Impact of Switching Harmonics on Capacitor Cells Balancing in Phase-Shifted PWM Based Cascaded H-Bridge STATCOM
Artikel i vetenskaplig tidskrift, 2016

The purpose of this paper is to investigate the impact of switching harmonics on the instantaneous power distribution in the cells of a cascaded H-Bridge based STATCOM when using Phase-Shifted PWM. The case of high and low switching frequency for the converter cells are investigated and the interaction between voltage and current harmonics is analyzed. It is shown that in both cases, this interaction results in an uneven power distribution among the cells in the same phase leg, leading to drifting of the dc-capacitor voltages and thereby the need for proper stabilization control loops. It is also shown that the selected frequency modulation ratio affects the active power distribution among the cells. In particular, the selection of a non-integer frequency modulation ratio helps in providing a more uniform power distribution among cells of the same phase leg, thus contributing to the capacitors balancing. A methodology for optimal selection of the frequency modulation ratio is given. Theoretical conclusions are validated through simulation and experimental results.

Pulse width modulation

Static VAR compensators

Cascade systems

Reactive power control

Multilevel systems

Harmonic analysis


Ehsan Behrouzian

Chalmers, Energi och miljö, Elkraftteknik

Massimo Bongiorno

Chalmers, Energi och miljö, Elkraftteknik

Remus Teodorescu

Chalmers, Energi och miljö, Elkraftteknik

IEEE Transactions on Power Electronics

0885-8993 (ISSN)

Vol. 32 1 815-824 7422150




Annan elektroteknik och elektronik



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