TITLE:
Investigating the Effects of Slack Bus Selection in Load Flow Studies: A Comparative Analysis of Robust and Weak Grids
AUTHORS:
Nutifafa K. Fiasorgbor
KEYWORDS:
Load Flow, Slack Bus, System Losses, Voltage Stability
JOURNAL NAME:
Journal of Power and Energy Engineering,
Vol.11 No.9,
September
7,
2023
ABSTRACT: Load flow studies play a critical role in the analysis of power systems.
They enable the computation of voltage, current, and power flows in a power
system. They provide valuable insights into the steady-state performance of the
power system under different operating conditions. Choosing a slack bus is a
vital step in conducting load flow simulations. A slack bus is a PV bus that
includes a generator and is used to balance real and reactive power during load
flow studies. Many studies have been conducted on the selection of slack buses
in load flow analysis. However, varied conclusions regarding the impact on
system losses and power flows were obtained during these studies. Therefore,
using the IEEE-14 bus test system, this study investigated the effects of slack
bus selection in strong and weak grids by alternating slack buses among PV
buses and observing the effects on bus voltage magnitude, bus voltage phase angle, total power flows, and active and
reactive power losses. The study noted that the effect of slack bus selection
on these system quantities is contingent upon the voltage stability of the
grid. Whereas in a robust grid, system losses and power flows remained constant
irrespective of the choice of slack bus, a weak grid experienced some
variations in these system quantities under similar circumstances. The
simulation results led to the conclusion that, to a large extent, the voltage
stability of the grid plays a significant role in determining the degree to
which slack bus selection affects system losses and other quantities in load
flow studies.