A Supplementary Damping Controller of TCPST on Subsynchronous Oscillation

Damping subsynchronous oscillation (SSO) using Thyristor Controlled Phase Shifting Transformer (TCPST) is investigated in this paper. First, the structure and model of TCPST are introduced. Based on this model the characteristics of TCPST under subsynchronous frequency are analyzed. It can be drawn that though TCPST can change the equivalent system impedance under subsynchronous frequency, SSO wouldn’t be suppressing. Then, a supplementary subsynchronous damping controller (SSDC) of TCPST is designed based on phase compensation method. The results of complex torque coefficient and time simulation in PSCAD/EMTDC verify that this controller has good robustness in each specific scenario and can effectively improve the system stability.