A Phase-Shifting DC-Link Voltage Control Strategy for Parallel Inverters to Suppress Interharmonics in PV Systems

The large-scale installation of photovoltaic (PV) systems leads to interharmonic problems, which greatly affect the power quality of power system. It has been revealed that the dc-link voltage oscillation caused by the perturbation maximum power point tracking (MPPT) algorithm is one of the main causes of interharmonics. To address this issue, a phase-shifting dc-link voltage control strategy for parallel inverters to suppress interharmonics in PV systems is proposed. In this method, the relationship between interharmonic characteristics and reference dc-link voltage is the basis for suppressing interharmonics. The proposed system contains two parallel inverters, whose reference dc-link voltages are antiphase. Therefore, the interharmonic current can be eliminated with each other. Simulations and experiments have been constructed to verify the effectiveness of the proposed interharmonic suppression strategy.