Abstract
This paper presents an experimental performance
evaluation of different control strategies for providing virtual
inertia from power electronic converters. The evaluation is based
on a laboratory-scale prototype of a point-to-point HVDC
transmission system with Modular Multilevel Converters
(MMCs). Operation with a grid emulator connected to a realtime
simulator reproduces the behavior of a power system and
allows Power-Hardware-in-the-Loop (P-HiL) experiments.
Control of the inverter terminal for providing virtual inertia to
the simulated power system is evaluated with four different
control system implementations. The four cases include a
conventional control system enhanced with df/dt-based inertia
emulation functionality and three different Virtual Synchronous
Machine (VSM) implementations based on emulation of a
synchronous machine swing equation. The dynamic response in
the power flow and the frequency transients are evaluated for all
cases, and the inertial energy exchanged with the isolated power
system is assessed in comparison to a conventional power
controller without inertia emulation. The results demonstrate
that all the evaluated implementations can provide similar
inertial response when operated in a small isolated grid, while
clear differences in dynamic response and stability properties are
revealed during operation under strong grid conditions.
evaluation of different control strategies for providing virtual
inertia from power electronic converters. The evaluation is based
on a laboratory-scale prototype of a point-to-point HVDC
transmission system with Modular Multilevel Converters
(MMCs). Operation with a grid emulator connected to a realtime
simulator reproduces the behavior of a power system and
allows Power-Hardware-in-the-Loop (P-HiL) experiments.
Control of the inverter terminal for providing virtual inertia to
the simulated power system is evaluated with four different
control system implementations. The four cases include a
conventional control system enhanced with df/dt-based inertia
emulation functionality and three different Virtual Synchronous
Machine (VSM) implementations based on emulation of a
synchronous machine swing equation. The dynamic response in
the power flow and the frequency transients are evaluated for all
cases, and the inertial energy exchanged with the isolated power
system is assessed in comparison to a conventional power
controller without inertia emulation. The results demonstrate
that all the evaluated implementations can provide similar
inertial response when operated in a small isolated grid, while
clear differences in dynamic response and stability properties are
revealed during operation under strong grid conditions.