Power Quality Improvement Using Cascaded Multilevel Statcom with Dc Voltage Control

The “multilevel converter” has drawn tremendous interest in the power industry. The general structure of the multilevel converter is to synthesize a sinusoidal voltage from several levels of voltages, Multilevel voltage source converters are emerging as a new breed of power converter options for high power applications, These converter topologies can generate high-quality voltage waveforms with power semiconductor switches operating at a frequency near the fundamental. Among the available multilevel converter topologies, the cascaded multilevel converter constitutes a promising alternative, providing a modular design that can be extended to allow a transformer less connection. A new control strategy is proposed in this paper with focus on dc voltage regulation. Clustered balancing control is realized by injecting a zerosequence current to the delta-loop, while individual voltage control is achieved by adjusting the fundamental content of ac quasi-square-waveform voltage of high-voltage converter.