Coordinated Static VAR Compensators and Power System Stabilizers for Damping Power System Oscillations

Technical advantages of coordinating static VAr compensators and power system stabilizers for damping inertial and torsional modes of steam turbine generators are demonstrated. A new control concept for Static VAr Compensators based on using modal speeds as feedback signals, is presented. The concept enables a static VAr compensator to damp all the oscillatory modes as well as controlling the system voltage. A comparison is made between the cases where either modal speeds or generator speed deviations are used as the stabilizing signals of static VAr compensators. The present study shows that coordination of static compensators and power system stabilizers can significantly increase power system dampings as compared with cases where either static VAr compensators or power system stabilizers are used to damp system oscillations. This study is performed on System-1 of the second IEEE benchmark for SSR studies, using an eigenvalue method. The analytical results are verified by detailed digital computer simulation studies, using the BPA´s Electromagnetic Transients Program (EMTP).