| Abstract |
Controller of grid-connected inverter (GCI) directly affects the performance of inverter-dominated distributed generator. A circuit-based modeling method is proposed to combine the control scheme in software and topology configuration in hardware of a GCI. On basis of the same mathematical model, control blocks are equally changed into circuit models in a GCI. By using the proposed circuit model, mathematical principle and physical nature of proportional-integral (PI) and proportional-resonant (PR) controllers for GCI application are discussed in depth. It concludes that the PI controller cannot tracking sinusoidal reference without error, because of the equivalent capacitor and ac leakage current in circuit model of a GCI. In contrast, due to the extra equivalent inductor and resonance circuit in series compared with PI, the equivalent capacitor in PI is opened, so that the PR control can confirm accurate current-following performance. Selected experimental results are also presented to validate the effectiveness of the proposed modeling method. |
