Abstract:
The purpose of the study presented in this thesis was to analyse the impact of DG on
voltage stability of a standard IEEE 9-busnetwork, using one of the static methods, the PV
and QV curves.
In a first step, this study defined the DG, the type of DG and it’s structures, the electric
grid and the different ways of connecting DG to the electric grid.
In a second step, this study defined the stability of electrical networks, exposed the
different types of this stability, voltage instability and its causes and the methods of voltage
stability analysis. Finally the impact of DG on voltage stability and power system in general.
In the third step, this study allowed the power flow to be performed ,PV and QV
curves to be plotted, allowing a static voltage stability analysis.
Finally ,a voltage stability analysis of a standard IEEE9-bus network was performed
using the PV and QV curves analysis.
From these curves, the influence of the power factor on the voltage stability can also be
seen .When the power factor changes from an inductive load to a capacitive load, the power
transmitted through the line increases, the voltage drop decreases and the reactive power
decreases, that means the stability margin increases.
This study allowed us to identify the weakest bus of the network so that necessary
measures can be taken to prevent a black out in a power system.
Concerning the impacts of DG on the voltage stability of power systems, the
following conclusions are drawn:
In general the integration of DG improves the voltage stability of the distribution
system.
The Location of the DG has main effect on voltage stability.
PV and QV curves are two simple approaches to find the critical voltage point and the
stability margin when the system is in a steady state
