A New Multilevel Converter Configuration with Reduced Component Count for Medium Voltage STATCOM Application

Abstract

This paper introduces a new Multilevel STATCOM for Medium Voltage (MV) applications which has low component count compared to other multilevel configurations. The converter consists of a three phase bridge circuit, bidiectional switches and wave-shapers. The wave-shaper consists of series connection of half-bridge submodules, and provides necessary wave shape, so that the converter generated voltage approaches near to sinusoid. As a result, passive filter is not required which reduces the foot-print and minimizes magnetic interference. A Part of the circuit is operated at fundamental frequency and hence reduces the losses in the converter and increases efficiency. The converter is configured in such a way that only two arms of the wave-shaper is sufficient to make three phase circuit which minimizes component count to a large extent. As an example, only 52 switches are required for the proposed converter whereas the switch count is 120 for Cascaded H-bridge Converter (CHB) considering similar voltage levels (say 21). The control methods are developed for the proposed converter including balanced and unbalanced operations. The performance of the converter is checked through PSCAD simulation and the results show satisfactory performance.