Further enhancements in the symmetrical components based improved fault impedance estimation method Part I. Mathematical modelling

This paper develops an approach that can be used for further enhancement of the symmetrical components based improved fault impedance estimation method that has previously been proposed by the authors. In addition to discussing the mathematical basis of the new approach, enhanced and computationally efficient performance equations are presented. In view of the recent advancements in optical transducers and high speed optical fibre communications, the new technique uses sequence components of voltage and current samples obtained from both the ends of the protected transmission line. It is also shown in the paper that the new performance equations are independent of fault resistance. The PC based Alternative Transients Program was used to model a six bus system and to generate fault data. The results of performance assessment studies on this new method are presented and discussed in Part-II of this companion paper.