KR20010039078A - Aluminium Conductor Steel Reinforced Inner Corrosion Detection Method and Dector Contolled by Radio Frequency - Google Patents

Abstract

PURPOSE: A method and an apparatus for detecting inner corrosion of an ACSR wire by radio is provided to analyze or estimate the state of the installed line, thereby securing stability and reliability of power supply and economical operation of the line. CONSTITUTION: An apparatus for detecting inner corrosion of an ACSR(Aluminum Conductors Steel Reinforced) wire includes a corrosion judging part(200) having a detachable sensor head structure measuring the detect of the ACSR wire by using non-destructive method, a power supply part(100) formed with a high frequency power source supplying alternating magnetic flux and a constant current source, a signal processing unit(300) detecting output of the corrosion judging part to detect impedance characteristic due to the detect of the wire, a processor part(400) connected with the corrosion judging part and the signal processing part for receiving the detect signal with three A/D converters and storing the detect signal, controlling the motion of a motor, transmitting the measured data to a ground station system successively or intermittently, a motor driving part(500) moving an aerial station system with a DC servo motor driven by a rechargeable battery power source, a radio transmitting and receiving device(600) transmitting measured data to the ground station system or transmitting and receiving a signal controlling the motion of the motor with a PC of the ground station system, and an outputting part(700) outputting the data transmitted through the radio transmitting and receiving device according to the selection of a user.

Description

Method and device for detecting corrosion of internal wire of ASC wire by wireless {Aluminium Conductor Steel Reinforced Inner Corrosion Detection Method and Dector Contolled by Radio Frequency}

The present invention relates to a method and apparatus for detecting corrosion of wires by wireless ACSR (Aluminum Conductors Steel Reinforced). More specifically, a method and apparatus for detecting internal corrosion of ACSR wires that can analyze or predict the state of a line by detecting local corrosion defects caused by corrosion or deterioration of ACSR wires used as overhead lines in transmission and distribution lines. It is about.

The deterioration of ACSR cables used in transmission and distribution lines is caused by the interaction of a variety of factors such as the material and manufacturing method of the cables as well as the construction conditions and the exposure environment of the lines. In particular, ACSR cables have a twisted structure of galvanized stranded wire for tensioning and light aluminum stranded wire for supplying current, compared to copper stranded wire and aluminum stranded wire of the same material. . In general, processed wires are not only atmospheric corrosion but also galvanized corrosion due to the contact of dissimilar metals, crevice corrosion or fatigue corrosion caused by the wet of the wire ( Various corrosion phenomena such as fati gue corrosion occur.

Defects due to wire degradation can be detected by nondestructive tests such as the eddy current test, leakage flux test, or the use of an infrared camera. At this time, a method of quantifying the corrosion state may be a method of detecting a change in the cross-sectional area of the aluminum wire, measuring the amount of zinc deposited on the galvanized steel wire or detecting a local defect.

Meanwhile, in the UK, J. Sutton & KG Lewis, UK Corrosion, The detecti on of internal corrosion in steel reinforced aluminum overhead power line conduits, the loss of zinc layer is the most influential factor in wire life. In Japan, Fujikura (J. Iinuma & J. Endo, Fujikura Tech, Corrosion detector robot for overhead transmission lines) was developed by Northeast Electric Power Co., Ltd. Although the detector and the Fujikura electric wire have jointly developed an aluminum surface test, the detector is heavy and has problems in practical use in terms of precision. In addition, the Ontario Hydro Research Institute in Canada (DG Havard, Ontario Hydro, Aged ACSR Conductor: Part I & II) analyzes the mechanical properties and environmental factors of the cables used, develops laboratory and field methods, and forms a cable replacement committee. It is operating a reasonable wire replacement program.

