A hybrid modular interline current flow controller for meshed HVDC grids

In meshed high voltage direct current (HVDC) grid, the current flows through the lines cannot be controlled with sufficient freedom without additional power electronics based devices, namely current flow controller (CFC). In this paper, a novel hybrid modular interline CFC is proposed based on H-bridge sub-modules (SMs) and thyristor valves. Due to its modularity, the proposed CFC is particularly suitable for applications requiring high voltage and large power capacity. The circuit structure, operation principle and parameter design are presented. In addition, a control strategy is developed for the proposed CFC. Simulations are carried out using a four-terminal meshed HVDC grid to verify the effectiveness of the topology and its control strategy. A downscaled prototype is built which further validates the proposed CFC