Investigation and Mitigation of Transformer Inrush Current during Black Start of an Independent Power Producer Plant

Salman Kahrobaee, Marcelo C. Algrain, Sohrab Asgarpoor

Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, USA.
Electric Power Division, Caterpillar, Inc., Peoria, USA.

DOI: 10.4236/epe.2013.51001                

Abstract

The energizing of large power transformers has long been considered a critical event in the operation of an electric power system. When a transformer is energized by the utility, a typical inrush current could be as high as ten times its rated current. This could cause many problems from mechanical stress on transformer windings to harmonics injection, and system protection malfunction. There have been numerous researches focusing on calculation and mitigation of the transformer inrush current. With the development of smart grid, distributed generation from independent power producers (IPPs) is growing rapidly. This paper investigates the inrush current due to black start of an IPP system with several parallel transformers, through a simulation model in DIgSILENT Power Factory software. The study demonstrates that a single genset is capable of energizing a group of transformers since the overall inrush current is slightly above the inrush of the transformer directly connected to the generator. In addition, a simple method is proposed to mitigate the inrush current of the transformers using an auxiliary transformer.

Keywords

Black Start; Distributed Generation; Inrush Current Mitigation; Independent Power Producer; Transformer Energizing

Conflicts of Interest

The authors declare no conflicts of interest.

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