Cost-Effective DC Current Suppression for Single-Phase Grid-Connected PV Inverter

Due to the disparity of power modules, asymmetry driving pulses and measurement errors sensors, dc currents may be injected grid-connected photovoltaic (PV) inverters. The current injection cause magnetic saturation transformers. To solve this issue, article thus proposes an effective control strategy compensation method, which does not require any extra sensor hardware circuit. First, root-cause is comprehensively analyzed. Subsequently, a proportional-integral-resonant (PIR) controller proposed eliminate component caused by grid voltage. error estimated from line-frequency ripple dc-link voltage, then it suppressed feedback controller. In addition, rejection capability evaluated, method benchmarked with virtual capacitor-based method. Finally, experimental tests are performed on 1.2-kW single-phase PV inverter verify effectiveness proposal.