Novel Modal Resonance Proximity Region between photovoltaic and multi-machine subsystems under inertia and damping variations

A Modal Resonance Proximity Region (MRPR) is proposed is to analyse dynamic interactions between photovoltaic (PV) converters and synchronous generators in a multi-machine system. The MRPR, delimited by the intersection of open-loop modes' possible positions from two subsystems, indicates that two open-loop modes would encounter each other in this region and modal resonances occur. Also, an indicator is utilised to assess the strength of such dynamic interaction. On top of MRPR and indicator, PV control parameters are optimised to avoid the possibly occurring modal resonances. As shown in time-domain simulation, the proposed MRPR can precisely capture the occurring region for potential modal resonances and such potential modal resonances can be significantly mitigated by the MRPR and indicator-based PV control parameter optimisation.