Fault location technology for high-voltage overhead lines combined with underground power cables based on travelling wave principle

For the 35 kV and above high-voltage overhead lines combined with underground power cables, an accurate fault locating scheme is presented based on double-ended travelling wave principle. Firstly, the fault section is determined on line by comparing the time difference between the arrival time of the fault induced initial travelling wave detected at two ends of the combined line with a setting value. Then, according to the different fault section, the corresponding fault location algorithms are derived. In order to test the validity of the presented fault locating scheme, a locating system is developed based on double-ended travelling wave principle for an actual combined line. In the system, one fault locator is installed at each terminal of the combined line and synchronized by a GPS based power system synchronous clock. The two fault locators can communicate with each other through a 2M multiplexing optical-fiber channel. Actual operation experience shows that the presented fault locating technique for HV combined lines based on double-ended travelling wave principle is feasible.