Southern Hami–Zhengzhou

The Southern Hami–Zhengzhou UHVDC (Ultra High-Voltage Direct Current) project is an advanced power transmission system in China. It spans 2,210 kilometers from Hami in Xinjiang to Zhengzhou in Henan, passing through multiple provinces including Gansu, Shaanxi, Ningxia, and Shanxi.

This UHVDC line operates at ±800 kV, and has a transmission capacity of 8,000 MW, which was the highest in the world at the time of its construction.

Construction of the Southern Hami–Zhengzhou UHVDC began on May 13, 2012, and it was commissioned in January 2014. The project cost approximately 23.4 billion yuan, equivalent to about 3.5 billion USD or roughly 1.8 million USD per kilometer.

The transmission line starts at the Hami Nanhu converter station, located next to the Dananhu Power Station in Xinjiang. At the receiving end, it terminates at the Zhengzhou converter station in Henan. The project is owned by the State Grid Corporation of China and operated by the Northwest China Grid Company.

Technically, the Southern Hami–Zhengzhou UHVDC project includes AC filters at both converter stations to manage reactive power compensation. Specifically, 16 groups of AC filters are installed at the Hami station, providing a total reactive power compensation capacity of 3,880 Mvar. The Zhengzhou station has 19 groups of AC filters with a total capacity of 4,940 Mvar.

To address potential resonance issues, a group of blocking filters tuned to 50 Hz is installed on the neutral line of the Hami station. This uses a 50 mH coil to form a resonant circuit.

The project's minimum power transmission capacity is 8000 MW during bipolar operation and 4000 MW during monopolar operation.

ABB, a major supplier for the project, provided converter transformers, HVDC converter valves, bushings, tap changers, DC circuit breakers, wall bushings, and capacitors. Each transformer supplied by ABB is 32 meters long and weighs approximately 800 tons.

The Southern Hami–Zhengzhou UHVDC project is part of China's efforts to transmit power from resource-rich western regions to energy-hungry eastern areas. It enables the integration of renewable energy sources, particularly wind and solar power from Xinjiang, into the national grid. This project demonstrates China's commitment to developing advanced power transmission technologies and improving its national energy infrastructure.