Influence of grid-connected inverters on the power quality of the distribution grid

Abstract

Many inverters are quoted as having a PF of better than 0.95 when in reality, the true power factor is between 0.5 and 0.75. This paper describes the influence of grid-connected inverters on the distribution grid. The impact of the voltage distortion from the inverter to the distribution grid is relative small without grid impedance. When the grid impedance is involved, the distortion will become higher and so, more harmonics will be injected into the grid. The impact of the current distortion is especially high at low power output, but decreases fast at moderate or high power. If the background distortion of the grid increases, there will be an increase of the voltage and current harmonics. The specific limits of the EN 50160 and IEC 61000-3-12 could be exceeded at such high pollution.