Small Signals, Large Signals, and Saturation in Generator Modeling

Test and analytic results from recent EPRI-sponsored programs are organized to explain insights into generator modeling. It is shown how small-signal tests and analysis are related to the nonlinear incremental properties of rotor iron. Changes in rotor circuit topology caused by rotation are identified. The large-signal response of rotor circuits is differentiated from the small-signal response. These effects, customarily lumped under the term ``saturation,´´ are separated and differentiated.