Operation of multiple inverters in grid-connected large-size Photovoltaic installations

This paper deals with the characterisation of the waveform distortion in the operation of grid-connected photovoltaic (PV) inverters. The PV system assessment is based on experimental results. The data elaborated are taken from the measurements gathered at the terminals of individual PV inverters and at the point of common coupling (PCC) between the PV plant and the grid. For the connection of multiple PV inverters to the grid, the peculiar characteristics of the PV plants, allowing for their distinction with respect to the harmonic loads addressed in the literature, are identified and discussed. Specific harmonic and interharmonic models are constructed on the basis of experimental data, indicating the different ways in which low-order and high-order harmonics sum up at the PCC.