Information processing device, information processing method, program, and ground fault location system

Abstract

To accurately pinpoint the fault location and detect ground fault accidents early. [Solution] An information processing device having a processor and a memory device acquires fault information from a plurality of measurement terminals installed at multiple points on a power distribution line, including a first current value which is the current value of the surge current when the power distribution line has a ground fault, and a second current value obtained based on the first current value and having an amplitude smaller than the amplitude of the first current value. When the amplitude of the first current value is greater than or equal to a predetermined threshold, the time when the second current value first reaches its peak value is determined for each of the multiple measurement terminals as the surge arrival time when the surge current reaches the plurality of measurement terminals, and the ground fault point where the ground fault occurred is determined based on the difference in the surge arrival times between adjacent points.

Description

Technical Field

[0001] The present invention relates to an information processing apparatus, an information processing method, a program, and a ground fault point calibration system for improving the calibration accuracy of ground fault points.

Background Art

[0002] When a ground fault occurs in a distribution line (for example, a 6 kV distribution system), a ground fault point calibration system for calibrating the ground fault point to find out where the ground fault has occurred in the distribution line is known (for example, Patent Document 1). The ground fault point calibration system is composed of, for example, a voltage sensor that detects the zero-phase voltage appearing in the distribution line, a current sensor that detects the surge current flowing in the distribution line, a measurement terminal, and a ground fault point calibration device. The voltage sensor, the current sensor, and the measurement terminal are installed, for example, for each pole on which the distribution line is erected, and the ground fault point calibration device (for example, a computer) is installed, for example, in an electric power company or the like. Then, when a ground fault occurs, for example, a plurality of measurement terminals installed for each pole associate the information indicating the surge current generated due to the disturbance of the zero-phase current balance with the information indicating the time obtained from the GPS satellite, and transmit it to the ground fault point calibration device. On the other hand, the ground fault point calibration device calibrates the ground fault point by performing a predetermined calculation based on the information indicating the surge current and the information indicating the time obtained from a plurality of measurement terminals.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a ground fault occurs, a surge current flows through the power distribution line. A ground fault location device approximates the rising edge of the surge current when a ground fault occurs with a straight line, a curve, etc., to determine the surge arrival time when the surge current reaches each measurement terminal, and then determines the ground fault location based on this surge arrival time.

[0005] Here, surge current contains multiple frequency components, and each frequency component propagates through the power distribution line according to its respective phase velocity. Therefore, distortion occurs in the surge current due to the difference in phase velocities of each frequency component. Consequently, methods that approximate the rise of the surge current with straight lines, curves, etc., will result in large variations in the surge arrival time due to the effect of the phase velocity difference of each frequency component, and thus large errors in locating the ground fault point. This may also lead to a significant delay in detecting the ground fault location.

[0006] This invention was made in view of the above-mentioned problems, and one of its objectives is to accurately locate the ground fault point and to detect ground fault accidents at an early stage. [Means for solving the problem]

[0007] One of the present inventions for achieving the above objective is an information processing device having a processor and a memory device, which acquires fault information from a plurality of measurement terminals installed at multiple points on a power distribution line, including a first current value which is the current value of the surge current when the power distribution line has a ground fault, and a second current value obtained based on the first current value and having an amplitude smaller than the amplitude of the first current value, and when the amplitude of the first current value is greater than or equal to a predetermined threshold, the time when the second current value first reaches its peak value is determined for each of the multiple measurement terminals as the surge arrival time when the surge current reaches the plurality of measurement terminals, and the ground fault point where the ground fault occurred is determined based on the difference in the surge arrival times between adjacent points.

[0008] Surge currents contain multiple frequency components, which include a central frequency component A and multiple frequency components B that differ from the central frequency component A, similar to a normal distribution. The central frequency component A is the frequency component corresponding to the peak value of the surge current envelope, and propagates through the power line at a constant speed regardless of the phase velocity difference when the multiple frequency components B other than the central frequency component A propagate through the power line. Therefore, as a method for accurately determining the surge arrival time, it is preferable to use the first peak value of the surge current as the surge arrival time, rather than approximating the rise of the surge current with a straight line, curve, etc., to determine the surge arrival time.

[0009] There are different types of ground faults, such as low-resistance ground faults and high-resistance ground faults. A low-resistance ground fault is a relatively large-scale ground fault that can trip the circuit breakers of a substation. The amplitude of the surge current when a low-resistance ground fault occurs is significantly larger than the amplitude of the surge current when a high-resistance ground fault occurs. Therefore, if an information processing device only acquires the first current value, which is the current value of the surge current, when a low-resistance ground fault occurs, depending on the specifications of the information processing device, it may not be able to recognize the first peak value of the surge current, and thus may not be able to locate the ground fault point.

[0010] According to the information processing device of the present invention, in addition to the first current value, a second current value with an amplitude smaller than that of the first current value is also acquired as the current value of the surge current. Therefore, even in the case of a low-resistance ground fault, for example, by setting the time when the second current value first reaches its peak value as the surge arrival time, the ground fault point can be accurately determined and the ground fault can be detected early.

