Load and LTC modeling for voltage stability assessment in EHV network studies

In the last years electric systems, all around the world, experienced voltage stability problems, basically related to their exploitation, near to the limits, caused by market opportunities and progressive growth of loads with low power factor (air-conditioning, electronic devices, etc.). In this paper it is investigated the problem of modeling some specific components of the electric power system, for the simulation of its dynamic response to disturbances, with particular attention to the voltage instability and collapse phenomena. The paper focuses on the analysis of different types of load models and their influence on the voltage stability assessment of electric power systems. Also the effects of LTCs are investigated.