Turbogenerator end winding leakage inductance calculation using a 3-D analytical approach based on the solution of Neumann integrals

An analytical technique that can be effectively used for the calculation of the end winding leakage inductance of a turbogenerator has been presented. It is based on a 3-D geometric model of the end winding region in which each coil is modeled as a set of serially connected straight filaments. The calculation of the mutual inductance of the end coils is based on the multiple solutions of the Neumann integral. The method also accounts for the influence of stator core iron on the end winding leakage inductance by using the method of images. The results of the calculations have been compared with the measured values of the leakage inductance for 247 MVA turbogenerator manufactured by KONCAR Generators and Motors Inc., Zagreb, Croatia. The principle of the end winding leakage inductance calculation described can be effectively used for other types of machines and windings as well.