[0011] Another aspect of the present invention for achieving the above objective is an information processing device, wherein the first current value is the value of the surge current input to the primary side of a plurality of current transformers installed at a plurality of locations, and the second current value is the value of the surge current output from the secondary side of the plurality of current transformers.

[0012] According to the information processing device of the present invention, since the first current value and the second current value output from the current transformer are acquired simultaneously, it is possible to display the first current value and the second current value side by side on the display unit.

[0013] Another aspect of the present invention for achieving the above objective is an information processing device, wherein the first current value is the value of the surge current when the power distribution line experiences a low-resistance ground fault. The first current value has an amplitude in which the peak value of the first current value exceeds the display range of the display unit, and the second current value has an amplitude in which the peak value of the second current value is displayed within the display range of the display unit.

[0014] According to the information processing device of the present invention, it is possible to simultaneously check the first current value and the second current value on the display unit when a low-resistance ground fault occurs.

[0015] Furthermore, the problems disclosed in this application and their solutions will be made clear from the description in the section on embodiments for carrying out the invention and from the drawings. [Effects of the Invention]

[0016] According to the present invention, it is possible to accurately locate the ground fault point and detect ground fault accidents at an early stage. [Brief explanation of the drawing]

[0017] [Figure 1] This is a block diagram showing the schematic configuration of the ground fault location system 100. [Figure 2A] This figure shows an example of the change in the first current value, which remains as detected by the zero-phase current transformer 122, as displayed on the display unit 155 when the ground fault is a low-resistance ground fault. [Figure 2B] This figure shows an example of a change in the second current value, which has a smaller amplitude than the first current value, appearing on the secondary side of the current transformer 123 when the ground fault is a low-resistance ground fault, as displayed on the display unit 155. [Figure 2C]It is a diagram showing a state where waveforms of the second current value in FIG. 2B and the first current value in FIG. 2A are displayed in the upper and lower parts of the display unit 155, respectively. [Figure 3A] It is a diagram showing a state where an example of a change in the first current value remaining detected by the zero-phase current transformer 122 when the ground fault is a high-resistance ground fault is displayed on the display unit 155. [Figure 3B] It is a diagram showing a state where an example of a change in the second current value having an amplitude smaller than the amplitude of the first current value that appears on the secondary side of the current transformer 123 when the ground fault is a high-resistance ground fault is displayed on the display unit 155. [Figure 3C] It is a diagram showing a state where waveforms of the second current value in FIG. 3B and the first current value in FIG. 3A are displayed in the upper and lower parts of the display unit 155, respectively. [Figure 4] It is a flowchart showing a process in which the arrival time detection unit 153 detects the surge arrival time when a ground fault occurs. [Figure 5] It is a diagram showing a method for标定 the ground fault point. [Figure 6] It is a block diagram showing an example of the hardware of the information processing apparatus 300 that realizes the functions of the ground fault point标定 device 150.

Mode for Carrying Out the Invention

[0018] From the description in this specification and the accompanying drawings, at least the following matters become clear. Hereinafter, the present invention will be described based on one embodiment thereof with reference to the accompanying drawings. In this embodiment, the same or similar configurations may be denoted by common reference numerals and their descriptions may be omitted. Also, in this embodiment, the letter "S" attached before the reference numeral means a processing step.

[0019] FIG. 1 is a block diagram showing a schematic configuration of a ground fault point标定 system 100 according to this embodiment.

[0020] The ground fault location system 100 is a system that identifies the ground fault location when a ground fault such as a low-resistance ground fault or a high-resistance ground fault occurs in a distribution line 110 that is installed on multiple support poles 160 located between a substation (power source) and a customer area (load). The ground fault location system 100 comprises a plurality of voltage sensors 121, a plurality of current sensors 122, a plurality of current transformers 123, a plurality of measurement terminals 130, a plurality of battery terminals 140, and a ground fault location device 150 as means for locating the ground fault location.

[0021] A voltage sensor 121 is installed, for example, at each support pole 160 on which the power distribution line 110 is mounted. As the voltage sensor 121, for example, an instrument transformer PD (hereinafter referred to as "instrument transformer 121") that detects the voltage appearing in each phase of the power distribution line 110 can be used. When a ground fault occurs in the power distribution line 110, the instrument transformer 121 detects the zero-sequence voltage that appears in the power distribution line 110 at the location where the support pole 160 is installed. The output of the instrument transformer 121 is supplied directly to the measurement terminal 130.

[0022] The current sensor 122 is installed on each support pole 160 in a one-to-one correspondence with the instrument transformer 121 installed on the support pole 160. As the current sensor 122, for example, a zero-sequence current transformer ZCT (hereinafter referred to as "zero-sequence current transformer 122") can be used, which detects the zero-sequence current by combining the currents flowing through all phases (R phase, S phase, T phase) of the distribution line 110. The zero-sequence current transformer 122 detects the surge current flowing through the distribution line 110 when a ground fault occurs at the location of the support pole 160, due to the disruption of the balance of zero-sequence currents in all phases accompanying the generation of ground fault current (leakage current). When a surge current occurs, a zero-sequence voltage is generated because all phases become unbalanced.

