High-voltage direct current(HVDC)cables are growing rapidly all over the world due to the development of offshore wind power interconnections,cross-island power interconnections,etc.Extensive research has been conduct...High-voltage direct current(HVDC)cables are growing rapidly all over the world due to the development of offshore wind power interconnections,cross-island power interconnections,etc.Extensive research has been conducted and many achievements have been made in the study of theoretical issues of HVDC insulation,structural design and manufacture of HVDC cables with the corresponding accessories,as well as in condition monitoring technology.展开更多
This paper reviews the existing testing techniques for high voltage direct current(HVDC)cable systems,following as a backbone the structure of CIGRE Technical Brochure(TB)852:2021‘Recommendations for testing DC extru...This paper reviews the existing testing techniques for high voltage direct current(HVDC)cable systems,following as a backbone the structure of CIGRE Technical Brochure(TB)852:2021‘Recommendations for testing DC extruded cable systems for power transmission at a rated voltage up to 800 kV’because it has a fairly similar structure to CIGRE TB 853:2021 for lapped DC cables,and especially because of the impressive spread of HVDC extruded cables experienced worldwide in the last 25 years.The review considers development tests,pre-qualification tests,extension of qualification test,type tests(with hints at IEEE 1732-2017 for space charge measurements in the qualification of HVDC extruded cables),routine tests(with hints at IEEE 2862-2020 for routine tests of HVDC extruded cable system joints),sample tests and after installation tests.The review also analyses CIGRE TB 853 for lapped HVDC cable systems,as these cables remain unbeaten for submarine applications at the highest sea depths.The main novelties of CIGRE TB 852 and 853 with respect to previous standards for HVDC cable systems(mainly CIGRE TB 496 and IEC 62895 for extruded cables and CIGRE Electra 189:2000 for lapped cables)are put under the spotlight-with focus on the so-called temporary over-voltage tests-together with the limits and gaps of CIGRE TB 852.The main HVDC cable system testing equipment that is usually employed for electro-thermal tests is also treated.Emphasis is given to CIGRE TB 490 to treat the peculiarities of submarine cable systems,as well as to mechanical tests,having CIGRE TB 623 as a reference,with particular focus on the special sea trial tests.An example of an innovative sea trial testing procedure is shown,which is the outcome of a fruitful partnership between a cable manufacturer and the national Transmission System Operator in Italy.展开更多
Polypropylene(PP)-based recyclable materials have attracted tremendous interest for HVDC cable insulation applications due to their superior electrical properties,e.g.,high thermal stability and superior recyclability...Polypropylene(PP)-based recyclable materials have attracted tremendous interest for HVDC cable insulation applications due to their superior electrical properties,e.g.,high thermal stability and superior recyclability.Compared with crosslinked polyethylene(XLPE),PP-based materials exhibit the advantages of not only higher working temperatures but also facile and efficient cable manufacturing with reduced costs,which are highly desirable in HVDC cable manufacturing.Considering their promising advantages,PP-based materials have received significant attention from both academia and industry in the field of HVDC cable insulation.In order to adopt PP as a cable insulation material,the mechanical flexibility of PP should be improved.However,regulations of the mechanical properties inevitably influences the electrical properties of PP.So extensive research has been conducted on the regulation of the mechanical and electrical properties of PP.This review summarizes the research progress on recyclable PP-based materials for HVDC cable insulation applications.Particular attention is placed on the electrical property regulations and material structure-property relationships.The challenges that remain to be addressed and the opportunities for future studies on PP-based recyclable HVDC cable insulation materials are also presented.展开更多
With the development of deep-sea wind power and large-scale onshore clean energy,the global demand for higher voltage level DC cable power transmission technology has become increasingly urgent.This paper systematical...With the development of deep-sea wind power and large-scale onshore clean energy,the global demand for higher voltage level DC cable power transmission technology has become increasingly urgent.This paper systematically reviews the technical advancements in high voltage direct current(HVDC)cable accessories,addressing design challenges of terminations and joints,insulation material performance,manufacturing processes for large-scale components,standard frameworks and long-term reliability.The core challenges in HVDC accessories are identified as conductivity matching of insulating materials,interface electric field regulation and multi-field coupling reliability,requiring synergistic optimisation of electrical,thermal and mechanical behaviours through the modification of rubber materials,interfacial compatibility and multi-physics field modelling.Silicon rubber and ethylene propylene diene monomer made in China have achieved electrical properties comparable to international standards,yet breakthroughs in tear resistance,process consistency and environmental sustainability remain critical.The injection moulding defect control and uniform moulding process of large rubber and epoxy parts demand further improvement.The standard system in China needs to be strengthened in terms of systematic certification and long-term reliability evaluation.Future research should prioritise eco-friendly material development,intelligent monitoring technologies and multi-field coupling ageing life prediction to enhance the reliability of HVDC cable systems under extreme voltages and complex operational scenarios.展开更多
