Coordinated control design of the voltage and current loop of a current flow controller for meshed HVDC grids

This paper is focused in the control design of a DC/DC Current Flow Controller (CFC) for meshed HVDC grids. It proposes a control design methodology based on an outer current loop to regulate DC grid currents and an inner voltage loop to keep under control the CFC voltage. This approach is able to limit the CFC voltage to avoid exceeding the device limitations. A linear model of the HVDC grid including the CFC is obtained to apply linear control techniques to design the regulator. The system performance is validated by means of simulations considering different case studies