Effects Of Single- And Three-Pole Switching And High-Speed Reclosing On Turbine-Generator Shafts And Blades

A cause of high cycle fatigue in turbine blades is the resonance of blade vibratory modes with steam excitation. Single-pole switching (SPS) and high-speed reclosing (HSR) can excite 120 Hz torque oscillations that may resonate with the coupled blade-rotor torsional natural frequency and inflict damage on the blades. Using a new advanced continuum model, this paper analyzes the effect of SPS and HSR on the turbine blades of specific machines in the Pacific Power and Light Co. (PP&L) and the Washington Public Power Supply System (WPPSS) systems. Additionally, the stresses on the shaft of the same machines due to SPS and HSR are also analyzed and compared with the stresses on the shaft for a three-pole tripping and a high-speed reclosing operation for the same system disturbance.