RU189541U1 - MONITORING DEVICE ELECTRICAL TRANSMISSION LINES - Google Patents

Abstract

The proposed utility model relates to the technique of electrical communication, namely, systems for transmitting information and systems for transmitting high-frequency signals over electrical networks of industrial frequency, and can be used to monitor single and three-phase overhead and cable transmission lines (TL) with voltage up to 35 kV inclusive. To expand the scope of the proposed device, which consists of an attachment device connected to the phase, a transceiver module including a PLC module, as well as Aloha-digital and digital-analog converter, digital filters, built-in amplifier with automatic gain control, modulator-demodulator of analog signal, while the transceiver module is connected to the head module, which in turn is connected to the interface module, a computation module is added to the device to the head module. The computing module performs the function of determining the location of damage to the power line. The operation of this module is based on an algorithm that, based on the analysis of the amplitude-frequency characteristics of the line on each of the three phases, determines the location and nature of the damage with an accuracy of tens of meters.

Description

The proposed utility model relates to the technique of electrical communication, namely, systems for transmitting information, and systems for transmitting high-frequency signals over electrical networks of industrial frequency, and can be used to monitor one and three-phase overhead and cable transmission lines (LEP) up to 35 KV inclusive.

A device for monitoring power lines (“Device for determining the location of damage to power lines and communications”) is a patent for utility model No. 59262 U1, IPC G01R 31/11, containing a computing unit and a probe pulse generator, a receiver and a display unit associated with it.

However, this device is applicable only on straight power lines and is completely unsuitable on lines with a branched topology, which significantly limits the scope of application of the device.

In addition, a device is known for monitoring a line in networks with an extensive topology (“Device for determining the location of damage to power lines with a tree structure” patent for invention No.RU 2511640 G01R 31/08), including determining the distance to the damage site using the method of pulse sensing and disambiguation results of sounding of extensive networks by determining the bit error rate in the information packets of PLC-modules.

However, this device solves only the problem of determining the location of damage to the power line and only in networks with a tree structure, by using the method of pulse reflectometry in combination with PLC-modules in each network node. The device does not apply to power lines with a ring structure, which again limits the scope of the proposed device.

A significant disadvantage of this device is that even with the presence of PLC-modules used to remove the ambiguity of the results of sensing extensive networks, the device lacks the technological information exchange between devices in the network nodes.

In addition, a well-known system of monitoring and diagnostics of power lines with a tree topology based on an “intelligent electro-modem”, which is the prototype of the proposed utility model (Polzunovsky, No. 3/1, 2011, A.N. Zakirov, S.A. Kalabanov, A.V. Karpov, R.I. Shagiev), including a transceiver module, a location module, an attachment device with an electric line and a head module that coordinates the basic modules and the electro-modem interacts with a computer and other peripherals. The system is built using two types of electro-modems. The first type electric modem incorporates both modules and is installed at the beginning of a line in a substation. At the ends of the line, modems of the second type are installed, having in their composition only the transceiver module. Electromodem installed at the substation is the central device in the network. It performs diagnostics of the power line by the method of location sensing (location block), as well as monitoring the line by exchanging data with remote modems using a special protocol stack of the physical and data link levels. Electrical modems are connected to the line according to the “phase-to-ground” scheme via an attachment filter and a coupling capacitor. The presence in the electro-modem of a separate monitoring unit eliminates the disadvantages of the location sensing method associated with the tree topology of distribution power lines (the impossibility of determining which particular branch has caused the damage).

However, this device is intended for distribution networks with a tree topology, which leads to the impossibility of using this system in networks with ring connections, which is a disadvantage, since it limits the scope of the proposed device.

The objective (technical result) of the proposed utility model is to expand the scope and functionality of the device.

The task is achieved by the fact that in the inventive device for monitoring power lines, which consists of an attachment device connected to the phase, a transceiver module including a PLC module, as well as an analog-digital and digital-analog converter, digital filters, an integrated amplifier with automatic gain control modulator-demodulator of the analog signal, while the transceiver module is connected to an attachment device and a head module, which in turn is connected to and terfeysnomu module, wherein the apparatus additionally introduced calculation module connected to the host module.

