On The Excitation Speeds of Capacitor-Excited Stand-Alone Induction Generator

Abstract

The principle of self-excitation, by which an induction generator can be excited by means of static capacitors connected across the machine terminals, has long been known. Although this fact was realized back in the thirties, it is only during the last few decades that the subject of the induction generator has received considerable attention. The reason is the growing emphasis on alternative energy sources, and the need for a suitable electric generator to match the requirement of operational simplicity and cost effectiveness. Although the induction generator has already emerged as an alternative choice to the synchronous generator in such areas as stand-alone wind energy farms and remote hydro-electric applications, research efforts are still directed to the understanding of self-excitation boundaries of the stand-alone unit. It is generally believed that better insight into the generation requirements of a given machine will afford the cost optimization target. The work to be presented in this thesis is concerned with the self excitation boundaries of a given machine. The experimental observations conducted show the possible existence of a pre-nominal self-excitation speed if the machine is driven at a lowerramp rate with capacitors permanently connected. It is suggested that with the availability of user-friendly program packages such as Mathlab, algorithms for the solution of system non-linear equations could be developed for the prediction of self-excitation capacitors and speeds.