Ensuring the security of the energy system by predetermining the size of inrush current at power transformers coupling

The current shock occurring when connecting the transformers to the mains can lead to electrical and mechanical stress in transformers, which can cause failures compromising the reliability of the power system the equipment (transformer) is part of. In order to prevent the occurrence of major failure at the level of the power system, the project we propose aims at detecting the size and the time of occurrence of the transient current as early as the design stage. Aimed at ensuring the reliability of the power system, for predetermining the size of the transient current occurring when connecting the transformers to the mains, a mathematical model of the transformer was developed, which was validated through tests (simulations, measurements) in order to determine the electrical stress of the transformer. The test was carried out on a 15 MVA, 10.5/6.3 kV transformer, starting from its magnetization parameter. The modeling of the phenomenon occurring when connecting the transformer to the supplying network was achieved using MATLAB software, and the results obtained thereof were similar to those obtained from laboratory experimental measurements.