What is UHVDC? What drives UHV development in China? What are the challenges?

Summary

• The Siemens Ultra High Voltage DC System  is the latest developed system with a new dimension of efficiency in HVDC transmission.

• The Siemens Ultra High Voltage DC System is a newly developed system that ensures increased performance and robustness of the transmission grid during periods of steadily growing energy demand.

• It provides a single bipole power transmission capacity of more than seven GW at a voltage of ± 800 kV, while reducing transmission losses by 60 percent compared with standard ± 500 kV HVDC. 

UHV projects are all mega-projects costing billions of dollars and with capacities of least five gigawatts each. 

Understand your incentives for UHV development

In the previous era of fast economic expansion and electricity demand growth, all the parties in the UHV chain, from both the supply and demand sides and from grid companies to governments, had incentives to support UHV development. As electricity demand growth has slowed, incremental power demand has shrunk (with negative numbers appearing in some provinces in the Northwest and

Southwest) and generation side competition has intensified.

This has resulted in destination regions displaying only lukewarm support, and even opposition, to UHV project proposals. There has been a breakdown in support from across the UHV chain.

What drives additional UHV projects?

The drivers for additional UHV projects under current market conditions are mainly the reduction of wind, solar and hydropower curtailment in the North, Northwest and Southwest, and more general support for China’s transition to a low-carbon green economy. 

The key is to find provinces willing to accept the electricity delivered by any new UHV project, a challenge that has become increasingly difficult given China’s extreme levels of excess capacity.

The performance and economics of already commissioned UHV projects may also have raised concerns with regulators. 

What are the reasons curtailing UHV projects in China?

The reasons for the low utilization of UHV projects and the fact the UHV projects have not improved the curtailment of wind and solar power are many. They have been linked to a number of factors such as power system planning for grid and generation, technologies, policies, and conflicts of interest among government departments and industrial groups. 

More at HVDC Belt and Road 2019 China Conference