B. Converter configurationlstation layout
The configuration of the HVDC main circuit has been
carefully analyzed,. For example, the pole configuration, with
two converter groups in series halves the power loss upon loss
of a converter group, and with adequate switchgear, ensures
that a group outage will not result in a pole outage.
Special attention has been devoted to the dc neutral. It is
normally regarded as one electrical point, and is electrically
common to both poles, but it is also a potential source for
bipolar trips. The neutral circuit configuration has to provide
separable neutrals, allow for maintenance, and, even more
important, it has to ensure faults can be detected and cleared
independently on each pole, even in normal operation, when
the neutral has no voltage.