The future lies in the transmission of electricity using direct current? World archipelago and its network

Today, most high-voltage power lines are based on alternating current. However, the development of new energy sources, solar and wind power plants, located far from settlements and industrial consumers, requires transmission networks, sometimes even on a continental scale. And here, as it turned out, HVDC is better than HVAC.

high voltage DC line (short for High Voltage Direct Current) have a better ability to carry large amounts of energy than HVAC (short for High Voltage Alternate Current) for long distances. Perhaps a more important argument is the lower cost of such a solution over long distances. This means that it is very useful for providing electricity over long distances from renewable energy locations that connect islands to the mainland and even potentially even different continents to each other.

HVAC line require the construction of huge towers and traction lines. This often causes protests from local residents. HVDC can be laid any long distance underground, without the risk of large energy lossesas is the case with hidden AC networks. This is a slightly more expensive solution, but it is a way to avoid many of the problems that transmission networks face. Of course, for transmission from Columbia region existing and socially acceptable transmission lines with high pylons can be adapted. This means that you can send more energy through the same lines.

There are many problems with AC power transmission that are well known to power engineers. These include, among others generation of electromagnetic fieldsas a result, the lines are high above the ground and spaced apart from each other. There are also heat losses in the soil and water environment and many other difficulties that have learned to cope with time, but which continue to burden energy economics. AC networks require many engineering compromises, but using AC is certainly cost effective for transmission. long distance electricityso in most situations these are not unsolvable problems. However, that doesn't mean you can't use a better solution.

Will there be a global energy network?

In 1954, ABB built a sunken 96 km high voltage DC transmission line between the Swedish mainland and the island (1). How is traction allows you to get twice the voltage what's up alternating current. Underground and submarine DC lines do not lose their transmission efficiency compared to overhead lines. Direct current does not create an electromagnetic field that would affect other conductors, earth or water. The thickness of the conductors can be any, since the direct current does not tend to flow over the surface of the conductor. DC has no frequency, so it's easier to connect two networks of different frequencies and convert them back to AC.

but D.C. he still has two limitations that kept him from taking over the world, at least until recently. First, voltage converters were much more expensive than simple physical AC converters. However, the cost of DC transformers (2) is rapidly falling. Cost reduction is also affected by the fact that the number of devices using direct current on the side of energy-targeted receivers is increasing.

2. Siemens DC transformer

The second problem is that high voltage DC circuit breakers (fuses) were ineffective. Circuit breakers are components that protect electrical systems from overload. DC mechanical circuit breakers they were too slow. On the other hand, although electronic switches are quite fast, their actuation has so far been associated with large ones, as high as 30 percent. power loss. This has been difficult to overcome but has recently been achieved with a new generation of hybrid circuit breakers.

If recent reports are to be believed, we are well on our way to overcoming the technical challenges that have plagued HVDC solutions. So it's time to move on to the undoubted benefits. Analyzes show that at a certain distance, after crossing the so-called.equilibrium point» (ca. 600-800 km), the HVDC alternative, although its initial costs are higher than the start-up costs of AC installations, always results in lower overall transmission network costs. The break-even distance for submarine cables is much shorter (typically around 50 km) than for overhead lines (3).

3. Compare the investment and cost of power transmission between HVAC and HVDC.

DC terminal they will always be more expensive than AC terminals, simply because they must have components to convert DC voltage as well as DC to AC conversion. But DC voltage conversion and circuit breakers are cheaper. This account is getting more and more profitable.

Currently, transmission losses in modern networks range from 7%. up to 15 percent for terrestrial transmission based on alternating current. In the case of DC transmission, they are much lower and remain low even when the cables are laid underwater or underground.

So HVDC makes sense for longer stretches of land. Another place where this will work is the population scattered across the islands. Indonesia is a good example. The population is 261 million people living on about six thousand islands. Many of these islands are currently dependent on oil and diesel fuel. Japan has a similar problem with 6 islands, 852 of which are inhabited.

Japan is considering building two large high voltage DC transmission lines with mainland Asia.which will make it possible to get rid of the need to independently generate and manage all of their electricity in a limited geographical area with significant terrain difficulties. Such countries as Great Britain, Denmark and many others are arranged in a similar way.

Traditionally, China thinks on a scale that surpasses that of other countries. The company, which operates the country's state-owned electricity grid, has come up with the idea of ​​building a global high-voltage DC grid that will connect all the wind and solar power plants in the world by 2050. Such a solution, plus smart grid techniques that dynamically allocate and distribute power from places where it is produced in large quantities to places where it is needed at the moment, could make it possible to read "Young Technician" under the light of a lamp powered by energy generated by windmills located somewhere in the South Pacific. After all, the whole world is a kind of archipelago.