Modelling and analysis of grid connected wind energy system

In this thesis, a grid-connected doubly-fed induction generator (DFIG) based wind energy system (WES) was designed and performance of the designed system at variable wind speed and fault ride-through (FRT) capability were analysed. Firstly, a PI controller was applied to the rotor-side converter (RSC) and grid-side converter (GSC) of the designed system and the designed system was analysed at variable wind speed. Then, the performance of the system was improved by adding a maximum power point tracking (MPPT) controller to the RSC. In addition, the FRT capability of the proposed system was investigated during symmetrical and asymmetrical voltage dips in the grid. By adding a crowbar protection circuit to the RSC, the system components were protected against overcurrent and overvoltage caused by voltage dips. In order to improve the switching time of the crowbar protection circuit, a fuzzy logic controller (FLC) was implemented to the crowbar protection circuit. In this way, the FRT capability of the WES was improved. Real wind data of Edremit/Balıkesir region was used as wind speed profile. The generator parameters of Nordex N90/2.5MW wind turbine model were used as the turbine model. As a result of the simulation, the generated power, DC bus voltage, response time, electromagnetic torque, grid current, crowbar current and terminal voltage results were obtained. Additionaly the results obtained from simulation were compared with related studies. The obtained results showed that the proposed system is valid, applicable, and reliable when compared to related studies from the viewpoint of performance under variable wind speeds and FRT capability of the system.