Information processing apparatus, information processing method, and program

Abstract

To accurately locate a ground point to find out a ground fault early.SOLUTION: An information processing apparatus executes: first processing of acquiring accident information including a current value of surge current when a distribution line is grounded, from a plurality of measurement terminals installed at a plurality of points of the distribution line; second processing of, on the basis of the accident information, determining if the surge current includes a pulse that, before changing in one direction along with the grounding of the distribution line, changes in a direction opposite to one direction; third processing of, when the surge current is determined to include the pulse in the second processing, obtaining a time obtained by approximating an initial first change point of the pulse, for every point as a surge arrival time at which the surge current arrives at the plurality of measurement terminals; and fourth processing of locating a ground point at which grounding occurs on the basis of a difference in the surge arrival time between the adjacent points.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an information processing device, an information processing method, and a program for accurately locating a ground fault point when a ground fault occurs on a power distribution line. [Background technology]

[0002] When a ground fault occurs in a distribution line (e.g., a 6 kV distribution system), a ground fault location system is known that locates the ground fault point in order to find out where in the distribution line the ground fault occurred (e.g., Patent Document 1). The earth fault point locating system includes, for example, a voltage sensor that detects a zero-phase voltage appearing on a power distribution line, a current sensor that detects a surge current flowing through the power distribution line, a measurement terminal, and an earth fault point locating device. The voltage sensor, the current sensor, and the measurement terminal are installed, for example, on each pole on which the power distribution line is erected, and the earth fault point locating device (for example, a computer) is installed, for example, at a power company or the like. Then, the multiple measurement terminals installed on each pole transmit information indicating a surge current that occurs when the balance of the zero-phase current is disturbed due to the occurrence of an earth fault current (leakage current) triggered by a change in the zero-phase voltage when a ground fault occurs, to the earth fault point locating device in association with information indicating the time obtained from a GPS satellite. Meanwhile, the earth fault point locating device locates an earth fault by performing a predetermined calculation based on the information indicating the surge current and the information indicating the time obtained from the multiple measurement terminals. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-63750 Summary of the Invention [Problem to be solved by the invention]

[0004] When a ground fault occurs, a surge current flows through the power distribution line. The ground fault point locating device, for example, performs linear or nonlinear approximation on the first change point of the surge current when a ground fault occurs to determine the surge arrival time when the surge current when a ground fault occurs reaches each measurement terminal, and locates the ground fault point based on this surge arrival time.

[0005] If the ground fault is, for example, a low-resistance ground fault, the amplitude of the surge current is large and the slope of the change in the surge current is steep. Therefore, the surge arrival time can be accurately determined by linearly or nonlinearly approximating the first change point of the surge current.

[0006] However, because the surge current contains multiple frequency components, the waveform of the surge current reaching each measurement terminal may be distorted depending on the phase velocity difference between the multiple frequency components, etc. In this case, the first change point of the surge current cannot be detected accurately, and there is a risk of a large error in locating the ground fault point.

[0007] The present invention has been made in consideration of the above-mentioned problems, and one object of the present invention is to provide an information processing device, an information processing method, and a program for accurately locating earth fault points and detecting earth fault accidents at an early stage. [Means for solving the problem]

[0008] One of the present inventions for achieving the above-mentioned object is an information processing device having a processor and a storage device, which executes a first process of acquiring accident information including a current value of a surge current when a ground fault occurs in the distribution line from a plurality of measurement terminals installed at a plurality of points on the distribution line, a second process of determining based on the accident information whether the surge current includes a pulse that changes in a direction opposite to the one direction before changing in one direction due to a ground fault in the distribution line, a third process of determining, if it is determined in the second process that the surge current includes the pulse, a time obtained by approximating the initial first change point of the pulse as the surge arrival time at which the surge current arrives at the plurality of measurement terminals for each of the points, and a fourth process of locating the ground fault point where the ground fault occurred based on the difference in the surge arrival time between the adjacent points.

[0009] In another aspect of the present invention for achieving the above object, in an information processing device, the second process includes, as a process for determining whether the pulse is included in the surge current, a first determination process for determining whether the peak value of the pulse is equal to or greater than a predetermined value, and a second determination process for determining whether the time width of the pulse when the current value of the surge current is a predetermined value is between a first time width and a second time width longer than the first time width, and it is determined that the pulse is included in the surge current when it is determined that the peak value of the pulse is equal to or greater than a predetermined value and that the time width of the pulse when the current value of the surge current is a predetermined value is between the first time width and the second time width.

[0010] Another aspect of the present invention for achieving the above object is that, in an information processing device, in the third process, it is deemed that the first change point occurs at a time that is a predetermined multiple of the time width between the first second change point when the surge current changes in one direction due to a ground fault in the power distribution line and the peak value of the pulse.

[0011] In another aspect of the present invention for achieving the above object, in an information processing device, in the third process, a time determined by linearly approximating the first change point is determined as the surge arrival time for each of the locations.

[0012] According to the information processing device of the present invention, in the case where the earth fault is, for example, a low resistance earth fault, even if the phase velocity difference between multiple frequency components causes distortion in the waveform of the surge current reaching each measurement terminal, it is possible to accurately locate the earth fault point and detect the earth fault early.

