A NOVEL TRANSFORMERLESS SHUNT COMPENSATION WITH MODULAR MULTILEVEL CONVERTER

Abstract

Nowadays, it is problematic to connect only one power semiconductor switch directly to the grid due to the
high voltage range. In order to solve this difficulty, a new type of power converter has been introduced as a
solution in high power applications. Multilevel Converters use high speed switching components, avoiding the
problem of linking them directly to the grid by connecting single devices among multiple DC levels. Different
Multilevel topologies have been developed in the last few years. The latest and most promising such topology
for high power applications is the Modular Multilevel Converter (MMC). The Modular Multilevel Converter
represents an emerging topology with a scalable technology making high voltage and power capability
possible. The MMC is built up by identical, but individually controllable sub modules. Therefore the converter
can act as a controllable voltage source, with a large number of available discrete voltage steps. This
characteristic complicates the modeling both mathematically and computational. A transformer less shunt
compensator (STATCOM) based on a modular multilevel converter introduces a new time-discrete appropriate
current control algorithm and a phase-shifted carrier modulation strategy for fast compensation of the reactive
power and harmonics, and also for the balancing of the three-phase source side currents. The performance of
the proposed STATCOM implemented using MATLAB/Simulink