Topologies for VSC transmission

The increasing rating and improved performance of self-commutated semiconductor devices have made DC power transmission based on voltage-sourced converters possible. This technology is called VSC transmission. The main components in a DC scheme are depicted and their functions explained. The features of three main categories of converter topology suitable for DC transmission are described. Three specific converters, namely two-level, three-level diode-clamped and four-level floating-capacitor converters for a 300 MW scheme, are compared in terms Of costs, DC capacitor volume, commutation inductance and footprint. The floating capacitor converter is shown to yield the lowest system cost.