| Abstract |
This paper presents a comparison between two DC-voltage balancing strategies for cascaded star-connectedmultilevel STATCOM: zero-sequence voltage, and negative-sequence current control. Different levelsof unbalance and grid strengths are considered. The impact of the control strategies on the convertratings in terms of voltage and current requirements are compared and the operating range of the converterusing each control strategy is theoretically derived. The results show that for a given systemratings, the operating range of the converter using negative-sequence current control is wider than thezero-sequence voltage control when the STATCOM is connected to weak grids. On the contrary, incase of connection to strong grids the zero-sequence voltage control can provide wider operating range.PSCAD simulation results are provided to prove the theoretical results. |
