A Negative Feedback Excitation Control Strategy for Suppressing Sub-synchronous Oscillation of Synchronous Generators

In this paper, a negative feedback excitation control strategy is proposed to suppress the sub-synchronous oscillation of synchronous generators. The development process of the vibration mode energy of the mechanical shafting, and the oscillating electromagnetic energy of the electrical circuit, are studied when the sub-synchronous oscillation occurred. This paper pointed out that most of the oscillation energy exists in the form of vibration mode energy of the mechanical shafting. Based on the root locus analysis, a negative feedback control strategy is proposed to suppress the vibration mode. The instantaneous electromagnetic torque could be controlled by the instantaneous field current, while the instantaneous field current could be controlled by the instantaneous excitation voltage. The electromagnetic transient simulation showed that the proposed strategy could effectively suppress the sub-synchronous oscillation, which caused by small disturbance or even large disturbance.