LVRT Capability Improvement of a Grid-Connected Squirrel Cage Induction Generator by DVR

Autor: Yi-Lin Chuang, 莊一麟
Rok vydání: 2013
Druh dokumentu: 學位論文 ; thesis
Popis: 101
The increasing wind farm installations have forced utilities worldwide to develop new grid codes to integrate wind power generation into the grid. One of the highly related codes is the low voltage ride through (LVRT) capability of wind generators, which requests that wind turbines remain grid-connected and help support the system voltage following disturbances. Squirrel-cage induction generators (SCIGs) have been extensively used in wind power generation due to their simple configuration, reliability, and low maintenance cost compared to other types of wind generators. However, when a fault takes place in the power system, its terminal voltage tends to dip dramatically, which leads to the decrease in SCIG’s output electric torque and thus hinders SCIG from generating electric power. Since the real power exported to the grid is significantly reduced during the fault while the input mechanical power from the wind turbine remains almost constant, the generator will accelerate during the short circuit event to mechanically store the energy excess. As the generator speed rises to a certain limit, over-speed protection will be triggered to disconnect the wind turbine from the grid to protect it from being damaged. In this thesis, a dynamic voltage regulator (DVR) is designed to regulate the terminal voltage of a SCIG during system fault so that SCIG has a stable real power output. Since the generator speed is stable, grid connection of the wind turbine during system fault can be ensured. This thesis uses MATLAB/Simulink/SimPowerSystems simulation tool to simulate the dynamic performance of a grid-connected SCIG. Simulation results indicate that SCIG compensated by the proposed DVR has a regulated terminal voltage and exports steady real power when there is a three-phase fault. Through computer simulations, it is convinced that the SCIG with DVR is able to remain connected to the grid during system fault and the LVRT requirement imposed by Taiwan Power Company can therefore be met.
Databáze: Networked Digital Library of Theses & Dissertations
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