Distortion of PV system-transformer excitation current under low power production

摘要

The relative amount of distortion in the current generated by a PV system under low solar irradiance is known to be quite significant. This paper analyzes such distortion on the utility-side of the interconnection transformer thus including its excitation current. An approximate method that reveals the imbalance and distortion of both the phase and line currents in a 3-legged transformer is presented. The effect of these currents on those generated by the PV system is analyzed. The analysis is illustrated through an experimental test that was conducted on a 12 kW PV system which is connected to the grid through a 3-phase, 30 kVA, Δ-Y, 208/480 V transformer, when operating under low power production.