A parameter-free fault location method for cross-bonding cable based on ranging equations

Abstract

With the increasing application of long-distance high-voltage cables using the cross-bonding grounding method in urban power grids, the effectiveness and accuracy of the single-phase short-circuit fault location method for cross-bonded cables have gradually gained attention. To reduce positioning errors caused by inaccurate or unknown line parameters, a fault location method independent of line parameters is proposed. Firstly, the changes in sheath circulating current before and after the fault occurrence are analyzed, and based on these changes, a criterion for fault identification is established to determine the approximate range of fault occurrence. Secondly, considering the three-phase electromagnetic coupling of cross-bonded cables, an equivalent model for single-phase short-circuit faults in cross-bonded cables is established based on the double-π model. The along-line voltage and current are calculated by deducing electrical quantities at the ends of the cable. Then, the fault location equations are formulated based on the fault section, and the trust-region algorithm is employed to solve for fault distances and unit-length parameters of the cable in each equation group. Finally, a cable fault model is built using the PSCAD/EMTDC simulation platform, and the influence of different factors on the fault location method is analyzed. The results show that the fault location error of the proposed method is around 0.2 %, demonstrating high accuracy.