JP6624165B2 - Distribution line fault location system - Google Patents

Description

  The present invention relates to a distribution line fault point locating system, and more specifically, a surge current waveform for recording a surge current waveform at the time of an electrical accident such as a ground fault or a short circuit in a distribution transmission line from a distribution substation to a terminal customer. The present invention relates to a recording apparatus, a surge electric field waveform recording apparatus for recording a surge electric field waveform, and a distribution line failure point locating system configured from the recorded waveforms and a distribution line failure point locating apparatus for estimating an occurrence position of an electric accident.

  In the case of ungrounded distribution lines, the neutral point is not grounded, so even if there is a ground fault, the ground fault current is small, so-called effective value type fault point locating device based on the effective value of voltage and current viewed from the transmitting end or receiving end, It has been difficult to locate a fault using an impedance-type fault location device based on the impedance to the fault calculated from the voltage and current values measured in the accident phase.

  For this reason, a current sensor (CT) / voltage sensor (VT) or an electric field sensor / electromagnetic field sensor is installed on a steel tower or pole to record the surge current (or voltage) waveform at the time of a system accident, and to transfer between the observation points. In many cases, a failure point is located based on the arrival time difference (Patent Documents 1 and 2). In addition, there is a method of observing and recording the effective value of the ground voltage of an accident phase at an accident at a plurality of points at the time of an accident, and using the fact that the value decreases toward a failure point to locate a failure point (Patent Document 3).

  Patent Document 1 describes the use of zero-phase voltage and zero-phase current surge waveform data for fault location in Document No. [0007] and the like. Patent Document 2 describes the zero-sequence voltage in Document No. [0007] and the like. Is described.

  These measures the current signal waveform or voltage signal waveform of the transmission line for each phase, synthesizes a zero-phase waveform from the voltage waveform on the secondary side of the converter, and uses the waveform data to determine the surge waveform generated during the accident. Is detected, and a failure point is obtained from the arrival time difference of the surge waveform portion. However, installing a sensor for each phase is disadvantageous in terms of cost of the sensor itself and construction costs.

  In the case of transmission lines of 22 kV to 33 kV systems, which are generally referred to as lower systems, the ratio of the cost required for such monitoring equipment is larger than the profits obtained therefrom. The demand for cost reduction is increasing. In particular, the lower the distribution line, the more branches there are, and it is desirable that only one sensor and one waveform recorder be installed at the end of each branch transmission line so that fault points can be located.

  Patent Document 5 describes a method of calculating a fault point from a difference in arrival time of a surge when a transmission line is composed of a main line and a branch line, and a failure point in the case of a single transmission line (including a branch). Positioning can in most cases be performed in this way.

  By the way, in a non-grounded system, even if the distribution line has a load current of about 100 A, the current at the time of ground fault is about 1 to 2 A, and if the error of the current transformer (also called a current sensor or CT) is about 1%, The ground fault current value is often buried in an error and difficult to recognize.

In the case of an ungrounded system, the ground fault current flows due to the capacitance between the transmission line and the ground.Therefore, while the current is maximum at the ground fault point, the value of the ground fault current decreases toward the transmission end or load end. , At the very end, it is zero. This is the same not only in the waveform of the commercial frequency but also in the surge current waveform. At the terminal having a high impedance to the ground, the ground fault current hardly flows. Therefore, it is necessary to always measure the ground fault current in the middle of the power transmission section (Fig. 1 of Patent Document 1). When the fault point is located based on the arrival time difference of the current surge waveform, the distance from the current sensor to the end of the transmission line is required. No section could be located.

On the other hand, at the end, the zero-phase voltage value becomes maximum. This is evident from the fact that the increments due to [voltage per unit length] (= [impedance per unit length] x [ground fault current value]) accumulate in each part of the transmission line, and that they increase at the end. is there.

  Here, the term “terminal” refers to the power receiving end. The transmission end is the substation bus, which is usually connected to multiple distribution lines, and the surge current generated in one distribution line is connected to the other distribution line via the substation bus. Flow into Therefore, the bus is merely a relay point as a destination of the surge current generated at the ground fault point.

