Modeling of MVDC Multidrive Systems for Power Quality Analysis

In a medium voltage direct current (MVDC) multidrive system, several power electronics converters share a common MVDC bus. The contribution of this article relies on the systematic modeling approach of MVDC multidrive systems for the analysis of the MVDC bus power quality. Particularly, the interaction between the harmonics injected by the converters at the dc-link (due to the switching and modulation) with the natural resonances of the MVDC system (due to the line impedances and converters' bus capacitors) is the key point for the proposed power quality analyses. For that purpose, the analytical modeling of both, the MVDC bus system and the current harmonics injected at the dc-link by the MV converters (3L NPC topology) is addressed in this article. The signal power quality study can be conducted entirely in the frequency domain through the proposed modeling approach at a low computational cost. This article demonstrates the applicability of the methodology for a real case study based on a high-power medium-voltage 5.1-kV MVDC multidrive system.