Power Quality Features Improvement In Single -Phase Grid -Connected Inverter With Non-Linear Loads

The increasing application of nonlinear loads may cause distribution system power quality issues. This work presents a control of Single-phase Grid Interactive Inverters with nonlinear loads and a technique for Harmonic compensation and power factor correction of nonlinear loads employing Current Controlled Voltage Source Inverter. This work will focus on the design methodology and the analysis of control strategy which allows the compensation of harmonics and phase displacement of the input current, for non-linear loads. The Utility-Connected Inverter should operate at both Stand-alone and Grid-Connected modes. However, the waveform qualities of the grid current in GridConnected mode and the output voltage in Stand-alone mode are poor under the nonlinear critical load with the conventional control. The impact of the nonlinear load on the grid current is analyzed. Harmonics problem in industrial power systems with non-linear loads are presented. By adding the load current into the filter inductor current loop, the influence of the nonlinear load on the grid current can be eliminated, and the waveform quality of the output voltage in stand-alone mode can be improved. The control method is simple and easy to be achieved. Simulation results from a Full-bridge Grid-Interactive Inverter with a Diode Rectifier load verify the theoretical analysis.