Impact of increased line loading in considering the conversion of fixed line reactors on the 765kV Cape corridor into variable types

The supplies into the Western Cape system consist of a well-developed system, comprising a number of 400kV lines and a 765kV corridor in parallel. The 765kV lines were introduced later when it was established that improved in voltage stability of the power system obtained by building further 400kV lines was not acceptable. In an effort to improve the utilization of this infrastructure, the possibility of converting fixed line reactors into variable type is under consideration at present. In the companion paper, it was established that there might not be techno-economic benefits in making the reactors on the 765kV corridor variable if the loading of the lines was low. Further to this, it was shown in another associated paper that by introducing series compensation in the Cape's 765kV corridor, it was possible to substantially increase its loading. In this paper, first the loading of the 765kV corridor is improved by introducing series compensation. Thereafter, the possibility of making the reactors variable, and the impact of this exercise on voltage stability limit of the Cape corridor, is evaluated.