Patent ID: 6924647
Filing Date: 2005-08-02
Classification: G01R,Y04S

Abstract:
1. Method for calculating the distance to fault in a section of a power transmission network (AA-BB), which section is arranged with line terminals at both ends, each terminal comprising impedance relays (AA, BB), comprising the steps of, at the occurrence of a fault: measuring the apparent impedances by each relay ( measuring the relaying currents (| determining the type of fault, characterised in checking whether the fault involves a fault resistance or not according to where Z 1L —impedance of a whole line for the positive sequence and, if fulfilled, solving a quadratic equation for complex numbers according to where resolving the quadratic equation for the real and imaginary components obtaining two quadratic equations for a fault distance in which the coefficients are real numbers, combining the two equations and obtaining a distance to fault as: or, if not fulfilled solving a quadratic equation for real numbers according to obtaining two solutions for the distance to fault according to comparing the solutions as where pu is the length of transmission lines between the line terminals.