Influence of modulation technique on power quality issues for grid connected converter

Recent development in the power electronic converters, especially those intended for the use in renewable energy applications, emphasize the importance of resolving power quality issues of the grid connected converters. With the increase in number, distributed energy resources will predominantly determine the harmonic content, as the most common power quality indicator, of the grid current and voltages. Therefore, new converter control structures, capable of mitigating harmonics in the injected currents, and consequently voltages, have to be developed. One of the most common path taken for the power quality enhancement is the harmonic compensation. However, even if the significant improvement can be achieved, harmonic compensation can yield different results when paired with different modulation techniques. This paper analyzes the influence of converter modulation techniques on harmonic content of the injected current. Extensive simulation and experimental comparison between two of the most common techniques (sinus PWM and space vector modulation) was performed. MATLAB/Simulink model is used to obtain preliminary simulation results, and the experimental results were acquired using advanced laboratory prototype for testing distributed energy resources. Results show the difference between the two techniques, their advantages and disadvantages. In addition, the influence of the technique on power quality of the injected currents, and their interaction with harmonic compensation is presented.