Current Harmonic Suppression Strategy for Grid-Connected NPC Converters at Low Switching Frequencies

In this paper, a current harmonic suppression strategy for grid-connected neutral point clamped (NPC) converters at low switching frequencies is presented. This strategy improves the control loop of the NPC converter adopting selective harmonic elimination pulse width modulation (SHEPWM) and the topology of the LCL filter to effectively eliminate current harmonics while ensuring system stability and dynamic response. The simulation results demonstrate that it significantly improves the quality of the output current of the converter, which is beneficial to the stability of the power system.