Transverse Differential Current-Based Pilot Protection Scheme for Flexible DC Distribution Network

Aiming at the problem that the complex fault transient characteristics of flexible direct distribution network lead to poor reliability of traditional DC protection, this paper proposes a transverse differential current-based pilot protection scheme for flexible DC distribution network. Firstly, the refined model of modular multilevel converter is derived in this paper, and then the fault transient model of flexible direct distribution network is established. The current flowing through the protected line is solved, and the protection criterion of the protected line is constructed by using the difference of transverse differential current under internal and external faults. Finally, a simulation model is built on the RT-LAB platform for verification. The method can correctly identify faults at different fault locations, and has strong ability to withstand transition resistance, with high reliability.