[0013] In addition, the problems and solutions disclosed in this application will be made clear by the description in the section of the preferred embodiment of the invention and the descriptions in the drawings. Effect of the Invention

[0014] According to the present invention, it is possible to accurately locate earth fault points and detect earth faults at an early stage. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a ground fault location system 100. [Figure 2A] FIG. 13 is a diagram showing an example of a change in surge current when a ground fault occurs due to a low resistance ground fault, as displayed on the display unit 155. [Figure 2B] 2B is a diagram showing a state in which a part of the change in surge current in FIG. 2A is enlarged and displayed on the display unit 155. FIG. [Figure 2C] 13 is a diagram showing a state in which a part of another change in surge current is enlarged and displayed on the display unit 155. FIG. [Figure 3A] This figure shows that when the ground fault is a low resistance ground fault, a pulse C that changes to the negative side occurs before the surge current changes sharply to the positive side, and a waveform G that changes gradually to the positive side occurs before pulse C. [Figure 3B] FIG. 3B is an enlarged view of a portion of FIG. 3A. [Figure 4]This is a flowchart showing the process in which, when a low resistance ground fault occurs, arrival time detection unit 153 detects the presence or absence of pulse C according to the algorithm of the "linear approximation method", and if pulse C is present, linearly approximates the first change point of pulse C. [Diagram 5] FIG. 1 is a diagram showing a method for locating a ground fault point. [Figure 6] 1 is a block diagram showing an example of hardware of an information processing device 300 that realizes the functions of the ground fault point locating device 150. FIG. [Figure 7] 4 is a flowchart showing an example of processing of the ground fault point locating device 150. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] At least the following matters will become clear from the description of this specification and the accompanying drawings. Hereinafter, the present invention will be described according to one embodiment with reference to the accompanying drawings. In this embodiment, the same or similar configurations may be given common reference symbols and their description may be omitted. In this embodiment, the letter "S" before the reference symbol indicates a processing step.

[0017] FIG. 1 is a block diagram showing a schematic configuration of a ground fault point locating system 100 according to this embodiment.

[0018] The ground fault point locating system 100 is a system that locates a ground fault point where a ground fault has occurred when a ground fault occurs in a distribution line 110 that is installed on multiple poles 160 installed between a substation (power source) and a consumer area (load). In this embodiment, the ground fault described below is assumed to be a low-resistance ground fault. The ground fault point locating system 100 includes, as means for locating a ground fault point, a plurality of voltage sensors 121, a plurality of current sensors 122, a plurality of measurement terminals 130, a plurality of battery terminals 140, and a ground fault point locating device 150 (information processing device).

[0019] The voltage sensor 121 is installed, for example, on each pole 160 on which the distribution line 110 is erected. For example, a potential transformer PD that detects a voltage appearing in each phase of the distribution line 110 can be adopted as the voltage sensor 121. When a ground fault occurs in the distribution line 110, the voltage sensor 121 detects a zero-phase voltage appearing in the distribution line 110 at the installation location of the pole 160.

[0020] The current sensor 122 is installed on each pole 160 in one-to-one correspondence with the voltage sensor 121 installed on the pole 160. For example, a zero-phase current transformer ZCT that combines currents flowing in all phases (R phase, S phase, T phase) of the distribution line 110 to detect a zero-phase current can be used as the current sensor 122. When a ground fault occurs at the installation location of the pole 160, the current sensor 122 detects a surge current flowing in the distribution line 110 due to a disturbance in the balance of the zero-phase currents in all phases caused by the occurrence of a ground fault current (leakage current). When a surge current occurs, all phases become unbalanced, generating a zero-phase voltage.

[0021] The sensor switch 120 is installed, for example, for each support pole 160. The sensor switch 120 accommodates the voltage sensor 121 and the current sensor 122 in a sealed state inside a housing to protect the voltage sensor 121 and the current sensor 122 from external factors such as wind, rain, and ultraviolet rays. In this embodiment, the voltage sensor 121 and the current sensor 122 are used not only in the earth fault point locating system 100 but also in a power distribution automation system. This power distribution automation system is a system that, when a fault section of the power distribution line 110 is detected, controls the opening and closing operation of the sensor switch 120 based on the detection results of the voltage sensor 121 and the current sensor 122, thereby isolating the fault section from a healthy section. The voltage sensor 121 and the current sensor 122 may be used only in the earth fault point locating system 100. The measurement terminal 130 is installed for each pole 160 so as to correspond one-to-one to the voltage sensor 121 and the current sensor 122 installed on the pole 160. The measurement terminal 130 includes a GPS receiver 131, a timer 132, and a memory 133. The measurement terminal 130 is connected to the voltage sensor 121 and the current sensor 122, and receives information indicating the zero-phase voltage detected by the voltage sensor 121 and the surge current detected by the current sensor 122. When a ground fault occurs in the distribution line 110, the zero-phase voltage changes and a surge current occurs. Therefore, in this embodiment, the measurement terminal 130 controls the storage operation of the memory 133 in response to a change in the zero-phase voltage when a ground fault occurs in the distribution line 110.

[0022] The battery terminal 140 is installed on each pole 160 so as to correspond one-to-one with the measurement terminal 130 installed on each pole 160. The battery terminal 140 is a power source for operating the measurement terminal 130 when the power supplied to the distribution line 110 is interrupted, and functions as a power source by, for example, storing the power supplied to the distribution line 110. The battery terminal 140 includes, for example, any of a lead battery, a lithium ion battery, a sodium sulfur battery, a nickel metal hydride battery, a redox flow battery, a fuel cell, a capacitor battery, and the like. As a result, the measurement terminal 130 operates on the power supplied to the distribution line 110, and operates on the power stored in the battery 134 when the power supplied to the distribution line 110 is interrupted.

