Impact of Switching Harmonics on Capacitor Cells Balancing in Phase-Shifted PWM Based Cascaded H-Bridge STATCOM
Journal article, 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

Author

Ehsan Behrouzian

Chalmers, Energy and Environment, Electric Power Engineering

Massimo Bongiorno

Chalmers, Energy and Environment, Electric Power Engineering

Remus Teodorescu

Chalmers, Energy and Environment, Electric Power Engineering

IEEE Transactions on Power Electronics

0885-8993 (ISSN)

Vol. 32 1 815-824

Areas of Advance

Energy

Subject Categories

Other Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1109/TPEL.2016.2535481

More information

Created

10/7/2017