Effects of under-load tap changer (LTC) on power system voltage stability

Abstract

The effect of load tap changer (LTC) action on a transformer's adjusted side voltage (usually the secondary side of step-down transformers) is evaluated when the tap position on LTC is raised (lowered) to increase (decrease) the adjusted side voltage. The effects of other measures such as series and shunt compensation and their combination with LTCs are also evaluated. A static representation model of a power system model on a large populated industrial center such as the Puget Sound area of Bonneville Power Administration and the Boston area of New England Power Service are evaluated. The characterization of reactive power voltage (Q-V) relation and real power voltage (P-V) relation curves during a voltage degradation process is studied. The results and experience gained from system specific applications are enumerated.<>