JP2018205109A - Ground point localization system - Google Patents

Abstract

To provide a ground point localization system that can identify a ground fault point even for a minute ground fault current.SOLUTION: This invention includes a plurality of sensors having a winding core formed in an annular shape such that a magnetic flux density of a magnetic flux generated when the ground fault current flows through a power line of a power system becomes equal to or less than a predetermined magnetic flux density value, and a coil wound around the winding core through which the electric power line is passed; a comparison specifying unit for specifying a second ground fault current indicating a current value smaller than a first ground fault current indicating the highest current value among the ground fault currents detected by each of the plurality of sensors; an amplification unit for amplifying a ground fault current waveform corresponding to a second ground fault current identified by the comparison specifying unit; and ground point localization unit identifying a change point representing a generation time of the second ground fault current in the ground fault current waveform amplified by the amplifying unit and showing the point at which the ground fault current in the power system is generated based on the change point.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a ground fault location system.

  For example, a current detection sensor for detecting a ground fault point when a ground fault occurs in a power system is known. (For example, patent document 1).

JP-A-5-268723 JP 2004-132762 A

  Patent Document 1 discloses a method for determining whether or not a ground fault has occurred in the ground fault detection unit section by detecting the phase of the zero-phase current in the ground fault detection unit section. However, in the method according to Patent Document 1, although it is possible to determine whether or not a ground fault has occurred in the ground fault detection unit section, it is possible to identify at which point in the ground fault detection unit section the ground fault has occurred. Therefore, it may take time to specify the ground fault point.

  Further, Patent Document 2 discloses a system for determining a ground fault point by calculating a difference in surge arrival time at each point by detecting a zero-phase current and a zero-phase voltage of a transmission and distribution line. . The system has a function of calculating the surge arrival time based on the waveform data of the zero-phase current and the time data indicating the time point when the sudden change in the zero-phase voltage is detected. However, in the system according to Patent Document 2, although it works for a ground fault accident with a large surge current such that a circuit breaker of a substation operates, a ground fault accident with a small surge current such that the circuit breaker does not operate. On the other hand, there was a possibility that the ground fault point could not be specified.

  The main present invention for solving the above-mentioned problems is that the core formed in an annular shape so that the magnetic flux density of the magnetic flux generated when the ground fault current flows through the power line of the power system is a predetermined magnetic flux density value or less, A plurality of sensors having a coil wound around the winding core through which the power line passes to detect the ground fault current, and the largest current value among the ground fault currents detected by each of the plurality of sensors. A comparison and identification unit that identifies a second ground fault current that indicates a current value smaller than the first ground fault current that indicates and a ground fault current waveform that corresponds to the second ground fault current that is identified by the comparison and identification unit And a change point representing a generation time of the second ground fault current in the ground fault current waveform amplified by the amplifier, and based on the change point, the ground fault in the power system Ground fault point indicating the point where the current occurred Characterized in that it comprises a and the earth 絡点 orientation section for orientation.

  Other features of the present invention will become apparent from the accompanying drawings and the description of this specification.

  According to the present invention, it is possible to specify a ground fault point even for a small ground fault current.

It is a figure which shows the ground fault location system which concerns on this embodiment. It is a figure which shows the sensor box which concerns on this embodiment. It is a figure which shows the sensor for electric current detection which concerns on this embodiment. It is a figure which shows the characteristic of the core which concerns on this embodiment. It is a figure which shows the characteristic of the core which concerns on this embodiment. It is a figure which shows an example of a structure of the ground fault point location apparatus which concerns on this embodiment. It is a figure which shows the operation | movement flow of the ground fault location system which concerns on this embodiment. It is a figure which shows an example of the ground fault current waveform of the 1st and 2nd current detection apparatus which concerns on this embodiment. It is a figure which shows an example which amplified the gain of the ground fault current waveform of the 2nd current detection apparatus which concerns on this embodiment. It is a figure which shows an example of the ground fault current waveform of the 1st and 2nd current detection apparatus which concerns on this embodiment. It is a figure which shows an example which amplified the gain of the ground fault current waveform of the 1st and 2nd current detection apparatus which concerns on this embodiment.

