JP6303240B2 - Detection device, power supply system, and detection method - Google Patents

Description

  The present invention relates to a detection device, a power supply system, and a detection method.

In substations, power is supplied by using transformers and lightning arresters. Of these, the frequency of failure of the lightning arrester is low, but since the degree of inhibition in the event of failure is very large, a new method of managing the deterioration of the lightning arrester is required.
In general, the characteristics of the lightning arrester include one or more of (1) insulation resistance, (2) operation start voltage (for example, applied voltage value when leakage current is 1 mA), and (3) resistance leakage current measurement. Manage with measurement methods. Here, (1) and (2) are mainly applied to lightning arresters for DC 1500V railway and high-voltage distribution lines, and (3) is mainly applied to lightning arresters for extra high voltage.
By the way, the total leakage current in a lightning arrester during operation of the equipment is often a weak current of 0.5 to 1.0 mA or less in the first place, and the resistance current contained therein, that is, the deterioration of the lightning arrester. Thus, the current component generated is not easy to measure directly. In response to such a problem, various methods for calculating the resistance leakage current from the total leakage current measurement value during operation of the equipment have been proposed (see, for example, Patent Document 1).

JP 2000-321318 A

  However, since the leakage current that is a sign of failure is weak, the harmonic component (noise) superimposed on the power system itself of the power supply system and the current component (capacitance component) that flows due to the parasitic capacitance added to the lightning arrester When the current is large, it is difficult to detect with high accuracy.

  In view of the problems as described above, an object of the present invention is to provide a detection device, a power supply system, and a detection method that can accurately detect deterioration of a lightning arrester.

One aspect of the present invention is a detection device that detects a leakage current flowing through a nonlinear resistance element, the magnitude of the total leakage current including the leakage current flowing through the nonlinear resistance element, and each frequency component included in the total leakage current. A current detection sensor capable of outputting a detection signal having an intensity proportional to both, a frequency component acquisition unit for acquiring the intensity for each harmonic component of the detection signal, and the acquired intensity for each harmonic component A leakage current determination unit that determines whether or not a leakage current is flowing through the nonlinear resistance element , wherein the leakage current determination unit includes a plurality of the predetermined number or more of the intensities for each of the harmonic components. The detection device determines that the leakage current is flowing when the intensity of the harmonic component exceeds a predetermined determination threshold .

  In addition, according to one aspect of the present invention, in the above-described detection device, the leakage current determination unit is configured such that the intensity of a plurality of harmonic components that are a predetermined number or more consecutive out of odd-order harmonic components exceeds the determination threshold. If it is determined that the leakage current is flowing.

  In one embodiment of the present invention, in the above-described detection device, the leakage current determination unit sets the determination threshold as the intensity of a fundamental wave component of the detection signal.

  One embodiment of the present invention is the above-described detection device, wherein the current detection sensor is a coil attached so as to surround a ground wire through which the total leakage current flows, and the frequency component acquisition unit includes the coil. Intensity for each harmonic component of the detection signal, which is a voltage excited by the.

  Another embodiment of the present invention is a power supply system including the above-described detection device, a lightning arrester including the nonlinear resistance element, and an overhead wire to which an AC voltage is applied.

One embodiment of the present invention is a detection method for detecting a leakage current flowing through a nonlinear resistance element, the magnitude of the total leakage current including the leakage current flowing through the nonlinear resistance element, and the frequency of the total leakage current. A step of outputting a detection signal having an intensity proportional to both, a step of acquiring an intensity for each harmonic component of the detection signal, and the nonlinear resistance based on the acquired intensity for each harmonic component possess determining whether current is flowing leaking the device, and determining whether the leakage current is flowing is further less than a predetermined number of intensity for each of the harmonic components It is a detection method including the step of determining that the leakage current is flowing when the intensity of the plurality of harmonic components exceeds a predetermined determination threshold .

  According to the above-described detection device, power supply system, and detection method, it is possible to accurately detect the deterioration of the lightning arrester.

