High-frequency communication via power lines. High-frequency communication systems in modern electric power industry High-frequency processing equipment

The FOX series offers state-of-the-art solutions based on SDH / PDH primary network technologies, designed and tested for harsh environments. No other multiplexer solution provides such a wide range of specialized products - from teleprotection to Gigabit Ethernet using SDH technology and spectral division.

ABB pays special attention to the possibility of product upgrades to protect your investment and offers effective maintenance tools.

The complete communication solution of the FOX series consists of:

• FOX505: Compact access multiplexer with bandwidth up to STM-1.
• FOX515 / FOX615: Access multiplexer with up to STM-4 bandwidth, providing a wide range of user interfaces for data and voice systems. Implementation of teleprotection functions and other features specific to a specific field of application ensure compliance with all data access requirements at the enterprise.
• FOX515H: Complementary to the FOX line and designed for high-speed communications.
• FOX660: Multi-service platform for data transmission systems.

All elements of the FOX515 series are controlled by FOXMAN, ABB's unified SNMP-based network management system. Its open architecture allows for integration with third-party management systems, both higher and lower levels. The graphical network display and point-and-click control make the FOXMAN system ideal for TDM and Ethernet management at the access and data layers.

ETL600 R4 universal digital HF communication system

ETL600 is a modern solution to the problem of providing HF communication over power lines for transmitting voice signals, data and protection commands over high voltage lines. The versatile hardware and software architecture of the ETL600 system makes the choice between traditional analog and future-proof digital RF equipment obsolete and obsolete. Using the same hardware components, the user can select digital or analog operating mode on site with just a few clicks. In addition to ease of use, flexibility of use and unprecedented data transfer rates, the ETL600 system also guarantees unconditional compatibility with the existing technological environment and integrates well into modern digital communications infrastructures.

User benefits

• An economical solution to the communication issue, ensuring reliable control and protection of the power system.
• Reduce costs through a common reserve of hardware and spare parts for analog and digital HF communication systems over power lines.
• Flexible architecture for easy integration into both traditional and modern equipment.
• Reliable transmission of protection signals
• Efficient use of limited frequency resources through flexible choice of transmission bandwidth.
• A fallback solution for selected mission-critical communications that are typically delivered over broadband communications

Connection filter MCD80

Modular MCD80 devices are used to connect the leads of an HF communication device such as the ABB ETL600 through a capacitive voltage transformer to high voltage lines.

The MCD80 filter provides optimum impedance matching for the RF link output, frequency separation and safe isolation of 50/60 Hz mains frequency and transient voltages. It is configurable for single and multiphase communication with high pass or bandwidth filtering. MCD80 devices comply with the latest IEC and ANSI standards.

The main advantages of the MCD80 filters:

• Designed to work with any type of HF communication equipment
• The entire line of filters: broadband, bandpass, crossover, "phase-phase" and "phase-ground"
• Highest possible bandwidth selection (according to customer specification in 1kHz steps)
• Possibility of connection to both coupling capacitors and voltage transformers
• Wide range of connection capacities 1500pF-20000pF
• Possibility of rebuilding at the installation site when changing the connection capacitance within the operating range of capacities (for example, when replacing capacitors with voltage transformers)
• Low passband insertion loss (less than 1dB)
• Parallel connection of up to 9 terminals with a power of 80 W according to the phase-to-ground scheme and up to 10 terminals according to the phase-phase scheme is possible
• Integrated single-pole disconnector (earthing switch)

HF interceptors for VL-DLTC

There are two types of DLTC surge arresters available for the protection of HF-type surge arresters.

Small and mid-sized HF tractors are equipped with standard ABB Polim-D surge arresters without arc arrestors.

Large arresters are equipped with ABB MVT arresters, which do not have an arc arrestor and are specially designed for use with ABB arresters. They use the same highly nonlinear metal oxide varistors (MO arresters) as station arresters.

