ASSESSMENT OF THE POSSIBILITY OF INCREASING THE SECURITY OF RURAL 0,4 KV POWER GRIDS BY INSTALLING ADDITIONAL GROUNDINGS

The use of repeated grounding of the neutral wire in rural electrical grids of 0.4 kilovolts is one of the necessary requirements of the Rules for the installation of electrical installations, which regulate the place of their installation and their resistance. In many scientific papers, when studying the mode of a stable single-phase short circuit, repeated grounding is taken into account, while their effect on the magnitude of the emergency current due to changes in their number and resistance is not investigated. (Research Purpose) The research purpose is assessing the effect of the number and resistance of repeated grounding devices on the magnitude of the single-phase short-circuit current in rural power grids of 0.4 kilovolts and on the security of the power transmission line when using them. (Materials and methods) To conduct the study, a computer model of a 0.4 kilovolt rural power grid was used, the prototype of which is a power transmission line with a length of 1000 meters, made with A-35 wire and connected to a transformer TM-250/10/0.4 kilovolt Y/Yn. (Results and discussion) It was found that the use of a grounding device directly near the point of a single-phase short circuit does not affect the magnitude of the emergency mode current. Connecting up to 6 grounding devices leads to an increase in the single-phase short-circuit current by 1.5-4.18 percent, depending on their resistance, compared to a 0.4 kilovolt power transmission line without grounding devices. Using the example of the considered rural power grid of 0.4 kilovolts, it was found that it is possible to increase its security by using additional grounding devices by 0.8-2.15 percent. Other technical solutions to increase the security of the 0.4 kilovolt power grids from single-phase short circuits were also considered. (Conclusions) Based on the results of the study, it was found that the use of repeated grounding devices in the 0.4 kilovolt rural power grid does not lead to a change in the electrical parameters of the single-phase short-circuit mode by more than 5 percent. With this in mind, it is inappropriate to take into account their influence on the parameters of the emergency mode.