[0023] The GPS satellites 170 are artificial satellites having an orbital altitude of, for example, several hundred to tens of thousands of km, and emit radio waves (microwaves) including orbital information and time information toward the Earth at regular intervals (for example, once per second). The GPS receiver 131 receives the time information included in the radio waves emitted from the GPS satellites 170. The timer 132 keeps accurate time in synchronization with the time information received by the GPS receiver 131. The memory 133 continues to store the current value of the surge current detected by the current sensor 122 in the memory area A at regular intervals (for example, 50 nsec) in association with the time kept by the timer 132, regardless of whether a ground fault has occurred in the power distribution line 110. When a ground fault occurs in the distribution line 110, the memory 133 reads out information associating time with the current value of the surge current in a period TA+TB including a period TA before the zero-phase voltage changes and a period TB after the zero-phase voltage changes from information associating time with the current value of the surge current (hereinafter referred to as "accident information") from the storage area A and stores it in the storage area B. Note that a data logger, for example, can be used as a device for writing and reading data to the memory 133. When a ground fault occurs in the distribution line 110, the measurement terminal 130 converts the accident information stored in the storage area B of the memory 133 into a text file in, for example, a CSV (Comma Separated Value) format, and then divides it into packets of a certain size and transmits it to the ground fault point locating device 150.

[0024] The earth fault point locating device 150 is a device such as a computer that locates an earth fault point in order to find out where on the distribution line 110 an earth fault has occurred when an earth fault occurs on the distribution line 110, and is installed, for example, at an electric power company.

[0025] The ground fault point locator 150 is connected to a plurality of measurement terminals 130 in a state in which two-way communication is possible via a communication network 180. The communication network 180 is, for example, a local area network (LAN), a wide area network (WAN), a dedicated line, a power line communication network, various public communication networks, etc.

[0026] The ground fault point locating device 150 includes an accident information receiving unit 151, a ground fault accident determining unit 152, an arrival time detecting unit 153, a ground fault point locating unit 154, a display unit 155, and a memory unit 156 as means for locating a ground fault point.

[0027] When a ground fault occurs in the power distribution line 110 , the accident information receiving unit 151 receives accident information from the multiple measurement terminals 130 via the communication network 180 .

[0028] The ground fault determination unit 152 determines whether the ground fault is a low resistance ground fault based on the current value of the surge current included in the fault information.

[0029] When comparing the magnitude of the surge current in the case of a low-resistance ground fault and a high-resistance ground fault, the magnitude of the surge current in the case of a low-resistance ground fault is greater than the magnitude of the surge current in the case of a high-resistance ground fault. Therefore, in the ground fault accident determination unit 152, a reference value is set in advance to compare the magnitude of the surge current in the case of a low-resistance ground fault and the magnitude of the surge current in the case of a high-resistance ground fault. For example, in the case where the direction of change of the surge current is positive, in order to determine whether this surge current is a low-resistance ground fault or a high-resistance ground fault, a reference value Iref that is lower than the maximum value of the surge current that changes in the case of a low-resistance ground fault and higher than the maximum value of the surge current that changes in the case of a high-resistance ground fault is set in the ground fault accident determination unit 152. In addition, when the direction of change of the surge current is negative, in order to determine whether this surge current is a low-resistance ground fault or a high-resistance ground fault, a reference value -Iref that is higher than the maximum value of the surge current that changes in the event of a low-resistance ground fault and lower than the maximum value of the surge current that changes in the event of a high-resistance ground fault is set in the ground fault accident determination unit 152.

[0030] The reference values ​​Iref, -Iref are values ​​determined by verifying the current values ​​of surge currents that flowed from the ground fault point to the measurement terminal 130 in various low resistance ground faults and high resistance ground faults that occurred in the past.

[0031] When the ground fault is a low-resistance ground fault, the peak values ​​of the surge current in the positive and negative directions are not within the display range of the display unit 155, and therefore cannot be confirmed on the display unit 155. On the other hand, when the ground fault is a high-resistance ground fault, the peak value of the surge current in the negative direction is at a level that falls within the display range of the display unit 155, and therefore can be confirmed on the display unit 155. Therefore, for example, the maximum current value that can be displayed on the display unit 155 is set to a reference value Iref, and the minimum current value that can be displayed on the display unit 155 is set to a reference value -Iref. As a result, when the peak values ​​of the surge current in the positive and negative directions exceed the reference values ​​Iref, -Iref and are not displayed within the display range of the display unit 155, the ground fault fault determination unit 152 determines that the ground fault is a low-resistance ground fault, and on the other hand, when the peak values ​​of the surge current in the positive and negative directions are displayed within the display range of the display unit 155, the ground fault fault is determined to be a high-resistance ground fault.

[0032] Furthermore, before a ground fault occurs, minute noise is superimposed on the surge current. In order to prevent this minute noise from being interpreted as a change in the surge current when a ground fault occurs, thresholds Ith and -Ith that the minute noise does not exceed are set in the ground fault fault determination unit 152. The values ​​of the thresholds Ith and -Ith are determined by verifying the current values ​​of the surge current that flowed from the ground fault point to the measurement terminal 130 in various low-resistance and high-resistance ground faults that occurred in the past.

[0033] When the surge current caused by the ground fault becomes larger than the threshold value Ith and then larger than the reference value Iref, the ground fault judgment unit 152 judges that the ground fault at this time is a low resistance ground fault in which the surge current changes in a positive direction. Also, when the surge current caused by the ground fault becomes smaller than the threshold value -Ith and then smaller than the reference value -Iref, the ground fault judgment unit 152 judges that the ground fault at this time is a low resistance ground fault in which the surge current changes in a negative direction.

[0034] When the ground fault judgment unit 152 judges that the ground fault is a low resistance ground fault, the arrival time detection unit 153 detects the surge arrival time, which is the time when the surge current when the ground fault occurs reaches each measurement terminal 130, using the "linear approximation method" described below.

