JP6881044B2 - Ground fault point locating system, ground fault locating method and program - Google Patents

Description

The present invention relates to a ground fault point determination system.

For example, a current detection sensor for detecting a ground fault point when a ground fault occurs in an electric power system is known. (For example, Patent Document 1).

Japanese Unexamined Patent Publication No. 5-268723 Japanese Unexamined Patent Publication No. 2004-132762

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

Further, Patent Document 2 discloses a system for determining a ground fault point by calculating the difference in surge arrival time at each point by detecting the zero-phase current and the zero-phase voltage of the power 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 when a sudden change in the zero-phase voltage is detected. However, the system according to Patent Document 2 works for a ground fault with a large surge current such as a circuit breaker in a substation operates, but it works for a ground fault with a small surge current such that the circuit breaker does not operate. On the other hand, there was a risk that the ground fault point could not be identified.

The main invention for solving the above-mentioned problems is a winding core formed in an annular shape so that 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 lower than a predetermined magnetic flux density value. A plurality of sensors having a coil wound around the winding core through which the power line penetrates to detect the ground fault current, and the largest current value among the ground fault currents detected by each of the plurality of sensors. Amplifies the ground fault current waveform corresponding to the second ground fault current specified by the comparative identification unit and the comparative identification unit that specifies the second ground fault current that indicates a current value smaller than the first ground fault current. In the amplification unit and the ground fault current waveform amplified by the amplification unit, a change point representing the generation time of the second ground fault current is specified, and the ground fault in the power system is based on the change point. It is characterized by including a ground fault point setting unit for defining a ground fault point indicating a point where an electric current is generated.

Other features of the invention will become apparent with reference to the accompanying drawings and the description herein.

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

It is a figure which shows the ground fault point setting 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 current detection which concerns on this embodiment. It is a figure which shows the characteristic of the winding core which concerns on this embodiment. It is a figure which shows the characteristic of the winding core which concerns on this embodiment. It is a figure which shows an example of the structure of the ground fault point setting apparatus which concerns on this embodiment. It is a figure which shows the operation flow of the ground fault point setting 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.

The description of this specification and the accompanying drawings will clarify at least the following matters. In the following description, the parts with the same reference numerals represent the same elements, and their basic configurations and operations are the same.

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

The ground fault point locating system 100 is a system for locating a location (hereinafter, referred to as "ground fault point P") where a ground fault has occurred in an electric power system (22 kV distribution system in this embodiment). As shown in FIG. 1, the ground fault point determination system 100 has 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. It is configured to include a ground fault point locating device 130 for locating. In FIG. 1, for convenience of explanation, two units, a first current detection device 110 and a second current detection device 120, are shown to be provided in the power system, but more than two current detection devices are provided. You may.

== 1st and 2nd 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 showing a sensor box 112 according to the present embodiment. FIG. 3 is a diagram showing a sensor 111 for current detection according to the present embodiment. 4 and 5 are views showing the characteristics of the winding core 111a according to the present embodiment. In the following description, the first current detection device 110 will be described as a representative, but the same applies to the second current detection device 120, and the same applies to the current detection device (not shown).

The first current detection device 110 is a device installed in the power system and measures a physical quantity that fluctuates according to the state of the power of the power system. The first current detection device 110 is composed of, for example, a sensor 111 that measures a physical quantity that fluctuates according to the state of power of the power system including the current or voltage of the distribution line 300, a sensor box 112 that houses the sensor 111, and the sensor 111. It is configured to include a measurement terminal 113 that transmits a measurement result to the ground fault point positioning 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, a frequency, and the like. 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 simplification of the description. Actually, as shown in FIG. 2, a sensor box 112 is provided in each phase of the distribution line 300. Then, each sensor box 112 is attached to the distribution line 300 of each phase, and the sensor 111 housed in each sensor box 112 measures a physical quantity that fluctuates according to the state of the electric power of the power system.

The measuring 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 point locating device 130 via the communication path 200.

The measuring terminal 113 uses the physical quantity values of each phase of the distribution line 300 measured by the sensor 111 to calculate the values of other physical quantities that fluctuate according to the power state of the power system, and determines the ground fault point. It can also be transmitted to the device 130.

For example, the measuring terminal 113 acquires the current value of each phase of the distribution line 300, calculates the zero-phase current by synthesizing the acquired current value, and transmits it to the ground fault point locating device 130. Alternatively, the measuring terminal 113 acquires the voltage value of each phase of the distribution line 300, calculates the zero-phase voltage by synthesizing the acquired voltage value, and transmits it to the ground fault point locating device 130. May be.

