Effect of on-load tap changer on voltage stability of power systems with nonlinear load

In this paper we analyze the effect of tap changing of the on-load tap changer (OLTC) on the voltage stability via the calculation of the maximum power transmission and singular induced bifurcation. It is shown that the maximum reactive power increases when the ratio of OLTC increases and the possibility of voltage collapse will be decrease under the same load command. We also get some results on the voltage stability of the power system with OLTC from a singular induced bifurcation point of view. Finally, noting that the voltage instability is directly affected by the load characteristics, we discuss the effect of OLTC on the voltage instability under different static load models.