Intelligent Reflectometer for Monitoring Overhead Power Lines

The paper provides a functional block diagram of an reflectometer for transmission lines with automatic correction of a methodical error. The principle of operation of the device is based on the local method of determining the distance to the fault location: probing pulses are sent to the investigated line and signals received from the fault location are sent, and then the distance to the fault location is determined from the time delay of the reflected pulses relative to the probing pulse. The speed of propagation of a pulse in a line depends on external factors. The main reason for the methodical error of the reflectometer is the instability of the phase velocity of the signal in the line. The phase velocity of the signal, which is taken into account when testing the sample signal, i.e. according to the known distance to the accident site, depends on external climatic factors and dependence on the design of the line with supports. The proposed reflectometer contains an automatic phase velocity correction unit that contains the sensors of climatic factors: a wire temperature sensor, an air temperature sensor, an air permittivity sensor, a ground resistivity sensor and an information processing unit calculating corrections for the phase velocity. The implementation of the correction can be performed without interfering with the device circuit through the shortening sensor, i. e. with minimal interference of a reflectometer design. The reflectometer, containing the developed adaptive amplifier of reflected signals, automatically corrects the amplitude of the signal. Automatic correction can improve the accuracy of measuring the distance to the accident site.