[0023] A current transformer 123 is installed on each support column 160 so as to correspond one-to-one with a zero-phase current transformer 122 installed on the support column 160. The output of the zero-phase current transformer 122 is supplied directly to the measurement terminal 130 and also supplied to the measurement terminal 130 via the current transformer 123. Here, if the current value of the surge current detected by the zero-phase current transformer 122 is called the first current value, the current transformer 123 converts the current value of the surge current so that the first current value supplied to the primary side appears on the secondary side as a second current value with an amplitude smaller than that of the first current value. In this way, the measurement terminal 130 receives information indicating both the first current value before conversion by the current transformer 123 and the second current value after conversion by the current transformer 123 simultaneously.

[0024] In the current transformer 123, the number of turns of the coil wound on the primary side of the iron core and the number of turns of the coil wound on the secondary side of the iron core are determined such that when the current value on the primary side is the first current value, the current value on the secondary side becomes the second current value.

[0025] For example, if a ground fault is a low-resistance ground fault, the surge current rises sharply, and the amplitude of the surge current becomes extremely large. Therefore, if the surge current remains at the first current value, when the waveform of the surge current is displayed on the display unit 155, the initial peak value of the surge current may fall outside the display area of ​​the display unit 155. On the other hand, if the surge current is converted from the first current value to the second current value, the initial peak value of the surge current may fall within the display area of ​​the display unit 155. For these reasons, the number of turns of the coils on the primary and secondary sides of the current transformer 123 is determined so that when a low-resistance ground fault occurs, the initial peak value of the surge current converted from the first current value to the second current value can be displayed on the display unit 155. The number of turns of the coils on the primary and secondary sides of the current transformer 123 is determined by verifying the current values ​​of surge currents in various low-resistance ground faults that have occurred in the past.

[0026] The sensor switch 120 is installed, for example, at each support pole 160. The sensor switch 120 houses the instrument transformer 121, zero-phase current transformer 122, and current transformer 123 in a sealed state inside the casing in order to protect them from external factors such as wind, rain, and ultraviolet rays. In this embodiment, the instrument transformer 121 and zero-phase current transformer 122 are used not only in the ground fault location system 100 but also in the 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 instrument transformer 121 and zero-phase current transformer 122, thereby isolating the fault section from the healthy section. Furthermore, the instrument transformer 121 and the zero-phase current transformer 122 may be used only in the ground fault location system 100.

[0027] The measurement terminal 130 is installed on each support pole 160 so as to correspond one-to-one with the combination of instrument transformer 121, zero-phase current transformer 122, and current transformer 123 installed on the pole. The measurement terminal 130 consists of a GPS receiver 131, a timer 132, and a memory 133. The measurement terminal 130 is connected to the instrument transformer 121, zero-phase current transformer 122, and current transformer 123 and receives information indicating the zero-phase voltage detected by the instrument transformer 121, the current value of the surge current detected by the zero-phase current transformer 122 (first current value), and the current value of the surge current appearing on the secondary side of the current transformer 123 (second current value). When a ground fault occurs in the power distribution line 110, the zero-sequence voltage changes and a surge current is generated. Therefore, in this embodiment, the measurement terminal 130 controls the storage operation of the memory 133 in response to the change in zero-sequence voltage when a ground fault occurs in the power distribution line 110.

[0028] A battery terminal 140 is installed on each support pole 160 so as to correspond one-to-one with a 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 is composed of, for example, a lead-acid battery, a lithium-ion battery, a sodium-sulfur battery, a nickel-metal hydride battery, a redox flow battery, a fuel cell, a capacitor battery, etc. As a result, the measurement terminal 130 operates using the power supplied to the distribution line 110, and when the power supplied to the distribution line 110 is interrupted, it operates using the power stored in the battery 134.

[0029] The GPS satellite 170 is an artificial satellite with an orbital altitude of, for example, several hundred to tens of thousands of kilometers, and transmits radio waves (microwaves) containing orbital information and time information toward the Earth at regular intervals (e.g., once per second). The GPS receiver 131 receives the time information contained in the radio waves transmitted from the GPS satellite 170. The timer 132 measures the time accurately in synchronization with the time information received by the GPS receiver 131. Regardless of whether a ground fault occurs in the power distribution line 110, the memory 133 continues to store the first current value supplied to the primary side of the current transformer 123 and the second current value appearing on the secondary side of the current transformer 123 in memory area A at predetermined intervals (e.g., 50 nsec) in association with the time measured by the timer 132. When a ground fault occurs in the power distribution line 110, memory 133 reads from storage area A the information that associates time with the first current value and the second current value for the period TA+TB, which includes the period TA before the zero-sequence voltage changes and the period TB after the zero-sequence voltage changes (hereinafter referred to as "fault information"), and stores it in storage area B. A data logger can be used as a device to perform data writing and reading operations to memory 133. When a ground fault occurs in the power distribution line 110, the measurement terminal 130 converts the fault information stored in storage area B of memory 133 into a text file in format such as CSV (Comma Separated Value), divides it into packets of a certain size, and transmits it to the ground fault location device 150.

[0030] The ground fault location device 150 is a computer or similar device that determines the location of a ground fault in the distribution line 110 when a ground fault occurs in the distribution line 110, and is installed, for example, by a power company.

