Contents 1. Introduction
In recent years, multilevel inverters have drawn tremendous interest in the field of high-voltage and high-power applications such as the static synchronous compensator (ST ATCOM) applications. Referring to the literature reviews in [3] [4], the cascaded multilevel converter (CMC) with separated DC capacitors is clearly the most feasible topology for use as a power converter in STATCOM applications and there are many advantages described in [4]. The cascaded converter topology not only simplifies hardware manufacturability, but also makes the entire system flexible in terms of power capability. However, those challenges researchers how to improve its dynamic responses and balance its DC buses due to excessive amount of capacitors. Up to date, several literatures have discussed configuration and control strategy of the cascaded multilevel STATCOM. Such control theme and dynamic properties are studied, and also the capacitor voltage balance control theme is proposed in [3] [6] [9]. The system model and another control theme are proposed in [2]. A simple formula is proposed to calculate the required capacitance of the capacitor in DC link of each single H-bridge inverter in [4]. Another novel control themes to reduce the EMI are proposed in [5] [7] [8] [9].