  At least the following matters will become apparent from the description of this specification and the accompanying drawings. In the following description, parts denoted by the same reference numerals represent the same elements, and the basic configuration and operation thereof are the same.

=== Ground fault location system 100 ===
The ground fault location system 100 will be described as follows with reference to FIG. FIG. 1 is a diagram showing a ground fault location system 100 according to the present embodiment.

  The ground fault location system 100 is a system for locating a location (hereinafter referred to as “ground fault point P”) where a ground fault has occurred in the power system (22 kV distribution system in this embodiment). As shown in FIG. 1, the ground fault location system 100 includes a first current detection device 110 provided on the power supply side, a second current detection device 120 provided on the load side, and a ground fault point P in the power system. And a ground fault point locating device 130 for locating. In FIG. 1, for convenience of explanation, two units of the first current detection device 110 and the second current detection device 120 are shown to be provided in the power system, but the current detection devices are provided in excess of two units. May be.

== First and second current detectors 110, 120 ==
The first and second current detection devices 110 and 120 will be described as follows with reference to FIGS. 2, 3, 4, and 5. FIG. 2 is a diagram illustrating the sensor box 112 according to the present embodiment. FIG. 3 is a diagram showing a current detection sensor 111 according to the present embodiment. 4 and 5 are diagrams illustrating characteristics of the core 111a according to the present embodiment. In the following description, the first current detection device 110 is typically described, but the same applies to the second current detection device 120, and the same applies to a current detection device (not shown).

  The first current detection device 110 is a device that is installed in the power system and measures a physical quantity that varies according to the power state of the power system. The first current detection device 110 includes, for example, a sensor 111 that measures a physical quantity that varies according to the power state of the power system including the current or voltage of the distribution line 300, a sensor box 112 that houses the sensor 111, and a sensor 111. And a measurement terminal 113 that transmits a measurement result to the ground fault location device 130.

  The physical quantity measured by the sensor 111 is basically described as a physical quantity such as a current or a voltage of the distribution line 300, but may include a power factor or a frequency. In the present embodiment, each measuring instrument for these physical quantities is collectively referred to as a sensor 111.

  In general, the extra high voltage power system has three phases, but in FIG. 1, only one distribution line 300 is shown for the sake of simplicity. Actually, as shown in FIG. 2, sensor boxes 112 are provided in the respective phases of the distribution line 300. Each sensor box 112 is attached to the distribution line 300 of each phase, and a physical quantity that varies according to the power state of the power system is measured by the sensor 111 accommodated in each sensor box 112.

  The measurement terminal 113 is a device that transmits the measured value of the physical quantity measured by the sensor 111 of each phase of the distribution line 300 to the ground fault location device 130 via the communication path 200.

  The measurement terminal 113 uses the physical quantity value of each phase of the distribution line 300 measured by the sensor 111 to calculate other physical quantity values that vary depending on the power state of the power system, and to determine the ground fault point location. It can also be transmitted to the device 130.

  For example, the measurement terminal 113 acquires a current value of each phase of the distribution line 300, combines the acquired current values, calculates a zero-phase current, and transmits it to the ground fault location device 130. Alternatively, the measurement terminal 113 acquires the voltage value of each phase of the distribution line 300, calculates the zero-phase voltage by combining the acquired voltage values, and transmits it to the ground fault location device 130. It is good.

  Since the measurement terminal 113 receives the current time from the GPS satellite 1000, the current value and voltage value measured by the measurement terminal 113, the calculated zero-phase current and zero-phase voltage, and time information are obtained. Correspondingly, it is transmitted to the ground fault location device 130. In the following, the zero-phase current may be described as a ground fault current.

  By the way, since the electric power system which concerns on this embodiment is a 22 kV distribution system, the resistance grounding system and the non-grounding system are employ | adopted for the grounding system of the transformer (not shown) provided in a substation (not shown). The resistance grounding method is a method in which a neutral point of the transformer and the ground are connected by a conductor via a resistor and grounded, and the non-grounding method is a method in which neutral point grounding is not performed.

