Power System Analysis

CHAPTER 7

Short-Circuit Analysis—2 (Unbalanced Fault Analysis)

7.1 Introduction

If the fault involves only one or two of the three possible phases, then the fault is said to be an unbalanced or asymmetrical fault. Due to these faults, the system loses symmetry or balanced condition. Fault calculations can be easily performed by the use of a tool known as the “symmetrical component”. Using these components unbalanced vectors can be transformed into balanced vectors, through which calculations can be performed on a single-phase basis. This makes calculations easier as seen in the case of symmetrical fault analysis.

7.2 Symmetrical Components

In the year 1918, French mathematician Fortescue proposed a mathematical tool known as “symmetrical components ...