[0031] The ground fault location device 150 is connected to multiple measurement terminals 130 via a communication network 180, enabling bidirectional communication. The communication network 180 can be, for example, a LAN (Local Area Network), a WAN (Wide Area Network), a dedicated line, a power line communication network, or various public communication networks.

[0032] The ground fault location device 150 is configured to include a fault information receiving unit 151, a ground fault fault determination unit 152, an arrival time detection unit 153, a ground fault location unit 154, a display unit 155, and a storage unit 156 as means for locating the ground fault location.

[0033] When a ground fault occurs in the power distribution line 110, the fault information receiving unit 151 receives fault information from multiple measurement terminals 130 via the communication network 180.

[0034] The ground fault determination unit 152 determines whether the ground fault is a low-resistance ground fault or a high-resistance ground fault based on the first current value included in the fault information, that is, the current value of the surge current as detected by the zero-sequence current transformer 122, in other words, the current value of the surge current before it is transformed by the current transformer 123 and supplied to the primary side of the current transformer 123. In a high-resistance ground fault, the first current value changes more slowly and is smaller than in the case of a low-resistance ground fault.

[0035] Figure 2A shows an example of the change in the first current value detected by the zero-phase current transformer 122 when the ground fault is a low-resistance ground fault, as displayed on the display unit 155. Note that the first peak value that appears after a low-resistance ground fault occurs does not fit within the display area of ​​the display unit 155 and is therefore not displayed.

[0036] Figure 2B shows an example of the change in the second current value, which has a smaller amplitude than the first current value, appearing on the secondary side of the current transformer 123 when the ground fault is a low-resistance ground fault, as displayed on the display unit 155. Note that the waveform of the second current value shown in Figure 2B corresponds to the waveform of the first current value shown in Figure 2A. Since the amplitude of the second current value is transformed by the current transformer 123 to be smaller than the amplitude of the first current value, the first peak value that appears in the second current value after a low-resistance ground fault occurs will be displayed within the display area of ​​the display unit 155.

[0037] In this embodiment, for the sake of explanation, the waveforms of the first and second current values ​​actually displayed on the display unit 155 when a low-resistance ground fault occurs are assumed to be, for example, the waveform in which the first positive peak value appears after the ground fault occurs. Alternatively, as shown in Figure 2C, the display area of ​​the display unit 155 may be divided into two sections, for example, vertically, with the waveform of the first current value shown in Figure 2A displayed in the lower display area 155A of the display unit 155, and the waveform of the second current value shown in Figure 2B displayed in the upper display area 155B of the display unit 155, on the same time axis as Figure 2A.

[0038] In Figures 2A and 2C, the horizontal axis represents time (nsec), and the vertical axis represents current (mA). The scale of the horizontal axis in Figures 2A and 2B is the same. Comparing the scales of the vertical axis in Figures 2A and 2B, the vertical axis scale in Figure 2B is compressed compared to that in Figure 2A so that the first peak value appearing in the second current value when a low-resistance ground fault occurs can be confirmed on the display unit 155. Furthermore, in both Figures 2A and 2B, the range of change in the positive and negative directions of the first and second surge current values ​​that can be displayed on the display unit 155 is the same. When a ground fault occurs, the direction in which the first and second current values ​​included in the fault information acquired from the measurement terminal 130 change first will be either positive or negative, depending on whether the surge current flows from the ground fault location towards the measurement terminal 130 on the substation side or towards the measurement terminal 130 on the opposite side of the substation. In this embodiment, when a low-resistance ground fault occurs, the direction in which the first and second current values ​​included in the fault information change first is assumed to be positive.

[0039] On the other hand, Figure 3A shows an example of the change in the first current value detected by the zero-phase current transformer 122 when the ground fault is a high-resistance ground fault, as displayed on the display unit 155. Note that the first peak value that appears after the occurrence of a high-resistance ground fault in the first current value displayed on the display unit 155 is displayed within the display area of ​​the display unit 155.

[0040] Figure 3B shows an example of a change in the second current value, which has a smaller amplitude than the first current value, appearing on the secondary side of the current transformer 123 when the ground fault is a high-resistance ground fault, as displayed on the display unit 155. Note that the waveform of the second current value shown in Figure 3B corresponds to the waveform of the first current value shown in Figure 3A.

[0041] In this embodiment, for the sake of explanation, the waveforms of the first and second current values ​​actually displayed on the display unit 155 when a high-resistance ground fault occurs are assumed to be, for example, the waveform in which the first negative peak value appears after the ground fault occurs. Alternatively, as shown in Figure 3C, the display area of ​​the display unit 155 may be divided into two sections, for example, vertically, with the waveform of the first current value shown in Figure 3A displayed in the lower display area 155A of the display unit 155, and the waveform of the second current value shown in Figure 3B displayed in the upper display area 155B of the display unit 155, on the same time axis as Figure 3A.

