Implementation of Harmonic Compensation for Three-Phase Grid-Connected Voltage-Source Converter Under Grid Voltage Distortion

This paper presents an implementation methodology for a current harmonic compensation technique of three-phase grid-connected voltage-source converter (VSC), which was applied under the grid voltage distortion and frequency variation. The proportional-integral plus multi-resonant controllers (PIMR) were used to mitigate the high order harmonic current. The PIMR controller was transformed to the discrete-time domain and implemented on a TMS320F28379D digital signal processor. The proposed control scheme was validated with a hardware in the loop (HiL) and with a 5 kW three-phase LCL-filtered grid-connected VSC. The harmonic compensators were used in the dq-frame at harmonic orders 6^th and 12^th for suppression of the grid voltage harmonic orders 5^th, 7^th, 11^th, and 13^th. Results from MATLAB/Simulink simulation and experiments with HiL and hardware implementations were found to be in close agreement. The experimental grid current exhibited excellent harmonic rejection with a total harmonic distortion close to 1% and complied with the IEEE 1547 standard. The grid current can tracked the reference command with a fast dynamic response.

I. Introduction

In recent years, distributed generation (DG) powered by renewable energy sources has gained more popularity due to the limited fossil fuel sources. Meanwhile, the energy demand was creasing leads to problems to the grid, such as grid stability, power quality. The voltage-source converters (VSC) are essential in DG systems. The VSC play an important role in low voltage grid-connected applications such as photovoltaic grid-connected inverters, EV chargers, battery energy storage systems and active power filters. Moreover, nonlinear loads such as the diode/SCRs rectifiers cause power quality problems due to harmonic currents injected into the grid. If the low voltage power grid system has high harmonic currents, they will cause voltage distortions at the point of common coupling (PCC) due to the presence of grid impedance. This effect will be more intense if the position of the nonlinear load is far from the distributed transformer [1].