Rate-of-Current Based Protection for DC Distribution Network

When fault occurs in the DC distribution network, the fault current rises rapidly, and it is difficult to develop fast and reliable relay protection. In the paper, by analyzing the response characteristics of each circuit when bipolar fault occurs in the DC distribution line, a fast DC protection scheme based on communication is proposed, which use the contrary change rate of current before and after the fault point during the transient process of capacitor discharge as the protection criterion. Finally, the feasibility of the proposed method is verified by simulation with PSCAD/EMTDC, and it proves the scheme has certain superiority, avoiding problems such as the setting and matching difficulties in conventional current protection methods.