Effects of sinusoidal load variations on dynamic stability of a parallel AC-DC power system

This paper presents the analyzed results of sinusoidal load variations on a parallel AC-DC power system which has a damping controller to stabilize generator oscillations. The sinusoidal load variations are considered as periodic disturbances with different multiple frequencies based on system mechanical mode. Such disturbances are injected into the studied system by using a quasi infinite bus model and they will cause the studied system to have heteroparametric resonances. Dynamic stability of the studied system is investigated to determine the effects of mechanical-mode frequency as well as its associated multiple times on maximum amplitude of torque angle and rotor speed deviation.