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 the time information can be obtained. It is associated and transmitted to the ground fault point locating device 130. In the following, the zero-phase current may be described as a ground fault current.

By the way, since the power system according to the present embodiment is a 22 kV distribution system, a resistance grounding method or a non-grounding method is adopted as the grounding method of the transformer (not shown) provided in the substation (not shown). The resistance grounding method is a method in which the neutral point of the transformer and the ground are connected by a conductor via a resistor to be grounded, and the non-grounding method is a method in which the neutral point grounding is not performed.

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

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

As shown in FIG. 3, the sensor 111 is wound to detect an annular winding core 111a 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 has a ground fault. It is configured to have a coil 111b wound around a core 111a. When a ground fault current flows through the distribution line 300, the sensor 111 changes the magnetic flux Φ of the winding core 111a, 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 winding 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 winding 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 the ground fault current regardless of whether the grounding method of the transformer of the 22kV distribution system is the resistance grounding method or the non-grounding method.

That is, by reducing the magnetic flux density B of the magnetic flux generated in the winding core 111a so as 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 sensor 111 mounted on the distribution line 300 of each phase. This makes it possible to measure the ground fault current over a wide band. Hereinafter, the winding core 111a will be described in more detail with reference to FIGS. 4 and 5.

FIG. 4 shows the relationship between the relative magnetic permeability μr of the winding core 111a and the magnetic flux density B of the magnetic flux generated in the winding core 111a. The characteristic curve when the winding core 111a is a permalloy core is illustrated, and it can be seen that the value of the relative magnetic permeability μr differs greatly depending on the magnetic flux density B. Therefore, in order to suppress variations in the characteristics of the sensor 111 of each phase, it is necessary to generate a magnetic flux density B in the winding core 111a in a range in which the fluctuation of the relative magnetic permeability μr is as small as possible.

With reference to FIG. 4, it can be seen that the smaller the magnetic flux density B, the smaller the fluctuation of the relative permeability μr. Therefore, the relationship between the magnetic flux density B and the relative magnetic permeability μr when the magnetic flux density B is 3000 gauss or less is expanded and shown in FIG. There is a linear relationship between the change in relative permeability μr and the change in magnetic flux density B, that is, the rate of increase in magnetic flux density B and the rate of increase in specific magnetic flux density μr when a ground fault current flows through the distribution line 300. For example, the change in relative magnetic permeability μr is stable with respect to the change in magnetic flux density B. The range of the magnetic flux density B at which the relative magnetic permeability μr is stable is a region in which there is little variation in the sensors 111 of each phase.

Further, referring to FIG. 5, it can be seen that the range in which the relative magnetic permeability μr linearly increases as the magnetic flux density B increases is the range in which the magnetic flux density B is equal to or less than a predetermined value. In the case shown in FIG. 5, the range in which 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 the respective increase rates or change rates may be within a predetermined range.

As described above, the magnetic flux density B of the magnetic flux generated in the winding core 111a when the ground fault current flows through the distribution wire 300 is a predetermined magnetic flux density determined based on the degree of change in the relative permeability μr with respect to the change in the magnetic flux density B. By setting the value to less than or equal to the value, the range of current that can be detected by the sensor 111 can be expanded, regardless of whether the grounding method of the transformer of the 22kV distribution system is the resistance grounding method or the non-grounding method. It becomes possible to detect the ground fault current.

Further, in this way, the material used for the winding core 111a is determined by determining the above-mentioned 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 magnetic permeability μr with respect to the change in the magnetic flux density B. It is possible to determine the upper limit value of the magnetic flux density B 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 winding 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 winding core 111a. Therefore, the winding core 111a has a cross-sectional area S and a length L of a predetermined value or more so that the magnetic flux density B of the magnetic flux generated in the winding core 111a when a ground fault current is generated is suppressed to a predetermined magnetic flux density value or less. Must be configured to be. On the other hand, since there is a certain limit to the increase in size of the winding core 111a, the winding 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 is equal to or more than a certain lower limit value. It will be configured to have S and length L.

Further, the current flowing through the coil 111b when the distribution line 300 has a ground fault is inversely proportional to the number of turns of the coil 111b. Therefore, the sensor 111 according to the present embodiment is defined so 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 level of the secondary current, so that the range in which the ground fault current can be detected can be detected. Can be expanded.

