STATCOM BASED VOLTAGE REGULATOR FOR SELF-EXCITED INDUCTION GENERATOR

Abstract

Self-Excitation process in induction generators is a complex physical phenomenon, which has been studied extensively in the past. The interest in this topic is sustained primarily due to application of self-excited induction generators (SEIG) in isolated power systems. Owing to the changed emphasis on energy problems, the development of suitable low cost isolated power generators, driven by renewable energy sources such as wind, biogas, etc is indeed a promising alternative. The terminal reactive power support in case of isolated generator is required to be adjustable so that the proper amount of reactive power can be supplied under different operating conditions. Consequently, a. controllable terminal voltage for the self-excited generator can be obtained through an appropriate control scheme. To fulfill the objective of varying the equivalent capacitance connected to the generator terminal continuously; some power electronic circuits need to be introduced into such a system. The self-excited induction generator is analyzed using the generalized-machine theory transient representation of the machine. Such an analysis produces instantaneous currents, which can be used to investigate the process of current and voltage build up during self-excitation and similarly perturbations due to load changes. In this dissertation work the transient analysis of self-excited induction generator is carried out. The instantaneous values of direct and quadrature axis stator and rotor currents and voltages for different load currents are found by solving differential equations representing the dynamic behaviour of the machine. This includes the building up of voltage during the initiation stage of self-excitation and the perturbations of the terminal voltage and the stator current, which result from load changes..