Autoidentification Method of the “Trouble Maker(s)” for Internal Instability in Multiparalleled Inverters System

The instability of power systems comprising multiple LCL-filtered grid-connected dc–ac inverters connected in parallel can be caused by any individual inverter due to mutual coupling through the grid impedance. For the stability analysis of a multiparalleled dc–ac inverters system, an effective technique capable to diagnose which particular inverter (i.e., “trouble maker”) causes instability to the overall system has not been developed yet. In this article, a novel autoidentification method is proposed to detect the “trouble maker(s)” of instability in a multiparalleled inverters system, based on the comparison between the root-mean-square value of harmonic voltage at the point of common coupling and the harmonic voltages across the filters capacitors. The theoretical analysis of the proposed identification method is presented in details in this article. Also, simulation and experimental results are provided for the verification of the effectiveness of the proposed technique.