Decentral control of multi-terminal HVDC systems with automatic exchange of instantaneous and primary reserve power across AC grids

A control strategy for HVDC converters in future wide-area multi-terminal HVDC grids is developed. The control strategy is inspired by the dynamic behaviour of common motor-generator-sets used for electromechanical AC-DC conversion in the medium power range. With the new control strategy HVDC converters are on the one hand suitable for distributed control of DC voltage and they also contribute to the control and the stability of AC voltage and AC grid system frequency on the other hand. This ensures that a DC grid behaves like a network of conventional AC line interconnectors, that automatically transmits instantaneous- and primary reserve power if there is a disturbance in any of the connected AC nodes. The electric behaviour of one HVDC converter with the new control strategy is studied in simulation.