FIG. 1 shows a block diagram of a transmission line monitoring device; in fig. 2 - Network topology; in fig. 3 - An example of the amplitude-frequency characteristic (AFC) of the source and the branch network without damaging the network; in fig. 4 - Example of frequency response of the network branch in case of damage to the network.

The block diagram of the transmission line monitoring system (Fig. 1) consists of a transmission line monitoring device, indicated in figure 1 by a dotted line (7), which includes an attachment device (1), a transceiver module (2), a head module (3), a computing module ( 4), an interface module (5), as well as a device for collecting and transmitting data (6), two identical additional modules, indicated in FIG. 1 with dashed lines (8, 9), consisting of an attachment device (1) and a transceiver module (2).

The connection device (1) contains a series-connected high-voltage capacitor and a connection filter, in parallel with which a voltage limiter is connected. This module matches the high-frequency output of the PLC-module with the communication channel, simultaneously performing the function of protecting the module from the high voltage of the line.

Transceiver module (2) performs the functions of converting a digital signal into analog and vice versa. This module analyzes the signal received from a similar module on the other side of the line, and then sends a response signal, thereby organizing a communication channel between devices. The transceiver module consists of a PLC module, as well as an analog-digital and digital-analog converter, digital filters, an integrated amplifier with automatic gain control, and an analog signal modulator-demodulator.

The head module (3) is the link between all the modules of the device. It provides interaction between the device modules, and also performs the functions of power management, monitoring failures during operation of the device. The head module consists of a processor, an information collection module, a communication module, a communication module, and a time server.

Computing module (4) performs the function of analyzing the data to determine the location of damage to the power line. The operation of this module is based on an algorithm that, based on the analysis of the amplitude-frequency characteristics of the line on each of the three phases, determines the location and nature of the damage with an accuracy of tens of meters. A compute module can be made of a processor core, static RAM, flash memory, a graphics processor, a network module, debugging and peripheral interfaces.

The interface module (5) is an expansion card that connects to the head module. Depending on the type of terminal devices, a board with the required interfaces (Ethernet, RS-485, RS-232, USB) is selected on board. If necessary, it can act as a switch, allowing you to connect several nodes of a computer network.

The data acquisition and transmission devices (6) can be made in the form of a computer, a measuring device, a terminal of protection and other devices. They are not part of the proposed device, but only serve as a source or receiver of data.

The network topology (Fig. 2) contains transmission line monitoring devices (10-17), and illustrates the possible structure of power lines and connection points for the proposed devices to it.

The main functions of the proposed device are monitoring the state of networks (interruption of transmission lines, interfacial closures and short circuits to ground), data transmission for energy consumption metering systems, quality monitoring and other electric power parameters at all stages of transmission from distribution substations to the end user, the implementation of telemetric transmission tasks data on the state of electrical network equipment and remote control of equipment, the provision of communication channels for the organization of service and commercial data networks.

The device works as follows. The transmitting device (10, Fig. 2) sends to one line the low-voltage, high-frequency (RF) modulated signal in the megahertz range, which is formed on the transmitting module (2, Fig. 1) and is transmitted across the power line. The frequency of sending the signal Δt is 2 * 10 ^-4 s.

At each section of the network, a receiving device (11-17) is installed (FIG. 2), connected to the three phases by means of attachment devices (1) (FIG. 1). The signal is received by the transceiver module (2) (Fig. 1), on the basis of which the amplitude-frequency characteristic of the signal is built on the receiver device and through the head module (3) (Fig. 1), the received data is transmitted to the computing module (4) (Fig. 1) for further processing by a specially developed software algorithm. The essence of the algorithm is as follows:

In the process of signal propagation along the power line, the signal amplitude attenuates and the shape is distorted. The receiving device (11-17), with a specified frequency (presumably 1 time in a period of 0.02 s), captures the received signal and, using software, decomposes the aggregate of harmonic signals into a Fourier series, builds the frequency response at each network segment, selects carrier frequency, and analyzes the data. The amplitude-frequency characteristic (AFC) of the signal depends on the mode of operation of the device (10) (Fig. 2), and is the sum of the harmonic components of different frequencies.

