This paper proposes a theoretical calculation method for obtaining the impact load and dynamic response of shafting during the rapid engagement process of a combined gas turbine and gas turbine (COGAG) power plant.

According to the mechanical relationships between various components in the meshing process of a synchro-self-shifting (SSS) clutch, a dynamic analysis model of the clutch is established, and the dynamic simulation and bench test during the rapid engagement of COGAG are carried out.

As the simulation results show, when the damping dashpot functions, a significant torque impact occurs on the clutch spiral spline which can result in a strong dynamic response on the shafting. It is also found that the relative position of the ratchet and pawl is random, which can cause the peak torque impact and dynamic response of the shafting to fluctuate within a certain range. Through a power plant experiment, the accuracy of the impact load calculation method and the randomness of the impact amplitude are verified, and the errors of the maximum and minimum torque response amplitudes are 3.56% and 8.86% respectively.

This paper finds that the rapid engagement of COGAG can produce an obvious torque impact which can affect the safety of the power plant. As such, it can provide references for the operation safety evaluation of COGAG power plants.