"电网不平衡下光伏并网系统直压控制策略优化与验证"

The two-stage photovoltaic grid-connected system collects photovoltaic power to the low-voltage DC bus, which is then fed into the grid through grid-tied inverters. This system can meet the local load demand and achieve on-site consumption of solar energy, providing higher energy efficiency compared to traditional decentralized inverter systems. However, when there is voltage imbalance or drop in the AC grid, the system may experience issues such as voltage rise and double-frequency voltage fluctuation on the low-voltage DC bus. To address these challenges and ensure the stability of the system, a control strategy is proposed in this study. It involves maximum power point tracking and switching between voltage control modes for the front-end DC/DC converter. Additionally, proportional-resonant control is implemented to mitigate voltage rise and double-frequency voltage fluctuations on the low-voltage DC bus. This control strategy aims to stabilize the voltage and improve the quality of electrical energy. Simulation and experimental validation are conducted using a single-phase voltage drop scenario as an example to verify the effectiveness of the proposed control strategy. The results demonstrate that the strategy successfully addresses the voltage imbalance and drop issues, ensuring the stability of the system and enhancing the overall energy quality.