Wide-area measurement based nonlinear global optimal control for power system stability enhancement

Centralized control using the wide-area information has been suggested to enhance the dynamic performance of large interconnected power systems. According to the inverse system method and LQR optimal control theory, this paper presents a nonlinear hierarchical global controller based on the wide-area information including the on-line measured center of rotor angle and total unbalanced power. Moreover, it has been verified that the optimal control in the sense of linear quadratic state regulator principle for the linearized system is equivalent to an optimal control in the sense of extended quadratic output regulator performance index for the primitive nonlinear system. So, the designed controller is an optimal controller for the nonlinear system digital simulation demonstrates that the multi-machine power system under the nonlinear global control has less settling time, swing times, oscillatory peak value and more critical clearing time and better voltage stability performance than that under PID control and nonlinear decentralized control.