Enhanced Power Control of Three-Phase Grid-Connected Inverters Using Proportional-Integral-Resonant Controller Under Unbalanced Conditions with a Comparative Analysis between PI and PR Controllers

This paper introduces an advanced approach to achieve real and reactive power control in grid-connected three-phase inverters under unbalanced grid conditions. A novel Proportional-Integral-Resonant (PIR) control strategy is proposed, aiming to address two primary objectives: maintaining balanced grid currents and point of common coupling voltages (PCC), while simultaneously injecting the grid with the desired real and reactive power. Comparative analyses with conventional Proportional-Integral (PI) and Proportional-Resonant (PR) controllers are conducted. The PI controller exhibits a better transient response and lower steady-state error compared to the PR controller. However, under unbalanced grid conditions, the PI controller exhibits oscillations in the real and reactive power output. In contrast, the PR controller effectively manages unbalanced situations and maintains power control. Thus, the proposed PIR method combines the advantages of both PI and PR controllers: superior transient response and lower steady-state error of PI, and effective handling of unbalanced conditions and power control of PR. The simulation and Hardwre’s experimental validation confirm the efficacy of the proposed method.