Overhead high-voltage power lines. Power lines, their characteristics and classification

One fine day in May I had the opportunity to visit one of the most ambitious power line crossings in the world. We are talking about crossings of high-voltage lines 330 kV and 750 kV through the Kakhovskoe reservoir in Ukraine.

Having arrived at the place, I first removed the intermediate supports in the fields behind Ilyinka. This was a kind of “warping up” before a photo shoot of the giant transition supports that beckoned me from the side of the reservoir)

First of all, I removed the supports of two single-circuit 330 kV power lines. The supports were U-shaped reinforced concrete, with internal bracing - PVA. In the photo, these supports are captured against the background of a yellow field with rapeseed.

Parallel to the 330 kV line, a 750 kV power line ran past Ilyinka. I especially liked the very elegant looking 750kV intermediate support.

If the intermediate support of a 750 kV transmission line looks quite elegant, like a giraffe, then the anchor supports of this line, in comparison, are wide and tightly built. It was near this support that I began to “listen” to the line. Everyone knows that power lines hum or crackle, and usually the higher the voltage class, the louder the noise. I remembered that the 750 kV power lines were humming loudly, but to my surprise I discovered dead silence under the line - absolutely nothing, the power line was clearly not working! And the 330 kV power lines nearby were cracking quite loudly.

Then, I forced the anchor support of a 750 kV power line to “hold” the sun on its wires)))

Now I had to relocate to the transition supports that were visible on the horizon; on the way to them I removed several 330 kV and 750 kV supports.

It was here that I first met “glass” type supports on the 330 kV line; they were similar in type to the glass glasses of the 500 kV lines.

To be honest, few types of props have evoked such emotions in me as this one. The crackling sound beneath her was unimaginable. The wires seemed to trail along the ground. The massiveness of this monster was amazing!

The 330kV end tower was the forerunner of the “sea” crossing. I finally took my first shot of the transition supports.

And now about the history of creating transitions. In the 70s of the last century, in the south of the Zaporozhye region, on the left bank of the Kakhovka reservoir, the Zaporozhye State District Power Plant with a capacity of 3 million 600 thousand kW was built. Economically, it was necessary to build two power transmission lines with a voltage of 330 kV to the Nikopol energy district, located on the right bank of the reservoir. The crossing of lines through water spaces of such a length had not previously been constructed in the Soviet Union.

For the first crossing being constructed (330 kV), the designers chose the overhead version of the line (the cable underwater version was unprofitable and difficult to construct and operate). The length of the transition between the outer transition supports was as much as 5.15 km (!), and directly above the water - 4.6 km. The transition was made in two circuits.

Coastal transition support for power lines 330 kV

At the 330 kV crossing, seven anchor-type transition supports with a height of 90 and 100 meters were installed, of which five were installed in the water area of ​​the reservoir. Transition accepted by scheme K-A-A-A-A-A-A-A-K(K - end support, A - anchor). The span lengths of 330 kV power lines are 810 - 920 m. Double-circuit tower-type supports are made of galvanized angle steel.

The supports are equipped with stairs, platforms and fenced ladders on traverses, and you can easily climb the support - the stairs descend directly to the ground, unlike most other passages, where ladders usually do not reach the ground 2-3 meters, in order to reduce the temptation of “tourists” climb the mast. IN in this case Apparently, the sparsely populated area played a role.

The mass of a hundred-meter support is 290 tons, and a ninety-meter one is 260 tons. Externally, both types of supports are very similar; you can notice the differences only by carefully examining them.

The greatest difficulty was the construction of the foundations of these supports on the territory of the reservoir. Installation of transition supports in the water area is a very difficult task, requiring special arrangement of the foundation site with temporary berths and lifting mechanisms. Therefore, for the first time in the practice of power transmission line construction (both in our country and abroad), a decision was made to construct a crossing using the floating method. Therefore, in a special pit - a dock, floating foundations were built and transition supports were mounted on them. The floating foundations were made hollow, from thin-walled reinforced concrete elements and, in fact, were huge floats.

To ensure their buoyancy, the foundation was assembled from a watertight bottom, outer side and internal bulkheads, dividing the interior of the foundation into 8 ballast compartments isolated from each other, as well as a compartment for placing equipment and a central distribution compartment. This design ensured the unsinkability of the foundation and the accuracy of its ballasting, as well as the necessary stability during the period of towing by ships.

