FIG. 4 shows the location principle diagram of the failure point.
When a ground fault occurs between the slave station (1) and the slave station (2), a traveling wave (surge) is generated as shown in FIG. When the traveling wave is detected at the slave station (1) and the slave station (2), assuming that the propagation velocity v of the traveling wave propagating through the transmission and distribution line is constant, each child from the failure occurrence point This is proportional to the distances L1 and L2 to the station.
[0040]
That is, the length L of the transmission / distribution line between the slave station (1) and the slave station (2) is known, and the time difference detected at the slave station (1) and the slave station (2) can be accurately detected. If it is possible, as shown in FIG. 4, the distance L1 from the slave station {circle around (1)} to the failure point can be obtained by the calculation formula “L1 = (L + (t1−t2) × v) / 2”.
[0041]
In the fault location system of the present embodiment, the length L of the transmission / distribution cable path between the slave stations (the power supply terminal and the terminal slave station) for examining the difference in surge time is calculated and stored in advance. is there. This length L is obtained by manual input or automatic measurement by GPS.
[0042]
For adjacent slave stations, based on the assumption that the transmission / distribution cable path is almost straight, the distance between the two transmission / distribution cable paths is determined based on the location information (latitude, longitude, altitude) of the slave station. Can be calculated.
Further, for the distance between the slave stations that are not adjacent to each other, the length L of the transmission / distribution cable path between the slave stations is obtained by adding the lengths of the transmission / distribution cable paths between the adjacent slave stations existing between them. be able to.
[0043]
(Ii) Fault location procedure
The central processing unit 23 of the master station 2 calculates and stores the length L of the transmission / distribution cable path between the slave station closest to the power supply terminal and the slave station at each end of the transmission / distribution cable network in advance.
Then, the central processing unit 23 selects a combination of the slave station 1 closest to the power supply end on the transmission and distribution line and the slave station 1 closest to the end of the main line and the branch line, and from the difference in the surge detection times of both slave stations. Locate the point of failure.
[0044]
That is, the central processing unit 23 detects the surge detection time t1 of the slave station on the power supply side, the surge detection time t2 of the slave station on the terminal side, the propagation velocity v of the surge, and the length of the transmission / distribution electric line between the slave stations. Based on the length L, the distance L1 on the transmission / distribution line from the slave station on the power source side to the position (failure point) where the failure occurred on the transmission / distribution line is expressed by the equation L1 = (L + (t1-t2) Xv) / 2.
However, v is 150 to 300 m / μs considering the case of an overhead line and the case of a cable distribution line. This v is more preferably 250 to 300 m / μs.
[0045]
If there are slave stations 1 and 1 that sandwich the failure point near the determined failure point, the failure point is determined again from the difference in the surge detection times of those slave stations, thereby determining the reliability of the orientation. Can raise the sex.
The failure point location procedure may be such that the operator gives a necessary instruction to the central processing unit 23 by manual operation each time to cause the failure point location processing, or the central processing unit 23 automatically performs the processing. You may set up a program to do it.
[0046]
In this case, an accurate time difference cannot be detected unless the time of the reference clocks of the slave stations at both ends is synchronized, but here, as described above, the standard time sent from the GPS satellite and each slave station The time of each slave station is synchronized by combining the time of the reference clock and correcting it as needed.
[0047]
(III) Display of failure location
When the central processing unit 23 of the master station 2 completes the location of the failure point, in order to notify the operator of the location of the failure, the transmission / distribution line diagram information stored in the auxiliary storage device 222 and the determined failure point are It is displayed on the screen of CRT241. Further, they are printed from the printer 242 in response to an operator request.
[0048]
(4) Operation of fault location system
The slave station 1 is attached to a power pole (steel tower) that supports the transmission and distribution line, and operates continuously for 24 hours so that it can be detected whenever a failure occurs.
The master station 2 may be installed, for example, at a branch or sales office of an electric power company and operated only while there is an operator, or 24 so that a failure point can be confirmed immediately when a failure occurs. It may be time driving.
[0049]
(5) Effect of fault location system
The failure point locating system according to the present embodiment combines the time measuring means 12 and the GPS receiving means 11 in the slave station to synchronize with each slave station and maintain an accurate time. The position of the failure point (distance from the slave station to the position of the failure point) is specified from the difference in the arrival times of the surge signals of the slave stations located at the terminal and the terminal. Moreover, even when a state in which GPS radio waves cannot be received occurs for a short period, the reference time inside the slave station can be used. Therefore, the failure point can be determined quickly and accurately.
[0050]
[Others]
In addition, in this invention, it can be set as the aspect variously changed within the range of this invention according to the objective and use, without being restricted to what is shown to the said Example. That is, the time error data, which is the difference between the reference time and the standard time obtained from the GPS, can be obtained for each day, and then the average value can be obtained. The average value can also be obtained by dividing by.
In addition, transmission of information from the slave station to the master station can be made using a wired or wireless public line network such as a mobile phone, a PHS, and a public telephone line, and is provided on a transmission and distribution line. A dedicated line network (metal cable, optical fiber, wireless, etc.) may be used. Further, a modulated signal may be conveyed on the transmission / distribution line.
[0051]
Further, the map data in the transmission / distribution line diagram information is not limited to the mode recorded in the auxiliary storage device, but a magnetic disk, an optical disk (CD-ROM, DVD, etc.), a magneto-optical disk (MO, etc.), etc. It may be recorded on other recording media. Also, map data may be downloaded from a server of a WWW site that operates a map information system on the Internet, or retrieved online. If data is downloaded from a server via the Internet or taken out online, the map information does not need to be maintained independently, and the latest map information can always be obtained.
[0052]
【The invention's effect】
In the reference time correction method according to claim 1 and the fault location system according to claim 2, the standard time obtained from GPS radio waves is accumulated for a certain period, and the reference time is corrected by the average value.
For this reason, the standard time synchronized between each slave station can be maintained, and the surge detection time at each slave station can be determined with the same accuracy. That is, there is little variation in surge detection time caused by the difference in surge rise time received by each slave station.
[0053]
In the failure point locating system according to claims 3 and 4, since the master station is provided, the master station can determine the failure point based on the information of the surge detection time from each slave station. Moreover, since the master station is provided separately from the slave stations provided in the transmission and distribution line network, it is possible to make the facilities of each slave station simple and compact by leaving the fault point location function to the master station equipment. it can.
In addition, even if the GPS receiver cannot receive GPS radio waves due to some kind of radio interference, etc., it will not interfere with the fault location function by using the reference time inside the slave station. It can be carried out.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a relationship between a master station and a slave station in a fault location system.
FIG. 2 is an explanatory diagram of each component of a slave station.
FIG. 3 is an explanatory diagram of each component of the master station.
FIG. 4 is an explanatory diagram showing the principle of identifying a fault location.
FIG. 5 is a schematic diagram for explaining a reference time correction method;
FIG. 6 is a schematic diagram for explaining a reference time correction method;
FIG. 7 is a schematic diagram for explaining a reference time correction method;
FIG. 8 is a graph for explaining a distribution of errors in standard time obtained by receiving GPS radio waves.
FIG. 9 is a graph for explaining an accumulated error of the oscillation circuit at the reference time.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1; Slave station, 11; GPS receiving means, 111; GPS antenna, 112; GPS receiver, 12; Timekeeping means, 121; Oscillator circuit, 122; Reference clock, 123; Reference time holding circuit, 124; , 13; surge detection means, 131; ZCT (zero phase current transformer), 132; filter circuit, 133; surge signal detection circuit, 134; surge detection time holding circuit, 14b; surge information transmission means, 141; 142; communication interface, 2; master station, 21; communication interface, 21a; slave station position information receiving means, 21b; slave station surge information receiving means, 22; map information storage means, 221; CD-ROM drive, 222; Auxiliary storage device 23; Central processing unit 23a; Transmission / distribution line diagram information creation means 23b; Fault section identification means 23c; Position specifying means, 24; TD line diagram information output means, 241; CRT, 242; printer, 25; keyboard (input means).