The internal leakage of the MO restrictor is taken into account when designing the tuner. ABB Metal Oxide Surge Arresters are specially designed for use in the high electromagnetic fields that are often found in HF line interrupters. In particular, they do not contain unnecessary metal parts, in which the magnetic field can induce eddy currents and cause an unacceptable increase in temperature. Modification of the metal oxide surge arresters for the operating conditions of line arresters was necessary because ABB manufactures such devices for stations and is fully aware of the problems that arise in practice. Surge arresters used in line arresters have a rated current of 10 kA.

Features and Benefits

Principal Advantages of DLTC HF Interceptors

Information from the site

A communication channel is a collection of devices and physical media that transmit signals. With the help of channels, signals are transmitted from one place to another, and also transferred in time (when storing information).

The most common devices that make up a channel are amplifiers, antenna systems, switches and filters. A pair of wires, a coaxial cable, a waveguide, a medium in which electromagnetic waves propagate are often used as a physical medium.

From the point of view of communication technology, the most important characteristics of communication channels are the distortions to which the signals transmitted through it are subjected. Distinguish between linear and non-linear distortions. Linear distortion consists of frequency and phase distortion and is described by the transient response or, equivalently, the complex gain of the channel. Harmonic distortion is given by a nonlinear relationship that indicates how a signal changes as it travels through a communication channel.

A communication channel is characterized by a collection of signals that are sent at the transmitting end and signals that are received at the receiving end. In the case when the signals at the input and output of a channel are functions defined on a discrete set of argument values, the channel is called discrete. Such communication channels are used, for example, in pulsed operating modes of transmitters, in telegraphy, telemetry, and radar.

Several different channels can use the same technical communication line. In these cases (for example, in multichannel communication lines with frequency or time division signals), the channels are combined and disconnected using special switches or filters. Sometimes, on the contrary, one channel uses several technical communication lines.

High frequency communication (HF communication)is a type of communication in electrical networks, which involves the use of high-voltage power lines as communication channels. An alternating current with a frequency of 50 Hz flows through the wires of the power lines of electric networks. The essence of the organization of HF communication is that the same wires are used as signal transmission over the line, but at a different frequency.

The frequency range of HF communication channels is from tens to hundreds of kHz. High-frequency communication is organized between two adjacent substations, which are connected by a power line with a voltage of 35 kV and above. In order to get to the buses of the substation switchgear, and the communication signals to the corresponding communication sets, high-frequency traps and communication capacitors are used.

The HF trap has a low resistance at the power frequency current and a large resistance at the frequency of the high-frequency communication channels. Coupling capacitor - on the contrary: it has high resistance at a frequency of 50 Hz, and at the frequency of the communication channel - low resistance. Thus, it is ensured that only 50 Hz current reaches the substation buses, and only signals at high frequency to the HF communication set.

To receive and process HF communication signals at both substations, between which HF communication is organized, special filters, signal transceivers and sets of equipment are installed that perform certain functions. Below we will consider what functions can be implemented using HF communication.

The most important function is the use of the HF channel in relay protection and automation devices of substation equipment.The HF communication channel is used in the protection of 110 and 220 kV lines - phase-differential protection and directional-high-frequency protection. At both ends of the transmission line, sets of protection are installed, which are connected to each other via an HF communication channel. Due to its reliability, speed and selectivity, protection using the HF communication channel is used as the main for each 110-220 kV overhead line.

The channel for transmitting signals of relay protection of power lines (PTL) is called relay protection channel... Three types of HF protection are most widely used in relay protection technology:

filter directional,

remote with HF blocking,

differential phase.

In the first two types of protection, a continuous HF blocking signal is transmitted via the HF channel with an external short circuit, in the phase differential protection, HF voltage pulses are transmitted through the relay protection channel. The duration of pulses and pauses is approximately the same and is equal to half the period of the power frequency. In the event of an external short circuit, the transmitters located at both ends of the line operate at different power frequency half cycles. Each of the receivers receives signals from both transmitters. As a result, in the event of an external short circuit, both receivers receive a continuous blocking signal.