After completion of construction work on the foundations and installation of transition supports on them, the pit was filled with water up to the level of the Kakhovka reservoir. When the seawalls were open, the internal compartments of the foundations were simultaneously filled with water. After this, the lintel separating the dock pit and the Kakhovskoe reservoir was dismantled (the process is in the photo).

One by one, with the kingstones closed, water was pumped out from each foundation with powerful pumps, and after it floated to the surface, it was towed to the installation site on the transition route. Towing of supports across the reservoir and work on their installation were carried out using five towing motor ships - two head ships (with a power of 1200 hp each); two side (300 hp each) and one rear (brake) 600 hp. Delivery of all five foundation-support systems was completed within 12 days. After delivering the foundations to their destination, the compartments were flooded again, as a result of which the foundations settled in the required place at the bottom of the reservoir.

The 330 kV transmission line crossing (L243/244) was put into operation in 1977. In 1984, to supply power to the Zaporozhye NPP, the same composition of construction and installation organizations, using a similar floating method, built a single-circuit transition of the 750 kV line “Zaporozhye NPP - 750 kV Dneprovskaya substation” (powerful electrical substation near Volnogorsk, see http://io.ua /s75116).

Supports in the dock

The crossing point for the more powerful 750 kV line was chosen in the area where the Zaporozhye State District Power Plant is located, parallel to the existing crossing of the 330 kV overhead line, at a distance of 350 m upstream. When making the decision to build a 750 kV overhead line crossing across the Kakhovskoye Reservoir - a unique structure in terms of its scale and line power - the experience of designing and constructing a 330 kV line crossing played a major role. The transition was made single-chain by pattern K-P-P-A-P-P-K; of five transition supports, of which three supports are installed in the water area of ​​the reservoir. The crossing supports for this line are also galvanized.

The transitional intermediate supports, 126 m high, weigh 375 tons each. An anchor support 100 m high weighs 350 tons. The lengths of the transition spans are 1215-1350 meters. The installation of the wires was carried out using unrolling barges and tugs without lowering them to the bottom of the reservoir to avoid damage. The transition of the 750 kV line was put into operation in 1984.

750 kV transitional shore support.

Top of the tower 750kV

750kV tower foundation

Ladder for transitional support of 750 kV power line

Giant coastal transition support No. 26 750 kV power line

For an experienced electrician who has been working with overhead power lines for many years, it will not be difficult to visually determine the voltage of an overhead line by the type of insulators, supports, and the number of wires in the line without any instruments. Although in most cases, to determine the voltage on an overhead line, you just need to look at the insulators. After reading this article, you will also be able to easily determine the voltage of overhead lines using insulators.

Photo 1. Pin insulators for voltage 0.4, 6-10, 35 kV.

Every person should know this! But why, why does a person far from the electric power industry need to be able to determine the voltage of an overhead power line by the appearance of the insulators and the number of insulators in the overhead power line garland? The answer is obvious, it's all about electrical safety. After all, for each voltage class of overhead lines, there are minimum permissible distances, closer than which approaching the overhead line wires is deadly.

In my practice, there were several accidents associated with the inability to determine the voltage class of overhead lines. Therefore, below is a table from the safety rules, which indicates the minimum permissible distances, the closer of which it is deadly to approach live parts that are energized.

Table 1. Permissible distances to live parts that are energized.

*D.C.

Case one occurred at the construction site of a country house. By unknown reason There was no electricity at the construction site; a 10 kV overhead line ran near the unfinished house. Two workers decided to power an extension cord from this overhead line to connect power tools. After stripping two wires on the extension cord and making hooks, they decided to use a stick to hook them to the wires. On a 0.4 kV overhead line, this scheme would work. But since the voltage of the overhead line was 10 kV, one worker received serious electrical injuries, and miraculously survived.

Second case occurred on the territory of the production base while unloading pipes. A working slinger was unloading metal pipes from a truck using a truck crane in the coverage area of ​​a 110 kV overhead line. During unloading, the pipes bent so that one end came dangerously close to the wires. And even despite the fact that there was no direct contact of the wires with the load, due to high voltage a breakdown occurred and the worker died. After all, you can be killed by electric shock from a 110 kV overhead line even without touching the wires, you just need to get close to them. I think it’s now clear why it is so important to be able to determine the voltage of overhead lines by the type of insulators.