  Therefore, when a ground fault occurs in the distribution line 300, the range of the ground fault current varies greatly depending on the difference in the grounding method of the transformer provided in the substation. For example, in the resistance grounding method, the neutral point is grounded by a resistor, so that the ground fault current is about several hundred A (ampere), and in the non-grounding method, it is about several tens mA (milliampere).

  Even in such a case, the sensor 111 according to the present embodiment is configured to detect a ground fault current regardless of whether the grounding method is a resistance grounding method or a non-grounding method. Yes.

  As shown in FIG. 3, the sensor 111 is wound so as to detect an annular winding core 111 a provided so as to penetrate the distribution line 300 and a ground fault current generated in the distribution line 300 when the distribution line 300 is grounded. A coil 111b wound around the core 111a. In the sensor 111, when a ground fault current flows through the distribution line 300, the magnetic flux Φ of the core 111a changes, and the current flowing through the coil 111b changes accordingly. By detecting the current flowing through the coil 111b with a detector (not shown), the ground fault current flowing through the distribution line 300 can be detected.

  Here, the core 111a is formed so that the magnetic flux density B of the magnetic flux generated when the ground fault current flows through the distribution line 300 is equal to or less than a predetermined magnetic flux density value. By forming the sensor 111 so that the magnetic flux density B of the magnetic flux generated in the core 111a is as small as possible, the range of the ground fault current that can be detected by the sensor 111 can be expanded. This makes it possible to detect a ground fault current regardless of whether the transformer grounding system of the 22 kV distribution system is a resistance grounding system or a non-grounding system.

  In other words, by reducing the magnetic flux density B of the magnetic flux generated in the winding core 111a to be equal to or less than a predetermined magnetic flux density value, it is possible to reduce the variation in the measured values of the sensors 111 attached to the distribution lines 300 of each phase. This makes it possible to measure the ground fault current over a wide band. Hereinafter, the core 111a will be described in more detail with reference to FIGS.

  FIG. 4 shows the relationship between the relative permeability μr of the core 111a and the magnetic flux density B of the magnetic flux generated in the core 111a. A characteristic curve when the core 111a is a permalloy core is illustrated, but it can be seen that the value of the relative permeability μr varies greatly depending on the magnetic flux density B. For this reason, in order to suppress variations in the characteristics of the sensors 111 of the respective phases, it is necessary to generate a magnetic flux density B in a range in which the variation of the relative permeability μr is as small as possible on the core 111a.

  Referring to FIG. 4, it can be seen that the smaller the magnetic flux density B, the smaller the variation in the relative permeability μr. Therefore, FIG. 5 shows an enlarged relationship between the magnetic flux density B and the relative permeability μr when the magnetic flux density B is 3000 gauss or less. The change in the relative permeability μr and the change in the magnetic flux density B are in a linear relationship, that is, the increase rate of the magnetic flux density B when the ground fault current flows through the distribution line 300 and the increase rate of the relative permeability μr coincide. For example, the change in the relative permeability μr is stabilized with respect to the change in the magnetic flux density B. The range of the magnetic flux density B in which the relative permeability μr is stable is an area where the variation of the sensors 111 of each phase is small.

  Referring to FIG. 5, it can be seen that the range in which the relative permeability μr increases linearly as the magnetic flux density B increases is a range in which the magnetic flux density B is a predetermined value or less. In the case shown in FIG. 5, a range where the magnetic flux density B is 1000 gauss or less is preferable. Of course, the change in the relative permeability μr and the change in the magnetic flux density B do not have to have a completely linear relationship, and each increase rate or change rate only needs to be within a predetermined range.

  As described above, the magnetic flux density B of the magnetic flux generated in the core 111a when the ground fault current flows through the distribution line 300 is determined based on the degree of change in the relative permeability μr with respect to the change in the magnetic flux density B. By making it below the value, the range of current that can be detected by the sensor 111 can be expanded, and even if the grounding system of the transformer of the 22 kV distribution system is either the resistance grounding system or the non-grounding system, It becomes possible to detect a ground fault current.

