Study on Power Tracking Excitation Control and Parameters Sensitivity of Dual-Excited Synchronous Generator

Dual-Excited Synchronous Generator (DESG) has two field windings on the rotor. The magnitude and direction of the excitation magneto-motive force (mmf) can be changed by regulating the ratio of the two field currents. This characteristic can improve the power system stability and relieve the transient overvoltage. However, the realization of the functions needs a reasonable excitation control system. In order to improve the operating performances of the DESG, it is proposed a power tracking excitation control strategy (PTECS) which is performed by the incomplete differential on the active power, reactive power and field current. In order to study the dynamic characteristic of the DESG with the PTECS, the excitation control model is coupled with the time-stepping finite element model of the DESG. A 10-kW DESG is developed to verify the correctness of the model. Base on the model, the torque disturbance of a 300-MW DESG with the PTECS is calculated and compared with the results adopting traditional excitation control strategy. The influences of the key parameters of the excitation control system on the damping effect and oscillation period of the DESG are studied. The sensitivities of these parameters are analyzed. Finally, the parameter optimization method of the PTECS is proposed. The results can provide the theoretic basis for enhancing the system damping effect and suppressing the system oscillation.