Government "HF communication" during the Great Patriotic War

P. N. Voronin

Government communications play an important role in the management of the state, its Armed Forces, in socio-political and economic life. Its foundation was laid in 1918, when the Soviet Government moved to Moscow. Initially, a manual communication switchboard for 25 numbers was installed in Moscow, then it was expanded and subsequently replaced by an automatic telephone exchange.

Long-distance government communication (in memoirs and works of art it is called "HF communication") was organized in the 30s as an operational communication of state security agencies. It ensured a certain secrecy of negotiations, and therefore the heads of the highest government bodies of the state and the Armed Forces also became its subscribers. In May 1941, by order of the Council of People's Commissars of the USSR, this connection was defined as "Government HF Communication" and the corresponding "Regulation" was approved. In accordance with the accepted terminology, "HF communication" can be attributed to one of the secondary networks of the EACC and must meet additional requirements for the protection of transmitted information, reliability and survivability. However, it was not possible to fully realize these requirements before the start of the Great Patriotic War. As a means of controlling the Armed Forces in a combat situation, HF communications turned out to be unprepared.

The complication of the situation at the beginning of 1941 was felt by the increasing number of tasks for organizing high-frequency communications for large associations and formations of the Red Army in the border zone. The night of June 21-22 found me doing one of these tasks. At about 4 o'clock in the morning, a duty technician from Brest called and said that the Germans had begun shelling the city. The evacuation has begun. What to do with the HF station equipment? It was instructed to contact the local leadership and act on their instructions, but under all conditions to dismantle and remove the classified equipment. Then such calls came from Bialystok, Grodno and other cities located along the western border. Thus began the war, which immediately set a number of urgent tasks.

In view of the possible bombardment by the enemy of Moscow, it was necessary to urgently transfer the Moscow HF station to a protected room. A room was allocated on the Kirovskaya metro platform. The station was closed to passengers. Installation was carried out on their own. The work was complicated by the fact that it was necessary to transfer the existing equipment without interrupting the operation of the RF station. We didn't have backup equipment.

Similar work was carried out by the People's Commissariat (NC) of Communications. The equipment of the telegraph, the long-distance station was transferred to protected premises. The work was headed by I. S. Ravich (at that time the head of the Central Administration of Trunk Communications). We worked closely with him. The channels necessary for HF communications were supposed to be received only from secure NK communication nodes.

The general unpreparedness of means of communication for war immediately affected. The entire network of the country was based on air lines, extremely susceptible to the influence of climatic conditions, and with the deployment of hostilities and destruction by the enemy both by air bombing and sabotage groups. To destroy multi-wire communication lines, the Germans even used special bombs "with hooks". Falling, such a bomb caught on wires with hooks and exploded, destroying the entire bundle of wires at once.

There were also serious shortcomings in the construction of the long-distance communication network used. It was created according to a strictly radial principle. There were no ring lines of communication and bypass directions, no reserve communication centers were prepared, protected from enemy bombing, and even the entrances to Moscow of the main long-distance lines were not ringed. In the event of the destruction of one of them, it was impossible to switch the communication lines to another direction. The Communications Commission decided to urgently build in September 1941 a bypass ring communication line around Moscow along the Lyubertsy-Khimki-Pushkino-Chertanovo highway. In 1941 it was a ring about 20 km from Moscow. NK communications carried out other work to improve the reliability of the long-distance network.

The task was to provide high-frequency communication with the fronts, and after the battle of Moscow - with the armies. A number of questions immediately arose and, first of all, who will build communication lines and operate them, how to provide front-line HF stations with communication equipment - sealing equipment, switches, batteries, classified communications equipment (ZAS) and other equipment adapted to work in the field .

The first issue was resolved quickly. The State Defense Committee (GKO) ordered the NC Communications and the NC Defense to build and maintain government communications lines. But, as experience has shown, this was not the best solution. Communications NK had overseers to maintain the lines - one for tens of kilometers. With massive damage to overhead lines as a result of hostilities, air raids and destruction by enemy sabotage groups, it was physically impossible to quickly repair damage and ensure uninterrupted communications.

Signalmen of the NK Defense were busy servicing the lines of command and control and also could not focus on the lines of Government communications. As a result, the Government Communications worked unstably at certain moments, which led to fair complaints from subscribers. After each complaint, analyzes began, clarification of the reasons, mutual accusations. Who is guilty? The matter reached the top leadership of the NKVD, the NK Communications and the NK Defense. A radical solution to this issue was needed.

In the Department of Government High-Frequency Communications of the NKVD, it was decided to create a line-operational service, for which to form 10 line-operational companies, then 35 more. Government communications began to work more steadily. But already during the battle near Moscow, when our troops began to advance and the headquarters of the fronts and armies went forward, difficulties arose with the construction of communication lines.

This issue became especially acute in 1942, when the Germans approached the Volga and began to encircle Stalingrad. I remember one of the autumn evenings in 1942. The Germans furiously rushed to the city. The fighting went on near approaches. The front headquarters was located in a shelter on the right bank of the Volga. Communication with the front was interrupted due to the increased bombardment of communication lines. The line units of the Government Communications made heroic efforts to restore the lines, but the enemy bombed, and communication was again broken. Bypass lines were also broken. At this time, I.V. Stalin needed a connection with the Stalingrad Front. A. N. Poskrebyshev, Stalin's assistant, called me and asked what to report to him - when there would be a connection. I answered - in 2 hours (in the hope that during this time it will be possible to restore the line). I contacted our unit and received an answer that the bombing had intensified. He gave the command to make a "temporary hut" - to lay the PTF-7 field cable along the ground. After 2 hours, Poskrebyshev called again. I informed him that it would take another 40 minutes. After 40 minutes, Poskrebyshev offered to personally report to Stalin when there was a connection. But at this time the line was restored. Stalin spoke with the headquarters, and a personal report was not required. Soon, People's Commissar of Internal Affairs Beria and Deputy People's Commissar of Defense People's Commissar of Communications I. T. Peresypkin were summoned to Stalin. Stalin expressed great displeasure that there was no stable connection with Stalingrad and recalled that back in 1918 he had a reliable connection with Lenin while on the Tsaritsyn front.

It was instructed to make proposals providing for the responsibility of one body for the unconditional reliability of communications. Such proposals have been developed. The Decree of the State Defense Committee of January 30, 1943 was issued. Government communications troops were created, whose task was to ensure the construction, maintenance and military protection of government communications lines from the Headquarters of the Supreme High Command to the fronts and armies. Other lines running across the country to the republics, territories and regions, used for Government communications, remained in the service of NK communications.

