On the role of LTCs in emergency and preventive voltage stability control

This paper discusses the effect of load tap changers (LTCs) on the voltage stability of a power system and in particular under emergency conditions. This discussion covers LTCs both on the bulk power delivery transformers, which are normally controlled automatically, and the transformers between higher voltage levels, typically EHV/HV autotransformers, that in many cases are controlled manually. An algorithm to determine taps for the latter that will maximize loadability is presented.