Design of a short-time compensation capacitor for turbine blade vibration suppression

This paper presents a new single-pole switching scheme for depressing turbine–generator blade torsional torque. Since the single-phase fault occurs more frequently in power line accidents, there are many advantages on stability and reliability by using single-pole switching on the faulty phase. Nevertheless, the two healthy phases still maintain power transmission during the dead time between single-pole tripping and line reclosing, which induce significantly negative-sequence current flowing into the nearby turbine–generator. This would cause super-synchronous resonance (SPSR) effect on low-pressure (LP) turbine blades and even result in fatigue damage. The short-time compensation of a grounding capacitor set up at the neutral of the wye transformer is proposed to eliminate this negative-sequence current. Then the induced adverse effect on blades can be precluded.