KR20030070883A - Line Identity Detector for Underground Power Cable - Google Patents

Abstract

PURPOSE: An apparatus for detecting an underground distribution power cable is provided to perform effectively a detecting process by fabricating the detection apparatus as a clamp type small-sized measuring unit. CONSTITUTION: An apparatus for detecting an underground distribution power cable includes a couple of power line couplers(102,103), a power cable communication modem portion, a communication mode switch(104), a CPU(114), an LCD panel(110), and a power supply portion. The power line couplers(102,103) are used for extracting or inputting communication signals from or to a power line. The power cable communication modem portion connects the power line couplers(102,103) to the CPU(114). The communication mode switch(104) is used for selecting one of a receiving mode and a transmitting mode. The CPU(114) is used for controlling a transmitting process and a receiving process. The LCD panel(110) is used for displaying a level of the received signal as the number. The power supply portion supplies necessary power to each element.

Description

Line Identity Detector for Underground Power Cable

In the present invention, when searching for complex trunk cables in a duct at both ends of a cable installed in a underground distribution line by a direct buried method or a pipeline buried method, or in a general electric or private electric facility, the same cable line is visible to the naked eye. The present invention relates to a device for determining whether the same cable line is carried out by performing a simple measurement in a live state when the identification tag cannot be determined or when the identification tag is attached to both ends of the cable but the authenticity of the identification tag is to be checked.

More specifically, a certain signal is transmitted to a power line communication transmitter using a non-contact power line coupler from a sheath line removing portion of an underground submerged distribution line, and a sheath line removing portion is also applied to the other end. Receive level is measured by a power line communication receiver using a non-contact power line coupler.Measures all unknown cables among the cables of the same specification and selects the cable with the highest reception level and the cable currently being transmitted from the other end. The same cable is used for discrimination.

Now, in considering the prior art in the technical field to which the present invention belongs, let's take a look at the contents disclosed in the underground cable system detector and the patent publication currently purchased and used by the Korea Electric Power Corporation.

Considering the underground cable system detector currently purchased and used by KEPCO with the KEPCO purchase specification as the center, the current sensor is installed at both ends of underground cable in the live state to detect the magnitude and phase of the current, It is to determine whether the same cable is used by transmitting and receiving information at both ends through a wired transmission line installed in the network, and inputting the same to a notebook PC having a program for converting and analyzing the information.

However, this underground cable system detector is too complicated and requires mobilization to the PC. Especially, it is too cumbersome to detect and install the wired communication line at both ends before the measurement and after the measurement.

Patent No. 1990-0003637 (published date: March 26, 1990, registration number: Patent 199-0005700 , publication date: August 02, 1991) is the name of the invention for high voltage underground distribution lines As an upper discriminator, it is a device that makes it possible to compare and detect the presence of an AC input signal and the phase difference between two input signals simultaneously by using the generated induced voltage of the inspection confirmation terminal of the special high voltage underground distribution line switchgear.

Since the top separator for underground distribution lines can be detected only at the inspection confirmation terminal of the switchgear, it cannot be used in various cases requiring verification at the manhole unit of the underground section.In addition, the complexity of the measuring equipment and the wired communication transmission line at both ends It needs to be temporarily installed before measurement and removed after measurement.

Publication No. 2002-0036390 (published date: May 16, 2002), which was searched in the patent publication, is a method for checking the life and phase of underground distribution lines, and transmits signals having a predetermined frequency and period at a power control base. By using a current transformer into the underground distribution line cable, and detecting the signal using a receiving current transformer at the work site to check the life and phase of the cable.

The life and phase inspection methods for underground distribution lines are to be provided for each line and each phase of high-voltage signal injection current transformers at power control bases or distribution substations. If a current transformer is installed at the outlet of each line, a blocking filter should be installed at the power stage of the current transformer. Otherwise, the same signal is detected on all the lines in the site due to the flow of signals to all distribution lines connected to the same bus, so that at least one line is installed except in one section. In that case, the test becomes impossible. Currently, the installation of a large current blocking filter is practically impossible due to the excessive space required, even if the cost is excluded.

As described above, it is impossible to easily perform the line detection of underground cables with the practical techniques or the proposed techniques.

The present invention was devised to solve the above-mentioned problems. When the same cable line cannot be discriminated with the naked eye at both ends of the underground distribution line, a simple measurement is performed in a live state to determine whether the same cable line is present. How to determine. That is, a signal is transmitted from the sheath line removal part of the underground submerged distribution line to the power line communication transmitter using a non-contact power line coupler, and the other end is a non-contact type from the sheath line removal part. Receive level is measured by a power line communication receiver using a power line combiner.Measures all unidentified cables among the cables of the same specification, and distinguishes the cable with the highest received level and the cable currently being transmitted from the other end as the same cable. That's how. Therefore, the signal transmission at the transmitting end and the signal reception at the receiving end are performed by power line communication. Therefore, the performance of the power line communication technology is the key to achieving the object of the present invention. However, even the power line communication technology to date can realize a communication distance of more than 2 km in an environment without special noise such as underground distribution lines. However, the technical task of the present invention is to devise a method for integrating power line communication with a power line in a non-contact manner, thereby eliminating the complexity and risk of detection by the direct contact method and enabling efficient detection.

