Sequence-Decoupled Resonant Control of Three-Phase Grid-Interfacing Inverter for Local Voltage Support Under Unbalanced Load

This paper considers a three-phase four-wire grid-interfacing voltage-source inverter with local unbalanced and distorting loads. A sequence-decoupled resonant control strategy is proposed to support the local voltage on top of conventional active power regulation. The local voltage at the point of common connection, which is traditionally used for grid synchronization for distributed generators, is also used for sensing unbalanced and harmonic voltages. Therefore, measurements of load currents for unbalanced and harmonic compensation can be eliminated with the proposed approach.