Predicting non-linear torsional dynamics using secondorder solutions

This study develops the principle of superimposed modal interactions (PSMI) for the second-order solutions of transient torques. The PSMI can explain the mechanism for transient torque amplification, and it can also be used to propose a method to identify transient torque amplification according to the initial condition for a transient. The studies are implemented on two systems respectively: the adapted IEEE First Benchmark Model and the practical series compensation system from a Chinese Power Grid. The numerical results show that the proposed method can predict transient torque amplification, and the superimposed modal interactions of several dominant modes result in transient torque amplification.