[0035] 2A is a diagram showing an example of a surge current when the ground fault is a low-resistance ground fault, displayed on the display unit 155, and FIG. 2B and FIG. 2C are diagrams showing a part of another example of a surge current when the ground fault is a low-resistance ground fault, enlarged and displayed on the display unit 155, where the horizontal axis of each diagram indicates time (nsec) and the vertical axis indicates current (mA). The positive and negative change widths of the surge current that can be displayed on the display unit 155 are the same. When a ground fault occurs, the direction in which the current value of the surge current included in the accident information acquired from the measurement terminal 130 changes is either the positive or negative direction, depending on whether the surge current flows from the ground fault point toward the measurement terminal 130 on the substation side, or the surge current flows from the ground fault point toward the measurement terminal 130 on the opposite side of the substation. In Figs. 2A to 2C, when a ground fault occurs, the direction in which the current value of the surge current included in the fault information changes abruptly is the negative direction.

[0036] A low-resistance ground fault is a ground fault of a magnitude that causes a substation circuit breaker to operate, and is characterized by a large amplitude and a steep slope of the surge current, as described above. Therefore, when the "linear approximation method" is applied to the waveform of the surge current of a low-resistance ground fault, the variation in detecting the surge arrival time when the surge current arrives at the measurement terminal 130 is relatively small.

[0037] Therefore, when the ground fault is a low-resistance ground fault as shown in Fig. 2A, the arrival time detection unit 153 performs linear approximation by drawing a tangent to the change point of the waveform of the surge current which changes abruptly as shown in Fig. 2A, triggered by a change in the zero-phase voltage, for example, using an algorithm of the "linear approximation method," and determines the point where this tangent intersects with the time axis (a straight line parallel to the time axis at which the current value is 0 mA) as the surge arrival time. When the accident information stored in the memory 133 in the measurement terminal 130 is transmitted to the ground fault point locating device 150 and the current value of the surge current included in this accident information is displayed on the display unit 155, it is found that since the change in the surge current is abrupt, the variation in the position where the tangent drawn to the change point of the waveform of the surge current intersects with the time axis is small, and the change point of the surge current can be clearly captured, and therefore the location error of the ground fault point by the ground fault point locating unit 154 is small. In addition, the arrival time detection unit 153 linearly approximates the waveform of the surge current to detect the surge arrival time when the ground fault is a low-resistance ground fault. In addition to linear approximation, nonlinear approximation such as exponential approximation, logarithmic approximation, and power approximation may be appropriately adopted to reduce detection errors in the surge arrival time.

[0038] Figures 2B and 2C show examples of surge current when the ground fault is a low-resistance ground fault and the arrival time detection unit 153 determines the surge arrival time by approximating the first change point of the surge current waveform that drops sharply according to the "linear approximation method" algorithm, but the ground fault point location unit 154 is unable to accurately locate the ground fault point at this surge arrival time.

[0039] In Fig. 2B, it can be seen that a pulse C less than the threshold value Ith is generated on the positive side before the surge current becomes lower than the threshold value -Ith and falls sharply in the negative direction. Also, in Fig. 2C, it can be seen that a pulse C less than the threshold value Ith is generated on the positive side before the surge current becomes lower than the threshold value -Ith and falls sharply in the negative direction, and furthermore, before this pulse C is generated, a waveform G with a gradual change slightly lower than the threshold value -Ith is generated on the negative side. When the applicant performed verification on the waveform of the surge current in Fig. 2B, it was found that the accuracy of locating the earth fault point located by the earth fault point locating unit 154 is improved by using the surge arrival time obtained by approximating the first change point of the pulse C using the algorithm of the "linear approximation method". In addition, when the applicant performed verification on the surge current waveform in Fig. 2C, it was found that the accuracy of locating the earth fault point located by the earth fault point locator 154 was improved by using the surge arrival time obtained by approximating the first change point of pulse C without approximating the first change point of waveform G using the algorithm of the "linear approximation method". In other words, it was found that identifying the first change point of pulse C and approximating the first change point of pulse C according to the algorithm of the "linear approximation method" is a process necessary for improving the accuracy of locating the earth fault point.

[0040] The process in which arrival time detection section 153 linearly approximates the first change point of pulse C according to the algorithm of the "linear approximation method" will be described below.

[0041] Fig. 3A is a diagram showing how, when a ground fault is a low-resistance ground fault, a pulse C that changes to the negative side occurs before the surge current changes sharply to the positive side, and a waveform G that changes gradually to the positive side occurs before the pulse C, and Fig. 3B is a diagram showing an enlarged portion of Fig. 3A, in which the horizontal axis of each diagram indicates the difference in time from the origin (nsec), and the vertical axis indicates the difference in current from the origin (mA). Fig. 4 is a flowchart showing the process in which, when a low-resistance ground fault occurs, arrival time detection unit 153 detects the presence or absence of pulse C according to the algorithm of the "linear approximation method", and if pulse C is present, linearly approximates the first change point of pulse C.

[0042] First, when a low-resistance earth fault occurs and a change in the zero-phase voltage causes the surge current to exceed the threshold Ith and then to exceed the reference value Iref, causing a steep positive change, the arrival time detection unit 153 detects the first change point of the surge current, which is to be tangent to the "linear approximation method", from the waveform of the surge current included in the accident information (S1010). Then, since the surge current has changed in the positive direction, the arrival time detection unit 153 detects whether or not there is a pulse C that changes to the negative side before the surge current changes in the positive direction in the subsequent steps.

[0043] The arrival time detection unit 153 sets the first change point of the surge current detected in step S1010 as the origin shown in Figures 3A and 3B (S1020). Specifically, in Figures 3A and 3B, if the detection time (horizontal axis) of the change point is t' and the current value (vertical axis) of the change point is i', the arrival time detection unit 153 sets the coordinate position of (t', i') as the origin. If the detection time other than the origin is t and the current value is i, the arrival time detection unit 153 converts the coordinate position (t, i) other than the origin to the difference (Δt, Δi) from the coordinate position (t', i') of the origin, and detects the pulse C that changes to the negative side.

