Analysis of typical fault characteristics of modular multilevel converter for flexible HVDC transmission

Modular multilevel converter (MMC) has been widely used in VSC-HVDC system for its smooth output waveform, low harmonic content and switching loss. But compared with the conventional LCC-HVDC system, modular a short development history, few engineering applications, high failure rate lacks of very effective protection strategies, which limits further development. Therefore, this paper firstly introduces topological structure MMC working principle. Then commonly control policy dual-terminal MMC-HVDC project is elaborated. Finally, transient electrical characteristics typical faults are detailedly analyzed through combination theoretical analysis simulation, such as three phase circuit valve, single grounding bridge arm circuit. The conclusion provides an essential theory research strategy project.