الفهرس | Only 14 pages are availabe for public view |
Abstract During the last recent of research projects focused on the use and development of new systems utilizing alternative sources of energy. The work covered the use of induction machine in general and squirrel cage induction machine in particular, to act as a generator for such applications, depending upon the nature of prime-mover (constant speed or variable speed) operated from various renewable energy sources such as wind, small hydro heads, bio-gas ... etc. ,in isolated and remote locations. Due to its reduced unit cost, brushless rotor construction, absence separate source for excitation, ruggedness, ease of maintenance and self protection against severe overloads and short circuits, a self-excited induction generators (SEIG) has emerged as a suitable candidate of isolated power source This thesis presents an experimental and analytical investigation operating transient operation in balanced and unbalanced modes. It surveys the steady analysis of stand-alone self-excited induction generator, in balanced mode, including the description of the theory of self-excitation evaluation for the performance. It focuses on studying characteristics of unbalanced SEIG under transient operations a complete performance the following cases : * when two phase capacitors are disconnected (case one). * when one line is opened (case two). * when two phases are short-drcuited (case three). * when unbalanced excitation capacitor bank are connected across the stator winding of the SEIG (case four). It has been noted that the machine can build-up the voltage for all cases except case three (two phases are short-circuited) since the capacitor equal zero, and there will be no self-excitation for this case. The experimental results are very close to the digital computer simulation which shows the validity of the proposed techniques. |