Analysis of the Interaction Among Power Converters Through Their Synchronization Mechanism

Recent studies have shown the importance of considering the synchronization mechanism of a grid connected converter in its stability assessment. Moreover, it is often taken for granted that synchronization units of grid connected converters operating nearby may interact with each other, but this topic has not yet been deeply investigated in the literature. In this paper, the interaction between synchronization units of grid connected converters is investigated by means of impedance-based analysis. A multiple-inputs multiple-outputs (MIMO) analysis is required and a stability margin is introduced, based on the calculation of the norm of the equivalent grid impedance and equivalent output admittance of the converter. The sensitivity of the stability margin to parameter variations (e.g. grid impedance, bandwidth of the synchronization loop of each converter) is assessed by means of Monte-Carlo (MC) simulations. Time-domain simulations as well as experimental results in a laboratory environment using a power hardware-in-the-loop (PHIL) test bench are performed so as to validate the presented frequency-domain analysis.