It means that the wind turbine grid connection can be understood as two parts, and both parts are synchronized.
The first step is for the wind turbine generator set to meet the startup requirements, start the machine to output electric energy, and connect it to the 3.5KV power grid inside the wind farm.
The second step is to merge into the national Grid. Wind farms are generally equipped with booster stations, and the output power is converted from 3.5KV to 110KV (or 220KV) and fed into the national grid.