Adaptive digital distance algorithm for parallel transmission lines

A digital distance algorithm for parallel power transmission lines is presented. The algorithm requires providing complete measurements from one end of parallel lines. The approach originated initially for fault location aimed at inspection-repair purposes is utilized here for assuring adaptability of a distance relay to the "reactance effect" relevant for resistive faults. Optimal estimation of a voltage drop across a fault path resistance is introduced into the algorithm. As a result of that, determination of the positive and negative sequence currents is avoided. This differs the delivered algorithm from the earlier known forms of the algorithms - designated mainly for fault location purposes. Two forms of the distance adaptive algorithm, i.e., for phasors and with applying a differential equation approach, are considered. The delivered new distance algorithm has been tested with the fault data obtained from versatile ATP-EMTP simulations. The sample examples are reported and discussed.