The main principle here is that the higher the power line voltage, the more insulators will be in a garland. By the way, the highest voltage power line in the world is located in Russia, its voltage is 1150 kV.

The first type of line whose voltage you need to know in person is a 0.4 kV overhead line. These overhead line insulators are the smallest, usually pin insulators made of porcelain or glass, mounted on steel hooks. The number of wires in such a line can be either two, if it is 220V, or 4 or more, if it is 380V.

Photo 2. Wooden support of 0.4 kV overhead line.

The second type is VL-6 and 10 kV; outwardly they do not differ. 6 kV overhead lines are gradually becoming a thing of the past, giving way to 10 kV overhead lines. The insulators of these lines are usually pin-type, but are noticeably larger than 0.4 kV insulators. Suspension insulators, one or two in a garland, can be used on corner supports. They are also made of glass or porcelain, and are mounted on steel hooks. So: the main thing visual difference VL-0.4 kV from VL-6, 10 kV, these are larger insulators, as well as only three wires in the line.

Photo 3. Wooden support of 10 kV overhead line.

The third type is 35kV overhead line. Suspended insulators, or pin insulators, are already used here, but much larger size. The number of pendant insulators in a garland can be from three to five, depending on the support and type of insulators. The supports can be either concrete or made of metal structures, as well as wood, but then it will also be a structure, and not just a pole.

Photo 4. Wooden support of 35 kV overhead line.

110 kV overhead line from 6 insulators in a garland. Each phase, single wire. The supports can be reinforced concrete, wooden (almost never used) or assembled from metal structures.

Photo 5. Reinforced concrete support of 110 kV overhead line.

220 kV overhead line from 10 insulators in a garland. Each phase is carried out with a thick single wire. With voltages above 220 kV, supports are assembled from metal structures or reinforced concrete.

Photo 6. 220 kV power line support.

330 kV overhead line from 14 insulators in a garland. There are two wires in each phase. The security zone of these overhead power lines is 30 meters on both sides of the outermost wires.

Photo 7. 330 kV transmission line support.

500 kV overhead line from 20 insulators in a garland, each phase is carried out with a triple wire arranged in a triangle. Security zone 40 meters.

Photo 8. 500 kV transmission line support.

750 kV overhead line from 20 insulators in a garland. Each phase has 4 or 5 wires arranged in a square or ring. Security zone 55 meters.

Photo 9. 750 kV transmission line support.

Table 2. Number of insulators in an overhead line garland.

What do the inscriptions on overhead line supports mean?

Surely many have seen the inscriptions on power transmission poles in the form of letters and numbers, but not everyone knows what they mean.

Photo 10. Designations on power line supports.

They mean the following: capital letter the voltage class is indicated, for example T-35 kV, S-110 kV, D-220 kV. The number after the letter indicates the line number, the second number indicates the serial number of the support.

• T means 35 kV.
• 45 is the line number.
• 105 is the serial number of the support.

This method of determining power line voltage by the number of insulators in a garland is not accurate and does not provide a 100% guarantee. Russia is a huge country, so for different conditions operation of power lines (cleanliness of the surrounding air, humidity, etc.) the designers calculated different quantities insulators and used different types supports But if you approach the issue comprehensively and determine the voltage according to all the criteria described in the article, then you can quite accurately determine the voltage class. If you are far from the electric power industry, then for a 100% determination of the power line voltage, it is still better for you to contact your local energy company.

Electricity is the main form of energy used everywhere these days. Its widespread use became possible thanks to electrical networks that connect sources and consumers of electricity. Power lines, or power lines for short, perform the function of transporting electricity. They are laid either above the surface of the earth and are called “aerial”, or buried in the ground and or under water and are called “cable”.

Overhead power lines, despite their complex infrastructure, are cheaper than cable lines. The high-voltage cable itself is an expensive and complex product. For this reason, these cables are laid only in some sections of the overhead power line route in places where it is impossible to install supports with wires, for example through sea straits, wide rivers, etc. Cables are laid electrical networks in populated areas where the construction of supports is also impossible due to urban infrastructure.

