Fault location techniques for radial and loop transmission systems using digital fault recorded data

The authors present digital fault location techniques for transmission systems when digital fault recorded data are available at one terminal or two terminals. The systems under consideration are a 115 kV loop transmission system with data available at two terminals and a 69 kV radial transmission system with data available at one terminal. The data under consideration were recorded using digital fault recorders. The conversion of the data to workable data files and the techniques developed to achieve the highest accuracy in determining the fault location are discussed. Intermediate load buses and loads are considered in determining the fault location. An example of the effect of neglecting the presence of these loads is discussed. The fault location techniques are based on both the apparent impedance concept and the use of the three-phase voltage and current phasors. A test case with the exact fault location is presented. The techniques were developed on an IBM PC