A Unified Modeling Method of Photovoltaic Generation Systems Under Balanced and Unbalanced Voltage Dips

With increasing penetration of photovoltaic (PV) generation systems, it is significant to develop effective models to characterize the dynamic behaviors of actual PV systems under balanced and unbalanced fault conditions. To address this issue, massive field tests have been conducted for on-site PV systems from different manufacturers. Based on the test results, the universal low voltage ride-through (LVRT) response waveforms, including the pre- and post-fault steady states, and fault-duration and fault-recovery transient states, are proposed and formulated. Furthermore, an adjustable factor is proposed to characterize possible LVRT behaviors of on-site PV systems under unbalanced faults. The unified controller is implemented to simulate the dynamics of on-site PV systems of different manufactures under balanced and unbalanced faults. The proposed modeling method has been validated by field tests in practical PV power plants.