Restricting Turbine Blade Vibrations by a Series Compensation Capacitor

This paper presents a modified single-pole switching scheme to depress turbine-generator blade torsional torques. During the dead time between single-pole tripping and line reclosing, the two healthy phases still maintain partial power transmission, which gives rise to significantly negative sequence current flowing into the nearby turbine-generator and may lead to supersynchronous resonance (SPSR) effect on low pressure (LP) turbine blades and even result in fatigue damage. The modified series compensation capacitor is inserted to balance the system and then limits this negative sequence current. Then the induced adverse effect on turbine blades is no longer a problem.