Patent Document ID: 10082816
Application ID: 15076638
Patent Flag: 1

Claim One:
1. A method of differential protection in the power distribution networks based on phase difference principles, wherein the method comprising the following steps: 1) collecting, via each intelligent feeder terminal unit in association with each loading switches, current and voltage signals of the each loading switch; 2) converting, via each analog/digital conversion plug of the each intelligent feeder terminal unit, the collected current and voltage signals to optical digital signals; 3) transmitting, via Ethernet, the optical digital signals to a differential protection control system; 4) calculating, via a protection logic module of the differential protection control system, phase difference between the corresponding currents at each two adjacent loading switches, wherein at least one of the two adjacent loading switches accords with ΔI ϕ max >n·ΔI T +ΔI dz ; ΔI ϕ max is the maximum value among the 3 phase current mutation values of a corresponding loading switch, n is a set proportional value, ΔI dz is a start value of phase current mutation, ΔI T is a threshold value; 5) determining, via the differential protection control system, the phase difference corresponding to two adjacent loading switches being greater than a threshold; 6) determining a section only between the two adjacent loading switches as a fault section; 7) transmitting tripping control commands to one intelligent feeder terminal unit associated with the fault section; and 8) tripping, via a circuit breaker of the one intelligent feeder terminal unit, the two adjacent loading switches, wherein each intelligent feeder terminal unit includes one circuit breaker, and wherein the value of n being set as 1.25.