A multiport embedded DC power flow controller for ISOP-DCT

Abstract

The DC transformers (DCTs) can achieve flexible power flow control in the ring-type and meshed-type multi-terminal DC grids with less loss. However, due to the limited power flow control range of the DCTs, the power flow controller (PFC) is expected to boost the system's controllability. Unlike the conventional DCTs, this paper proposes an embedded DC power flow controller (e-DCPFC) formed by a PFC and an input-series-output-parallel (ISOP) DCT. This device has the features of multiple ports and extended bidirectional power flow control capability. The operational principle of the e-DCPFC is analysed in detail. And a modified input voltage sharing (m-IVS) control strategy is proposed in this paper. This control scheme not only maintains the input capacitor voltage balanced of the ISOP structure but also controls the power of the extra ports provided by the e-DCPFC. The feasibility and effectiveness of the proposed topology and control strategy are verified via MATLAB simulation mode.