JP7420337B2 - Power distribution system exploration system - Google Patents

Description

The present invention relates to a technique for detecting an abnormality occurring in a power distribution system including at least an overhead wiring section.

Electric power generated at a power plant is carried by transmission lines to a substation, where it is converted to a predetermined voltage, and then carried to the consumers who consume the electricity by distribution lines. In urban areas, electricity is carried to consumers via underground distribution lines, but in other areas, electricity is carried to consumers via overhead distribution lines.

Since overhead power distribution lines are located outdoors, there are more factors that can cause accidents than underground power distribution lines. For example, a tree may come into contact with an overhead power distribution line, or a bird or animal may come into contact with an overhead power distribution line. In the unlikely event that such an accident occurs, it is necessary to search for the point and cause of the accident as early as possible, eliminate the cause of the accident, and perform recovery.

JP 2018-031718A (Patent Document 1) discloses an overhead power distribution system exploration system that can search for fault points occurring in an overhead power distribution system in a shorter time.

JP2018-031718A

According to the above-mentioned overhead power distribution system exploration system disclosed in Patent Document 1, fault points that occur in the overhead power distribution system can be searched for in a shorter time, but when considering actual operation, the section where an accident can occur is vast. , a single overhead power distribution system search device may not be able to adequately cover the situation.

The present invention has been made to solve such problems, and its purpose is to provide an overhead power distribution system exploration system suitable for actual operation.

According to one aspect of the present invention, there is provided a power distribution system exploration system for exploring an abnormality occurring in a power distribution system including at least an overhead wiring section. The power distribution system exploration system includes a plurality of measuring devices arranged at different positions in the power distribution system, and a processing device that processes the respective measurement results obtained by the plurality of measuring devices. Each of the plurality of measuring devices includes a pulse generator that generates a pulsed incident wave, and a detector that outputs as a measurement result an electrical change that occurs in the power distribution system due to the incident wave generated by the pulse generator. When a measurement result from one of the plurality of measurement devices satisfies a predetermined abnormality determination condition, the processing device detects the measurement result from another measurement device located near the measurement device that satisfies the abnormality determination condition. The location of the abnormality in the power distribution system is determined by also referring to the measurement results.

Preferably, the processing device determines the position where the abnormality occurs based on the situation when the target measuring device measures the time waveform.

Preferably, the abnormality determination condition is determined depending on measurement results over a predetermined immediately preceding period.

Preferably, the pulse generator is configured to inject the incident wave into the power distribution system via capacitive coupling.

Preferably, each of the plurality of measuring devices is disposed between the pulse generator and the power distribution system, and guides the incident wave from the pulse generator to the power distribution system, and also receives reflected waves corresponding to the incident wave from the power distribution system. It further includes a directional coupler leading to the detection section.

Preferably, the power distribution system exploration system further includes a ferrite core that is placed on any of the branch paths included in the power distribution system and that guides an incident wave from any of the measurement devices to a specific path among the branch paths. The processing device determines the location of an abnormality that may occur in the power distribution system depending on the location of the ferrite core.

According to the present invention, an overhead power distribution system exploration system suitable for actual operation can be realized.

FIG. 1 is a schematic diagram showing a configuration example of a power distribution system exploration system according to the present embodiment. FIG. 2 is a diagram for explaining an overview of TDR measurement used in the power distribution system exploration system according to the present embodiment. FIG. 2 is a schematic diagram showing an example of the hardware configuration of a measuring device used in the power distribution system exploration system according to the present embodiment. 4 is a diagram for explaining the function of the directional coupler shown in FIG. 3. FIG. FIG. 3 is a diagram for explaining a voltage shift in TDR measurement used in the power distribution system exploration system according to the present embodiment. An example of measurement results for evaluating the influence of voltage shift by the measurement device according to the present embodiment is shown. FIG. 3 is a diagram for explaining the injection timing of pulse waves by the measuring device according to the present embodiment. It is a figure which shows the example of a result of accident point location of the short circuit accident by the measuring device according to this Embodiment. It is a figure which shows the example of a result of accident point location of the ground fault accident by the measuring device according to this Embodiment. It is a figure showing an example of the temporal fluctuation of the measurement result acquired by the measurement device according to this embodiment. FIG. 3 is a diagram illustrating an example of evaluation of temporal fluctuations occurring in measurement results obtained by the measurement device according to the present embodiment. It is a figure for explaining the processing procedure of fault point location in the power distribution system exploration system according to this embodiment. It is a flowchart which shows the processing procedure concerning position locating by the measuring device according to this embodiment. An example of measurement results obtained by the measuring device according to the present embodiment in a state where tree contact occurs on the simulated track is shown. An example of measurement results obtained by the measuring device according to the present embodiment in a state where an insulator defect has occurred on a simulated line is shown. 2 is a flowchart showing a processing procedure for detecting an unusual state by the measuring device according to the present embodiment. FIG. 2 is a diagram for explaining a simulated track for evaluating fault point location based on fault current flowing during an accident. An example of measurement results obtained while a short circuit accident occurs on the simulated line shown in FIG. 17 is shown. An example of measurement results obtained during the occurrence of a ground fault accident on the simulated line shown in FIG. 17 is shown. FIG. 3 is a diagram for explaining an example of operation of abnormality exploration in the power distribution system exploration system according to the present embodiment. It is a flowchart which shows the processing procedure concerning abnormality exploration in the power distribution system exploration system according to this embodiment. FIG. 3 is a diagram showing an example of a simulated line for evaluating the interrupting performance of a ferrite core in the power distribution system exploration system according to the present embodiment. An example of a time waveform measured on the simulated line shown in FIG. 22 is shown.

Embodiments of the present invention will be described in detail with reference to the drawings. Note that the same or corresponding parts in the figures are given the same reference numerals and the description thereof will not be repeated.

<A. Overview of power distribution system exploration system>
First, the configuration, measurement method, etc. of the power distribution system exploration system 1 according to the present embodiment will be outlined.

