澎湖大型離岸風場及海纜併接架構下之系統衝擊改善研究

System Impact and Improvement Researches for Integrating Large-Scale Penghu Offshore Wind Farm and Taiwan-Penghu Submarine Cable

徐景河(Ging-He Shu 徐景河)

指導教授 ： 陳昭榮 ； 李清吟

國立臺北科技大學/電資學院/電機工程系所/碩士(2010年)

摘要

澎湖地區的風力資源為世界絕佳之一，未來台澎海底電纜舖設完成後，台電公司規劃於澎湖外海興建大型離岸風場，隨著風場容量逐趨增加，併入電網時對系統的影響亦逐漸增加，研究風場與系統間之相互衝擊已成為規劃大型風場前重要課題。
本論文使用PSS/E作為分析軟體工具，以2015年台澎海纜舖設完成後之台電系統作為研究標的，並以雙饋式感應發電機(容量3.6MW)為研究的風力機型，同時並假設澎湖離岸風場總裝置容量為200MW併入系統後，在澎湖當地離峰與尖峰負載需求各為47.2MW與89.2MW狀態下，除了可供應澎湖當地負載需求外，剩餘功率將可透過海底纜線送回台灣。
本文第一部分針對澎湖大型離岸風場併入系統後，進行各種穩態與暫態的模擬案例分析，其中亦包括電力潮流、併入點電壓變動、故障電流、風場切離、系統故障致使風場跳脫之臨界範圍、澎湖系統孤島運轉、系統暫態穩定度與故障臨界清除時間等對系統之間衝擊，以保障台灣與澎湖系統在台澎海底電纜連接架構下之供電可靠度。
本文第二部分依據模擬之衝擊結果，研擬多種不同改善策略以讓離岸風場對於系統衝擊降至最低。這些策略包括：加入低電壓穿越設備、增加離岸風場裝置容量、加入FACTS設備、尖山機組投入運轉、利用風場運轉控制模式及增加海底電纜阻抗等策略，經由模擬結果顯示均有效降低系統衝擊程度之效果。
由模擬結果顯示，若風場容量愈大或採用低電壓穿越能力愈強時，其對於系統暫態穩定度改善效果愈顯著。另外從模擬亦發現，當系統發生嚴重故障，系統的暫態衝擊無法有效抑制時，致使風場保護電驛動作導致風場解聯，可能對系統造成二度衝擊。故在本文模擬多種改善策略中，以加入具備虛功補償且運轉靈活度較高的STATCOM改善效果最佳，不僅改善系統暫態低電壓，對於風場低電壓穿越能力更具強化效果，並可協助系統迅速回復至穩定之狀態。最後，本文分析結果可供台電公司未來建置規劃澎湖大型風場時之參考，以避免風場併入系統時造成系統相關輸電設備超載及暫態不穩定之問題。

關鍵字

離岸風場 ； 雙饋式感應發電機 ； 低電壓穿越能力 ； 穩態模擬 ； 暫態模擬 ； 穩定度改善 ； 虛功率補償

並列摘要

The Penghu area in Taiwan boasts one of the world’s richest wind resources. Taiwan Power Co., Ltd. (Taipower) is planning to build a large-scale offshore wind farm in Penghu after the Taiwan-Penghu submarine cable system is completed in the future. As the rise in the wind farm’s capacity is bound to trigger corresponding increase in its influence on the power system, assessing the mutual impacts between the wind farm and the power system has become a highly crucial issue in large-scale wind farm planning.
The thesis, adopting PSS/E as the analysis software, finds its study subject in the Taipower system to which the Penghu offshore wind farm will be connected in 2015 after the completion of the Taiwan-Penghu submarine cable system. The large-scale offshore wind farm is assumed to sustain a capacity of 200MW and use double-fed induction generator (Capacity of 3.6MW) as the wind turbine. In addition to meeting the off-peak and peak loads (47.2MW and 89.2MW respectively) of Penghu, the wind farm can be expected to generate extra active power for transmission back to Taiwan through the submarine cable system.
The first part of this thesis aims at analyzing the steady- and transient-state features in various scenarios after the large-scale offshore wind farm is connected into the power system so as to ensure reliable power supply between the Taiwan and Penghu power systems connected by submarine cables. Major features under analysis include: power flow, PCC (Point of Common Coupling) voltage variation, fault current, wind farm cut out, location of the fault that causes the tripping of the offshore wind farm, islanding operation of the Penghu power system, system transient stability and critical clearing time.
The second part of this thesis aims at developing a variety of strategies to minimize the impacts of the offshore wind farm on the Penghu power system. Proposed strategies include: adding a LVRT (Low Voltage Ride Through) device, increasing the offshore wind farm capacity, adding FACTS (Flexible AC Transmission Systems) devices, incorporating Jiang-Shan plant, utilizing wind farm operation control mode, and increasing the impedance of the submarine cable impedance. Simulation results indicate that these strategies are effective in reducing the impacts of the wind farm on the power system.
Simulation results further suggest that a greater wind farm capacity or a stronger LVRT capability helps better improve the system’s transient stability. In addition, when experiencing serious faults, the system may fail to effectively suppress the transient impact. The failure in turn may activate the protection relays of the wind farm and disconnect it from the power system, resulting in further impacts on the system. Addressing the issue, the thesis has simulated various improvement strategies of which STATCOM (Static Synchronous Compensator) appears to be the best choice thanks to its ability to facilitate reactive power compensation and its operational flexibility. This strategy is capable of improving the system’s transient low-voltage, reinforcing the LVRT strength, and speeding up the system’s recovery to normal operation after the faults are removed. The thesis can thus be expected to provide Taipower with valuable reference in planning the development of its large-scale offshore wind farm in Penghu, especially in terms of avoiding overloading of transmission facilities and solving the problem of transient instability as the wind farm is connected into the existing power system.

並列關鍵字

Offshore Wind Farm ； Doubly-Fed Induction Generator (DFIG) ； Low Voltage Ride Through (LVRT) ； Steady State Simulation ； Transient State Simulation ； Stability Enhancement ； Reactive Power Compensation

參考文獻

[7] 吳瑞南、曾耀毅、張建國，「風力發電機之低電壓安渡特性研究」，台灣風能協會第二屆第二次會員大會暨台灣風能學術研討會論文集，台北，2009，第216-221頁。

[35] 魏堂宇，靜態同步補償器和電力系統穩定器對系統電壓及穩定度之影響，碩士論文，國立台灣大學電機工程研究所，台北，2005。

[6] 陳唯泰，考慮風力發電併入澎湖電力系統保護策略之研究，碩士論文，大同大學電機工程研究所，台北，2007。

[10] J. Momeau, C. Abbey and G. Joos, "Effect of Low Voltage Ride Through Technologies on Wind Farm," IEEE Conference on Electrical Power, Canada, 2007, pp. 56-61.

[11] A. Luna, P. Rodriguez, R. Teodorescu and F. Blaabjerg, "Low Voltage Ride Through Strategies for SCIG Wind Turbines in Distributed Power Generation System," IEEE Conference on Power Electronics Specialists, Rhodes, 2008, pp. 2333-2339.