The change in the AFC portrait on any part of an extensive network is caused by the impossibility of direct signal transmission along one of the line phases, which indicates the presence of damage along the line. The high-frequency signal transmission range used in the proposed method amplifies, in comparison with the kilohertz frequency range, the phenomenon of electromagnetic induction, which leads to the appearance of an RF signal on adjacent phases with a similarly shaped portrait frequency response and the same carrier frequency. Consequently, damage to one or two phases of the power line does not prevent the receiving devices from receiving and analyzing the signal.

Data analysis is to assess how much the frequency response portrait has changed, and the carrier frequency in each phase has shifted relative to the previous measurement and relative to the neighboring phases. The following variations are possible:

1. Portrait frequency response has not changed. The carrier frequency in all areas is the same.

In normal operation and line idling in all receiving devices (10-17) (Fig. 2), the signal will have the same carrier frequency in the three phases fmaxN (Fig. 3.) and will differ only in amplitude due to signal attenuation.

2. At one of the sections of the network, the carrier frequency shifted to the area of "zero" frequencies (Fig. 4).

A change in the frequency response of the frequency response of one of the network sections (with respect to the transmitting device) indicates the presence of any damage on the transmission line.

3. At one of the three phases, the carrier frequency shifted to the “zero” frequency range.

In the case of a single-phase short circuit to earth (OZZ), the receiver, a signal is recorded about the difference in carrier frequency between the phases. On one phase, the maximum signal amplitude falls at a frequency of 0 Hz, on the other two the carrier frequencies increase with respect to the normal mode and the idling mode. Similar frequency response and frequency distribution with single-phase transverse asymmetry.

4. On several phases, the carrier frequency has shifted to the “zero” frequency range.

With such types of asymmetry, as a two-phase circuit, a two-phase circuit to earth, two-phase transverse asymmetry, on damaged phases the amplitude of the receiving RF signal corresponds to the frequency - 0 Hz, on the remaining phase, the carrier frequency increases (Fig. 4).

5. Several receivers recorded a decrease in the carrier frequency.

If damage occurs in the area remote to some distance from the receiving devices, both of these devices will receive a modified portrait response. The nearest receiver will detect a decrease in the carrier frequency at the damaged phase compared to the normal mode. The device, remote from the place of damage, will receive equal values of the carrier frequency on all three phases, due to the phenomenon of mutual induction, which is amplified in the megahertz frequency range.

Thus, the location of the fault site with the help of building the frequency response of the power line and the allocation of carrier frequencies can be accurately determined.

The technical result of the power line monitoring device is the expansion of the field of application due to the possibility of using devices in ring networks of both single and three-phase overhead and cable power lines, both low and high voltage (from 0.2 to 35 kV inclusive).

Thus, the proposed device, in contrast to the device of the prototype, due to the implementation of the algorithm for analyzing the frequency response, made in the form of a computational module, the determination of the location of damage is possible even with circular transmission lines.

In addition, the use of a transmitting module based on a high-speed PLC-module, allows you to organize a high-speed communication channel that provides for the collection and transmission of technological information from substations or other technological facilities, in close proximity to which the proposed monitoring device is located. Due to the fact that it becomes possible to use a communication channel to provide access to the Internet, implement video surveillance of objects, IP telephony, the claimed device performs not only the functions of determining the location of damage, but also allows you to organize automation of technological objects remote from the head center. Also an obvious advantage is that the proposed device involves the simultaneous monitoring of all three phases of a cable or overhead power line. For three-phase lines, only transceiver modules are used, connected to the line by means of interconnect devices in the head node of the distribution network. This solution will allow not to interrupt the information exchange, even in case of a breakthrough of two phases out of three, thereby ensuring the smooth operation of the system.

Claims (1)

A power line monitoring device, consisting of an attachment device connected to a phase, a transceiver module connected to an attachment device and a head module, which in turn is connected to an interface module, characterized in that a computation module is additionally inserted in the device and performing the function of analyzing the data received from the transceiver module, on the basis of which the location of the damage to the power line is determined.

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