By the way, the surge waveform is often observed with its rising rising affected by the characteristics of the cable from the sensor to the waveform recording device. Sensors, cables, and waveform recorders of exactly the same standard have the same accent, so it is easy to compare.For example, if one is a surge voltage waveform at the time of ground fault and the other is a surge current waveform, generally Is fundamentally different because the voltage sensor at both ends of the transmission line recognizes a surge current waveform generated at the fault point during propagation on the line as a voltage surge waveform.
A waveform with a steep rise is good, but a waveform with a gentle rise changes the threshold of the determination level for determining that there is a surge, so that the detection time also changes, which is an error factor. Therefore, when locating a fault using the arrival time difference of the surge waveform, it is desirable to compare the arrival time difference of the surge waveform between current waveforms or voltage waveforms as much as possible.

Patent No. 3689078 Patent No. 4919592 Patent No. 5161930 Patent No. 4790050 Japanese Patent No. 4444489

  In view of these points, the problem to be solved by the present application is to use for fault detection and fault location even in ungrounded transmission lines where the fault current is about several percent or less of the load current. Fault detection and location, even at the end of the distribution transmission line where almost no ground fault current flows at the time of ground fault, and fault location for distribution lines that can achieve fault location with fewer sensors than existing equipment It is to provide a system.

  The inventor of the present application initially installed a surge current sensor in each phase of each line connected to the bus of the distribution substation, and installed a surge voltage sensor in each phase at the terminal receiving end, but a large number of From the results of data collection, we noticed that the surge waveform arrived at exactly the same timing in all phases during a short circuit and ground fault. This indicates that it is useless to collect data for all three phases in performing the fault point localization based on the surge arrival time difference, and that only one phase is sufficient. It was also found that a voltage surge rather than a current surge should be observed because a ground fault current does not flow at the end of the transmission line even if a ground fault occurs.

  The inventor of the present application has noticed that there is no problem in measuring the surge arrival timing even if one surge sensor is normally installed for each phase for each three-phase circuit. They decided to use one sensor per three-phase one-circuit.

  This non-contact type electric field sensor can detect a voltage waveform obtained by dividing a voltage applied between the transmission line and the ground by the capacitance between the transmission line and the ground. Thus, in the case of a ground fault, the surge voltage waveform between the transmission line and the ground can be observed.

On the other hand, in the case of a two-wire short-circuit fault, although fault currents of substantially the same magnitude flow in two of the three phases, they are in opposite phases, so that electric field vectors generated in the surroundings cancel each other out, making detection difficult. Therefore, the inventor of the present application has changed a surge electric field detector (hereinafter referred to as a surge electric field detector or a surge electric field detection antenna or simply an antenna) [FIG. By arranging them so as to be at different distances from the three-phase transmission line, it is considered that a surge voltage waveform having a sufficient amplitude that can be detected even in the event of a short circuit can be detected.

  By the way, the surge voltage waveform may be generated in the case of a phenomenon called so-called induced lightning that strikes near the transmission line, or after the secondary side of the transformer connected to the receiving end at the end (called the load end). It is also observed when a sudden load change (such as turning on the power of a large consumer factory) occurs.

  Therefore, in the present application, in the distribution substation on the power transmission side, a current sensor is arranged in each phase of each transmission line connected to the bus, where the AC current waveform is constantly monitored to determine whether there is an accident. When an accident is detected, the time data for extracting the surge waveform immediately before the accident is recorded, and the surge waveform detected by the electric field sensor at the end of the transmission line using the data is the actual or non-accident noise. I'm judging what it is.

By the way, in Patent Document 1, as described in the sentence number [0020] of the specification, not only a voltage sensor but also a current sensor is attached to the end of a transmission line to detect an accident. However, in the case of a non-grounded system, the ground receiving terminal is not grounded at the terminal receiving end, so that even if a ground fault occurs on the transmission line on the way, the ground-to-ground current (hereinafter referred to as zero-phase current) hardly flows, so it is sufficient. It is difficult to obtain amplitude waveform data. Therefore, the inventor of the present application has arranged only the non-contact type electric field sensor at the end of the transmission line.

