Effect of grid inductance on grid current quality of parallel grid-connected inverter system with output LCL filter and closed-loop control

Grid-connected inverters (GCIs) are power electronics interfaces to connect distributed energy resources into the grid. In order to improve the performance of distributed energy resources as well as maintain the high power quality of the grid, it is important to understand the characteristic of GCIs with appropriate controllers depending on its applications. This paper presents a study on the effect of grid inductance on quality of the grid current when there are multiple parallel-connected inverters to the grid. The model includes three-phase two-level voltage source inverters, output LCL filter, the grid, and voltage-oriented PI controller with a power controller. Parallel GCI systems are mathematically modeled. Frequency responses of grid current are investigated according to different grid inductances. A parallel grid-connected inverter system is simulated using MATLAB Simulink in order to present the effect of grid inductance on grid current and power quality.