With the development of power electronics technology and the continuous advancement of renewable energy integration technologies, supportive policies have propelled the rapid growth of the wind power industry. Series capacitor compensation technology reduces line losses, increases transmission capacity, and enhances system stability. It is a mature and cost-effective solution for long-distance power transmission and has become a primary measure for delivering large-scale wind farm power to the grid.

Since the Gezhouba–Nanqiao Project, the number of HVDC transmission lines, converter stations, and transmission distances in China’s highvoltage direct current (HVDC) power transmission systems have increased sharply. Accordingly, the overvoltage fault rate in AC/DC transmission systems has also risen. Especially in regions such as Hubei Province, Shanghai, and Guangdong Province, which host multiple HVDC systems, the complexity of the AC/DC grid results in more intricate faultcausing factors. However, the simulation of largescale AC/DC grids has mainly been applied to the development and verification of control strategies and power flow analysis. During modeling, extensive equivalent processing is often adopted, with many primary equipment simplified or even omitted, making it impossible to obtain actual overvoltage conditions on the equipment.

With the development and commissioning of hydropower in western Yunnan Province, the main power transmission grid for the west-to-east power transmission in the Southern Power Grid during the 12th Five-Year Plan period will form a configuration of eight AC and eight DC lines. The transmission distance between the eastern and western AC grids is increasing, and the grid structure with hybrid AC/DC operation is becoming more complex. Implementing asynchronous grid interconnection between Yunnan Grid and the Southern Power Grid can effectively mitigate grid security and stability issues caused by AC/DC power transfer, thereby improving power supply reliability.