Multifunctional DC-link capacitor midpoint inverter control of a distributed generation grid connected system

Distributed generation (DG) is being increasingly embedded in electric four-wire distribution systems which commonly feed three/single phase linear and/or nonlinear loads. This has an impact on power quality of the utility in terms of low power factor, grid current harmonics and unbalance, and neutral current. Conventionally, the DG unit is connected to the grid via a coupling inverter. This inverter can be controlled to operate in multifunctional mode and achieve active power filtering to improve the power quality in addition to the function of power exchange with the grid and the load. This paper presents a DG system connected to the grid via a multifunctional four-wire capacitor midpoint inverter. The converter exchanges the power with the load and the grid and also improves the power quality. A predictive current control technique is used to extract the inverter reference current. The proposed system is modeled using MATLAB/Simulink and the performance is tested for the most conditions in the DG/power system.