Abstract

The integration of a large amount of renewable energy sources into the new distribution system has significantly altered its fault characteristics, resulting in variable operation modes and limited short-circuit currents. Hence, early arc faults can serve as indicators of impending system short-circuits, and prevent the difficulty of tripping the new distribution system by effectively detecting them in advance. A quantitative analytical model for the early fault current and temperature is developed, and a theoretical analysis reveals the challenges of achieving reliable detection based solely on either current or temperature. A novel early fault detection method that combines current and temperature is proposed, which further utilizes arc power as a complex feature to identify early faults. The proposed feature integrates the promptness of the electrical signal (zero-sequence current) and the high sensitivity and reliability of the thermal signal (temperature), and exhibits higher reliability than the existing method. The validity of the proposed method is verified by PSCAD simulation, field data and laboratory simulated fault tests. '''Key words''': Early arc faults; Fault detection method; New distribution system; Arc model; Compound eigenquantity criterion.