Available transfer capability calculation considering amended thermal limits

A problem based on transient thermal circuit equation and modified thermal limits was studied in this paper, which was involved in mathematic model of optimal power flow(OPF) about available transfer capability (ATC). The weakest lines were found applying modal analysis, then we estimated whether the transmitting capacity was conditioned by the temperature variation of the lines by using constraints of temperature substitute for the thermal limits of the weakest lines. The new model was constructed in order to overcome conservatism of judgement by current capacity, and the latent transmitting capacity will be fully excavated. Then, increased the conductor allowable temperature from 70°C that specified by the present specifications to 80 °C, a great number of both foreign and domestic test datas showed that it will make great profit in the long run. The solution of the optimal power flow problem by a nonlinear primal-dual interior point method is considered. A case study of IEEE-30 bus system demonstrated the rationality and validity of strategies proposed in this paper.