Analysis of Short Circuit Electromagnetic Force in a Three Winding Transformer Used in Solar System

Due to the increasing of the fossil fuels prices in the past years and lack of these sources, all scientists encouraged to looking for the alternative energy sources. One of these energy sources is renewable solar energy. Power transmission from solar systems to grid is achieved using step up transformers. This type of transformer is energized from two inverter with or without variable frequency. Power transformers are deals with a variety of mechanical, electrical and thermal stresses during normal life time operation. Transient electromagnetic forces cause mechanical stress on transformer parameters where calculation of these forces with traditional methods is extremely complex due to the geometry of the transformer. Accordingly in this study, the electromagnetic forces takes place in the windings of a Photovoltaic (PV) transformer are investigated and for calculation of these forces, the 3D and 2D model of transformer is adapted in the ANSYS Workbench. The analysis of electromagnetic forces during the three line fault on high voltage side of the transformer are performed by the Finite Element Method (FEM) and compared with the analytical results. The numerical modeling technique discussed in this study would be useful in the design stage of PV transformer with regard to evaluate ability of transformer to withstand the short circuit current.