Eigenvalue Sensitivity of Stability Analysis for a Droop Controlled Inverter

The stability issues of the converters that due to the interactions among inverters and passive components in the distributed generation systems have attracted wide attention. For a deep insight into stability analysis, in this paper we propose the sensitivities of eigenvalues to investigate the influences of the control and electrical parameters on system stability. The derivatives of the real and imaginary parts of eigenvalues with respect to system parameters are calculated. A droop controlled inverter was used as the study case, where the eigenvalue sensitivities with respect to the parameters of the components of filer and control system are studied. It shows that the performances of the droop controlled inverter system can be improved by adjusting the values of some parameters according to the sensitivities analysis, which indicates that the eigenvalue sensitivity analysis can provide useful information for system design. The effectiveness of this analysis method is validated by the results of numerical calculation and simulation in PSCAD/EMTDC.