In the operation of a normal power distribution system, automatic sectional switches that divide the power distribution system into sections and a distribution automation system that controls the automatic sectional switches are used. When an accident occurs in the power distribution system, the power distribution automation system identifies the section where the accident occurred and resumes power transmission to healthy sections where no accident has occurred. Although power distribution automation systems can identify the section where an accident has occurred, the section is relatively long, so it is necessary to carry out an investigation (typically by a worker such as track patrol or overhead line detection) to pinpoint the actual accident point. work) is required. Note that identification numbers of utility poles and the like are used to identify the accident point (also referred to as "location").

In contrast, the power distribution system exploration system 1 automatically searches for abnormalities occurring in the power distribution system including at least overhead wiring sections. In this specification, the term "abnormality that occurs in the power distribution system" refers to a state in which some kind of accident has occurred, such as a short circuit, a ground fault, or a disconnection, as well as a state that is different from normal (for example, the leakage current is higher than normal). etc.).

FIG. 1 is a schematic diagram showing a configuration example of a power distribution system exploration system 1 according to the present embodiment. Referring to FIG. 1, a power distribution system exploration system 1 targets one or more power distribution systems 2 to which power is supplied from a substation 4. The power distribution system 2 includes at least an overhead wiring section.

The power distribution system exploration system 1 includes a plurality of measurement devices 100 arranged at different positions of the power distribution system 2. The measurement device 100 uses time domain reflectometry (TDR) measurement to obtain measurement results 10 necessary for investigating an abnormality occurring in the power distribution system 2. Typically, the measuring device 100 can be placed independently at any position in the power distribution system 2, or can be incorporated as part of equipment (for example, a switch or a pole transformer) placed in the power distribution system 2. You can also do that.

The power distribution system exploration system 1 further includes a processing device 200 that processes each measurement result 10 obtained by the plurality of measurement devices 100. More specifically, when the measurement result 10 from any one of the plurality of measurement devices 100 satisfies a predetermined abnormality determination condition, the processing device 200 selects a measurement device that satisfies the abnormality determination condition. The position where the abnormality has occurred in the power distribution system 2 is determined by also referring to the measurement results 10 of other measuring devices 100 located in the vicinity of the power distribution system 100 . In addition to the function of identifying the location of an abnormality that has occurred in the power distribution system 2 (locating the fault point) (fault point locating function), the processing device 200 also has the ability to It may also have a function (accident type identification function) to identify faults such as faults, disconnections, etc. Details of the processing executed by the processing device 200 will be described later.

FIG. 2 is a diagram for explaining an overview of TDR measurement used in the power distribution system exploration system 1 according to the present embodiment. Referring to Figure 2, the procedure for TDR measurement is (1) sending out a pulse wave towards the accident point, (2) sending out the pulse wave until the pulse wave reflected at the accident point arrives. Measure the time (ie round trip time t). Assuming that the propagation speed of the pulse wave is v, L from the measuring device 100 to the accident point can be expressed as follows.

L=v×t/2
Since impedance changes occur at the fault point, a method of injecting a pulse wave into the distribution system 2 and calculating the distance from the reflected wave generated by reflecting at the fault point is applied to calculate the difference between the measurement results before and after the fault. This allows you to locate the accident point.

However, when the load current flowing through the power distribution system 2 is large, the amplitude of the injected pulse wave becomes relatively small, and a difference may remain in the reflected waves before the fault point. In addition, when a method of injecting pulses through a current probe is adopted, if the load current flowing through the distribution system 2 is large, magnetic saturation occurs in the current probe, making it difficult to inject an appropriate pulse wave into the distribution system 2. may not be possible.

Therefore, the measuring device 100 configuring the power distribution system exploration system 1 according to the present embodiment adopts a method of injecting pulses into the power distribution system 2 via capacitive coupling.

<B. Example of hardware configuration of measuring device 100>
Next, an example of the hardware configuration of the measuring device 100 used in the power distribution system exploration system 1 according to the present embodiment will be described.

FIG. 3 is a schematic diagram showing an example of the hardware configuration of measurement device 100 used in power distribution system exploration system 1 according to the present embodiment. Referring to FIG. 3, measurement device 100 includes a measurement unit 110 for generating an incident wave (pulse wave) to be injected into power distribution system 2 and collecting reflected waves generated in power distribution system 2; It includes a coupling part 140 for electrically connecting to the power distribution system 2 . The measuring device 100 may be housed in a resin case that is easy to work with.

Measuring section 110 and coupling section 140 are electrically connected via coaxial cable 104 to reduce noise. Figure 3 shows an example of a configuration that can measure two phases (two wires: represented as "CH1" and "CH2") included in the power distribution system 2, but a configuration that can measure more phases is adopted. You can.

The measurement section 110 includes a main control section 106 , amplifiers 120 and 130 , directional couplers 122 and 132 , and a pulse transformer board 102 . Main control section 106 includes a pulse generator 112, an A/D (Analog to Digital) converter 114, a calculation section 116, and a communication section 118.

The pulse generator 112 generates a predetermined pulse-like incident wave periodically or at arbitrary timing. The pulse wave generated by the pulse generator 112 is supplied to the amplifiers 120 and 130 from the transmission port of the main control unit 106.

The A/D converter 114 receives the signals (including the reflected wave component of the pulse wave) output from the directional couplers 122 and 132, and outputs a digital signal indicating the waveform. The calculation unit 116 processes the digital signal output from the A/D converter 114 and generates the measurement result 10. Details of the process for generating the measurement result 10 will be described later. In this way, the A/D converter 114 and the arithmetic unit 116 output the electrical changes that occur in the power distribution system 2 due to the incident wave generated by the pulse generator 112 as the measurement result 10.

The communication unit 118 transmits the measurement results generated by the calculation unit 116 to the processing device 200 or the like. The communication unit 118 may adopt a method of transmitting signals through conductors that constitute the power distribution system 2, or may employ a wireless communication method such as LTE (Long Term Evolution) or wireless LAN (Local Area Network). You may.

Amplifiers 120 and 130 amplify the pulse waves generated by pulse generator 112 and supply the amplified pulse waves to directional couplers 122 and 132.

The directional couplers 122 and 132 are arranged between the pulse generator 112 and the power distribution system 2, and guide the incident wave (pulse wave) from the pulse generator 112 to the power distribution system 2, and also guide the incident wave (pulse wave) from the power distribution system 2. A signal (including a reflected wave corresponding to the incident wave (pulse wave)) is guided to the reception port (A/D converter 114) of the main control unit 106.

