In this paper

a kind of mixed dual feed-in DC transmission system is proposed because of aggregation of high load area in China

reverse distribution of power and main transmission of wind power consumption and as for large number of wind abandon circumstance and large construction HVDC transmission grid. This system is based on wind and thermal interconnection DC transmission

to add wind power island through VSC DC transmission system. The comparison among short circuit capacity ratio

the maximum DC transmission power index and traditional dual feed-in system is proposed and the simulation model is set up in DIg SILENT software and the superiority of the mixed dual feed-in is shown by the result. Finally

the transient characteristics of dual and traditional feed-in based on fault disturbance method is compared and analyzed. The simulation results show that the mixed dual feed-in system can increase transmission power of wind farm

the VSC system can regulate effectively AC busbar voltage at power grid side during the fault and increase transmission power of LCC DC channel.