A New Model for Correcting and Improving the Sequence Networks Method of
Single-Phase Earth Fault to Accommodate All Resistance Grounding Systems
- Yubo Wang
Abstract
The method of sequence networks is still well-known and widely utilized
for analyzing and computing unsymmetrical faults in power system
networks today, particularly in solid grounding systems where it was
initially introduced for short circuit analysis. When it comes to
single-phase earth fault that is a dominant majority type of fault in
power distribution grids, different neutral grounding methods with
varied impedances result in distinct fault characteristics, to continue
utilizing sequence networks could cause inaccurate calculations by the
reason of neutral voltage during earth fault does not remain as close to
zero as it's pinned in solid grounding system. As neutral resistance
increases gradually, the impact of line-to-ground capacitance becomes
more pronounced and can no longer be ignored. In this case, applying
sequence networks could lead to calculated results that are far from the
actual situations in grids.
This paper discovers and proves an obscurely hidden defect of the
sequence network, while proposing a new and novel modeling to derive
comprehensive equations of fault calculations for all types of resistant
grounding systems, including solid grounding, low resistance grounding,
high resistance grounding, and ungrounded systems.