An OPF based approach for static voltage stability evaluation considering heat balance rule of overhead line

In this paper, overhead lines' heat balance rule (HBR) is considered in static voltage stability margin (VSM) evaluation issue and an optimal power flow (OPF) based approach for VSM evaluation is proposed. It captures the coupling nature between current & temperature of overhead line and also considers the influence of temperature on series resistance of conductor by introducing heat balance equation (HBE) of overhead lines as equality constraint and temperature as an state variable in optimal power flow which maximizes the VSM index. The proposed approach is capable of improving evaluation accuracy and the evaluation results of consider and disregard HBR of transmission line are compared via simulation.