Method of fault location in parallel transmission lines with series compensation

A device for locating a fault (F) in a section of parallel transmission lines comprising:

• calculating member arranged to automatically calculate, on the basis of current and voltage values measured adjacent to one end of said section and a known impedance of the lines, a distance between a measuring point and the fault;
• and
• wherein the calculating members are arranged to determine, on the basis of information about the type of fault in question and complex quantities of the measured values and using a network model, the fault distance as the solution of an equation Ax2−Bx+C−Rf=0;
• wherein x is a variable fault distance and Rf is the measured fault resistance;
• wherein the parameters (A, B, C, D) comprise the phase components of locally measured currents and voltages and are obtained from calculating from a measuring point to the fault location along the both parallel lines;
• wherein the equation is resolved into its real and imaginary parts:
• Real(A)x2−Real(B)x+Real(C)−Rf=0
• and
• Imag(A)x2−Imag(B)x+Imag(C)=0;
• wherein the fault distance is derived from the imaginary part, as
• x=xa, if Imag(A)>0,
• and
• x=xb, if Imag(A)<0,
• wherein x a = Imag ⁡ ( B ) - D 2 ⁢ Imag ⁡ ( A ) , ⁢ x b = Imag ⁡ ( B ) + D 2 ⁢ Imag ⁡ ( A ) , ⁢ and Δ=[Imag(B)]2−4Imag(A)Imag(C).

A computer program product selectively comprising computer code means and software code portions for automatically locating a fault (F) in a section of parallel A.C. transmission lines by making a computer or processor perform the steps of:

• receiving values of currents and voltages of both the lines at a measuring point arranged at one end (A) of the section;
• calculating a fault distance x from the measuring point to the fault location along the both parallel lines as a solution of an equation Ax2−Bx+C−Rf=0;
• wherein the fault distance x is a variable and the fault resistance (Rf) and parameters A, B, C, D depend on phase components of the locally measured currents and voltages;
• wherein the equation is resolved for the real parts and the imaginary parts respectively;
• and
• reporting the fault distance x.