The pulse transformer board 102 includes an interface circuit for transmitting an incident wave including a pulse wave and a reflected wave including a reflected wave component of the pulse wave. More specifically, the pulse transformer board 102 is electrically connected to the directional couplers 122 and 132, and is also electrically connected to the coupling section 140 via the coaxial cable 104.

FIG. 4 is a diagram for explaining the functions of the directional couplers 122 and 132 shown in FIG. 3. Directional couplers 122, 132 include circuitry that can direct a portion of a signal that enters from one port and propagates in a particular direction to another port.

Referring to FIG. 4, when an incident wave (pulse wave) sent out from main control unit 106 is applied to port P1 of directional couplers 122, 132, it passes through directional couplers 122, 132, It is output from P2 to the power distribution system 2 side. At this time, the incident wave is not substantially guided to the port P3 side.

On the other hand, when a reflected wave from the power distribution system 2 side enters port P2 of the directional couplers 122, 132, a filtered result according to the frequency characteristics of the incident reflected wave is output from port P3 (and port P1). Ru. As for frequency characteristics, by employing a low frequency cut filter, the influence of the commercial frequency (60 Hz or 50 Hz) appearing in the power distribution system 2 can be cut. Measurement section 110 according to this embodiment employs a low frequency cut filter that cuts approximately 40 dB.

In this way, the directional couplers 122 and 132 remove the influence of the incident wave (pulse wave) sent out from the main control unit 106 and transmit the reflected wave from the power distribution system 2 to the receiving circuit of the main control unit 106 ( It can be observed with the A/D converter 114). At this time, the influence of the commercial frequency (60 Hz or 50 Hz) appearing in the power distribution system 2 can be cut by filtering by the measuring unit 110.

By employing the directional couplers 122 and 132, the transmitting circuit (pulse generator 112) and receiving circuit (A/D converter 114) of the main control section 106 can be incorporated into the same transmission line.

Note that instead of the directional couplers 122 and 132, a switching circuit capable of high-speed switching may be employed.

Referring again to FIG. 3, coupling section 140 includes a coupling circuit 142 and a high voltage capacitor 144. The high-voltage capacitor 144 is a member that capacitively couples the measuring device 100 to the power distribution system 2 to be investigated. The high voltage capacitor 144 is preferably a relatively large capacitor with a capacitance of about 1000 pF, for example. The pulse generator 112 is thus configured to inject an incident wave (pulse wave) into the power distribution system 2 via capacitive coupling.

Coupling circuit 142 matches the electrical connection between coaxial cable 104 and high voltage capacitor 144 .

Note that a matching circuit may be placed in the path from the transmission circuit (pulse generator 112) of the main control unit 106 to the power distribution system 2. By arranging such a matching circuit, re-reflections (multiple reflections) on the power supply side can be reduced.

However, if the receiving level of the reflected wave is reduced by arranging the matching circuit, the matching circuit may not be provided as shown in FIG. 3. By omitting the matching circuit, a pulse wave with a larger amplitude can be injected into the power distribution system 2.

In the measuring device 100, a pulse wave is injected into each phase included in the power distribution system 2, and the respective ground potentials appearing in the phases into which the pulse waves are injected (each ground potential appearing in CH1 and CH2) can also be measured. It is also possible to measure the potential difference that appears between the phases (the differential voltage between CH1 and CH2). In the following description, the same pulse wave is injected into two phases connected to the measuring device 100, and the resulting potential difference (differential waveform) appearing between the phases is taken as the measurement result. By using a differential waveform, common mode noise can be canceled out, and determination processing etc. can be facilitated. Instead of such a differential waveform, a potential difference appearing in either phase may be used as the measurement result.

In the following description, the term "difference" or "difference waveform" may be used. It should be noted that "difference" or "difference waveform" refers to the difference between any two "differential waveforms", and that "differential" and "difference" are used with different meanings.

<C. TDR measurement>
Next, TDR measurement used in the power distribution system exploration system 1 according to this embodiment will be explained. In TDR measurement, the occurrence of an abnormality or a sign of its occurrence is detected based on the difference obtained by comparing a measurement result in a steady state where no abnormality occurs and a measurement result in a target state.

FIG. 5 is a diagram for explaining a voltage shift in TDR measurement used in the power distribution system exploration system 1 according to the present embodiment. Referring to FIG. 5, the pulse wave injected into the power distribution system 2 is superimposed on the large amplitude wave of the detected voltage generated by the load current. The detected voltage generated by the load current fluctuates over time with a period of about 16.7 ms (in the case of a commercial frequency of 60 Hz), but since the pulse width of the pulse wave is about several tens to several hundred ns, the measurement is based on the load current. This is performed for an extremely short period of time (several hundred ns to several μs) compared to the fluctuation period of . Therefore, there is a possibility that the pulse wave is measured in a state where it appears to have been shifted by the magnitude of the load current at the timing at which the pulse wave was injected.

However, by employing the measuring device 100 according to this embodiment, the influence of such a voltage shift can be substantially ignored.

FIG. 6 shows an example of measurement results for evaluating the influence of voltage shift by the measurement device 100 according to the present embodiment. FIG. 6 shows the results of measurements made using a simulated line. Figure 6 (A) shows a case in which power is being supplied to the simulated line in a steady state (a state in which no accident has occurred) (charging (steady state)), and a case in which the simulated line is in a steady state (in a state in which no accident has occurred). The time waveforms obtained by injecting pulse waves into the power distribution system 2 are shown for each of the cases in which power is not supplied (power outage (steady state)) and when power is not being supplied (state in which no electricity is occurring). FIG. 6(B) shows the difference between the two time waveforms shown in FIG. 6(A).

While the dynamic range of the receiving circuit (A/D converter 114) of the measurement device 100 is ±0.5V, as shown in FIG. 6(B), the difference between the two time waveforms (difference waveform) is , has an amplitude of only ±0.03V at maximum. In other words, the difference between when power is being supplied to the power distribution system 2 and when it is not is extremely small at 4 to 6% with respect to the dynamic range of the receiving circuit of the measuring device 100, so the voltage shift caused by the commercial frequency is extremely small. The impact is virtually negligible.