It is a figure showing the whole electric power supply system composition concerning a 1st embodiment. It is a figure explaining the leakage current which arises in the lightning arrester which concerns on 1st Embodiment. It is a figure which shows the intensity | strength for every frequency component of the leakage current which arises in the lightning arrester which concerns on 1st Embodiment. It is a figure explaining the influence of the parasitic capacitance in the lightning arrester which concerns on 1st Embodiment. It is a figure explaining the function of the current detection sensor concerning a 1st embodiment. It is a figure explaining the function of the leakage current determination part which concerns on 1st Embodiment. It is a figure explaining the function of the leakage current determination part which concerns on the modification of 1st Embodiment. It is a figure which shows the example of installation of the detection apparatus which concerns on 1st Embodiment.

<First Embodiment>
Hereinafter, the power transmission system and the detection apparatus according to the first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram illustrating an overall configuration of a power supply system according to the first embodiment.
A power transmission system 1 shown in FIG. 1 is a facility that supplies power to a railway vehicle that travels along a route. As shown in FIG. 1, the power transmission system 1 includes an overhead line 10, a lightning arrester 20, and a detection device 30.
The overhead wire 10 is applied with an AC voltage (hereinafter also referred to as overhead wire voltage) by a substation (not shown) separately installed. The overhead wire 10 supplies electric power by applying the AC voltage to the railway vehicle. In the present embodiment, the overhead wire 10 is applied with a relatively high AC voltage having an effective value of, for example, about 30,000 volts. The frequency of the AC voltage is, for example, 60 Hz (or 50 Hz).
The lightning arrester 20 is electrically connected between the overhead wire 10 and the ground point G. The lightning arrester 20 includes a nonlinear resistance element 200 (described later) having nonlinear characteristics. Thereby, the lightning arrester 20 maintains an insulation state with respect to the alternating voltage applied to the overhead wire 10 from the substation, and on the other hand, it is in a low resistance (short circuit) state against a high surge voltage caused by a lightning strike or the like. The electric charge is discharged to the ground point G (ground). Thereby, the lightning arrester 20 prevents damage and failure of equipment due to lightning strikes and the like.
The detection device 30 is a device used for evaluating the soundness of the lightning arrester 20. When the insulation characteristics of the lightning arrester 20 (nonlinear resistance element 200) deteriorate, a current starts to flow through the nonlinear resistance element 200 by a normal overhead line voltage, and finally the overhead line 10 and the ground point G are short-circuited. If it does so, malfunction may arise in the whole electric power system, such as damage of an apparatus by electric leakage. The detection device 30 detects the leakage current (total leakage current Io) flowing from the overhead wire 10 to the ground point G through the lightning arrester 20, and analyzes this to determine whether the soundness (insulation characteristics) of the lightning arrester 20 has deteriorated. ) In advance.

  As shown in FIG. 1, the lightning arrester 20 includes a nonlinear resistance element 200 therein. In the present embodiment, the non-linear resistance element 200 is a resistance element made of zinc oxide and has a non-linear characteristic in which current flows only when a voltage equal to or higher than a predetermined voltage threshold is applied. The non-linear resistance element 200 is usually housed and protected in an insulator or the like. Due to such a structure, the lightning arrester 20 is electrically added with a parasitic capacitance 201 (also referred to as stray capacitance). In the electric circuit, the parasitic capacitance 201 can be regarded as being connected in parallel to the nonlinear resistance element 200 (see FIG. 1).

  Assuming that the current component flowing through the non-linear resistance element 200 is the resistance component current Ir and the current component flowing through the parasitic capacitance 201 is the capacitance component current Ic, the current flowing through the ground line g (total leakage current Io) is the resistance component current Ir. This is a current (Io = Ir + Ic) obtained by synthesizing the vector of the electrostatic capacity divided current Ic. In other words, the total leakage current Io is always observed as the capacitance current Ic superimposed on the resistance current Ir. Here, to determine whether or not the nonlinear resistance element 200 has deteriorated, it is necessary to analyze the resistance current Ir. However, since the parasitic capacitance 201 exists, it is difficult to directly measure this. Therefore, in order to evaluate the soundness of the non-linear resistance element 200 based on the resistance component current Ir, it is necessary to judge only the component of the resistance component current Ir from the observed total leakage current Io.