This study examines transient overvoltage phenomena in 525 kV high-voltage direct current(HVDC)onshore cable systems,with particular emphasis on the influence of grounding configurations in two joint types:straight-th...This study examines transient overvoltage phenomena in 525 kV high-voltage direct current(HVDC)onshore cable systems,with particular emphasis on the influence of grounding configurations in two joint types:straight-through and screen-separated.Transient overvoltages arising from wave propagation and reflections are analysed,highlighting the impact of joint types,bonding cable configurations(coaxial vs.noncoaxial)and bonding cable length on the resulting overvoltage magnitudes.The necessity of modelling screen-to-earth representations of sectionalised cables at grounded joint locations in the vicinity of faults is emphasised,whereas simplified representations of ungrounded and grounded straight-through joints are identified as sufficient for system-level simulations.To address the computational challenges of detailed electromagnetic transient simulations,a stand-alone simplified circuit is proposed to analyse grounded joint transients and to mitigate errors caused by insufficient time-step resolution.The results provide practical insights for insulation coordination,supporting the reliable integration of HVDC technology into long-distance cable-based transmission networks while enhancing system resilience.展开更多
This paper focuses on the space charge and breakdown characteristics of polypropylene(PP)-based insulation interface in extrusion moulded joint(EMJ)for high-voltage direct current(HVDC)submarine cables.The double-laye...This paper focuses on the space charge and breakdown characteristics of polypropylene(PP)-based insulation interface in extrusion moulded joint(EMJ)for high-voltage direct current(HVDC)submarine cables.The double-layered flat samples and cylindrical samples are prepared to imitate the interface in the PP-insulated EMJ.The DC conductivity,space charge,and breakdown strength are tested.The results demonstrate that in the EMJ manufacturing process,the lower wielding temperature leads to microdefects at the insulation interface.As shallow traps,the microdefects exacerbate hetero charge accumulation,thereby intensifying the electric field distortion and increasing the conductivity.Meanwhile,the interfacial microdefects lead to a reduction in the insulation breakdown strength.At 90°C,the normal and tangential breakdown strengths decrease by a maximum of 20.6%and 54.5%,respectively.Notably,the space charges and microdefects lead to a rapid decline in the breakdown strength after hetero polarity pre-stressing.Especially for the tangential breakdown strength,the maximum decrease rate reaches 22.9%.Therefore,the interfacial microdefects caused by the drop in the welding temperature are the primary factors leading to a serious decrease in the electrical properties of EMJ insulation,making the EMJ insulation weaker than PP cable insulation.展开更多
文摘High-voltage direct current(HVDC)cables are growing rapidly all over the world due to the development of offshore wind power interconnections,cross-island power interconnections,etc.Extensive research has been conducted and many achievements have been made in the study of theoretical issues of HVDC insulation,structural design and manufacture of HVDC cables with the corresponding accessories,as well as in condition monitoring technology.
文摘This paper reviews the existing testing techniques for high voltage direct current(HVDC)cable systems,following as a backbone the structure of CIGRE Technical Brochure(TB)852:2021‘Recommendations for testing DC extruded cable systems for power transmission at a rated voltage up to 800 kV’because it has a fairly similar structure to CIGRE TB 853:2021 for lapped DC cables,and especially because of the impressive spread of HVDC extruded cables experienced worldwide in the last 25 years.The review considers development tests,pre-qualification tests,extension of qualification test,type tests(with hints at IEEE 1732-2017 for space charge measurements in the qualification of HVDC extruded cables),routine tests(with hints at IEEE 2862-2020 for routine tests of HVDC extruded cable system joints),sample tests and after installation tests.The review also analyses CIGRE TB 853 for lapped HVDC cable systems,as these cables remain unbeaten for submarine applications at the highest sea depths.The main novelties of CIGRE TB 852 and 853 with respect to previous standards for HVDC cable systems(mainly CIGRE TB 496 and IEC 62895 for extruded cables and CIGRE Electra 189:2000 for lapped cables)are put under the spotlight-with focus on the so-called temporary over-voltage tests-together with the limits and gaps of CIGRE TB 852.The main HVDC cable system testing equipment that is usually employed for electro-thermal tests is also treated.Emphasis is given to CIGRE TB 490 to treat the peculiarities of submarine cable systems,as well as to mechanical tests,having CIGRE TB 623 as a reference,with particular focus on the special sea trial tests.An example of an innovative sea trial testing procedure is shown,which is the outcome of a fruitful partnership between a cable manufacturer and the national Transmission System Operator in Italy.
