DC link capacity enhancement for dynamic operation of back-to-back modular multilevel converters

MSc thesis of Robin van der Sande

This research project explores the opportunity of operating an MMC-based MVDC
distribution link at a DC link voltage higher than the rated value. This is achieved while
operating with the same submodule stresses and preserving the AC-side harmonic
performance. The voltage enhancement is performed to improve the power transfer
capacity of an MVDC link, which can help to avoid grid congestions. Alternatively, the
enhancement can improve the efficiency of the DC link system for a given operating power.
Furthermore, a dynamic control system is proposed and verified, which can implement the
DC link voltage enhancement for both steady-state and dynamic conditions.