Investigation of multilevel multifunctional grid connected inverter topologies and control strategies used in photovoltaic systems

The application of photovoltaic (PV) as a source of electrical energy in the distributed generation (DG) systems are gaining more attention with the advances in power electronics technology. The one of the key technologies in the PV based DG systems is grid connected inverter that is utilized to interface PV power systems into the utility grid. Multilevel multifunctional grid connected inverters (ML-MFGCIs) are new breed of power converter used in large scale PV applications and have superior advantages such as lower switching power dissipation, lower harmonic distortion and lower electromagnetic interference (EMI) outputs. ML-MFGCIs perform the high quality power from PV systems and provide flexible functionality with improved power quality (PQ), voltage and reactive power support and increased capability of the auxiliary service for the utility grid. This paper presents a detailed analysis of various ML-MFGCI configurations for 1-phase and 3-phase systems and control strategies to compensate the different PQ problems. Almost 100 papers including the practical applications and recent research studies on ML-MFGCIs are reviewed and analysed.