The detection device 30 includes a current detection sensor 300 and a main body 310.
In the present embodiment, the current detection sensor 300 is a current detection coil attached so as to surround the ground wire g connecting the lightning arrester 20 and the ground point G. The current detection sensor 300, which is a coil, outputs an induced voltage that is excited according to a current (total leakage current Io) flowing through the ground line g as a detection signal. In the present embodiment, the current detection sensor 300 is configured by, for example, a Rogowski coil that is not easily affected by disturbance and can accurately detect a current flowing through the ground wire g.

The main body 310 according to the present embodiment is a general-purpose computer having a CPU (Central Processing Unit) inside. The CPU included in the main body unit 310 functions as the frequency component acquisition unit 311 and the leakage current determination unit 312 by reading a dedicated program.
The frequency component acquisition unit 311 performs a Fourier transform process on the detection signal input through the current detection sensor 300, and acquires the intensity of each fundamental wave component and harmonic component of the detection signal.
The leakage current determination unit 312 determines whether or not the leakage current is flowing through the nonlinear resistance element 200 based on the intensity for each harmonic component acquired by the frequency component acquisition unit 311 and a predetermined determination threshold. judge.

FIG. 2 is a diagram for explaining a leakage current generated in the lightning arrester according to the first embodiment.
In the graph shown in FIG. 2, the supply voltage [V] and the resistance flowing through the non-linear resistance element 200 are plotted on a horizontal axis with a period corresponding to one cycle of the supply voltage applied to the lightning arrester 20 (AC voltage applied to the overhead wire 10). The divided current Ir [A] is represented on the vertical axis. In the graph shown in FIG. 2, a lightning arrester for a low-voltage circuit is used as an example of study of the proposed method.

  Here, when the insulation characteristics of the non-linear resistance element 200 are not deteriorated, no current should flow through the non-linear resistance element 200 even when a supply voltage of about ± 100 V is applied (the resistance current Ir is always zero). . However, in the nonlinear resistance element 200, when the deterioration of the insulation characteristics proceeds, the voltage threshold value at which the insulation state is maintained decreases. Then, as shown in FIG. 2, a pulsed leakage current flows at the timing when the salary voltage reaches its peak. Such a leakage current occurs when the supply voltage instantaneously exceeds the threshold voltage value of the non-linear resistance element 200 at the peak supply voltage. In the example shown in FIG. 2, the resistive current Ir has a pulse wave having a time width corresponding to 1/5 to 1/7 of the cycle every half cycle of the supply voltage.

FIG. 3 is a diagram illustrating the intensity for each frequency component of the leakage current generated in the lightning arrester according to the first embodiment.
The graph shown in FIG. 3 shows the intensity (Fourier coefficient) for each frequency component (the order of the fundamental wave and the harmonic) of the resistive current Ir shown in FIG. Here, the resistance current Ir shown in FIG. 2 is regarded as a waveform in which sine waveforms alternately protrude in the positive and negative directions in a period corresponding to 1/6 period for each half cycle of the supply voltage. Then, as shown in FIG. 3, it can be seen that the resistance component current Ir is distributed with a relatively high intensity in the third to fifteenth harmonic components. Specifically, the resistance current Ir (FIG. 2) has a tendency that harmonics from the third order to the fifth order have almost the same intensity as the fundamental wave, and gradually decrease as the order becomes higher. Show.
Note that FIG. 3 also shows the intensity for each frequency component of the rectangular wave as a proportional. As described above, it can be seen that the ratio of the plurality of harmonic components is larger in the waveform of the resistance current Ir shown in FIG. 2 than in the rectangular wave.

