Effect of phase shift on the dynamics of a single-machine infinite-bus power system

Abstract

Power grid dynamics has recently become the focus of intense research. However, the existing studies of power systems essentially assume no energy loss in transmission lines. In this paper, the effect of phase shift (representing the energy loss) on the dynamics of a single-machine-infinite-bus power system is discussed in detail. The results prove that the stability and dynamics of the power system with small damping can be affected by phase shift and it can enlarge the region of instability. This is because the power systems exhibit high-frequency oscillations with small damping and low-frequency oscillations with large damping when phase shift is not considered. As a result, the stability of the power system is easily affected by a phase shift because the power system behaves linearly under small damping less than the critical damping. When damping is small, the phase shift can aggravate the high-frequency oscillations of the power system. Furthermore, simulations confirmed that the smaller the damping, the more easily the stability of the system is affected by phase shift. Moreover, the bigger the phase shift, the larger the region of instability of the power system becomes. These results confirm that the maximum transmission capacity of power system lines with small damping should be enhanced to minimize the energy loss. Furthermore, the effect of damping and maximum transmission capacity of a transmission line on the dynamics and stability of the power system is also discussed in detail.