DQ-Frame Impedance Measurement of Three-Phase Converters Using Time-Domain MIMO Parametric Identification

The dq-frame impedance model is increasingly employed to analyze the grid-converter interactions in three-phase systems. As derived at a specific operating point, it required connect converter actual power grids during measurement. Yet, nonzero grid causes cross-couplings between perturbation and response signals, which consequently jeopardize accuracy of This article analyzes first coupling effect on measured impedance, then proposes multiple-input multiple-output parametric identification method for mitigating effect. Instead using fast Fourier transform, allows obtaining directly from time-domain data. Further, with simultaneous wideband excitations, only single measurement cycle needed. effectiveness verified both simulations experimental tests.