  On the other hand, in the case of a short circuit fault with only one electric field sensor on the line, the fault surge waveform detected by the electric field sensor may be small because fault currents flowing between the two phases cancel each other. In fact, it is not possible to completely cancel each other due to the slight asymmetry of the circuit, and it is impossible to detect a surge waveform with an electric field sensor at all in the event of a short circuit because a large fault current flows compared to a ground fault fault. However, in the present application, it is possible in principle to observe a sufficient amplitude of the surge waveform by arranging the position of the sensor at a different distance between any two phases. This is the feature of the first invention of the present application.

  By the way, in the current data at the substation end on the transmission side, the waveform data of the commercial frequency component and the surge component can be obtained with sufficient amplitude despite the ground fault of the ungrounded system. This is because the distribution substation is not observed at the distribution line side but at the other end of the transmission line connected to the same bus instead of at the end, and the ground fault current component flows into the transmission line and is observed as a current waveform. is there.

  In this way, the inventor of the present application arranges one current sensor for each phase of each line at the power transmission end and one non-contact electric field sensor for each line at the power reception end, so that in a non-grounded system, We constructed a system that can efficiently and reliably locate a fault point with fewer sensors.

  The surge electric field waveform recording device having these features is a surge electric field detection antenna, a high impedance input amplifier receiving an output of the surge electric field detection antenna, and extracting a surge component by receiving an output of the high impedance input amplifier. A band-pass filter having a frequency band of about 100 kHz to several MHz, a high-speed sampling A / D converter for receiving the output of the band-pass filter and A / D converting the output at a sampling frequency of about several MHz; A pre-trigger memory that stores the converted surge electric field instantaneous value data for a fixed number of samples, a trigger detection unit that detects that the absolute value of the surge electric field instantaneous value data exceeds a separately set value, and at the time of the detection. Storing the surge electric field instantaneous value data in the pre-trigger memory for a predetermined time. A main memory, a transmission unit for outputting data of the main in-memory data communication antenna, consisting of the data communication antenna.

  On the other hand, the surge current waveform recording device includes a current transformer installed for each phase of the transmission line on the power transmission end side, a shunt resistor on the transformer secondary side, and an input amplifier for receiving a voltage waveform across the shunt resistor. A band-pass filter having a frequency band of about 100 kHz to several MHz receiving the output of the amplifier and extracting a surge component, and receiving the output of the band-pass filter and performing A / D conversion at a sampling frequency of about several MHz. High-speed sampling A / D converter, a pre-trigger memory for storing A / D-converted instantaneous surge current data for a fixed number of samples, and an absolute value of the surge current instantaneous value data exceeding a separately set value. A trigger detection unit for detecting that the surge current has occurred, and a main memory for storing the surge current instantaneous value data in the pre-trigger memory for a predetermined time at the time of the detection. And Lee, a transmission unit for outputting the main data in memory in a data communication antenna, consisting of the data communication antenna.

  On the other hand, the fault point locating device is a personal computer or a server device having an arithmetic function, is connected to a communication line, receives the waveform data output by the surge electric field waveform recording device and the surge current waveform recording device, and generates a fault. Performs point location calculations and displays or saves the results. The system constituted by such a device is a feature of the second invention of the present application.

In this fault point location calculation, the time of the rising (or falling) point of the waveform in each of the surge electric field waveform data and the surge current waveform data is T1 [sec] and T2 [sec], and the surge propagation speed is ν. [km / sec], and assuming that the line length from the transmitting end to the terminal is L [km], the distance λ [km] from the transmitting end to the surge occurrence point is λ = {L + ν · (T2−T1)} / 2. It is characterized in that it is calculated. This is a feature of the third invention of the present application.