In other words, although the electric wire is replaced by the old age after the installation, the deterioration state progresses variously due to environmental factors in the area where the electric wire is installed, the characteristics of the electric wire material, and the amount of power supply. Therefore, the replacement time set for a certain period as of now is not realistic. In fact, accidents such as disconnection are often caused by the influence of corrosion environment or the weakness of the wire material rather than the history of the wire as the age. Among these factors, local corrosion can cause serious problems in power supply. Therefore, the rational operation of the cable line requires a method for detecting physical conditions such as secular variation and environmental factors as well as local corrosion of the line. In fact, in order to diagnose the life of a wire, it is necessary to be able to quantitatively handle these complex factors.

As mentioned above, in the operation of the cable line which can cause serious problems in the power supply such as the disconnection of the wire due to the local defect of the wire, the current method of collective replacement in Korea after a certain period of time is used. There is a risk of economic loss caused by the power supply due to late economic replacement.

The present invention is to solve the above problems, air and air consisting of a split-through coil sensor and a processor, a motor drive system and a stable constant current source that is easy to remove and detach the structure so as to conveniently measure the degree of corrosion of the hypothesized wire It is composed of a ground plane which receives the measured data from the plane and operates the air plane by radio. The ACSR internal corrosion detector operated by radio measures the cross-sectional change of aluminum wire and loss of zinc of galvanized steel wire of ACSR wire and analyzes or predicts the condition of hypothesized line by detecting local corrosion defect due to wire corrosion or deterioration. The purpose is to provide safety, reliability and economical operation of power supplies.

1 is a structure of the processing branch line ACSR 97 [mm ² ] for explaining the present invention

Figure 2 is a solenoid coil sensor inserted ACSR for the description in the present invention

Figure 3 is a split through coil structure for description in the present invention

Figure 4 is a block diagram of a method and apparatus for detecting corrosion of ACSR wires by wireless for the purpose of explanation in the present invention

<Description of the code | symbol about the principal part of drawing>

100: power supply unit 110: high frequency power supply unit

120: constant current source 200: corrosion determination unit

300: signal processing unit 400: processor unit

410: air main controller 420: ground control

500: motor drive unit 600: wireless transmission and reception device

700: output unit

The present invention can analyze or predict the state of wires by detecting the degree of local corrosion of ACSR wires used as overhead lines for transmission and distribution lines, and the ACSR wires are made of galvanized steel strands and aluminum strands. Consists of.

Figure 1 shows ACSR 97 [mm2] used as overhead ground wire. The outer layer is composed of 12 hard aluminum wires of 3.2 [mm] in diameter and used as conductors to flow brain current or accident current to the ground.The inner layer is composed of hot dip galvanized steel wire of 3.2 [mm] in diameter. It is in charge of mechanical tension. The steel wire is galvanized to increase corrosion resistance, and an iron-zinc alloy layer is formed on the plating layer. At this time, the thickness of the zinc plating and the alloy layer is about 30 to 40 [μm].

Another type of ACSR has a structure in which light aluminum wires are twisted around a stranded steel wire galvanized in the center as shown in FIG. Thus, the outer layer of stranded aluminum is exposed to the atmosphere and is in direct contact with corrosion sources such as pollutants. In the early stage of the construction, the wetting period, which is the basic element of corrosion, is short, so that the corrosion is blocked to some extent. On the other hand, the inner layer is surrounded by the outer aluminum stranded wire layer, and moisture is hard to penetrate. However, once moisture penetrates, the wetting period is long, accelerating the corrosion rate. Corrosion also occurs due to contact between the inner and outer metals. Carbide, such as dust, has moisture and conducts electricity, which may increase the corrosion rate. That is, ACSR having such a unique structure has two major corrosion phenomena. One of them is atmospheric corrosion caused by environmental factors, the other one is electrolytic corrosion caused by the contact of these three metals, and the phenomenon is as follows.

