Investigation of Negative-Sequence Injection Capability of Cascaded H-Bridge Converters in Star and Delta Configuration
Artikel i vetenskaplig tidskrift, 2016

The aim of this paper is to investigate the ability of cascaded H-bridge STATCOMs in star and delta configuration to exchange negative-sequence current with the connecting grid. Zero-sequence voltage for the star and zero-sequence current for the delta configuration are utilized to guarantee DC-capacitor voltage balancing. A general solution for the required zerosequence voltage/current for any kind of unbalanced condition is provided. The obtained solutions show that a singularity for both configurations exists under specific conditions, leading to infinite zero-sequence requirement. In case of star configuration, this singularity occurs when the amplitude of the positiveand negative-sequence components of the current output of the converter are equal. Analogously, the singularity for the delta configuration occurs when the amplitude of the positive- and negative-sequence components of the voltage at the converter terminals are equal. This singularity impacts the ratings of the system and imposes a limitation in the utilization of the compensator for unbalance compensation purposes, both in industrial and utility applications. Experimental results are presented to validate the theoretical analysis.


Cascaded multilevel converter

unbalanced conditions

DC-voltage balancing



Ehsan Behrouzian

Chalmers, Energi och miljö, Elkraftteknik

Massimo Bongiorno

Chalmers, Energi och miljö, Elkraftteknik

IEEE Transactions on Power Electronics

0885-8993 (ISSN)

Vol. 32 1675-1683




Annan elektroteknik och elektronik