On the other hand, although the presence of a ground fault has been detected by the surge current waveform data, the rising (or falling) point of the surge current waveform cannot often be clearly detected. In the case of an ungrounded transmission line, even if a ground fault occurs, the ground fault current is often about several percent of the load current, and the rise time of the waveform may be buried in the noise of the load current, making it difficult to detect. It is.

In such a case, the rise of the surge electric field waveform obtained from the second surge electric field detector installed at the end of another branch transmission line (also referred to as a feeder) connected to the same bus of the substation The time at the (or falling) point is T2 [sec], the propagation speed of the surge is ν [km / sec], and the total line length between the two surge electric field detectors is L [km]. It is a feature of the fourth invention that the distance λ [km] along the transmission line from the electric field detector installation point to the surge occurrence point is calculated as λ = {L + ν · (T2−T1)} / 2.

  According to the present invention, three current sensors are required at least at two places of a non-grounded transmission line in the prior art for locating a failure point. However, three current sensors are provided at a transmitting end and a non-contact electric field sensor 1 is provided at a receiving end. It is necessary to use only one piece, which is advantageous in terms of cost. Further, even when the value of the ground fault current is too small at the power transmission end of the non-grounding system to detect the rise time, the failure point can be located by the difference in the arrival time of the surge waveform between the electric field sensors at the power reception end.

In the case of an ungrounded system, since a ground fault current does not flow to the terminal in the first place, there is no point in installing the current sensor near the terminal, and therefore the section where the fault point can be located was limited, but the method of the present application Can be located over the entire section of the ungrounded transmission line.
Further, in the case of a short-circuit accident as well as a ground-fault accident, it is possible to detect an accident and locate a fault point with exactly the same device configuration.

Conceptual diagram of power transmission line circuit and overall system Figure of installation example of surge electric field waveform recorder and surge electric field detection antenna Figure of [Figure 2] looking down from above (top view) Illustration of antenna position 1 Illustration of antenna position 2 In FIG. 4-1, an example of an antenna voltage waveform at the time of a short circuit accident between two phases A and B of two transmission lines equidistant from the antenna. Example of antenna voltage waveform at the time of short circuit accident between two transmission lines A phase and B phase not equidistant from antenna as shown in [Fig. 4-2] Block diagram of surge electric field waveform recorder Block diagram of surge current waveform recorder System model and application system (in case of 2 feeders)

  Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a conceptual diagram showing the entire system of the present application. A CT sensor 5 is attached to each phase of the distribution transmission line 4 connected to the bus 3 of the distribution substation, and a surge electric field waveform recording device is installed at an end of the distribution transmission line 4. When an accident occurs, the accident surge current waveform and accident surge electric field waveform are picked up by the CT sensor connected to the current surge waveform recorder and the electric field detection antenna connected to the surge electric field waveform recorder, and saved as data by the respective waveform recorders. Is done. The current surge waveform recorder has a function of adding a waveform recording function of a data sampling frequency of about 10 MHz in the automatic oscillograph of Patent Document 4.

  On the other hand, the surge electric field detection antenna and the surge electric field waveform recording device are directly attached to a power transmission tower or a distribution line, and their appearance is as shown in FIG.

  FIG. 3 is a view of the apparatus of the present invention attached to a power pole of a distribution line, as viewed from above.

This surge electric field waveform recording apparatus has a high impedance input amplifier 43, a band pass filter 44, a high-speed sampling A / D converter 45, a trigger detection unit 50, a pre-trigger memory 46 as shown in the block diagram of FIG. The signal from the electric field detecting antenna 42 on the power receiving end side is amplified by a high impedance input amplifier 43 and converted to a low impedance output, and then further 100 kHz to several MHz. A surge waveform component is extracted by using a band-pass filter 44 having a frequency band of the order, and A / D conversion is performed by a high-speed sampling A / D converter 45 (sampling frequency of about 10 MHz) to extract electric field surge waveform data. Are transferred to the pre-trigger memory 46. The transfer is always performed while overwriting the memory, and when the absolute value of the instantaneous value exceeds a separately set value, the electric field surge waveform data for a certain time is transferred to the main memory 47 through the memory 46 before the trigger. It is stored and sent to the server through the transmission unit 48 and the data communication antenna 49.
Although not shown in FIG. 6-1 because it is not the scope of the patent application of the present application, a GPS time synchronization unit for obtaining an accurate sampling time and a power supply unit for obtaining electric energy from a solar panel are also provided. Actually implemented.

