Fast compensation of DC bus voltage drops using modular multilevel converters

Abstract

For a DC grid using modular multi-level converters (MMCs) fast control of the DC bus is an important requirement. A control design is presented where a sudden DC voltage drop is compensated without any influence on the AC side. Using a suitable pattern in the MMC internal circular currents, the DC current can be adjusted and the MMC can be brought to a new steady state with symmetrised arm energies within few milliseconds.

Keywords

• power grids
• power convertors
• HVDC power convertors
• power control
• voltage control
• modular MMCs
• DC grid
• modular multilevel converters
• fast control
• important requirement
• control design
• sudden DC voltage drop
• suitable pattern
• MMC internal circular currents
• DC current
• fast compensation
• DC bus voltage