Abstract
Fast and accurate fault direction criteria is crucial for efficient
protection in hybrid multi-terminal HVDC transmission systems. The
current variation method is commonly used to identify fault direction
but is affected by fault resistance and distributed capacitance. This
paper proposes a new direction criterion based on the backward fault
traveling-wave, which has stronger resistance to interference from
transition resistance and operates at a faster speed than other methods.
Additionally, this paper provides the time-domain expression of the
traveling wave after multiple reflections between the fault point and
the converter station port, enabling the calculation of the threshold
setting for the criterion. The new direction criterion is tested in
PSCAD/EMTDC, and simulation results demonstrate that it can accurately
identify fault direction and has a strong ability to withstand
transition resistance.