Patent ID: 11921170
Assignee: MAHDI DAVARPANAH
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 0:
1. A method for protecting a low-voltage distribution network comprising a low-voltage side of a three-phase distribution transformer configured to supply electrical power to at least one single-phase load through a respective distribution line of a plurality of three-phase distribution lines, the method comprising:
measuring, utilizing a numerical relay, variations of a periodic neutral-to-ground voltage between a neutral terminal of the three-phase distribution transformer and a local ground node by sampling the variations at a sampling frequency;
detecting, utilizing one or more processors of the numerical relay, a fault in the low-voltage distribution network, comprising:
performing an iterative measurement procedure on the low-voltage distribution network responsive to the variations of the periodic neutral-to-ground voltage being larger than a variation threshold by performing each iteration of the iterative measurement procedure M times at each respective period of the periodic neutral-to-ground voltage where, M
  =
  
   
    F
    s
   
   
    F
    v
   
  
 

 where Fv is a frequency of the periodic neutral-to-ground voltage and Fs is the sampling frequency; and
detecting the fault responsive to the iterative measurement procedure satisfying a fault condition for a predefined number of iterations of the iterative measurement procedure; and

disconnecting, utilizing the numerical relay, the low-voltage side of the three-phase distribution transformer from the low-voltage distribution network responsive to the fault being detected.