Fault Ride Though Control of Photovoltaic Grid-connected Inverter with Current-limited Capability under Offshore Unbalanced Voltage Conditions

The photovoltaic (PV) inverter installed on board experiences the excessive current stress in case of the offshore unbalanced voltage fault ride through (FRT), which significantly affects the operation reliability of the power supply system. In order to solve the problem, the inherent mechanism of the excessive current phenomenon with the conventional fault ride through control is discussed. The quantitative analysis of the current peak value is conducted and a new current-limiting control strategy is proposed to achieve the flexible power control and successful fault ride through in a safe current operation area, which is beneficial to the system reliability. Finally, the simulations of conventional and proposed control solutions are carried out. The results verify the effectiveness of the proposed method.