DAMPING TORSIONAL OSCILLATIONS BY A SUPERCONDUCTING MAGNETIC ENERGY STORAGE UNIT

ABSTRACT

This paper investigates the effect of a superconducting magnetic energy storage (SMES) unit on the repressing of torsional oscillations in a capacitor compensated power system. The IEEE Second Benchmark Model is employed. To increase the damping of torsional modes, an auxiliary controller, proportional-integral-derivative (PID) or lead-lag, is employed to control the power modulation of the SMES unit according to generator speed deviation. The gains of the proposed auxiliary controller are determined by a pole assignment method where the eigenvalues of the torsional modes are placed at a prespecified position. Eigenvalue analysis and computer simulations of the studied system show that the SMES unit provides adequate damping torque over a wide range of operating conditions. Stability investigation shows that the PID controller is better than the lead-lag controller. The SMES unit also ensures a stable system when one of the parallel lines is out of service.