A Low-Voltage Ride-Through Technique for Grid-Connected Converters With Reduced Power Transistors Stress

With more and more distributed energy resources being installed in the utility grid, grid operators start imposing the low-voltage ride-through requirement on such systems to remain grid-connected and inject reactive and/or active current to support grid voltage during fault conditions. This paper proposes a positive and negative sequence current injection method to meet such requirement. In the meantime, the proposed method can reduce the second harmonic ripples in the dc link of the power converter without violating the peak current constraint of the power transistors. The long-term reliability of the converter system can thus be improved.