Study of the transient time constant of the model synchronous generator

In order to study the effects of the much larger stator and rotor resistance (in per unit, compared to the normal one) on the transient time constant in the model synchronous generators, this paper deduce the improved analytical expression of exciting current under no-load and three-phases´ short circuit situation, with the resistance of stator and rotor considered. The comparison of the results from improved analytical solution and field test as well as the calculation results of PARK equations and traditional analytical solution shows the correctness and validity of this model. The results reveal that T_d´ of the synchronous generator start with a small decrease and then increase gradually as the stator resistance increased, and T_a of the synchronous generator start with a small decrease and then increase gradually as the rotor resistance increased.