Adaptive travelling wave protection algorithm using two correlation functions

In this paper, the performance of the correlation function-based travelling wave protection algorithm fbr high resistance faults is investigated. The reason for its inaccuracies is revealed by the lattice diagram. To eliminate its limitation, an auxiliary crosscorrelation function (CCF) is proposed to act as its complement, which takes advantage of the signal that causes the inaccuracies of the standard CCF. For high resistance faults, both the template and the desired signal of the auxiliary CCF have the same prominent feature, which makes them easy to be identified, and the fault location can be acquired from them correctly. An adaptive strategy is designed to select the correct result from the two CCFs so that it can deal with both low resistance and high resistance faults. Simulation results show that the reliability and accuracy of the travelling wave protection have improved significantly.