FIG. 4 is a diagram for explaining the influence of the parasitic capacitance in the lightning arrester according to the first embodiment.
Hereinafter, the influence of the parasitic capacitance 201 superimposed on the lightning arrester 20 will be described with reference to FIGS. 1 and 4A to 4D.
The graphs shown in FIGS. 4A to 4D show examples of changes over time in the supply voltage, the capacitance current Ic, the resistance current Ir, and the total leakage current Io applied to the overhead line 10, respectively. . In this example, the supply voltage applied to the overhead line 10 is superimposed with a harmonic component (noise component) specific to the power system including the overhead line 10 in addition to the fundamental wave as shown in FIG. (Because the harmonic component is very small, it does not appear in the graph shown in FIG. 4A). Since this harmonic component is a signal having a high frequency, it easily passes through the parasitic capacitance 201. Therefore, as shown in FIG. 4B, the capacitance-divided current Ic has a waveform in which harmonic components that vibrate at a higher frequency than the fundamental wave are superimposed.

On the other hand, when the insulation characteristic of the nonlinear resistance element 200 is deteriorated, as shown in FIGS. 2 and 4C, the resistance current Ir is alternately sine wave in the positive and negative directions every half cycle of the supply voltage. Becomes a protruding waveform.
From the above, the total leakage current Io that can be actually observed is the current generated due to noise inherent in the power system (capacitance component current Ic) and deterioration of the nonlinear resistance element 200, as shown in FIG. It becomes a combined current with (resistive component current Ir).

  In this manner, since the lightning arrester 20 is electrically added with the parasitic capacitance 201, the noise component (capacitance component current Ic) inherent to the power system is added to the total leakage current Io, and the resistance component that is originally desired to be observed. The current Ir is buried. Therefore, in a normal analysis, it is difficult to detect the deterioration of the nonlinear resistance element 200 based on the resistance current Ir.

FIG. 5 is a diagram illustrating the function of the current detection sensor according to the first embodiment.
The current detection sensor 300 according to the first embodiment is proportional to both the magnitude of the total leakage current Io including the leakage current (resistance current Ir) flowing through the nonlinear resistance element 200 and the frequency of the total leakage current Io. It is possible to output a detection signal having the specified intensity.
In general, a voltage (excitation voltage V) excited by a coil (current detection sensor 300 which is a Rogowski coil in the case of this embodiment) arranged so as to surround a wiring through which a current to be observed flows is, As shown in Expression (1), the differential value of the current to be observed is shown.

In Equation (1), ω is the angular frequency of the alternating current and a value proportional to the frequency f (ω = 2πf), I is the amplitude of the alternating current, and L is the self-inductance of the coil.
Therefore, normally, the current value to be observed can be obtained by inputting and integrating the excitation voltage V directly observed by the coil into the integrating circuit. However, in this embodiment, the excitation voltage V excited by the Rogowski coil (current detection sensor 300) is taken directly into the main body 310 and processed without using an integration circuit. By doing in this way, the main-body part 310 acquires the detection signal output with the intensity | strength proportional to both the magnitude | size of the electric current, and the frequency of the said electric current through the electric current detection sensor 300 (refer Formula (1)). ).

  The frequency component acquisition unit 311 performs Fourier transform processing on the detection signal output from the current detection sensor 300 (excitation voltage signal proportional to both the magnitude of the total leakage current Io and the frequency of the total leakage current Io). (Or bandpass filter processing) is performed to acquire the intensity for each frequency component.

The graph shown in FIG. 5 is the intensity for each frequency component of the detection signal output from the current detection sensor 300 obtained by the Fourier transform process of the frequency component acquisition unit 311. As shown in FIG. 5, the detection signal proportional to both the current and its frequency changes so as to rise and then fall as the order increases from the primary (fundamental wave) to the higher order.
Here, as shown in FIG. 3, the resistance current Ir when the nonlinear resistance element 200 is degraded contains a relatively large number of harmonic components from the third order to the fifteenth order. The current detection sensor 300 outputs a detection signal that increases in proportion to both the current and its frequency. Therefore, as shown in FIG. 5, the detection signal obtained by the current detection sensor 300 has an intensity distribution in which the intensity is emphasized as the harmonic component has a higher order and changes to draw a mountain locus.

