KR101680063B1 - Cable identification system and method of application of power line communication technology - Google Patents

Abstract

The present invention relates to a cable identification system and a method thereof using a power line communication technology in which a cable of a power distribution system can be easily identified by using a radio wave limiting capability for limiting the propagation of a carrier signal in transmitting high frequencies of a power line, Wherein the server modulates the response request message to a high frequency carrier and transmits the response message to the server through the power line, analyzes a response message transmitted from the server to determine a proximity server to identify the cable, The server generates a response message when the response request message is received through the power line, modulates the response message into a high frequency carrier, and transmits the response message to the client via the power line.

Description

Technical Field [0001] The present invention relates to a cable identification system and a method thereof,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cable identification using a power line communication technology, and more particularly, to a power line communication method and a power line communication method for easily identifying a cable of a power distribution system using a radio wave limiting capability for limiting the propagation of a carrier signal, To a cable identification system and a method thereof.

Electricians working at the job site must be aware of the exact electrical configuration, such as phase or cable connections. Accurate identification of cable and phase is a safety-critical issue, and mistakes in choice can have catastrophic consequences for operators and loss of power to connected users. In particular, low voltage connection data (in conjunction with the end user from the MV / LV transformer) is critical for accurate management of the distribution network.

Distribution lines are used to deliver electricity from the plant to the customer. In a typical power distribution system, three-phase power is delivered through a number of substations that raise or lower the voltage to meet customer needs. In addition, the high voltage transmission lines are usually crossed to allow the same physical state for the same phase over the entire line. In addition to crossing, the lines are often grounded. The distribution lines are designed so that the load is balanced, for example, the load at each phase of the three-phase line is the same, but over time, new customers are added, or existing customers are exited, .

Phase and cable decisions need to be made in three - phase, four - wire distribution lines with multiple grounds, but absolute phase and cable decisions are difficult. If there is confusion in the phase on the line and in the cable decision, the load tends to be imbalanced and unbalanced. This phase imbalance can also lead to equipment failure or shortened useful life of the equipment due to power loss, power outage, and even excessive voltage fluctuations. Eventually, significant operational difficulties, such as economic losses, result from the degraded quality of the voltage delivered to the customer. Therefore, the technicians should be able to understand the contents of the field, such as which phase the line conductor should be connected to in phase A, B and C, and which transformer the line conductor should be connected to.

Distribution lines are divided into a number of circuits to supply power to branch transformers or ground-based transformers. Generally, the A, B, and C phase values of the electrical signal at the substation are known, but it becomes increasingly difficult to identify the absolute phase value and cable configuration towards the end of the distribution line. In such a situation, most of the phase identification methods, as disclosed in Non-patent Documents 1 to 5, are based on a comparison between the known phase value of the substation and the unknown phase value of the local site, It has adopted a method to identify the problem.

Information on accurate low-voltage connection data is important not only for transformer load balancing and fault calculation, maintenance work schedules, but ultimately for ensuring quality of electricity supply. It is necessary to determine the correct cable for accurate connection of the distribution system.

Cable identification means choosing one cable from a bundle of cables or finding out cable-to-transformer connections.

Assume that many transformers and distribution lines are arranged along a distance as shown in FIG. An electrician wants to find a transformer or distribution line to connect power lines in the premises. However, it is not easy to find because of many obstacles such as buildings, trees, and hills.

First, we need some explanation of how to identify the cable at the local site. A newly developed cable identification system consists of a current impulse generator and a receiver. The receiver is connected by a clamp to decouple the recognition signal. In the pulse generator, some pulses of a certain type are generated and transmitted on the cable being verified. The transmitted impulse signal causes an electromagnetic field with a definite polarity around the received cable as a flex coupler of the automatically synchronized receiver. Directional clamps combined with parametric monitoring by the receiver allow safe selection of any interference. In other words, when all other cables have the opposite polarity, only one conductor or cable has the correct polarity.

