JPH03237372A - Method and device for searching abnormal position of overhead transmission line and equipment thereof - Google Patents

Abstract

PURPOSE:To distinctly search an abnormality by measuring the distance to an overhead transmission line and equipments thereof by a distance measuring device while receiving a radio wave emitted from the aforementioned overhead trasmission line and equipments thereof by a measuring antenna. CONSTITUTION:A helicopter loaded with the device as shown in the figure is made to fly at a speed as constant as possible along the overhead transmission line for which the search of abnormality is going to be performed, and the radio waves from the overhead transmission line and equipments thereof are measured by the measuring antenna 10 while measuring the distance between the helicopter and overhead transmission line by a radio wave distance meter 12. The data of measuring radio wave corrected for distance by a distance correcting circuit 30 are supplied to a high speed Fourier transform circuit (FFT) 34 and an outbreaking wave detection circuit 36 through a buffer memory 32. When a corrosion or stain on the element wire of overhead transmission line exists at this time, a noise level becomes larger according to that degrees. If there exists the disconnection of element wire, a sharp outbreaking wave is generated and the width of outbreaking wave is varied according to that scale.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method and device for detecting abnormalities in overhead power transmission lines (including sleeves, spacers, and dampers) and their equipment (steel towers, insulators, etc.), and more particularly to Specifically, the present invention relates to a method and apparatus for detecting abnormalities in overhead power transmission lines and their equipment using corona discharge.

[Prior art] A method and device for detecting abnormalities in overhead power transmission lines and their equipment by corona discharge is disclosed in Patent Application Publication No. 5 in 1988.
No. 03324 (PCT/CH36100066). The method disclosed in this publication involves flying a helicopter along an aerial overhead wire, receiving radio waves in the band of 20MHz to 2QOMHz using an antenna for detecting corona discharge mounted on the helicopter, and recording the waveform on an oscilloscope (the same publication). 5 to 9) to determine and detect the defective location.

[Problem to be solved by the invention] However, in the above conventional example, the measurement frequency band is mainly 20MHz.
z to 200 MHz, which is extremely high, and therefore high-speed and expensive circuit elements must be used in each part.

In addition, in the above conventional example, the existence and content of an abnormality are determined from the disturbance of the waveform of the oscilloscope, but the corona signal is several liters of
Since it occurs at a speed of μS, in this determination method,
It is difficult to quantitatively and objectively determine the content of the abnormality. Since the judgment is made by human eyes, there are individual differences, day-to-day, and time-of-day differences, making it inaccurate. It is also difficult to pinpoint the location of the abnormality. For example, if a part of the wire of an overhead power transmission line is broken near the insulator part of a transmission line tower, it is difficult to determine and identify whether the abnormality is the insulator or the overhead power transmission line.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and provide a method and apparatus that can clearly detect abnormalities in overhead power transmission lines and their equipment.

[Means for Solving the Problems] In the exploration method according to the present invention, first, while moving along the overhead power transmission line to be explored, a measurement antenna is used to receive radio waves emitted from the overhead power transmission line and its equipment. , the distance to the overhead power transmission line and its equipment is measured using a distance measuring device. The radio signal thus measured is then divided into predetermined low frequency bands and analyzed. Furthermore, before this analysis, it is preferable to perform distance correction on the measured radio signal based on the measured distance.

The exploration device according to the present invention includes a measurement antenna that receives radio waves from overhead power transmission lines and their equipment, a distance measuring means that measures the distance to the overhead power transmission lines and their equipment to be surveyed, and a method for determining the location of steel towers and the like. a position information input means for inputting position information of an object that is located, and a record for recording on a recording medium the radio wave signal received by the measurement antenna, the distance signal from the distance measurement means, and the position information input by the position information input means; The means is mounted on a projectile and is flown along an overhead power line for exploration purposes. In addition, a reproduction means for reproducing the signal recorded on the recording medium, a distance correction means for correcting the distance of the radio wave signal reproduced by the reproduction means using the reproduced distance signal, and a distance correction means for correcting the distance by the distance correction means. The frequency dividing means divides the radio wave signal into predetermined frequency bands in a low frequency band, and the output means outputs an image of the signal in the frequency band divided by the frequency dividing means.