FIG. 6 is a diagram illustrating the function of the leakage current determination unit according to the first embodiment.
6A and 6B show the calculation result (content [mV]) of the frequency component of the detection signal output from the current detection sensor 300. FIG. The graph shown in FIG. 6A shows an example of a calculation result when the nonlinear resistance element 200 is not deteriorated. Further, the graph shown in FIG. 6B shows an example of a calculation result when the nonlinear resistance element 200 is deteriorated.

When the non-linear resistance element 200 is not deteriorated, the resistance current Ir becomes zero, but a noise component (electrostatic amount domain current Ic) of the power system propagating through the parasitic capacitance 201 is observed. As shown in FIG. 4, a detection result in which some harmonic components (21st to 25th harmonic components, etc.) exceed the determination threshold (= 1 mV) is obtained.
Here, the leakage current determination unit 312 according to the present embodiment causes a leakage current to flow through the nonlinear resistance element 200 when, for example, 10 or more consecutive odd-order harmonic components exceed the determination threshold (= 1 mV). It is determined that Therefore, even if a detection result as shown in FIG. 6A is obtained, the leakage current determination unit 312 does not determine that a leakage current is flowing through the nonlinear resistance element 200.

On the other hand, when the nonlinear resistance element 200 is deteriorated, the resistance current Ir flows in a pulsed waveform as shown in FIG. Then, as shown in FIG. 6B, the detection result exceeds the determination threshold value (= 1 mV) over the harmonic components from the third order to the 43rd order. This is because the resistance current Ir flowing when the nonlinear resistance element 200 is deteriorated includes a plurality of continuous harmonic components (see FIG. 3), and the current detection sensor 300 has higher harmonics. This is because the wave component is emphasized and detected (see FIG. 5).
According to the detection result as shown in FIG. 6B, 10 or more consecutive odd-order harmonic components exceed the determination threshold (= 1 mV). Therefore, the leakage current determination unit 312 according to the present embodiment determines that a leakage current is flowing through the nonlinear resistance element 200.

As described above, the leakage current determination unit 312 according to the present embodiment performs nonlinear processing when the intensity of a plurality of harmonic components that are a predetermined number or more of odd-numbered harmonic components exceeds a predetermined determination threshold. It is determined that a leakage current flows through the resistance element 200.
That is, as shown in FIG. 6A, the frequency component detected only by the capacitance divided current Ic has an irregular distribution according to the noise characteristic specific to the power system, and over a specific frequency range. There is no tendency to continuously exceed the determination threshold. However, when the non-linear resistance element 200 deteriorates and a pulse-like resistance current Ir appears, as shown in FIG. 6B, higher-order harmonics in a specific frequency range continuously set the determination threshold. It shows a tendency to exceed. The leakage current determination unit 312 according to this embodiment determines whether or not the resistance current Ir is flowing by using the above characteristics of the resistance current Ir. Therefore, the leakage current determination unit 312 can accurately determine whether or not the leakage current is flowing even if a noise component specific to the power system is included.

  Further, the current detection sensor 300 according to the present embodiment is a coil attached so as to surround the ground line g (FIG. 1) through which the total leakage current Io flows. Further, the frequency component acquisition unit 311 according to the present embodiment inputs a voltage (detection signal) excited by the current detection sensor 300 that is the coil without passing through an integration circuit, and generates harmonics of the excited voltage. Get the strength of each component. By doing in this way, the whole structure of the detection apparatus 30 can be simplified.

  As mentioned above, although the electric power supply system 1 which concerns on 1st Embodiment was demonstrated in detail, the specific aspect of the electric power supply system 1 which concerns on this embodiment is not limited to the above-mentioned thing, and deviates from a summary. It is possible to add various design changes and the like within the range not to be performed.

