利用靜態同步補償器改善鼠籠式感應發電機之低電壓穿越能力

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

蘇柏銘(Bo-Ming Su)

指導教授 ： 許源浴

國立臺灣大學/電機資訊學院/電機工程學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.11026

摘要

由於工業的蓬勃發展，溫室氣體排放過量造成全球氣候暖化，再加上石化能源危機的出現，使得再生能源的發展逐漸受到重視，其中因為風力發電具較佳的經濟效益，因此風力發電被視為推動再生能源的重點。雖然與日俱增的風力機組裝置容量，可以提供更多的電力，但若風力機組隨故障發生而跳脫，則將對與之併網的系統造成嚴重的衝擊。因此各國電力公司開始制定低電壓穿越規範，規定風機必須於系統發生故障時，維持特定的併網時間，以支持系統穿越故障。
本論文將以我國「台灣電力公司再生能源發電系統併聯技術要點」中的低電壓持續運轉規範做為參考依據，並分析鼠籠式感應發電機在故障發生時的動態響應。由於鼠籠式感應發電機構造簡單、可靠性高、維修成本較低，故廣泛被應用於風力發電機組，但是當系統發生故障時，導致其端電壓驟降，造成電磁轉矩衰減，使發電機在故障期間所吸收機械功率大於輸出之電功率，讓轉子轉速不斷增加，最後過速保護啟動使之與台電系統解聯。為了延長風機在系統故障發生時的持續併網時間，本論文利用靜態同步補償器進行純虛功補償，提供虛功給鼠籠式感應發電機，提升發電機端電壓，使發電機得以穩定輸出電功率，避免轉子過速而與台電系統解聯。
本論文以MATLAB/Simulink/SimPowerSystems軟體，建立併網之鼠籠式感應發電機模型，模擬結果顯示，當系統發生三相短路故障時，靜態同步補償器可穩定鼠籠式感應發電機端電壓，並提升風機低電壓持續運轉能力。

關鍵字

風能 ； 低電壓穿越 ； 鼠籠式感應發電機 ； 靜態同步補償器 ； 純虛功補償

並列摘要

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.

並列關鍵字

wind power ； low voltage ride through ； squirrel-cage induction generator ； static synchronous compensator ； reactive power compensation strategy

參考文獻

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