[Function] Since the existence and content of an abnormality can be determined using low-frequency radio waves, each process can be realized by a low-speed circuit or a digital data processing circuit with program operation, and therefore, anomalies can be detected at a very low cost. . Further, by performing distance correction, it is no longer necessary to keep the distance to the overhead power line precisely constant during measurement, and data collection becomes easier. This also helps reduce costs.

Since individual abnormalities appear as symptoms specific to a specific frequency band or a wide frequency band of the measured radio waves, it becomes possible to accurately determine the content and location of the abnormality.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

Although a certain amount of corona discharge normally occurs in overhead power transmission lines and their equipment, localized abnormal corona discharge may occur due to defects or abnormalities such as corrosion, dirt, or breakage of the wires. , Radio waves are radiated to the surroundings by the radio waves and propagating power caused by this abnormal corona discharge. Through several experiments conducted by the inventor, it has been found that the above defects or abnormalities can be detected using relatively low frequency radio waves (up to about 10 KH2 at most) from overhead power transmission lines and their equipment. Further, the frequency of radio waves caused by electric power propagating through overhead power transmission lines matches the frequency of the electric power (50 Hz or 60 Hz, hereinafter referred to as fundamental wave), and the amplitude thereof is generally proportional to the propagating electric power. As a result of observation, it was found that the amplitude of radiated radio waves due to propagating power is affected by grounding failure of the steel tower. Therefore, it has been found that it is possible to determine the presence or absence of a malfunction in a steel tower and its degree from the amplitude of the fundamental wave acid component of radio waves from overhead power transmission lines and their equipment.

FIGS. 1A and 1B show schematic block diagrams of an embodiment of the present invention. FIG. 1A shows equipment mounted on a helicopter. In FIG. 1A, 10 is a measurement antenna that receives the radio waves radiated from overhead power transmission lines and their equipment. In this embodiment, the measurement antenna 10 has 50 to 6
Any antenna that can receive radio waves from the fundamental wave of 0 Hz to about 10 KHz at most may be used.

12 is a radio distance meter that measures the distance to the measurement target (overhead power transmission line and its equipment) using a radio wave method.

In this embodiment, a rangefinder JRA-100 manufactured by Japan Aviation Electronics Industry, Ltd. was used as the radio rangefinder 12. This rangefinder JRA-100 has a transmission frequency of 4.3GHz.
The distance to the object is measured by emitting pulsed radio waves to the object and measuring the time it takes to receive the reflected radio waves from the object. This distance meter JRA-100 can measure distance with an accuracy of ±2 feet within the distance range targeted by this embodiment.

A position and ground speed meter 14 measures the position and ground speed of the helicopter, and uses, for example, the well-known GPS (Global Positioning System). Reference numeral 16 denotes a position fixed marker that generates a fixed mark signal for a fixed point whose ground position is known (for example, a steel tower supporting an overhead power transmission line, a sleeve, a spacer, a damper, etc.). The position fixing marker 16 is arranged so that the plurality of fixed points can be distinguished later.
It includes a plurality of switches that individually generate different voltages. The fixed position marker 16 facilitates confirmation of the ground position when analyzing measurement data.

Based on the output of the ground speed meter 14 and fixed position marker 16,
The flight position, that is, the measurement position can be accurately known.

18 is a measurement antenna 10. This is an interface circuit that converts signals from the radio distance meter 12, ground speed meter 14, and fixed position marker 16 in order to record them on the data recorder 20. In the interface circuit 18, 92 is an amplifier that amplifies the weak radio waves received by the measurement antenna 10 to the input voltage range of the data recorder 20, 94 is an amplifier that amplifies the output voltage of the radio distance meter 12,
96 is an amplifier that amplifies the output of the ground speed meter 14; 98 is a low-pass filter (LPF) that extracts the low frequency component of the output of the amplifier 92; 100 is a voltage pulse corresponding to the button number of the constant marker 16; This is a pulse generation circuit that generates signals.