(Ⅰ) atmospheric corrosion

The atmospheric environment affects the corrosion of metals, mainly due to humidity and oxygen, sulfur dioxide, salt and nitrogen. Moisture in the atmosphere and oxygen in the air cause chemical reactions between metals to produce sulfuric acid compounds, salt compounds and nitrogen compounds. Therefore, the corrosion of the metal is promoted and, in some cases, causes a decrease in tension, a formula or a crack.

In general, industrial and urban areas are polluted by the release of large amounts of sulfur dioxide, thus corroding metals. SO ₂ combines with moisture to form sulfuric acid compounds to promote corrosion, and in particular, may cause the formation of ACSR aluminum wire or grain boundary corrosion. Salinity, on the other hand, has a high affinity with rivers, which makes it a major cause of corrosion on wires built on shore. Typically, coastal river corrosion is reported to be about 2,000 times greater than in clean areas.

Corrosion products caused by salt or sulfur dioxide are attached between the strands of the ACSR together with the dust in the air, so they act as conductive materials and increase the corrosion rate. Corrosion of ACSR is almost neglected in clean areas, but in coastal areas there is a large impact of salinity and in industrial areas of sulfurous acid and nitrogen gas. In industrial areas, aluminum wire is mainly a problem and steel wire corrosion is a problem in coastal areas, but it is difficult to distinguish and analyze the corrosion structure of ACSR. Atmospheric concentrations of industrial areas include sulfur dioxide, nitrogen oxides and dust. Therefore, ACSR corrosion in these areas is predominantly atmospheric.

(Ii) electrolytic corrosion

As shown in FIG. 1, when the galvanized steel wire and the aluminum wire are in contact, three kinds of metals, that is, iron, zinc, and aluminum are in contact with each other. Corrosion products, dust, etc., caused by salt or sulfurous acid gas, accumulate in these parts. If moisture penetrates between these deposits, it acts as an electrolyte solution, forming a local battery. Accordingly, ionization occurs between different metals (heterometals: 異種 金 屬), and electrolytic corrosion proceeds in the order of Zn, Al, and Fe, which have a large tendency to ionize. Zinc is primarily corroded by the potential corrosion caused by the metal potential difference between the parts where aluminum and zinc are in contact, and when aluminum and steel core are in contact, aluminum is lost and the steel is exposed to the atmosphere, resulting in an exponential corrosion phenomenon. do. As a result, the conductivity decreases and the tensile strength decreases due to any form of corrosion, which increases the possibility of accidents caused by disconnection.

If the ACSR is installed near the coast for a long time, water containing salinity accumulates in the interval between the aluminum wires, and preferentially causes contact corrosion between the zinc layer of the galvanized steel wire and the internal aluminum wire, consuming zinc and exposing iron parts. In this state, this time, electrolytic corrosion occurs between the dissimilar metals of the steel wire and the aluminum wire, causing the aluminum wire to corrode. As corrosion progresses, the cross-sectional area of the aluminum part decreases, which increases the power loss of the line.

As described above, the method of detecting the defects and the degree of corrosion of electric wires, which are the major obstacles to the safety of power supply and the economical operation of electric wires, will be examined.

In general, the vortex flaw detection is a method of generating a magnetic field by a coil and placing a subject under the magnetic field to detect physical characteristics of the measurement object by a change in impedance of the coil. If a coil sensor with a constant current flows near the object to be measured, eddy currents will be generated in the object to be measured, causing a change in magnetic flux. This magnetic flux change causes a change in the impedance (resistance and inductance) inherent in the coil due to the magnetic properties of the object under test. This amount of change changes the input voltage or current of the sensor, and the characteristic of the object under test can be detected from the result.

For the solenoid coil as shown in FIG. 2, the length of the solenoid bobbin is l [m], the average radius of the bobbin is r _o [m], and the number of coils per unit length is n [times]. Let b be the radius of the sample. Further, the relative permeability of the samples is μ _r, the conductivity is _σ [S / m]. First, consider an air-cored coil without a sample. When an alternating current of effective value I flows through the coil as an input, an equal magnetic field H = nI is formed at the core. At this time, the internal magnetic core density is B _o = μ _o H. Where μ _o is the permeability of air in μ _o = 4π × 10 ⁻⁷ [H / m].

