Modular Multilevel DC-DC Converter Configuration for Bipolar HVDC Links

A Modular Multilevel DC-DC converter topology is proposed in this paper which can interface a bipolar-Line Commutated Converter (LCC) based High Voltage DC (HVDC) link with a bipolar-Voltage Source Converter (VSC) based HVDC link. The topology ensures stable operation in the event of failure of one of the poles of the LCC based HVDC link, thus maintaining half the power flow in both the directions. The operating principle of the converter and the controllers are described briefly in this paper with suitable block diagrams. All necessary simulations are performed on MATLAB/Simulink platform to validate stable performance of this converter.