China’s State Grid Corp Crushes Power Transmission Records

Jeffrey Cuebas

China’s principal grid operator has energized its largest and most potent line but, a one.one-million-volt immediate current (DC) behemoth that crushes entire world documents for voltage, distance and power.

The new extremely-superior voltage DC (UHVDC) line crafted by Beijing-primarily based Point out Grid Corporation of China can transmit up to 12 gigawatts. That is adequate to power 50 million Chinese households, according to a statement issued in Chinese by Point out Grid very last week, and 50 % a lot more than most of the 800-kilovolt UHVDC strains that Point out Grid has crafted around the earlier 10 years.

The new 1100-kv UHVDC line absorbs the grid’s alternating current at an AC/DC converter station in close proximity to the capitol of Xinjiang—China’s vast northwestern territoryand sends DC power to a next converter station in Anhui province in japanese China. That three,293 kilometer run extends power transmission’s distance record by around 900 kms.

Point out Grid dubs it the “Power Silk Road” in its statement since it follows the eponymous historical route’s path via northwest China’s Hexi Corridor and can exchange the equivalent of 25,000 coal trains’ worth of coal-fired technology in China’s closely polluted japanese towns. In addition to battling air air pollution, it could also produce a significant reduction in greenhouse fuel emissions if Point out Grid prioritizes export of the northwest’s abundant solar and wind power.

Jin Zhang, a senior engineer and deputy division head in Point out Grid’s DC transmission undertaking section, advised IEEE Spectrum during interviews in Beijing very last yr that Point out Grid commenced building 1100-kv UHVDC technologies a lot more than a 10 years ago. They recognized, he explained, that China would have to have to transfer power farther around distances that would incur substantial losses on 800-kv strains.

Early risk-profit reports determined 1100-kv as the optimum future move, said Zhang, in element since of the large AC transformers that mediate amongst the converter stations and the bordering AC grids. Installing a lesser number of substantial transformers is most expense-effective, he explained, but for a 1200-kv converter station these types of transformers may well be not possible to produce from factories.

The transformers at Point out Grid’s freshly-energized 1100-kv converter stations are movable, but they are barely little. Zurich-primarily based ABB, which delivered some of the new line’s parts together with Munich-primarily based Siemens and a number of Chinese suppliers, states transformers it crafted for Point out Grid’s undertaking weigh 800 metric tons, and extend to 37 meters in length. 1 of Point out Grid’s domestic suppliers, TBEA, established up UHV transformer manufacturing in Xinjiang to lessen transport prices.

Supersizing was also essential for other 1100-kv parts, these types of as power strains and transmission towers, to deal with the system’s unprecedented electromagnetic fields. Magnus Callavik, standard supervisor of Beijing-primarily based ABB Sifang Energy Program Co., a joint venture that delivered one established of AC/DC converters for the new line, states the 300-kv jump from 800-kv essential a “completely new” design and style.

“It sounds like you’re only incorporating an incremental element,” Callavik explained. “But it’s very demanding for insulation design and style, construction and fat of the total design and style, [additionally] system aspects these types of as how you integrate with the transformer and other programs.”

Zhang pointed to the bushings that have DC power amongst each individual station’s digital converters, housed indoors, and the UHVDC transmission strains outside the house. The bushings continue to keep electric power from flashing around to the converter halls’ walls. With the move up from 800-kV, Zhang explained they grew by half a meter to roughly one.three meters in diameter and from beneath 20 meters in length to around thirty meters. “Higher voltage signifies bigger impulse degrees, largely during switching. So we have to have for a longer period air clearances,” explained Zhang.

UHVDC technologies is seen by Chinese president Xi Jinping as a key technologies for his “Belt and Road” international progress plan. And at the UN’s 2015 Sustainable Advancement Summit Xi proposed the building of intercontinental power hyperlinks to massively scale-up cross-border sharing of renewable strength.

But UHVDC also has an critical job to engage in domestically, where by Xi has promised to change China’s skies blue once again. Particularly, Xi has committed to ending rampant wastage of renewable power technology, whereby wind, solar and hydro power crops are intentionally shut off because of to grid capability and security boundaries or to merely make home for coal-fired technology.

Point out Grid’s new 1100-kv line could assistance cut down renewable strength curtailment because Xinjiang’s wind and solar power crops are amid China’s most significant and also the country’s most closely curtailed. Additional than one-fifth of Xinjiang’s solar producing possible and one-quarter of its wind power was squandered in 2017, according to Chinese authorities studies. Sending that power to japanese China as a substitute of squandering it would assistance Point out Grid fulfill Xi’s assure to shrink curtailment to less than 5 % in all areas by 2020.

Point out Grid is working hard to fulfill that goal, according to Zhang. Whilst 12-gigawatts of new coal power technology was prepared together with Point out Grid’s 1100-kv UHVDC undertaking, Zhang advised Spectrum that a lot of of the predicted crops were being cancelled. “At minimum a lot more than half will be renewable power,” he explained of the power exports the new line will have.

1 a lot more question hangs around the effects of Point out Grid’s 1100-kv technologies: whether its large power flows can be properly built-in with China’s congested japanese grids. Challenges linked with absorbing power injected by large DC strains led to the crack-up of China’s southern grid in 2016. Point out Grid is counting on a different major UHV innovation — its increasing network of 1000-kv AC strains — to solve that challenge.

This article was up-to-date on fifteen January. 

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