Claims (4)

In the correction method of the reference time used as the detection time of the surge voltage or surge current due to the failure that occurred in any part of the transmission and distribution line,
The difference between the GPS standard time obtained from the received GPS radio wave and the reference time when the standard time is obtained is obtained, and after accumulating the difference for a certain period, the average value of the accumulated differences is obtained. A method for correcting a reference time, wherein the reference time is corrected by adding to the reference time. A slave station (1) installed in the transmission / distribution line and transmitting information on the surge detection time to the master station (2), and the master station (2) for locating the failure point based on the information on the surge detection time; A fault location system having
The slave station (1) obtains a difference between the GPS standard time obtained from the received GPS radio wave and the reference time when the standard time is acquired, accumulates the difference for a certain period, and then accumulates the difference. The reference time is corrected by adding the average value of the differences to the reference time,
A failure point characterized in that a detection time of a surge voltage or surge current due to a failure occurring in any part of a transmission / distribution electric line is obtained from the corrected reference time and transmitted to the master station (2) through a communication network. Orientation system. The master station (2) includes the surge detection time t1 of one slave station of a pair of slave stations sandwiching the failure point of the transmission / distribution power line network, the surge detection time t2 of another slave station, and a surge The distance L1 on the transmission / distribution line from the one slave station to the failure point is expressed by the equation L1 = (L +) based on the propagation speed v of The failure point locating system according to claim 2, which is obtained from (t1-t2) × v) / 2. The master station (2) includes the surge detection time t1 of the slave station closest to the power supply end of the transmission / distribution power line network, the surge detection time t2 of the slave station at the end of the transmission / distribution power network, and the propagation speed of the surge Based on v and the length L of the transmission / distribution line between the slave stations, the distance L1 on the transmission / distribution line from the slave station on the power source side to the failure point is expressed by the equation L1 = (L + ( calculated from t1-t2) × v) / 2,
Furthermore, the surge detection time t3 of one slave station of the pair of slave stations sandwiching the failure point position obtained by the above calculation, the surge detection time t4 of the other slave stations, the surge propagation velocity v, Based on the length L ′ of the transmission / distribution cable path between the pair of slave stations, the distance L3 on the transmission / distribution cable path from the one slave station to the failure point is expressed by the equation L3 = (L ′ + The failure point locating system according to claim 2, which is obtained from (t3−t4) × v) / 2.

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