Active detection fault diagnosis and fault location technology for LVDC distribution networks

Abstract

Under the rapid development of direct current (DC) transmission technology, the interconnection between converter stations in the DC network has been further improved, and a looped network topology has been gradually formed. Practical applications have shown that loop troubleshooting takes a long time to perform and requires substantial field experience, which has considerably reduced the efficiency of troubleshooting and the safety factor of low-voltage direct current (LVDC) distribution networks. The complex, transient characteristics and short duration of power electronic system faults limit the application of passive detection and protection technology, raising difficulties in DC line fault detection and location. To adapt to the development of power systems, this paper presents an active detection fault diagnosis and fault location technology for LVDC distribution networks based on a converter. After a line fault occurs, the fault type is identified by injecting detection signals into the fault line through the converter, and the fault location is determined by calculating harmonic impedance. The method can detect the fault of the system in time to reduce loss when the system on the converter side is faulty but can still run. It effectively utilizes the converter equipment in power systems and does not require the installation of additional detection devices, which is largely unaffected by fault resistance in fault location, and has accurate detection results and fast speed.