Since the magnetic flux is not attenuated in the air, in the case of an air core coil, no eddy current occurs and the impedance of the sensor is described as follows.

Zo = Ro + jωLo

In this case, the resistance Ro is an intrinsic component of the coil composed of copper wire, and a relatively small value, and the inductance is a component in which the magnetic flux generated by the inflow alternating current interlinks with the coil.

On the other hand, when a conductor is inserted into the coil, an eddy current is generated on the surface of the conductor, and the magnetic flux caused by this current is generated in a direction that disturbs the main magnetic flux. The conductor acts like the secondary side of the transformer when the solenoid sensor is assumed as primary, so the impedance of the sensor is changed as follows for the same power supply frequency. In other words,

Z = R + jωL

At this time, among the impedances, the resistance always increases and the inductance varies depending on the material of the sample. In other words, the coil impedance is determined by the speed and attenuation coefficient of the electromagnetic wave of the object under test, and the amount of change makes it possible to change the input voltage or current of the sensor and detect the characteristic of the object under test from the result.

In general, wire defects are mainly caused by corrosion of the galvanized layer of steel wire and change of cross section of aluminum wire. In addition, the pure zinc thickness of the galvanizing thickness is only about 20 [㎛] and about 20 to 30 [㎛] is given as an alloy layer of zinc and iron. Since zinc has high conductivity and nonmagnetic material, it is difficult for external magnetic flux to penetrate inside by high frequency magnetic flux. Therefore, vortex generation of steel wire with internal relative permeability of 20-50 is not large. However, when the galvanized steel is corroded, the internal iron is exposed and the vortex generation is significantly increased. Therefore, as the main magnetic flux is reduced, the impedance is increased and the output is increased.

Changes in cross-sectional area of aluminum wires, which are typically nonmagnetic, appear mainly as changes in inductance at high frequencies. Therefore, the change in the cross-sectional area of the aluminum wire changes only the imaginary part of the output voltage. However, in galvanized steel wires, the resistance and inductance change simultaneously, so the output voltage changes simultaneously with the real part and the imaginary part. Therefore, it can be determined that the change in the phase of the detection signal with respect to the reference signal mainly indicates the reaction of the zinc plated layer. As a result, when the magnitude and phase of the output are detected by the eddy current sensor, defects in the galvanized layer and the aluminum wire can be estimated.

On the other hand, in order to be a practical sensor that is convenient to use in the construction of the wire, as shown in Figure 2 to take a solenoid coil sensor or other shape while wrapping the wire in a solid line, that is, manufactured in a structure that is easy to attach and detach the sensor head Should be. Therefore, as shown in FIG. 3, the use of a separate encircling coil consisting of two connectors having a relatively simple structure in the form of a clip, wherein the connector is a coil in the circumferential portion of the cylindrical plastic supporting the circular excitation coil You can pull it out vertically and configure the connection to the outside.

Thus, the present invention will be described in detail with reference to the accompanying drawings by using the corrosion detection principle of the ACSR wire used in the transmission line and distribution line as follows.

Figure 4 is a block diagram of a method and apparatus for detecting ACSR wire internal corrosion by wireless according to the present invention.

