Abstract:
The development of a software application to plot protection coordination curves and
provide a distance to fault locator is presented in this paper. The purpose of the application is to aid
fault location in power systems. Incorrect tripping of protection relay and fault location on power
lines have a significant impact on power system performance. Often protection engineers and
technicians need to verify grading of protection relays and to locate faults on power lines. The
application developed will allow drawing of protection relay curves to observe coordination of relays.
It also has a fault locator for non-homogenous medium voltage networks in distribution which
estimates distance to fault given the network topology and measured fault current. The application
was developed on Microsoft Excel® using the Visual Basic programming language. This will allow
the application to be run on any device supporting Excel, originally planned to run on a smart phone,
thus making the software easily accessible. The application allows up to four relay curves to be drawn
with a variety of curve types to choose from. The fault locator allows up to four conductor types to be
used in the network topology to accurately model the fault path. The fault locator was tested with data
obtained from two medium voltage overhead lines and gave satisfactory results.
