Differential current integral based bipolar short-circuit protection method for DC distribution network with blocking converters

Abstract The transient characteristics of the bipolar short-circuit fault on a loop DC distribution network with blocking converters are studied in this paper. A protection principle based on the integrals of the line differential current is proposed after analyzing the characteristics of the line differential current during an internal fault and an external fault. The protection criterion and setting method are also presented. Moreover, after analyzing the adaptability of the proposed protection method under the circumstance where the converters cannot be blocked promptly due to large transition resistance, a criterion for quick blocking is given. The proposed protection method demonstrates such advantages as high anti-transition resistance, none-susceptibility to converter blocking and low sampling frequency requirement, thus can provide selective and reliable protection for the DC distribution network with blocking converters. The proposed protection method is validated by a loop DC distribution network model with blocking converters in PSCAD/EMTDC.