[0044] In Figures 3A and 3B, in order to detect the negative side pulse C, an exploration threshold 1 (e.g., -50 mA), which has an absolute value smaller than the absolute value of threshold -Ith and larger than the absolute value of the negative component of the noise, is set at a coordinate position lower than the origin, and an exploration threshold 2 (e.g., 30 mA), which has an absolute value smaller than the absolute value of exploration threshold 1 and larger than the absolute value of the positive component of the noise, is set at a coordinate position higher than the origin.

[0045] In addition, in Figures 3A and 3B, in order to detect negative side pulse C, an inspection time 1, which is a time going back from the origin, and an inspection time 2, which is also a time going back from the origin but is longer than inspection time 1, are set at coordinate positions that are time periods before the origin.

[0046] In other words, when the waveform contained in the accident information is traced back from the origin to the previous time period, if the waveform changes in the negative direction and crosses the search threshold 1 within the search time 2, the arrival time detection unit 153 will determine that this change in the waveform to the negative side is a sufficiently large change that it can be distinguished from noise (determination process A).

[0047] Furthermore, if the waveform begins to change in a positive direction and crosses search threshold 2 within search time 2, the arrival time detection unit 153 will determine that the shape of this waveform that has changed to the negative side is a pulse shape (determination process B).

[0048] Furthermore, if the waveform starts to change in a positive direction and intersects with search threshold 2 at the time between search time 1 and search time 2, the arrival time detection unit 153 will determine that this waveform has a sufficient time width to be a pulse (determination process C).

[0049] In arrival time detection section 153, the pulse that is determined to be positive in the above determination processes A to C is pulse C that changes to the negative side.

[0050] Search threshold 1, search threshold 2, search time 1, and search time 2 are fixed values ​​that are appropriately set with reference to data obtained from experiments, etc., as values ​​that can detect a pulse C that changes to the negative side. When detecting a pulse C that changes to the positive side, search threshold 1 is set for the positive current value and search threshold 2 is set for the negative current value, which is the opposite of when detecting a pulse C that changes to the negative side.

[0051] The arrival time detection unit 153 acquires waveform information from the accident information, and performs a first determination process to determine whether the waveform crosses the search threshold 1 within the search time 2 as it changes in the negative direction while going back in time from the origin (S1030).

[0052] If the waveform crosses search threshold 1 within search time 2 while changing in the negative direction (S1030: YES), arrival time detection unit 153 determines that the change in the negative direction of the waveform is sufficiently large to be distinguished from noise.

[0053] Next, the arrival time detection unit 153 performs a second determination process to determine whether the waveform changes from the negative direction to the positive direction and intersects with the search threshold 2 within the search time 2 (S1040).

[0054] If the waveform changes from the negative direction to the positive direction and crosses search threshold 2 within search time 2 (S1040: YES), arrival time detection unit 153 determines that the shape of this waveform that has changed to the negative side is a pulse shape.

[0055] Next, the arrival time detection unit 153 performs a third determination process to determine whether the waveform changes from the negative direction to the positive direction and intersects with the search threshold 2 at the time between the search time 1 and the search time 2 (S1050).

[0056] If the waveform changes from the negative direction to the positive direction and intersects with search threshold 2 at the time between search time 1 and search time 2 (S1050: YES), the arrival time detection unit 153 determines that this waveform is a pulse having a sufficient time width and is pulse C changing to the negative side.

[0057] Next, since the presence of pulse C having a negative peak value between the time when pulse C crossed the first threshold 1 and the time when pulse C crossed the second threshold was detected, the arrival time detection unit 153 detects the coordinate position (tp, ip) when pulse C changed from a negative change to a positive change as the coordinate position of the negative peak value of pulse C (S1060).

[0058] Next, the arrival time detection unit 153 uses the detection result of the coordinate position (tp, ip) to calculate the time width Δt=α1=tp-t′ when tracing back from the origin to the peak value (S1070).

[0059] Next, the arrival time detection unit 153 multiplies the time width α1 by a correction coefficient larger than 1 prepared in advance to obtain a time width α2 larger than the time width α1, and sets the first change point of the pulse C to a time that is the time width α2 back from the origin (S1080). In other words, the change point to which the tangent is drawn by the "tangent approximation method" is corrected from the change point of the origin to the first change point of the pulse C. Here, the correction coefficient is, for example, a fixed value obtained from the relationship between the origin and the negative peak value of the pulse C in various past low resistance ground faults.

[0060] The arrival time detection unit 153 detects the surge arrival time by drawing a tangent to the change point of the pulse C found in step S1080 according to the algorithm of the "tangent approximation method" (S1090).

[0061] Furthermore, if the waveform changes in the negative direction but does not intersect with search threshold 1 within search time 2 (S1030: NO), or if the waveform changes from the negative direction to the positive direction and does not intersect with search threshold 2 within search time 2 (S1040: NO), or if the waveform changes from the negative direction to the positive direction and does not intersect with search threshold 2 in the time between search time 1 and search time 2 (S1050: NO), then pulse C has not been detected, and the arrival time detection unit 153 detects the surge arrival time by drawing a tangent to the first change point of the surge current obtained in step S1010 according to the algorithm of the "tangent approximation method" (S1100).

[0062] In this manner, the arrival time detection unit 153 determines the surge arrival time when the ground fault is a low resistance ground fault so as to reduce the location error of the ground fault point.

