Selective harmonic current suppression method for grid-connected inverters based on passivity-based control

Abstract

New energy power generation devices are mostly located in weak power grid areas, where the grid voltage harmonic content is high. Affected by the grid voltage harmonics and switching characteristics, the current of the grid-connected inverter is prone to distortion, which affects the system stability. To solve this problem, a selective harmonic current suppression method based on passivity-based control is proposed for three-phase grid-connected inverters in this paper. Firstly, the Euler-Lagrange (EL) mathematical model of the three-phase grid-connected inverter is established, and the current loop passivity-based controller is designed. Then, combined with the multiple reference frame (MRF) method, an error voltage compensation loop is introduced to independently control the harmonic current. Finally, a simulation model of the system is built and a comparative simulation study is performed with the conventional proportional integral (PI) control and passivity-based control. The simulation results show that the proposed control method which has the advantages of passivity-based control, can effectively suppress the harmonic current of the grid-connected inverter and reduce the design requirements of the filter, thus improving the adaptability of the grid-connected inverter to the weak grid.

Keywords

• harmonic current suppression
• three-phase grid-connected inverter
• passivity-based control
• weak grid
• power quality
• multiple reference frame (mrf)