《2区-Ground+currents+in+single-phase+transformerless+photovoltaic+systems》.pdf

PROGRESS IN PHOTOVOLTAICS: RESEARCH AND APPLICATIONS Prog. Photovolt: Res. Appl. 2007; 15:629–650 Published online 4 May 2007 in Wiley InterScience () DOI: 10.1002/pip.761 Applications Ground Currents in Single-phase Transformerless Photovoltaic Systems ´ *,y ´ ´ ´ Eugenio Gubıa , Pablo Sanchis, Alfredo Ursua, Jesus Lopez and Luis Marroyo Department of Electrical and Electronic Engineering, Public University of Navarra, Pamplona, Spain The relative weight of the energy generated by means of renewable sources is constantly increasing. Among all these sources, the photovoltaic (PV) systems present the higher and more stable relative growth. However, the PV system is still too expensive and a significant effort is being done to increase the efficiency and reduce the cost. Concerning the PV inverters, this has lead to the elimination of the low frequency (LF) transformer that has been traditionally included. The LF transformer provides isolation from the grid but reduces the PV inverter efficiency and increases its size and cost. However, the elimination of the transformer might generate strong ground currents, which become now an important design parameter for the PV inverter. The ground currents are a function of the system stray elements. However, there is no simple model and procedure to study the