Alternatively, when a direct signal is injected into the transmitter, it analyzes the received signal at the receiver in terms of amplitude-time-phase. Another way is for the central and line devices to communicate the encoded messages over the distribution network.

Bouvrette, Michel, "Telephasing method and system for remotely identifying unknown phases of transmission or distribution lines within an electrical network," US Patent 4626622, 1986 Pomatto, Lawrence A. "Apparatus and method for identifying the phase of a three phase power line at a remote location," US Patent 5510700, 1996 K.E. Martin, et al., "IEEE Standard for Synchrophasers for Power Systems" IEEE Transactions on Power Delivery, vol.13, No.1, pp73-77, Jan. 1998 Apparatus and method for identifying a cable phase in a three-phase power distribution network, Gregory H. Piesinger, US Patent 7,031,859, 2006 "Distribution System Modeling and Analysis"; William H. Kersting; CRC Press, 2002

However, since such conventional techniques use a phase identification method, it is disadvantageous in that the identification of the cable is complicated and unsafe.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above problems occurring in the prior art, and it is an object of the present invention to provide a cable management system, The present invention is directed to a cable identification system and a method thereof that employs a power line communication technology.

It is another object of the present invention to provide a cable identification system and a method thereof that utilize a power line communication technology for easily, safely, and reliably selecting a cable using a cable identification method using power line communication.

In order to achieve the above object, an embodiment of a cable identification system using a power line communication technology according to the present invention is a system in which a client and a server communicate via a power line, the client transmits a response request message to a high frequency carrier And transmits the response message to the server through the power line. The response message transmitted from the server is analyzed to determine a proximity server to identify the cable. The server generates a response message when the response request message is received through the power line Modulates the generated response message with a high frequency carrier, and transmits the modulated response message to the client via the power line.

Wherein the client transmits a response request message and analyzes the received server message to determine a proximity server; Modulates the response request message transmitted from the microprocessor to a high frequency carrier and transmits the modulated request message to the server through the power line, receives and demodulates a message transmitted from the server through the power line, And a power line communication modem for transmitting the power line communication modem.

The server includes a power line communication modem for receiving and demodulating a request message transmitted by the client through the power line, modulating the response message into a high frequency carrier wave and transmitting the modulated response message to the client via the power line; And a microprocessor for generating a response message and transmitting the response message to the power line communication modem when a request message arrives via the power line communication modem.

The microprocessor of the server generates a response message including a server unique number assigned in advance to identify the server.

The microprocessor of the client identifies the server based on the server unique number included in the received server message and determines the closest server based on the delay time (RDT) of the received server message.

Wherein the client and the server are connected on the same power line communication channel on the secondary side power distribution line of the same transformer to perform power line communication.

According to another aspect of the present invention, there is provided a cable identification system using a power line communication technology according to the present invention, wherein a client and a server communicate with each other via a power line,

The server modulates a cable message including identification information capable of periodically identifying a cable of the server through a power line to a high frequency carrier and transmits the modulated cable message to the client,

The client receives the cable message transmitted from the server through the power line, demodulates the received cable message, and identifies the cable by analyzing the identification information included in the demodulated cable message.

According to another aspect of the present invention, there is provided a method of identifying a cable in a system in which a client and a server communicate with each other via a power line, the method comprising the steps of: (a) Generating a response message, modulating the generated response message into a high-frequency carrier, and transmitting the generated response message to the client when the message transmitted from the client is received via the power line while the server is waiting for receiving the message; (b) the client generates a response request message in a transmission wait state, modulates the response request message into a high frequency carrier, and transmits the response request message to the server via the power line; (c) when the client receives the response message through the power line, analyzing the received response message to determine the proximity server.

The server of step (a) generates a response message including a server unique number assigned in advance in order to identify a server when generating a response message.

When the client of the step (c) receives the response message, the client distinguishes the server based on the server unique number included in the received response message, and determines the closest server based on the delay time of the response message .

