An Active Power Recovery Control Method for Post-Fault of Photovoltaic DC Access System Considering Communication Availability

To avoid DC overvoltage, the active power of photovoltaics in a DC access system (PV-DCAS) should be instantly cut down when AC voltage dips, and recover to its pre-fault state after fault clearance (post-fault). However, PVs may fail to switch from reducing active power mode to maximum power point tracking mode during the post-fault period, due to the miss of centralized recovery signal, resulting in the active power loss of PV-DCAS. Consequently, PV-DCAS cannot retain the expected power generation efficiency. This article proposes an active power recovery method for PV-DCAS based on local DC voltage. Based on the analysis of DC voltage during the recovery process, the stage characteristic of DC voltage variation is explored and revealed. A hierarchical criterion that combines the stage features of DC voltage variation and the dynamic response speed of PV is proposed. The proposed approach is validated via real-time digital simulation case studies for multiple AC grid fault scenarios.