Patent ID: 6988042

Claim:
A method for detecting a line-to-line fault location in a power network comprising the steps of: determining elements of a line impedance matrix and a load impedance matrix, and phase voltages and currents at a relay; determining a line-to-line fault distance d by substituting said elements of said line impedance matrix and said load impedance matrix, and said phase voltage and current into a fault location equation based on direct circuit analysis; wherein said fault location equation is derived from a model consisting of said phase voltage and current at the relay, a fault current, a fault resistance and the line-to-line fault distance; wherein the model is based on the line-to-line fault between a-phase and b-phase and described by a model equation: V Sa −V Sb =(1− d )(( Zl aa −Zl ba ) I Sa +( Zl ab −Zl bb ) I Sb +( Zl ac −Zl cb ) +I f R f , where, V Sabc =[V Sa V Sb V Sc ]′: phase voltage vector, I Sabc =[I Sa I Sb I Sc ]′: phase current vector, Zl abc = [ Zl aa Zl ab Zl ac Zl ba Zl bb Zl bc Zl ca Zl cb Zl cc ] : line impedance matrix, I f : fault current, 1−d: fault distance; wherein said fault location equation is derived by using the matrix inverse lemma: (A −1 +BCD) −1 =A−AB(C −1 +DAB) −1 DA, to simplify an inverse matrix calculation; and wherein the fault location equation is derived by direct circuit analysis without using the conventional symmetrical component transformation method.