Harmonic distortion assessment for a single-phase grid-connected photovoltaic system

Nowadays, grid-connected photovoltaic (PV) systems constitute an emerging technology. This has given rise to concerns about their contribution to harmonic distortion levels in utility grids. Valuable insight into the electrical behavior of such a system, including its impact on power quality, can be obtained through extensive simulation studies. In this paper, models are developed with a focus on not only accurate but also fast simulation of grid-connected PV systems. First, time-consuming processes are identified and discussed. These are mainly associated with the semiconductor power switching devices and the non-linear characteristics of the system components (isolation transformer, PV generator). Next, models are developed in order to increase simulation speed by avoiding time-consuming procedures. The validity of the approach is ascertained by comparing simulation results with published measurements. A case study is then performed in order to obtain current and voltage waveforms and, subsequently, harmonic distortion levels. Further simulations are carried out using different values for various system parameters in order to make an assessment of their impact in terms of waveform distortion.