An investigation into the OLTC effects on voltage collapse

It is known that following disturbances, on-load tap changers act to restor e the load bus voltage and thus restore the load power to near pre-disturba nce level. As the system is probably weakened by the contingencies, this wi ll often over-tax existing supplies due to increased losses and reduction i n power plant ability, and thus voltage collapse may result. This paper dis cusses the less emphasized effect of on;load tap changers from another poin t of view, i.e., how the maximum power transfer limit is affected by on-loa d tap changers. In addition to restoring the load, on-load tap changers als o extend the power transfer ability. Whether the overall effect is benefici al or counter-productive depends on the system ability to balance the amoun t of extended power transfer limit and the amount of restored load by the s ame tap changers.