On the basis of small signal analysis theory

a unified system linearization model for subsynchronous oscillation and low frequency oscillation analysis is established and properly simplified.The shaft model

steam turbine and governor

generator and its excitation system and transmission line model are included.The complex torque coefficient approach is adopted to analyze the system’s mechanical damping and mechanical damping characteristics.Different parameter configurations have different influences on the system’s damping characteristics

the effects of governor system parameters

such as time constant of servomotor position feedback T_2

governor speed feedforward coefficient K_2

time constant of turbine high pressure volume T_(cs) and time constant of reheater steam volume T_(rhs)

as well as the electric parameters

are mainly considered.The results show that

the effects of the governor parameters on the system’s damping characteristics focus on low frequency range

while that of the electric parameters focus on subsynchronous frequency range.The results of the study can provide the basis for inhibiting low frequency oscillation and secondary synchronous oscillation of the power systems.