Input impedance of voltage source converter with stationary frame linear current regulators and phase-locked loop

Small-signal stability in balanced three-phase systems can be analyzed using Generalized Nyquist stability Criterion (GNC), which is based on source and load impedances in synchronous rotating (d-q) frame. The derivation of d-q input impedance of controlled power electronics converters is relatively easy in the case that current controller is implemented in d-q reference frame, while the analysis in the case of stationary (α-β) reference frame controller is missing. This paper addresses such analysis for Active Front End (AFE) rectifier with different α-β frame linear current regulators, with a focus on the resonant controllers, and Phase-Locked Loop (PLL). A comparison in terms of input impedance of stationary and rotating frame current controller is also reported. Simulation and experimental results verify the validity of the proposed analysis.