  In addition, the material used for the core 111a is determined by determining the above-described predetermined magnetic flux density value, which is the upper limit value of the magnetic flux density B, based on the degree of change in the relative permeability μr with respect to the change in the magnetic flux density B. The upper limit value of the magnetic flux density B can be determined based on the characteristics of the relative magnetic permeability μr and the magnetic flux density B as shown in FIG.

  The magnetic flux density B of the magnetic flux generated in the core 111a is proportional to the magnetic flux Φ, but is inversely proportional to the cross-sectional area S and the length (circumferential length) L of the core 111a. Therefore, the core 111a has a cross-sectional area S and a length L that are equal to or greater than a predetermined value so that the magnetic flux density B of the magnetic flux generated in the core 111a when the ground fault current is generated is suppressed to a predetermined magnetic flux density value or less. Need to be configured to be On the other hand, since there is a certain limit to the enlargement of the core 111a, the core 111a has a cross-sectional area such that the magnetic flux density B is suppressed to a predetermined magnetic flux density value or less, but becomes a certain lower limit value or more. It will be configured to have S and length L.

  Further, the current that flows through the coil 111b when the distribution line 300 is grounded is inversely proportional to the number of turns of the coil 111b. Therefore, the sensor 111 according to the present embodiment is determined such that the number of turns of the coil 111b is equal to or less than a predetermined number of turns. By setting the number of turns of the coil 111b to a predetermined number or less, even a weak ground fault current can be detected by increasing the secondary current level. Can be expanded.

  For example, when detecting a ground fault in an ungrounded power system, the distribution lines for each phase can be obtained without having to pierce the distribution lines 300 for three phases into one winding core 111a. Each of the sensors 111 is provided in 300, and a ground fault current of about several tens of mA can be detected.

  For this reason, it is possible to detect a ground fault current regardless of whether the transformer grounding system of the 22 kV distribution system is a resistance grounding system or a non-grounding system.

== Ground fault location device 130 ==
With reference to FIG. 6, the ground fault location device 130 will be described as follows. FIG. 6 is a diagram illustrating an example of the configuration of the ground fault location device 130 according to the present embodiment.

  The ground fault location device 130 detects the ground fault current generated when a ground fault occurs by the first and second current detection devices 110 and 120 described above, and amplifies the ground fault current to thereby detect the ground fault current. This is an apparatus for determining the ground fault point P by specifying the detection time of the fault current.

  The ground fault current generated by the ground fault of the distribution line 300 is attenuated as the propagation distance becomes longer. Therefore, when the distance from the ground fault point P to the point where the ground fault current is detected is long, it is difficult to detect the ground fault current. Therefore, the ground fault location device 130 detects the small ground fault current by using the first and second current detection devices 110 and 120 described above, and also detects the ground fault current waveform corresponding to the ground fault current. And the gain of the ground fault current waveform is amplified. Based on the amplified ground fault current waveform, a change point indicating the generation time of the ground fault current is specified, and the ground fault point P is determined based on the change point.

  As shown in FIG. 6, the ground fault location device 130 having such a function includes an arithmetic processing unit 131, a main storage unit 132, an input unit 133, an output unit 134, and an auxiliary storage unit 135. Each of which is configured to be communicable.

  The arithmetic processing unit 131 is composed of, for example, a CPU or MPU. The arithmetic processing unit 131 implements various functions by executing an instruction to read a program temporarily stored in the main storage unit 132 from the auxiliary storage unit 135 and reading / writing information. Each component of the arithmetic processing unit 131 will be described later in detail. The main storage unit 132 is configured by a volatile memory such as a RAM, for example. The input unit 133 is a network interface to which various information output from the current detection device is input via the communication path 200. The output unit 134 is a network interface that outputs various types of information to a communication network. The auxiliary storage unit 135 is a device that stores a program to be processed by the arithmetic processing unit 131. The auxiliary storage unit 135 is configured by a nonvolatile memory such as a hard disk drive, an SSD, or an optical storage device, for example.