According to another aspect of the present invention, there is provided a method of identifying a cable in a system in which a client and a server communicate with each other via a power line,

(a) modulating a cable message including identification information capable of identifying a cable of a server through a power line periodically with a high frequency carrier in the server, and transmitting the modulated cable message to the client;

(b) receiving and demodulating a cable message transmitted from the server through the power line at the client;

(c) identifying the cable by analyzing the identification information included in the demodulated cable message at the client.

According to the present invention, there is an advantage that a cable of a power distribution system can be accurately and easily identified by using a radio wave limiting capability for limiting the propagation of a carrier signal in transmitting a high frequency power line.

In addition, according to the present invention, there is an advantage that an easy, safe and reliable cable selection can be realized by using a cable identification method using power line communication.

FIG. 1 is a diagram illustrating a situation in which cable recognition is generally required,
2 is a block diagram of a cable identification system using a power line communication technology according to a preferred embodiment of the present invention.
3 is a diagram illustrating an operation for recognizing a transformer Tr in the present invention,
4 is a diagram illustrating an operation example for recognizing a cable in the present invention,
5 is a time-distance graph of signal transmission in power line communication,
Fig. 6 is a diagram showing a Y-type line segment model of three-phase four-wire grounding in the present invention,
7A and 7B are flowcharts showing a cable identification method using a power line communication technique, in which 7a is a flowchart showing a cable identification method in a client, 7b is a flowchart showing a response message transmission process in a server,
8 is a sample view of a Simullink distribution system model in the present invention,
9 is a voltage waveform at P2 for a carrier signal of 290 kHz, 300 mA,
10 is a voltage waveform diagram at P3 for a carrier signal of 290 kHz, 300 mA,
11 is a voltage waveform diagram at P4 for a carrier signal of 290 kHz, 300 mA.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a cable identification system and method according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of a cable identification system using a power line communication technology according to a preferred embodiment of the present invention.

The cable identification system using the power line communication technology according to the present invention includes a power line 10, a client 20 and a server 30. [ Here, the client 20 means a system used by a user (e.g., an electrician) for cable identification. It is preferable that the client 20 is manufactured in the form of a small terminal so that it is portable and easy to use.

Although only one server 30 is shown in FIG. 2, the present invention is not limited thereto. In actual system implementation, a plurality of servers may be connected to the same power line 10 to implement a system.

The power line 10 means a power cable for power line communication.

The client 20 modulates the response request message into a high frequency carrier and transmits the modulated response message to the server 30 through the power line 10. The server 20 analyzes the response message transmitted from the server 30 to determine a proximity server, .

The client 20 includes a microprocessor 21 for transmitting a response request message and analyzing the received server message to determine a proximity server; Modulates the response request message transmitted from the microprocessor 21 to a high frequency carrier and transmits the modulated request message to the server 30 through the power line 10, A power line communication modem (PLC) 22 for receiving and demodulating the message transmitted from the microprocessor 21, and transmitting the demodulated message to the microprocessor 21; And a power supply unit 23 for supplying driving power to the microprocessor 21 and the power line communication modem 22.

The server 30 generates a response message when the response request message is received through the power line 10, modulates the generated response message into a high frequency carrier, and transmits the response message to the client 20 through the power line 10 It plays a role.

The server 30 receives and demodulates the request message transmitted by the client 20 through the power line 10 and modulates the response message into a high frequency carrier wave and transmits the modulated response message to the client 20 via the power line 10 A power line communication modem (PLC modem) 31 for transmitting; A microprocessor 32 for generating a response message when a request message arrives via the power line communication modem 31 and transmitting the response message to the power line communication modem 31; And a power supply unit 33 for supplying driving power to the microprocessor 32 and the power line communication modem 31.

The microprocessor 32 preferably generates a response message including a server unique number (ID) assigned in advance to identify the server.

