Search

For the analysis of the coupling characteristics of the power system frequency dynamic and power angle oscillation, the mechanism of the two-machine system under disturbances is derived in this paper, and the mechanism of the multi-machine system is obtained based on the extended equal area criterion (EEAC). A quantitative assessment index is proposed based on the Pearson coefficient, which quantified the coupling according to the characteristics of frequency dynamics and power angle oscillation. The influence of power angle oscillation on the frequency dynamic indices is analyzed, and the coupling degrees of between the power angle oscillation and different frequency dynamic indices are assessed quantitatively. The results of the mechanism analysis and case study verify the proposed quantitative indices and show the coupling characteristics of the power system frequency dynamic and power angle oscillation, which provided guidance for optimal frequency and power angle control.

Eigenvalue Method can analyze the operating features of the system. The trajectory section eigenvalue method combines the model and trajectory, and extends the equilibrium point eigenvalue to the unbalanced point of the cross section at any time on the disturbed trajectory, which well solves the non-linearity and the time-varying issues of the system. Based on the theoretical basis of clarifying the trajectory section eigenvalue (TSE) method, the paper establishes a stability evaluation framework based on the time-varying second-order resonant circuit, which extrates the damping feature and frequency feature information in the eigenvalue sequence of the trajectory section, then compares it with the results of signal processing. The influence mechanism of time-varying factors on system stability is clarified, and the advantages of the trajectory section eigenvalue method in stability evaluation are demonstrated.