In low-voltage grid applications with increasing decentralized sources, it is necessary to provide the technical facilities to sustain power quality and subsequently grid stability on-site. Therefore, it is reasonable to assign these tasks in particular grid sectors to the also increasing quantity of power converters.
This paper presents a novel control strategy for injecting positive and negative sequence currents into the grid to compensate unbalanced voltage level situations. The proposed control scheme allows to control each converter phase stand-alone. Kalman Filters are used to provide estimated current values in a rotating reference frame for each phase. The performance of the ﬁlter process in a closed control loop is demonstrated with a laboratory converter.