Line Protection Scheme for DC Distribution Networks Based on Current Waveform Similarity

After a fault occurs in DC distribution networks, the rapidly increasing fault current harms system stability and power electronics in the network. Rapid fault identification and reliable protection schemes are required to enhance the stabilization of the entire DC networks. On the basis of analyzing the characteristics of the fault current waveforms of the DC distribution network, different similarity principles are applied to evaluated current waveforms to identify the internal and external faults of the DC lines. A multi-terminal DC distribution network simulation model is built in PSCAD/EMTDC to validate the effectiveness of the proposed protection scheme. The simulation results show the scheme based on Cosine similarity and Pearson correlation coefficient can detect and locate the fault with great robustness to transient resistance, communication delay and noise.