[0042] In Figures 3A and 3C, the horizontal axis represents time (nsec), and the vertical axis represents current (mA). The scale of the horizontal axis in Figures 3A and 3B is the same. The scale of the vertical axis in Figures 3A and 3B is the same as the scale of the vertical axis in Figures 2A and 2B, respectively. In Figures 3A and 3B, the range of change in the positive and negative directions of the first and second surge current values ​​that can be displayed on the display unit 155 is the same. When a ground fault occurs, the direction in which the first and second surge current values ​​included in the fault information acquired from the measurement terminal 130 change first will be either positive or negative, depending on whether the surge current flows from the ground fault location towards the measurement terminal 130 on the substation side, or from the ground fault location towards the measurement terminal 130 on the opposite side of the substation. In this embodiment, when a high-resistance ground fault occurs, the first direction in which the first current value and the second current value included in the fault information change is assumed to be the positive direction.

[0043] When a low-resistance ground fault or a high-resistance ground fault occurs, the waveforms of the first and second current values ​​may be displayed using the same display unit 155, or two separate display units 155 may be provided to display them individually.

[0044] The ground fault determination unit 152 determines whether a ground fault is caused by a low-resistance ground fault or a high-resistance ground fault by comparing the first current value included in the fault information with a predetermined threshold. Specifically, if the absolute value of the first peak value that appears in the first current value when a ground fault occurs is greater than the threshold, and this peak value is outside the display area of ​​the display unit 155 and cannot be confirmed, the ground fault determination unit 152 determines that this ground fault is caused by a low-resistance ground fault. On the other hand, if the absolute value of the first peak value that appears in the first current value when a ground fault occurs is less than the threshold, and either the positive peak value when rising from a positive direction to a negative direction or the negative peak value when rising from a negative direction to a positive direction can be confirmed in the display area of ​​the display unit 155, the ground fault determination unit 152 determines that this ground fault is caused by a high-resistance ground fault. The threshold value is predetermined, for example based on empirical rules, so that it is greater than the absolute value of the first peak value that appears in the first current value when the ground fault is a high-resistance ground fault.

[0045] The following describes an example of setting the thresholds mentioned above. If the ground fault is a low-resistance ground fault, the first peak value that appears in the first current value will not fit within the display range of the display unit 155, making it impossible to check on the display unit 155. On the other hand, if the ground fault is a high-resistance ground fault, the first peak value that appears in the first current value will fit within the display range of the display unit 155, making it possible to check on the display unit 155. For example, if the absolute value of the range of change in the positive and negative directions of the first current value that can be displayed in the display area of ​​the display unit 155 is set as the threshold, the ground fault determination unit 152 will determine that the ground fault is a low-resistance ground fault when the first peak value in the first current value is not displayed on the display unit 155, and will determine that the ground fault is a high-resistance ground fault when the first peak value in the first current value is displayed on the display unit 155.

[0046] Based on the determination result of the ground fault determination unit 152, the arrival time detection unit 153 uses a second current value obtained from the measurement terminal 130 if it is determined that the ground fault is a low-resistance ground fault, and uses a first current value obtained from the measurement terminal 130 if it is determined that the ground fault is a high-resistance ground fault, to detect the surge arrival time, which is the time when the surge current at the time the ground fault occurred reaches the measurement terminal 130, using the "peak value detection method" described later.

[0047] For example, when the arrival time detection unit 153 obtains a determination result from the ground fault determination unit 152 indicating that the ground fault is either a low-resistance ground fault or a high-resistance ground fault, it detects the surge arrival time as shown below using the peak value detection algorithm set in the arrival time detection unit 153.

[0048] Figure 4 is a flowchart showing the process by which the arrival time detection unit 153 detects the surge arrival time when a ground fault occurs.

[0049] First, the arrival time detection unit 153 determines whether a surge current is generated due to an imbalance in the zero-sequence current caused by a ground fault (S1010).

[0050] In the case of a low-resistance ground fault, as shown in Figure 2B, during period TA before the zero-sequence voltage changes due to the ground fault, the zero-sequence current is around 0mA with a small amount of constant noise superimposed. The arrival time detection unit 153 detects the amplitude of the constant noise generated during period TA and sets a first threshold +Ith1 that is larger than the constant noise on the positive side, and a second threshold -Ith1 that is smaller than the constant noise on the negative side. As a result, the arrival time detection unit 153 determines that during period TA, the constant noise is neither larger than the first threshold +Ith1 nor smaller than the second threshold -Ith1, and therefore no surge current is generated due to the ground fault (S1010:NO). On the other hand, in the case of a high-resistance ground fault, as shown in Figure 3A, during period TA before the zero-sequence voltage changes due to the ground fault, the zero-sequence current is around 0mA with a small amount of constant noise superimposed. The arrival time detection unit 153 detects the amplitude of the constant noise occurring during period TA and sets a first threshold +Ith2 that is greater than the constant noise on the positive side, and a second threshold -Ith2 that is smaller than the constant noise on the negative side. As a result, the arrival time detection unit 153 determines that during period TA, the constant noise is neither greater than the first threshold +Ith2 nor less than the second threshold -Ith2, and therefore no surge current associated with a ground fault occurs (S1010: NO). The arrival time detection unit 153 then repeatedly executes the process in step S1010 until it detects the occurrence of a surge current associated with a ground fault.

