SSR damping study on a generator connected to TCSC

The complex torque coefficient approach realized by time domain simulation-the test signal method was adopted in this paper to study the SSR damping characteristics with TCSC. The study system was modified from the first IEEE SSR benchmark model by changing a part of the fixed series capacitor to TCSC. Three different control methodologies were checked, namely: constant current, constant power, and power oscillation damping control. The control models and their principles were also described. Frequency scanning in the subsynchronous frequency range was performed to calculate the subsynchronous electrical damping characteristics of the unit. Impacts of both the parameter settings for the controllers and the thyristor conducting angles of the TCSC on the electrical damping are studied, and results were analyzed in detail. The results show that TCSC greatly reduces the electrical negative damping around the resonant point compared with the fixed capacitor compensation for the three studied control methodologies. It also shows that the conducting angle of the thyristor has a great influence on the damping of the TCSC, the larger the conducting angle, the greater the TCSC reduces the electrical negative damping around the resonant point.