The data recorder 20 is, for example, a digital audio tape recorder that includes a plurality of recording channels and digitally records the measurement signals and output data of each of the above-mentioned elements on a magnetic tape 22.

A helicopter equipped with the equipment shown in FIG. 1A is flown at a constant speed as much as possible along the overhead power transmission line for which an abnormality is to be detected, and the distance between the helicopter and the overhead power transmission line is measured using the radio distance meter 12. The measurement antenna 10 measures radio waves from overhead power transmission lines and their equipment. Turn on the data recorder 20 or release the recording pause at the part you want to measure, digitally record the received radio wave data on the magnetic tape 22 by the data recorder 20, and at the same time move to the measurement point output from the radio distance meter 12. distance data, the output of the ground speed meter 14, and position information from the fixed position marker 16 are also recorded on the magnetic tape 2 of the data recorder 20.
Digitally records on two separate data channels.

Although it is desirable that the distance between the helicopter and the overhead power transmission line be constant, as will be described later, in this embodiment, radio wave attenuation due to distance is corrected, so the distance between the helicopter and the overhead power transmission line may vary. It is possible to appropriately determine and detect abnormalities even when

The magnetic tape 22 with the measured data recorded in this way is played back on the ground, and the measured radio wave data is analyzed by a computer.
Create a graph to determine abnormal locations. FIG. 1B shows a block diagram of the structure of the analysis plotting device installed on the ground. 1st
In Figure B, 24 is a reproducing device that reproduces recorded data on the magnetic tape 22, and 90 is a computer that is in charge of analysis processing. The reproducing device 24 outputs the measured radio wave data by the measuring antenna 10 to the output signal line 24a, the power transmission line distance data by the distance measuring device 112 to the output signal 24b, and the position mark data by the position fixed marker 16 to the output signal line 24c. Ground speed data from the ground speed meter 14 is output to the output signal line 24d.

The distance data on the signal line 24b is input to the statistical processing circuit 26, where it is statistically processed. Specifically, extreme values of distance data are eliminated and fluctuations thereof are smoothed. The voltage conversion circuit 28 converts the distance data output from the statistical processing circuit 26 into a voltage signal having a voltage value corresponding to the distance value.

The distance correction circuit 30 adjusts the intensity of the measured radio wave data on the signal line 24a at a predetermined constant distance according to the output of the voltage conversion circuit 28, that is, the distance value between the antenna 10 and the overhead power transmission line to be observed and its equipment. Correct to. Even if a helicopter were to fly parallel to overhead power lines, it is practically impossible to maintain a constant distance to the overhead power lines.

The radio waves emitted from overhead power lines and their equipment are theoretically inversely proportional to the square of the distance. Therefore, the measured radio wave data is corrected to a value at a certain distance using distance data measured at the same time. In addition, instead of performing correction using such a theoretical formula, the attenuation characteristics due to distance are actually measured, and the measured radio wave data is applied to the attenuation characteristic function obtained through measurement to correct the value at a certain distance. Good too. Regardless of the correction method, the distance correction circuit 30 is actually constituted by a digital arithmetic circuit, so it is easy to implement.

The measured radio wave data whose distance has been corrected by the distance correction circuit 30 is supplied to a fast Fourier transform circuit (FFT) 34 and a sudden wave detection circuit 36 via a buffer memory 32 . In this embodiment, due to processing capacity, the buffer memory 3
2, 4096 pieces of measured radio wave data are applied to the sudden wave detection circuit 36, and 2048 pieces of measured radio wave data are applied from the beginning of the 4096 pieces of data.
data is supplied to the fast Fourier transform circuit 34. The fast Fourier transform circuit 34 divides the measured radio wave data into 22 frequency channels and outputs the divided frequency channels. Table 1 shows the frequency bands of the output channels of the fast Fourier transform circuit 34. Of course, Table 1 is an example, and the present invention is not limited to such frequency divisions. However, according to the present invention, it takes at most 10K to detect abnormalities in overhead power transmission lines and their equipment.
All you have to do is check the frequency band up to Hz.