Power lines, despite their great length, are still the same electrical circuits, for which Ohm's law applies in the same way as for the others. Therefore, the efficiency of power transmission lines is directly related to the increase in voltage in it. The current strength decreases, and with it the losses become less. For this reason, the further consumers are located from the power plant, the higher the high-voltage power line should be. Modern ultra-long-distance power lines transmit electrical energy with voltages of millions of volts.

But increasing voltage to reduce losses has limitations. They are caused by corona discharge. This phenomenon manifests itself, causing noticeable energy losses, starting with voltages above 100 kilovolts. The buzzing and crackling of high-voltage wires is a consequence of corona discharge on them. For this reason, in order to reduce corona losses, starting from 220 kilovolts, two or more wires are used for each phase of an overhead power line.

The length of power lines and their operating voltage are interconnected.

• Ultra-long-distance power lines operate with voltages from 500 kilovolts.
• 220 and 330 kilovolts are voltages for main power lines.
• 150, 110, and 35 kilovolts are the voltages of distribution power lines.
• Voltages of 20 kilovolts and less are typical for local power grids through which end consumers are supplied with electricity.

Wire supports

In addition to wires, power transmission lines also include supports as the main structural elements. Their purpose is to hold wires. Each power line has several types of supports, as shown in the image below:

Anchor supports perceive heavy loads and therefore have a strong, rigid structure, which can be very diverse. All supports come into contact with soft or damp soil through a concrete foundation. Wells are made in solid soil into which power line supports are directly immersed. Examples of metal anchor support designs are shown in the image below:

The supports can also be made using concrete or wood. Wooden supports, although less durable, are one and a half times cheaper in comparison with metal and concrete structures. Their use is especially justified in regions with severe frosts and large reserves of wood. Wooden poles are most widely used in electrical networks with voltages up to 1000 Volts. The design of such supports is shown in the image below:

Power line wires

The wires of modern power lines are mainly made of aluminum wire. Pure aluminum wires are used for local power lines. The limitation is the span length between the supports is 100 - 120 meters. For longer spans, wires made of aluminum and steel are used. Such a wire has a steel cable inside, covered with aluminum conductors. The cable takes mechanical load, aluminum – electrical load.

All-steel wires are used only in short sections, where maximum strength is required with minimal wire weight. All power lines with voltages above 35 kilovolts are equipped with a steel cable to protect against lightning strikes. Wires made of copper and bronze are currently used only in power lines for special purposes. Copper and aluminum wire are used to make hollow tubular wires. This is done to reduce corona losses and reduce radio interference. Images of wires of various designs are shown below:

The wire for power lines is selected taking into account the operating conditions and the resulting mechanical loads. In the warm season, it is the wind that swings the wires and increases the breaking load. In winter, ice is added to the wind. The weight of a layer of ice on the wires significantly increases the load on them. Moreover, a decrease in temperature leads to a decrease in the length of the wires and increases the internal stress in their material.

Insulators and fittings

For secure connection Insulators are used for wires with supports. The material for them is either electrical porcelain or tempered glass, or polymer, as shown in the image below:

Glass insulators under the same conditions are smaller and lighter than porcelain insulators. Structurally, insulators are divided into pin and pendant. The pin design is not used for power lines with voltages above 35 kilovolts. The mechanical loads absorbed by suspension insulators are greater than those of pin insulators. For this reason, the suspended structure can be used for more low voltage instead of pin insulators.

The hanging insulator consists of individual cups connected into a garland. The number of cups depends on the power line voltage. To connect the cups into a garland and all other fastenings of wires and insulators, special fittings are used. Reliability, strength and durability in an open environment are determined by such materials for the manufacture of fittings as steel and cast iron. If it is necessary to obtain increased corrosion resistance, parts are coated with zinc.

The fittings include various clamps, spacers, vibration dampers, coupling connectors, intermediate insulator links, and rocker arms. A general idea of ​​the fittings is given by the image below:

Protective devices

Another component of power transmission lines is structures that protect equipment connected to power lines from atmospheric and switching overvoltages. Protection against lightning strikes is provided by a cable stretched above all the wires of the power line and lightning rods, which are usually installed near substations. Protective gaps are located on power transmission line supports. An example of such a gap is shown in the image on the left. Tubular arresters are installed near substations, in which there is a spark gap inside. If it breaks through and an arc occurs, powered by a short circuit current, a gas is released that extinguishes this arc.

