Steady state analytical solution of systems with UPFC

The unified power flow controller (UPFC) is a flexible and novel power transmission controller. It provides an efficient control over transmission voltage, phase angle and line impedance. In order to take full advantage of this device, it is necessary to monitor its operating parameters and region of operation. Various models of UPFC device are available but they are not easy to solve analytically. Usually, a numerical approach is used to analyze the circuits containing a UPFC device. This introduces convergence problems. In order to eliminate this analytical solution a mathematical model of a UPFC (see R. Mihalic et al., IEEE Trans. Power Deliv., vol.11, no.1, 1996) is presented in this paper. A flow chart is also presented in order to facilitate the power utility engineers in evaluating the effect of UPFC on the operation of the transmission line.