For example, when detecting a ground fault in a non-grounded power system, the distribution lines of each phase do not need to be passed through the distribution lines 300 for three phases in one winding core 111a. Sensors 111 are provided in each of the 300s, and each can detect a ground fault current of about several tens of mA.

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

== Ground fault point locator 130 ==
The ground fault point locating device 130 will be described as follows with reference to FIG. FIG. 6 is a diagram showing an example of the configuration of the ground fault point locating device 130 according to the present embodiment.

The ground fault point locator 130 detects the ground fault current generated when a ground fault occurs with the above-mentioned first and second current detection devices 110 and 120, and amplifies the ground fault current to ground the ground. It is a device that specifies the detection time of the entanglement current and defines the ground fault point P.

The ground fault current generated by the ground fault of the distribution line 300 is attenuated as the propagating distance increases. 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 point locating device 130 detects a small ground fault current by being attenuated by using the first and second current detection devices 110 and 120 described above, and the ground fault current waveform corresponding to the ground fault current. And amplify the gain of the ground fault current waveform. Based on the amplified ground fault current waveform, a change point indicating the occurrence time of the ground fault current is specified, and the ground fault point P is defined based on the change point.

As shown in FIG. 6, the ground fault point locating 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. It is configured to include, and each is connected so that it can communicate.

The arithmetic processing unit 131 is composed of, for example, a CPU or an MPU. The arithmetic processing unit 131 realizes various functions by issuing 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 in detail later. The main storage unit 132 is composed of, for example, a volatile memory such as a RAM. 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 information to the communication network. The auxiliary storage unit 135 is a device that stores a program for processing by the arithmetic processing unit 131. The auxiliary storage unit 135 is composed of, for example, a non-volatile memory such as a hard disk drive, an SSD, or an optical storage device.

<< Arithmetic processing unit 131 >>
The arithmetic processing unit 131 includes a determination unit 131a, a comparison identification unit 131b, an amplification unit 131c, and a ground fault point setting 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 higher than a predetermined current value. When the detected ground fault current is equal to or higher than a predetermined current value, it is larger than the ground fault current (hereinafter, referred to as "first ground fault current") indicating the largest current value among the detected ground fault currents. The process is shifted in order to identify the change point 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 a predetermined current value, the change point is based on all the current detection devices (first and second current detection devices 110 and 120 in this embodiment) that have detected the ground fault current. Migrate processing to identify.

The comparison identification unit 131b has a function of comparing the ground fault currents detected by the first and second current detection devices 110 and 120, respectively. Further, the comparative identification unit 131b identifies the current detection device that has detected the second ground fault current.

The amplification 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. As a result, the change point of the ground fault current waveform, which will be described later, can be clarified. Further, the amplification 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 degree of amplification refers to the degree of amplifying the gain of the ground fault current waveform detected by the specified current detection device.

The ground fault point setting unit 131d has a function of specifying a change point indicating the time when the ground fault current occurs based on the ground fault current waveform in which the gain is amplified. Further, the ground fault point locating unit 131d has a function of locating the ground fault point P in which 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 detects a weak ground fault current detected by the first and second current detection devices 110 and 120 capable of detecting the ground fault current in the high frequency region with high accuracy. The ground fault point P can be defined by amplifying and accurately identifying the change point. Hereinafter, the locating procedure for locating the ground fault point P will be described in detail.

=== Ground fault setting procedure ===
The procedure for locating the ground fault point in the ground fault point locating system 100 will be described as follows with reference to FIGS. 7 to 11. FIG. 7 is a diagram showing an operation flow of the ground fault point determination system 100 according to the present embodiment. FIG. 8 is a diagram showing an example of ground fault current waveforms of the first and second current detection devices 110 and 120 according to the present embodiment. FIG. 9 is a diagram showing 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 showing an example of ground fault current waveforms of the first and second current detection devices 110 and 120 according to the present embodiment. FIG. 11 is a diagram showing an example in which the gain of the ground fault current waveforms 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 first and second current detection devices 110 and 120 detect the ground fault current flowing through the distribution line 300 and transmit information on the ground fault current to the ground fault point locating device 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 if they are separated from the ground fault point P by a long distance. In this localization procedure, as an example, a procedure for defining a ground fault point P generated between the first current detection device 110 and the second current detection device 120 will be described, but it goes without saying that three or more current detection devices are detected. The same can be done by using the device.

