Single-phase grid-tie inverter control using DQ transform for active and reactive load power compensation

This paper presents a current control for single phase grid connected inverters. The method allows for inverter active and reactive power control. The method uses the Direct-Quadrature (DQ) synchronous reference frame transformation for single-phase converters. This method transforms an orthogonal pair consisting of the inverter output current and a time shifted version of this current from a stationary frame to a rotating frame synchronous to the fundamental output frequency. Alternatives to using the time shifted current are discussed. The steady state current components in this rotating DQ frame are DC values and thus PI control methods can be used with zero error. A household scale grid-tie inverter is used as an example application of this method. A Simulink simulation model and results where the inverter output is controlled to match a local load´s active and reactive power demand is presented.