本論文使用變頻變壓器連接兩電網，以形成微電網傳輸介面基本架構，此兩電網分別為台電電網以及使用自激式感應發電機建立之微電網，進而研究變頻變壓器於此系統之電力潮流、穩態以及動態響應結果。
本論文係以繞線型轉子感應機作為變頻變壓器之核心，搭配感應驅動馬達、驅動馬達控制器以及補償電容器作為變頻變壓器之架構，藉此完成兩種不同模式下之控制以及各種干擾下系統之變動情形。兩種控制模式分別為手動控制模式以及自動控制模式：在手動控制模式下，系統針對使用者輸入之實功率參考值進行功率傳送；在自動模式下，系統針對電網頻率的變化，自動調整傳送實功率之大小以及流動方向。在模擬方面，本文以三相平衡系統之交直軸等效電路建立其模型，模擬系統於時域以及頻域下之電氣特性，以驗證本系統之可行性。

The aim of this thesis is to use a variable frequency transformer (VFT) as a microgrid connection interface (MCI) to connect two grids. The two grids are the Taipower grid and a microgrid that includes a self-excited induction generator (SEIG) and a local load.
The core of the proposed VFT is a wound-rotor induction motor driven by a squirrel-cage induction motor while both sides of the VFT are connecting with compensation capacitors. Two operation modes, the manual mode and the automatic mode, are employed to control the active power flow of the two grids. When the system is operated under the manual mode, the VFT can control the transferred active power according to the active power reference. When the system is operated under the automatic mode, the VFT can automatically regulate the quantity and the direction of the active power according to the variation of the rotor-side frequency. The q-d axis equivalent-circuit model is employed to establish the model for the studied power grids with the VFT. This thesis also simulates the electrical characteristics of the VFT under time-domain and frequency-domain to demonstrate the advantages of the proposed VFT for controlling active power flow between two grids.

[1]R. Majumder, B. Chaudhuri, A. Ghosh, R. Majumder, G. Ledwich, and F. Zare, “Improvement of stability and load sharing in an autonomous microgrid using supplementary droop control loop,” IEEE Trans. Power Systems, vol. 25, no. 2, pp. 796-808, May 2010.
[2]A. L. Dimeas and N. D. Hatziargyriou, “Operation of a multiagent system for microgrid control,” IEEE Trans. Power Systems, vol. 20, no. 3, pp. 1447-1455, August 2005.
[3]P. J. Binduhewa, M. Barnes, and A. Renfrew, “Standard microsource interface for a microgrid,” in Proc. 2008 IET - CIRED seminar: Smartgrids for Distribution, no. 13, pp. 1-4, June 23-24, 2008, Frankfurt, Germany.
[4]GE Energy. Variable Frequency Transformer. [Online]. Available: http://www.gepower.com/prod_serv/products/transformers_vft/en/variable_frequency.htm, retrieved date: June 3, 2010.
[5]R. J. Piwko, E. V. Larsen, and C. A. Wegner, “Variable frequency transformer - A new alternative for asynchronous power transfer,” in Proc. 2005 IEEE Power Engineering Society Inaugural Conference and Exposition in Africa, pp. 393-398, July 11-15, 2005, Durban, South Africa.
[6]P. Li, P. Degobert, B. Robyns, and B. Francois, “Implementation of interactivity across a resilient microgrid for power supply and exchange with an active distribution network,” in Proc. 2008 IET - CIRED seminar: Smartgrids for Distribution, no. 111, pp. 1-4, June 23-24, 2008, Frankfurt, Germany.
[7]M. Barnes and P. Binduhewa, “Asynchronous interconnection of a microgrid,” in Proc. 2008 IET - CIRED seminar: Smartgrids for Distribution, no. 16, pp. 1-4, June 23-24, 2008, Frankfurt, Germany.
[8]S. Bala and G. Venkataramanan, “Autonomous power electronic interfaces between microgrids,” in Proc. 2009 IEEE Energy Conversion Congress and Exposition, pp. 3003-3013, September 20-24, 2009, San Jose, Canada.
[9]Y. W. Li and C.-N. Kao, “An accurate power control strategy for power-electronics-interfaced distributed generation units operating in a low-voltage multibus microgrid,” IEEE Trans. Power Electronics, vol. 24, no. 12, pp. 2977-2988, December 2009.
[10]V. Calderaro, V. Coppola, V. Galdi, and P. Siano, “Assessing control and management issues for micro wind generation integration into microgrids,” in Proc. 2008 IEEE Mediterranean Electrotechnical Conference, pp. 750-755, May 5-7, 2008, Ajaccio.
[11]G. Chen and X. Zhou, “Digital simulation of variable frequency transformers for asynchronous interconnection in power system,” in Proc. IEEE PES 2005 Transmission and Distribution Conference and Exhibition: Asia and Pacific, August 14-18, 2005, Dalian, China.
