Failure Risk Assessment of Grid-Connected Inverter with Parametric Uncertainty in LCL Filter

Grid-connected inverter failure may be caused by outliers of a population of units in field operation, due to the LCL filter parameter uncertainty. This article proposes a probabilistic framework to analyze the impact of multiple filter parameter variances due to component tolerances, operating points, and aging effects. Both robust stability and filter performance are selected as the risk of failure. The robust stability of the grid-connected inverter is quantified by the structured singular value. The total harmonic distortion of the grid current is estimated to evaluate the filter performance. A case study on a three-phase inverter is performed to verify the proposed method through hardware-in-the-loop simulation and physical prototype testing.