Thevenin equivalent circuit for the study of high photovoltaic penetration in distribution grids

The electricity grid is unidirectional operating in a passive way and consequently it is not yet ready to accept high penetration of renewable energy sources (RES). Further research is required to assess the impact of distributed Photovoltaic (PV) generation on power quality and establish the necessary measures for the restructuring of the electricity grid to ensure its optimum operation. In this paper, appropriate models are developed in order to assess the effects of PV generation. Thevenin´s theorem is used to develop the equivalent circuit representing the exact distribution grid behaviour. The Thevenin equivalent circuit in combination with a verified PV system model are employed to study the power quality response of the distribution grid in the presence of PV via simulation and the results are compared to actual measurements yielding good agreement.