In the NKVD, the Directorate of the Government Communications Troops was created. It was headed by P. F. Uglovsky, who had previously been the head of communications of the border troops. The head of the line service in the Department of Government Communications K.A. Aleksandrov, a major lineman, became his deputy. At the fronts, Departments of Government Communications were created, to which subdivisions of the Government Communications troops were subordinated - separate regiments, battalions, companies. It seems somewhat strange the decision to create in the NKVD two units in charge of government communications - the Department and the Directorate of Troops. However, this was dictated by the specifics of the work of the state security agencies: there were operational units and troops performing specific military tasks at the direction of the operational agencies.

Like this structure, the NKVD had an operational body - the Department of Government Communications, which was in charge of the organization of communications, its development, technical equipment, station service, issues of maintaining secrecy - and troops that built communication lines, ensured their uninterrupted operation and guarded in pairs and secret ambushes in vulnerable places, excluding the possibility of connecting to eavesdropping lines, prevented possible sabotage.

The department and the Directorate of Troops worked in close contact throughout the war, and there were no misunderstandings in their relationship. They united in 1959; the structure of the Government Communications received a logical conclusion. The organs and troops were capable of comprehensively fulfilling the tasks of organizing and providing communications in difficult conditions of a combat situation.

Communication was organized along "axes" and directions. The center line was drawn to the headquarters of the front. As a rule, they tried to build two center lines along different routes, a direction was laid to the armies - one line of communication. Two chains were suspended on it: one was compacted by high-frequency equipment, and the other, a service one, was intended for communication with service posts.

In the army sectors, during the construction of communication lines, we often had contact with signalmen from the NK Defense. They pulled one line, which was used for compaction, and the "middle point" was handed over to army signalmen for telegraph communications using the Baudot system. HF communication was organized at the main command post (CP), reserve (ZKP) and advanced (PKP) points. When the front commander left for the troops, he was accompanied by an officer of the Government Communications with the ZAS equipment. HF communication was organized at the location of the commander, taking into account the available army communication lines or NK communication lines.

The baptism of fire of the troops of the Government Communications received in the battle on the Oryol-Kursk Bulge, where five fronts were operating simultaneously and several dozen HF stations were deployed. Signalers successfully coped with the assigned tasks, ensuring continuous communication of the Stavka with all fronts, armies and two representatives of the Stavka - G. K. Zhukov and A. M. Vasilevsky, who had their own HF stations.

After the Battle of Oryol-Kursk, the troops began a swift offensive, freeing our territories from the German invaders. The speed of the offensive of combined arms armies reached 10-15 km per day, and tank armies - up to 20-30 km. At such a pace, the troops did not have time to build permanent air lines. They had to be armed with the so-called cable-pole lines, which were deployed as temporary troops during the rapid advance of the troops and were subsequently replaced by permanent ones if it was necessary to maintain this direction. This is how the line service was created.

Issues and technical equipment of front-line and army high-frequency communication stations were also resolved. In the Government Communications, for the organization of high-frequency channels, the system of multiplexing in the spectrum of 10-40 kHz of the SMT-34 type, adopted at that time on the long-distance network of NK communications, was used. It was purely stationary equipment. Racks with a height of 2.5 m weighed more than 400 kg. By car, the rack could be transported by laying it on its side. She couldn't stand any shock. Often, after transportation, it took days to restore the installation. There were also no switches, batteries, block stations and other equipment adapted to field conditions. Everything had to be recreated.

The only base for the production of long-distance communication equipment at that time was the workshop at the Krasnaya Zarya plant in Leningrad. But by the end of 1941, Leningrad was under blockade. Emergency measures were taken to evacuate this workshop to Ufa, where plant No. 697 for the production of long-distance communication equipment and a research institute were established.

Thanks to the hard work of teams headed by prominent specialists A. E. Pleshakov and M. N. Vostokov, the SMT-42 equipment was created (in the spectrum of 10-40 kHz), and then SMT-44 (field versions of the SMT-34 equipment; height - 60 cm, weight - 50 kg). It was convenient for the rapid deployment and collapse of RF stations, and withstood shaking during transportation. The equipment of the low frequency frequency band was also developed in the spectrum up to 10 kHz, and a fourth channel was added to the equipment of the SMT in the spectrum over 40 kHz, switches and ZAS equipment were created in the field. For the creation of this complex, the authors were awarded the State Prize. Government communications received a complete set of communications equipment in the field, which made it possible to quickly resolve issues of organizing high-frequency communications.

An attempt was made to back up wired communication with the fronts by radio. At that time, only the KB band could be used for radio communication. The RAF and PAT stations produced by the industry were taken. But they did not find wide application. The ZAS equipment used on radio channels made high demands on the quality of the channel, which was difficult to achieve on KB lines. In addition, subscribers, warned that they were provided with communication by radio, often refused to speak. I remember such a case. After the end of the war, a peace conference was held in Paris. The Soviet delegation was headed by V. M. Molotov. We organized wire communication to Berlin via our own communication lines, and the Americans provided the line from Berlin to Paris. While we were having open conversations, the connection worked perfectly, as soon as the ZAS was turned on, the connection stopped. We also provided for redundancy by radio, using stationary means of radio communications of the NC communications. But Molotov refused to speak on the radio, saying that he must recognize the voice of the subscriber with whom he speaks. With the ZAS equipment that was used, this was difficult to achieve. I had to quarrel with the Americans and achieve stable operation of wired communications.

A description of the activities of the Government Communications during the Great Patriotic War will not be complete if we do not dwell on some of the most significant operations and activities.

When Leningrad was blockaded by the Germans at the end of 1941, the question of high-frequency communication with the Leningrad Front and the city became acute. NK Communications organized communication by radio. We could not use this connection due to the lack of appropriate ZAS equipment. A line was needed. NK Communications and NK Defense decided to urgently lay the cable in the only possible direction - along the bottom of Lake Ladoga. The laying was already under fire from the enemy. As a result, a wired air connection was organized with Leningrad through Vologda to Tikhvin, then by cable to Vsevolozhskaya, then again by air to Leningrad. The Headquarters had a stable high-frequency connection with Leningrad throughout the war.

By the summer of 1942, the Germans had recovered from the defeat near Moscow, and an offensive began in the southern direction. The Voronezh Front was created. I flew with a group of employees to Povorino, where the headquarters of the Voronezh Front was supposed to move. Soon the first deputy people's commissar of communications A. A. Konyukhov arrived there. We launched work on the installation of nodes and the organization of communications. The Germans bombed Povorino daily. During the bombing, we hid in the nearest ravine, and then continued to work again. But one day, returning from the shelter, we saw the burning fragments of the buildings where we placed our nodes. All the equipment was destroyed as well. There were "claws" and a telephone. We climbed onto the introductory pole with preserved wires. A. A. Konyukhov and I reported to our leaders about what had happened. But by this time the situation had changed and HF communications were deployed in the village of Otradnoye, where the front headquarters soon moved. Soon I was ordered to urgently leave for Stalingrad.