Note that such a remarkable effect is thought to be brought about by the action of the frequency filter by the pulse transformer board 102, the directional couplers 122, 132, and the like.

As described above, when the measuring device 100 according to this embodiment is employed, there is no need to consider the shift component (shift voltage) caused by the load current. Therefore, it is not necessary to obtain in advance both the measurement results when pulse waves are injected into the power distribution system 2 and the measurement results when pulse waves are not injected.

FIG. 7 is a diagram for explaining the pulse wave injection timing by the measuring device 100 according to the present embodiment. FIG. 7(A) shows the injection timing when using a measurement device in which the effects of voltage shifts must be removed. As shown in FIG. 7A, in order to eliminate the influence of voltage shift, it is necessary to obtain measurement results with pulse waves injected and measurement results without pulse waves injected at the same timing. That is, by adjusting the measurement and pulse wave injection timing to the phase of the commercial frequency, the influence of voltage shift is fixed, and by differentiating the measurement results, the influence of voltage shift is removed. However, in the measurement shown in FIG. 7A, there is a constraint that the injection timing of the pulse wave is fixed, and the injection frequency is also constrained.

On the other hand, in the measuring device 100 according to the present embodiment, the influence of voltage shift can be substantially ignored, so there is no need to fix the injection timing of the pulse wave to a specific phase of the commercial frequency, which is convenient for the measuring device 100. Pulse waves can be injected at any timing. This makes it possible to increase the frequency of pulse wave injection and measurement, thereby reducing noise through time diversity synthesis and the like, thereby making measurements more stable.

Hereinafter, a measurement example of accident point location using the measuring device 100 according to the present embodiment will be described. The following measurement results were measured using the measuring device 100 while causing a short circuit accident and a ground fault accident on a simulated line. Note that the distance from the measuring device 100 to each accident point is 250.5 [m].

FIG. 8 is a diagram illustrating an example of the result of accident point location of a short circuit accident by the measuring device 100 according to the present embodiment. Figure 8 (A) shows the measurement results (healthy (charged)) when the simulated line is in a steady state (no accident has occurred) and when a short circuit accident has occurred on the simulated line. The measurement results (short circuit (power outage)) are shown. FIG. 8(B) shows the difference between the two time waveforms shown in FIG. 8(A).

As described above, in the measurement device 100 according to this embodiment, the influence of voltage shifts caused by commercial frequencies can be substantially ignored. Therefore, by calculating the difference between the measurement results obtained before and after the occurrence of an abnormality, it is possible to detect an accident and locate the accident point.

In the time waveform difference (difference waveform) shown in FIG. 8(B), since the round trip time to the accident point is 1750 [ns], the distance to the accident point can be calculated as 256.4 [m]. Since the actual distance to the accident point is 250.5 [m], the orientation error is approximately 5.9 [m] (orientation error: approximately 2.4%), which has sufficient orientation accuracy. I understand that.

FIG. 9 is a diagram illustrating an example of the result of locating the accident point of a ground fault accident using the measuring device 100 according to the present embodiment. Figure 9 (A) shows the measurement results (healthy (charged)) when the simulated line is in a steady state (no accident has occurred), and when a ground fault has occurred on the simulated line. Shows the measurement results (earth fault (power outage)). FIG. 9(B) shows the difference between the two time waveforms shown in FIG. 9(A).

In the time waveform difference (difference waveform) shown in FIG. 9(B), since the round trip time to the accident point is 1750 [ns], the distance to the accident point can be calculated as 256.4 [m]. Since the actual distance to the accident point is 250.5 [m], the orientation error is approximately 5.9 [m] (orientation error: approximately 2.4%), which has sufficient orientation accuracy. I understand that.

Note that the measurement results obtained for the ground fault shown in Figure 9 (B) show an increase in noise compared to the measurement results obtained for the short circuit fault shown in Figure 8 (B). It will be done.

<D. How to determine the reference waveform>
Next, a method for determining a time waveform (hereinafter also referred to as a "reference waveform") that serves as a reference for detecting abnormalities occurring in the power distribution system will be described.

The measured time waveform may change due to changes in the surrounding conditions of the power distribution system 2 (typically, the influence of weather). Therefore, it is preferable that the reference waveform for detecting abnormalities occurring in the power distribution system is not fixedly determined in advance, but uses a time waveform measured in the immediately preceding predetermined period.

FIG. 10 is a diagram showing an example of temporal fluctuations in measurement results obtained by measurement device 100 according to the present embodiment. FIG. 10(A) shows an example of the difference (difference waveform) between time waveforms acquired at 5-minute intervals, and FIG. 10(B) shows an example of the difference (difference waveform) between time waveforms acquired at 1-minute intervals. An example is shown. For example, "5 minutes - 10 minutes" in the table means the difference between the time waveform obtained when 5 minutes have elapsed from the reference time and the time waveform obtained when 10 minutes have elapsed from the reference time.

As shown in FIG. 10, the acquired time waveform varies under the influence of the surrounding situation of the power distribution system 2. However, when comparing FIG. 10(A) and FIG. 10(B), the degree of influence can be reduced by shortening the measurement interval (from 5 minute intervals to 1 minute interval). Therefore, the measurement interval between the reference waveform for detecting abnormalities occurring in the power distribution system and the target measurement result needs to be appropriately set depending on the situation.

FIG. 11 is a diagram illustrating an example of evaluation of temporal fluctuations occurring in measurement results obtained by measurement device 100 according to the present embodiment. FIG. 11 shows the results of evaluating temporal fluctuations that occur in measurement results by varying measurement intervals. In FIG. 11, the absolute value of the difference amount indicates the maximum value of the amplitude of the difference waveform.

In addition, in each measurement, the time waveform (for example, measurement period 3 [ms]) was repeatedly measured the number of times according to the measurement interval, and averaging processing was performed.

As shown in FIG. 11, as the measurement interval becomes longer, the absolute value of the difference tends to increase. On the other hand, when the measurement interval is too short, the absolute value of the difference tends to increase. This is assumed to be because if the measurement interval is too short, fewer time waveforms can be acquired, which weakens the noise reduction effect of averaging.

