Abstract：Damping torque is an important concept in the study of dynamic stability of electric power system. The value of damping torque coefficient is lack of theoretical basis, when the simplified generator model is used. By utilizing the polynomial approximation method, the damping torque coefficient of generators in AC/DC system is calculated. The method is verified by comparing the damping torque calculation result at the end of transient period considered, by the proposed method and by traditional method based on system linearization. The result shows that, the damping torque coefficient is varying in the transient process. When the system is stable after fault-clearing, the damping torque coefficient approaches a constant value, which is coincident with that obtained by investigation on the linearized model.
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2015, Vol. 16 
