Spline-based controller for power system stability enhancement

The objective of this paper is to design nonlinear excitation controllers for power system stability enhancement. First the direct feedback linearization method is applied to design the excitation controllers. But these controllers have complex structures. Hence, spline techniques are then used to approximate the nonlinear controllers obtained through feedback linearization by polynomials of different degrees and minimize the control effort and yet get a performance similar to the one obtained with the complex nonlinear controllers. A three machine nine bus power system is used as a test system to illustrate the proposed controllers. Simulation results demonstrate that the controllers are effective under different disturbances such as loss of a line and a line to ground fault.