Design Improvement of Magnetic Wall Shunts in Large Power Transformers

This paper aims to propose a cost-effective solution for the design improvement of magnetic wall shunts in large power transformers. Conventionally, magnetic wall shunts are composed of identical steel packets which are placed exactly in front of windings to shield the tank walls against leakage flux by providing a low reluctance flux path. However, due to structural asymmetries in power transformers, different sections of the tank walls have different spatial magnetic flux leakage distributions. As a result, each section of the tank walls requires a certain magnetic shunt design. In this study, to enhance the design and reduce production costs, wall shunts are optimized for different sections of the tank walls separately while their optimal positions are also determined. A 200 MVA, 50Hz, 230/155kV transformer is studied as a case study transformer and the optimal designs for the wall shunts are obtained using an iterative algorithm parametric 3D finite element analysis (FEA). The results show that by using the proposed method, an optimized magnetic shunt design with about 30% less material is obtained, a more uniform magnetic flux distribution on the shunts, and a reduced tank power loss which is also as effective as conventional magnetic shunts.