Frequency-Domain Modal Analysis for Power-Electronic-Based Power Systems

This letter presents two frequency-domain modal analysis methods, “peak-picking” and “circle fit” used for current control interactions of grid-connected voltage-source converters (VSCs). Differing from the conventional resonance mode analysis, impedances are analyzed with their Nyquist plots, instead magnitude-frequency response, which leads to an accurate prediction on damping behavior system. Experimental tests verify theoretical methods.