In the present invention, it is assumed that the client 20 and the server 30 are connected on the same power line 10 communication channel on the secondary side power distribution line of the same transformer Tr to perform power line communication.

The operation of the cable identification system using the power line communication technology according to the preferred embodiment of the present invention will be described in detail as follows.

First, the present invention utilizes a power line communication technique for cable identification of a distribution system.

Powerline communication technology is required for various applications ranging from home automation to broadband over power lines (BPL). Power line communication (PLC) is one of the technologies used in the advanced metering infrastructure (AMI system). Most powerline communications are limited to one type of wiring, such as in-building wiring within a building. Transformers require a variety of techniques to prevent signal propagation and form a very large network, and are used in a variety of data transmission speeds and frequencies.

The proposed system uses power line communication technology and operates by adding a modulated carrier signal to the wiring system.

As shown in FIG. 2, a cable identification system employing a power line communication technology mainly comprises a client 20 and a server 30. A message is transmitted between the client 20 and the server 30 through the power line communication using the power line 10. [

The power distribution system is designed to transmit AC power at the typical frequency of 50Hz or 60Hz, so the power cable has limited ability to transmit high frequencies. This propagation problem can be a limiting factor in each powerline communication.

The present invention uses this limited capability to identify cables. For cable identification, transformer recognition must first be performed, followed by cable identification.

As shown in Fig. 3 for transformer recognition, the added carrier signal by the client 20 will not pass through the transformer 2 (Tr. 2), so the transmitted signal is transmitted through the transformer 1 (Tr. 1) 3 (Tr. 3). On the other hand, the server 30 on the distribution line connected to Tr. 2 responds to the corresponding response request message, and this response message is also received by the client 20. Then, it can be said that the client 20 and the server 30 are connected on the same power line communication channel on the same power distribution line under the same transformer.

An important issue here is to determine the frequency of the powerline communications. Many countries regulate unshielded wired emissions because they are likely to cause radio transmission. It is therefore recommended to use unlicensed bands or bands below 500kHz.

Next, FIG. 4 shows a method of identifying a cable using three servers having different response messages. When the client 20 sends out one response request message, all the servers 30, 31, and 32 respond with different code messages. Here, the other code is a server unique number (ID) for identifying each server. The client 20 sequentially receives response messages at different times according to the distance between the client 20 and each server.

For example, if the distance between the transformer 2 (Tr. 2) and the server is Lt, the transmission time TT will be Lt / S as shown in the following equation (1). Where S is the propagation speed of the carrier signal on the cable.

Assuming that the client 20 starts sending a response request message at time t0 and receives a response message at time t1 from the nearest server 30, the client 20 receives the response message from the other server 31,32 The other message is received at 't2' and 't3', which are delayed by twice as much as 'TT'. Geographically, the other servers 31 and 32 are located at a distance twice as large as 'Lt'.

For example, when Lt = 100 m and S = 3 * 10 ⁸ m / s, the approximate delay time RDT (= 2 * TT) becomes about 700 μs.

5 shows a time-distance graph of signal transmission.

The operation of the system for identifying a cable using a cable identification system composed of a server and a client based on the above description will be described below.

The microprocessor 21 of the client 20 generates a response request message using the client program and transmits it to the power line communication modem 22 via the interface. The power line communication modem 22 converts the received response request message into a signal modulated with a high frequency carrier wave. Then, the modulated signal is transmitted to the server 30 side via the power line 10.

In the server 30, the power line communication modem 31 connected to the power line 10 receives the response request message modulated on the carrier wave, demodulates it, and transmits the response request message to the microprocessor 32. The microprocessor 32 confirms the received response request message and generates a response message in response thereto. At this time, a response message is generated by adding a server unique number (ID) for identifying itself (server) to the response message. The response message thus generated is transmitted to the power line communication modem 31 through the interface, and is converted into a signal modulated by the high frequency carrier again. Then, the response message modulated by the carrier wave is transmitted to the client 20 side via the power line 10. [

Here, the carrier frequency is 290 kHz and 125 kHz with narrow band modulation of the simple MAC.

