A new method to evaluate the q-axis saturation characteristic of cylindrical-rotor synchronous generator

It has been observed that the values of the magnetizing reactances in both d- and q-axis are reduced significantly from their corresponding unsaturate d values as a result of nonlinearities introduced by saturation under both steady-state and transient operations. In the round rotor synchronous machi ne, q-axis magnetic circuit saturates appreciably more than that along the d-axis because of the presence of the rotor teeth, In the second section, a new method to calculate the q-axis saturation characteristic from the exis ting d-axis saturation characteristic has been presented. We have next calc ulated the saturated values of the d- and q-axis self magnetizing reactance s and mutual cross magnetizing reactances between the two orthogonal axes u nder the steady-state operation. Finally, the effect of saturation, particu larly the effect of q-axis saturation, on the power system transient stabil ity has been presented.