Performance and Power Factor Improvement of Indirect Vector Controlled Cage Induction Generator in Wind Power Application

Abstract

Wind energy is one of the most important and promising source of renewable energy all over the world, mainly because it is considered to be nonpolluting and economically viable. At the same time there has been a rapid development of related wind energy technology. The control and estimation of wind energy conversion system constitute a vast subject and are more complex than those of dc drives. Induction generators with cage type rotors have been used extensively in wind power generation systems for the variable speed applications in a wide power range. Generally, variable speed wind energy conversion system with Induction generators require both wide operating range of speed and fast torque response, regardless of any disturbances and uncertainties (turbine torque variation, parameters variation and un-modeled dynamics). This leads to more advanced control methods to meet the real demand. The recent advances in the area of field-oriented control along with the rapid development and cost reduction of power electronics devices and microprocessors have made variable speed wind energy conversion system an economical alternative for wind power applications. The complexity of wind energy conversion system increases substantially if high performances are demanded. The main reasons for this complexity are the need of variable frequency, harmonically optimum converter power supplies, the complex dynamics of ac machines, machine parameter variations etc. Various control techniques have been developed in the recent days for the control of cage induction generators. In this work a hybrid controller is developed for performance improvement of a cage induction generator used for wind power applications. The wind power generation system employs an indirect vector controlled cage induction machine as the generator. The induction generator system is evaluated separately with conventional PI-controllers, fuzzy controllers, self tuned fuzzy controllers and hybrid controllers and the performances are compared for each case. Power factor of the overall system is improved through control of grid side converter. Control circuits for PWM converter inverter system are also fabricated and tested.