Mechanism of impact of governor control on power system dynamics and introduction of boundary frequency

This paper presents an investigation on the mechanism of the impact of the governor control on power system dynamics, and an introduction of boundary frequency. The well-known Hefferon-Phllips math model has been extended to include the math model of the turbine and its governor. By using this model the impact can be divided into the synchronizing and the damping torques. Based on the analysis of the frequency response, a new concept of the boundary frequency has been drawn out and that provides a performance index in characterizing the nature of the turbine and its governor in system dynamics. The damping provided by governor will be opposite in polarity, if the oscillation frequencies are located in different sides of the boundary frequency. This study also provides the values of the boundary frequencies for thermal and hydro generators under different control input signals Δω or ΔP_E. Study has also been conducted for input signals Δω and ΔP_E.