[0051] If the surge current changes as shown in Figure 2B, during the period TB after the zero-sequence voltage changes due to the ground fault, the zero-sequence current will be unbalanced across all phases and will begin to change in the positive direction, exceeding the first threshold +Ith1. The arrival time detection unit 153 determines that the surge current is caused by the ground fault when the zero-sequence current becomes larger than the first threshold +Ith1 (S1010:YES). On the other hand, if the surge current changes as shown in Figure 3A, during the period TB after the zero-sequence voltage changes due to the ground fault, the zero-sequence current will be unbalanced across all phases and will begin to change in the negative direction, falling below the second threshold -Ith2. The arrival time detection unit 153 determines that the surge current is caused by the ground fault when the zero-sequence current becomes smaller than the second threshold -Ith2 (S1010:YES).

[0052] Next, if the arrival time detection unit 153 obtains a determination result from the ground fault determination unit 152 indicating that the ground fault is a low-resistance ground fault (S1020: YES), it selects the second current value from the first and second current values ​​obtained from the measurement terminal 130 (S1030). On the other hand, if the arrival time detection unit 153 does not obtain a determination result from the ground fault determination unit 152 indicating that the ground fault is a low-resistance ground fault (S1020: NO) and obtains a determination result indicating that the ground fault is a high-resistance ground fault (S1040: YES), it selects the first current value from the first and second current values ​​obtained from the measurement terminal 130 (S1050). If the arrival time detection unit 153 has not obtained a determination result indicating either a low-resistance ground fault or a high-resistance ground fault (S1040: NO), it returns to the process of step S1020 and executes it again.

[0053] If the ground fault is a low-resistance ground fault and a second current value is selected (S1030), the arrival time detection unit 153 performs processing to detect the so-called positive peak value, which occurs when the zero-sequence current becomes greater than the first threshold + Ith1, and the surge current then changes from an upward movement in the positive direction to a downward movement in the negative direction (S1060). For example, the arrival time detection unit 153 converts the current value of the surge current for the period TB included in the fault information into an absolute value and detects the first absolute value that is maximum within the period TB. This absolute value becomes the positive peak value of the surge current.

[0054] On the other hand, if the ground fault is a high-resistance ground fault and the first current value is selected (S1050), the arrival time detection unit 153 performs processing to detect the so-called negative peak value, which occurs when the surge current first changes from a decrease in the negative direction to an increase in the positive direction, because the zero-sequence current has become smaller than the second threshold -Ith2 (S1060). For example, the arrival time detection unit 153 converts the current value of the surge current for the period TB included in the fault information into an absolute value and detects the first absolute value that is maximum within the period TB. This absolute value becomes the negative peak value of the surge current.

[0055] Next, the arrival time detection unit 153 considers the time on the horizontal axis where the peak value obtained in step S1060 appears as the surge arrival time at each measurement terminal 130 (S1070).

[0056] In this way, the arrival time detection unit 153 determines the surge arrival time in both low-resistance and high-resistance ground fault cases in a manner that minimizes the error in determining the fault point.

[0057] Figure 5 shows a method for locating the ground fault point. The surge arrival time shown by this method is the surge arrival time determined by the arrival time detection unit 153 according to the peak value detection method.

[0058] The ground fault location unit 154 uses a total of three measurement terminals: one 130A located on the substation side of the ground fault location, and two 130B and 130C located on the customer area side of the ground fault location; or two 130A and 130B located on the substation side of the ground fault location, and one 130C located on the customer area side of the ground fault location, to locate the ground fault location.

[0059] For the sake of explanation, the location where a ground fault occurs in the distribution line 110 is assumed to be a predetermined position (marked with an "x") between measurement terminal 130A, which is on the substation side of the ground fault point, and measurement terminal 130B, which is on the consumer area side of the ground fault point. In other words, among the combinations of two measurement terminals 130 that straddle the ground fault point, the surge arrival time for the adjacent combination of measurement terminals 130A and 130B will be earlier than the surge arrival time for other combinations of the two measurement terminals 130. Alternatively, the ground fault location device 150 can also identify between which measurement terminals 130 the ground fault occurred by determining whether the surge current obtained from the three measurement terminals 130A, 130B, and 130C is positive or negative. Here, let X be the distance between the ground fault point and measurement terminal 130A. Let Lab be the distance between measurement terminals 130A and 130B, and Lac be the distance between measurement terminals 130A and 130C. Furthermore, since the surge current flows radially through the distribution line 110 toward the measurement terminals 130A, 103B, and 130C, the surge propagation speed at this time (first propagation speed) is denoted as U1. Also, the surge arrival times when the surge current reaches the measurement terminals 130A, 130B, and 130C from the ground fault point are denoted as ta1, tb1, and tc1, respectively.

[0060] Using the distance Lab between measurement terminals 130A and 130B, and the surge arrival times ta1 and tb1 when the surge current reaches measurement terminals 130A and 130B, the distance X between the ground fault point and measurement terminal 130A is: X=(Lab / 2)+(ta1-tb1)U1 / 2 ···(1) This is shown.

[0061] Furthermore, using the distance Lac between measurement terminals 130A and 130C, and the surge arrival times ta1 and tc1 when the surge current reaches measurement terminals 130A and 130C, the distance X between the ground fault point and measurement terminal 130A is: X=(Lac / 2)+(ta1-tc1)U1 / 2 ···(2) This is shown.

[0062] By solving the simultaneous equations (1) and (2), the distance X between the ground fault point and the measurement terminal 130A can be calculated.