FIG. 7 is a diagram illustrating the function of the leakage current determination unit according to the modification of the first embodiment.
FIG. 7 shows the calculation result (content [mV]) of the frequency component of the detection signal output from the current detection sensor 300, as in FIGS. 6 (a) and 6 (b). The graph shown in FIG. 7 shows an example of the calculation result when the degree of deterioration of the nonlinear resistance element 200 is smaller than the case shown in FIG.

Here, the leakage current determination unit 312 according to the modification of the first embodiment simply determines the intensity of a plurality of harmonic components equal to or greater than a predetermined number, regardless of whether or not the harmonic order is continuous. When the threshold value is exceeded, it may be determined that a leakage current flows through the nonlinear resistance element 200.
For example, the leakage current determination unit 312 according to the modification includes 10 or more harmonic components among the odd-order harmonic components from the 5th to the 39th order in which high strength is expected when the resistance current Ir is generated. Is greater than the determination threshold (= 1 mV), it is determined that a leakage current is flowing through the nonlinear resistance element 200. By doing so, the leakage current determination unit 312 according to this modification example has a leakage current flowing through the non-linear resistance element 200 even when the degree of progress of deterioration is small as shown in FIG. Is determined. Therefore, it is possible to detect the deterioration of the nonlinear resistance element 200 relatively early.

  Moreover, when the frequency distribution of the noise component (specific harmonic component superimposed on the supply voltage of the overhead wire 10) can be grasped by the prior measurement / experiment, the following may be performed. That is, the leakage current determination unit 312 determines that a leakage current flows through the nonlinear resistance element 200 when at least one specific harmonic component that is less affected by noise exceeds a determination threshold among the harmonic components. It is good also as what to do.

  Furthermore, when the frequency distribution of the noise component can be grasped, the leakage current determination unit 312 sets a plurality of determination thresholds that are different for each harmonic component of the detection signal according to the frequency distribution of the noise component. Also good. In this case, the leakage current determination unit 312 may determine that a leakage current is flowing through the nonlinear resistance element 200 when a predetermined number or more of harmonic components exceed the corresponding determination threshold.

  Furthermore, the leakage current determination unit 312 in each of the above-described embodiments can change the determination threshold, the number of harmonics (the number of continuous harmonic components), or the like as desired by the operation of the administrator of the power supply system 1. An aspect may be sufficient. By doing in this way, the manager can optimize a judgment standard according to the lightning arrester 20 to be used or the characteristic peculiar to the power supply system 1.

In addition, the leakage current determination unit 312 according to each of the above-described embodiments has been described as a fixed threshold value (for example, 1 mV) that is defined in advance. However, the other embodiments are not limited to this mode.
For example, the leakage current determination unit 312 according to another modification may use the determination threshold as the intensity of the fundamental wave component (first order) of the detection signal from the current detection sensor 300. Here, as shown in FIG. 5, the harmonic component of the leakage current (resistance current Ir, see FIG. 2) generated when the non-linear resistance element 200 is deteriorated is more fundamental than the fundamental component over a predetermined range. It can be seen that it has a large strength. Therefore, it is possible to detect the deterioration of the nonlinear resistance element 200 with higher accuracy by determining the presence or absence of leakage current in the nonlinear resistance element 200 based on the number of harmonic components exceeding the intensity of the detected fundamental wave component. it can.

  Moreover, although the current detection sensor 300 according to each of the above-described embodiments has been described as a Rogowski coil capable of accurately detecting a current flowing through the inside, the current detection sensor 300 according to another modification is not limited to the other. Different aspects may be possible. In other words, the current detection sensor 300 is in any form as long as it can output a detection signal having an intensity proportional to both the magnitude of the total leakage current Io to be detected and the frequency of the total leakage current Io. It doesn't matter.

As mentioned above, according to the detection apparatus 30 which concerns on each above-mentioned embodiment, degradation of the lightning arrester 20 can be detected accurately.
Moreover, according to the detection apparatus 30 which concerns on each above-mentioned embodiment, since the soundness of the lightning arrester 20 can be monitored in real time during operation | movement of the electric power supply system 1, it requires for the evaluation of the soundness of the said lightning arrester 20 concerned. Labor and cost can be reduced.
In addition, the detection device 30 according to each of the above-described embodiments includes a coil (current detection sensor 300) attached to the ground line g (FIG. 1), and a computer that inputs and processes a detection signal from the current detection sensor 300 ( It can be realized with a configuration of only the main body 310). Therefore, the entire configuration of the detection device can be simplified.

