Modular White-Box Model of single-phase Photovoltaic Systems for Harmonic Studies

This paper presents a modular model for single-phase photovoltaic (PV) systems for low-voltage studies. The main aim of the model is to assess the harmonic behavior of these systems. Besides steady state analysis, the model allows also dynamic studies, e.g. of harmonic instabilities. In order to identify and assess possible reasons for such instabilities on the inverter side, an easy interchangeability of the model components is provided based on a modular concept. The modular model can be applied to simulate various PV-system implementations in time-domain simulations. An impedance-based assessment based on the fingerprint method is used to assess the different behavior of the PV-systems regarding their topology and the choice of parameters. A comparison between different Phase Locked Loops (PLLs) and different designs of the grid-side filter is drawn to illustrate the different behavior of the PV-system in a steady state operating point. The model is implemented in MATLAB/Simulink and the Simscape Power Systems library.