Virtual Synchronous Machine Control of VSC HVDC for Power System Oscillation Damping

Two different methods for implementing inertial
damping on a Virtual Synchronous Machine (VSM) and their
potential for attenuating power system oscillations when utilized
in a VSC HVDC terminal are investigated in this paper. As a
reference case, the VSM is considered with only a frequency
droop providing damping in the virtual swing equation. Then,
the effect of damping based on high-pass filtering of the virtual
speed is compared to damping based on high-pass filtering of the
measured grid frequency. A simplified model of a power system
with two equivalent generators and a VSC HVDC terminal
is introduced as a case study. Analysis of the small-signal
dynamics indicates that damping based on the VSM speed has
limited influence on the power system oscillations, while improved
attenuation can be obtained by introducing damping based on
the locally measured grid frequency. The presented analysis and
the operation of the proposed VSM-based damping strategy is
validated by numerical simulation of a 150 MVA VSM controlled
VSC HVDC terminal connected to a dynamic model of the
assumed grid configuration.