An adaptive approach in digital distance protection

Adaptive distance protection can be obtained by forming an adaptive control system, and rules about information, functions, and time sequence must followed in its design. Three adaptive methods are suggested to deal with the following problems: (1) the effect of frequency variation, (2) the effect of fault resistance in single-phase-to-ground faults, and (3) the effect of power swings in power systems. A prototype of digital distance protection has been designed and tested on a 500 kV dynamic power system model. Tests results show that the performance of distance protection can be improved by the adaptive methods