Three-phase multilevel grid interactive inverter for PV systems with reactive power support capability

This paper presents a novel photovoltaic (PV) based three-phase three-level grid-interactive inverter. The proposed system consist of a DC/DC converter, and a three-phase three-level inverter. In order to ensure maximum power point tracking, incremental conductance (IC) technique is used. In addition, to meet international standards for all operating modes, three-phase three-level inverter has been designed and controlled by PI plus grid voltage feed-forward control technique. The proposed system can also operate in various modes to meet smart grids requirements: (1) active power mode in a day time, (2) active and reactive power mode in a day time, (3) reactive power mode at night. To support grid voltage regulation during the day, Mode 1 and Mode 2 are used. These three operation modes bring some benefits such as efficient operation, and reactive power support capability. The proposed system is designed and simulated in Matlab&Simulink software. The simulation results show that the proposed system has an excellent performance under different operating modes.