風場併入系統衝擊之改善及控制策略

Improvement of the Impact in Wind Farm Connection to Distribution Network and Control Strategy

陳立杰(Li-Chieh Chen)

指導教授 ： 李清吟

國立臺北科技大學/電資學院/電機工程系所/碩士(2008年)

摘要

世界各國正大力推行再生能源發電，風力發電為再生能源中最普遍且為目前發展重點之發電方式，因為台灣西部沿海風力資源豐富，每年固定的季風期，加上高山及離島地區風力的蘊藏量相當豐富，所以發展風力是不錯的選擇，因此陸陸續續完成風場之建置。當併入市電的風場容量愈趨增加時，將會給系統和客戶帶來新的可能性以及問題，針對風場的併入狀況和影響去計算和分析，特別當風機併接在較偏遠的地區是首要考慮方向，因為其衝擊將會更加嚴重。這個考量主要是因為風機大多配置感應式發電機，必須從系統端吸取大量的虛功率，而這可能導致低電壓以及電壓穩定度的問題產生，特別是饋線端有較大變動性負載時，提前針對其所可能造成的衝擊進行研究探討，找出解決之道，藉以提供較高的系統穩定度。
本文採用軟體MATLAB/Simulink為分析工具，及其內建之非同步機模型，研究首先從小型系統著手，最後再選擇台電二期風力計畫中之雲林麥寮實際風場進行模擬，過程中以鼠籠式和雙饋式兩種形式的風機併入系統來進行模擬，包括風機併網、併聯位置選取、故障電流分析和動暫態響應，以瞭解當大型風場併網對系統的衝擊與系統故障時對風機的影響。
定速型風機是採用SCIG型式，機組容量為1.5 MW，探討風機併網位置及數量不同情況下，在併網瞬間和風速變動期間對系統所造成的影響，此類型風機沒有變速的功能，雖然風機的技術已經有了明顯的進步，但大部分的風機仍然是使用感應式發電機，由於感應式發電機無法進行電壓的調整，且必須從系統端吸收所需的虛功率，這通常是電壓擾動的來源。因此探討定速型風機所引起的電壓不穩定問題以及利用彈性交流輸電系統（Flexible AC Transmission System, FACTS）來改善其動態響應，在系統中加入SVC和STATCOM，由模擬結果可以得知，風機在併網瞬間和風速變動期間對系統的影響，確實可以有明顯的改善，尤其對於風機併接於饋線末端的狀況下，其效果比原本系統優異許多。
變速型風機是採用DFIG型式，機組容量為2MW，使用台電二期風力計畫中之雲林麥寮實際風場作為系統，探討併網瞬間和風速變動期間所造成的影響，由於此類型風機具有變速的功能，且可以對系統提供虛功率，因此能夠對電壓和功率因數進行調整，分析雙饋式風機在虛功率控制和電壓控制操作模式下系統的響應情況，找出較佳的控制方法。

關鍵字

再生能源 ； 風力發電 ； 系統衝擊 ； 彈性交流輸電系統

並列摘要

The renewable energy is urged on promotion by the Countries in the world, and the wind power is the most common and development priorities now. Because there are plenty of wind at the coast of Western Taiwan, every year during monsoon period the reserved of wind at high mointains and off-shore is very sufficient. Developing the wind generation is a good choice and many wind farms are constructed continuously. Increasing capacity of connected wind power generation to utilities brings new opportunities and also problems to the utilities and customers. Evolution and analyzing of the connection conditions and effects of wind farms especially on remote areas are the main aspects of developing wind power on the utilities, because the impact will be more serious. The problem is that these wind turbine that mostly uses induction generators, tend to drain large amounts of VARs from the grid, potentially causing low voltage and maybe voltage stability problems for the utility owner, especially in the case of large load variation on distribution feeder. Focus on researching and discussing the impact ahead of time, and find the way out to supply higher degree of system stability.
This thesis chooses as analyzing tool by Matlab/Simulink, and uses the model of Asynchronous Generator. This research commences on a smaller power system first, and selects the wind farm at Yunlin Mailiao of the second issue of the TPC’s projects of wind power to simulate. Simulation as wind turbines using type of SCIG and DFIG connected to the system, including interconnection of wind turbines, location of wind turbines, fault current analyzation, dynamic and transient phenomena. To understand the impact as interconnection of the large wind farms and the influence of wind turbines during the fault.
Fixed speed wind generator using type of SCIG, the capacity is 1.5 MW, to discuss the influence of the system due to the moment of the wind generator connected and period of the wind speed variation, while the locations and numbers of wind generators connected are different. This type of wind generator doesn’t perform variable speed, even though there is significant progress in the wind generation technology, most of the wind turbines utilize induction generators a produce the electricity. Since the induction generators do not perform voltage regulation and absorb reactive power from the utility grid, they are often the source of voltage fluctuations. Therefore, discussing about the situation as voltage unstable due to large wind farms interconnected, and using FACTS in order to improve the dynamic response. We can know by the simulation result, the influence of system caused by the moment of the wind generator connected and during the wind speed variation can be improved emphatically while adding SVC and STATCOM in the system. The effect is much better than the original system especially while wind generators interconnected at the end of the feeder.
Variable speed wind generator using type of DFIG, the capacity is 2 MW, the system using the wind farm at Yunlin Mailiao of the second issue of the TPC’s projects of wind power. To discuss the influence of the system due to the moment of the wind generator connected and during the wind speed variation, this type of wind generator can perform variable speed and supply the reactive power to the system. The voltage and power factor could be adjusted by DFIG. In addition, analyzing the response of the system by DFIG using operation mode of Var and voltage control, therefore find the better way out.

並列關鍵字

Renewable Energy ； Wind Generation ； System Impact ； FACTS

參考文獻

[4] 王醴、林育宏、張哲豪，「風力用感應發電機之負載潮流分析」，中華民國第二十六屆電力工程研討會論文集，桃園，2005，第609-613頁。

[11] 王醴、劉志勇，「多部用風力感應發電機之動態模擬與分析」，中華民國第二十六屆電力工程研討會論文集，桃園，2005，第604-608頁。

[12] 王醴、黃偉、陳贊家，「靜態同步補償器應用於風場之特性分析」，中華民國第二十八屆電力工程研討會論文集，高雄，2007，第D1.4-1-6頁。

[13] 王醴、黃偉、陳贊家，「靜態虛功補償器應用於風場之特性分析」，中華民國第二十八屆電力工程研討會論文集，高雄，2007，第D1.1-1-5頁。

[14] C. Chompoo-Inwai, W. J. Lee, P. Fuangfoo, M. Williams and J. R. Liao, “System impact study for the interconnection of wind generation and utility system,” IEEE Transactions on Industry Applications, Vol. 41, Issue 1, Jan.-Feb., 2005, pp. 163-168.