Voltage drop calculation considering transformer inrush current with EDG operation

A purpose of voltage drop calculation is to evaluate the dynamic capability of the EDG for loading steps. This calculation is intended to carry out a simulation in the most severe emergency diesel generator loading sequence condition. It is important to ensure that EDGs operate safely and consistently. For this reason voltage drop calculation is necessary at the planning and conceptual design stage of the project. ETAP, which can simulate the dynamic characteristic of emergency diesel generator, has been commonly used in this study. Normally, ETAP is difficult to consider the transformer inrush current for voltage drop calculation. It brings out inaccuracy of simulation, and leads to decrease reliability of the calculation. This paper suggests a transformer inrush current modeling method in consideration of loading sequence.