Technical Exploration of New High Voltage DC Converter

High Voltage Direct Current(HVDC) transmission technology can not only transmit electricity over a long distance, but also help to realize the interconnection of asynchronous power grids and promote the development of power industry. Modular multi-level converters are widely used in HVDC and distribution systems due to their advantages of easy cascade, easy commutation and low harmonics. Firstly, the working principle of Modular Multilevel Converter (MMC) was introduced, and then the shortcomings of full-bridge module and clamp-type double-level module aiming at the self-cleaning measures of DC side faults were analyzed. To obtain the ability of DC fault clearance, a kind of new type MMC was designed with adopting Reverse Blocking Insulated Gate Bipolar Transistor(RB-IGBT), and the above simulation results are then given. By designing a half-bridge module with RB-IGBT, the use of power electronic components is reduced, and the self-cleaning of DC side faults can be realized effectively. Reverse Blocking Half Bridge Sub-Modules (RB-HBSM) is installed at both ends of the arm. When the fault occurs on the DC side, the RB-HBSM is blocked. When the fault is eliminated, the DC voltage can be quickly restored by unlocking the sub-module.