In the event of a short circuit on the protected line, a phase shift of the manipulating voltages occurs and time intervals appear when both transmitters are stopped. In this case, an intermittent current appears in the receiver, which is used to create a signal acting to open the breaker of this end of the protected line.

Typically, the transmitters at both ends of the line operate on the same frequency. However, on long-distance lines, relay protection channels are sometimes carried out with transmitters operating at different HF or at frequencies with a small interval (1500-1700 Hz). Working at two frequencies makes it possible to get rid of the harmful effects of signals reflected from the opposite end of the line. Protection relay channels use a dedicated (dedicated) RF channel.

There are also devices that, using the HF communication channel, determine the location of damage to power lines. In addition, the HF communication channel can be used to transmit signals, SCADA, ACS and other systems of APCS equipment. Thus, through the high-frequency communication channel, it is possible to control the operating mode of the substation equipment, as well as transmit commands to control the switches and various functions.

Another function is telephone function... The HF channel can be used for operational negotiations between adjacent substations. In modern conditions, this function is not relevant, since there are more convenient ways of communication between the service personnel of facilities, but the HF channel can serve as a backup communication channel in the event of an emergency, when there will be no mobile or landline telephone communication.

Power line communication channel - a channel used to transmit signals in the range from 300 to 500 kHz. Various schemes for switching on the communication channel equipment are used. Along with the phase - earth scheme (Fig. 1), which is most common due to its economy, the following schemes are used: phase - phase, phase - two phases, two phases - earth, three phases - earth, phase - phase of different lines. The HF trap, the coupling capacitor and the connection filter used in these circuits are equipment for processing power lines for organizing HF communication channels along their wires.

Figure: 1. Block diagram of a simple communication channel over a power transmission line between two adjacent substations: 1 - HF trap; 2 - coupling capacitor; 3 - connection filter; 4 - HF cable; 5 - device TU - TS; c - telemetry sensors; 7 - telemetry receivers; 8 - relay protection devices and / or teleautomatics; 9 - automatic telephone exchange; 10 - ATS subscriber; 11 - direct subscribers.

Line processing is needed to obtain a stable communication channel. Attenuation of the HF channel along the processed power lines is almost independent of the line switching scheme. In the absence of processing, communication will be interrupted when disconnecting or grounding the ends of the transmission line. One of the most important problems in communication over power lines is the lack of frequencies due to the low crosstalk between the lines that are connected through the substation buses..

HF channels can be used to communicate with operational field teams that repair damaged power lines and repair damage to electrical installations. For this purpose, special portable transceivers are used.

The following HF equipment is used, connected to the processed power line:

combined equipment for telemechanics, automation, relay protection and telephone channels;

specialized equipment for any one of the listed functions;

long-distance communication equipment connected to the power transmission line through a connection device directly or with the help of additional blocks for frequency shift and increasing the transmission level;

equipment for impulse control of lines.

The digital HF communication system MC04-PLC is designed to organize telemechanics (TM) channels, data transmission (PD) and telephone channels (TF) through high-voltage power lines (PTL) of the 35/110 kV distribution network. The equipment provides data transmission over a high-frequency (HF) communication channel in the 4/8/12 kHz band in the 16-1000 kHz frequency range. The connection to the power transmission line is carried out according to the phase-ground scheme through the coupling capacitor and the connection filter. The connection of the high-frequency end of the equipment to the connection filter is unbalanced and is performed with one coaxial cable.

The equipment is manufactured with a spaced and adjacent location of the transmission and reception bandwidths.

