A nonlinear controller design for SVC to improve power system voltage stability

This paper discusses a nonlinear controller design for Static Var Compensator (SVC) to improve power system voltage stability. A third-order nonlinear dynamical description for the SVC system is developed. Direct feedback linearization (DFL) technique is employed to design a nonlinear controller. The effectiveness of the controller on voltage stability enhancement is studied on a three-bus power system through time simulation and bifurcation analysis. The results show that the collapse time is put off and the subcritical Hopf bifurcation is greatly affected by the controller. The performance of the controller is further compared with that of the conventional capacitor switching. It is found that in some cases the conventional control scheme cannot prevent voltage collapse while the nonlinear SVC control can stabilize the system. The results show that the proposed controller is effective in voltage stability enhancement.