Effective and Simple Control of Grid-Connected Three-Phase Converter Operating at a Strongly Distorted Voltage

Three-phase power electronics converters (PECs) are commonly used as an interconnection of DC loads/sources with the electrical AC power system. Their important goal is to ensure three-phase symmetrical and pure sinusoidal grid current waveforms. Unfortunately, frequent adverse of grid voltage conditions like the occurrence of higher order harmonics and dips/sags leads to problems in maintaining high-quality parameters of current and stable operation of PEC. Therefore, a more complex control algorithms are usually used to solve those problems. In this paper, effective and simple control is proposed to mitigate grid current distortions caused by grid-voltage harmonics. This improvement of current quality can be easily obtained in control of grid-connected PEC using only band notch filtered grid voltage as a feedforward without any additional control loops parallel connected to linear current controllers (tuned to fundamental frequency). Theoretical analysis with simulation and experimental investigations are presented, which prove very good properties and advantages of the proposed control idea.