Ground Current Analysis during Steady State and Transients in Power System

The paper deals with the analysis of the current flowing through the transformer neutral, where the current is detected by the ground overcurrent protection in the normal operating state during routinely switching-off operations in the power system. The inspiration of stated issue was a real event in the operation of the power system when the overcurrent protection in the neutral of the generator transformer in the power plant operated. The reaction of the overcurrent protection was in accordance with its setting, but it responded to a normal situation in the transmission system, the disconnection of the transmission line, but not to a fault.