A very difficult situation developed in Stalingrad. All the main lines of communication between Moscow and Stalingrad went along the right bank of the Volga. After the Germans reached its bank above Stalingrad, in the town of Rynok, and below Stalingrad, in the Krasnoarmeysk region, the city was surrounded. On August 23, 1943, the Germans carried out a massive raid. The whole city was on fire. In the most difficult conditions, signalmen of the NK Communications took out all the equipment of the long-distance station to the left bank and installed a backup node in the town of Kapustin Yar, with access to Astrakhan and Saratov. There were no active communication lines left in Stalingrad. The headquarters of the Stalingrad Front was on the right bank. Communication with him could be organized only from the left bank. The HF station of Stalingrad was also moved to the left bank in the town of Krasnaya Sloboda. Together with I. V. Klokov, the responsible representative of the Communications Commission, we gave instructions to draw a line across the Volga.

First of all, we checked whether it is possible to use the existing cable crossing in the Rynok area. It was difficult to drive up to the cable box - the Germans controlled all the approaches. And yet, in a belligerent way, we crawled up to her and checked the serviceability of the cable. It worked, but the Germans answered at the other end. It was impossible to use this cable for our purposes. There was only one way out - to lay a new cable crossing across the Volga. We did not have a river cable. We decided to lay the PTF-7 field cable, which was not suitable for working under water (it got wet after 1-2 days). We called Moscow to urgently send a river cable.

The laying had to be carried out under continuous mortar fire. Oil barges floating along the river caused great harm. Pierced by shells, they floated with the flow, gradually sinking into the water, and cut our cables. Every day I had to put more and more bunches. The HF communications switch was installed in the dugout where the front command was located. LF communication was transmitted to this switch from an HF station located on the left bank.

Finally, the river cable arrived. The drum weighed over a ton. No suitable boat was found. We made a special raft. At night, laying began, but the Germans spotted us and smashed the raft with mortar fire. I had to start all over. Finally the cable was laid. Before freezing, he worked reliably. Later, in addition to it, an overhead line was laid across the ice. The pillars were frozen into ice.

In February, the Germans were defeated. Communication with Stalingrad began to work according to the pre-war scheme.

Great difficulties were encountered in organizing the Government Communications at the Teheran Conference of the Three Allied Powers. In peacetime, the Soviet Union did not have a wired connection with Tehran. It had to be organized. The task was complicated by the fact that Stalin, as the Supreme Commander-in-Chief, needed communication not only with Moscow, but also with all fronts and armies.

I went to Tehran with a group of specialists two months before the meeting to study the situation, make a decision and organize the necessary work on the installation of the HF station and the preparation of communication lines. Having familiarized myself with the situation, I realized that the only line that can solve the problem is the air communication line Ashgabat - Kzyl-Aravat - Astara-Baku, laid along the coast of the Caspian Sea. By agreement with Iran, this line was built by the NK Communications as a bypass for communication with the Transcaucasus, since the Germans broke through to the Caucasus and could cut the lines going to Baku, the Transcaucasian Front, Georgia, and Armenia. It was necessary to find a way out of Tehran to a bypass line. The Iranian communication lines in this direction were in a disgusting state: they went through rice fields and were not available for service. Poles slanted, insulators on many poles were missing, wires hung on hooks or were simply nailed to the poles.

The so-called Indo-European line of communication through Iran has more or less been preserved. It was decided to use it. At one time it was built by the British on metal poles to connect London with India. The line was not used for its intended purpose and was run by Iranian signalmen. It was decided to place the Soviet delegation in the building of the USSR embassy, ​​it was also planned to locate an HF station there. The specified line of communication was brought to the embassy. At the points of Sari and Astara, we made overpasses on our line. Now there were two exits from Tehran to Baku through Astara and to Ashgabat-Tashkent through Kzyl-Aravat (Turkmenistan). Thus, although with great difficulty, it was possible to ensure stable HF communications for the entire duration of the Tehran Conference.

The rapid offensive of our troops in 1943-1945. demanded full tension in the work of the organs and troops of the Government Communications. A characteristic feature of the strategic offensive was the continuous increase in its territory, which gradually covered a strip of up to 2000 km. The depth of attacks on the enemy reached 600-700 km. The headquarters of the fronts were moved up to three times in one operation, and the headquarters of the armies - up to eight. The closest interaction was established between the bodies and troops of the Government Communications and the signalmen of the NK Communications and NK Defense. Joint efforts were carried out reconnaissance of the surviving permanent lines of communication. Issues of joint construction and restoration of lines were carefully coordinated. During the summer-autumn operations of 1943, the Government Communications troops built 4,041 km of new permanent lines, restored 5,612 km of lines, suspended 32,836 km of wires, and built 4,071 km of pole lines. Departments and troops gained experience, they were already capable of solving complex tasks of organizing high-frequency communications in any situation.

If we evaluate the completed tasks, we should dwell on the proposed relocation of the Headquarters of the Supreme High Command from Moscow to other cities. As you know, the Stavka was in Moscow throughout the war, and the Supreme Commander-in-Chief went to the front only once - to the Rzhev region. HF communication with him was maintained by mobile means. However, the decision to move the Headquarters was made twice - in 1941 and 1944. In 1941, when the Germans came close to Moscow and 20-30 km remained to the front line, the leadership of the General Staff turned to Stalin with a proposal to move the Stavka inland. According to the provisions on the conduct of military operations, the Supreme High Command should be located at a distance of 200-300 km from the front line. The situation demanded to determine the point where the Stavka could be moved.

As Marshal I. T. Peresypkin told me, Stalin approached the map and said: "When Ivan the Terrible took Kazan, he had a headquarters in Arzamas, we will stop at this city." With a group of specialists, I went to Arzamas and began to organize the installation of the RF station. For Stalin, a two-story house was chosen, the first floor of which was given to the HF station. During installation, the possibility of going to the fronts was provided, bypassing Moscow. However, only the chief of the General Staff, Marshal B. M. Shaposhnikov, arrived in Arzamas and soon left for Moscow. Instead of Arzamas, they began to prepare premises in Gorky to accommodate the Headquarters and the Government. But he was also rebuffed. The work stopped and we returned to Moscow.

