A Novel Control Approach to Multi-Terminal Power Flow Controller for Next-Generation DC Power Network

This paper studies a novel control approach to multi-terminal power flow controller (MTPFC) for next-generation DC power network. We have proposed and validated bidirectional power flow controller (BPFC) and MTPFC as promising power flow controllers for next-generation DC power networks. In BPFC, total power imbalance possibly causes voltage fluctuation of the inter-stage link capacitor. The fluctuation affects performance of the power flow control. Then, in MTPFC, a compensation node that keeps the inter-stage link capacitor voltage at a predetermined constant value, plays an important role for precise operation of MTPFC. However, the introduction of the compensation node needs additional costs. In this paper, we propose a novel control approach that properly controls power flows even in case that there are fluctuations of the voltage of the inter-stage link capacitor. The control approach is realized by using measured values of the voltages for the control system. The proposed approach is validated by experimental results.