Method for detecting line-to-ground fault location in power network

A method for detecting a line-to-ground fault location in a power network comprising the steps of:

• determining elements of a line impedance matrix and phase voltage and current at a relay;
• determining a line-to-ground fault distance by substituting said elements of line impedance matrix, 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-ground fault distance;
• wherein the model is described by the equation:
• VSab=(1−d)×Zlabc×ISabc+Vfabc,
• where, VSabc=[VSaVSbVSc]′:
• phase voltage vector, ISabc=[ISaISbISc]′:phase current vector, Vfabc=[VfaVfbVfc]′:
• phase voltage vector at the fault location,
• 16 Zl abc = [ Zl aa Zl ab Zl a ⁢ ⁢ c Zl ba Zl bb Zl bc Zl ca Zl cb Zl cc ]
• line impedance matrix, If:
• 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)−1DA, 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.