Offshore wind power is presently one of the most promising renewable energy fields

while

the VSC DC transmission is the main DC transmission mode of distant ocean offshore wind power. With the development of economy and society

the transmission capacity of submarine cables with lower voltage class has been difficult to meet the growing demand for distant ocean offshore wind power transmission. In the whole offshore wind power VSC DC transmission system

DC submarine cable is a very important component and its safety is directly related to safe and reliable operation of the entire DC transmission project. Therefore

it is particularly important to perform a comprehensive and detailed study on the overvoltage characteristics of submarine cables. In order to facilitate the analysis of overvoltage characteristics of DC submarine cables

based on a ±525 kV offshore wind power VSC DC transmission project

a simulation model of two terminal VSC DC transmission (MMC-HVDC) based on modular multilevel converter is set up under PSCAD/EMTDC environment. With DC submarine cables as the research object

overvoltage under various fault conditions are studied by using this model. Finally

the insulation level and voltage- time envelope of the DC submarine cable

including the slow wave front overvoltage level with different wave front times and reverse polarity overvoltage level

are given. The research results has provided a reference for the selection

test and design of the VSC DC submarine cable.