Determination of Transmission Line Power Transfer Capabilities Using Temperature Dependent Continuation Power Flow

A temperature dependent continuation power flow (TD-CPF) method is developed in this work to capture the effects of changes in load on conductor temperature. The proposed TD-CPF takes into account the changes in conductor temperature and subsequent changes in line resistance at each step change in loading parameter. The method determines the maximum power handling capability of a transmission line not only by considering the voltage collapse point but also checking the line thermal limit. Moreover, by utilizing temperature-dependent transmission line models derived using ambient conditions along the lines (e.g. from a dynamic line rating system), the method can also account for longitudinal variations in conductor temperature and therefore in line electrical parameters. The methodology is tested on an example transmission line and demonstrates quantifiable differences between the estimated voltage stability and thermal limits obtained using the conventional CPF and the developed TD- CPF with line models that account for longitudinal variations in conductor temperature.