Comprehensive protection scheme for lines with unmeasurable branches based on 5G channels

Abstract

There are many unmeasurable branches along with distribution lines. The sensitivity and speed of traditional three-stage overcurrent protection lacks when applied to these lines. Even the phasor differential protection cannot identify internal faults sensitively to maintain sufficient safety under external faults. With 5G communication is penetrating the field of power grid automation, a comprehensive protection scheme for branched distribution lines is proposed. Firstly, analyze negative sequence currents phase characteristics under internal or external faults, and negative-sequence current phase-comparison protection is proposed. Secondly, in some harsh working conditions, 5G communication's synchronization cannot be guaranteed, or even out of step. A positive sequence amplitude differential protection is introduced. Finally, the three-stage overcurrent protection is combined to form a complete set of protection coordination schemes when communication interruption or some extreme situations. A 10 kV active distribution network model is built in PSCAD/EMTDC to verify the proposed protection criteria and scheme. The simulation results demonstrate the effectiveness of the proposed protection criteria and scheme.

Keywords

• negative sequence phase comparison protection
• positive sequence amplitude differential protection
• active distribution network
• 5g communication
• synchronization and loss of synchronization
• lines with unmeasured branches