基金supported by the National Natural Science Foundation of China(No.51921005).
文摘Polypropylene(PP)-based recyclable materials have attracted tremendous interest for HVDC cable insulation applications due to their superior electrical properties,e.g.,high thermal stability and superior recyclability.Compared with crosslinked polyethylene(XLPE),PP-based materials exhibit the advantages of not only higher working temperatures but also facile and efficient cable manufacturing with reduced costs,which are highly desirable in HVDC cable manufacturing.Considering their promising advantages,PP-based materials have received significant attention from both academia and industry in the field of HVDC cable insulation.In order to adopt PP as a cable insulation material,the mechanical flexibility of PP should be improved.However,regulations of the mechanical properties inevitably influences the electrical properties of PP.So extensive research has been conducted on the regulation of the mechanical and electrical properties of PP.This review summarizes the research progress on recyclable PP-based materials for HVDC cable insulation applications.Particular attention is placed on the electrical property regulations and material structure-property relationships.The challenges that remain to be addressed and the opportunities for future studies on PP-based recyclable HVDC cable insulation materials are also presented.
基金supported by the Science and Technology Project of SGCC(521001250033-246-YYGG).
文摘With the development of deep-sea wind power and large-scale onshore clean energy,the global demand for higher voltage level DC cable power transmission technology has become increasingly urgent.This paper systematically reviews the technical advancements in high voltage direct current(HVDC)cable accessories,addressing design challenges of terminations and joints,insulation material performance,manufacturing processes for large-scale components,standard frameworks and long-term reliability.The core challenges in HVDC accessories are identified as conductivity matching of insulating materials,interface electric field regulation and multi-field coupling reliability,requiring synergistic optimisation of electrical,thermal and mechanical behaviours through the modification of rubber materials,interfacial compatibility and multi-physics field modelling.Silicon rubber and ethylene propylene diene monomer made in China have achieved electrical properties comparable to international standards,yet breakthroughs in tear resistance,process consistency and environmental sustainability remain critical.The injection moulding defect control and uniform moulding process of large rubber and epoxy parts demand further improvement.The standard system in China needs to be strengthened in terms of systematic certification and long-term reliability evaluation.Future research should prioritise eco-friendly material development,intelligent monitoring technologies and multi-field coupling ageing life prediction to enhance the reliability of HVDC cable systems under extreme voltages and complex operational scenarios.
文摘This study examines transient overvoltage phenomena in 525 kV high-voltage direct current(HVDC)onshore cable systems,with particular emphasis on the influence of grounding configurations in two joint types:straight-through and screen-separated.Transient overvoltages arising from wave propagation and reflections are analysed,highlighting the impact of joint types,bonding cable configurations(coaxial vs.noncoaxial)and bonding cable length on the resulting overvoltage magnitudes.The necessity of modelling screen-to-earth representations of sectionalised cables at grounded joint locations in the vicinity of faults is emphasised,whereas simplified representations of ungrounded and grounded straight-through joints are identified as sufficient for system-level simulations.To address the computational challenges of detailed electromagnetic transient simulations,a stand-alone simplified circuit is proposed to analyse grounded joint transients and to mitigate errors caused by insufficient time-step resolution.The results provide practical insights for insulation coordination,supporting the reliable integration of HVDC technology into long-distance cable-based transmission networks while enhancing system resilience.
基金National Natural Science Foundation of China under the Grant 52477151 and 52077148Key Science and Technology Programme of Yunnan Province,China under Grant 202202AC080002.
文摘This paper focuses on the space charge and breakdown characteristics of polypropylene(PP)-based insulation interface in extrusion moulded joint(EMJ)for high-voltage direct current(HVDC)submarine cables.The double-layered flat samples and cylindrical samples are prepared to imitate the interface in the PP-insulated EMJ.The DC conductivity,space charge,and breakdown strength are tested.The results demonstrate that in the EMJ manufacturing process,the lower wielding temperature leads to microdefects at the insulation interface.As shallow traps,the microdefects exacerbate hetero charge accumulation,thereby intensifying the electric field distortion and increasing the conductivity.Meanwhile,the interfacial microdefects lead to a reduction in the insulation breakdown strength.At 90°C,the normal and tangential breakdown strengths decrease by a maximum of 20.6%and 54.5%,respectively.Notably,the space charges and microdefects lead to a rapid decline in the breakdown strength after hetero polarity pre-stressing.Especially for the tangential breakdown strength,the maximum decrease rate reaches 22.9%.Therefore,the interfacial microdefects caused by the drop in the welding temperature are the primary factors leading to a serious decrease in the electrical properties of EMJ insulation,making the EMJ insulation weaker than PP cable insulation.