Functionality:

Number of HF channels 4 kHz wide - up to 3;
channel mode: analog (frequency division) and digital (time division);
modulation of low-frequency digital stream - QAM with division into 88 OFDM subcarriers;
HF spectrum modulation - amplitude with the transmission of one sideband of AM SSB;
adapting the bit rate of a digital stream (CPU) to a changing signal-to-noise ratio;
telephony interfaces: 4 ‒ wired 4W, 2 wired FXS / FXO;
the number of telephony channels in each HF channel - up to 3;
conversion of ADASE signaling into subscriber signaling FXS / FXO;
dispatching and subscriber connection according to the ADASE protocol on one TF channel;
digital interfaces TM and data transmission: RS232, RS485, Ethernet;
control and monitoring interface - Ethernet;
built-in analyzer of RF path transmission / reception levels, error and temperature meter.
registration of faults and alarms in non-volatile memory;
digital re-reception - transit of channels at intermediate substations without quality loss;
monitoring - MC04 program ‒ Monitor: configuration, setting, diagnostics;
remote monitoring and configuration via built-in HF service channel;
SNMP support - when equipped with the S ‒ port network module;
radial and tree-like monitoring schemes for remote semi-sets;
power supply: mains ~ 220 V / 50 Hz or constant voltage 48/60 V.

Main settings
Operating frequency range 16 - 1000 kHz
Working bandwidth 4/8/12 kHz
Rated peak RF power 20/40 W
Maximum CPU transfer rate in 4 kHz bandwidth (adaptive) 23.3 kbps
The depth of AGC adjustment with an error rate of no more than 10–6 is not less than 40 dB.
Allowable line attenuation (including interference) 50 dB

Power consumption from a 220 V or 48 V power supply network - no more than 100 W.
The overall dimensions of the block are 485 * 135 * 215mm.
Weight no more than 5 kg.

Terms of Use:

- ambient temperature from +1 to + 45 ° С;
- relative humidity up to 80% at a temperature of plus 25 ° С;
- atmospheric pressure not lower than 60 kPa (450 mm Hg).

Equipment design and composition:

The digital three-channel HF communication system MC04-PLC includes two 19-inch units 3U high, into which the following functional and structural units (boards) are installed:
IP01− power supply, mains input 220V / 50Hz, output + 48V, -48V, + 12V;
IP02– power supply unit, input 36 ... 72V, output + 48V, -48V, + 12V;
MP02 - multiplexer of TM, PD, TF channels, G.729 codec, digital echo canceler;
MD02 - modulation / demodulation of the CPU into an analog RF signal, monitoring and control;
FPRM - linear transformer, attenuator and 4-loop PRM filter, PRM amplifier;
FPRD - 1/2 − x PRD loop filter, high impedance outside the PRD band;
UM02 - power amplifier, digital indication of TRD levels, alarm indication.
TP01 - transit of the content of the HF channel between the blocks, installed in place of the MP02 boards.

Ordering information

The number of MP02 boards corresponds to the number of basic HF channels with a 4 kHz band, configurable on the MD02 board - from 1 to 3. In case of transit of one of the HF channels between the blocks at the intermediate substation, a TP01 transit board is installed in place of the MP02 board, which provides reception / transmission of HF content channel without conversion to analog form.
The block has two main versions in terms of the peak power of the RF signal envelope:
1P - one UM02 amplifier and one FPRD filter are installed, the RF signal power is 20 W;
2P - two UM02 amplifiers and two FPRD filters are installed, the RF signal power is 40 W.

Block designation includes:
- the number of used HF channels 1/2/3;
- performance according to the peak power of the RF signal envelope: 1P - 20 W or 2P - 40 W;
- types of user joints of each of the 3 x HF channels / boards MP-02 or board TP01;
- supply voltage of the unit - mains ~ 220 V or constant voltage 48 V.
By default, the MP-02 board has digital interfaces RS232 and Ethernet, which are not indicated in the block designation .

To transfer information between protections and automation at the ends of the high-voltage line, a channel is used, created for high-frequency currents according to the "phase-to-earth" connection scheme.

