A Novel Reclosing Algorithm Considering Turbine-Generator Shaft Torque

Various factors exist that cause torsional interaction, such as subsynchronous resonance and switching effects following electrical disturbances. In particular, successive circuit-breaker operation may amplify the turbine-generator shaft torque under unsuccessful reclosing conditions. Thus, in this paper, we carried out transient stability analysis using the integral square error method and derived the relationship between the shaft torque amplitude and reclosing time through analysis of a 2-degree of freedom system under reclosing into permanent fault condition. In addition, we proposed a novel reclosing algorithm with consideration of transient stability and shaft torque amplitude. The performance of the proposed reclosing method was verified in actual 154 kV and 345 kV Korean study systems using the Electromagnetic Transient Program.