地下電纜線路實施高效率冷卻系統之研究

A research on high effective for cooling underground cables.

郭子豪(Tzu-Hao Kuo)

指導教授 ： 蔡尤溪

國立臺北科技大學/機電學院/能源與冷凍空調工程系碩士班/碩士(2013年)

https://doi.org/10.6841/NTUT.2013.00607

摘要

近年傳統高架輸配電轉入地下為一重要趨勢。目前台灣地區地下電纜工程多採用共同管道，散熱模式採用自然對流與強制通風。但自然對流散熱僅限於低輸電負載情況，強制通風又存在冷卻區間長度與效率問題；超高壓電纜地下化後洞道中電纜及環境溫度對供電的效率及安全可靠度均非常重要！
本研究論文針對超高壓345kV電纜之散熱，採創新罩殼式工法，不同於傳統洞道式工法直接將電纜布設於洞道內，改以鋁殼包覆三條電纜及兩組冷卻管材。因345kV高壓輸電散熱高達110W/m條，挑戰遠高於一般中低壓電纜。本研究成功建立電腦模型，用於分析四種電纜散熱量(100%、75%、50%、25%)、三種管材(Copper、HDPE、SS304)、不同冷卻管材位置以及不同電纜布設工法(罩殼式、洞道式)分析；並透過溫度趨勢圖、分別以冰水側、罩殼內空氣側及洞道內空氣側，以熱阻模型概念導入熱傳比例探討。根據結果發現，以設定入水溫度7℃、流量900LPM/罩殼、冷卻區間一公里情況下，50%輸電負載可達到常時電纜絕緣體溫度90℃安全要求，若輸電負荷高於50%，則須加強熱傳效果。罩殼式較傳統工法存在熱源就近處理、安全溫度掌握容易等優點，相信為往後地下化高壓輸電之重點。

關鍵字

地下電纜 ； 電纜洞道 ； 電纜散熱 ； 氣流模擬

並列摘要

Overhead power cable has been changing to underground tunnel transmission in recent years. The trend of underground cable is also happening in Taiwan. Heat dissipation can be carried by natural convection heat convection but limited to low power load conditions. Forced convection air cooling has a limit in operating tunnel length and also efficiency problems. Temperatures of the加全寫EHV cables and the underground tunnel environmental are important to the efficiency, safety and reliability of the power supply.
This research is for the cable and tunnel cooling for a 345kV EHV cable system. Unlike the convection construction method that cables are laid in the tunnel in open, aluminum enclosures that contain three cables and two cooling pipes are used. 345kV high voltage transmission can have heat dissipation rate up to 110W/m.wire, therefore cooling the cable is much more challenging than the lower voltage cables. This study successfully built a computer model to analyze the cooling for four levels of cable heat dissipation rate (100%, 75%, 50%, 25%). Three types of cooling pipe materials (Copper, HDPE, SS304), cooling pipe locations and different cable laying were analyzed. Comparison between the open cables and enclosed cables was studied. The variation of temperature with time was analyzed for the heat transfer ratio through chilled water, air in the aluminum enclosure and through the airflow in the tunnel. Results of analysis are given for chilled water temperature at 7 ℃ and flow rate of 900LPM per aluminum enclosure casing per kilometer tunnel length. The results show that the cable cladding can reach the safe operating temperature of 90 ℃ for 50% heat load. Heat transfer has to be enhanced for heat load of more than 50%. The enclosed cable method has the advantage of better and reliable heat transfer in comparison to the convectional open cables. The results in this study show the potential of this method of cooling high voltage underground power cables.

並列關鍵字

Underground Power Cables ； CFD ； Power Cables Cooling

參考文獻

[3] 「地下電纜線路實施高效率冷卻系統之研究」，台灣世曦工程顧問股份有限公司，101年度工程計畫書，2012。

[4] 陳慶豐，「超高壓電纜地下洞道冷卻氣流模擬分析」，能源與冷凍空調工程研究所碩士論文，國立台北科技大學，2005。

[10] 杜文祥，“地下電纜洞道內冰水管間接冷卻系統之性能研究”，國立台灣大學機械工程研究所碩士論文，民國95 年。

[18] “共同管道工程設計標準訂定之研究”，亞新工程顧問股份有限公司，民國87 年。

[8] D.E. Williams, “Natural and forced-cooling of HV underground cables: UK practice”, IEE PROC, Vol. 129, Pt. A, No.3, May 1982.