ROBUST NONLINEAR CONTROLLER FOR POWER-SYSTEM TRANSIENT STABILITY ENHANCEMENT WITH VOLTAGE REGULATION

A new robust nonlinear controller that has the ability to enhance the transient stability and achieve voltage regulation simultaneously via excitation control for power systems is proposed. The structure of the controller is to add a proportional plus integral (PI) type voltage s ervo-compensator to the existing direct feedback linearisation (DFL) c ontroller; a design procedure is proposed to guarantee the stability o f the closed loop system in a possible working region. By using this r obust nonlinear controller, direct measurement of the power angle for stabilising feedback control and calculation of the target power angle for voltage regulation are not necessary when employing the feedback linearisation technique. Performance analysis and simulation on a sing le-machine infinite-bus power system show that the proposed controller can retain the characteristic of the DFL controller and thus can enha nce the transient stability as well as achieve voltage regulation of t he power system.