A novel approach for grid-connected inverter operation based on selective harmonic elimination

摘要

In this article, the feasibility of selective harmonic elimination for grid-connected operation of low voltage DC sources is presented. An appropriate fixed switching pattern is able to achieve good quality current while minimizing switching operations, thereby improving the inverter efficiency. In an attempt to establish the potential advantages over conventional PWM techniques, this article demonstrates the application of SHE in grid connect applications, especially in high power levels while maintaining the ability to provide an independent control of active and reactive powers. The problem formulation is based on using a fixed switching pattern that provides a certain fundamental voltage and eliminates 5(th), 7(th), 11(th), 13(th), 17(th), 19(th), 23(rd), 25(th), 29(,)(th) and 31(st) harmonic order. A power structure consisting of two-stage power conversion is proposed to make this possible, enabling amplitude and phase control of the generated AC voltage from the inverter. An LCL filter has been used for grid interface. The switching pattern and the development of control structure are presented. Simulation studies are discussed and experimental results shown validate the proposed scheme.