The de-excitation is the last protection line for the generator when it＇s broken- down. The reliable and quick de-excitation ability dominates the safety level of the gen- erator. In this paper the three conventional de-excitation methods for the synchronous generator in unload condition are studied, the effect of damping winding is considered and Park equations in d,q axis are used. Specially, no-load characteristic （NLC） of gen- erator is represented by analysis expression, so the effect of saturation of NLC on de-ex- citation is included....
