Fault identification method for insulation damage of DC parallel cables in subway systems based on current deviation degree

Abstract

To address the difficulty of online and accurate identification of insulation damage faults in multiple parallel cables within urban rail transit DC traction power supply systems, this paper proposes a fault identification method based on the Current Deviation Degree (CDD). This method analyzes the deviation characteristics among branch currents of parallel cables and constructs a current deviation degree index to enable rapid localization of the faulty branch. Meanwhile, a system architecture of “edge acquisition + upper-level recognition” is designed, where multi-channel current synchronous acquisition and data uploading are implemented at the edge side, while deviation degree calculation and fault discrimination are performed on the host computer. A DC 750 V multi-branch parallel cable simulation experimental platform is built to validate the proposed method. The results show that under normal operating conditions, the current deviation degree of each branch remains at a low level; however, when an insulation damage fault occurs, the deviation degree of the faulty branch increases significantly, enabling effective identification of the faulty cable. The findings verify the effectiveness and engineering applicability of the proposed method in online fault detection of DC parallel cables.