The power line communication modem 22 of the client 20 receives the response message transmitted through the power line 10, demodulates it into an original signal, and transmits the response message to the microprocessor 21 as a response message.

The microprocessor 21 identifies the server by the server unique number included in the response message to be transmitted, determines the server closest to the server based on the delay time included in the response message, and identifies the cable based on the determined delay time.

Meanwhile, the above-mentioned cable identification system is a system for transmitting a response request message from a client to a server and analyzing a response message transmitted from the server to identify a cable. In the present invention, It is also possible to transmit a cable message containing identification information through a power line, receive it from a client and demodulate it, and identify the cable through analysis.

Here, the configurations of the client 20 and the server 30 are the same as those of FIG. 2 described above, and therefore, the configuration will be described with reference to FIG.

For example, the server 30 modulates a cable message including identification information capable of periodically identifying the cable of the server 30 through a power line 10 to a high frequency carrier, and transmits the modulated cable message to the client 20. The identification information may be a unique number of the server or a specially predetermined code.

The client 20 periodically receives a cable message transmitted from the server 30 via the power line 10, and demodulates the received cable message. And identifies the cable by analyzing the identification information contained in the demodulated cable message. Here, it is preferable to use the same principle as the cable identification method of the above-described embodiment in order to determine the server by using the unique number or code of the server and to analyze the cable by analyzing the adjacent server.

7A is a flowchart illustrating a method of determining a server closest to the microprocessor 21 in the microprocessor 21.

That is, the client 20 generates a response request message (S12) and transmits the response request message to the server 30 in a transmission waiting state (S11). Thereafter, a response message transmitted from the server is received (S13). Then, it is confirmed whether the message transmission and reception are repeated the predetermined number of times (S14). If not, the procedure repeats the response request message transmission and the response message reception process by increasing the number of attempts by the set number of times (S15) .

If the transmission of the response request message and the reception of the response message are performed a predetermined number of times, the response message is analyzed to determine the neighboring server (S16, S17).

That is, the server is identified based on the server unique number included in the received response message, and the nearest server is determined based on the delay time of the response message, and the power line connected to the server is identified by the cable.

FIG. 7B shows a process of receiving a message and transmitting a message in the server 30. FIG.

When a response request message transmitted from the client 20 is received (S22), a response message is generated in a message reception waiting state (S21), and the generated response message is transmitted to the client 20 via the power line 10 (S23).

Here, the above-mentioned cable identification method is a method of transmitting a response request message from the client to the server and analyzing the response message transmitted from the server to identify the cable . In the present invention, It is also possible to transmit a cable message containing identification information through a power line, receive it from a client and demodulate it, and identify the cable through analysis.

Here, the configurations of the client 20 and the server 30 are the same as those of FIG. 2 described above, and therefore, the configuration will be described with reference to FIG.

For example, the server 30 transmits a cable message including the identification information that can identify the cable periodically server 30 through the power line 10 to the open and modulation to a high frequency carrier the greater Lai gradient 20 . The identification information may be a unique number of the server or a specially predetermined code.

The client 20 periodically receives a cable message transmitted from the server 30 via the power line 10, and demodulates the received cable message.

Then, the identification information included in the demodulated cable message is analyzed to identify the cable. Here, it is preferable to use the same principle as the cable identification method of the above-described embodiment in order to determine the server by using the unique number or code of the server and to analyze the cable by analyzing the adjacent server.

On the other hand, in order to properly apply cable identification technology, some analysis of power line communication is required for distribution lines. Traditionally, three-phase lines have been described as a single-phase, convergent model using the same load and balance line conditions, and the analysis that produces the phase shifts is based on the Kirchhoff voltage law.

Typically, the distribution network consists of three-phase power, circuit breakers, distribution lines, transformers, loads, ground, and so on. Specifically, the distribution network can be depicted as branches extending radially from the substation. Figure 6 shows a simplified model of a distribution line having a plurality of conductors of three-phase four-wire type.