The second time the decision to move the Headquarters was made in 1944, after the successful operation "Bagration" and the liberation of Minsk. Marshal I. T. Peresypkin told me about this and offered to go to Minsk. We left together with K.A. Alexandrov. On the way, discussing the situation in Minsk, we came to the conclusion that it is necessary to strengthen the connection between Minsk and Moscow. Only one circuit operated in this direction, sealed with three-channel equipment. It was decided to hang three more, two of them - by the forces of the NK Communications and NK Defense, and one - by the troops of the Government Communications. Communication centers were deployed in Minsk and a lot of work was done to build bypass lines around the city. After some time, the retreat was again given. The stake remained in Moscow.

Attaching particular importance to the organization of government communications with the fronts and armies, we should not forget about the operation of the entire communications network with the republics, territories and regions, especially since a significant number of new HF stations were opened in the rear - at factories in the defense industries that manufacture weapons for the army, at the places of formation of reserve armies - and a number of others related to the needs of the front. A major role in the successful work of the Government Communications was played by the state of the nationwide network of NC communications. Sometimes additional costs of NC communications were necessary. And I must say that we met with the complete understanding of the leadership of the People's Commissariat of Communications, People's Commissar I. T. Peresypkin, as well as his deputies I. S. Ravich and I. V. Klokov, who closely interacted with us.

On the eve of Victory Day in 1965, the Pravda newspaper wrote: “Special signal troops successfully operated on the fronts of the Patriotic War. prevented attempts by enemy saboteurs to disrupt communications.

Marshal of the Soviet Union I. S. Konev, in his memoirs, spoke of HF communications in the following way: “In general, it must be said that this HF connection, as they say, was sent to us by God. It helped us out so much, was so stable in the most difficult conditions that it was necessary pay tribute to our equipment and our signalmen, who specially provided this HF communication and in any situation literally on the heels of those who were supposed to use this connection during the movement.

The bodies and troops of the Government Communications Service did an excellent job with the tasks assigned to them, making a great contribution to the Victory over Nazi Germany.

For 12 years, who served as deputy chairman of the Interdepartmental Coordinating Council for the creation of the Unified Automated Communications Network of the country, Petr Nikolayevich Voronin during the Great Patriotic War ensured communication between the Headquarters of the Supreme High Command and the headquarters of the fronts and armies. He was engaged in the construction of backup nodes and communication lines in Moscow and around the capital. He took an active part in organizing communications during the days of the defense of Moscow, during the Battle of Stalingrad, lifting the blockade of Leningrad, conducting the Oryol-Kursk, Berlin and other operations. Provided communications to the Supreme Commander-in-Chief during the Tehran and Potsdam Conferences. He was awarded the Order of the October Revolution, Orders of the Patriotic War I and II degrees, three Orders of the Red Banner, three Orders of the Red Banner of Labor, two Orders of the Red Star, other military and labor orders and medals.

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The design of the power line, determined by its main purpose - the transmission of electrical energy over a distance, allows it to be used to transmit information. The high level of operation and high mechanical strength of the lines ensure the reliability of communication channels close to the reliability of channels via cable communication lines. At the same time, when implementing communication channels for information transmission over overhead lines, it is necessary to take into account the features of the lines that make it difficult to use them for communication purposes. Such a feature is, for example, the presence of substation equipment at the ends of the lines, which can be represented as a chain of reactive and active resistances that vary over a wide range and are connected in series. These resistances form a connection between the overhead lines through the buses of substations, which leads to an increase in the communication path. Therefore, to reduce the influence between the channels and attenuation, with the help of special barriers, they block the paths of high-frequency currents towards substations.
Branches from overhead lines also significantly increase attenuation. These and other features of the lines require the implementation of a number of measures to create conditions for the transmission of information.
The device of high-frequency channels along distribution networks of 6-10 kV is associated with significant difficulties due to the specifics of building networks of these voltages. On sections of 6-10 kV trunk lines between neighboring switching points, there are a large number of taps, the lines are sectioned off by disconnectors and switches, the primary switching circuits of networks often change, including automatically, due to the greater damage to the lines of these voltages, their reliability is lower than B71 35 kV and above. Signal transmission in distribution networks depends on many factors that affect signal attenuation: on the length and number of taps, line wire material, load, etc. The load can vary over a wide range. At the same time, turning off individual taps, as studies show, sometimes not only does not reduce attenuation, but, on the contrary, increases it due to a violation of the mutual compensation of attenuation between adjacent taps. Therefore, channels of even a small length have significant attenuation and are unstable. The operation of the channels is also negatively affected by damage to insulators, poor-quality wire connections and the poor condition of the contacts of the switching equipment. These defects are sources of interference commensurate with the level of the transmitted signal, which can cause the channel to stop working and damage the equipment. The presence of sectioning devices on the lines leads to a complete cessation of the operation of the RF channel in the event of their disconnection and grounding of one of the line sections. The noted shortcomings significantly limit, although they do not exclude, the use of 6-10 kV lines for organizing HF channels. Nevertheless, it should be noted that HF ​​communication over distribution networks has not yet received wide distribution.
By purpose, HF communication channels over power lines are divided into four groups: dispatch communication channels, technological, special and linear operational communication channels.
Without dwelling in detail on the use and purpose of each group of channels, we note that for dispatching and technological channels of telephone communication, the voice frequency band of 300-3400 Hz is mainly used.<300-2300). Верхняя часть тонального спектра (2400-3400 Гц) не пользуется для передачи сигналов телеинформации. Современная комбинированная аппаратура позволяет организовать в этом спектре до четырех независимых узкополосных каналов телеииформации.
Line-operational communication channels are used to organize communication between the dispatcher and repair teams working on the route of an extended power line or substations, when there is no permanent connection with them. For these channels, simplified transportable and portable telephone equipment is used.
According to the degree of complexity, HF channels are divided into simple and complex. Channels consisting of only two sets of terminal RF equipment are called simple. Complex channels incorporate intermediate amplifiers or several sets of terminal equipment (at the same frequencies).

Equipment for high-frequency communication channels for overhead lines.

The connection of communication equipment to the wires of the power line is carried out using special devices of the so-called equipment for connecting and processing the line, consisting of a communication capacitor, a barrier and protection elements.