FIG. 8 is a diagram illustrating an installation example of the detection device according to the first embodiment.
As shown in FIG. 8, the lightning arrester 20 is supported by a support column 21 provided on the ground surface.
The current detection sensor 300 is attached so as to surround the ground wire g connected to the lightning arrester 20 and the entire support column 21. Here, it is assumed that the total leakage current flowing from the overhead wire 10 to the ground surface (the ground contact point G) propagates not only through the ground wire g but also through the support column 21. Therefore, as shown in FIG. 8, by attaching a coil (current detection sensor 300) so as to surround the ground line g and the entire support column 21, the total leakage current including the current flowing through the support column 21 is observed. Can do.

In each of the above-described embodiments, a program for realizing the function of the detection device 30 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed. Each procedure is to be performed. Here, each process of the detection device 30 described above is stored in a computer-readable recording medium in the form of a program, and the above-described various processes are performed by the computer reading and executing the program. Here, the computer-readable recording medium refers to a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, and the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.
In addition, each functional configuration of the detection device 30 may be provided across a plurality of devices connected via a network.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof, as long as they are included in the scope and gist of the invention.

DESCRIPTION OF SYMBOLS 1 Electric power transmission system 10 Overhead line 20 Lightning arrester 21 Support pillar 200 Nonlinear resistance element 201 Parasitic capacitance 30 Detection apparatus 300 Current detection sensor 310 Main-body part 311 Frequency component acquisition part 312 Leakage current determination part

Claims (6)

A detection device for detecting a leakage current flowing in a non-linear resistance element,
A current detection sensor capable of outputting a detection signal having an intensity proportional to both the magnitude of the total leakage current including the leakage current flowing through the nonlinear resistance element and each frequency component included in the total leakage current;
A frequency component acquisition unit for acquiring the intensity of each harmonic component of the detection signal;
A leakage current determination unit that determines whether or not a leakage current flows through the nonlinear resistance element based on the acquired intensity for each harmonic component;
Equipped with a,
The leakage current determination unit
The detection apparatus which determines that the said leakage current is flowing, when the intensity | strength of the said several or more harmonic component more than predetermined number among the intensity | strengths for every said harmonic component exceeds the predetermined determination threshold value . The leakage current determination unit
It is determined that the leakage current is flowing when the intensity of a plurality of the harmonic components that are a predetermined number or more of the odd-order harmonic components exceeds the determination threshold.
The detection device according to claim 1 . The leakage current determination unit
The determination threshold is the intensity of the fundamental wave component of the detection signal.
The detection device according to claim 1 or 2 . The current detection sensor is a coil attached so as to surround a ground wire through which the total leakage current flows.
The detection device according to any one of claims 1 to 3 , wherein the frequency component acquisition unit acquires the intensity of each harmonic component of the detection signal that is a voltage excited in the coil. The detection device according to any one of claims 1 to 4 ,
A lightning arrester having the non-linear resistance element;
An overhead wire to which an AC voltage is applied;
A power supply system comprising: A detection method for detecting a leakage current flowing in a non-linear resistance element,
Outputting a detection signal having an intensity proportional to both the magnitude of the total leakage current including the leakage current flowing through the nonlinear resistance element and each frequency component included in the total leakage current;
Obtaining the intensity of each harmonic component of the detection signal;
Determining whether or not a leakage current flows through the nonlinear resistance element based on the obtained intensity for each harmonic component; and
I have a,
The step of determining whether or not the leakage current is flowing further comprises
A detection method including a step of determining that the leakage current is flowing when the intensity of a plurality of the harmonic components equal to or greater than a predetermined number among the intensities of the harmonic components exceeds a predetermined determination threshold. .

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