Low-Frequency Oscillation Suppression in Grid-Connected DFIG Multi-Band Supplementary Damping Controller Based on Multi-Step Optimization

By optimizing the control parameters of multi-band supplementary damping controller (MBSDC), the problem of multi-low frequency oscillation (LFO) caused by DFIG-integrated can be suppressed, but the single step optimization based on eigenvalue sensitivity has obvious truncation error. To solve this problem, the state matrix of DFIG-integrated system is first established, the LFO modes to be suppressed are screened by eigenvalue analysis, and the MBSDC control strategy is designed. Then, an analytical expression of the relative damping ratio sensitivity of the low frequency oscillation mode is established, and the weighted relative damping ratio sensitivity is proposed to select the parameters to be optimized. On this basis, a multi-step optimization model of MBSDC control parameters is proposed. Finally, the results of single-step optimization and multi-step optimization are compared and analyzed. The effectiveness of multi-step optimization of MBSDC control parameters is verified by small disturbance analysis and time domain simulation.