Rice. 21. Scheme of a high-frequency communication channel over overhead lines
On fig. 21 shows a diagram of the formation of a communication channel over an overhead line. Transmission of signals by high-frequency currents It is carried out by transmitters of the sealing equipment J, located at both ends of the overhead lines at substations A and B.
Here, as part of the sealing equipment 1, there are receivers that receive modulated RF currents and convert them. To ensure the transmission of signal energy by high-frequency currents through wires, it is enough to process one wire at each end of the line using a barrier 5, a coupling capacitor 4 and an attachment filter 3, which is connected to sealing equipment 1 using an RF cable 2. To ensure the safety of personnel working on the attachment filter when the RF channel is running, the grounding knife 6 serves.
Connection of high-frequency equipment according to the scheme of fig. 21 is called phase-to-earth. Such a scheme can be used to form single-channel and multi-channel information transmission systems. Other connection schemes are also used.
If it is necessary to connect equipment installed on the line route to the power line (mobile telephone equipment of repair teams, equipment of a remotely controlled VHF radio station, etc.), antenna connection devices are usually used. As an antenna, pieces of insulated wire of a certain length or sections of a lightning protection cable are used.
The high-frequency (linear) arrester has a high resistance to the operating frequency of the channel and serves to block the path of these currents, reducing their leakage towards the substation. In the absence of a barrier, the attenuation of the channel may increase, since the small input impedance of the substation shunts the RF channel. The barrier consists of a power coil (reactor), a setting element and a protection device. The power coil is the main element of the minelayer. It must withstand the maximum operating currents of the line and short-circuit currents. The power coil is made of copper or aluminum wires of the appropriate section, twisted into a spiral, wound on laths of wood-laminated plastic (delta-wood) or fiberglass. The ends of the rails are fixed on metal crosses. An adjustment element with protective arresters is attached to the upper crosspiece. The tuning element serves to obtain a relatively high barrier resistance at one or more frequencies or frequency bands.
The tuning element consists of capacitors, inductors and resistors and is connected in parallel
power coil. The power coil and the setting element of the barrier are exposed to atmospheric and switching overvoltages and short circuits. The role of overvoltage protection, as a rule, is performed by a valve-type arrester, consisting of a spark gap and a non-linear wilite resistor.
In electrical networks of 6-220 kV, barriers VZ-600-0.25 and KZ-500, as well as barriers with a steel core of types VChZS-100 and VChZS-100V, which differ from each other in rated current and inductance, stability and geometric parameters power coil, as well as the type of setting element and its protection.
The barriers cut into the phase wire of the power line between the line disconnector and the coupling capacitor. High-frequency barriers can be mounted suspended, on supporting structures, including coupling capacitors.
Coupling capacitors are used to connect the RF equipment to the overhead line, while the leakage currents of industrial frequency are diverted through the coupling capacitor to the ground, bypassing the high frequency equipment. Coupling capacitors are designed for phase voltage (in a network with grounded neutral) and for line voltage (in a network with isolated neutral). In our country, two types of coupling capacitors are produced: CMP (coupling, oil-filled, with an expander) and CMM (coupling, oil-filled, in a metal case). For different voltages, capacitors are made up of individual elements connected in series. Coupling capacitors can be installed on reinforced concrete or metal supports with a height of about 3 m. To isolate the lower element of the CMP type capacitor from the body of the support, special round-section porcelain supports are used.

The connection filter serves as a link between the coupling capacitor and the RF equipment, separating the high voltage line from the low current installation, which is the sealing equipment. The connection filter thus ensures the safety of personnel and protection of equipment from high voltage, since when the lower lining of the coupling capacitor is grounded, a path is formed for leakage currents of industrial frequency. With the help of the connection filter, the wave impedances of the line and the high-frequency cable are matched, as well as the reactance of the coupling capacitor is compensated in a given frequency band. Connection filters are made according to transformer and autotransformer circuits and together with coupling capacitors form band-pass filters.
The most widely used in the organization of HF communication channels along the power lines of the enterprise was the connection filter of the OFP-4 type (see Fig. 19). The filter is enclosed in a welded steel housing with a bushing for connecting the coupling capacitor and a cable funnel for entering the RF cable. An arrester is mounted on the housing wall, which has an elongated pin for connecting the ground bar and is designed to protect the connection filter elements from overvoltages. The filter is designed for connection of HF equipment in a phase-to-ground circuit, complete with coupling capacitors with a capacity of 1100 and 2200 pF. The filter is installed, as a rule, on the support of the coupling capacitor and is bolted to the support at a height of 1.6-1.8 m from the ground level.
As noted, all switching in the connection filter circuits is carried out with the grounding knife turned on, which serves to ground the lower lining of the coupling capacitor during personnel work. A single-pole disconnector for a voltage of 6-10 kV is used as a grounding knife. Operations with a grounding knife are carried out using an insulating rod. Some types of connection filters have a grounding knife mounted inside the housing. To ensure safety in this case, a free-standing earthing knife should be installed.
The high-frequency cable is used for the electrical connection of the connection filter (see Fig. 21) with the transceiver equipment. When connecting the equipment to the line according to the phase-to-ground scheme, coaxial cables are used. The most common is a high-frequency coaxial cable of the brand RK-75, the inner conductor (solid or stranded) of which is separated from the outer braid by insulation from a high-frequency dielectric. The outer shield braid serves as the return conductor. The outer conductor is enclosed in a protective insulating sheath.
The high-frequency characteristics of the RK-75 cable, as well as conventional communication cables, are determined by the same parameters: wave resistance, kilometer attenuation and electromagnetic wave propagation speed.
Reliable operation of HF channels over overhead lines is ensured by high-quality and regular execution of scheduled preventive maintenance, which provides for a whole range of work on the equipment of HF communication channels over overhead lines. To perform preventive measurements, the channels are taken out of service. Preventive maintenance includes scheduled checks of equipment and channels, the frequency of which is determined by the condition of the equipment, the quality of operational maintenance, taking into account preventive maintenance, and is set at least once every 3 years. Unscheduled channel checks are performed when the RF path is changed, equipment is damaged, and the channel is unreliable due to violation of the regulated parameters.

The third

Second

First

Transformer protection circuit, in which there is a differential and gas protection (DZ) that react to the transformer trip on both sides and maximum current protection (CZ), which should cut off only on one side.

When drawing up a circuit diagram of relay protection in a collapsed form, the electrical connection of the trip circuits of two switches may not be detected. From the expanded scheme (Scheme 1) it follows that with such a connection (transverse chain), a false chain is inevitable. Two operational contacts are required for safety relays (Diagram 2) acting on two circuit breakers or an isolating intermediate relay (Diagram 3).

Rice. – Transformer protection scheme: 1 – incorrect; 2.3 - correct

Undivided high and low voltage circuits transformer.

Figure (1) shows the impossibility of independently disconnecting one of the sides of the transformer without disconnecting the other.

This situation is corrected by switching on the intermediate relay KL.

Rice. – Transformer protection schemes: 1 – incorrect; 2 - correct

The protection of the generator and transformer of the unit at the power plant act, as required, to turn off the circuit breaker and the field extinguisher through the separating intermediate relays KL1 and KL2, but the relays are connected to different sections of the power buses, i.e. through different fuses.

The false circuit shown by the arrows was formed through the fuse control lamp HL as a result of the blown fuse FU2.