Distribution lines can be modeled as distributed constant circuits through the application of the transmission wave theory model instead of the static model based on Kirchhoff's circuit theory. The power signal through the power line travels according to the electromagnetic field transmission theory. The transmission equation for the power signal is applied to the distribution line as shown in Equation (2) below. The magnitude and phase of the voltage and current on the power distribution line vary with time and place. In addition, the voltage in the power line equation changes depending on the influence of the reflection coefficient along the load impedance Z _L at the end of the line.

Where R, L, G and C are the resistance per unit length (Ω / m), the impedance per unit length (H / m), the conductance per unit length (S / m), the parallel capacitor per unit length )to be.

Balanced three-phase supply voltage (

,

,

) And Y-load impedance (

,

,

), The current (

,

,

) Is flowing along the line. In addition, it is assumed that the power waveform applied to the line is a sinusoidal waveform. The individual phases of the three-phase voltage signals are spaced 120 [deg.] Apart, each having a frequency of 60 Hz. The symbols A, B, and C were used to distinguish three independent phases.

Assume a distribution line with multiple grounded neutral points as shown in FIG. When Kirchhoff's voltage law is applied to a 4-wire grounded neutral circuit, the phase impedance matrix is obtained by Equation (3) below.

Equation (3) can be reduced to a 3 * 3 phase matrix composed of impedances mutually equivalent to magnetism for three phases. In general, the Kron method is used, and the voltage equation in the form of a matrix for wiring is expressed by Equation (4).

In many cases, the analysis of the wiring can be represented by sequence impedance elements such as positive sequence impedance, negative sequence impedance, and zero sequence impedance. The definition of the line-to-ground phase voltage as a function of the line-to-ground sequence voltage is given by Equation (5).

Here, a = 1.0 ∠ 120 °.

The following equation (6) is multiplied to both sides of the equation (4)

Can be switched to the sequence domain by substituting for the phase current definition. Finally, Equation (7) for converting the line-to-ground phase voltage to the sequence voltage is obtained as follows.

Here, the diagonal term of the matrix is the sequence impedance of the line, Z ₀₀ = zero sequence impedance, Z ₁₁ = positive sequence impedance, and Z ₂₂ = negative sequence impedance.

The hyperbolic terms represent the mutual coupling between the sequences. In the ideal state, these non-diagonal terms would be zero, as shown in equation (8) below. To do this, it must be assumed that the lines are crossed. This is common for high-voltage distribution lines. When the lines are crossed, the mutual coupling (non-diagonal terms) between the phases is the same and thus the non-diagonal terms of the sequence impedance matrix are zero.

To represent the other two points on the distribution line, the numbers 1 and 2 were written in subscript form. The voltage at point 1 on the power distribution line is given in the time domain as: < EMI ID = 9.0 >

The voltage at the other point 2 is given by the following equation (10).

To determine the phase at points 1 and 2, the voltage waveform in the time axis needs to be transformed into a signal in the frequency domain. Assuming that only 60Hz frequency components are included, the voltage signal can be represented by magnitude and phase elements. The phasor is represented by a vector with magnitude and phase. Using Euler's formula, the voltage signal waveform is converted to phasor as shown in Equation (11) below.

Digital computers can be used to accommodate various methods for network analysis, and flow calculations, fault current calculations, and EMTP analysis can be considered. In the present invention, MATLAB Simulink software was used. Compared to other software programs, Simulink software has the advantage that it does not require the source code compilation process.

As an example, a Simulink model including multiple transformers and distribution lines is depicted in FIG.

Details of the Simulink model, including power, lines, unbalanced load, transformer, ground resistors, and phase measurement system for phase simulation, are described below.

