DC Distribution Line Protection Method Based on Sudden Current Accumulation Features

Multi-terminal flexible DC distribution networks have attracted widespread attention due to their significant advantages in power supply reliability. However, fast and reliable fault identification in DC transmission line protection has become a main problem to be solved for its rapid development. Therefore, a method of differential protection of DC transmission line based on the current sudden accumulations is designed. Based on the analysis of the current mutation characteristics at both ends of the internal fault and external fault, a protection criterion is constructed using the cumulative quantity of mutation current at both ends. Finally,the multi-terminal flexible DC distribution network was modeled on PSCAD/EMTDC4.5 and the protection criteria and key factors are simulated and analyzed. The results indicate that the new protection principle has high speed and sensitivity, can reliably identify faults inside and outside the analysis zone, and has good resistance to transient resistance.