A static VAR compensator control strategy to maximize power system damping

A study of power system transient stability enhancement through effective use of static VAR compensator is presented. Optimal theoretical control strategy is derived from direct Lyapunov method for multi-machine system model as a control which forces the fastest dissipation of energy released in the system by a given fault. Strategy of this theoretical optimal control uses signal based on the state variables not available at the compensator bus. It is shown in the paper that optimal control signal can be replaced by the time derivative of locally measurable electric quantities. Dynamic properties of two such quantities are compared using eigenvalue analysis. On the basis of this study a current-orientated control strategy is proposed. Its validity and robustness is confirmed by simulation results for nonlinear multi-machine model.