DC power flow controller(DCPFC)can improve the controllability of line power flow. This paper presents an optimal locating and ratio calculating method of voltage-type DCPFC in the DC grid operating under the multi-point voltage droop control strategy. A mathematical model of DC grid including DCPFC is developed. The sensitivity analysis method is used to study the influences of the controller on the power flow distribution in DC grid. And the best placement of the controller is obtained from the perspective of the whole DC grid. In view of the inability of power flow entropy to highlight the overload situation

an improved weighted power flow entropy of the DC grid is proposed. Meanwhile

by setting the improved weighted power flow entropy as the objective to optimize the system power flow

the transformer ratio of the DCPFC can be obtained. An offshore six-terminal DC grid model has been used to validate the effectiveness of the proposed method.