In order to solve the impact of photovoltaic volatility on power systems, flexible HVDC transmission technology is more and more used for photovoltaic grid connection. As the most important component of flexible HVDC transmission systems, the characteristics of the equipment in the flexible HVDC converter station are of great significance to the safe and stable operation of the HVDC transmission system. When the AC/DC side of the converter station fails or is struck by lightning, the converter station equipment will have an overvoltage. In severe cases, it will damage the equipment in the converter station and threaten the safe and stable operation of the system. Therefore, this paper comprehensively considers the various overvoltage conditions of a ±30kV converter station with modular multilevel converter (MMC), and uses PSCAD/EMTDC for simulation calculation. According to the calculation results, the arrester configuration of the converter station is analysed, and the results can be used for equipment selection and engineering design.