[0063] If the ground fault is caused by a low-resistance ground fault, the second current value is selected as the surge current value. On the other hand, if the ground fault is caused by a high-resistance ground fault, the first current value is selected as the surge current value. By defining the time when the surge current first reaches its peak value within the period TB from the detection of the surge current as the surge arrival time, it becomes possible to locate the ground fault point with a small assessment error in both low-resistance and high-resistance ground faults. As a result, the burden on workers during patrol work until the ground fault location is discovered can be significantly reduced.

[0064] The memory unit 156 stores information such as the control program for the ground fault location device 150 to locate the ground fault location, fault information received by the fault information receiving unit 151, the type of ground fault determined by the ground fault determination unit 152 (low-resistance ground fault, high-resistance ground fault), the surge arrival time detected by the arrival time detection unit 153, and the ground fault location determined by the ground fault location location unit 154.

[0065] Figure 6 is a block diagram showing an example of the hardware of an information processing device 300 that implements the functions of the ground fault location device 150 shown in Figure 1.

[0066] The information processing device 300 comprises a processor 310, main memory 320, auxiliary memory 330, input device 340, output device 350, and 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. The information processing device 300 may be implemented in whole or in part using virtual information processing resources provided using virtualization technology, such as a virtual server provided by a cloud system.

[0067] The processor 310 is composed of components such as a CPU (Central Processing Unit), MPU (Micro Processing Unit), GPU (Graphics Processing Unit), FPGA (Field Programmable Gate Array), ASIC (Application Specific Integrated Circuit), and AI (Artificial Intelligence) chip.

[0068] The main memory 320 is a device for storing programs and data, and can be, for example, ROM (Read Only Memory), RAM (Random Access Memory), or non-volatile memory (NVRAM (Non-Volatile RAM)).

[0069] The auxiliary storage device 330 is, for example, an SSD (Solid State Drive), a hard disk drive, an optical storage device (CD (Compact Disc), DVD (Digital Versatile Disc), etc.), a storage system, an IC card, an SD card, a reader / writer for optical storage media, or the storage area of ​​a cloud server. Programs and data can be read into the auxiliary storage device 330 via a storage media reader or a communication device 360. Programs and data stored in the auxiliary storage device 330 are read into the main memory 320 as needed.

[0070] The input device 340 is an interface that accepts input from an external source, and can be, for example, a keyboard, mouse, touch panel, card reader, pen-input tablet, or voice input device.

[0071] The output device 350 is an interface that outputs various information such as processing progress and processing results. The output device 350 may be, for example, a display device that visualizes the above information (LCD (Liquid Crystal Display), graphics card, etc.), a device that converts the above information into sound (speaker, etc.), or a device that converts the above information into text (printer, etc.). The information processing device 300 may also be configured to input and output information to and from other devices via the communication device 360.

[0072] The input device 340 and the output device 350 constitute a user interface for receiving and presenting information with the user.

[0073] The communication device 360 ​​is a device that enables communication (wired 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.

[0074] Furthermore, the information processing device 300 may have, for example, an operating system, a file system, a DBMS (Database Management System) (relational database, NoSQL, etc.), a KVS (Key-Value Store), etc. installed on it.

[0075] The functions of the ground fault location device 150 are realized either by the processor 310 of the information processing device 300 reading and executing a control program stored in the main memory 320, or by the functions of the hardware (FPGA, ASIC, AI chip, etc.) that constitutes the information processing device 300 itself. In this embodiment, the functions of the storage unit 156 of the ground fault location device 150 are realized by the main memory 320 and auxiliary memory 330 of the information processing device 300, while the functions of the fault information receiving unit 151, ground fault fault determination unit 152, arrival time detection unit 153, and ground fault location unit 154 of the ground fault location device 150 are realized by the processor 310 of the information processing device 300 operating according to a control program. Furthermore, the fault information receiving unit 151 of the ground fault location 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 ground fault location device 150 is realized by the processor 310 of the information processing device 300 controlling the output device 350.

[0076] As described above, the information processing device 300, which has a processor 310 and a memory device (main memory device 320 and auxiliary memory device 330), acquires fault information from multiple measurement terminals 130 installed at multiple points along the power distribution line 110, including a first current value which is the current value of the surge current when the power distribution line 110 has a ground fault, and a second current value obtained based on the first current value and having an amplitude smaller than the amplitude of the first current value. When the amplitude of the first current value is greater than or equal to a predetermined threshold, the time when the second current value first reaches its peak value is determined for each point as the surge arrival time when the surge current reaches the multiple measurement terminals 130, and the ground fault point where the ground fault occurred is determined based on the difference in surge arrival times between adjacent points.

[0077] According to the information processing device 300, in addition to the first current value, a second current value with an amplitude smaller than that of the first current value is also acquired as the current value of the surge current. For example, even in the case of a low-resistance ground fault, by setting the time when the second current value first reaches its peak value as the surge arrival time, it becomes possible to accurately pinpoint the ground fault point and detect the ground fault early.

[0078] Furthermore, in the information processing device 300, the first current value is the value of the surge current input to the primary side of multiple current transformers 123 installed at multiple locations, and the second current value is the value of the surge current output from the secondary side of the multiple current transformers 123.