Since the output of the distance correction circuit 30 is distance corrected, as long as the grounding resistance of the tower of the overhead power transmission line is appropriate, the input signals of the fast Fourier transform circuit 34 and the sudden wave detection circuit 36 are approximately constant at 50 or 60 Hz. The signal waveform is a fundamental wave with an amplitude superimposed on a noise component and a sudden component due to corona discharge that occurs partially due to broken wires or poor insulation of the insulator. The sudden wave detection circuit 36 is a circuit that detects such sudden waves superimposed on the fundamental wave.

The internal configuration of the sudden wave detection circuit 36 will be explained in detail later. The sudden wave detection circuit 36 detects the timing (i.e., generation position), peak value, duration, and processing period (4
A signal indicating the number of occurrences within the 096 data) is output.

The position mark data on the signal line 24c output from the reproduction device 24 is applied to the mark extraction circuit 38. The mark extraction circuit 38 selects, among the input position mark data,
For example, the position mark data of an object whose ground position is known, such as a steel tower, is extracted and a corresponding pulse signal is generated.

Further, the speed data on the signal line 24d output from the reproducing device 24 is input to the statistical processing circuit 42, where it is statistically processed. The output of the statistical processing circuit 42 is sent to the voltage conversion circuit 4.
4 into a voltage signal.

Table 1: Overhead transmission lines and their equipment are subject to defects that exist over long distances due to corrosion and deterioration of overhead transmission lines, as well as specific defects such as poor earthing resistance of towers, broken wires, and poor insulation of insulators. There is a malfunction or abnormality that occurs in the part. The former appears as a low-frequency noise component that is superimposed on the 50 or 60 Hz fundamental wave over a certain length along the overhead power transmission line in the measured radio wave data (for example, the output of the distance correction circuit 30); appears as a sudden wave superimposed at a position corresponding to a fault or abnormality, or as a fluctuation component over a short period.

As a result of observation, such noise components suggest that the overhead power transmission line is aging or that it is time to replace it.
It was found to have a frequency band of ~6 KHz. Therefore, in this embodiment, the overhead power transmission line and its equipment are
An abnormality degree determination circuit 46 is provided which indicates the abnormality detection time, replacement time, etc. as an index.

The internal configuration of the abnormality degree determination circuit 46 is illustrated in FIG.

In FIG. 2, a division circuit 52 divides the wave height of the sudden wave by the amplitude of the fundamental wave, and an indexing circuit 54 divides the output value of the division circuit 52 into four levels, for example, 1, 2, and 3.4. It fits and outputs an index value indicating the applicable category. Based on this index value, it is possible to decide whether to conduct an urgent on-site investigation or continuous monitoring.
You can objectively judge whether monitoring is unnecessary for the time being.

Each frequency component of the measured radio wave data (output of the fast Fourier transform circuit 34), the height and width of the sudden wave, the number of sudden waves per unit processing section, the wave height value of the fundamental wave at the sudden wave generation position, etc. (the sudden wave output of the detection circuit 36), output of the abnormality degree determination circuit 46, distance value to the power transmission line (voltage conversion circuit 28),
output) and fixed position marks are input into a plotting device 48, such as a plotter or printer, and each measured and analyzed data value is printed on paper as the measurement time elapses (i.e., along the measured overhead power line). graphed. Flight speed data (output of voltage conversion circuit 44) is added to each of the above data.
In addition, it is preferable that the data be recorded on a large-capacity recording medium, such as a magneto-optical disk, by the data recording device 49 for subsequent re-analysis and more detailed analysis.

FIG. 3 shows an example of the output of the drawing device 48. However, the output of the sudden wave detection circuit 36 (number of sudden waves, width, height, and cut level for sudden wave detection), the distance to the power transmission line,
Also, only the outputs of CHI to CH15 of the fast Fourier transform circuit 34 are shown. Fixed line means mark extraction circuit 38
The output is a position reference line based on a fixed position mark signal.

FIG. 4 shows a block diagram of the circuit configuration of the sudden wave detection circuit 36, and FIG. 5 is a waveform diagram in the process of separating the sudden waves and calculating the generation position of the sudden waves.