  The surge current waveform recording device 10 of FIG. 1 includes an input amplifier 54, a band-pass filter 55, a high-speed sampling A / D converter 56, and a trigger detection unit 61, as shown in the block diagram of FIG. , A pre-trigger memory 57, a main memory 58, a transmission unit 59, etc., and signals from a shunt resistor 53 connected between a current transformer 51 installed on a transmission line 52 on the power transmission end side and its secondary output are After the power is amplified by the input amplifier 54, a surge waveform component is further extracted using a band-pass filter 55 having a frequency band of about 100 kHz to several MHz, and a high-speed sampling A / D converter 56 (sampling frequency of about 10 MHz). A / D conversion extracts current surge waveform data including commercial frequency components, and transfers the data to pre-trigger memory 57. That. The transfer is always performed while overwriting the memory, and when the absolute value of the instantaneous value exceeds a separately set value, current surge waveform data for a certain time is transferred to the main memory 58 through the memory 57 before the trigger. It is stored and sent to the server through the transmission unit 59 and the data communication antenna 60.

  The band-pass filter 55 extracts only a surge component, but also passes a commercial frequency component using a low-pass filter instead of the band-pass filter, and detects the presence or absence of an accidental current component in the commercial frequency component. Alternatively, it may be determined whether the obtained data is an accident or a simple noise. Further, completely different hardware for detecting and recording the commercial frequency component may be provided before the bandpass filter.

  [FIG. 7] shows an example in which two transmission lines are connected to a bus of a distribution substation.

During actual operation, a current surge waveform recorder 78 is provided at the transmission end of each transmission line branching from the substation bus as shown in FIG. 7 and a surge electric field waveform is recorded at the end of each of the distribution transmission lines 66 and 73. The devices 71 and 72 are installed to record current surge waveform data at the transmission end of the distribution line and surge electric field waveform data at the end of the distribution line.

  The recorded current surge waveform data and surge electric field waveform data are transmitted to the server device 15 through the network 14 as shown in FIG. On the other hand, a surge current waveform recording device for recording the surge current waveform is installed in the substation, and the AC waveform of the commercial frequency is extracted from this device, and the recorded surge waveform is simply noise or actual noise. Judgment is part of the accident waveform.

1 Transmission end
2 Power receiving end
3 Distribution substation bus
4 Power transmission lines
5 CT sensor
6 Accident points
7 Surge electric field detection antenna
8 Data communication antenna
9 Data communication antenna
10 Surge current waveform recorder
11 Surge electric field waveform recorder
12 pole transformer
13 network base stations
14 Network
15 servers
16 client computers
17 Surge electric field detection antenna
18 telephone pole
19 Surge electric field waveform recorder
20 Arms
21 Surge electric field detection antenna
22 Transmission line
23 Surge electric field waveform recorder
24 insulator
25 telephone pole mounting band
26 telephone pole
27 C phase transmission line
28 B phase transmission line
29 A phase transmission line
30 insulator
31 arm
32 Surge electric field detection antenna
33 telephone pole
34 C phase transmission line
35 B phase transmission line
36 A phase transmission line
37 insulator
38 Arms
39 Surge electric field detection antenna
40 telephone pole
41 Surge electric field waveform recorder
42 Surge electric field detection antenna
43 High impedance input amplifier
44 Band Pass Filter
45 High-speed sampling A / D converter
46 pre-trigger memory
47 main memory
48 Transmission section
49 Data Communication Antenna
50 Trigger detector
51 Current transformer
52 Transmission line
53 Shunt resistor
54 input amplifier
55 bandpass filter
56 High-speed sampling A / D converter
57 Pre-trigger memory
58 main memory
59 Transmission section
60 Data communication antenna
61 Trigger detector
62 Surge current waveform recorder
63 Transmission end
64 Power receiving end 1
65 Distribution Substation Bus
66 Distribution line 1
67 CT sensor 1
68 Accident point
69 Surge electric field detection antenna 1
70 Data Communication Antenna 1
71 Surge electric field waveform recorder 1
72 Power receiving end 2
73 Power Transmission Line 2
74 CT sensor 2
75 Surge electric field detection antenna 2
76 Data Communication Antenna 2
77 Surge electric field waveform recorder 2
78 Surge current waveform recorder
79 Data Communication Antenna

