An effective method for total transfer capability calculation

Under normal conditions, total transfer capability (TTC) mainly depends on voltage phase change, whereas power loss depends on reactive power distribution. The minimization of power loss is consistent with maximization of TTC. Based on this idea, TTC calculation can be divided into two sub-problems, namely (A) prediction of incremental TTC, which can be calculated by means of simplified linear lossless equivalent circuit and (B) with incremental TTC changes, a nonlinear optimization model minimizing power loss under certain operating mode is to be built to correct the influence of reactive power distribution on TTC. Thereby, an algorithm by which the two sub-problems are alternatively calculated is formed and the effect which is as same as that by complete optimization, i.e., the optimal power flow, is finally realized. Analysis results from several IEEE test systems and a large, realistic test system show that the proposed method is advisable.