[0079] According to the information processing device 300, since the first current value and the second current value output from the current transformer 123 are acquired simultaneously, it is possible to display the first current value and the second current value side by side on the display unit.

[0080] Furthermore, in the information processing device 300, the first current value is the surge current value when the distribution line 110 experiences a low-resistance ground fault. The first current value has an amplitude where the peak value of the first current value exceeds the display range of the display unit 155, and the second current value has an amplitude where the peak value of the second current value is displayed within the display range of the display unit 155.

[0081] According to the information processing device 300, when a low-resistance ground fault occurs, the first current value and the second current value can be simultaneously checked on the display unit.

[0082] This embodiment is provided to facilitate understanding of the present invention and is not intended to limit its interpretation. The present invention may be modified or improved without departing from its spirit, and equivalents thereof are also included. [Explanation of Symbols]

[0083] 100 Ground Fault Location System 110 Power distribution lines 120 Sensor switch 121 Instrument transformer 122 Zero phase current transformer 123 Current Transformer 130 measuring terminals 131 GPS receiver 132 timers 133 memory 140 Battery Terminals 150 Ground fault location device 151 Accident Information Receiving Unit 152 Ground Fault Accident Determination Unit 153 Arrival Time Detection Unit 154 Ground fault location unit 155 Display section 155A, 155B display area 160 Post 170 GPS satellites 180 Communication Networks 300 Information Processing Devices 310 Processor 320 Main storage 330 Auxiliary storage device 340 Input Devices 350 Output device 360 Communication device

Claims

1. It has a processor and a storage device, From multiple measurement terminals installed at multiple points on the power distribution line, fault information is acquired including a first current value, which is the current value of the surge current when the power distribution line experiences a ground fault, and a second current value obtained based on the first current value, which has an amplitude smaller than the amplitude of the first current value. When the amplitude of the first current value is greater than or equal to a predetermined threshold, the time at which the second current value first reaches its peak value is determined for each location as the surge arrival time when the surge current reaches the plurality of measurement terminals. Based on the difference in the surge arrival times between adjacent points, the fault point where the ground fault occurred is determined. Information processing device.

2. An information processing apparatus according to claim 1, The first current value is the value of the surge current input to the primary side of the multiple current transformers installed at the multiple locations. The second current value is the value of the surge current output from the secondary side of the plurality of current transformers. Information processing device.

3. An information processing apparatus according to claim 2, The first current value is the surge current value when the distribution line experiences a low-resistance ground fault. Information processing device.

4. An information processing apparatus according to claim 3, The first current value has an amplitude in which the peak value of the first current value exceeds the display range of the display unit. The second current value has an amplitude in which the peak value of the second current value is displayed within the display range of the display unit. Information processing device.

5. An information processing device having a processor and a memory device, From multiple measurement terminals installed at multiple points on the power distribution line, fault information is acquired including a first current value, which is the current value of the surge current when the power distribution line experiences a ground fault, and a second current value obtained based on the first current value, which has an amplitude smaller than the amplitude of the first current value. When the amplitude of the first current value is greater than or equal to a predetermined threshold, the time at which the second current value first reaches its peak value is determined for each location as the surge arrival time when the surge current reaches the plurality of measurement terminals. Based on the difference in the surge arrival times between adjacent points, the fault point where the ground fault occurred is determined. Information processing methods.

6. The information processing method according to claim 5, The first current value is the value of the surge current input to the primary side of the multiple current transformers installed at the multiple locations. The second current value is the value of the surge current output from the secondary side of the plurality of current transformers. Information processing methods.

7. The information processing method according to claim 6, The first current value is the surge current value when the distribution line experiences a low-resistance ground fault. Information processing methods.

8. The information processing method according to claim 7, The first current value has an amplitude in which the peak value of the first current value exceeds the display range of the display unit. The second current value has an amplitude in which the peak value of the second current value is displayed within the display range of the display unit. Information processing methods.

9. A computer having a processor and memory, A process for acquiring fault information from multiple measurement terminals installed at multiple points on a power distribution line, including a first current value which is the current value of the surge current when the power distribution line experiences a ground fault, and a second current value obtained based on the first current value and having an amplitude smaller than the amplitude of the first current value, When the amplitude of the first current value is greater than or equal to a predetermined threshold, the time at which the second current value first reaches its peak value is determined for each of the multiple measurement terminals as the surge arrival time, and the process is as follows: A process to locate the fault point where the ground fault occurred based on the difference in surge arrival times between adjacent points, A program that executes the command.

10. Multiple measurement terminals are installed at multiple points on a power distribution line to measure a first current value, which is the current value of the surge current when the power distribution line experiences a ground fault, and to store fault information including the first current value and a second current value obtained based on the first current value, which has an amplitude smaller than the amplitude of the first current value. An information processing device having a processor and a memory device, which acquires fault information from the plurality of measurement terminals, and when the amplitude of the first current value is greater than or equal to a predetermined threshold, determines for each location the time when the surge current reaches the plurality of measurement terminals as the surge arrival time, and identifies the fault point where the ground fault occurred based on the difference in the surge arrival times between adjacent locations, A ground fault location system equipped with the following features.

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