Research on Bidirectional DC/DC for DC Power Flow Controller

Abstract

In this paper, the principle of line power flow control in DC power grid is given first, and the influence of DC voltage and line equivalent resistance on DC power flow is analyzed based on this. Under the application background of flexible DC transmission system, a partial-power line power flow controller based on phase-shifted full-bridge topology is proposed. The proposed power flow controller has a single-stage structure, which can realize bidirectional control of DC line power without additional external power supply. The designed active clamp circuit can reduce the voltage stress caused by the leakage inductance of the transformer to the switches under reverse working conditions, and can realize the soft switching of all the switches on the secondary side through the clamp circuit. The soft- switching characteristics of the proposed topology in bidirectional operation are verified by simulation.