Abstract
Future multi-terminal HVDC (MTDC) grids
will be based on Voltage Source Converter (VSC)
technology. However, existing and planned VSC HVDC
connections for offshore wind farms and cross-border
interconnections are mainly point-to-point links which
are operated at different voltages and can have different
grounding schemes. Thus, DC/DC converters will become
necessary for interconnection of independent HVDC
transmission schemes into future meshed MTDC grids.
This paper starts with a brief review of topologies for
DC/DC converters in HVDC applications with particular
attention directed towards interconnection of HVDC
systems with different grounding schemes. The control
and operation of a front-to-front transformer-coupled
AC/DC/AC solution is analyzed as an example of a
topology that will be suitable when galvanic separation is
required. The investigated topology is demonstrated by
time-domain simulations in Matlab/Simulink when
interconnecting a monopolar HVDC link with a meshed
bipolar MTDC configuration defined in the Cigré DC
grid test system.
will be based on Voltage Source Converter (VSC)
technology. However, existing and planned VSC HVDC
connections for offshore wind farms and cross-border
interconnections are mainly point-to-point links which
are operated at different voltages and can have different
grounding schemes. Thus, DC/DC converters will become
necessary for interconnection of independent HVDC
transmission schemes into future meshed MTDC grids.
This paper starts with a brief review of topologies for
DC/DC converters in HVDC applications with particular
attention directed towards interconnection of HVDC
systems with different grounding schemes. The control
and operation of a front-to-front transformer-coupled
AC/DC/AC solution is analyzed as an example of a
topology that will be suitable when galvanic separation is
required. The investigated topology is demonstrated by
time-domain simulations in Matlab/Simulink when
interconnecting a monopolar HVDC link with a meshed
bipolar MTDC configuration defined in the Cigré DC
grid test system.