Executives at ABB Power Systems in Ludvika, Sweden see a promising future for a new type of power system which was officially launched one year ago but is still at a very early stage of its commercial development. Given the name HVDC Light, the basic concept involves two identical converter stations connected by a newly-developed extruded DC cable.
Says Project Manager Kjell Eriksson, “much of the technology behind HVDC Light was originally part of a research program into finding an alternative to additional rotating machines as a voltage source.” Eriksson explains that this work also involved developing a new type of converter.
Apparently, while existing converter stations are suitable for their present field of application, the technology has a characteristic which does not make it appropriate for the type of applications where it is foreseen that HVDC Light would have greatest value. For example, if there is a voltage reduction in any one phase, this can lead to problems. Moreover, there is a need for a power supply. “With this new technology” points out Eriksson, “we can avoid an additional installation of a
rotating machine power source to produce phase voltages. This possibility is the direct result of the new type of converter we have developed.”
Eriksson indicates that ABB Power Systems started this work with a focus on traditional sizes of converters, i.e. 1000 MW and 600 MW. However, as the project progressed, engineers found that there would also likely be a future market for much smaller converters, in the order of 3 MW to 150 MW.
Among the principal target applications for this new technology are isolated communities, industrial installations and other areas where overhead lines are either not permitted or are not economically feasible. Typically, in these types of cases diesel generators have been used. However, this power source suffers from the drawback of fuel costs and relatively frequent maintenance requirements. According to Eriksson, other application areas for the HVDC Light concept include supplying additional power to a weak existing network, tapping from an existing line or supplying to a distributed DC network.