All technical and organizational nuances for the installation of power lines are regulated by the Rules for the Construction of Electrical Installations (PUE). Any deviations from these rules are strictly prohibited and may be considered a crime of varying severity depending on the consequences.

Representing the then vision of transitioning Europe to renewable energy. The basis of the EU’s “green energy” was supposed to be thermal power plants with a concentration of solar energy, located in the Sahara Desert, capable of storing energy at least for the evening peak of consumption, when conventional photovoltaics no longer work. A feature of the project was to be the most powerful power transmission lines (PTLs) for tens of gigawatts, with a range of 2 to 5 thousand km.

SPPs of this kind were to become the main European renewable energy sector.

The project lasted for about 10 years, and then was abandoned by the founding concerns, since the reality of European green energy turned out to be completely different and more prosaic - Chinese photovoltaics and ground-based wind generation located in Europe itself, and the idea of ​​stretching energy highways through Libya and Syria was too optimistic .

Power lines planned within desertec: three main directions with a capacity of 3x10 gigawatts (in the picture one of more weak versions with 3x5) and several submarine cables.

However, it was not by chance that powerful power lines arose in the desertec project (it’s funny, by the way, that the area of ​​land under power lines in the project turned out to be larger than the area of ​​land under SES) - this is one of key technologies, which can allow RES generation to grow to an overwhelming share, and vice versa: in the absence of technology for transmitting energy to long distances RES are quite possibly doomed to account for no more than 30-40% of Europe's energy sector.

The mutual synergy of transcontinental power lines and renewable energy sources is quite clearly visible in models (for example, in the giant LUT model, as well as in the model of Vyacheslav Laktyushin): the unification of many wind generation areas located 1-2-3 thousand kilometers from each other destroys the mutual correlation of the level generation (dangerous due to general failures) and equalizes the amount of energy entering the system. The only question is at what cost and with what losses is it possible to transmit energy over such distances. The answer depends on different technologies, of which today there are essentially three: transmission by alternating current, direct current and via a superconducting wire. Although this division is a little incorrect (a superconductor can be with alternating and direct current), it is legitimate from a system point of view.

However, the technology for transmitting high voltage voltage, in my opinion, is one of the most fantastic-looking. The photo shows a 600 kV rectifier station.

Traditional electric power industry from the very beginning followed the path of combining power generation using high-voltage power lines with alternating current, reaching 750-800-kilovolt power lines in the 70s, capable of transmitting 2-3 gigawatts of power. Such power lines have reached the limits of the capabilities of classical networks AC: on the one hand, on system limitations, associated with the complexity of synchronizing networks with a length of many thousands of kilometers and the desire to divide them into energy regions connected by relatively small safety lines, and on the other hand, due to the increase reactive power and losses of such a line (due to the fact that the inductance of the line and capacitive coupling to the ground increases).

This is not a very typical picture in the Russian energy sector at the time of writing, but usually flows between regions do not exceed 1-2 GW.

However, the appearance of energy systems in the 70s-80s did not require powerful and long-distance power lines - it was most often more convenient to move a power plant closer to consumers, and the only exception was the then renewable energy sources - hydrogeneration.

Hydroelectric power plants, and specifically the Brazilian project of the Itaipu hydroelectric power station in the mid-80s, led to the emergence of a new champion in the transmission of electricity far and wide - power lines DC. The power of the Brazilian link is 2x 3150 MW at a voltage of +-600 kV for a range of 800 km, the project was implemented by ABB. Such capacities are still on the verge of available AC power lines, but larger losses paid for the project with conversion to DC.

The Itaipu hydroelectric power station with a capacity of 14 GW is still the second largest hydroelectric power station in the world. Part of the generated energy is transmitted via an HVDC link to the area of ​​Sao Paolo and Rio de Janeiro.

Comparison of alternating (AC) and direct (DC) power lines. The comparison is a bit promotional, because... with the same current (say 4000 A), an 800 kV AC power line will have a capacity of 5.5 GW versus 6.4 GW for a DC power line, albeit with twice the losses. With the same losses, the power will actually differ by 2 times.

Calculation of losses for different options Power lines that were supposed to be used in the Desertec project.

