Current Control of a Voltage Source Inverter Connected to the Grid via LCL Filter

The utilization of inverters for the interconnection of distributed generators to the grid requires application of control systems capable of regulating the active and reactive output current, ensuring high power quality levels and achieving relative immunity to grid perturbations. This paper proposes a simple current control scheme, based on the combination of deadbeat and PI control, for a three-phase voltage source inverter connected to the grid via an LCL filter. The control system is analyzed in the frequency domain and an analytical expression for the harmonic content of the output current is derived. Theoretical analysis and computer simulation results validate the stability, fast transient response and robustness of the proposed system to network disturbances and variations in filter parameters.