| Abstract |
This paper compares three topologies (Partially Rated Stack - PRS, Stack Parallel Branch - SPB, Induc-tor Parallel Branch - IPB) which integrate energy storage solutions for HVDC-scale modular multilevelconverters to provide ancillary services such as frequency support. The comparison looks (i) at the extra power capability from their energy storage under maximum current and voltage limits of the converter and (ii) the extra penalties in terms of losses and components that these topologies require on top of a conventional MMC. Results indicate that PRS has the most consistent power capability across the power range but comes with higher losses and more extra components, while the SPB and IPB have each trade-offs between power capability, flexibility and efficiency. |
