الفهرس 
Chapter 1 INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Electrical energy is one of the crucial inputs for social-economic development. The rate at which the electrical energy is being consumed by a nation often reflects the level of prosperity that it could achieve. Due to finite of the fossil fuels, the environmental pollutions and the increasing of the energy demand day by day, the utilization of the renewable energy are imperative necessity. Among the renewable power sources, wind power has recently experienced a rapid growth
around the world, and it is on track to supply 10-12% of global electricity demand by 2020.
Commercially available wind generators installed, at present, can be split, in
general, into two types fixed speed wind turbine equipped with squirrel cage
induction generators, and variable speed wind turbine equipped with wound field synchronous generator or permanent magnet synchronous generator or doubly fed induction generator, which is more advantageous and it is widely used.
It is known that, dynamic performance of the wind turbine generators is
differing from that of the conventional synchronous generator either from the
generator types or from the input mechanical power nature. Therefore the impact of the wind farm on the power system stability is differing from that of the synchronous generators. However, in spite of the well coverage of stability issues in conventional power systems, no sufficient analysis is carried out for recognizing the power system stability issues when large wind farms are interconnected with the system grid. This highlights the importance of the present research, which recognizes the essence of the power system stability problem when large amounts of wind power are penetrated into its grid.
The aim of this thesis is to investigate, thoroughly, the impact of largeintegrated
wind farms on power system angle, frequency and voltage stability.
Firstly, 5-machine, 16-bus power system is considered and it is assumed that one of
its synchronous generators is replaced by either a fixed-speed induction generator or a doubly-fed induction generator. Next, the dynamic models for the system synchronous generators and wind farms generators are introduced in details. All scenarios that may affect the power system stability are introduced. It is found that connection of the fixed-speed induction generator with a power system can affect remarkably its voltage stability. Also, considering the doubly-fed induction generator, longer critical clearing times are permissible.
Furthermore, the doubly-fed induction generator crowbar and chopper rotor
protection schemes can be used for improving the system voltage stability,
increasing the penetrated wind power value, and supporting the generator reactive power capability.