[0063] FIG. 5 is a diagram showing a method for locating an earth fault point. The surge arrival time indicated in this method is the surge arrival time detected by arrival time detection unit 153 when the earth fault is a low resistance earth fault.

[0064] The earth fault point locating unit 154 locates the earth fault point using a total of three terminals: one measurement terminal 130A on the substation side of the earth fault point and two measurement terminals 130B, 130C on the customer area side of the earth fault point, or two measurement terminals 130A, 130B on the substation side of the earth fault point and one measurement terminal 130C on the customer area side of the earth fault point.

[0065] For convenience of explanation, the position where the ground fault occurs in the distribution line 110 is a predetermined position between the measurement terminal 130A, which is on the substation side of the ground fault point, and the measurement terminal 130B, which is on the customer area side of the ground fault point. In other words, among the combinations of two measurement terminals 130 sandwiching the ground fault point, the surge arrival time in the combination of two adjacent measurement terminals 130A and 130B is earlier than the surge arrival time in other combinations of two measurement terminals 130. Alternatively, the ground fault point locating device 150 can also identify between which measurement terminals 130 the ground fault occurred depending on whether the surge current acquired from the three measurement terminals 130A, 130B, and 130C is positive or negative. Here, the distance between the ground fault point and the measurement terminal 130A is defined as X. Also, the distance between the measurement terminals 130A and 130B is defined as Lab, and the distance between the measurement terminals 130A and 130C is defined as Lac. Moreover, since the surge current flows radially on the distribution line 110 toward the measurement terminals 130A, 130B, and 130C, the propagation speed of the surge current at this time (hereinafter referred to as "surge propagation speed") is U. Moreover, the surge arrival times at which the surge current reaches the measurement terminals 130A, 130B, and 130C from the ground fault point are respectively designated as ta, tb, and tc. Note that, for the surge propagation speed U, the surge propagation speed described in, for example, Japanese Patent No. 4039576 can be used, and therefore the explanation thereof will be omitted.

[0066] Using the distance Lab between the measurement terminals 130A and 130B and the surge arrival times ta and tb at which the surge current reaches the measurement terminals 130A and 130B, the distance X between the ground fault point and the measurement terminal 130A is given by: X=(Lab / 2)+(ta-tb)U / 2 ···(1) As shown in the figure.

[0067] In addition, using the distance Lac between the measurement terminals 130A and 130C and the surge arrival times ta and tc at which the surge current reaches the measurement terminals 130A and 130C, the distance X between the ground fault point and the measurement terminal 130A is given by: X=(Lac / 2)+(ta-tc)U / 2 ···(2) As shown in the figure.

[0068] By solving the simultaneous equations (1) and (2), the distance X between the ground fault point and the measurement terminal 130A is calculated.

[0069] The earth fault point locating unit 154 employs the surge arrival time detected by the arrival time detecting unit 153, which allows the location error to be small, and therefore it becomes possible to locate an earth fault point with a small location error. For example, a location error of about ± several km on the substation side and on the consumer area side based on the earth fault point can be narrowed to about ± several hundred meters, making it possible to significantly reduce the burden on workers in terms of patrol work until they find the earth fault position.

[0070] Display unit 155 displays, for example, a combination of the waveform of the surge current during period TA+TB when the ground fault shown in FIG. 2A is a low resistance ground fault and the waveform of an enlarged portion of the surge current in FIG. 2A shown in FIG. 2B, or the waveform before the surge current changes sharply shown in FIG. 3A and FIG. 3B.

[0071] The memory unit 156 stores information such as a control program for the earth fault point locating device 150 to locate the earth fault point, accident information received by the accident information receiving unit 151, the type of earth fault accident determined by the earth fault accident determination unit 152 (low resistance earth fault, high resistance earth fault), the surge arrival time detected by the arrival time detection unit 153, and the earth fault point located by the earth fault point locating unit 154.

[0072] FIG. 6 is a block diagram showing an example of hardware of an information processing device 300 that realizes the functions of the ground fault point locating device 150 shown in FIG.

[0073] The information processing device 300 includes a processor 310, a main memory device 320, an auxiliary memory device 330, an input device 340, an output device 350, and a communication device 360. The information processing device 300 is, for example, a personal computer, an office computer, various server devices, a general-purpose machine, etc. All or a part of the information processing device 300 may be realized using virtual information processing resources provided using virtualization technology, such as a virtual server provided by a cloud system.

[0074] The processor 310 is configured using, for example, a Central Processing Unit (CPU), a Micro Processing Unit (MPU), a Graphics Processing Unit (GPU), a Field Programmable Gate Array (FPGA), an Application Specific Integrated Circuit (ASIC), an Artificial Intelligence (AI) chip, etc.

[0075] The main memory device 320 is a device that stores programs and data, and is, for example, a Read Only Memory (ROM), a Random Access Memory (RAM), or a non-volatile memory (NVRAM (Non Volatile RAM)).

[0076] The auxiliary storage device 330 is, for example, a solid state drive (SSD), a hard disk drive, an optical storage device (such as a compact disc (CD) or a digital versatile disc (DVD)), a storage system, an IC card, an SD card, a read / write device for a recording medium such as an optical recording medium, a storage area of ​​a cloud server, etc. Programs and data can be read into the auxiliary storage device 330 via a recording medium reader or a communication device 360. The programs and data stored in the auxiliary storage device 330 are read into the main storage device 320 as needed.

[0077] The input device 340 is an interface that accepts input from the outside, and is, for example, a keyboard, a mouse, a touch panel, a card reader, a pen-input tablet, a voice input device, or the like.

