Accurate fault location of hybrid lines in distribution networks

Fault transient traveling waves in hybrid transmission lines are complex and varied. Hence, this study proposes a method for fault location on the basis of the traveling wave polarity, combining single-ended and double-ended traveling wave ranging algorithms. First, the approximate reflected wave time is calculated based on the distance measured by the double-ended traveling wave ranging algorithms. Then, on the basis of the polarity of the traveling wave, the wave reflected from the point where the fault occurs and the joint point of the hybrid line are accurately identified. Finally, after the reflected wave is accurately identified, the fault is accurately located. In the application of double-ended traveling wave method, variational mode decomposition (VMD) and Teager energy operator (TEO) are used to improve the accuracy of the initial fault distance calculation. The algorithm proposed in this study can ignore the errors caused by the time synchronization and the difficulty in identifying the reflected wave. Simulation results show that the algorithm proposed in this study has high measurement accuracy.