Robust design of dynamic compensator for HV AC power system

The authors present a method to design a robust dynamic compensator for reactive power modulation to improve the dynamic performance of high voltage AC power systems. The effect of nonlinear load on parameters of a dynamic compensator for reactive power modulation using a static VAr compensator (SVC) is investigated. The values of gain and zero of the dynamic compensator, which assign the same complex-conjugate eigenvalues corresponding to electromechanical oscillations, are plotted at different values of load characteristics. The robust dynamic compensator is designed using closed-loop eigenvalue sensitivity with respect to the load characteristics. The rotor speed deviation of the synchronous generator is used as an input signal to the dynamic compensator. The output of the dynamic compensator is used as a stabilizing signal to the SVC. Eigenvalue analysis and simulation results show that a dynamic compensator designed at a constant impedance load model may lead to system instability at a constant active power load. However a robust dynamic compensator improves the system response over a wide range of load characteristics