[0078] The output device 350 is an interface that outputs various information such as the progress of processing and the results of processing. The output device 350 is, for example, a display device (LCD (Liquid Crystal Display), graphic card, etc.) that visualizes the various information described above, a device that converts the various information described above into voice (voice output device (speaker, etc.)), or a device that converts the various information described above into text (printer, etc.). The information processing device 300 may be configured to input and output information to and from other devices via the communication device 360.

[0079] The input device 340 and the output device 350 constitute a user interface that receives information from the user and presents information to the user.

[0080] The communication device 360 ​​is a device that realizes communication (wired communication or wireless communication) with other devices via a communication infrastructure such as the communication network 180, and is configured using, for example, a NIC (Network Interface Card), a wireless communication module, a USB module, etc.

[0081] The information processing device 300 may include, for example, an operating system, a file system, a data base management system (DBMS) (relational database, NoSQL, etc.), a key-value store (KVS), etc.

[0082] The functions of the earth fault point locating device 150 are realized by the processor 310 of the information processing device 300 reading and executing a control program stored in the main memory device 320, or by the functions of the hardware (FPGA, ASIC, AI chip, etc.) constituting the information processing device 300. In this embodiment, the functions of the memory unit 156 of the earth fault point locating device 150 are realized by the main memory device 320 and the auxiliary memory device 330 of the information processing device 300, and the functions of the accident information receiving unit 151, the earth fault accident determination unit 152, the arrival time detection unit 153, and the earth fault point locating unit 154 of the earth fault point locating device 150 are realized by the processor 310 of the information processing device 300 operating in accordance with the control program. Furthermore, the accident information receiving unit 151 of the earth fault point locating device 150 is realized by the processor 310 of the information processing device 300 controlling the input device 340 and the communication device 360, and the display unit 155 of the earth fault point locating device 150 is realized by the processor 310 of the information processing device 300 controlling the output device 350.

[0083] 7 is a flowchart showing an example of the process of the ground fault point locating device 150. It is assumed that the ground fault occurs between the measurement terminals 130A and 130B in FIG.

[0084] First, in the ground fault point locating device 150, the accident information receiving unit 151 determines whether or not it has received accident information generated in association with a ground fault from each measurement terminal 130 (S2010). If the accident information receiving unit 151 has not received any accident information (S2010: NO), the operation of this step S2010 is repeatedly executed.

[0085] Next, when the accident information receiving unit 151 receives the accident information (S2010: YES), the ground fault accident determination unit 152 determines whether the ground fault is a low resistance ground fault from the current value of the surge current included in each accident information (S2020). For example, when the current value of the surge current is greater than the reference value Iref or the current value of the surge current changes to be smaller than the reference value -Iref and the peak value of the surge current cannot be confirmed on the display unit 155, the ground fault accident determination unit 152 determines that the ground fault at this time is a low resistance ground fault (S2020: YES). On the other hand, when the peak value of the surge current can be confirmed on the display unit 155 and the ground fault accident determination unit 152 does not determine that the ground fault at this time is a low resistance ground fault (S2020: NO), the process is terminated.

[0086] Next, if the ground fault judgment unit 152 judges that the ground fault is a low resistance ground fault (S2020: YES), the arrival time detection unit 153 detects the surge arrival time by linearly approximating the first change point of pulse C when pulse C is present, and on the other hand, if pulse C is not present, detects the surge arrival time by linearly approximating the first change point of the surge current (S2030), according to the flowchart shown in FIG.

[0087] Next, the ground fault point locating unit 154 performs a process of locating the ground fault point from the equations (1) and (2) based on the difference between the surge arrival times ta and tb obtained in step S2030 (S2040).

[0088] Next, the display unit 155 displays the result of locating the ground fault point (S2050).

[0089] As described above, the information processing device 300 having the processor 310 and memory devices (main memory device 320 and auxiliary memory device 330) executes a first process of acquiring accident information including the current value of the surge current when the distribution line 110 has a ground fault from multiple measurement terminals 130 installed at multiple points on the distribution line 110, a second process of determining whether the surge current includes a pulse C that changes in the opposite direction to the one direction before changing in one direction due to the ground fault on the distribution line 110 based on the accident information, a third process of determining, if it is determined in the second process that the surge current includes pulse C, an approximation of the first change point (first change point) of pulse C for each point as the surge arrival time when the surge current reaches the multiple measurement terminals 130, and a fourth process of locating the ground fault point where the ground fault occurred based on the difference in surge arrival time between adjacent points.

[0090] In addition, in the information processing device 300, the second process includes, as a process for determining whether or not pulse C is included in the surge current, a first determination process for determining whether the peak value of pulse C is equal to or greater than search threshold 1, and a second determination process for determining whether or not the time width of pulse C when the current value of the surge current is a predetermined value is a length between search time 1 and search time 2.When it is determined that the peak value of pulse C is equal to or greater than search threshold 1 and that the time width of pulse C when the current value of the surge current is a predetermined value is a length between search time 1 and search time 2, it is determined that pulse C is included in the surge current.

[0091] In addition, in the information processing device 300, in the third process, the first change point is regarded as occurring at a time that is a time width obtained by multiplying the time width between the first second change point when the surge current changes in one direction due to a ground fault in the power distribution line 110 and the peak value of pulse C by a correction coefficient greater than 1.

[0092] In the third process, the information processing device 300 determines, for each point, the time determined by linearly approximating the first change point as the surge arrival time.

[0093] According to the information processing device 300, when the ground fault is, for example, a low resistance ground fault, even if the phase velocity difference between multiple frequency components causes distortion in the waveform of the surge current reaching each measurement terminal 130, it is possible to accurately locate the ground fault point and detect the ground fault early.

