Low Voltage Ride Through Enhancement of Squirrel-Cage Induction Generators Using STATCOM

• Main Authors: Bo-Ming Su, 蘇柏銘
• Other Authors: Yuan-Yih Hsu
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/45042864369491530125

碩士 === 國立臺灣大學 === 電機工程學研究所 === 102 === With the booming industry, excessive emission of greenhouse gases causes global warming effect coupled with the emergence of fossil energy crisis, renewable energy has received much attention during the past two decades. Wind power has been promoted as the focus of the renewable energy development due to its low cost. Although the growing wind farm installations can provide more electric power, they may have serious impact on the grid if they are tripped as a fault happened in the grid. To alleviate the situation, utilities worldwide start formulating regulations on low voltage ride through (LVRT) which request wind power generators to maintain grid-connected for a specific period after fault in order to support the system to go through the fault period. In this thesis, the low voltage ride through regulation in the “Grid Code of Renewable Energy of Taiwan Power Company” is employed as the reference of the analysis of the dynamic responses of squirrel-cage induction generators (SCIGs) under fault. SCIGs have been extensively used in wind power generation as the result of their simple configuration, high reliability, and low maintenance cost compared to other types of wind generators. However, when a power system fault causes a sharp voltage sag at its terminal, the SCIG’s output electric torque and the real power output will be significantly diminished, and the rotor will accelerate dramatically owing to the energy unbalance in the generator. 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 static synchronous compensator (STATCOM) is designed to extend the grid-connected period of SCIGs during the fault by supplying SCIGs with the reactive power to raise the terminal voltage of SCIGs so that the generator speed is stabilized with the increasing real power output. The MATLAB/Simulink/SimPowerSystems simulation software is used to simulate the dynamic performance of grid-connected SCIGs. Simulation results indicate that SCIGs compensated by the proposed STATCOM have a higher terminal voltage and better LVRT capability when there is a three phase fault in the system.