Most of the existing DC power flow controllers have two ports and can only execute auxiliary control for the power flow of one line. For comprehensive control of power flow distribution in the DC power grid

this paper proposes a multi-port DC power flow controller(M-DCPFC)for the flexible DC power grid

which is able to control the power flow of many lines at the same time and easy to expand. Firstly

on the basis of sufficient research on the existing DC power flow controller

the topological structure of the M-DCPFC is proposed

while its working principle is described. Secondly

the equivalent circuit of M-DCPFC is studied

then the control strategy for its stable operation design is developed. Finally

the proposed topological structure and the control strategy are verified by the Zhoushan five-port flexible high voltage direct current(HVDC)system installed with a three-port DC power flow controller in the RT-LAB simulation platform.