Control Of Grid Connected Converters Under Unbalanced Grid Faults

A grid connected inverter with an unbalanced voltage at the point of common coupling creates oscillation in DC link voltage at twice the grid frequency and inject highly distorted current into the grid. In this paper analytical expression for oscillation of DC link voltage and distortion in current injected to the grid are derived. Two control strategies for grid connected inverter are implemented and the analytical result obtained for dc link voltage oscillation and distortion in grid current are verified through simulation and experimental results.