Grid-tied distributed photovoltaic grid transformer (DPV-GT) systems provide a voltage supply that is never a pure sine wave. DPV-GT systems are subjected to disturbances in the form of harmonics and interharmonics that are superimposed on the supply voltage. This causes the power quality phenomena which can be caused both by voltage and current harmonics. The harmonics are defined as multiples of frequencies of the fundamental component (i.e., 60 or 50 Hz) and are defined by their spectral distribution and values in the frequency range as defined by IEEE P1-433-A. In addition, there are interharmonics that are voltage or current harmonics with frequencies not as multiples of the fundamental frequency but as discrete frequencies or as a part of broadband frequency as defined by IEC 61000-2-1.