Abstract
This paper presents a technique for damping of
oscillations in ac grids by control of VSC-HVDC links. The
effect of the proposed controller is equivalent to a mechanical
friction between two asynchronous networks (modelled as rotating
masses) interconnected by the HVDC link. Therefore, the
dynamics of the ac grids will be coupled, and the virtual friction
gain can be utilised to effectively damp frequency oscillations
in any of the ac networks. A centralised and a decentralised
implementation of the proposed controller are presented. It is
shown that both implementations of the virtual friction-based
damping can effectively attenuate poorly damped frequency
oscillations in both of the interconnected ac grids and that
the decentralised implementation can ensure damping without
relying on fast communication between the HVDC terminals.
The impact of the proposed controller on the stability of the
two grids is analysed with a simplified system model, and the
performance is experimentally validated by a scaled laboratory
setup.
oscillations in ac grids by control of VSC-HVDC links. The
effect of the proposed controller is equivalent to a mechanical
friction between two asynchronous networks (modelled as rotating
masses) interconnected by the HVDC link. Therefore, the
dynamics of the ac grids will be coupled, and the virtual friction
gain can be utilised to effectively damp frequency oscillations
in any of the ac networks. A centralised and a decentralised
implementation of the proposed controller are presented. It is
shown that both implementations of the virtual friction-based
damping can effectively attenuate poorly damped frequency
oscillations in both of the interconnected ac grids and that
the decentralised implementation can ensure damping without
relying on fast communication between the HVDC terminals.
The impact of the proposed controller on the stability of the
two grids is analysed with a simplified system model, and the
performance is experimentally validated by a scaled laboratory
setup.