1 is a block diagram of the underground cable line detector and a case of installing a pair of underground cable line detector according to the present invention at both ends of the power line at the same time.

FIG. 2 is a circuit diagram for explaining a theoretical principle when a pair of underground cable line detection devices according to the present invention are installed at points A and B of a power line for measurement.

Underground cable line detection device of the present invention for achieving the above objects is a non-contact coupled power line communication, the non-contact power line coupler (102,103) is easily mounted on the line to be measured using a split type core (Spilit Type Core) Or to be removed.

First of all, the method of detecting the same cable line among the numerous cables installed in the underground distribution line is to install two underground cable line detection devices using power line communication at both ends of the detection points, respectively. Using the power line communication modem, each of which has a non-contact power line coupler installed at the sheath line elimination area, the reception level of the receiver is measured by the following two-stage measurement method while transmitting and receiving communication signals through power line communication between both ends.

In the first stage of measurement, any one of the underground cable line detectors is set to the transmission mode, and the underground cable line detector of the other end is set to the reception mode, and the transmitting underground cable line detector is mounted on the cable line requiring detection. The communication signal is continuously transmitted, and the receiving underground cable line detection device measures and records the level of the received signal alternately for each of the unknown cable lines having the same specification as the transmitting cable line currently transmitting the communication signal. Select and display the cable line with the highest reception level.

In the second stage measurement, the communication mode of the receiving underground cable line detection device in the first stage measurement is set to the transmission mode, and the communication signal is continuously installed by attaching it to the cable line having the highest reception level in the first stage measurement. Receive all the unknown cable lines with the same specifications as the cable lines that were equipped with the detection device during the first stage measurement, with the communication mode of the underground cable line detector for the first stage measurement as the receiving mode. Measure and record each signal level, but select and record the cable line with the highest reception level.

In analyzing the measurement results of the first and second stages, the transmission line cable line in the first stage measurement and the cable line recording the highest reception level in the second stage measurement match, If the transmitting device is attached to the cable line with the highest reception level in the second stage of measurement, the cable line at the two measuring points is determined to be the same cable line.

The principle, configuration, and operations of the underground cable line detection device configured to implement these functions will be described in detail based on the accompanying drawings as follows.

FIG. 1 is a block diagram illustrating a case where a pair of two underground cable line detection devices according to the present invention are installed at both ends of a power line and a configuration diagram of the underground cable line detection device.

Underground cable connections can be made at every manhole if necessary, but cables on tracks that pass through the path may cross several manholes and create connection points. In any case, a connection point always occurs, and at that connection, the sheath lines 101 are always grounded. Non-contact power line couplers (Coupler) (102, 103) is installed in the cable portion from which the sheath line (101) is removed at such a grounding place to form a power line communication modem.

Non-contact power line coupler (Coupler) (102,103) has a function of transmitting a communication signal to the power line or extracting the communication signal from the power line, it is used by winding a predetermined number of windings in a ferrite core having excellent high frequency characteristics, the core The Spilit Type Core allows easy mounting and removal of live power lines.

The configuration of the power line communication modem is a filter and amplifier 108 for filtering and tuning amplifying and outputting a communication signal extracted by the non-contact power line coupler (Coupler) (102,103) and the contactless power line coupler (Coupler) (102,103). And a CPU 114 having a program connected to an output terminal of the filter and the amplifier 108 to perform a purpose and control of the system, and controlling a carrier of a communication signal under the control of the CPU 114. A carrier controller 107 to output the power, a carrier amplifier 106 for voltage-amplifying a carrier signal output from the carrier controller 107, and a carrier signal output from the carrier amplifier 106 to amplify a non-contact power line coupler ( And a power amplifier 105 for transmitting to couplers 102 and 103.

The function of the CPU 114 is not only a built-in program that performs system control of the power line communication modem, but also calculates and stores input data, converts an analog input signal into a digital signal, and calculates a reception level thereof. The data is transmitted as a communication signal, and a carrier oscillator (Carrier OSC.) Is built in to generate a carrier signal, and a serial communication interface (SCI) is built in for a direct thermal communication interface. In addition, a function of the LCD driver capable of driving the LCD display panel 110 is built.

The CPU 114 is connected to an EPROM 109 for storing necessary data and programs which are designated in advance in case of power failure.

The LCD display panel 110 has a function of numerically displaying the reception level calculated by the CPU 114.

In the place where the low voltage power can be supplied, the system is driven by the DC power supply supplied through the power splice unit 113, and since the low voltage power cannot be supplied during the measurement of the high voltage cable, the charger 112 and the storage battery are normally used. Through 111, it can be stored and used.