For ease of understanding, FIG. 5 is illustrated in the form of an analog signal. As described above, the sudden wave detection circuit 36 is supplied with 4096 pieces of data from the buffer memory 32. The input signal waveform of the sudden wave detection circuit 36 is 50 or 60H, as illustrated in FIG. 5(a).
The waveform is a fundamental wave of z, superimposed with noise and sudden waves caused by corona discharge caused by broken wires, etc. Data from buffer memory 32 is transferred to a digital low-pass
A filter (LPF) 60 and a digital bypass filter (HPF) 62 separate the signal into a fundamental wave component and a frequency component higher than the fundamental wave but not including the fundamental wave. That is, the LPF 60 is a digital filter for extracting fundamental wave components of 50 to 60 Hz, and the HPF 62 is a digital filter for extracting components other than the fundamental wave, specifically, components of 80 Hz or higher.

The output of the HPF 62 has a waveform consisting of noise and sudden waves, as shown in FIG. 5(b), for example.

FIG. 5(C) is an enlarged view of FIG. 5(b). The peak detection circuit 64 detects positive and negative peak values from the output of the HPF 62, and the absolute value circuit 66 converts the peak values detected by the peak detection circuit 64 into positive values. The peak detection may be performed after first converting the output of the HPF 62 into an absolute value. The peak detected by the peak detection circuit 64 includes both a sudden wave and noise. The statistical processing circuit 68 is an absolute value circuit 66
A noise level is calculated by performing statistical calculations on the positive peak values outputted from the device to reduce data variations and, if necessary, removing high frequency components higher than a predetermined value. The calculated noise level is applied to the noise cut circuit 70.

The output of the HPF 62 is also converted from a negative value into a positive value by an absolute value circuit 72 and is applied to a noise cut circuit 70 . Noise cut circuit 70 subtracts the noise level from statistical processing circuit 68 from the output data of absolute value circuit 72. Through this subtraction process, the noise cut circuit 70
The output of will contain only the sudden wave. Figure 5(d)
shows the output signal waveform of the noise cut circuit 70. The output of the noise cut circuit 70 is applied to a sudden wave measurement circuit 76. The sudden wave calculation circuit 76 calculates the sudden wave generation position, height, and processing section (
The number of sudden waves per 4096 pieces of data) and the period of occurrence (ie, width) of closely spaced sudden waves are calculated.

The fundamental wave height calculation circuit 78 is a circuit that calculates the wave height value of the fundamental wave at the sudden wave generation position. Specifically, for example, the sudden wave generation timing signal from the sudden wave calculation circuit 76 is used as a sampling clock, and the LPF 60 The output of is being sampled. The fundamental wave height value calculated by the fundamental wave height calculation circuit 78 is applied to the output circuit 80. The output circuit 80 is also applied with data regarding the sudden wave calculated by the sudden wave calculating circuit 76, and the output circuit 80 sends these data to the drawing device via individual signal lines or bus-type signal lines. 48 and a data recording device 49.

The output circuit 80 functions as an output buffer and as a circuit that adjusts the output timing of each data to be output.

According to the present invention, it has been found that each frequency component of a measured radio wave exhibits the following changes in response to a malfunction in an overhead power transmission line and its equipment. That is, if the wires of an overhead power transmission line are corroded or dirty, the noise level increases depending on the degree of corrosion or dirt. When a wire breaks, a sharp sudden wave is generated depending on the degree of breakage, and the width of the sudden wave changes depending on the size of the break. Furthermore, if the ground resistance of the steel tower is poor, the level of the fundamental wave changes, and level changes also occur in other frequency bands. for example,
In Figure 3, A and B (both CHI) indicate poor grounding resistance of the steel tower, C (CH4) and D (CH12) indicate corrosion or contamination of the wire, and the sudden wave in the sudden wave detection results is , implying that there is a sleeve or spacer at that position, or that there is a broken wire.

The present invention is not limited to the configuration of the above embodiment.

For example, it is easy to realize some or all of the circuit blocks illustrated in the drawings individually or by one digital arithmetic processing device, and it goes without saying that this also falls within the technical scope of the present invention.

