Improved SHM-PAM-based five-level CHB inverter to fulfil NRS 048-2:2003 grid code and to apply as shunt active power filter with tuned proportional-resonant controller for improving power quality

摘要

This study proposes a selective harmonic minimisation-pulse amplitude modulation (SHM-PAM) technique utilising least number of switching based on optimised waveform pattern for five-level cascaded H-bridge (CHB) inverter to satisfy the NRS 048-2:2003 grid code standard. Here, particle swarm optimisation method is used to evaluate the solution of the optimised switching angles and variable DC-link voltages. A comparison between the proposed SHM-PAM and conventional selective harmonic elimination-pulse width modulation (SHE-PWM) techniques has been carried out by harmonic performance analysis (total harmonic distortion (THD), weighted current THD and harmonic loss factor) and loss analysis (conduction, switching and their cumulative losses) of the switches of five-level CHB inverter under different load power factor angles for medium-voltage application. The performances of the conventional SHE-PWM and proposed SHM-PAM techniques are examined through experimentation using a three-phase five-level CHB inverter. Finally, the proposed technique based 5-level CHB inverter is applied to shunt active power filter using tuned proportional plus parallel resonant current controller for improvement in power quality under non-ideal grid conditions.