“In the 40 years since the 1980s, we have been subject to foreign control for a long time in terms of key equipment and key technologies of DC power transmission. Today, we finally won this turnaround battle, using the UHV flexible cables made by the Chinese themselves. Straight through the wall casing!” On June 11, the Liuzhou Converter Station of the Guangdong-Guangxi UHV Multi-terminal Flexible DC Demonstration Project (hereinafter referred to as “Kunliulong DC Project”) was sent to the Wudongde Power Station. The ±800kV flexible straight-through wall casing was successfully put into operation and operated stably. The deputy general manager of the Liuzhou Bureau of the UHV Company felt extremely rigid and proud.

The successful operation of this equipment means that my country has completely broken through the technical blockade of foreign countries in the aspect of UHV flexible DC wall bushing, and has achieved a technological breakthrough from scratch. This can not only improve the independent and controllable level of the main grid of West-to-East power transmission, but also signify that my country has achieved new major phased achievements in the research and development of large-scale high-end power equipment, which is very important for driving domestic industrial technology upgrades and solving core technology “stuck necks”. Puzzles are important.

As the key equipment in the UHV project, the flexible DC wall bushing is the only channel between the valve hall and the DC field of the UHV converter station. “The flexible DC through-wall bushing is equivalent to the ‘throat’ of the DC transmission system and is the only channel for DC current to enter and exit the valve hall. It can’t work normally.” said Chen Huan, deputy general manager of the innovation and digitalization department of the ultra-high voltage company.

However, the key core technology of DC through-wall bushings has always been in the hands of a few foreign manufacturers. my country has long relied on foreign imports and has no right to speak on the price. The import price of a piece of equipment is as high as tens of millions of yuan. Not only that, in the event of a serious failure of the equipment, it can only be returned to foreign manufacturers for maintenance. The maintenance time and cycle are not easy to determine, and the work is very passive.

Only by insisting on innovation and realizing technological self-reliance and self-improvement can we not be controlled by others. From the 100% dependence on imports of Tianguang DC project, to the world’s first UHV autonomous demonstration project – Yunguang DC project, and then to the world’s first ±800kV multi-terminal flexible UHV transmission project, China Southern Power Grid has continued to Promote the independent localization of DC transmission technology, lead UHV into a new era of flexible DC, and move forward step by step towards self-reliance and self-improvement in technology.

At the beginning of the Kunliulong DC project, in order to solve the “stuck neck” problem of domestic DC transmission technology, the independent research and development of flexible straight-through wall bushings was put on the agenda by China Southern Power Grid Corporation. The goal is to not only realize the localization of the bushing, but also It has better performance than imported products, and realizes the leap from “follower” to “leader” of key DC equipment. To this end, China Southern Power Grid Corporation took the lead in coordinating industry-university-research resources, selected 27 technical backbones, and formed an innovation consortium with China Xidian Group and Xi’an Jiaotong University. As a joint research and development unit of equipment, China XD Group has conquered many core technologies such as process control of large-diameter adhesive-impregnated paper capacitor cores, casing design under the action of electrical, thermal, and mechanical fields, ensuring the smooth progress of key tasks. .

After 14 months of continuous research, the joint R&D team finally successfully completed the independent research and development of the first set of flexible straight-through wall bushings, and successfully passed the appraisal.

“Compared with the existing similar imported bushings, our current carrying capacity has increased by 10%, the insulation margin has increased by 9%, and the mechanical strength has increased by 50%. The key indicators are better than similar imported equipment.” According to According to the technical experts of the R&D project team, the ±800kV flexible DC wall bushing has formed rich technical and intellectual property achievements, and cultivated 24 core patents.

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Post time: Feb-11-2022