Current Quality Improvement of a Solar Inverter System Connected to Weak Grid using Multiple Resonant Components in Weighted Grid Voltage Feedforward

Grid-tied voltage source inverters, used to convert DC power generated by photovoltaic (PV) sources into AC power for injection into the grid, inherently generate voltage and current harmonics at the Point of Common Coupling (PCC). Although inductor-capacitor-inductor (LCL) filters effectively attenuate the harmonics generated by the inverter, they can also create resonance, potentially compromising the stability of grid-connected systems. Various methods, including active damping through filter capacitor current feedback, have been employed to mitigate these issues. Thorough feedforward control of grid voltage is considered an effective method for improving the quality of injected current in grid-connected inverters. In this paper, a novel control strategy for grid-connected solar array power conditioning systems is proposed, utilizing a weighted thorough feedforward scheme of grid voltage based on multiple resonant components. The proposed method significantly enhances the system's ability to suppress PCC voltage harmonics by incorporating a set of quasi-resonance sections into the feedforward path of the network voltage. With proper design of these quasi-resonance components, the phase delay created by digital control is resolved, PCC voltage harmonic attenuation is further enhanced, and the stable operation of the grid-tied solar array power conditioning system is improved under harmonic-polluted grid conditions.

کلیدواژه ها:

active damping ، Fully weighted grid voltage feed forward ، Grid-Connected Inverter ، Inductor-capacitor-inductor filter ، Solar Power generation system