Optimal Design Method of Flexible Excitation System for Improving Power System Stability

Providing sufficient damping over the full frequency range of the low frequency oscillation (LFO) is a challenge for the power system stabilizer (PSS). The flexible excitation system of the synchronous generator is a novel structure with full-controlled devices, which has two damping channels. One is controlled by PSS, and another can be controlled by the reactive power damping controller (RPDC) to improve the damping over the lower-frequency range. A novel structure, avoiding the limitation of the excessive higher-frequency gain on lower-frequency damping, is adopted in RPDC. The parameters design method of the flexible excitation system is proposed. A SMIB system is established in RTDS (real time digital system), and various oscillation frequencies (i.e. 1.2 Hz, 0.5 Hz, and 0.3 Hz) are obtained by adjusting TJ. The comparisons between the flexible and conventional excitation system show that the flexible excitation system can provide more damping to reduce the steady time, decrease the oscillation amplitude, and improve the power system stability over the full frequency range of LFO, especially over the lower-frequency range.