Adaptive Reclosure Technology for High-Voltage Overhead Lines Combined with Underground Power Cables Based on Travelling Wave Principle

Abstract

For the 110kV and above high-voltage overhead lines combined with underground power cables, a set of adaptive reclosure technology is developed based on 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 reclosure blocking logic is determined, i.e. the reclosure blocking logic is activated if and only if the fault occurs inside the underground cable section of the combined line. In order to test the validity of the presented adaptive reclosure technology, an adaptive reclosure control system is developed based on double-ended travelling wave principle for an actual combined line. In the system, one reclosure control unit is installed at each terminal of the combined line and synchronized by a GPS based power system synchronous clock. The two reclosure control units can communicate with each other through 2M multiplexing optical-fiber channel. At each terminal of the combined line, the reclosure control unit has a reclosure blocking contact signal output (open normally) which is parallel connected to the two ends of the blocking autorecloser hard strap on the protective relaying cabinet for the combined line. Simulation test and actual operation experience show that the adaptive reclosure control technique for HV combined lines based on double-ended travelling wave principle is feasible.