Abstract:
DC-integrated wind farm provides a feasible solution for new energy transmission in the "Shagoe Wilderness". However, its core equipment, DC converter, needs to break through the technical bottlenecks of low power and limited voltage. In order to overcome the above problems and achieve the interconnection of pseudo-bipolar DC pooling system and true bipolar DC sending system, a bipolar DC converter with short-circuit current limiting capability is proposed. Firstly, the topological operation principle and parameter design method of the proposed converter are analyzed, the matching control and modulation methods are proposed, and then the fault current blocking process of this converter is investigated. Finally, the feasibility of the topology and control strategy of the proposed reverse-resistance self-levelling modular multilevel dc-dc converter is verified by building a model with MATLAB/Simulink software. The results show that the proposed bipolar DC converter is able to match the difference in the operating modes between the two ends of the pseudo-bipolar wind farm and the true bipolar transmission line, and can quickly block the fault current.