AC and DC Fault Analysis in Hybrid Multi-Converter DC Grids

Investigation of complex multiterminal high-voltage direct current (MTDC) systems and dc grids combining multiple converters is critical for the future development of HVDC transmission systems. This paper studies the ac and dc fault-ride-through (FRT) capability in a hybrid multi-converter dc grid consisting of line-commutated converters (LCCs), modular multilevel converters (MMCs) and alternate arm converters (AACs). Simulation results for steady-state and transient operation based on a detailed equivalent model verify and validate the accuracy of parameter selection and fault handling capability of the hybrid multi-converter dc grid.