CONTROLLING FREQUENCY OF SELF-EXCITED INDUCTION GENERATOR USED IN AUTONOMOUS WIND-TURBINES BY MEANS OF TERMINAL-EXCITATION CAPACITANCE

Abstract

The mam objective of this master thesis is to stabilize the frequency of the self­ excited induction generator that is used in the isolated wind systems. Selt excitation is provided by an external reactive power source, that it may be either over-excited synchronous generator or capacitor banks. The proposed reactive power source in the thesis is the Static Var Compensator (SVC) that can provide variable leading current to the induction generator. This type of induction generator is called Self-Excited Induction Generator (SEIG)

The output frequency normally is not constant, it is influenced by three external factors, rotor speed n, load conditions Z1, and the terminal capacitance C. As rotor speed and/or load condition are changed, frequency changes. It was suggested at each value of rotor speed and load, there is one value of terminal capacitance which maintain frequency constant at the desired value. The analysis of this SEIG is being performed by using the Matlab7.3 software.

The first stage of the thesis is the analytical study of the SEIG by using two non-linear equations, and the resultant curves are shown in the thesis, and then evaluating the value of terminal capacitance at which the frequency remains constant. The second phase of the thesis is the experimental work. The last stage is to simulate the project, and then matching between all results.