Study on the complex nonlinear features of hydrogenerator caused by multiply factors

The operation behaviors of large hydro-generators under the abnormal or critical operation condition are studied systemically by means of FE method. Through three cases that the ratio of field current to d-axis current, the field current and the power factor angle are fixed respectively, the nonlinear features of hydro-generator are researched and some curve series are obtained. It is found that the saturation characteristics differ widely under various conditions and the factors, main magnetic route and leakage magnetic field, which affect the nonlinear features are analyzed systematically. Considering complex nonlinear features, a method of calculating the field current under any steady operation is brought forward.