Rice. – Formation of a false circuit when a fuse blows

1, 2, 3 - operational relay contacts

Schemes with supply of circuits of secondary connections with operational direct and alternating current

With the power supply poles well insulated from earth, a ground fault at any one point in the secondary connection chain usually does not entail harmful consequences. However, a second ground fault can cause false switching on or off, incorrect alarms, etc. Preventive measures in this case can be:

a) signaling of the first earth fault in one of the poles; b) two-pole (two-way) separation of control circuit elements - practically not used due to complexity.

With isolated poles (Fig.) grounding at a point but with open NO contacts 1 will not yet cause a false action of the coil of the command organ K, but as soon as a second insulation fault appears on the ground in the branched network of the positive pole, a false operation of the apparatus is inevitable, since the contact 1 turns out to be shunted. That is why ground fault signaling is necessary in operational circuits, and above all at the poles of the power source.

Rice. – False operation of the device at the second earth fault

However, in complex circuits with a large number of operational contacts connected in series, such an alarm may not detect a ground fault (Fig.).

Rice. – Inefficiency of insulation control in complex circuits

When grounding appears between the contacts at the point but signaling is not possible.

In the practice of operating automatic installations with low-current equipment (up to 60 V), they sometimes resort to intentional grounding of one of the poles, for example, the positive one (it is more dusty and prone to electrolytic phenomena, i.e. it already has weakened insulation). This facilitates the detection and elimination of an emergency source. In this case, it is recommended to connect the control circuit coil at one end to the earthed pole.

Everything that has been said about the supply of circuits at a direct operating current can also be attributed to the operational alternating current with the supply of circuits by linear voltage. In this case, the probability of false operation (due to capacitive currents) and resonance phenomena should be taken into account. Since it is difficult to foresee the conditions for reliable operation in this case, auxiliary isolating intermediate transformers are sometimes used with grounding of one of the terminals on the secondary side.

As can be seen from the diagram, in this case, if the insulation to the ground at point 2 is damaged, the fuse FU1 blows and a ground fault at point 1 does not cause false switching on of the contactor K.

Scheme for switching capacitors with isolation diodes

High-frequency (HF) communication over high-voltage lines has become widespread in all countries. In Ukraine, this type of communication is widely used in power systems to transmit information of various kinds. High-frequency channels are used to transmit signals of relay protection of lines, remote shutdown of switches, telesignaling, telecontrol, telecontrol and telemetering, for dispatching and administrative telephone communications, as well as for data transmission.

Communication channels over power lines are cheaper and more reliable than channels over special wired lines, since no funds are spent on the construction and operation of the actual communication line, and the reliability of the power line is much higher than the reliability of conventional wired lines. The implementation of high-frequency communication over power lines is associated with features that are not found in wired communication.

To connect communication equipment to the wires of power lines, special processing and connection devices are required to separate high voltage from low-current equipment and implement a path for transmitting HF signals (Fig. 1).

Rice. – Connection of high-frequency communication equipment to high voltage lines

One of the main elements of the scheme for connecting communication equipment to power lines is a high voltage coupling capacitor. The coupling capacitor, switched on to the full voltage of the network, must have sufficient dielectric strength. To better match the input resistance of the line and the connection device, the capacitance of the capacitor must be large enough. Coupling capacitors produced now make it possible to have a connection capacitance on lines of any voltage class of at least 3000 pF, which makes it possible to obtain connection devices with satisfactory parameters. The coupling capacitor is connected to the connection filter, which grounds the lower plate of this capacitor for power frequency currents. For high-frequency currents, the connection filter, together with the coupling capacitor, matches the resistance of the high-frequency cable with the input impedance of the power line and forms a filter for transferring high-frequency currents from the high-frequency cable to the line with low losses. In most cases, a coupling filter with a coupling capacitor forms a band-pass filter circuit that passes a certain frequency band.

The high-frequency current, passing through the coupling capacitor along the primary winding of the ground connection filter, induces a voltage in the secondary winding L2, which, through the capacitor C1 and the connecting line, enters the input of the communication equipment. The power frequency current passing through the coupling capacitor is small (from tens to hundreds of milliamps), and the voltage drop across the coupling filter winding does not exceed a few volts. In the event of an open or poor contact in the connection filter circuit, it may be under full line voltage, and therefore, for safety reasons, all work on the filter is carried out when the lower capacitor plate is grounded with a special grounding knife.

By matching the input impedance of the RF communication equipment and the line, the minimum energy loss of the RF signal is achieved. Coordination with an overhead line (VL) having a resistance of 300–450 Ohm is not always possible to complete completely, since with a limited capacitance of the coupling capacitor, a filter with a characteristic resistance from the side of the line equal to the characteristic resistance of the VL may have a narrow bandwidth. In order to obtain the required bandwidth, in some cases it is necessary to allow an increased (up to 2 times) characteristic resistance of the filter on the line side, putting up with slightly larger losses due to reflection. The connection filter, installed at the coupling capacitor, is connected to the equipment with a high-frequency cable. Several high-frequency devices can be connected to one cable. Separating filters are used to reduce mutual influences between them.

System automation channels - relay protection and teleshutdown, which must be especially reliable, require the mandatory use of separation filters to separate other communication channels operating through a common connection device.

To separate the HF signal transmission path from the high voltage equipment of the substation, which may have low resistance for high frequencies of the communication channel, a high-frequency arrester is included in the phase wire of the high voltage line. The high-frequency barrier consists of a power coil (reactor), through which the operating current of the line passes, and a tuning element connected in parallel with the coil. The power coil of the barrier with the tuning element form a two-terminal circuit, which has a sufficiently high resistance at operating frequencies. For an industrial frequency current of 50 Hz, the barrier has a very low resistance. Barriers are used that are designed to block one or two narrow bands (one- and two-frequency barriers) and one wide frequency band of tens and hundreds of kilohertz (broadband barriers). The latter are most widely used, despite the lower resistance in the stopband compared to single- and dual-frequency ones. These barriers make it possible to block the frequencies of several communication channels connected to the same line wire. The high resistance of the barrier in a wide frequency band can be provided the easier, the greater the inductance of the reactor. It is difficult to obtain a reactor with an inductance of several millihenries, since this leads to a significant increase in the size, weight, and cost of the minelayer. If we limit the active resistance in the band of blocked frequencies to 500–800 Ohm, which is sufficient for most channels, then the inductance of the power coil can be no more than 2 mH.

The barriers are produced with inductance from 0.25 to 1.2 mH for operating currents from 100 to 2000 A. The operational current of the barrier is the higher, the higher the line voltage. For distribution networks, barriers are produced for 100–300 A, and for lines of 330 kV and above, the maximum operating current of the barrier is 2000 A.

Various tuning circuits and the required range of blocked frequencies are obtained using capacitors, additional inductors and resistors available in the minelayer tuning element.

