INCREASING THE EFFICIENCY OF RELAY PROTECTION OF THE ELECTRICITY SUPPLY OF A MINING AND PROCESSING PLANT

Abstract The paper presents the results of constructing an efficient relay protection in the power supply system of a mining and processing plant (MPP). A brief description of the MPP is given, as well as the corresponding power supply and equivalent circuits used to calculate short-circuit currents. A statistical analysis of damage in the MPP electrical network is performed, allowing conclusions to be drawn about the nature of damage distribution over the specified period. The analysis of the recorded damages shows that a significant portion of damages are single-phase ground faults, which in most cases turn into multi-phase short circuits disconnected by overcurrent protection (OCP). In order to improve the efficiency and reliability of the relay protection, the MPP power supply circuit is refined and analyzed. Using the refined power supply circuit, short-circuit currents are calculated, which in turn, having numerical values of short-circuit currents, allows calculating the relay protection settings and giving recommendations on the location of its installation and adjustment in order to ensure normal operation of electricity consumers. In order to reduce the number of cable insert damages on the line going to the administrative and amenity building (ABK) and to increase the reliability of power supply to consumers, it is advisable to divide the capacities of the existing 10 kV line into two parallel ones by laying a second line. It is recommended to install a current cutoff on the line going to the ABK, the feasibility of which has been shown by calculations. This will reduce the likelihood of cable insert damage. Data on the overcurrent protection and current cutoff settings are shown on the selectivity map. The presented research results are important for the implementation of educational programs such as EduNet (Phoenix Contact), PowerChute Network Shutdown (PCNS) and Network Management Card (NMC) (Schneider Electric), SITRAIN (Siemens), GIS K-MINE® ("KAI Scientific and Industrial Enterprise" LLC, Ukraine), VENTSIM and others for the training of mining engineers, especially for distance learning during a pandemic such as COVID-19 and other restrictions. The authors consider it appropriate to continue advanced research into high earth fault currents, as well as to develop recommendations for improving the operation of electrical networks, more complete use of existing networks, and ensuring safe service conditions at a mining and processing plant with a large number of mobile 6 kV transformer substations.