Claims (2)

A surge electric field waveform recording device, a surge current waveform recording device, and a distribution line failure point location system including a failure point location device,
The surge electric field waveform recording device includes a surge electric field detection antenna , a high impedance input amplifier receiving an output of the surge electric field detection antenna, and a surge component of about 100 kHz to several MHz receiving an output of the high impedance input amplifier. A high-speed sampling A / D converter that receives the output of the band-pass filter and A / D-converts it at a sampling frequency of about several MHz or more, The pre-trigger memory that stores the surge electric field instantaneous value data for a fixed number of samples, and when the absolute value of the surge electric field instantaneous value data exceeds a separately set value, the surge electric field instantaneous value data in the pre-trigger memory. Main memory for storing for a certain period of time and data in the main memory Consists of a transmission unit that,
On the other hand, the surge current waveform recording device receives a current transformer installed for each phase of the transmission line on the transmission end side, a shunt resistor on the secondary side of the current transformer, and a voltage waveform at both ends of the shunt resistor. A band-pass filter having a frequency band of about 100 kHz to several MHz, a high-speed sampling A / D converter for receiving the output of the band-pass filter and performing A / D conversion at a sampling frequency of about several MHz; A pre-trigger memory for storing the A / D-converted surge current instantaneous value data for a fixed number of samples, and a memory in the pre-trigger memory when the absolute value of the surge current instantaneous value data exceeds a separately set value. A main memory that stores the surge current instantaneous value data for a certain period of time, and a transmission unit that outputs data in the main memory to a communication line;
On the other hand, the fault point locating device is a device having an arithmetic function, is connected to a communication line, receives the waveform data output by the surge electric field waveform recording device and the surge current waveform recording device, and performs fault locating. It is characterized by doing
The distribution line fault point locating system is characterized in that in a distribution line of an ungrounded system, one set of the surge electric field waveform recording device is provided at one end of a power receiving end of the terminal, and the surge electric field waveform recording device is provided. Uses the antenna for detecting the surge electric field which is parallel to each phase of the transmission line and is not in contact with a space, as a sensor, and the antenna for detecting the surge electric field is installed on a plane parallel to the line of each phase of the transmission line. It is characterized by one metal plate or several metal rods electrically connected, and installed in a position where the capacitance between any two of the transmission lines of each phase is not equal A distribution line fault point locating system, characterized in that:
2. The distribution line fault point locating system according to claim 1, wherein the rising or falling time of each of the surge electric field waveform data and the surge current waveform data is T1 and T2, and the surge propagation speed is ν [ km / s], and when the line length from the transmitting end to the end is L [m], the distance λ from the transmitting end to the surge occurrence point is calculated as λ = {L + ν · (T2−T1)} / 2. A distribution line fault point location system characterized by :
If the value of the ground fault current at the ungrounded power transmission end is too small to detect the rise time, it is obtained from the second surge electric field detector installed at the end of another branch transmission line connected to the power transmission end. The time of the rising or falling point of the surge electric field waveform obtained is T2 [sec], and the total line length between the two surge electric field detectors is L [km] from the second surge electric field detector installation point. A distribution line fault point locating system, wherein a distance λ [km] along a transmission line to a surge occurrence point is calculated as λ = {L + ν · (T2−T1)} / 2 .