As part of the path, one phase of the operating overhead line is included, which is connected to the ground through the coupling capacitors at the substations to create a closed loop for HF currents.

Most often, two remote phases "A" and "C" are used on the line for transmission of commands of frequency No. 1 through one of them from the substation, and reception on frequency No. 2 through the second.

The structure and purpose of the HF communication channel... Transmitters and receivers of high frequency signals are installed at each substation. In this case, the modern equipment of HF transceivers is made on the microprocessor base of ETL640 v.03.32 terminals by ABB.

To process signals at each frequency, a separate transceiver is manufactured. Therefore, for one substation, 2 sets of terminals are required, configured to simultaneously receive and transmit signals on different phases of the overhead line.

The connection of the HF transceiver to the overhead line is handled by special equipment that separates high voltage from low-current equipment and creates a highway for transmitting HF signals. It is completed with:

High voltage coupling capacitor (CS);
- connection filter (FP);
- high-frequency minelayer (VZ);
- HF cable.

The purpose of the high-voltage coupling capacitor is to reliably isolate from the ground the power transported along the overhead line with an industrial frequency and pass high-frequency currents through itself.

In the photograph of the line under consideration, there are 3 capacitors with phase converters in each phase. They are used to communicate with far-end equipment to:

1. Transmission of commands RZ and PA;
2. Reception of RZ and PA commands;
3. Work of HF equipment of communication service.

To separate the HF signal from the high-voltage equipment of the substation, an HF trap is mounted in the phase conductor of the high-voltage overhead line. which limits the amount of RF signal loss through parallel circuits.

Power-frequency currents pass well through it and high-frequency currents are not passed. The VZ consists of a reactor (power coil), passing the operating current of the line, and adjustment elements connected in parallel with the reactor.

To match the parameters of the input impedances of the HF cable and line, a connection filter is used, which is performed by a model of an air transformer with taps from the windings, which allows making the necessary adjustments. The RF cable connects the coupling filter to the transceiver.

High frequency transceivers (ETL640), purpose... Transceivers of ETL640 type (PRM / PRD) are designed to transmit and receive RF signals in the form of commands generated by relay protection (RP) and emergency control equipment (PA) to the opposite end of the overhead line.

HF channel serviceability check... The complex equipment of the HF transmission path is located at distances of hundreds of kilometers and requires monitoring and maintaining its integrity. ETL640 transceivers at the ends of the overhead line constantly in normal operation exchange (transmit / receive) signals of the control frequency.

When the signal decreases in magnitude or changes in its frequency beyond the permissible limits, a malfunction alarm is triggered. After the restoration of operability, the transceiver automatically returns to normal operation.

Signal exchange... Signals are transmitted and received at dedicated frequencies, for example:

Complex on phase “A”: Тх: 470 + 4 kHz, Rx: 474 + 4 kHz;
- complex on phase “C”: Тх: 502 + 4 kHz, Rx: 506 + 4 kHz.

ETL640 equipment is designed for round-the-clock continuous operation in heated substations.

Reception and transmission of commands... Terminals No. 1 and No. 2 of ETL640 complexes receive and transmit 16 commands each from RZ and PA.

ETL640 Transceiver Commands... Typical commands of the transceiver of any ETL640 complex can look like:

1. Disconnection of 3 phases of the 330 kV overhead line from the far end of the overhead line without control, with the prohibition of TAPV and start-up from the breaker failure protection or ZNR complex No.… REL-670;

2. Disconnection of 3 phases of the 330 kV overhead line from the far end of the overhead line with monitoring by measuring devices Z3 DZ and the 3rd stage of NTZNP complex No.… REL670 protection without prohibiting TAPV and starting from the factor of 3-phase shutdown of complex No.… REL protections;

