Dynamic Stability Analysis and Control of Power System Based on Nyquist Array Theory

The dynamic characteristics of the power system have been greatly influenced as the grid-integration of large-scale power electronic devices, such as renewable power generation and direct current transmission. The wide-frequency oscillation dynamic stability problem is prone to occur. In this paper, the Nyquist array theory in the multivariate frequency-domain analysis theory is introduced into the dynamic stability analysis and control of power systems. The power system integrated with doubly-fed induction generator (DFIG) is illustrated in the paper. The forward transfer function matrix and the feedback gain transfer function matrix of the system are derived respectively. Based on the Nyquist array theory, the diagonal dominance characteristics of the system are discriminated. For the diagonal dominance system, the Gershgorin band can be drawn to display the stability characteristics of the system visually. For the non-diagonal dominance system, the system can be transformed into a diagonal dominance system by pseudo-diagonalization, and then the stability analysis and control can be discriminated with Gershgorin band. Finally, the effectiveness of the proposed method is verified by comparison with the eigenvalue calculation results.