- In some rarely conditions, there may be a suitable location for the SVC before adding the damping PI controller. The system might be stable but with low damping. Although, locating SVCs without the PI controller at other buses under the same conditions causes system instability. Moreover, the power system dynamics are greatly dependent upon SVC parameters beside the system operating conditions and load parameters. Hence, a careful choice of those parameters must be considered to achieve best relative stability.2- An extended eigen-analysis method have been proposed to detect the suitable location from the voltage control point of view for the damping PI-SVC controllers. The settling time and/or the maximum overshoot percentage can be used as a concept for the selection of effective SVC control feedback signal.For parametric inputs which are periodic, the numericalapproach to stability was carried out using the monodromyor transfer matrix approach. from this monodromy approxima-tion method was developed which was formed to give reasonableresults for systems with known stability properties.The stability boundaries for a single degree of freedomsystem under the square wave input have been established.