According to the measurement results shown in FIG. 11, it can be seen that by setting the measurement interval to about 10 [seconds], a suitable number of averaging can be ensured and the absolute value of the difference amount (i.e., temporal fluctuation) can be reduced. Note that the measurement results shown in FIG. 11 are only an example, and the measurement interval is preferably set as appropriate depending on the situation of the target power distribution system 2.

FIG. 12 is a diagram for explaining the process procedure of fault point location in the power distribution system exploration system 1 according to the present embodiment. Referring to FIG. 12, a reference waveform constituting an abnormality determination condition is determined based on measurement results over a predetermined period immediately before an arbitrary event timing (N seconds). As described above, when the measurement interval is set to 10 [seconds], measurement results are repeatedly acquired from about 10 [seconds] before an arbitrary event timing ((1) data accumulation for about 10 seconds). By averaging the repeatedly acquired measurement results, a reference waveform for the target event timing (N seconds) is generated.

Then, a difference waveform between the measurement result (target time waveform) acquired at the target event timing (N seconds) and the reference waveform is calculated ((2) difference waveform from before the accident). It is determined whether the calculated difference waveform satisfies an abnormality determination condition (in this example, the amplitude of the difference waveform is equal to or greater than a predetermined threshold). Then, the distance to the accident point is calculated based on the differential waveform determined to satisfy the abnormality determination condition ((3) distance calculation).

Note that the accident score processing shown in FIG. 12 may be implemented in any form.
For example, if time waveforms are acquired continuously, and an event such as relay detection at a substation occurs, a reference waveform is determined after the fact from the time waveform approximately 10 seconds before the event point, and the reference waveform is determined from the time waveform approximately 10 seconds before the event point. The distance may be calculated.

Alternatively, the reference waveform may be repeatedly determined from a time waveform of about 10 seconds, and it may be determined whether any abnormality has occurred in the time waveform acquired at the timing to be evaluated. Furthermore, even if the distance to the accident point is calculated on the condition that the amplitude of the difference (difference waveform) between the reference waveform and the time waveform acquired at the timing to be evaluated is greater than or equal to a predetermined threshold. good.

In the power distribution system exploration system 1 according to the present embodiment, a reference waveform is determined based on measurement results over a predetermined immediately preceding period, and the difference with respect to the determined reference waveform is used as a temporal feature to detect the power distribution system 2. The presence or absence of any abnormality occurring in the accident and the distance to the accident point are calculated. In this way, the abnormality determination conditions for detecting an abnormality occurring in the power distribution system may be determined depending on the measurement results over a predetermined immediately preceding period. By employing such abnormality determination conditions, the occurrence of an abnormality can be detected more accurately in response to changes in the status of the target power distribution system 2.

<E. Location determination in the event of an accident＞
Next, a processing procedure related to positioning in the measuring device 100 when an accident occurs will be explained.

FIG. 13 is a flowchart showing a processing procedure related to positioning by measuring device 100 according to the present embodiment. Each step shown in FIG. 13 may be executed by the measuring device 100 or the processing device 200 that collects measurement results from the measuring device 100.

Referring to FIG. 13, measurement results (differential waveforms) are collected at predetermined intervals (step S100). It is determined whether an event such as relay detection has occurred at the substation (step S102). If an event such as relay detection has not occurred in the substation (NO in step S102), the processes from step S100 onwards are repeated.

If an event such as relay detection has occurred in the substation (YES in step S102), a reference waveform is determined based on the measurement results (differential waveform) collected in the immediately preceding predetermined period (for example, 10 seconds). (Step S104). A time waveform (difference waveform) of the difference between the measurement result (differential waveform) collected at or after the event occurrence and the reference waveform is calculated (step S106), and the amplitude of the calculated difference waveform is set to a predetermined threshold value. It is determined whether or not it is the above (step S108).

If the amplitude of the calculated differential waveform is greater than or equal to the predetermined threshold (YES in step S108), the distance to the accident point is determined based on the position on the time axis where the amplitude of the differential waveform is greater than or equal to the predetermined threshold. is calculated (step S110).

On the other hand, if the amplitude of the calculated difference waveform is less than the predetermined threshold (NO in step S108), it is determined that the accident has occurred outside the monitoring range of the target measuring device 100 (step S112). In this case, the distance to the accident point is not calculated.

Then, the result of calculation or determination in step S110 or step S112 is output (step S114). Then, the processing from step S100 onwards is repeated.

<F. Abnormality detection through constant monitoring>
As described above, the power distribution system exploration system 1 according to the present embodiment is capable of detecting the occurrence of any kind of accident such as a short circuit, ground fault, or disconnection, as well as detecting a situation that is different from normal (for example, the leakage current is higher than normal). etc.) can be detected. In order to detect such an unusual condition, it is preferable to constantly monitor the target power distribution system 2. By constantly monitoring the target power distribution system 2, it is possible to detect changes in the state that do not lead to accidents, and thereby it is also possible to prevent accidents. Furthermore, even in cases where the accident point disappears after an accident occurs, the accident point can be located.

(f1: Detection of abnormal state)
By constantly monitoring the power distribution system 2, abnormal conditions can be detected and accidents can be prevented from occurring. That is, according to the present embodiment, instead of locating the accident point after some kind of accident occurs, by constantly monitoring, a position where there is some kind of change in state compared to normal times is located.

Specifically, by repeatedly calculating the difference between the collected measurement results (differential waveforms), it is possible to detect an unusual abnormality even if it does not lead to an accident.

FIG. 14 shows an example of measurement results obtained by the measuring device 100 according to the present embodiment in a state where tree contact occurs on the simulated track. Tree contact corresponds to a type of short circuit between lines. Figure 14(A) shows pulses for the simulated track in a steady state (no accident) (healthy) and the simulated track in a state where tree contact has occurred (trees between lines). A time waveform obtained by injecting a wave into the power distribution system 2 is shown. Note that the time waveform shown in FIG. 14(A) is the result of performing averaging processing (averaging processing) 100 times. FIG. 14(B) shows a difference between the two time waveforms shown in FIG. 14(A), a moving average of the difference, and a waveform of a first derivative with respect to the moving average.

