Differential current protection for active distribution networks with dual proportional compensation coefficients

Abstract

The increasing penetration of distributed generation （DG） in distribution networks has exposed poor adaptation of conventional differential current protection schemes. To address this issue， an analysis of the positive-sequence current components output by various types of DGs during faults is conducted. A differential current protection scheme for active distribution networks with dual proportional compensation coefficients is proposed. The scheme constructs braking coefficients and compensation coefficients for fault current phasors， adjusting the phase and magnitude of the positive-sequence current fault components on both sides. This adjustment helps the positive-sequence current components move more easily into the action region of the amplitude-phase plane during internal faults， while ensuring reliable non-operation during external faults. Finally， the proposed protection scheme’s effectiveness under different fault conditions is tested using a model of an active distribution network established in PSCAD/EMTDC. The simulation results demonstrate that the proposed scheme improves both the sensitivity and reliability of differential current protection.

Keywords

• active distribution network
• dg
• differential protection
• amplitude-phase relationship
• current amplitude ratio
• current phase difference
• dual proportional compensation coefficients