[12]A. Merkhouf, S. Uphadayay, and P. Doyon, “Variable frequency transformer electromagnetic design concept,” in Proc. 2007 IEEE Power Engineering Society General Meeting, June 24-28, 2007, Tampa, Florida, USA.
[13]J. J. Marczewski, “VFT applications between grid control areas,” in Proc. 2007 IEEE Power Engineering Society General Meeting, June 24-28, 2007, Tampa, Florida, USA.
[14]E. R. Pratico, C. Wegner, E. V. Larsen, R. J. Piwko, D. R. Wallace, and D. Kidd, “VFT operational overview - The Laredo project,” in Proc. 2007 IEEE Power Engineering Society General Meeting, June 24-28, 2007, Tampa, Florida, USA.
[15]A. Merkhouf, P. Doyon, and S. Upadhyay, “Variable frequency transformer - Concept and electromagnetic design evaluation,” IEEE Trans. Energy Conversion, vol. 23, no. 4, pp. 989-996, December 2008.
[16]P. Marken, J. Roedel, D. Nadeau, D. Wallace, and H. Mongeau, “VFT maintenance and operating performance,” in Proc. 2008 IEEE Power and Energy Society General Meeting - Conversion and Delivery of Electrical Energy in the 21st Century, July 20-24, 2008, Pittsburgh, Pennsylvania, USA.
[17]R. Yuan, Y. Chen, G. Chen, and Y. Sheng, “Simulation model and characteristics of variable frequency transformers used for grid interconnection,” in Proc. 2009 IEEE Power and Energy Society General Meeting, July 26-30, 2009, Calgary, Canada.
[18]P. Hassink, P. E. Marken, R. O'Keefe, and G. R. Trevino, “Improving power system dynamic performance in Laredo, TX,” in Proc. 2008 T&D IEEE PES Transmission and Distribution Conference and Exposition, April 2-24, 2008, Chicago, Illinois, USA.
[19]P. E. Marken, J. J. Marczewski, R. D'Aquila, P. Hassink, J. H. Roedel, and R. L. Bodo, “VFT - A smart transmission technology that is compatible with the existing and future grid,” in Proc. 2009 IEEE Power Systems Conference and Exposition, March 15-18, 2009, Seattle, Washington, USA.
[20]P. M. Anderson and A. A. Fouad, Power System Control and Stability, Iowa: The Iowa State University Press, Ames, 1977.
[21]P. C. Krause, Analysis of Electric Machinery, New York: McGraw-Hill, 1986.
[22]P. Kundur, Power System Stability and Control, New York: McGraw-Hill, 1994.
[23]C. M. Ong, Dynamic Simulation of Electric Machinery, Pearson Education, 2005.
[24]H. Saadat, Power System Analysis, McGraw-Hill, 2002.
[25]瓦特轉換器使用手冊，晨邦科技有限公司，2010年2月22日。
[26]晨邦科技有限公司，頻率轉換器使用手冊，2010年2月22日。
[27]ICP DAS. WinCon-8000. [Online]. Available: http://www.icpdas. com/products/PAC/wincon-8000/introduction.htm, retrieved date: February 22, 2010.
[28]DELTA ELECTRONICS, INC. VFD-E Series. [Online]. Available: http://www.delta.com.tw/product/em/drive/ac_motor/ac_motor_product.asp?pid=1&cid=1&itid=8, retrieved date: February 22, 2010.
[29]林秉毅，市電並聯型感應發電機之沼氣發電系統應用分析，國立成功大學電機工程學系碩士論文，2002年5月。
[30]李東璟，以數位信號處理器完成風力用獨立自激式感應發電機可控整流器與切換自激電容器組之協調控制研究，李俊德，設計三相升壓電路與可控換流器於自激式感應發電機之研究，國立成功大學電機工程學系碩士論文，2004年6月。
[31]張哲豪，結合網際網路與可程式控制器於混合發電/儲能系統之遠端即時監控，國立成功大學電機工程學系碩士論文，2006年6月。
[32]李俊德，設計三相升壓電路與可控換流器於自激式感應發電機之研究，國立成功大學電機工程學系碩士論文，2008年6月。
[33]陳龍億，變頻變壓器連接於電力系統之功率潮流控制與穩定度分析，國立成功大學電機工程學系碩士論文，2009年6月。
[34]余國威，採用感應機之整合式啟動-發電系統研究，國立成功大學電機工程學系碩士論文，2009年6月。
[35]胡阿火，電機機械，全華圖書股份有限公司，2007年11月。
[36]施松村、陸茵、楊名全，VB.NET程式設計藝術，全華圖書股份有限公司，2004年10月。