<< Calculation Processing Unit 131 >>
The arithmetic processing unit 131 includes a determination unit 131a, a comparison and identification unit 131b, an amplification unit 131c, and a ground fault location unit 131d.

  The determination unit 131a has a function of determining whether or not the ground fault current detected by the first and second current detection devices 110 and 120 is equal to or greater than a predetermined current value. When the detected ground fault current is equal to or greater than a predetermined current value, the detected ground fault current is larger than the ground fault current indicating the largest current value (hereinafter referred to as “first ground fault current”). The process is shifted to specify a change point to be described later with reference to a small ground fault current (hereinafter referred to as “second ground fault current”). On the other hand, when the ground fault current is less than the predetermined current value, the changing point is based on all the current detection devices (in this embodiment, the first and second current detection devices 110 and 120) that detect the ground fault current. In order to identify

  The comparison specifying unit 131b has a function of comparing the respective ground fault currents detected by the first and second current detection devices 110 and 120. Furthermore, the comparison specifying unit 131b specifies the current detection device that has detected the second ground fault current.

  The amplifying unit 131c has a function of amplifying the gain of the ground fault current waveform corresponding to the ground fault current detected by the first and second current detection devices 110 and 120. Thereby, the change point of the ground fault current waveform mentioned later can be clarified. Further, the amplifying unit 131c has a function of calculating the amplification degree at which the rising (falling) angle of the ground fault current waveform is the largest. The amplification degree refers to the degree to which the gain of the ground fault current waveform detected by the specified current detection device is amplified.

  The ground fault location unit 131d has a function of specifying a change point indicating the time when the ground fault current is generated based on the ground fault current waveform in which the gain is amplified. Furthermore, the ground fault location unit 131d has a function of locating the ground fault point P where the ground fault current is generated in the power system based on the change point.

  The ground fault point locating device 130 having such an arithmetic processing unit 131 can detect the weak ground fault current detected by the first and second current detection devices 110 and 120 that can detect the ground fault current in the high frequency region with high accuracy. The ground fault point P can be determined by amplifying and pinpointing the change point accurately. Hereinafter, an orientation procedure for orientation of the ground fault point P will be described in detail.

=== Procedure for ground fault location ===
The ground fault location procedure in the ground fault location system 100 will be described as follows with reference to FIGS. FIG. 7 is a diagram showing an operation flow of the ground fault location system 100 according to the present embodiment. FIG. 8 is a diagram illustrating an example of a ground fault current waveform of the first and second current detection devices 110 and 120 according to the present embodiment. FIG. 9 is a diagram illustrating an example in which the gain of the ground fault current waveform of the second current detection device 120 according to the present embodiment is amplified. FIG. 10 is a diagram illustrating an example of a ground fault current waveform of the first and second current detection devices 110 and 120 according to the present embodiment. FIG. 11 is a diagram illustrating an example in which the gain of the ground fault current waveform of the first and second current detection devices 110 and 120 according to the present embodiment is amplified.

  A ground fault occurs in the power system (S100). The 1st and 2nd electric current detection apparatuses 110 and 120 detect the ground fault current which flows into the distribution line 300, and transmit the information regarding a ground fault current to the ground fault point location apparatus 130 (S101). As described above, the first and second current detection devices 110 and 120 according to the present embodiment can detect the ground fault current with high accuracy even when a long distance is away from the ground fault point P. In this orientation procedure, the procedure for locating the ground fault point P generated between the first current detection device 110 and the second current detection device 120 will be described as an example. The orientation can be similarly performed using an apparatus.

  The determination unit 131a determines whether or not the current value of the ground fault current is greater than or equal to a predetermined current value based on the information on the ground fault current received from the first and second current detection devices 110 and 120 (S102).

  If the ground fault current is equal to or greater than the predetermined current value (S102: YES), the process is shifted to the comparison specifying unit 131b.

