A current controller of grid-connected converter for harmonic damping in a distribution network

Harmonic resonance caused by the increased use of shunt-connected capacitors in LCL-filters and power factor correction devices may become a serious power quality challenge in electric distribution systems. A voltage-detection method based on current control is developed to damp harmonic resonances. However, it is susceptible to the mismatch between harmonic conductance and characteristic impedance of distribution feeder. This paper proposes a current controller which allows discrete adjustment of harmonic conductance for both the characteristic harmonic and the non-characteristic harmonic voltages. Thus, the unintentional impedance mismatch can be attenuated to a large extent, and a lower power rating compared to the conventional control method is maintained. Simulations and laboratory tests are performed to verify the overall performance of the proposed controller.