Patent ID: 6144567
Filing Date: 2000-11-07
Classification: H02J,H02M,Y02E

Abstract:
A plant for transmitting electric power comprising:at least first and second VSC-converters, each adapted to convert direct voltage into alternating voltage and convert alternating voltage into direct voltage, and each having an alternating voltage side to which at least one phase of an alternating voltage network is connected and a direct voltage side having first and second poles with a direct voltage thereacross;each of said VSC-converters being connected to first and second DC/DC-converters, respectively, each of said first and second DC/DC-converters having two current valves connected in series and an inductance connected to a midpoint therebetween;said first DC/DC-converter being connected through said inductance to said first pole in said first VSC-converter and through a first output terminal connected to one of the current valves and to said second pole in said first VSC-converter;said second DC/DC-converter being connected through said inductance to said first pole in said second VSC-converter and through a first output terminal connected to one of the current valves and to said second pole in said second VSC-converter;whereby an unbalanced step-up-transformation of the direct voltage between the two poles in each of said first and second VSC-converters is produced while obtaining a potential of a higher magnitude on a second output terminal of each of said first and second DC/DC-converters, respectively, connected to the other current valve than on said first output terminal; and whereinsaid second poles of said first and second VSC-converters are each connected to an output terminal of a first additional said DC/DC-converter in common thereto, the inductance of said first additional DC/DC converter being connected to ground for defining a zero potential level, and wherein poles having opposite polarities form said second poles of said first and second VSC-converters and said first and second DC/DC-converters are adapted to deliver potentials having mutually opposite polarities on the second output terminals thereof.