動態電纜搭載於半潛式浮動平台之配置設計對於電纜負荷的影響

Abstract

因當今離岸風場建造趨勢往愈大的水深，浮動式平台之發展也愈加重要，海底動態電纜作為將風機所發之電力運送至海上變電站(offshore substation)的關鍵組件會有更大的需求，本研究主旨為比較四種不同的電纜配置方式在對於經歷不同海況後的受力影響。 本篇使用SIMA做為模擬軟體，以IEA 15MW浮式風機系統搭配66kV規格之電纜，並設計四種配置：惰波式(Lazy wave)、陡波式(Steep wave)、燈籠式(Chinese lantern)、懸垂式(Catenary)，在此四種不同的配置再各設計6種不同的長度，共計有24個電纜配置設計，於台灣合適風場的平均水深70 m水深為基礎，先以單一海況改變(純更動海流向、波高、流速、週期等)，對於這四種配置，我們觀察到它們在應對不同海況時，受力趨勢和適應程度均存在差異。 本論文使用合適值公式作為本篇研究對於電纜配置分析評斷的主要依據，此公式為計算電纜於海況中的受力及曲率與電纜本身的最大容許力之比值，以三種不同程度的海況大小且風波流同向0度的真實海況進行模擬，如常態海況、十年回歸週期海況以及五十年回歸週期海況。 總結來說為四種電纜配置方式在面對各種海況時，除了懸垂式配置全部皆失敗以外，其餘的電纜配置皆能承受本篇海況的設計，得出結論為惰波式配置的電纜長度設計需要長於160 m，且配置外型需呈現較大的曲率半徑；陡波式配置則是電纜長度愈短，合適值愈好；燈籠式配置的電纜長度至少要58 m。此外，本研究呈現的結果為不同的電纜配置在不同的海況下的合適值排序皆有所不同，但在符合50年回歸週期海況的情況下，結果可以得出在燈籠式配置設計會是最適合應用在 70 m水深的電纜配置方式，其次的配置則是陡波式，最後亦可以應用於風場中但較沒那麼優良的配置為惰波式。 本研究的結果對於離岸風機浮式平台的電纜配置設計提供了許多的參考，可以了解到電纜配置的受力後曲線趨勢，以及不同配置之間的差異性和海況改變對於電纜受力的影響，對於未來的相關研究提供了基礎的參考。

As offshore wind farms continue to venture into deeper waters, the development of floating offshore wind turbine (FOWT) has become increasingly important. The dynamic power cable, a critical component of FOWT, functions to transmit power to offshore substations. This research utilizes SIMA as the simulation and analysis software, focusing on the 66kV dynamic power cable used with the IEA 15MW FOWT. We assessed four types of cable configurations: Lazy Wave (LW), Steep Wave (SW), Chinese Lantern (CL) and Catenary (C). For each configuration type, we designed six different lengths, creating a total of 24 unique cable configuration shapes for evaluation. This research takes the maximum axial force and maximum curvature of the cable as the reference basis. First, we conducted parametric sensitivity study to observe the cable load change, where variable changes such as current direction, wave period wave height and current speed alone was adjusted one at a time to assess the different configurations. Next, we analyze these configurations under three specific sea state conditions: normal, 10-year return gust, and 50-year return gust, using the Fitness function. This function is calculating the sum of two ratios: the cable's axial force to its minimum breaking load, and the cable's curvature to its maximum allowable curvature, under these sea states. Among the four cable configurations, all except the C could withstand these sea states. The results are as follows: the LW required a cable length over 160 m, the SW performed better with a shorter cable length and the CL required a minimum cable length of 58m. Moreover, based on the simulated results of the 50-year return gust sea states, the CL configuration was found to be the most suitable for cable configurations at a water depth of 70 m. The next most suitable configuration is the SW. Lastly, while not as optimal, the LW configuration could still be used in wind farms. Overall, this study provide references for the designing of cable configuration for FOWT. It presents the differences between various cable configurations and the effect of sea state changes on the cable loads, paving the way for future research in this field.