Abstract:
A special feature of the existing relay protections of power transmission lines (PTL) is their operation on an already existing damage in the electrical network, when the short-circuit current already acts on the primary equipment and on the parameters of the entire electrical network, and when approaching an unacceptable distance to the line of people passes through the human body. To date, there are no relay protection devices capable of shutting down PTL before an emergency or abnormal line operation occurs: when people, mechanisms, or trees approach it at an unacceptable distance. The practical issue of creating a fundamentally new relay protection trigger (RPT) based on measuring high-frequency current in phase wires of PTL is considered. Mathematical modeling of three-phase operation and experimental study of single-phase relay protection triggers in case of emergency and abnormal operating modes on a 50 m long transmission line section were performed. Mathematical modeling was performed in the MMANA GAL Basic V.3.0.0.30 program for the following operating modes: normal, emergency (with single-phase, two-phase and three-phase short circuits), abnormal (interruption of any phase, approaching an unacceptable distance to PTL wires of current-carrying devices). As a result of experimental studies, quantitative indicators of changes in the parameters of the high-frequency current generated in the phase wire during short circuits, approaching the wire of a conducting object and wire breakage have been determined, which can be used as an input signal for triggering the developed circuit. The creation of a new RPT and its use in relay protection terminals of PLT will make it possible to disable both “classic” emergency and abnormal operating modes of lines, as well as damage caused by people and objects conducting electric current approaching an unacceptable distance.
Keywords:power line, mathematical modeling, short circuit, resonant frequency, high frequency current.
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