This paper first proposes the topology of multi-port DC substation

and creates its mathematical model. The substation can not only achieve the interconnections of different types of offshore wind farms and HVDC systems with multi-voltage levels

but also can implement a centralized DC power flow regulation. Then the multi-port DC substation is applied to offshore wind farm integration with multi-voltage levels

and its master-slave control strategy is proposed. The strategy takes advantage of each port of the DC substations to achieve the stable operation during wind power fluctuation or any port of the substation fault. Finally

a simulation model of a multi-terminal DC test system is established in the PSCAD/EMTDC simulation platform. Steady-state simulation analysis and fault simulation are performed to validate the proposed strategy

the results show that the strategy can ensure the stable and reliable operation of the multi-port DC substation. The work is supported by National High Technology Research and Development Program of China (863 Program) (No. 2012AA050208) and Program of Introducing Talents of Discipline to Universities (“111” Program) (No. B08013).