3. Teleacceleration of DZ with action on one or 3-phase shutdown of 330 kV overhead line from the far end of the overhead line, with control of parameters of stage Z3 DZ of complex No.… protection REL670 with OAPV / TAPV and starting from stage Z3 DZ of complex No.… protection REL- 670;

4. Teleacceleration of NTZNP with action on one or 3-phase shutdown of 330 kV overhead line from the far end of the overhead line with control of parameters of stage Z3 of NTZNP of complex No.… protection REL670 with OAPV / TAPV and start-up from a measuring device of 3rd stage NTZNP of complex No.… protection REL670 ;

5. Fixing the disconnection of the line from its side of the overhead line and acting in the AFOL logic circuit of the complex No.… protection of relay protection and automation. Start from the output relay of the AFOL logic circuit of complex No.… protection of relay protection and automation devices when the line is disconnected from its side;

6. III stage of OH, acting on launch:
- 5th command of AKAP prd 232 kHz overhead line No.…;
- 2nd command of AKPA prd 286 kHz overhead line No. ...;
- 4th team ANKA prd 342 kHz overhead line No.….

7. Fixation of the connection of the line from its side and action in the AFOL logic circuit of the complex No.… protection of relay protection and automation devices of overhead lines with start-up from the output relay of the AFOL logic circuit of the complex No.

8. Start from the 1st stage of the SAPAH scheme ... with the start:
- 6th team ANKA prd 348 kHz overhead line No. ...;
- 4th command of AKAP prd 122 kHz overhead line No.….

9. 3rd stage of load shedding with action ...

Each team is formed for the specific conditions of the overhead line, taking into account its configuration in the electrical network and operating conditions. RF output relays and switching devices are located in a separate cabinet.

Overhead line signaling circuits... Terminal alarms. On the front panel of the terminals there are 3 LEDs reflecting the state of the REL670 device itself and 15 LEDs indicating the operation of protections, faults and the state of operational switches.

LEDs of terminals REL670 (protection of the 1st and 2nd complexes) and REC670 (automatic equipment and CBFP of the 1st and 2nd complexes B1 and B2) of the first six numbers are colored red. LEDs numbered 7 to 15 are yellow.

LEDs for status indication. 3 LED indicators “Ready”, “Start” and “Trip” are inserted above the LCD block of terminals REС670 and REL670. They light up in different colors to indicate different information. The green light indicates:

Operation of devices - steady glow;
- internal damage - by flashing;
- no power supply of the operating current - by dimming the color.

The yellow indicator color means:

Emergency recorder start - steady glow ;;
- finding the terminal in test mode - accompanied by blinking.

The red color of the indicator indicates the issuance of an emergency shutdown command (steady light).

REС670 terminal LED signaling table

Alarm reset and test... Resetting the alarm, counters for the reception and transmission of HF commands and information on the DZ and NTZNP zones for the terminal is made by pressing the SB1 button (alarm reset) on the front side of the cabinet.

To test the LEDs of REL670 (REС670) terminals, press and hold the SB1 button for more than 5 seconds.

General panel light signaling... On the front side of the REС670 cabinets there are lamps:
- HLW - works of automatic reclosure, ZNF, UROV;
- HLR2 - malfunction of the automation and breaker failure protection V-1 or V-2.

On the front side of REL670 cabinets there are lamps:
- HLW - protection work;
- HLR1 - protection complex disabled;
- HLR2 - malfunction of protection complexes.

On the front side of ETL cabinets there are alarm lamps:
- HLW1 - ETL malfunction of the 1st complex;
- HLW2 - ETL malfunction of the 2nd complex.

Prospects for the development of overhead power transmission line equipment... Time-tested air circuit breakers for high-voltage transmission lines are gradually being replaced by modern gas-insulated designs, which do not require constant operation of powerful compressor stations to maintain air pressure in tanks and air lines.

Bulky analog relay protection and automation devices for high-voltage equipment, which require close attention from the maintenance personnel, are being replaced by new microprocessor terminals.