Design of PID static VAr controllers for the damping of subsynchronous oscillations

Damping of subsynchronous resonance using static VAr compensator (SVC) is investigated. To damp the various unstable torsional modes, a proportional-integral-derivative (PID) controller is used to modulate the reactive power output feedback controller with only one feedback signal (generator speed deviation), the proposed controller is relatively simple for practical implementation. Eigenvalues analysis of the closed-loop system reveals that the PID controller is quite effective over a wide range of operating conditions. Digital simulations using a nonlinear system model are also performed to demonstrate the effectiveness of the proposed controller under disturbance conditions