  Next, the comparison specifying unit 131b compares the current values of the ground fault currents detected by the first current detection device 110 and the second current detection device 120 (S103). And the comparison specific | specification part 131b specifies the electric current detection apparatus which shows a ground fault current smaller than the largest ground fault current (S104). That is, since the ground fault current in the distribution line 300 indicates a smaller current value on the load side than on the power source side with respect to the ground fault point P, the comparison and identification unit 131b identifies the second current detection device 120 on the load side. To do. The comparison specifying unit 131b shifts the processing to the amplification unit 131c.

  The above-described S102 (: YES) to S104 will be described more specifically. FIG. 8A shows a ground fault current waveform (hereinafter referred to as “first ground fault current waveform”) corresponding to the ground fault current detected by the first current detection device 110. As shown in FIG. 8A, the first ground fault current waveform is formed by superposing the ground fault current on the steady current indicating the current value I0. It can also be seen that the first ground fault current waveform is generated near the time point t1. FIG. 8B shows a ground fault current waveform (hereinafter referred to as “second ground fault current waveform”) corresponding to the ground fault current detected by the second current detection device 120. It can be seen that the second ground fault current waveform occurs near the time point t2. As shown in FIGS. 8A and 8B, each ground fault current indicating the current values I1 and I2 exceeds a predetermined current value Ip. That is, the determination unit 131a determines that the current values I1 and I2 of the ground fault current detected by the first and second ground fault current detection devices exceed the predetermined current value Ip. Then, the comparison specifying unit 131b specifies that the second ground fault current indicating the current value I2 is smaller than the first ground fault current indicating the current value I1. Therefore, in this orientation procedure, the following description will be continued assuming that the second current detection device 120 is specified.

  Next, the amplifying unit 131c calculates an amplification factor for amplifying the gain of the second ground fault current waveform detected by the identified second current detection device 120 (S105). The amplification degree is a degree to which the gain of the second ground fault current waveform is amplified to such an extent that a change point described later can be specified. The amplifying unit 131c amplifies the gain of the second ground fault current waveform with the calculated amplification degree (S106).

  The above-described S105 and S106 will be described more specifically. FIG. 9 shows a ground fault current waveform obtained by amplifying the gain of the second ground fault current waveform (hereinafter referred to as “second amplified ground fault current waveform”). Amplifying the gain of the second ground fault current waveform means amplifying the amplitude of the second ground fault current waveform. Thereby, the falling angle B in the second amplified ground fault current waveform becomes sharper than the falling angle A before amplification.

  On the other hand, when the ground fault current is less than the predetermined current value (S102: NO), the process is transferred to the amplifying unit 131c.

  The above-described S102 (: NO) will be described more specifically. FIG. 10A shows a first ground fault current waveform, and FIG. 10B shows a second ground fault current waveform. It can be seen that the respective ground fault currents detected by the first and second current detection devices 110 and 120 and indicating the current values I3 and I4 do not exceed the predetermined current value Ip. That is, the determination unit 131a determines that the current values I3 and I4 of the ground fault current detected by the first and second ground fault current detection devices do not exceed the predetermined current value Ip.

  Next, the amplifying unit 131c calculates the gain of the first ground fault current waveform and the second ground fault current waveform corresponding to the ground fault current detected by each of the first current detection device 110 and the second current detection device 120. Amplification is performed at a predetermined amplification within the range of the performance of the amplifying unit 131c (S107). Thereby, it becomes easy to specify the change point mentioned later.

  Next, as shown in FIG. 11A, the ground fault location unit 131d specifies the detection time t3 of the ground fault current in the first amplified ground fault current waveform obtained by amplifying the gain of the first ground fault current waveform. As shown in FIG. 11B, the detection time t4 of the ground fault current in the second amplified ground fault current waveform obtained by amplifying the gain of the second ground fault current waveform is specified (S108). The detection time t3 and the detection time t4 are referred to as change points. Thereby, the ground fault point location unit 131d can determine the ground fault point P (S109).