First, the input source is expressed in terms of internal resistance and internal inductance in terms of power as shown in FIG. A power capacitor capable of sufficiently supplying power to be used in the load is provided. The power is wired in three phases and the supply voltage is sinusoidal. The neutral point is connected to a ground resistance. The power output is provided to the distribution line through a transformer wired to Y or delta (Δ).

In Simulink model loads, various forms can be used, such as constant impedance, constant current load, or constant capacitors. A constant impedance model is a linear load with a series of resistors, inductances and capacitance values at a predetermined frequency. The active power and the reactive power dispersed in the load are characterized by being proportional to the square of the applied voltage. The Simulink model of the constant current load is useful when allocating arbitrary current to each line, and the present invention uses this.

In modeling the transformer, the voltage ratio of the primary voltage and the secondary voltage, and wiring methods can be set. The transformer used in the simulation consists of three single-phase transformers, with Y or Delta wiring available for the primary or secondary coils. In the present invention, a transformer model with internal loss in mind is used depending on internal resistance and inductance. Since recent transformers have very low resistance and voltage drop, the voltage phase shift across a transformer is typically calculated to within ± 5 °.

Ground is modeled to have only one resistive element. The ground resistance is assumed to be 5Ω, which is the standard value for the 22.9kV multiple-ground system.

In the case of distribution lines, the parameters are expressed as symmetrical components (zero, positive, negative).

Using the sample distribution model shown in FIG. 8, a distribution system when a carrier signal of 290 kHz, 300 mA was scanned on a distribution line was analyzed by Simulink.

Under the assumption that the electric signal moves to the light flux, the propagation time necessary for the electric signal to travel a certain distance is obtained. There may be a number of factors that affect the modulation characteristics, such as propagation delay, line length, dispersion parameters, load current, and so on. The length Lt was set to 500 m.

The values of the components used in the simulation of the above equation (7) are as follows.

Zero Phase R0 = 0.23? / Km, L0 = 5.478mH / km, C0 = 0.008? / Km,

Positive Phase R1 = 0.17? / Km, L1 = 1.21 mH / km, C1 = 0.00969? / Km.

Figures 9-11 show voltage waveforms at three different positions P2, P3, P4. To show the characteristics of the modulated signal, a somewhat larger carrier signal of 300 mA was used. It can be seen that the modulated signal in the figure disappears at P4 located on the other transformer.

As a result, for proper application of cable identification, the characteristics of high frequency carrier waves were analyzed with Simulink through multiple transformers. Simulink models and theoretical models are described for analysis. The theoretical simulation shows that the scanned carrier signal is difficult to pass through a higher level transformer.

To prove this invention, the proposed cable identification system is implemented with a simple MAC and narrowband power line communication module with 290 kHz, 125 kHz. Experimental results show that the carrier signal can not be transmitted past a higher level transformer.

Although the present invention has been described in detail with reference to the above embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit of the present invention.

The present invention can be effectively applied to a technique for identifying a cable in a power distribution system using a power line communication technique.

10: Power line
20: Client
21: Microprocessor
22: Power line communication modem
30: Server
31: Power line communication modem
32: Microprocessor

Claims (11)

A system in which a client and a server communicate via a power line,
The client modulates the response request message into a high frequency carrier and transmits the response message to the server through the power line. The client identifies the server based on the server unique number included in the response message transmitted from the server, RDT) to identify the cable through a microprocessor that determines the nearest server,
Wherein the server generates a response message when the response request message is received through the power line, modulates the response message into a high frequency carrier, and transmits the response message to the client through the power line. system.
delete delete delete delete delete delete The server generates a response message, modulates the generated response message into a high frequency carrier, and transmits the response message to the client,
The client generates a response request message in a transmission standby state, modulates the response request message into a high frequency carrier, and transmits the response request message to the server through the power line, thereby identifying a cable in a system in which a client and a server communicate via a power line As a method,
Wherein the client identifies the server based on the server unique number included in the received response message upon receipt of the response message and determines the closest server based on the delay time of the response message How to identify the cable.


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