Modeling and Analysis of Resonance Interaction and Harmonic Transfer in Multi-bus DC Systems

With the rise of DC distribution technology, the issue of power quality in DC distribution networks has gradually attracted people's attention. The DC systems exhibit the characteristics of multi-bus cascading structures, with interaction and coupling between different buses occurring via power electronic converters, which can easily cause harmonic resonance and threaten the safe operation of the system. To investigate the characteristics of resonance interaction and harmonic transfer of multi-bus DC systems, this paper constructs a harmonic impedance model that considers the coupling effect of interlinking converters for multi-bus DC systems, based on which, the scope of harmonic resonance impacts is analyzed by examining both resonance excitability and observability. Moreover, the mechanism of harmonic resonance cross-level propagation in multi-bus DC systems is investigated based on the coupling transfer coefficient model of the interlinking converters. Finally, a simulation model of a multi-bus DC system is constructed to verify the correctness of the relevant theoretical analysis.