A hybrid approach in study of UPFC effects on the transient stability of multi machine power systems

In this paper, a hybrid method on investigation of UPFC effects on transient stability of multi machine power system has been introduced. Based on the combination of output results of time domain simulation (TDS) and transient energy function (TEF) analysis, study of power system transient stability is converted to the study of transient stability of only one machine, so called critical machine. The effects of UPFC in three basic control mode namely in-phase voltage control (ivc), quadrature voltage control (qvc) and shunt compensation control (sh.c) on the transient stability margin and for various fault clearing times, has been studied. Based on acquired results it can be seen that in-phase and quadrature voltage
control have the most effects on the improvement of transient stability margin