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

When the ground fault current is equal to or higher than a predetermined current value (S102: YES), the process is shifted to the comparative identification unit 131b.

Next, the comparison identification 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). Then, the comparative identification unit 131b identifies a current detection device that 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 shows a smaller current value on the load side than on the power supply side with reference to the ground fault point P, the comparison identification unit 131b specifies the second current detection device 120 on the load side. To do. The comparative identification unit 131b shifts the process to the amplification unit 131c.

The above-mentioned 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 superimposing the ground fault current on the steady current indicating the current value I0. Further, it can 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 is generated near the time point t2. Then, as shown in FIGS. 8A and 8B, the ground fault currents showing the current values I1 and I2 each exceed 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 a predetermined current value Ip. Then, the comparative identification unit 131b identifies that the second ground fault current showing the current value I2 is smaller than the first ground fault current showing the current value I1. Therefore, in this localization procedure, the second current detection device 120 will be specified, and the following description will be continued.

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

The above-mentioned S105 and S106 will be described more specifically. FIG. 9 shows a ground fault current waveform in which the gain of the second ground fault current waveform is amplified (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. As a result, the fall angle B in the second amplified ground fault current waveform becomes sharper than the fall angle A before amplification.

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

The above-mentioned 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 ground fault currents detected by the first and second current detectors 110 and 120 and showing the current values I3 and I4 do not exceed the predetermined current values 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 values Ip.

Next, the amplification unit 131c obtains the gains of the first ground fault current waveform and the second ground fault current waveform corresponding to the ground fault currents detected by the first current detection device 110 and the second current detection device 120, respectively. Amplification is performed at a predetermined amplification degree within the range of the performance of the amplification unit 131c (S107). This makes it easier to identify the change points described later.

Next, as shown in FIG. 11A, the ground fault point locating unit 131d specifies the detection time t3 of the ground fault current in the first amplified ground fault current waveform in which the gain of the first ground fault current waveform is amplified. 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. As a result, the ground fault point setting unit 131d can determine the ground fault point P (S109).

It should be noted that the above embodiment is for facilitating the understanding of the present invention, and is not for limiting and interpreting the present invention. The present invention can be modified and improved without departing from the spirit thereof, and the present invention also includes an equivalent thereof.

=== Summary ===
As described above, in the ground fault point determination system 100 according to the present embodiment, the magnetic flux density of the magnetic flux generated when the ground fault current flows through the power line of the power system is the change in the magnetic permeability corresponding to the change in the magnetic flux density. The winding cores 111a and 121a formed in an annular shape and the winding cores 111a and 121a through which the distribution wire 300 penetrates are wound to detect a ground fault current so as to be equal to or less than a predetermined magnetic flux density value determined based on the degree of Of the ground fault currents detected by the plurality of sensors 111, 121 having the rotated coils 111b, 121b, and the plurality of sensors 111, 121, respectively, the first ground fault current showing the largest current value. A comparative identification unit 131b that specifies a second ground fault current showing a small current value, an amplification unit 131c that amplifies the ground fault current waveform corresponding to the second ground fault current specified by the comparison specific unit 131b, and an amplification unit 131c. In the ground fault current waveform amplified by, the change point representing the occurrence time of the second ground fault current is specified, and the ground fault point P indicating the point where the ground fault current occurs in the power system is defined based on the change point. It is provided with a ground fault point setting unit 131d. According to this embodiment, even a minute ground fault current can be detected by using the sensors 111 and 121 capable of detecting the ground fault current in the high frequency region with high sensitivity, and the gain of the ground fault current waveform is amplified. At the same time, the change point can be accurately identified and the ground fault point P can be defined.

Further, the ground fault point determination system 100 according to the present embodiment further includes a determination unit 131a for determining whether or not the plurality of ground fault currents detected by the plurality of sensors 111 and 121 are equal to or higher than a predetermined current value. When the unit 131a determines that the plurality of ground fault currents is less than a predetermined current value, the amplification unit 131c has a plurality of ground fault currents corresponding to the plurality of ground fault currents detected by the plurality of sensors 111 and 121. The waveform is amplified, and the ground fault point locating unit 131d identifies a change point representing the generation time of the ground fault current in the first and second amplified ground fault current waveforms amplified by the amplification unit 131c, and is based on the change point. , The ground fault point P indicating the point where the ground fault current is generated in the power system is defined. According to this embodiment, the change point can be accurately specified and the ground fault point P can be defined by amplifying the ground fault current waveform.

