A Novel Fault Location Method and Algorithm for DC Distribution Protection

DC fault current is contributed by various distributed energy resources in dc distribution systems. The tightly coupled dc distribution systems have relatively low line impedance values. The fault current increases fast because of the low impedance. Some converters in dc distribution systems include fault current limiting function. The controlled fault currents at different locations are very close. Thus, it is important to design a reliable and fast fault detection and location method for dc distribution systems. This paper proposes a novel local measurement-based fault location algorithm for tightly coupled dc distribution systems. The proposed fault location algorithm can estimate the equivalent inductance between a protective device and a fault in less than 1 ms. The performance of the developed protection algorithm was validated by numerical simulation and hardware tests.