Operation and performance of a medium-voltage DC link

The operation of a voltage source converter (VSC)-based medium-voltage (MV) direct current (DC) link is described. The use of a DC link in an MV distribution network is presented, considering salient similarities and differences to a high-voltage DC link. A PSCAD/EMTDC model was used to demonstrate the dynamic operation of an MVDC link, under normal and faulted network conditions. The study shows that MVDC can provide flexibility in a distribution network by decoupling real (P) and reactive (Q) power flows through the link, under normal operation. During a fault, however, the current injected from the converter could interfere with the detection and discrimination of AC system faults, in distribution networks with current-based protection scheme