Further, the ground fault point locating unit 131d of the ground fault point locating system 100 according to the present embodiment calculates the time when the ground fault current is generated at the ground fault point P by calculating back from the change point, thereby calculating the ground fault point P. To position. According to the present embodiment, the ground fault point P can be accurately located based on the accurately identified change point.

Further, the predetermined magnetic flux density value in the ground fault point positioning 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. Is determined. According to this embodiment, since the change in the relative magnetic permeability μr is stable with respect to the change in the magnetic flux density B, the variation in the sensors 111 and 121 of each phase can be reduced.

Further, the winding cores 111a and 121a of the ground fault point positioning 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, it is possible to suppress the increase in size of the sensors 111 and 121.

Further, the sensors 111 and 121 of the ground fault point determination system 100 according to the present embodiment are defined so that the number of turns of the coils 111b and 121b is equal to or less than a predetermined number of turns. According to this embodiment, even a weak ground fault current can be detected by increasing the level of the secondary current. Therefore, the range in which the ground fault current can be detected in the sensors 111 and 121 is set. Can be expanded.

The power system to which the ground fault point positioning 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 defined even in a 22 kV special high voltage distribution system to which a resistance grounding method or a non-grounding method is generally applied.

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

10 Ground fault point locating system 111, 121 Sensor 111a, 121a Winding core 111b, 121b Coil 131a Judgment unit 131b Comparison specific unit 131c Amplification unit 131d Ground fault point locating unit

Claims (9)

The ground fault is formed between a winding core formed in an annular shape so that 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 winding core through which the power line penetrates. Multiple sensors with a coil that is wound to detect current, and
Among the ground fault currents detected by each of the plurality of sensors, a comparative identification unit that specifies a second ground fault current that indicates a current value smaller than the first ground fault current that indicates the largest current value, and a comparative identification unit.
An amplification unit that amplifies the ground fault current waveform corresponding to the second ground fault current specified by the comparison specific unit, and an amplification unit.
In the ground fault current waveform amplified by the amplification unit, a change point representing the occurrence time of the second ground fault current is specified, and a point at which the ground fault current is generated in the power system based on the change point. The ground fault setting part that defines the ground fault point indicating
A ground fault locating system characterized by being equipped with. The ground絡点orientation section, by calculating the time at which the ground fault current in the ground絡点by back calculation from the change point has occurred in claim 1, characterized by locating the land絡点The described ground fault point positioning system. The predetermined magnetic flux density value is determined based on the degree of coincidence between the increase rate of the magnetic flux density when the ground fault current flows through the power line and the increase rate of the magnetic permeability corresponding to the magnetic flux density. The ground fault locating system according to claim 1 or 2, which is characterized. The winding 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, according to any one of claims 1 to 3. The described ground fault point positioning system. The ground fault point determination system according to any one of claims 1 to 4 , wherein the sensor is defined so that the number of turns of the coil is equal to or less than a predetermined number of turns. The ground fault locating system according to any one of claims 1 to 5 , wherein the power system is a 22 kV special high-voltage power distribution system. The ground fault locating system according to any one of claims 1 to 6 , wherein the time is specified based on time information transmitted from GPS. An annular structure 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 the magnetic permeability corresponding to the change in the magnetic flux density. Of the ground fault currents detected by each of the plurality of sensors having the winding core formed in the above and the coil wound around the winding core through which the power line penetrates to detect the ground fault current. Identify the second ground fault current that shows a smaller current value than the first ground fault current that shows a larger current value.
Amplify the ground fault current waveform corresponding to the specified second ground fault current,
In the amplified ground fault current waveform, a change point representing the occurrence time of the second ground fault current is specified, and based on the change point, a ground fault indicating the point where the ground fault current is generated in the power system. A ground fault point locating method characterized by locating a point. For the arithmetic processing unit used in the ground fault point determination system,
An annular structure 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 the magnetic permeability corresponding to the change in the magnetic flux density. Of the ground fault currents detected by each of the plurality of sensors having the winding core formed in the above and the coil wound around the winding core through which the power line penetrates to detect the ground fault current. A function to identify the second ground fault current that shows a current value smaller than the first ground fault current that shows a large current value, and
A function to amplify the ground fault current waveform corresponding to the specified second ground fault current, and
In the amplified ground fault current waveform, a change point representing the occurrence time of the second ground fault current is specified, and based on the change point, a ground fault indicating the point where the ground fault current is generated in the power system. The function to set points and
A program that executes.

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