The configuration is described as an example applied to ACSR wires mainly used for processing ground wires of transmission lines. Corrosion determination unit 200 having a detachable sensor head structure that largely measures whether a wire is defective using a non-destructive method and And a power supply unit 100 including a radio frequency power source 1 10 and a constant current source 120 for supplying alternating magnetic flux to the sensor coil in the corrosion plate 200, and an electric wire. In order to detect the impedance characteristic due to the defect of the signal processing unit (SPU) 300 for detecting the output of the corrosion determination unit 200, the corrosion determination unit 200 and the signal processing device 300 is connected A processor 400 having a function of receiving a detection signal from three A / D converters and storing them in a memory or transmitting measured data to a ground plane continuously or intermittently and controlling a motor operation; The motor drive unit 500 which moves the corrosion detection device (hereinafter referred to as the air plane) to a DC servo motor driven by a circle, and transmits the measurement data to the ground or a signal for controlling the motor operation of the air plane with the PC of the ground plane. A wireless transmitting and receiving device 600 in charge of the function of transmitting and receiving, and the output unit 700 for outputting data transmitted through the wireless transmitting and receiving device 600 according to the user's selection.

Specifically, the power supply unit 100 has to supply alternating magnetic flux through a coil in order to detect whether the wire is defective by using the eddy current detection method. In order to supply a constant current to the high frequency power supply unit 110 and the sensor, a constant current source 120 circuit is configured to change the current supplied to the sensor to 7.7 to 10 [kW] using a power amplifier having a relatively high frequency characteristic. have.

The corrosion plate 200 uses a split-through coil sensor (refer to FIG. 3) having a detachable head structure for convenient use in a solid line, and when the length of the bobbin is increased, the average corrosion can be detected. Although it is difficult to accurately detect local defects, the coil width is 25 [mm] and the inner diameter is 26 [mm] for ACSR cable 95 [mm2] and 97 [mm2]. It is possible to detect local defects in the electric wires.

The signal processor 300 is configured to change three high frequency sinusoidal signals, which are output signals of a sensor, to an effective value, increase an output signal with an amplifier, and apply the same to a 16 [bit] A / D converter of a main processor.

The processor unit 400 is largely composed of an air main controller 410 and the ground controller 420. The main air processor 410 is a command for receiving operation of the sensor unit output, the function of receiving the output signal of the sensor to the AD converter and storing in the memory, the function of wirelessly transmitting the measurement data to the terrestrial receiver, the flaw detector driving motor It is designed to have on / off, forward / reverse and speed control functions, speed (distance) measurement of the motor for the measurement section of the flaw detector, and other functions such as control and diagnostic functions of the air vehicle and the ground controller.

The ground controller 420 is designed to be capable of mutual communication with the air processor and to have functions such as receiving measurement data, transmitting it to a PC, and wireless control of the air plane operation. It is configured to adjust speed, position, direction and so on. The processor is configured to control the speed in a PWM manner with the motor control element LM629 and to read the position with the encoder signal of the motor.

In the motor driving unit 500, a motor driven by a rechargeable battery power to move the air plane is used as a DC servo motor (servo motor) because it uses a weight or a simple structure of a driver and a controller. Is used to detect the distance and convert the distance.

The flaw detector is basically required to send and receive digital data stored in the processor's memory and to control the motor operation of the flaw detector with the PC of the ground plane. Two sets of transmitters and receivers should be used in each case, but if a duplex communication or a half duplex wireless system is used, bilateral communication is possible. Therefore, the duplex type wireless modem is used in the wireless transmitter / receiver 600. It consists of one transmitter and one receiver.

The PC of the output unit 700 has a basic wire history data (wire type, line name, voltage, date of construction, etc.) in a database in advance, and a sensor according to a flaw detection distance using data measured using a wire corrosion detection device. Analytical results such as output signal and quantified wire corrosion and grade characteristics can be displayed on the LCD screen of the PC.