Since only an abnormality that did not lead to an accident occurred on the simulated track, information indicating the location where the tree contact occurred appears in the difference between the measurement results (time waveform), but the noise component is also relative. relatively large. Therefore, by calculating the moving average of the time waveform of the difference and using the waveform of the first derivative (the purpose of which is to remove the offset that occurs in the moving average) with respect to the calculated moving average, it is possible to indicate the position where tree contact has occurred. Information can be extracted reliably.

The distance was calculated to be 76.4 [m] based on the measurement results obtained by signal processing of such a differential waveform. Since the actual distance was 72.5 [m], the orientation error was approximately 3.9 [m] (orientation error: approximately 5.8%), indicating that the orientation accuracy was sufficient. .

FIG. 15 shows an example of measurement results obtained by the measuring device 100 according to the present embodiment in a state where an insulator failure has occurred in a simulated line. The presence of a defective insulator corresponds to a type of ground fault or short circuit between wires. Figure 15(A) shows pulse waves for each of the simulated line in a steady state (state in which no accidents have occurred) (healthy) and in a state in which a defective insulator exists on the simulated line (defective insulator). The time waveform obtained by injecting into the power distribution system 2 is shown. Note that the time waveform shown in FIG. 15(A) is the result of performing averaging processing (averaging processing) 100 times. FIG. 15(B) shows a difference between the two time waveforms shown in FIG. 15(A), a moving average of the difference, and a waveform of a first derivative with respect to the moving average.

Since only an abnormality that did not lead to an accident occurred on the simulated track, the difference between the measurement results (time waveform) contains information indicating the location where the insulator defect has occurred, but the noise component is also relative. relatively large. Therefore, by calculating the moving average of the time waveform of the difference and using the waveform of the first derivative (the purpose of which is to remove the offset that occurs in the moving average) with respect to the calculated moving average, it is possible to indicate the position where the insulator defect has occurred. Information can be extracted reliably.

The distance was calculated to be 79.1 [m] based on the measurement results obtained by signal processing of such a differential waveform. Since the actual distance was 67.5 [m], the orientation error was approximately 11.6 [m] (orientation error: approximately 17%), and although the orientation accuracy was somewhat low, it was The accuracy is sufficient for practical use.

FIG. 16 is a flowchart showing a processing procedure for detecting an unusual state by measuring device 100 according to the present embodiment. Each step shown in FIG. 16 may be executed by the measuring device 100 or the processing device 200 that collects measurement results from the measuring device 100.

Referring to FIG. 16, measurement results (differential waveforms) are collected at predetermined intervals (step S200). It is determined whether a predetermined determination cycle has arrived (step S202). If the predetermined determination period has not arrived (NO in step S202), the processes from step S200 onwards are repeated.

If the predetermined determination period has arrived (YES in step S202), a reference waveform is determined based on the measurement results (differential waveform) collected in the previous predetermined period (for example, 10 seconds) (step S204). A time waveform (difference waveform) of the difference between the measurement result (differential waveform) collected at or after the timing of the determination cycle and the reference waveform is calculated (step S206), and a moving average of the calculated difference waveform is calculated. (Step S208). Furthermore, a first derivative of the calculated moving average is calculated (step S210). Then, it is determined whether the amplitude of the calculated first-order differential is greater than or equal to a predetermined threshold (step S212).

If the amplitude of the calculated first derivative is equal to or greater than the predetermined threshold (YES in step S212), it is determined that some kind of abnormality has occurred in the target power distribution system 2 (step S214), and the amplitude of the first derivative is The distance to the point where some abnormality has occurred is calculated based on the position on the time axis where is greater than or equal to a predetermined threshold (step S216).

On the other hand, if the amplitude of the calculated first-order differential is less than the predetermined threshold (NO in step S212), it is determined that the target power distribution system 2 is normal (step S218). In this case, the distance to the accident point is not calculated.

Then, the results of calculation or determination in steps S214 and S216 or step S218 are output (step S220). Then, the processing from step S200 onwards is repeated.

(f2: Orientation of the accident point that disappears after the accident)
By constantly monitoring the power distribution system 2, it is possible to locate the accident point even in the case of an accident that does not result in a permanent accident mode. For example, after some kind of accident occurs, the fault point may disappear due to the fault current. For example, a tree that has caused a short circuit between lines may fall down due to the fault current. In such a case, even if a pulse wave is incident after an accident occurs, no reflected wave is generated, so the accident point cannot be located.

However, during an accident (that is, while a fault current is flowing), a reflected wave of the pulse wave is generated, and the fault point can be located by using the reflected wave. Hereinafter, the location of the fault point using the current flowing during the fault will be explained.

FIG. 17 is a diagram for explaining a simulated track for evaluating fault point location based on fault current flowing during an accident. Referring to FIG. 17, two measuring devices 100 were placed on the simulated track (column No. 22 and No. 24), and a short circuit fault and a ground fault fault were caused to occur on pillar No. 23E2 to measure the fault current. In addition, chicken meat was used as a conductor to imitate birds for short-circuit accidents and ground fault accidents. By using chicken meat as a conductor, it will no longer function as a conductor due to heating caused by the accident current, making it possible to simulate a momentary accident. At this time, fault current flows through pillar No. 22, but no fault current flows through pillar No. 24.

FIG. 18 shows an example of measurement results obtained while a short circuit accident occurs on the simulated line shown in FIG. 17. FIG. 18(A) shows a differential waveform (difference between a steady state and an accident occurring) collected by the measuring device 100 placed on pillar 22 of the simulated track in FIG. 17, and FIG. 18(B) shows shows a differential waveform (difference between a steady state and an accident occurring) collected by the measuring device 100 placed on the No. 24 pillar of the simulated track in FIG. 17.

As shown in FIGS. 18(A) and 18(B), the accident point can be located using the respective measuring devices 100 placed on pillars 22 and 24. According to the difference waveform shown in Figure 18(A), the distance to the accident point is 76.4 [m], and the actual distance to the accident point is 67.5 [m], so the orientation error is 8 .9 [m] (orientation error: approximately 13%). According to the difference waveform shown in FIG. 18(B), the distance to the accident point is 105.9 [m], and the actual distance to the accident point is 92.5 [m], so the orientation error is 13 .4 [m] (orientation error: approximately 14%). Although the orientation error is somewhat large, the accuracy is sufficient for practical use.

