Analysis of the Effects of Synchronous Machine Saturation on the Power System Steady State and Transient Stability

Abstract

For solid round rotor body synchronous machines saturation effects are significant in both d- and q-axis, and because of this non linearity, the d- and q-axis magnetizing reactances are depressed to a considerable degree from their unsaturated values under both steady-state and transient operations. In this type of synchronous machine q-axis saturates appreciably more than that of the d-axis because of the presence of the rotor teeth in the magnetic path of the q-axis. This paper first presents a new method to calculate the q-axis saturation characteristic from the existing d-axis saturation characteristic. Next the effects of considering a separate q-axis saturation characteristic on the power system steady-state and transient stability have been presented.