Patent ID: 7283915

Claim:
Method for fault location in a section of at least one transmission line comprising: measuring the voltages and currents at both ends, A and B, of the section, obtaining the phasors of the positive sequence voltages V A1 , V B1 measured at the ends A and B, respectively, obtaining the phasors of the positive sequence currents I A1 , I B1 measured at the ends A and B, respectively, using an equivalent circuit diagram for the positive sequence quantities, thereby obtaining V A1 e jδ −V B1 +Z L1 I B1 −dZ L1 ( I A1 e jδ +I B1 )=0, where Z L1 —impedance of the whole line for the positive sequence, d—unknown distance to fault [pu], counted from the substation A, δ—unknown synchronization angle, characterised in determining the term exp(jδ) expressed by the formula: ⅇ jδ = V _ B1 - Z _ L1 ⁢ I _ B1 + d ⁢ Z _ L1 ⁢ I _ B1 V _ A1 - d ⁢ Z _ L1 ⁢ I _ A1 calculating absolute values for both sides: A 2 d 2 +A 1 d+A 0 =0 where: d—unknown fault distance, A 2 =|Z L1 I A1 | 2 −|Z L1 I B1 | 2 A 1 =−2real{ V A1 ( Z L1 I A1 )*+( V B1 −Z L1 I B1 )( Z L1 I B1 )*} A 0 =|V A1 | 2 −|V B1 −Z L1 I B1 | 2 X* denotes conjugate of X, |X| denotes absolute value of X solving the equation, thereby obtaining two solutions for a distance to fault (d 1 , d 2 ), and comparing d 1 , d 2 according to 0<( d 1 or d 2 )<1 pu.