CONTROL OF DOUBLY FED INDUCTION GENERATOR COUPLED WITH WIND TURBINE

Abstract

The use of renewable sources has increased in the recent years because of the economical and ecological problems associated with the use of conventional energy resources. Among the alternate energy resources like solar, small hydro, wind, tidal, biomass and geothermal, wind energy is preferable due to its reduced cost and improved reliability. In the world, India is at 51h rank after China, USA, Germany, and Spain in installed capacity of grid connected wind power. Due to variable nature of wind, doubly fed induction generator based wind energy conversion system provides many advantages such as increased energy output, improved capacity utilization factor and reduced cost of generation as compared to fixed speed generation. In this dissertation work, a control strategy has been developed for DFIG coupled with wind turbine. For this purpose, modeling of various components of DFIG based WECS has been done and then complete model has been simulated under MATLAB environment. The wind energy system used is of 9 MW capacity and is connected to the grid of 132 kV via a 30 km long transmission line. For both rotor side and grid side converters, control strategies are presented. Pitch angle control is implemented to control power generated during gusts of wind. Performance of system is analyzed during voltage regulation and VAr regulation modes and it is found that voltage regulation, unity power factor operation, maximum power point tracking phenomena is satisfactorily observed under different disturbances such as voltage dip at grid terminals, wind speed variation, load variation, symmetrical and unsymmetrical ground faults.