Multiport Interline Current Flow Controller for Meshed HVDC Grids

Abstract

In meshed high voltage direct current grids, the current of each line cannot be controlled independently, since it depends on the resistances between nodes. Additional devices, such as current flow controllers (CFCs), may be needed to avoid bottlenecks or line overloads. This work presents a multiport dc-dc-based CFC topology to be connected to n lines with unidirectional current flows. The device is able to control the dc lines' currents to the desired value by inserting variable voltage sources in series. First, the modeling of the generic n-port topology is presented and then, its modulation and control strategy are described. In the first case study, the concept is validated considering a 5-port CFC by means of dynamic simulations using different control methods. Finally, in the second case study, a 3-port CFC prototype is built and tested in an experimental platform in the laboratory considering different control modes.