The Effect of OLTC on Static Voltage Stability Limit

Voltage stability problems caused by on-load Tap Changer (OLTC) action and load dynamic characteristics are more complicated and not easy to grasp. By means of the P_max - Φ and V_cr - Φ curves, this paper analyses the influence of OLTC on the static voltage stability limit, and studies the critical variable ratio corresponding to the OLTC adjustment. The P_max - Φ and V_cr - Φ curves gradually shift upward with the continuous increment of transformation ratio n of on-load Tap Changer; the P_max - Φ and V_cr - Φ curves gradually shift down with the continuous decrease of OLTC transformation ratio n. During the adjustment of OLTC ratio, its range can not exceed the adjustment area determined by the critical variable ratio. Finally the example simulation proves that P_max - Φ and V_cr - Φ curves can well describe the influence of OLTC adjustment on the static voltage stability limit.