Analysis of Turbine Generator Steady-State Reactances for Load Conditions

This paper describes variations of turbine generator steady-state reactances for load conditions. When the turbine generator is a small size, magnetic saturation of the stator and rotor core is a problem. Therefore it is important to understand the variations of the reactances for load conditions. The reactances of a 592MVA turbine generator are calculated with d- and q-axis equations considering magnetic saturation and two-dimensional numerical magnetic field analysis. The results are as follows.(1) The equivalent synchronous reactances considering cross-magnetizing phenomenon are smaller than the original synchronous reactances for load conditions.(2) Numerical values of the d- and q-axis mutual reactance and the field and q-axis mutual reactance are at their maximum when the d-axis linkage flux is nearly equal to the q-axis linkage flux under constant voltage.(3) The d-axis synchronous reactance drops with increasing reactive power under constant voltage and active power, but the q-axis synchronous reactance increases.(4) The variation of the equivalent d-axis synchronous reactance with increasing reactive power is similar to that of the d-axis synchronous reactance, but variation of the equivalent q-axis synchronous reactance is different from that of the q-axis synchronous reactance.