Optimal Energy-based Valve Current Reference Generator for MMC VSC-HVDC

In this work, a new energy-based valve current reference generator algorithm is introduced. The proposed method obtains the converter valve current references in the abc coordinate system with the aim to meet the ac and dc power demands while controlling the energy stored in the converter around a desired target value. The advantage of this approach relies on the configurable optimality of the solution. Moreover, the proposed approach does not require the phase angle information for a given ac current demand. In addition to this, the proposed approach outperforms other conventional current and energy control methods in terms of a weighted combination of conduction losses and valves energy deviation from a prescribed target. The method has been validated by simulation results under both steady-state and fault conditions.