Enabling Grid-Feeding Converters with a Dissonant-Resonant Controller for Negative-Sequence Voltage Elimination

The mitigation of the adverse effects of voltage unbalance in equipment and power quality can be performed by the power electronic converters that interface distributed generators to the grid. Inspired in a resonant controller, this paper presents a dissonant-resonant controller for negative-sequence voltage elimination for a grid-feeding converter connected to the grid. The controller eliminates the negative-sequence voltage at the converter output with a regulable precision, it does not require knowing the grid impedance for successful operation, and it can be a good candidate for parallel operation because it operates not like an integrator, but like an “untuned” integrator. Using the stationary αβ frame, a closed-loop model is developed in a complex space vector built from the complexification of the stationary components. This allows extracting stability conditions for safe closed-loop operation as well as deriving design guidelines for the controller parameters. Numerical and experimental results show the ability of the proposed controller to meet its design goals, thus corroborating the theoretical approach.