However, since the power line communication described herein uses the ASK (Amplitude Shift Modulation) method as one of many power line communication methods, there is no limitation on the combination of the non-contact power line coupler and the power line communication method.

FIG. 2 is a circuit diagram illustrating a theoretical principle in the case where a pair of two underground cable line detection devices according to the present invention are installed at points A and B of a power line and measured.

In the figure, only one distribution line is supplied from the power transformer of the substation, but in practice, four to five distribution lines are connected in parallel via bus lines, and a load transformer connected to one distribution line is (A), Although shown in (B) and (C), in the actual distribution line, dozens to hundred load transformers are connected in parallel.

In this environment, the cable between the measuring point A and the measuring point B is measured using two underground cable line detection apparatuses of the present invention as an example.

First, when the transmission signal is inputted at the RE point of the measuring point (A), the signal passes through the RF RG RH RI RJ, passes through the windings of two phases of the load transformer (C), and then passes from SJ to SI SH. The circuit is formed by passing the R RB RC RD through the windings of the two phases of the power transformer and reaching the RE point. This refers to a circuit configuration, but the actual circuit configuration is very large, and all the circuits are connected in parallel. There may be circuits for the windings of a number of load transformers installed in parallel between the power transformer and the measuring point (A), and circuits for the windings of many load transformers installed in parallel from the end of the line after the measuring point (A). Can be. In addition, a large number of circuits are formed through the direct grounding of the power transformer and each load transformer. However, even if there are a large number of formed circuits as described above, RF points are divided into many parallel circuits only after the common. Therefore, the SF or TF point is only one circuit among many formed circuits, so the reception level of power line communication is inevitably lower than the RF point. By comparing and analyzing the difference in the reception level, it is possible to determine the same cable.

As described above, the underground cable line detection device according to the present invention is manufactured by using a clamp-type small measuring instrument and utilized in the underground distribution line, thereby efficiently performing cable expansion, replacement work, repair work, and supply transformer search. Economic benefits can be enhanced and much simpler, safer and faster than conventional methods.

In addition, the underground cable line detection apparatus according to the present invention is a device that can greatly improve the work efficiency by utilizing when searching for a complex trunk cable in a general electrical equipment or a private electrical equipment.

Claims (4)

In the method of detecting the same cable line among the numerous cables installed in the underground distribution line, Install two underground cable line detectors using power line communication at both ends of the detection points, and use a power line communication modem to install contactless power line couplers 102 and 103 at the cable line sheath line removal sites, respectively. Measure the reception level of the receiver by the following two-stage measurement method while transmitting and receiving communication signal by power line communication between both ends, In the first stage measurement, the communication mode 104 of a group of underground cable line detection devices is set to the transmission mode, and the underground cable line detection device of the opposite end is set to the reception mode, and the transmitting underground cable line detection device needs detection. It is installed on the cable line to transmit the communication signal continuously, and the receiving underground cable line detection device has the same specification as the transmitting cable line currently transmitting the communication signal, and alternately checks the level of the received signal in both unidentified cable lines. Select the cable line with the highest reception level by measuring In the second stage measurement, the communication mode 104 of the receiving side underground cable line detection device in the first stage measurement is set to the transmission mode, and the communication signal is mounted on the cable line having the highest reception level in the first stage measurement. Are transmitted continuously, and the communication mode of the underground cable line detecting device at the first stage of measurement is set to the receiving mode, and all of the unidentified cable lines having the same specifications and the same as those of the cable line equipped with the detecting device at the first stage of measurement are replaced. Selecting a cable line having the highest reception level by measuring the level of the raw signal and determining the same cable line when the first and second measurement results match. Underground cable track detector. The underground cable line detection apparatus according to claim 1, wherein a method for discriminating the same cable line based on the first step measurement result is used. The method of claim 1, Non-contact power line coupler (102, 103) using a split type core having a high frequency characteristic of inputting a communication signal to the power line or extracting the communication signal from the power line, In the reception mode, the communication signal is received from the non-contact power line couplers 102 and 103 and the signal is input to the CPU 114 through filtration and amplification. In the transmission mode, the communication signal of the CPU 114 is amplified to amplify the non-contact power line coupler ( A power line communication modem unit having a function of transmitting to 102, 103); A communication mode switch 104 capable of selecting a reception mode and a transmission mode of power line communication; Converts the analog input signal into a digital signal, calculates and stores the received communication signal, transmits the retained data as the communication signal, and has a built-in control program for controlling the transmission and reception communication, and the LCD driving the LCD panel 110. A CPU 114 having a built-in driver, an LCD display panel 110 which displays the level of the received signal numerically, and a power supply unit capable of supplying and discharging the required power to the entire device. Cable line detector. 4. The underground cable line detection apparatus according to claim 3, wherein the non-contact power line coupler (102, 103) is configured in a hanger type so that the contactless power line coupler (102,103) can be easily attached and detached to the line under test during field work.