Connection to the line can be done in various ways. With an asymmetric RF circuit, the equipment is connected between a wire (or several wires) and ground according to the "phase - ground" or "two phases - ground" schemes. With symmetrical RF circuits, the equipment is connected between two or more line wires (“phase - phase”, “phase - two phases”). In practice, the phase-to-phase scheme is used. When the equipment is turned on between the wires of different lines, only the "phase - phase of different lines" scheme is used.

To organize HF channels along high voltage lines, a frequency range of 18–600 kHz is used. Distribution networks use frequencies ranging from 18 kHz, on trunk lines 40–600 kHz. To obtain satisfactory parameters of the RF path at low frequencies, large values ​​of the inductances of the power coils of the barriers and capacitances of the coupling capacitors are required. Therefore, the lower frequency limit is limited by the parameters of the processing and connection devices. The upper limit of the frequency range is determined by the allowable value of linear attenuation, which increases with increasing frequency.

1. HIGH FREQUENCY LOADERS

Schemes for setting minelayers. High-frequency barriers have a high resistance to the currents of the operating frequency of the channel and serve to separate the elements shunting the RF path (substations and branches), which, in the absence of barriers, can lead to an increase in the attenuation of the path.

The high-frequency properties of the barrier are characterized by the stop band, i.e., the frequency band in which the resistance of the barrier is not less than a certain acceptable value (usually 500 ohms). As a rule, the barrier strip is determined by the permissible value of the active component of the barrier resistance, but sometimes by the permissible value of the impedance.

The barriers differ in inductance values, permissible currents of power coils and in tuning schemes. One- and two-frequency resonant or blunt tuning circuits and broadband circuits are used (according to the circuit of a full link and a half-link of a band-pass filter, as well as according to a half-link circuit of a high-pass filter). Jammers with single- and dual-frequency tuning schemes often do not make it possible to block the desired frequency band. In these cases, barriers with broadband tuning schemes are used. Such configuration schemes are used when organizing protection and communication channels that have common connection equipment.

When current flows through the barrier coil, electrodynamic forces arise, acting along the axis of the coil, and radial, tending to break the coil. Axial forces are uneven along the length of the coil. Large forces occur at the edges of the coil. Therefore, the pitch of the turns on the edge is done more.

The electrodynamic resistance of the barrier is determined by the maximum short-circuit current that it can withstand. In the KZ-500 barrier, at a current of 35 kA, axial forces of 7 tons (70 kN) occur.

Overvoltage protection of tuning elements. An overvoltage wave that occurs on an overhead line hits the barrier. The wave voltage is distributed between the capacitors of the tuning element and the input impedance of the substation busbars. The power coil is a large resistance to a wave with a steep front and when considering the processes associated with overvoltages, it can be ignored. To protect the tuning capacitors and the power coil, a spark gap is connected in parallel with the power coil, which limits the voltage on the elements of the barrier to a safe value for them. The breakdown voltage of the arrester, according to the conditions of deionization of the spark gap, should be 2 times greater than the accompanying voltage, i.e., the voltage drop across the power coil from the maximum short current U resist = I short. ωL.

With a large pre-discharge time, the breakdown voltage of the capacitors is much greater than the breakdown voltage of the arresters; at low (less than 0.1 μs) the breakdown voltage of the capacitors becomes less than the breakdown voltage of the arrester. Therefore, it is necessary to delay the growth of voltage on the capacitors until the arrester is triggered, which is achieved by turning on an additional inductance coil Ld in series with the capacitor (Fig. 15). After the breakdown of the arrester, the voltage across the capacitor rises slowly and an additional arrester, connected in parallel with the capacitor, protects it well.

Rice. - Schemes of high-frequency barriers with a surge protection device: a) single-frequency; b) dual frequency

2. COUPLING CAPACITORS

General information. Coupling capacitors are used to connect HF communication equipment, telemechanics and protection to high voltage lines, as well as for power take-off and voltage measurement.

The resistance of a capacitor is inversely proportional to the frequency of the voltage applied to it and the capacitance of the capacitor. The reactance of the coupling capacitor for industrial frequency currents, therefore, is significantly greater than for the frequency of 50 - 600 kHz telemechanics and protection communication channels (1000 times or more), which allows using these capacitors to separate high and industrial frequency currents and prevent high voltage in electrical installations. Industrial frequency currents are diverted to the ground through coupling capacitors, bypassing the RF equipment. Coupling capacitors are designed for phase (in a network with a grounded neutral) and for linear voltage (in a network with an isolated neutral).

For power take-off, special take-off capacitors are used, connected in series with the coupling capacitor.

In the names of the elements of capacitors, the letters designate in sequence the nature of the application, the type of filler, the execution; figures - rated phase voltage and capacitance. CMP - connections, oil-filled, with an expander; SMM - connections, oil-filled, in a metal casing. For different voltages, coupling capacitors are made up of individual elements connected in series. Capacitor elements CMP-55 / √3-0.0044 are designed for normal operation at a voltage of 1.1 U iohm, elements CMP-133 / √3-0.0186 - for 1.2 U iohm. The capacitance of capacitors for insulation classes 110, 154, 220, 440 and 500 kV is accepted with a tolerance of -5 to +10%.

3. CONNECTION FILTERS

General information and calculated dependencies. High-frequency equipment is connected to the capacitor not directly through the cable, but through the connection filter, which compensates for the reactance of the capacitor, matches the wave impedances of the line and the RF cable, grounds the lower lining of the capacitor, which forms a path for industrial frequency currents and ensures safety.

When the circuit of the linear winding of the filter is broken, a phase voltage appears on the lower plate of the capacitor with respect to the ground. Therefore, all switching in the linear winding circuit of the connection filter is carried out with the grounding knife turned on.

The OFP-4 filter (Fig. ,) is designed to operate on 35, 110 and 220 kV lines according to the “phase-to-ground” scheme with a coupling capacitor of 1100 and 2200 pF and with a cable with a wave impedance of 100 Ohm. The filter has three frequency bands. For each range there is a separate air transformer filled with insulating mass.

Rice. – Principal diagram of filter-connection OFP-4

6. PROCESSING OF LIGHTNING PROTECTION CABLES, ANTENNA

Lightning wires of high voltage lines can also be used as information transmission channels. The cables are isolated from the supports in order to save electricity; in case of atmospheric overvoltages, they are grounded through punched spark gaps. Steel cables have high attenuation for high-frequency signals and allow information to be transmitted only on short lines at frequencies not exceeding 100 kHz. Bimetallic cables (aluminum-coated steel cables), aluminum-weld cables (made of twisted steel-aluminum wires), single-strand cables (one strand is aluminum wires, the other strands are steel) make it possible to organize communication channels with low attenuation and noise levels. Interference is less than in communication channels via phase wires, and RF processing and connection equipment is simpler and cheaper, since the currents flowing through the cables and the voltages on them are small. Bimetallic wires are more expensive than steel wires, so their use can be justified if RF channels through phase wires cannot be made. This can be on ultra-long, and sometimes on long-distance power lines.

