Effects of transformers' short-circuit voltages and short-circuit powers of the grid equivalent on short-circuit current.

Abstract

In power systems, the most dangerous condition in the electromagnetic transients is the short circuit. When short circuit occurs, circuit impedance falls, the current increases and the voltage drops. These changes cause dangerous consequences to the grid. So short circuit current calculations play an important role in choosing the apparatus, relay protection regulation and the operation mode of grid. This article proposes building a system of short-circuit curves depending on two major parameters related to the transformer and the power grid equivalent. These curves are valued for different types of short circuits and depend on transformer types and the scale of the grid equivalent in two topology networks proposed. Accordingly, a simple intuitive user interface in MATLAB-GUIDE is represented. With these short-circuit curves given, the short-circuit currents are used to analyze and select fault current limiter (FCL) devices in substations.