An Interharmonics Suppression Control Scheme For PV System with Modified MPPT Algorithm

In general, maximum power point tracking (MPPT) method is employed to ensure the maximum power extraction from photovoltaic (PV) arrays. The perturbation and observation (P&O) algorithm is widely used in PV system due to its simplicity and ease of implementation. However, this algorithm will introduce perturbation which is the main reason of interharmonics injection in PV system. In this paper, an interharmonics suppression control scheme with modified MPPT algorithm was proposed. In the proposed control scheme, the dc-link voltage reference generated by MPPT was used to deduce whether the PV system was operated near the MPP. When the dc-link reference voltages meet the characteristics of three points oscillation three consecutive times, it was meaning that the PV system was operated at the MPP. Then the constant voltage tracking algorithm was trigged. Otherwise, it was operated under conventional P&O MPPT algorithm. The proposed control scheme can suppress interharmonics emission and improve power quality. Meanwhile, it can maintain the MPPT efficiency. Simulations have been carried out to verify the effectiveness of the proposed control scheme.