Cable channels can be switched on according to the schemes "cable - cable", "cable - earth" and "two cables - earth". On AC overhead lines, the cables are interchanged every 30 - 50 km to reduce the interference of industrial frequency currents in them, which introduces an additional attenuation of 0.15 Np for each crossing in the “cable - cable” schemes, without affecting the “two cables - Earth". On DC transmissions, the “cable-cable” scheme can be used, since crossing is not necessary here.

Communication over lightning protection cables is not interrupted when the phase conductors are grounded, and does not depend on the line switching scheme.

Antenna communication is used for mobile RF equipment connected to the overhead line. The wire is suspended along the wires of the overhead line or a section of a lightning protection cable is used. Such an economical method of connection does not require barriers and coupling capacitors.

The division of the vertically integrated structure of the post-Soviet power industry, the complication of the control system, the increase in the share of small-scale electricity generation, new rules for connecting consumers (reducing the time and cost of connection), while increasing requirements for the reliability of power supply entails a priority attitude to the development of telecommunications systems.

In the energy sector, many types of communication are used (about 20) differing in:

• appointment,
• transmission medium,
• physical principles of work,
• type of transmitted data,
• transmission technologies.

Among all this diversity, HF communications along high-voltage lines (HVL) of power transmission stand out, which, unlike other types, was created by power engineers for the needs of the electric power industry itself. Other types of communication equipment, originally designed for public communication systems, to one degree or another, is being adapted to the needs of energy companies.

The very idea of ​​using overhead lines for the dissemination of information signals arose during the design and construction of the first high-voltage lines (since the construction of a parallel infrastructure for communication systems entailed a significant rise in cost), respectively, already in the early 20s of the last century, the first commercial HF communication systems were put into operation.

The first generation of HF communications was more like radio communications. The connection of the transmitter and receiver of high-frequency signals was carried out using an antenna up to 100 m long, suspended on supports parallel to the power wire. The overhead line itself was the guide for the HF signal - at that time, for speech transmission. Antenna connection was used for a long time to organize the communication of emergency teams and in railway transport.

Further evolution of HF communication led to the creation of HF connection equipment:

• coupling capacitors and coupling filters, which made it possible to expand the band of transmitted and received frequencies,
• HF trappers (barrier filters), which made it possible to reduce the influence of substation devices and overhead line inhomogeneities on the characteristics of the HF signal to an acceptable level, and, accordingly, improve the parameters of the HF path.

The next generations of channel-forming equipment began to transmit not only speech, but also telecontrol signals, protective commands of relay protection, emergency automation, and made it possible to organize data transmission.

As a separate type of HF communication was formed in the 40s, 50s of the last century. International Standards (IEC), guidelines for the design, development and manufacture of equipment have been developed. In the 70s in the USSR, by the efforts of such specialists as Shkarin Yu.P., Skitaltsev V.S. Mathematical methods and recommendations for calculating the parameters of HF paths were developed, which greatly simplified the work of design organizations in designing HF channels and selecting frequencies, and increased the technical characteristics of the introduced HF channels.

Until 2014, HF communication was officially the main type of communication in the electric power industry in the Russian Federation.

The emergence and introduction of fiber-optic communication channels, in the context of the widespread use of high-frequency communications, has become a complementary factor in the modern concept of the development of communication networks in the electric power industry. Currently, the relevance of HF communications remains at the same level, and intensive development and significant investments in the optical infrastructure contribute to the development and formation of new areas of application of HF communications.

The undeniable advantages and the presence of huge positive experience in the use of HF communications (almost 100 years) give reason to believe that the direction of HF will be relevant both in the short and long term, the development of this type of communication will solve both current problems and contribute to the development of the entire electric power industry. industries.

Communication channel - a set 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 information is stored).

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 over it are subjected. There are linear and non-linear distortions. Linear distortions consist of frequency and phase distortions and are described by the transient response or, equivalently, the complex channel gain. Non-linear distortions are given by non-linear dependencies, indicating how the signal changes when passing through the communication channel.

A communication channel is characterized by a set 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 the 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 modes of operation of transmitters, in telegraphy, telemetry, and radar.

Several different channels may use the same technical link. In these cases (for example, in multichannel communication lines with frequency or time division of 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)- this 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 the power grids. 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 substation switchgear busbars, and the communication signals to the corresponding communication sets, high-frequency barriers and communication capacitors are used.

The RF barrier has a small resistance at the industrial frequency current and a large resistance at the frequency of the high-frequency communication channels. Link Capacitor- on the contrary: it has a large resistance at a frequency of 50 Hz, and at the frequency of the communication channel - a small resistance. Thus, it is ensured that only 50 Hz current reaches the substation buses, and only signals at a high frequency reach 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 equipment sets are installed that perform certain functions. Below we consider which functions can be implemented using RF communication.

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

The channel for transmitting signals of relay protection of power lines (TL) is called relay protection channel. Three types of HF protections 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 through the HF channel in case of an external short circuit; in differential-phase protection, HF voltage pulses are transmitted through the relay protection channel. The duration of pulses and pauses is approximately the same and equal to half the period of the industrial frequency. With an external short circuit, the transmitters located at both ends of the line operate in different half-cycles of the industrial frequency. Each of the receivers receives the signals from both transmitters. As a consequence, 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, the phases of the manipulating voltages are shifted 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 that acts to turn off the circuit 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 lines, relay protection channels are sometimes performed 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. Relay protection channels use a special (dedicated) RF channel.

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

Another function is telephony function. The RF 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 maintenance personnel of the facilities, but the HF channel can serve as a backup communication channel in case of an emergency when there is no mobile or wired telephone connection.

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 circuit (Fig. 1), which is most common due to its efficiency, the following circuits are used: phase - phase, phase - two phases, two phases - earth, three phases - earth, phase - phase of different lines. The HF trap, coupling capacitor and connection filter used in these schemes are power transmission line processing equipment for organizing HF communication channels along their wires.

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

Line processing is needed to obtain a stable communication channel. The attenuation of the HF channel over the processed power lines is almost independent of the line switching scheme. In the absence of processing, communication will be interrupted when the ends of the power line are disconnected or grounded. One of the most important problems of communication over power lines is the lack of frequencies due to the low crosstalk between lines connected via substation buses..

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

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

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

specialized equipment for any one of the listed functions;

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

line impulse control equipment.