Of course, there are disadvantages, and significant ones. First, direct current in an AC power system requires rectification on one side and "curling" (i.e., generation of a synchronous sine wave) on the other. When we are talking about many gigawatts and hundreds of kilovolts, this is performed with very non-trivial (and very beautiful!) equipment, which costs many hundreds of millions of dollars. In addition, until the beginning of the 2010s, DC power lines could only be of the “point-to-point” type, since there were no adequate switches for such DC voltages and powers, which means that if there were many consumers, it was impossible to cut off one of them with a short circuit - just extinguish the entire system. This means that the main use of high-power PT power lines is the connection of two energy regions where large flows were needed. Just a few years ago, ABB (one of the three leaders in the creation of HVDC equipment) managed to create a “hybrid” thyristor-mechanical switch (similar in ideas to the ITER switch) that is capable of such work, and now the first high-voltage DC power line “point-to-point” is being built multipoint” North-East Angra in India.

Nevertheless, DC energy technology developed and became cheaper (largely thanks to the development of power semiconductors), and by the advent of gigawatts of renewable energy generation it was quite ready to begin connecting remote powerful hydroelectric power stations and wind farms to consumers. Especially many such projects have been implemented in recent years in China and India.

However, the idea goes further. In many models, the power transmission capabilities of DC power transmission lines are used to level out RES variability, which is the most important factor towards the introduction of 100% RES in large power systems. Moreover, this approach is already being implemented in practice: we can give an example of a 1.4 gigawatt Germany-Norway link, designed to compensate for the variability of German wind generation by Norwegian pumped storage power plants and hydroelectric power stations, and a 500 megawatt Australia-Tasmania link needed to maintain the energy system of Tasmania (mainly powered by hydroelectric power stations) in drought conditions.

Much of the credit for the spread of HVDC also goes to progress in cables (since HVDC are often marine projects), which over the past 15 years have increased the available voltage class from 400 to 620 kV

However, further dissemination hampered by both the high cost of power lines themselves of this caliber (for example, the world's largest power line PT Xinjiang - Anhui 10 GW for 3000 km will cost the Chinese approximately 5 billion dollars), and the underdevelopment of equivalent areas of renewable energy generation, i.e. the absence of comparable large consumers around large consumers (for example, Europe or China) at a distance of up to 3-5 thousand km.

Including about 30% of the cost of power transmission lines of PT lines are such converter stations.

However, what if power line technology appears at the same time cheaper and with lower losses (which determine the maximum reasonable length?). For example, a power line with a superconducting cable.

An example of a real superconducting cable for the AMPACITY project. In the center there is a former with liquid nitrogen, on it there are 3 phases of superconducting wire made of tapes with a high-temperature superconductor, separated by insulation, on the outside there is a copper screen, another channel with liquid nitrogen, surrounded by multilayer screen-vacuum thermal insulation inside the vacuum cavity, and on the outside - a protective polymer shell .

Of course, the first projects of superconducting power lines and their economic calculations appeared not today or yesterday, but in the early 60s, immediately after the discovery of “industrial” superconductors based on niobium intermetallic compounds. However, for classical networks without renewable energy sources there was no place for such SP power lines - both from the point of view of the reasonable power and cost of such power lines, and from the point of view of the volume of developments needed to put them into practice.

Superconducting cable line project from 1966 - 100 GW per 1000 km, with a clear underestimation of the cost of the cryogenic part and voltage converters

The economics of a superconducting line are determined essentially by two things: the cost of the superconducting cable and the energy lost for cooling. The initial idea of ​​​​using niobium intermetallic compounds stumbled over the high cost of cooling with liquid helium: the internal “cold” electrical assembly must be kept in a vacuum (which is not so difficult) and additionally surrounded by a screen cooled with liquid nitrogen, otherwise the heat flux at a temperature of 4.2 K will exceed the reasonable power of refrigerators. This “sandwich” plus the presence of two expensive cooling systems at one time buried interest in SP-power lines.

A return to the idea occurred with the discovery of high-temperature conductors and the “medium-temperature” magnesium diboride MgB2. Cooling at a temperature of 20 Kelvin (K) for diboride or at 70 K (with 70 K being the temperature liquid nitrogen- has been widely developed, and the cost of such a refrigerant is low) looks interesting for HTSC. Moreover, the first superconductor today is fundamentally cheaper than HTSC tapes produced by semiconductor industry methods.

Three single-phase superconducting cables (and cryogenic feedthroughs in the background) from the LIPA project in the USA, each with a current of 2400 A and a voltage of 138 kV, for a total power of 574 MW.

