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В статье изложена методика определения значений «резонансных» частот воздушных линий электропередачи в аварийном режиме однофазного замыкания на землю. Учет наличия рабочих фидеров, подключенных к общим шинам центра питания совместно с аварийной линией, выполнен на основе введения в математическую модель дополнительной линии. Показано, что электрическая сеть оказывает влияние на значения «резонансных» частот в сторону их снижения в сравнении работой одиночной линии и уменьшает их зависимость от уровня тока короткого замыкания на шинах центра питания.

The problem of increasing the reliability of electricity supply is relevant at the current stage of electric power systems development both in the territory of the Russian Federation and in foreign electric power systems. One of the ways to improve the reliability of electricity supply is to prevent the development of emergency situations on overhead power transmission lines as the most important components of electric power systems, which is confirmed by a substantial number of annual domestic and foreign publications. Preventing the development of emergency situations is largely facilitated by early detecting the signs of emergency modes onset in the functioning of all voltage classes’ electric networks. At the same time, the development of intelligence systems for technical and commercial electricity metering opens up new opportunities for monitoring numerous parameters of different operational modes of electrical networks, including those of 6-10-35 kV voltage with isolated neutral operation mode. Numerous works of author’s teams are devoted to the theoretical analysis of the possibility to early detect the diagnostic signs of emergency signals. However, existing publications do not always present the results of field experimental studies in existing electrical networks on the subject under consideration, which demonstrates some discrepancy between theoretical provisions and the possibility of their practical implementation. The present article attempts to assess the possibility of practical implementing the part of theoretical provisions on early detection of diagnostic signs for emergency regimes and, as a result, increase reliability of electricity supply. At the same time, the article presents the results of the field study the basis of which were used to open up current possibilities of early detecting the diagnostic signs of emergency regimes on the example of individual singling out higher harmonic components of currents and voltages, including when using already existing intelligence electricity metering systems installed in the existing electrical distribution systems with the voltage of 10 kV. At the same time, the article demonstrates implementability and further development of online monitoring of emergency modes in electric networks functioning on the example of identifying a single-phase ground fault, which makes it possible to significantly reduce the costs of temporary and material resources when localizing the single-phase closure zone.