Method of calculating the maximum transmission capability with unified power flow controller

Abstract

This study proposed an algorithm for calculating the maximum transmission capacity considering unified power flow controller (UPFC). At the beginning, the equivalent virtual generator, located on ends of UPFC's branch, is obtained based on the source model of UPFC. Then, for the purpose of obtaining the range of transmission power, the maximum (minimum) active/reactive power is treated as an optimising object. Meanwhile, the series voltage and shunt current of the UPFC, as well as other generators’ reactive power, are selected as control variables. As a result, the optimisation model could be formed in UPFC, SSSC and STATCOM modes, respectively, in which buses voltage and transmission limits are also supplied. Based on the characteristics of the above model, the interior point method is used to achieve the optimal solution. In the end, Nanjing western power grid and Suzhou southern power grid are tested to prove the effective and correctness of the introduced algorithm.