Frequency domain approach to suppress power oscillations of synchronous generators caused by voltage flicker disturbances

A frequency domain approach is used to tune the static excitation systems (SESs) of combined-cycle synchronous generators in the Tong-Shiao generation station in Taiwan to suppress active and reactive power oscillations caused by voltage flicker disturbances. Two electric arc furnaces are fed from this station. The continuous changing of furnace loading has caused voltage flicker disturbances at generator voltage buses, and then induced oscillations of generator active and reactive powers. It is required that the generators have ability to stand voltage flicker disturbances. The parameters of static excitation systems should be adjusted to enhance the damping of electromechanical modes. The frequency spectrum of field measurement voltage waveforms has revealed the frequency components of flicker disturbances. Then the static excitation systems were tuned so that the closed-loop transfer function has a low gain and a suitable bandwidth in the flicker frequency range. Eigenvalue analysis has also been employed to explore the effect of loop-gains, and the dynamic responses of generators were checked by time domain computer simulations.