MMC New Type Sub Module Toplogy and Control

High-voltage direct current transmission technology based on modular multi-level converter (MMC-HVDC) has been widely used in power grid applications presently, and plays an important role in enhancing the power grid stability and improving the intelligence and controllability of the power grid. Dc line fault suppression is still an unavoidable problem, based on the review of dc line fault current suppression technologies, the paper studies a new sub-module topology composed of clamp circuits to realize the arm capacitor bidirectional current cascade charging after system blocking, and achieve dc fault suppression. At the same time, the voltage output characteristics of the new topology are analyzed, and its voltage balance control strategy and non-blocking dc fault suppression strategy are also studied. Finally, the two-end simulation model is built in PSCAD/EMTDC, and the new sub module dc fault suppression characteristics are simulated and verified.