High voltage dc transmission lines are one way to reduce the amount of power lost in transmission grids from the current average of about 8% to an estimated 1 to 2%, according to Wolfgang Dehen, chief executive of Siemens’ energy unit.
HVDC (High voltage direct current) transmission lines connect two separate high voltage ac systems by a dc link. The basic principle of operation of an HVDC system is based on the conversion of ac-to-dc on one end and them dc-to-ac on the user end by means of converter equipment using power thyristors.
Traditional lines typically lose 8% of power in transmission, leading to higher costs and lower earnings for energy companies. New technology, such as high-voltage direct current, trims the amount of power lost so associated costs also drop, according to Dehen.
He says it is possible to connect cities with distant renewable wind and water farms, and cited the 2,000 km HVDC transmission lines under construction in China. The line will link the Xiangjiaba hydro-electric power plant in the south west to Shanghai on the north-east coast by year’s end. “It’s definitely a higher cost cable, but it’s the only way to bridge the distance and transport large amounts of power from a generation center to users,” he says.
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