Research on a Fault Ride Through Strategy for New Energy Grid Connection through Flexible Direct Current Transmission

The large-scale integration of wind power, photovoltaic and other new energy through flexible and direct grid connection is an important measure to achieve the dual carbon goal. In order to achieve the safety and reliability of the new energy flexible direct transmission system, it should have the ability to pass through faults in the AC power grid. This article proposes a fault traversal control method based on fault current limiting for a new energy grid connected system through flexible direct transmission. Firstly, an overview of the demonstration project of new energy through flexible and direct grid connection is introduced, and control strategies for constant voltage control, VF droop control, and DC/DC control are designed. Secondly, a complete fault traversal control strategy was designed in detail, including voltage droop controller, frequency droop controller, current limiting controller, and voltage and current command selection. Then, a new energy grid connected demonstration project model was built on the PSCAD/EMTDC simulation platform, and fault traversal strategy simulation research was conducted the converter stations VSC2. Finally, validation experiments of this strategy were conducted on the demonstration project site. The simulation and on-site test results show that after a single-phase grounding fault occurs, the station control and valve control protection do not act. After the fault is cleared, it returns to normal operating state.