2024年高压直流海底电缆状态感知技术报告

Yanpeng Hao郝艳捧 CONTENTS Current rating calculation Buried depth detection Vortex-induced vibration detection 4 Conclusionandoutlook 5 1、 Background High-voltagedirect current(HVDC)submarinecables arethekey equipment to realizetheultra-large-scaleoffshorewindpowerlong-distancepowertransmission,withlonglength,highvoltagelevel.高压直流海底电缆是实现超大规模海上风电远距离送电的关键设备，长度长、电压等级高。 Crosslinked polyethylene(XLPE)is widelyused inthe insulationof HVDC submarinecables because ofits highreplacedoil-filledcables交联聚乙烯因耐高温、低损耗、易安装、电气性能与机械性能良好等优点而广泛应用于高压直流海底电缆，逐渐取代了充油电缆。 1、 Background The laying of submarine cables in the complex and changeable ocean always faces the risk of failure, includingnaturalcausesand man-madeinjuries海底电缆敷设在复杂多变的海洋中，时刻面临自然、人为损伤等风险。 At a certain depthbelowthe seabed,the upper seabed ofthe submarine cable is washed by ocean currents for a longtime, and may be exposed or even suspended.Its buried depth and exposed state are constantly changing,andvorticity induced vibration occurs in severe cases, easyto experiencewear and tear,mechanical fatigue.埋在海床下一定深度的海底电缆上部海床被洋流长期冲刷，埋深、裸露、悬空等状态不断变化，严重时发生涡激振动，易出现磨损、机械疲劳等情况Oncethe submarinecablefails,thecentralizedtransmission oftheentirewind farmwillbe stopped,and therepaircyclewilltake severalmonths.Thetechnical difficultyishighandthecostis extremely expensive.一且海底电缆故障，将停止整个风电场的集中送出，修复周期数月，技术难度大，成本极其昂贵。 Background GuangdongPowerGridplanstobuild a±500kVDC submarine cablein2025,witha single-polelengthof nolessthan100km. 广东电网拟于2025年建设1回土500kV直流海缆，单极长度不少于100km。 Shantou OffshoreWind Power Co., Ltd.,CR power has begun to build a ±5oo kV DC submarine cable project,whichisamilestoneprojectinthehistoryofglobaloffshorewindpowerdevelopment华润电力控股有限公司汕头海上风电电力有限公司已开始建设一回土500kV直流海缆工程。 Asubmarinecompositepowercableiswithopticfibers光纤复合海底电缆 500kVXLPEDCsubmarine cable500kVXLPE直流海底电缆 35kVXLPEACsubmarine cable35kVXLPE交流海底电缆 500kVOil-filledACsubmarine cable500kV充油交流海底电缆 150kV交流平滑铝套陆地电缆 Background Among the sensingtechnology,distributed optical fiber sensing technologyis the most suitablefor submarine cablestatedetection,Butthereisalackofappliedbasicresearch现有海底电缆状态检测技术中，分布式光纤传感技术最具优势。 1、Background The distributed optical fiber sensing hardware technology of submarine cable can meet the engineering requirements,butthebasiciesearchofstateassessmentapplicationisstilllacking海底电缆分布式光纤传感硬件技术已能满足工程要求，尚缺乏状态评估应用基础研究 Current status ofoptical fiber sensing technologyfor submarine cables海底电缆光纤传感技术现状 1、 Background The research ofDC submarine cable focuses on current rating calculation, temperature field calculation, burieddepthdetection and vortex-induced vibration detection直流海底电缆的研究集中在载流量计算、温度场计算、埋深检测与涡激振动检测等方面。 Vortex-inducedvibration涡激振动 Temperaturefield温度场 Buried depth埋深 Current rating载流量 Lackof detectiontechnology缺乏检测方法Cylinder and overhangpipe simulation, notcable insulationstructure圆柱体和悬跨管道仿真，不是电缆绝缘结构The fiber response isunclear光纤响应不明确 Lack of continuousdetection technology缺乏连续检测方法The depth of burieddepth detection islimited埋深检测的深度受限Lack ofenvironmental data缺少环境数据 21Current rating calculation Based on IEC 60287,the calculation ofcurrent rating of AC cables takes into account skin effects factor, proximityeffectsfactor,circulationlossesandeddycurrentlossescomparedtoDCcables.基于IEC60287，相比直流电缆，交流电缆载流量损耗计算考虑集肤效应因数Ys，邻近效应因数Yp，环流损耗2”和涡流损耗2 等 AC cable交流电缆 DC cable直流电缆 Jouleheatlossofaconductor导体的焦耳热损耗W.=IRInsulation dielectric loss :绝缘介质损耗：W,=ocU.tansLossfactorforsheathandscreen金属套与屏蔽损耗：,=,+Loss faclor for armour :铠装层损耗：12.77 R)° + 1V Current-carrying calculation:载流量计算：(0, Q)W0.5T, +n(T, +T, +T)V RT, +nR(1+ 2)T, + nR(1+ + 2)(T, +T) Accuratethermalpathcalculationmodel ofACsubmarinecable交流海缆等效热路模型 2. Current rating calculation Under AC voltage,theelectric field of insulation is capacitivedistribution,and the permittivity of thematerial isconstant.UnderDC voltage,the electricfield ofsubmarinecableinsulationis resistive distribution,and theconductivity of the materialisaffected byfield strength and temperature,which is a multi-physical field strengthcouplingofelectric-heat-flow.交流电压下，绝缘的电场呈容性分布，且材料的电容率是常数；直流电压下，海底电缆绝缘的电场呈阻性分布，且材料的电导率受场强、温度影响， 是电-热-流多物理场强耦合。 TheACCurrentratingcorrespondstothesteady-stateoperatingcurrentatthecoretemperatureof9ooC.TheDCCurrentratingconsidersnotonlythecoretemperaturebutalsotheaccumulationofspacecharge.ThemaximumtemperaturedifferencebetweenXLPEinsulationand siliconerubberinsulationislessthan2ooC. 交流载流量对应线芯温度90°C的稳态工作电流，直流载流量除考虑线芯温度外，还考虑空间电荷的积聚，XLPE绝缘、硅橡胶绝缘最大温差<20°C。 Calculation of current rating of DCsubmarinecable (lEC60287)直流海底电缆载流量计算（正C60287） 21Carrying capacity calculation When thetemperature difference of the cable insulation is greater than 2ooC, the electric field distribution will bereversed significantly.The position of the maximum electric field changes fromthe inner shield to the outer shield.电缆绝缘层温差大于20℃C时，电场分布发生显著反转。电场最大值位置由绝缘内屏蔽层变为外屏蔽层。 TheinsulationtemperaturedifferenceofDC cableismoreaffectedbycurrent.Withtheincreas