  In addition, said embodiment is for making an understanding of this invention easy, and is not for limiting and interpreting this invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

=== Summary ===
As described above, the ground fault locating system 100 according to the present embodiment has the magnetic flux density of the magnetic flux generated when the ground fault current flows through the power line of the power system, and the change in permeability corresponding to the change in the magnetic flux density. In order to detect a ground fault current in the cores 111a, 121a formed in an annular shape and the cores 111a, 121a through which the distribution line 300 passes so as to be equal to or less than a predetermined magnetic flux density value determined based on the degree of A plurality of sensors 111, 121 having coils 111b, 121b to be rotated, and a ground fault current detected by each of the plurality of sensors 111, 121, than the first ground fault current indicating the largest current value. The comparison specifying unit 131b that specifies the second ground fault current indicating a small current value, and the amplification unit 131 that amplifies the ground fault current waveform corresponding to the second ground fault current specified by the comparison specifying unit 131b. In the ground fault current waveform amplified by the amplifying unit 131c, the change point indicating the generation time of the second ground fault current is specified, and the ground indicating the point where the ground fault current in the power system is generated based on the change point. A ground fault point location unit 131d for standardizing the entanglement point P; According to the present embodiment, it is possible to detect even a small ground fault current using the sensors 111 and 121 that can detect a ground fault current in a high frequency region with high sensitivity, and amplify the gain of the ground fault current waveform. On the other hand, the change point can be accurately identified and the ground fault point P can be determined.

  The ground fault location system 100 according to the present embodiment further includes a determination unit 131a that determines whether or not a plurality of ground fault currents detected by the plurality of sensors 111 and 121 are equal to or greater than a predetermined current value. When the unit 131a determines that the plurality of ground fault currents is less than the predetermined current value, the amplifying unit 131c includes a plurality of ground fault currents corresponding to the plurality of ground fault currents detected by the plurality of sensors 111 and 121. The ground fault location unit 131d amplifies the waveform, specifies a change point indicating the occurrence time of the ground fault current in the first and second amplified ground fault current waveforms amplified by the amplifier 131c, and based on the change point Then, the ground fault point P indicating the point where the ground fault current in the power system is generated is determined. According to the present embodiment, the change point can be accurately identified by amplifying the ground fault current waveform, and the ground fault point P can be determined.

  Further, the ground fault location unit 131d of the ground fault location system 100 according to the present embodiment calculates the time when the ground fault current occurs at the ground fault point P by calculating backward from the change point. . According to the present embodiment, the ground fault point P can be accurately determined based on the accurately identified change point.

  Further, the predetermined magnetic flux density value in the ground fault location system 100 according to the present embodiment is based on the degree of coincidence between the increase rate of the magnetic flux density and the increase rate of the magnetic permeability when the ground fault current flows through the distribution line 300. Determined. According to the present embodiment, since the change in the relative permeability μr is stable with respect to the change in the magnetic flux density B, variations in the sensors 111 and 121 in each phase can be reduced.

  The cores 111a and 121a of the ground fault location system 100 according to the present embodiment are configured to have a cross-sectional area and a length such that the magnetic flux density is equal to or less than the predetermined magnetic flux density value. According to this embodiment, the enlargement of the sensors 111 and 121 can be suppressed.

  In addition, the sensors 111 and 121 of the ground fault location system 100 according to the present embodiment are determined such that the number of turns of the coils 111b and 121b is equal to or less than a predetermined number. According to the present embodiment, even a weak ground fault current can be detected by an increase in the level of the secondary current. Therefore, the range in which the sensors 111 and 121 can detect the ground fault current is set. Can be spread.

  The power system to which the ground fault location system 100 according to the present embodiment is applied is a 22 kV special high-voltage distribution system. According to this embodiment, since a sensor having high frequency characteristics is used, the ground fault point P can be accurately determined even in a 22 kV special high voltage distribution system to which a resistance grounding method or a non-grounding method is generally applied.

  The time in the ground fault location system 100 according to the present embodiment is specified based on time information transmitted from the GPS. According to the present embodiment, the ground fault point P can be accurately determined based on an accurate time.

