Impact of frequency modulation ratio on capacitor cells balancing in phase-shifted PWM based chain-link STATCOM
Paper in proceedings, 2014

The purpose of this paper is to investigate the impact of switching harmonics on the instantaneous power that flows in the cells of a chain-link based STATCOM when using Phase-Shifted PWM. Two different cases are investigated for the converter cells: low, and high switching frequency. It is shown that any deviation from the ideal conditions lead to undesired harmonics, which will impact the charge of the dc capacitors. It is also shown that for low switching frequencies, cells voltage sideband harmonics interact with baseband harmonics of the current and causes extra source of unbalance. In order to provide more uniform power distribution among the cells, two different methods called, a) carrier swapping and b) non-integer frequency modulation ratio are studied. In particular, it is shown that 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. Theoretical conclusions are validated through PSCAD simulation results.

Author

Ehsan Behrouzian

Chalmers, Energy and Environment, Electric Power Engineering

Massimo Bongiorno

Chalmers, Energy and Environment, Electric Power Engineering

Remus Teodorescu

Aalborg University

2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014

1931-1938

Areas of Advance

Energy

Subject Categories

Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1109/ECCE.2014.6953655

ISBN

978-147995698-2

More information

Latest update

4/18/2018