[Effects of the Invention] As can be easily understood from the above description, according to the present invention, it is possible to precisely detect defects in overhead power transmission lines and their equipment, as well as their contents and locations. In addition, since the measured value is distance-corrected based on the measured distance to the measurement target, there is no need to keep the measurement equipment at a strictly fixed distance from the overhead power transmission line and its equipment to be measured, making it possible to safely use the helicopter.
It is possible to safely operate flying objects such as Furthermore, not only is measurement easier, but the content and extent of the malfunction can be determined more accurately, eliminating individual differences and day-to-day differences in determination.

[Brief explanation of drawings]

Figure 1A is a block diagram of the configuration of on-board equipment mounted on the helicopter, Figure 1B is a block diagram of the analysis plotting device installed on the ground, and Figure 2 is the abnormality degree determination circuit 46 of Figure 1B.
3 is an example of the sudden wave detection result and each frequency component of the received radio wave, FIG. 4 is a circuit configuration block diagram of the sudden wave detection circuit 36, and FIG. 5 is the inside of the sudden wave detection circuit 36. FIG. 3 is an analog signal waveform diagram at each processing stage. 10: Measuring antenna 12: Radio distance meter 14 Two ground speed meters 16: Fixed position marker 18: Calendar clock 2
0=Data recorder 22: Magnetic tape 24: Playback device 26: Statistical processing circuit 28: Voltage conversion circuit 30:
Distance correction circuit 32: Buffer memory 34: Fast Fourier transform circuit (FFT) 36: Sudden wave detection circuit
38: Mark extraction circuit 42: Statistical processing circuit 44: Voltage conversion circuit 46: Abnormality determination circuit 48: Plotting device
49: Data recording device t 50: Adder 52: Division circuit 54: Indexing circuit 60: LPF62: HP
F 64: Beak detection circuit 66: Absolute value circuit 68
: Statistical processing circuit 70: Noise cut circuit 72: Absolute value circuit 74: Delay circuit 76: Sudden wave calculation circuit 78
Two fundamental wave height calculation circuit 80: Output circuit 90: Computer 92°94.96: Amplifier 98: Low-pass filter 100: Pulse generation circuit

Claims (4)

[Claims] (1) A method of detecting abnormalities in overhead power transmission lines and their equipment, in which radio waves emitted from the overhead power transmission lines and their equipment are received by a measuring antenna while moving along the overhead power transmission line to be investigated. a measuring step of measuring the distance to the overhead power transmission line and its equipment using a distance measuring device and inputting a mark signal indicating an object whose location is known; and a measuring step of inputting a mark signal indicating an object whose location is known; A method for detecting abnormalities in overhead power transmission lines and their equipment, characterized by comprising an analysis step of analyzing in a low frequency band. (2) Before the analysis step, it includes a distance correction step of correcting the radio wave signal measured in the measurement step by the distance measured in the measurement step. ) method for detecting abnormalities in overhead power transmission lines and their equipment. (3) A device that uses low-frequency radio waves from overhead power transmission lines and their equipment to search for abnormal locations, including a flying object and a device that is mounted on the flying object and receives radio waves from the overhead power transmission lines and their equipment. A measuring antenna, a distance measuring means mounted on the flying object to measure the distance to the overhead power transmission line and its equipment to be searched, and a position information input means mounted on the flying object for inputting measurement position information. , a recording means that is mounted on the flying object and records on a recording medium the radio wave signal received by the measurement antenna, the distance signal from the distance measurement means, and the position information from the position information input means; and the signal recorded on the recording medium. a reproduction means for reproducing the radio wave signal; a distance correction means for correcting the distance of the radio wave signal reproduced by the reproduction means using the reproduced distance signal; and a distance correction means for correcting the distance of the radio wave signal reproduced by the reproduction means; A frequency dividing means for dividing into frequency bands, and an output means for graphically outputting at least a part of the positional information inputted by the positional information inputting means and the signal of the frequency band divided by the frequency dividing means. A device for detecting abnormalities in overhead power transmission lines and their equipment. (4) The overhead power transmission line according to claim (3), further comprising sudden wave detection means for detecting sudden waves from the radio wave signal whose distance has been corrected by the distance correction means. and equipment for detecting abnormalities in the equipment.