DESCRIPTION OF SYMBOLS 10 Ground fault location system 111, 121 Sensor 111a, 121a Winding core 111b, 121b Coil 131a Determination part 131b Comparison specific part 131c Amplification part 131d Ground fault point location part

Claims (10)

An annularly formed core in which the magnetic flux density of the magnetic flux generated when a ground fault current flows through the power line of the power system is equal to or less than a predetermined magnetic flux density value, and the ground fault in the core through which the power line penetrates A plurality of sensors having coils wound to detect current;
Among the ground fault currents detected by each of the plurality of sensors, a comparison specifying unit that specifies a second ground fault current indicating a current value smaller than the first ground fault current indicating the largest current value;
An amplifying unit for amplifying a ground fault current waveform corresponding to the second ground fault current specified by the comparison specifying unit;
In the ground fault current waveform amplified by the amplifying unit, the change point indicating the generation time of the second ground fault current is specified, and the ground fault current in the power system is generated based on the change point. A ground fault location unit that locates a ground fault point indicating
A ground fault location system characterized by comprising: A determination unit for determining whether or not the plurality of ground fault currents detected by the plurality of sensors are equal to or greater than a predetermined current value;
When the determination unit determines that the plurality of ground fault currents is less than the predetermined current value,
The amplifying unit amplifies a plurality of ground fault current waveforms corresponding to the plurality of ground fault currents detected by the plurality of sensors,
The ground fault location unit identifies a change point that represents the occurrence time of the ground fault current in the plurality of ground fault current waveforms amplified by the amplifier, and based on the change point, the power grid The ground fault point locating system according to claim 1 or 2, wherein a ground fault point indicating a point where a ground fault current is generated is determined. The ground fault point locating unit is configured to determine the ground fault point by calculating a time when the ground fault current occurs at the ground fault point by calculating backward from the change point. The ground fault location system according to claim 2. The predetermined magnetic flux density value is determined based on a degree of coincidence between an increase rate of the magnetic flux density when the ground fault current flows through the power line and an increase rate of the magnetic permeability corresponding to the magnetic flux density. The ground fault location system as described in any one of Claims 1 thru | or 3 characterized by the above-mentioned. 5. The core according to claim 1, wherein the core has a cross-sectional area and a length such that the magnetic flux density is equal to or less than the predetermined magnetic flux density value. The ground fault location system described. The ground fault point locating system according to any one of claims 1 to 5, wherein the sensor is determined such that the number of turns of the coil is equal to or less than a predetermined number of turns. The ground fault location system according to any one of claims 1 to 6, wherein the power system is a 22 kV special high-voltage distribution system. The ground fault location system according to any one of claims 1 to 7, wherein the time is specified based on time information transmitted from a GPS. An annular shape in which the magnetic flux density of the magnetic flux generated when a ground fault current flows through the power line of the power system is equal to or less than a predetermined magnetic flux density value determined based on the degree of change in permeability corresponding to the change in magnetic flux density. Among the ground fault currents detected by each of a plurality of sensors, the core formed in the coil and the coil wound around the core through which the power line penetrates to detect the ground fault current. A second ground fault current indicating a current value smaller than a first ground fault current indicating a large current value is identified;
Amplifying a ground fault current waveform corresponding to the identified second ground fault current;
In the amplified ground fault current waveform, a change point indicating the generation time of the second ground fault current is specified, and a ground fault indicating a point where the ground fault current is generated in the power system based on the change point A ground fault location method characterized by location of points. In the arithmetic processing unit used for the ground fault location system,
An annular shape in which the magnetic flux density of the magnetic flux generated when a ground fault current flows through the power line of the power system is equal to or less than a predetermined magnetic flux density value determined based on the degree of change in permeability corresponding to the change in magnetic flux density. Among the ground fault currents detected by each of a plurality of sensors, the core formed in the coil and the coil wound around the core through which the power line penetrates to detect the ground fault current. A function of specifying a second ground fault current indicating a smaller current value than the first ground fault current indicating a large current value;
A function of amplifying a ground fault current waveform corresponding to the identified second ground fault current;
In the amplified ground fault current waveform, a change point indicating the generation time of the second ground fault current is specified, and a ground fault indicating a point where the ground fault current is generated in the power system based on the change point The ability to locate points,
A program that executes

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