Integrated DC arc model and DC arc detection approach based on K-line diagram and spectrum integral difference

In the low voltage direct current (LVDC) systems, the occurrence of DC series arc faults poses a significant threat to the safe operation of the system. This paper develops an accurate arc model for the arc fault simulation. The proposed arc model consists the steady-state impedance, high frequency characteristics, and dynamic characteristics of the arc. Additionally, this paper proposes an arc detection algorithm combining the K-line diagram and the spectrum integral difference of the arc current in the LVDC systems. This algorithm can identify four circuit states: normal operation, arc fault, switching action, and load mutation, which addresses the challenge of arc fault detection in complex working conditions. The STM32F407 microcontroller is utilized to design a DC series arc fault detector. Online detection tests demonstrate that the arc faults can be accurately detected and isolated within 37 ms, meeting the requirement of the UL1699B standard, with an accuracy rate of 99.33%. These achievements not only enhance the safety of the LVDC systems but also provide valuable references for the development of arc fault detection technology.