Photo: Screenshot of west-to-east power transmission project

The first convertor transformer using China-made on-load tap changers have successfully been put into operation on Sunday at a crucial west-to-east power transmission project located in South China's Guangdong Province, according to a report published by xinhuanet.com. 

Feng Dong, a senior executive at a subsidiary of the China Southern Power Grid, was quoted by the report as saying that China had completed the technological breakthrough from scratch in field of convertor transformer on-load tap changers, and has achieved full localization of components and other products' industrial chains.

This marks the fact that China has officially broken through the restrictions of this core technology in high-end electric equipment, Feng said.

Previously, long-distance, large capacity and high voltage direct current facilities are required for the transmission of electricity from western to eastern areas in China, and both terminals for transmitting and receiving power need to use the equipment of converter transformer that weighs more than 300 tons.

On-load tap changers of a convertor transformer are used to adjust the voltage, power load and current, similar to the function of a gearbox in a car. 

Deng Jun, a senior technical expert at the aforementioned company, also said that an on-load tap changer of a convertor transformer has about 1,000 components, and is a highly complex and sophisticated piece of equipment.

According to the Xinhua report, this technology used to be grasped by only a few overseas companies, and when technical fault took place previously, Chinese companies had no choice but to replace the products with imported goods of the same model, whose ordering cycle took about three to four months, thus posing challenges to the safety of power operation in the country. 

The report also cited a deputy general manager of the company as saying that the company has established a team in partnership with upper stream and downstream companies along the industrial chains. 

After more than two years' of efforts, the team has broken through vacuum switch tubes and other technical bottlenecks to successfully research the large capacity convertor transformer on-load tap changer with rated capacity of 6,000 kilovolt-ampere, maximum voltage of 6,000 volt and maximum rated current of 1,300 ampere.

Using the domestically made on-load tap changers could save nearly 40 million yuan ($5.56 million) In the building of ultra-high voltage direct current power transmission projects, the manager said.