Specific figures for today look like this: HTSC has a conductor cost of 300-400 dollars per kA*m (i.e., a meter of conductor that can withstand kiloamperes) for liquid nitrogen and 100-130 dollars for 20 K, magnesium diboride for a temperature of 20 K has cost 2-10 $ per kA*m (the price has not settled, like the technology), titanium niobate - about 1 $ per kA*m, but for a temperature of 4.2 K. For comparison, aluminum power line wires cost ~5-7 dollars per kA*m, copper - 20.

Real heat losses of AMPACITY SP cable 1 km long and ~40 MW power. In terms of the power of the cryocooler and circulation pump, the power spent on cable operation is about 35 kW, or less than 0.1% of the transmitted power.

Of course, the fact that an SP cable is a complex evacuated product that can only be laid underground adds additional costs, however, where land for power lines costs significant money (for example, in cities), SP power lines are already beginning to appear, albeit for now in the form of pilot projects. Basically, these are cables made of HTSC (as the most developed), for low and medium voltages (from 10 to 66 kV), with currents from 3 to 20 kA. This scheme minimizes the number of intermediate elements associated with increasing the voltage in the main line (transformers, switches, etc.) The most ambitious and already implemented power cable project is the LIPA project: three cables 650 m long, designed for transmission three-phase current with a capacity of 574 MVA, which is comparable to a 330 kV overhead power line. The most powerful HTSC cable line to date was commissioned on June 28, 2008.

An interesting AMPACITY project was implemented in Essen, Germany. A medium voltage cable (10 kV with a current of 2300 A with a power of 40 MVA) with a built-in superconducting current limiter (this is an actively developing interesting technology that allows, due to the loss of superconductivity, to “naturally” disconnect the cable in the event of short circuit overloads) installed inside an urban area. The launch took place in April 2014. This cable will become a prototype for other projects planned in Germany to replace 110 kV power line cables with 10 kV superconducting cables.

Installing an AMPACITY cable is comparable to pulling conventional high-voltage cables.

Experimental projects with different superconductors on different meanings even more current and voltage, including several carried out in our country, for example, testing an experimental 30-meter cable with an MgB2 superconductor cooled by liquid hydrogen. The cable for a direct current of 3500 A and a voltage of 50 kV, created by VNIIKP, is interesting due to its “hybrid scheme”, where cooling with hydrogen is at the same time a promising method of transporting hydrogen within the framework of the idea of ​​“hydrogen energy”.

However, let's return to renewable energy sources. LUT modeling was aimed at creating 100% renewable energy generation on a continental scale, while the cost of electricity should be less than $100 per MWh. The peculiarity of the model is the resulting flows of tens of gigawatts between European countries. It is almost impossible to transmit such powers in any way other than SP DC power lines.

LUT modeling data for the UK calls for electricity exports of up to 70 GW, with the island's 3.5 GW links available today and expanding to 10 GW in the foreseeable future.

And similar projects exist. For example, Carlo Rubbia, familiar to us from the reactor with an accelerator driver MYRRHA, is promoting projects based on almost the only manufacturer of magnesium diboride strands in the world today - according to the idea, a cryostat with a diameter of 40 cm (however, the diameter is already quite difficult to transport and lay on land ) accommodates 2 cables with a current of 20 kA and a voltage of +-250 kV, i.e. with a total power of 10 GW, and in such a cryostat you can place 4 conductors = 20 GW, which is already close to that required by the LUT model, and unlike conventional high-voltage DC lines, there is still a large margin for increasing power. Power consumption for refrigeration and pumping hydrogen will be ~10 megawatts per 100 km, or 300 MW per 3000 km - about three times less than for the most advanced high-voltage direct current lines.

Rubbia's proposal for a 10-gigawatt cable transmission line. Such a gigantic pipe size for liquid hydrogen is needed in order to reduce hydraulic resistance and be able to install intermediate cryostations no more than 100 km away. There is also a problem with maintaining a vacuum on such a pipe (a distributed ion vacuum pump is not the wisest solution here, IMHO)

If we further increase the dimensions of the cryostat to values ​​typical for gas pipelines (1200 mm), and lay 6-8 conductors of 20 kA and 620 kV inside (the maximum voltage for cables developed to date), then the power of such a “pipe” will already be 100 GW, which exceeds the capacity transmitted by the gas and oil pipelines themselves (the most powerful of which transmit the equivalent of 85 GW of thermal power). The main problem may be connecting such a highway to existing networks, however, the fact is that the technology itself is almost available.

