China’s Transmission Grid To Support Growing Economy

China’s expansive geography and increasing demand over the last decade calls for an increase in its UHV transmission capacity.
Published: Fri 08 May 2015

Power and automation technology group ABB, has won orders to the value of over $100 million to supply converter transformers and components including wall bushings and circuit breakers for the Lingzhou-Shaoxing ultrahigh-voltage direct current (UHVDC) transmission link in China.

More electricity for a growing economy

The link will be the 7th 800kV UHVDC transmission system in the country and will help to deliver more electricity from remote power plants in China’s interior to growing urban areas, over longer distances with fewer losses. The order was booked in the first quarter of 2015.

The link will transfer 8,000MW of power from Lingzhou in the northwestern Ningxia region to Shaoxing in the eastern Zhejiang province, stretching over approximately 1,700 kilometers.

This will be the world’s first 750kV ultra-high-voltage alternating current (AC) to 800kV UHVDC connection, an innovation that enhances the efficiency and capacity of long-distance UHV electricity delivery systems necessary for China’s growing economy. The products provided by ABB are scheduled to be commissioned in 2016.

China has major load centres in its eastern regions, while its energy resources are in the west and northwest. The expansive geography and increased demand over the last decade have prompted the country to increase its UHV transmission capacity, enabling delivery of power from newer, more-efficient thermal power generation plants near energy reserves while lowering pollution near cities.

“Ultra-high-voltage technology makes it possible to transmit greater amounts of power across greater distances, with minimum losses and without compromising on reliability,” said Bernhard Jucker, president of ABB Power Products division. “This innovative solution will enable the world’s first AC to UHVDC connection and will help reduce environmental impact on residents of urban areas.”

New converter tech increases capacity of UHVDC links

ABB will supply 800kV UHVDC converter transformers and components.These UHVDC transformers are based on innovative technology, for the first time connecting a 750kV AC power supply grid that collects electricity from an array of power generation plants to an 800kV UHVDC link.

Recent converter technology advances have made it possible to increase the power transmission capacity of UHVDC links to an unprecedented level, but that has moved the power bottleneck from the UHVDC side of the converter to the supplying AC side.

ABB has been able to overcome this challenge by using its UHVDC transformer technology capable of supplying the converters with electricity from a 750kV AC grid, instead of the traditional 500kV. Increasing AC voltage before it is converted to DC yields a substantial additional benefit by reducing electricity losses within the AC collecting grid.

Converter transformers play a critical role in HVDC transmission, serving as the vital interface between the DC link and the AC network.