Hybrid series compensation scheme capable of damping subsynchronous resonance

The study presents a hybrid series capacitive compensation scheme which is capable of damping subsynchronous resonance (SSR). The hybrid scheme is a combination of a single-phase thyristor-controlled series capacitor (TCSC) and a fixed series capacitor in series in one phase of the compensated transmission line and fixed capacitors on the other two phases. The hybrid scheme creates a phase imbalance during system disturbances. The phase imbalance causes a suppression of the energy exchanged between the electrical and mechanical sides of the turbine-generator and, therefore results in reduction of the growing torsional stresses at SSR mode. The validity and effectiveness of the proposed scheme have been demonstrated on the IEEE first and second benchmark models through time-domain simulations using the EMTP-RV.