In this way, by constantly monitoring, it is possible to capture instantaneous changes during an accident. Furthermore, the fault point can be located both at the location where the fault current flows and at the location where the fault current does not flow.

FIG. 19 shows an example of measurement results obtained during the occurrence of a ground fault accident on the simulated line shown in FIG. 17. FIG. 19(A) shows a differential waveform (difference between a steady state and an accident occurring) collected by the measuring device 100 placed on pillar 22 of the simulated track in FIG. 17, and FIG. 19(B) shows shows a differential waveform (difference between a steady state and an accident occurring) collected by the measuring device 100 placed on the No. 24 pillar of the simulated track in FIG. 17.

As shown in FIGS. 19(A) and 19(B), the accident point can be located using the respective measurement devices 100 placed on pillars 22 and 24. According to the difference waveform shown in Figure 19(A), the distance to the accident point is 76.3 [m], and the actual distance to the accident point is 67.5 [m], so the orientation error is 8 .8 [m] (orientation error: approximately 13%). According to the difference waveform shown in FIG. 19(B), the distance to the accident point is 105.3 [m], and the actual distance to the accident point is 92.5 [m], so the orientation error is 12 .8 [m] (orientation error: approximately 14%). Although the orientation error is somewhat large, the accuracy is sufficient for practical use.

In this way, by constantly monitoring, it is possible to capture instantaneous changes during an accident. Furthermore, the fault point can be located both at the location where the fault current flows and at the location where the fault current does not flow.

In this way, constant monitoring makes it possible to detect temporary accidents such as tree contact and to locate the accident point.

<G. Search for abnormalities in the power distribution system>
In the power distribution system exploration system 1 according to the present embodiment, the occurrence of any abnormality in the power distribution system 2 is detected based on the measurement results 10 by the plurality of measuring devices 100 distributed in the power distribution system 2, and Identify (orient) the location of the abnormality.

In particular, as the line length of the power distribution system 2 becomes longer, the injected pulse waves are attenuated at branch points, etc. Therefore, by distributing the measuring devices 100, comprehensive monitoring of the power distribution system 2 becomes possible.

As described above, the power distribution system exploration system 1 according to the present embodiment is used not only when an accident such as a short circuit, a ground fault, or a disconnection occurs, but also when a situation that is different from normal (for example, the leakage current is higher than normal) is detected. etc.) can be detected. Furthermore, it is also possible to detect accidents in which the cause of the accident disappears and recovery occurs after the accident. By collecting the measurement results 10 collected by each measuring device 100 in the processing device 200, it is possible to detect an accident occurring in the power distribution system 2, a sign of an accident occurring in the power distribution system 2, and the like. It is also possible to identify equipment that is experiencing problems. This makes it possible to repair equipment before an accident that disrupts the power supply occurs.

FIG. 20 is a diagram for explaining an operation example of abnormality exploration in the power distribution system exploration system 1 according to the present embodiment. Referring to FIG. 20, it is assumed that some kind of accident (for example, a ground fault) occurs at a position between measuring device 100-1 and measuring device 100-2. In this case, the fault current will flow from the substation 4 to the fault point, but the fault current will not flow in the wiring section downstream (load side) from the fault point. In the example shown in FIG. 20, the fault current flows in the position where the measuring device 100-1 of the power distribution system 2 is connected, but the fault current flows in the position where the measuring device 100-2 of the power distribution system 2 is connected. Not flowing.

On the other hand, when an event such as relay detection occurs at substation 4, measurement devices 100-1 and 100-2 start measurement. In this measurement, both measuring devices 100-1 and 100-2 can locate the accident point.

The processing device 200 collects the collected time waveforms and/or the rated distance to the accident point as the measurement results from the measurement devices 100-1 and 100-2. Furthermore, the processing device 200 also collects information indicating the presence or absence of fault current in the measurement devices 100-1 and 100-2 as measurement results.

Then, the processing device 200 can identify the fault point in the power distribution system 2 based on the information indicating the presence or absence of fault current in the measurement devices 100-1 and 100-2. In this way, by utilizing the fault current information, it is possible to identify the direction in which an abnormality has occurred. That is, the processing device 200 determines the position where the abnormality has occurred based on the situation when the target measuring device 100 measures the time waveform (for example, the presence or absence of a fault current, the direction in which the fault current flows, etc.).

FIG. 20 shows, as a typical example, a typical configuration in which measurement results from two adjacent measurement devices 100 are used, and an abnormality in the power distribution system 2 is searched based on the measurement results of the two measurement devices 100. As an example, measurement results from more measuring devices 100 may be used to search for the same abnormality.

FIG. 21 is a flowchart showing a processing procedure related to abnormality exploration in the power distribution system exploration system 1 according to the present embodiment. Each step shown in FIG. 21 may be executed by the measuring device 100 or the processing device 200 that collects measurement results from the measuring device 100.

Referring to FIG. 21, the results of abnormality detection for each measuring device 100 included in the power distribution system 2 (presence or absence of an abnormality occurring in the power distribution system 2, and if an abnormality has occurred, whether the abnormality has occurred) are shown. (e.g., distance to a point) are collected (step S300). Note that the abnormality detection results for each measuring device 100 may be obtained by executing abnormality detection processing in each measuring device 100, or by collecting the measurement results 10 from each measuring device 100, The information may be obtained by the processing device 200 executing an abnormality detection process. Further, the abnormality detection process is typically executed by the processing procedure shown in FIGS. 13 and 16 described above.

Then, it is determined whether there is any measuring device 100 in which it has been detected that some kind of abnormality has occurred (step S302). If there is no measuring device 100 in which it has been detected that some kind of abnormality has occurred (NO in step S302), the processes from step S300 onwards are repeated.

If there is a measuring device 100 in which it has been detected that some kind of abnormality has occurred (YES in step S302), a measuring device placed near the measuring device 100 in which it has been detected that some kind of abnormality has occurred is present. The abnormality detection results for 100 are aggregated (step S304). Then, based on the results of abnormality detection for a plurality of measuring devices 100 placed nearby, an abnormality occurring in the power distribution system 2 is identified, and the position where the identified abnormality is occurring is located. (Step S306). In step S306, processing for locating the fault point may be performed based on the presence or absence of abnormal current in each measuring device 100. In this way, when the measurement result from any one of the plurality of measuring devices 100 satisfies a predetermined abnormality determination condition, the processing device 200 detects a The location where the abnormality has occurred in the power distribution system 2 is determined by also referring to the measurement results of other measuring devices 100 located at the location. Note that the abnormality determination conditions include that the amplitude of the differential waveform is equal to or greater than a predetermined threshold value.

