| dc.description.abstract | The power systems today are becoming more larger, complex and are operating closer to their
security and stability limits particularly due to an increase in load demands and number
of environmental concerns. Voltage stability has been a major subject of discussion and
concern in electric power system operation and planning worldwide. Firstly, this thesis aims
to do the survey on voltage stability and collapse phenomena in order to get insights into
the mechanisms, causes, and prevention techniques to avoid such.
The dynamic long-term voltage stability analysis is carried out using a free and open source,
MATLAB based-PSAT software taking a test power system. The influence of load models,
overexcitation limiter and transformer load tap changers on voltage collapse are investigated
as a part of the thesis. It is observed that the constant power load has a greater impact
on the voltage instability as it tries to restore the load unlike constant impedance and the
constant current loads.
Furthermore, a mathematical model for drawing the generator PQ capability diagram is
presented and implemented in MATLAB software environment. For improved visualization
and user interactions, a visualization tool is developed using the Graphical User Interface.
In addition, the temperature development in the rotor and stator of the 103 MVA hydrogenerator at ‘Åbjøra’ in Norway, is investigated in the same visualization tool utilizing the
already developed thermal model.
For increased accuracy of the results from dynamic voltage analysis, development and use
of more accurate power system component models is recommended. Moreover, the effect
of changing armature voltage and the direct axis synchronous reactance on PQ capability
diagram can be investigated under further study. | en_US |
