Steady-state power/rotor-angle characteristics for synchronous machine including hysteresis

Theoretical steady-state power/rotor-angle expressions are derived for a salient-pole synchronous machine with hysteresis in the field and armature members represented by idealised elliptical flux-density/magnetising-force characteristics. It is shown that the effect of hysteresis may be represented in an equivalent machine simulation by modified unequal values of direct and quadrature axis effective armature resistance. The displacement angle between m.m.f. and flux is measured by different methods, and, for a reversal of rotor angle movement, an approximate method is described to represent a recoil line on the power/angle characteristic. Predicted and measured characteristics are in close agreement and show that the effect of hysteresis is to increase the steady-state-stability limit.