Stability Analysis of DFIG based Wind Energy System

Abstract

Abstract-This paper presents system stability analysis of DFIG based wind energy conversion system. Presently for variable wind speed DFIG is considered as efficient machine to generate the power. In addition to this advanced AC/DC/AC converters with closed loop control system has been presented. For stability analysis 1.5MW wind turbine has been considered. As the speed of the wind varies by ± 18% to 20% the voltage generated will also varies by ± 18 to 20%. With the aid of precise converter design it is possible to achieve stable output at the grid. From the simulation results it has been found that the method of achieving stable output at the grid is best suitable for wind energy conversion system. Keyword -Wind turbine, wind energy conversion system, power converters, closed loop system, doubly fed induction generator I. INTRODUCTIONWind energy is one of the major sustainable energy resources. Wind energy is clean and renewable. Wind energy conversion system makes use of modern power electronics knowledge and control [1]. Presently wind energy conversion has attracted worldwide attention for research and development. Therefore, the design of wind turbine is a very popular research area. The DC power produced by renewable energy has to be converted in to AC power by means of modern power electronics and control system. DC power can be converted in to AC power using inverters. Depending upon the mode of operation two types of inverters are required, namely (i) standalone mode inverter and (ii) grid connected inverter. Conversion efficiency is a significant factor for both the types of inverters.The advancement in technology in designing wind mill blades, wind turbine generators, power electronic converters, and thyristerized control system have provided fast growth for large scale wind power generation [2][3]. Modern Wind generators incorporate wide range speed control techniques such as blade pitch control or make use of power converters in order to control the output power of the wind turbine. The speed control technique of wind turbine and the grid integration of wind power system is of vital importance, which will be carried out by power electronic devices. Also since the wind speed is uncertain, the power quality and reliability of wind power needs detail evaluation with suitable control schemes. The rapid growth in large scale wind power has made researchers to develop low cost power converters with high power density and reliability. This paper presents modern power converter technology of high power density and reliability as required by the wind energy conversion system.