[0094] It should be noted that the present embodiment is provided for the purpose of facilitating understanding of the present invention, and is not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and equivalents thereof are also included in the present invention. [Explanation of symbols]

[0095] 100 Earth fault location system 110 Power Distribution Line 120 Sensor switch 121 Voltage Sensor 122 Current Sensor 130 Measurement terminal 131 GPS receiver 132 Timer 133 Memory 140 Battery Terminal 150 Earth fault location device 151 Accident Information Receiving Department 152 Earth fault fault judgment unit 153 Arrival time detection unit 154 Earth fault point locator 155 Display section 160 Post 170 GPS satellites 180 Communication Network 300 Information processing device 310 Processor 320 Main storage 330 Auxiliary storage device 340 Input Device 350 Output Device 360 Communication Devices

Claims

1. A processor and a storage device are included. A first process of acquiring accident information including a current value of a surge current when a ground fault occurs in the distribution line from a plurality of measurement terminals installed at a plurality of points on the distribution line; a second process for determining whether or not the surge current includes a pulse that changes in a direction opposite to the one direction before the surge current changes in a direction associated with a ground fault in the power distribution line based on the accident information; a third process for calculating, for each of the points, a time obtained by approximating a first change point of the pulse when it is determined in the second process that the surge current includes the pulse, as a surge arrival time when the surge current reaches the plurality of measurement terminals; A fourth process of locating a ground fault point where a ground fault has occurred based on a difference in the surge arrival time between the adjacent points; An information processing device that executes the above.

2. 2. The information processing device according to claim 1, The second process includes: The process of determining whether the pulse is included in the surge current includes: a first determination process for determining whether a peak value of the pulse is equal to or greater than a predetermined value; a second determination process for determining whether a time width of the pulse when the current value of the surge current is a predetermined value is between a first time width and a second time width longer than the first time width; Including, When it is determined that the peak value of the pulse is equal to or greater than a predetermined value, and when it is determined that the time width of the pulse when the current value of the surge current is the predetermined value is between the first time width and the second time width, it is determined that the pulse is included in the surge current. Information processing device.

3. 3. The information processing device according to claim 2, In the third process, The first change point is deemed to occur at a time that is a predetermined multiple of the time between the first second change point when the surge current changes in one direction due to a ground fault in the distribution line and the peak value of the pulse, from the second change point. Information processing device.

4. 4. The information processing device according to claim 3, In the third process, The time obtained by linearly approximating the first change point is obtained as the surge arrival time for each of the points. Information processing device.

5. An information processing method of an information processing device having a processor and a storage device, A first step of acquiring accident information including a current value of a surge current when a ground fault occurs in a distribution line from a plurality of measurement terminals installed at a plurality of points on the distribution line; a second step of determining whether the surge current includes a pulse that changes in a direction opposite to the one direction before the surge current changes in a direction associated with a ground fault in the power distribution line based on the accident information; a third step of approximating a time of a first change point of the pulse when it is determined in the second step that the surge current includes the pulse, as a surge arrival time at which the surge current reaches the plurality of measurement terminals for each of the points; A fourth step of locating a ground fault point where a ground fault has occurred based on a difference in the surge arrival time between adjacent points; An information processing method comprising:

6. 6. The information processing method according to claim 5, The second step comprises: As a step of determining whether the pulse is included in the surge current, a first determination step of determining whether a peak value of the pulse is equal to or greater than a predetermined value; a second determination step of determining whether a time width of the pulse when the current value of the surge current is a predetermined value is between a first time width and a second time width longer than the first time width; Including, When it is determined that the peak value of the pulse is equal to or greater than a predetermined value, and when it is determined that the time width of the pulse when the current value of the surge current is the predetermined value is between the first time width and the second time width, it is determined that the pulse is included in the surge current. Information processing methods.

7. 7. An information processing method according to claim 6, In the third step, The first change point is deemed to occur at a time that is a predetermined multiple of the time between the first second change point when the surge current changes in one direction due to a ground fault in the distribution line and the peak value of the pulse, from the second change point. Information processing methods.

8. 8. An information processing method according to claim 7, In the third step, The time obtained by linearly approximating the first change point is obtained as the surge arrival time for each of the points. Information processing methods.

9. A computer having a processor and a storage device, A first process of acquiring accident information including a current value of a surge current when a ground fault occurs in the distribution line from a plurality of measurement terminals installed at a plurality of points on the distribution line; a second process for determining whether or not the surge current includes a pulse that changes in a direction opposite to the one direction before the surge current changes in a direction associated with a ground fault in the power distribution line based on the accident information; a third process for calculating, for each of the points, a time obtained by approximating a first change point of the pulse when it is determined in the second process that the surge current includes the pulse, as a surge arrival time when the surge current reaches the plurality of measurement terminals; A fourth process of locating a ground fault point where a ground fault has occurred based on a difference in the surge arrival time between the adjacent points; A program that executes the following.

10. The program according to claim 9, The second process includes: The process of determining whether the pulse is included in the surge current includes: a first determination process for determining whether a peak value of the pulse is equal to or greater than a predetermined value; a second determination process for determining whether a time width of the pulse when the current value of the surge current is a predetermined value is between a first time width and a second time width longer than the first time width; Including, When it is determined that the peak value of the pulse is equal to or greater than a predetermined value, and when it is determined that the time width of the pulse when the current value of the surge current is the predetermined value is between the first time width and the second time width, it is determined that the pulse is included in the surge current. program.

11. The program according to claim 10, In the third process, The first change point is deemed to occur at a time that is a predetermined multiple of the time between the first second change point when the surge current changes in one direction due to a ground fault in the distribution line and the peak value of the pulse, from the second change point. program.

12. The program according to claim 11, In the third process, The time obtained by linearly approximating the first change point is obtained as the surge arrival time for each of the points. program.

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