Abstract: The Generator Terminal Sub-synchronous Damping Controller (GTSDC) suppresses torsional vibrations in the shaft system of thermal power units by inputting damping current signals on the stator side of the generator. The capacity configuration of the GTSDC varies across different sites. For a power plant with the risk of sub-synchronous oscillation, it is necessary to evaluate the oscillation risk and the capacity of the GTSDC equipment. This paper studies a thermal power plant in Shanxi province, analyzing the sub-synchronous oscillation risk of the plant using the complex torque coefficient method and the time domain simulation method. The engineering configuration scheme of the GTSDC equipment was evaluated using PSCAD simulation methods. The response of the GTSDC equipment after commissioning showed that the GTSDC quickly issued a damping current after the oscillation occurred, causing the oscillation to converge to a lower level within 5 seconds. This confirms the effectiveness of the engineering scheme.