Incipient Fault Detection-Based Active Protection of Photovoltaic DC Integration System

In the photovoltaic DC medium voltage integration system, inter-pole short-circuit faults pose challenges to the protection in tripping faulty branches before converter blocks, consequently leading to a system-wide outage. To address this issue, active protection based on the incipient fault (IF) identification is developed to promptly trip incipient-faulty branches before the emergence of short-circuit faults. However, the minute voltage and current changes during the IF do not provide sufficient information for active protection. Given this, this research thoroughly analyzes the characteristics of the electrical and temperature fields during the IF. The finding indicates that the mutation of arc power can be effectively employed for IF identification. Therefore, an algorithm combining current and temperature measurements is proposed to accurately capture the arc's power mutation during the IF. Subsequently, an active protection criterion is established. Laboratory tests and simulation results validate the reliability of the proposed method in identifying the IF before the occurrence of short-circuit faults.