It would be interesting to estimate the cost of such a line.

The construction part will obviously dominate. For example, laying 800 km 4 HVDC cables in the German Sudlink project will cost ~8-10 billion euros (this is known, since the project increased in price from 5 to 15 billion after the transition from overhead line to cable). The cost of laying 10-12 million euros per km is approximately 4-4.5 times higher than the average cost of laying gas pipelines, judging by this study.

In principle, nothing prevents the use of similar technology for laying heavy-duty power lines, however, the main difficulties here are visible in the terminal stations and connection to existing networks

If we take something in between gas and cables (i.e. 6-8 million euros per km), then the cost of the superconductor will most likely be lost in the cost of construction: for a 100-gigawatt line, the cost of the joint venture will be ~$0.6 million per 1 km, if you take the joint venture cost 2$ per kA*m.

An interesting dilemma emerges: joint venture “megamains” turn out to be several times more expensive than gas mains with comparable capacity (let me remind you that this is all in the future. Today the situation is even worse - we need to recoup R&D on joint venture power lines), and that is why gas pipelines are built, but not joint ventures -Power lines. However, as renewable energy sources grow, this technology may become attractive and undergo rapid development. Already today, the Sudlink project would probably be implemented in the form of a SP cable, if the technology were ready. Add tags

October 6 at Kaliningrad region presented the tallest stylized power lines in Russia. There are no analogues of the design made in the form of anchors in the country. The 112-meter-high object is installed in a place of active shipping, on the banks of the Pregolya River.

Towers are part of a power transmission line that is built to technological connection Pregolskaya TPP (440 MW) with the existing 330 kilovolt Severnaya substation. The work is being carried out as part of the program for the development and reconstruction of the electrical grid complex until 2020.

The supports were manufactured according to an individual project by the Gidromontazh Pilot Plant, and the installation was carried out by the Setstroy company.

One of the first ships to pass under the power lines between the supports was one of the largest sailing ships - the four-masted bark Kruzenshtern, whose masts are about 55 meters high.

“We entered the Russian Book of Records because these are the tallest stylized high-voltage poles in the Russian Federation. These are not just metal structures, this is an active 330 kilovolt power line. The goal itself was not to build an anchor, this is a consequence of our work on reliable and safe energy supply to consumers in the region,” said the chairman of the board of directors of Yantarenergo (part of Rosseti PJSC) at the presentation.

He added that the application has already been sent to Interrecord. After emissaries arrive in Kaliningrad and take measurements, a new unique engineering project - stylized anchor-shaped supports - will be able to claim a world record.

The height of the support is comparable to the height of a 36-story building or the length of a football field and is 112 meters, each of the two supports consists of five tiers, the width of the anchors is more than 16 meters. The support weighs 450 tons and can withstand winds of up to 36 meters per second. Signal lighting is installed along the entire height of the supports, which makes them visible to ships and aircraft at night. The reliability of the structure is ensured by almost 270 piles driven to a depth of 24 meters.

The distance between the supports above the Pregolya River, in a place of active navigation, is about 500 meters, the height of the suspension lines of more than 60 meters was chosen in order to ensure the passage of the largest vessels, such as the sailing ships "Kruzenshtern" and "Sedov", so that the crew of the barks, home port which Kaliningrad is, did not have to fold the masts.

The project was developed by the Gidromontazh plant, the only enterprise in Russia that specializes in the creation of non-standard power lines. The same enterprise produced decorative power line supports in the shape of a snow leopard and skiers - symbols of the 2014 Olympics in Sochi, as well as the first stylized Yantarenergo power line support in the form of the Zabivaki wolf, installed in preparation for the 2018 World Cup.

As Yantarenergo said, the highest power transmission line supports in Russia in the form of an anchor are part of a large-scale project: to connect the new Pregolskaya TPP, which was built but has not yet been fully put into operation, a new power transmission line with a length of 65 kilometers was built from the Severnaya substation. An energy bridge of 254 pillars will create a ring around the regional center. Some of the lines pass over the Pregolya River, in places of active shipping, where unique supports were built.