"Jiquan Direct Current" tells you how Xinjiang's electricity lights up China's nights!

Recently, good news came from the west of the motherland. The daily power transmission of the Changji-Guquan ±1100 kV UHV DC transmission project (hereinafter referred to as "Jiquan DC") has exceeded 200 million kWh, and the cumulative power transmission has exceeded 300 billion!

If the sheer magnitude of the numbers alone is not enough to give people a sense of reality, then simply translate it into the following: the electricity it delivers in one day can power 400 million 30-watt lights, or meet the annual electricity needs of about 130,000 families of four. The concept of 300 billion is even more spectacular - it is equivalent to converting more than 10,000 tons of standard coal on site and reducing carbon dioxide emissions by more than 30,000 tons. In addition, this is the third year that the Jiquan DC is expected to rank first in the country in terms of electricity delivered.

In short, Xinjiang's electricity export "artery", which has accumulated strength over time, is telling the world the Chinese story of electricity transmission in its own green and efficient way.

Jiquan Direct Current

The value of "UHV"

The Jiquan DC line, which passes through six provinces and regions with a total length of 3,293 kilometers, connects the large-scale energy base in Jungar, Xinjiang and the load center in East China. It is currently the world's ultra-high voltage transmission project with the highest voltage level, largest transmission capacity, longest transmission distance and most advanced technology. It is also an important energy channel for "West-to-East Power Transmission".

This "UHV" king can transport electricity from Xinjiang to Anhui (only an estimated distance) 30 times in the time it takes for a human to blink an eye. Without being modest, it can only be said that China can build such a "sky road" at present.

Before we praise it, perhaps we must figure out that there are tens of millions of ways to transmit electric energy, so why is "ultra-high voltage" the one that has emerged as the most popular?

If someone could use an infrared thermal imager to examine the transmission lines of Jiquan DC, they would be surprised to find that the working temperature of the conductors containing huge amounts of electricity is only about 20°C. You should know that in electrical engineering, transmission lines with AC transmission voltage levels higher than 1000 kV and DC transmission voltage levels higher than ±800 kV are called UHV transmission, but the DC transmission voltage of Jiquan DC is as high as ±1100 kV! Therefore, in other words, heat generation represents energy loss of the line. my country's "West-to-East Power Transmission" transmission lines are thousands of kilometers long, and even if the loss rate is only 1%, it will be a huge waste when accumulated. As it happens, UHV is the key to reducing circuit losses!

P (power) = I (current) * U (voltage), a simple formula found in middle school physics textbooks, can fully explain the intuitive advantages of UHV. Since the greater the current, the greater the loss when the transmission power is constant, there is only one way to reduce the current - that is "crazy" voltage boost!

Compared with traditional high-voltage transmission, the "UHV" transmission after crazy voltage boosting can meet the transmission plan of longer distance and higher power. For example, compared with 500 kV lines, 1000 kV lines can increase the transmission power by about 4 times and extend the transmission distance by 3 times, while the loss is only about 30% of that of 500 kV transmission lines, which has a very significant technical advantage. This is also the underlying logic for the formation of Jiquan DC.

But how did it rise to ±1100 kV? There is a surprise behind it - Changji Converter Station is the only "true god".

A beating heart

If you are lucky enough to visit the ±1100 kV Changji Converter Station, you will feel like you have entered the "Land of Giants". There, each device is extremely tall, with an average height of no less than several dozen meters. Whether it is a low-end converter transformer or a "giant beast" such as GIS combination electrical appliances, they all look down at humans from a high position, and at the same time, they work in an orderly manner under human control, like a power transmission heart beating on the land of the motherland.

"The converter station of the Jiquan DC project integrates many technological innovations." Deputy chief engineer of State Grid Xinjiang Construction Branch said, "Its appearance has overcome many industry-first and world-first problems, and many innovative applications of technologies, systems and equipment are groundbreaking worldwide." Among them, the converter transformer, which is as big as a six-story building, is the most eye-catching.

Inside this behemoth, there are two sets of metal coils weighing tens of tons. By adjusting their proportions, different voltages can be obtained using electromagnetic induction. Furthermore, it can also convert the alternating current from three transmission lines sent from the power plant into direct current from two transmission lines. Its capabilities should not be underestimated.

"There are many advanced equipment like this." Indeed, since 2014, State Grid Corporation of China has relied on the "863 Plan" and national key R&D plans to organize hundreds of units in the power, electronics, and machinery industries to conduct joint industry-university-research research and overcome world-class challenges such as system solution demonstration, ultra-long air gap insulation, overvoltage depth control, electromagnetic environment control, system analysis and design, reliable control and protection, main equipment development, and electromechanical collaborative design of ultra-large and complex insulation structures. It has successfully developed more than 30 types of key DC equipment in 15 categories that represent the highest level of similar international equipment.

The interior of Changji Converter Station (Source: Xinhua News Agency)

Moreover, since the line passes through the hinterland of the Guanzhong Plain in Shaanxi and the Qinling Mountains, where "clouds cross the Qinling Mountains, where is my home, snow blocks the Blue Pass, and the horses cannot move forward", the route is complex, external coordination is difficult, there are many important intersections and crossings, the construction environment is harsh, and material transportation is difficult. Therefore, Shaanxi Electric Power has specially established an unmanned area line construction command to be responsible for the construction of the unmanned section, breaking rocks and opening mountains. Through a series of deployments such as making 3D sand tables, purchasing satellite phones, and hiring helicopter emergency teams, it finally crossed the Qinling unmanned area for 15 kilometers, crossed 4 750kV power lines, 15 330kV power lines, 12 highways, 2 high-speed railways, and 9 electrified railways.

Seeing this, you may sigh, "Another miracle of ingenuity!" Or you may say to yourself, "Ah! It must be a powerful weapon of a great country!" But in fact, there is a somewhat helpless truth behind this: while the eastern part of our country is brightly lit, the western part, which is surging with a large amount of energy supply, is a relatively dim land. Because of the climate and geography, humans may be destined to not be able to live there for a long time. Only through an energy network with ultra-high voltage as the backbone can this blessed land be further explored.

Almost all the light is concentrated in the eastern part of my country.

So in the end, I still have to say the same old thing: cherish nature. Please do not be "confident" about nature under the endorsement of technological development. Make the best use of everything, starting with every little thing around you.