Harmonic Suppression and Stability Enhancement of a Voltage Sensorless Current Controller for a Grid-Connected Inverter Under Weak Grid

This paper presents the harmonic suppression and stability enhancement of a grid voltage sensorless current controller for grid-connected inverter under weak conditions. Given that inductive-capacitive-inductive (LCL) filters represented as higher-order dynamics cause resonance problems, considerate frequency damping process is required. In particular, phenomenon LCL filter crucially influences quality when connected to with uncertain impedance distorted harmonics. Additionally, there possibility control system will become unstable due changes in parameters, even after damping. order solve these this an active (AD) method by using integral variables state feedback system, which significantly improves harmonics condition. The presented closed-loop scheme only requires measurement injected currents DC-link voltage. Compared traditional methods, reliability robustness proposed are much improved reduced cost. performance investigated presence uncertainty capacitor parameter grids. support theoretical analyses, comprehensive simulation results terms environment both grid. Experimental also 32-bit digital signal processor (DSP) TMS320F28335 2 kVA validate feasibility practically.