Damping torque comparison and analysis of UPFC based on phase angle control and vector control

This paper conducts an in-depth study on the damping characteristics of the damping controller added on the UPFC when two different control strategies are applied (vector control strategy and phase angle control strategy). Firstly, the structure of the UPFC and the principle of the vector and phase angle control strategy are presented in this paper. Then the linearized model of the system with a UPFC installed is established. Based on the model, the damping torque analysis (DTA) method is introduced and then applied to analyze the damping effect of the additional damping controller to the inter-area oscillation mode in the two area four machine system with a UPFC installed. It is found that the damping provided by the damping controller added on the UPFC with the phase angle control strategy is larger than that provided when the vector control strategy is applied. The correctness of the analytical conclusions are verified by both the modal analysis method and the time domain simulation where the phase compensation method is used to design a damping controller.