A method to locate a fault from one end of a section of a power line utilizing measurements of current, voltage and angles between the phases at a first end of said section. Symmetrical components of currents are calculated for the current and voltage measurement at the first end. A value of impedance is calculated for an extra link between the terminals with the impedance for the positive sequence equal to:
- Z1AB=impedance for the positive sequence of the extra link,
- Z1LA=positive-sequence impedance of the healthy line. A compensation is determined for the shunt capacitance with the aid of an equation of the form:
B2comp<sub2>—</sub2>1(dcomp<sub2>—</sub2>1)2+B1comp<sub2>—</sub2>1dcomp<sub2>—</sub2>1+B0comp<sub2>—</sub2>1=0 where:
B2comp<sub2>—</sub2>1=A2<sub2>—</sub2>Recomp<sub2>—</sub2>1A00<sub2>—</sub2>Imcomp<sub2>—</sub2>1−A2<sub2>—</sub2>Imcomp<sub2>—</sub2>1A00<sub2>—</sub2>Recomp<sub2>—</sub2>1
B1comp<sub2>—</sub2>1=A1<sub2>—</sub2>Recomp<sub2>—</sub2>1A00<sub2>—</sub2>Imcomp<sub2>—</sub2>1−A1<sub2>—</sub2>Imcomp<sub2>—</sub2>1A00<sub2>—</sub2>Recomp<sub2>—</sub2>1
B0comp<sub2>—</sub2>1=A0<sub2>—</sub2>Recomp<sub2>—</sub2>1A00<sub2>—</sub2>Imcomp<sub2>—</sub2>1−A0<sub2>—</sub2>Imcomp<sub2>—</sub2>1A00<sub2>—</sub2>Recomp<sub2>—</sub2>1.
The zero-sequence current is determined from the healthy line of a section of parallel power lines. A distance to a fault is calculated for the parallel line section. The distance to the fault from the first end is calculated using a quadratic equation of the form:
B2d2+B1d+B0=0 where:
B2=A2<sub2>—</sub2>ReA00<sub2>—</sub2>Im−A2<sub2>—</sub2>ImA00<sub2>—</sub2>Re
B1=A1<sub2>—</sub2>ReA00<sub2>—</sub2>Im−A1<sub2>—</sub2>ImA00<sub2>—</sub2>Re
B0=A0<sub2>—</sub2>ReA00<sub2>—</sub2>Im−A0<sub2>—</sub2>ImA00<sub2>—</sub2>Re.