The dynamic interactions among the interconnected power converters may bring in harmonic resonance in a power electronics based power system. This paper addresses this issue in a power system dominated by multiple current- and voltage-controlled inverters with LCL- and LC-filters. The impedance-based analysis approach is adopted and expanded to a meshed and balanced three-phase power network. An impedance ratio derivation method is proposed based on the nodal admittance matrix. By this means, the contribution of each inverter to the system resonance modes can be easily predicted by the Nyquist stability criterion. To validate the theoretical analysis, the time domain simulations and experimental tests on a three-inverter-based system are presented.
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