Mode Switching Control in the MMC-HVDC

With the continuous promotion of national energy strategy, offshore wind power has become an important direction for clean energy development due to its mature technology and scale potential. In long-distance transmission, flexible DC transmission technology (HVDC) based on modular multilevel converter (MMC) has become the mainstream solution. Core control strategies are grid-following (easy grid connection but unstable in weak grids) and grid-forming (provides grid support but has slow dynamics and oscillation risks). In view of the demand for grid stability under the scenario of high proportion of new energy access, this paper proposes a smooth switching strategy based on integrator pre-synchronization, so that the system can autonomously switch between the two types of modes according to the working conditions. Through the Matlab/Simulink simulation verification, the program can effectively inhibit the switching impact and oscillation, providing technical support for the flexible regulation of offshore wind power grid-connected system.