<Application example>

Tests were conducted to verify the field applicability of the ACSR wire corrosion detector prototype. The test was conducted in Gochang 765 kV demonstration test site (99.8.12-8.13) to verify the operation and function of the flaw detector, and the state of the measurement program, such as the cable running test of the flaw detector, the communication status of the radio control operation, and the transmission / reception status of the wireless data. The overhead line ACSR-AW 120 mm2 between # 1 and # 2 towers was tested. As a result of conducting 1m, 10m, 50m in the cable running test, it was found that the motor operation and the data reception operation were all normal. Especially, it was found that the motor moved correctly to the initial position even in the case of reverse rotation. It could be seen that. The results of empirical tests were conducted on Seosan # 2 T / L in case of cease-fire in the KEPCO, to verify that there were no errors or disturbances in data transmission due to the electromagnetic field caused by liveliness (99.10). .14-10.15) There was no problem in detecting defect characteristics and transmitting data of overhead wires. As can be seen from the above, the possibility of field application of the developed flaw detector which accurately detects the degree of defect and corrosion of electric wire was confirmed.

In order to solve the degradation and local corrosion of ACSR wires, the present invention uses the ACSR wire internal corrosion detection method and apparatus which are controlled from the ground by wireless operation to measure the cross-sectional area change of aluminum wires and zinc loss of galvanized steel wires of ACSR wires. By detecting local corrosion defects caused by corrosion or deterioration of wires, it is possible to secure safety and reliability of power supply and economical operation of power lines by analyzing or predicting the condition of hypothesized lines.

Claims (5)

A device for wirelessly detecting internal corrosion of ACSR wires, which are used as overhead lines for transmission lines, by means of a non-destructive method of detecting and detecting a wire defect from the ACSR wires. Corrosion plate 200, the high-frequency power supply unit 110 to supply alternating flux to the sensor coil in the corrosion plate and the power supply unit 100 composed of a constant current circuit, and the corrosion plate to detect the impedance characteristics due to wire defects It is connected to the signal processing unit 300 to detect the output of the government, the corrosion judgment unit 20 0 and the signal processing device to receive and store the detection signal to the three A / D converter or to control the operation of the motor and to measure the measured data The processor unit 400 has a function of continuously or intermittently transmitting to the ground, and a DC servo motor driven by a rechargeable battery power source to move the air plane. The wireless drive / receiver 600 and the wireless drive / receiver 600 are responsible for transmitting and receiving the measurement data to the motor drive unit 500 and the ground plane or to control the motor operation of the air plane to the ground plane PC. ACSR wire internal corrosion detection device by wireless, characterized in that the output unit 700 for outputting the data transmitted through the receiver 600 according to the user's selection. According to claim 1, Corrosion plate 200 has a removable head structure to be convenient to use in a solid line, characterized in that the split through type coil having a variety of inner diameter in consideration of the thickness and the filling rate of the wire. Corrosion detection device of ACSR cable by wireless. The air processor main processor 410 of claim 1, wherein the processor unit 400 may continuously and intermittently transmit the speed and position control function of the air drive motor and the corrosion measurement data to the ground by wireless control. An ACSR electric wire corrosion detection apparatus according to claim 1, characterized by comprising a processor of the controller 420 and a processor for the interface of the DC servo motor. The method of claim 1, wherein the output means uses the PC data on the ground that is programmed in the database DB of the defect measurement data of the wire transmitted through the transmission and reception device in advance to the flaw detection distance through the LCD screen of the PC. ACSR wire internal corrosion detection device according to the wireless sensor, characterized in that configured to display the sensor output signal and the quantified corrosion degree and grade characteristics graph. In the flaw detector which detects the defect degree inside the ACSR cable while traveling along the overhead line of the transmission line by radio operation, in order to supply the alternating magnetic flux through the coil in detecting the defect of the wire by using the eddy current method. Generating a high frequency sinusoidal signal of 100 [kW] in the power supply unit 110 and a constant current source circuit that can be varied from 7.7 to 10 [kW] using a power amplifier having good high frequency characteristics to supply a constant current to the sensor. And detecting the internal corrosion state of the wire by estimating the defect of the galvanized layer and the aluminum wire of the ACSR wire by detecting the magnitude and phase of the coil sensor induced by the constant current source applied to each wire inside the ACSR wire. ACSR wire internal corrosion detection method by a wireless, characterized in that consisting of a step.