  We propose a localized protection scheme based on modal analysis in
multi-terminal modular multilevel converter (MMC) based high voltage DC (HVDC)
systems. The paper addresses the issues of localized protection scheme based DC
fault identification, such as differentiating between external and internal
faults, classification of type of fault contingency i.e., pole to pole
(\textit{PTP}) or pole to ground (\textit{PTG}) for high impedance faults
(HIFs) in the system. The scheme works on equivalent network of multi-terminal
MMC-HVDC system for a DC fault, using phase-modal transformation to analyse
line-mode and zero-mode voltage across the current limiting reactor (CLR) for
different possible contingencies in the presence of fault resistance. The
protection scheme is validated to be reliable for HIFs and in the presence of
White Gaussian Noise (WGN) in measurement. The scheme operation is validated to
be intact for varying fault location, fault resistances and system transients.