Finally, information such as identification of the abnormality and the location where the abnormality is occurring is output (step S308). Then, the processing from step S300 onwards is repeated.

<H. Line selection>
Branch routes may exist in the overhead power distribution system. If such a branch route exists, even if the distance from the measuring device 100 to the accident point can be calculated, it may not be possible to specify which branch route the accident point is on. In other words, there are multiple candidates that can become the accident point. Therefore, if necessary, by arranging a ferrite core for the branch path, a branch path in which an incident wave (pulse wave) and a reflected wave occur may be selected. This utilizes the function of restricting the transmission of pulse waves in branch paths in which ferrite cores are arranged. Regarding the branch path in which the ferrite core is arranged, the input impedance or transmission coefficient/reflection coefficient as seen from the incident side changes. Such an effect may be utilized to select a target for locating the accident point.

The pulse wave blocking performance of such a ferrite core will be explained.
FIG. 22 is a diagram showing an example of a simulated line for evaluating the interrupting performance of the ferrite core in the power distribution system exploration system 1 according to the present embodiment. Referring to FIG. 22, a pulse wave is input and the time waveform appearing in the power distribution system 2 is measured for a state in which a ferrite core is not arranged in a branch route included in a simulated line and a state in which a ferrite core is arranged.

FIG. 23 shows an example of a time waveform measured on the simulated line shown in FIG. 22. Figure 23 shows the time waveform measured with no ferrite core placed in the branch route (without ferrite core) and the time waveform measured with a ferrite core placed in the branch route (with ferrite core). are shown on the same time axis.

As shown in FIG. 23, the time waveform measured with the ferrite core placed in the branch path is significantly different from the time waveform measured with the ferrite core not placed in the branch path. It can be seen that the reflected components from the 23E1 column and the 23E2 column existing on the arranged branch route are suppressed.

According to the time waveform shown in FIG. 23, by arranging the ferrite core on the branch route, it is possible to reduce the intrusion of pulse waves into the branch route where the ferrite core is arranged, and to exclude it from the exploration target. That is, in the case where the power distribution system 2 includes a plurality of branch routes, the branch route in which no ferrite core is disposed becomes the search target.

In this way, a ferrite core is placed in one of the branch paths included in the power distribution system 2 and guides a pulse wave (incident wave) from one of the measuring devices 100 to a specific path among the branch paths. Good too. In this case, the processing device 200 determines the position of an abnormality that may occur in the power distribution system 2 according to the arrangement position of the ferrite core.

Furthermore, a configuration may be adopted in which the ferrite core is automatically placed or removed. By adopting such a configuration, the exploration range can be controlled arbitrarily in the event of an accident or when determining the presence or absence of an abnormality.

<I. Advantages＞
According to the power distribution system exploration system 1 according to the present embodiment, it is possible to detect any abnormality occurring in the power distribution system 2 using the measurement results 10 obtained by the plurality of measuring devices 100 distributed within the power distribution system 2, and The location where the abnormality occurs can be identified.

According to the power distribution system exploration system 1 according to the present embodiment, in addition to a state in which some kind of accident such as a short circuit, a ground fault, or a disconnection that may occur in the power distribution system 2 has occurred, an unusual state (for example, a leakage current (e.g., more than normal) can be detected.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

1 Power distribution system exploration system, 2 Power distribution system, 4 Substation, 10 Measurement results, 100 Measurement device, 102 Pulse transformer board, 104 Coaxial cable, 106 Main control section, 110 Measurement section, 112 Pulse generator, 114 A/D conversion 116 arithmetic unit, 118 communication unit, 120, 130 amplifier, 122, 132 directional coupler, 140 coupling unit, 142 coupling circuit, 144 high voltage capacitor, 200 processing device.

Claims (4)

A power distribution system exploration system for exploring abnormalities occurring in a power distribution system including at least an overhead wiring section,
a plurality of measuring devices arranged at different positions in the power distribution system;
and a processing device that processes each measurement result obtained by the plurality of measurement devices,
Each of the plurality of measuring devices includes:
a pulse generator that generates pulses;
a detection unit that injects the pulse generated by the pulse generation unit into two phases included in the power distribution system and outputs a potential difference appearing between the two injected phases;
The processing device includes:
For each of the plurality of measuring devices, at periodically arriving judgment timings, a reference waveform, which is a waveform of a potential difference collected in a predetermined period immediately before the judgment timing, and a reference waveform that is a waveform of a potential difference collected at or after the judgment timing. It is determined whether or not an abnormality has occurred based on a differential waveform that is the difference between a differential waveform that is a waveform of a potential difference, and when it is determined that an abnormality has occurred, an abnormality is detected based on the differential waveform. Calculate the distance to the point where the
When it is determined that an abnormality has occurred in any one of the plurality of measuring devices, the measurement device in which it has been determined that the abnormality has occurred and at least another measurement device adjacent to the said measuring device determining the position where the abnormality has occurred in the power distribution system based on the determination result of whether or not an abnormality has occurred with respect to the device and the calculated distance to the point where the abnormality has occurred; Systematic exploration system. The power distribution system exploration system according to claim 1, wherein the pulse generator is configured to inject the pulse into the power distribution system via capacitive coupling. Each of the plurality of measurement devices is disposed between the pulse generator and the power distribution system, and guides the pulse from the pulse generator to the power distribution system, and conducts the pulse from the power distribution system in response to the pulse from the power distribution system. The power distribution system exploration system according to claim 1 or 2, further comprising a directional coupler that guides reflected waves to the detection section. Further comprising a ferrite core disposed on any of the branch paths included in the power distribution system and guiding an incident wave from any of the measurement devices to a specific path among the branch paths,
The power distribution system exploration system according to any one of claims 1 to 3, wherein the processing device determines the position of an abnormality that may occur in the power distribution system, depending on the arrangement position of the ferrite core.

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