Abstract：The characteristics of the DC side of the DC distribution network are multi bus cascades，multiple

converters，and strong coupling of the buses，which can easily cause harmonic resonance and threaten the safe

operation of system equipment.Aims at the problem of unclear resonance interaction and harmonic transmission

mechanism between DC busbars，firstly，a harmonic impedance model of a multi-bus DC system was constructed，

in which the coupling effect of isolated and non-isolated interlinking converters has been taken into account. Based

on this model，the distribution and influence range of harmonic resonance in the multi-bus DC system were studied

from the perspectives of resonance excitability and observability. Then，based on the coupling transfer coefficient

model of the intermediate converter，the influence mechanism and law of the interlinking converter on the resonant

interaction between the two DC busbars were explored，and a method of optimizing the parameters of the

interlinking converter to suppress the resonant interaction between the busbars was proposed. Finally，a simulation

model of a multi-bus DC system was constructed to verify the correctness of the theoretical analysis and the

effectiveness of the proposed optimization approach for interlinking converter parameters.

      Key words：DC；power quality；harmonic resonance；interaction；intermediate converter