HVDC tapping station: power tapping from a DC transmission line to a local AC network

The authors describe a new concept for tapping off a small amount of power from a high voltage direct current (HVDC) transmission line to a local network. The proposed new concept for a series tapping implies power conversion in two steps from the line to a local AC network. This will make it possible to the use a single phase transformer between the DC line potential and ground. The converter bridge connected in series in the DC transmission is of the current source line-commutated type, while the other two converters are of the voltage-source forced-commutated type. The basic functions of the converter are described and illustrated by the results from simulations with the EMTP program