The Effects of Saturation on the Armature Leakage Reactance of Large Synchronous Machines

A method which calculates a saturated value for the armature leakage reactance of large turbogenerators is described. The method is applied to evaluate the effects of saturation for various levels of steady-state, short-circuit armature currents. The method makes use of the fact that under balanced, short-circuit conditions, the leakage field in the stator is primarily peripheral. A finite difference method was selected to determine the two dimensional leakage field of the stator windings in the stator slots. Air-gap leakages such as the zig-zag and belt leakage, as well as the tooth-tip leakage, is automatically included in the calculations since the air-gap is considered as part of the problem region.