Tkach V. System for identification of line-to-earth faults in overhead power networks with isolated neutral

Dissertation is devoted to the further investigation of the theory and practice of devices for locating fault in the power supply systems. The analysis of retrospective information of PJSC "Chernihivoblenergo" allowed found the number of emergency shutdowns occurs due to damage to pin insulation (46.8 %) in three-phase systems with isolated neutral. An innovative method for searching a line-to-earth fault location is proposed which based on the identification of the fault current through the pin-type insulation on the overhead line tower, it allows to create a device that will reduce the fault location search and restoration time. Using mathematical modeling, it has been proven that the amount of energy that can be taken from the fault current by the proposed method will be enough to powered the proposed device. The possibility of taking an enough energy to power the device from a line-to-earth fault current without reconstruction the grounding device of the overhead line tower has been theoretically substantiated and experimentally confirmed. A method is proposed for calculating the indicators of reliability and efficiency of functioning of existing power supply systems with proposed identification device. It is shown that in the case of integrating fault identifier into existing power networks, one should expect a decrease in the Expected Energy Not-Supplied to consumers by down to 32%, as well as a decrease in the System Average Interruption Frequency and Duration Index of long interruptions in power supply by up to 40%. The graphical dependencies are obtained that can be used by the management personnel to optimize the structure of service personnel and their location in the area to simultaneously solve the problem of minimizing the operating costs and maximizing the reliability of power supply to consumers in the case of installing an innovative line-to-earth faults identifier devices. An experimental prototype of the identifier device has been created and its working capacity has been shown both in the laboratory conditions and in the conditions of real operation.