Due to its excellent insulation and mechanical properties,cross-linked polyethylene(XLPE)is widely used as the insulation candidate of power cables in power transmission and distribution systems.However,its performanc...Due to its excellent insulation and mechanical properties,cross-linked polyethylene(XLPE)is widely used as the insulation candidate of power cables in power transmission and distribution systems.However,its performance can be affected due to various stresses,which endangers safe operation of the power system in service.In this paper,dielectric and insulation properties of XLPE materials of 110 kV cables with the service lives of 0,15,and 30 years were tested and evaluated.Results show that with increase of service life,dielectric loss caused by the polarization process increases significantly,and dielectric strength decreases as well.Power frequency breakdown field strength and crystallinity decrease significantly,and carbonyl index increases.The degradation process of XLPE can be divided into two stages:the structure of the crystalline region of the original sample is relatively complete,and loss can be almost ignored.After long-term service,the crystallization region is destroyed,and thermal oxygen reaction occurs.Intermolecular force is weakened,which makes breakdown easier to occur.However,there is no direct relation between the carbonyl index and macroscopic characteristics.This paper reveals the deterioration law of the XLPE cable insulation,which provides a theoretical basis for evaluating cable aging condition and is of great significance to improve cable operation safety and maintenance quality.展开更多
High-voltage DC(HVDC)cables show more efficiency than high-voltage AC cables over the long distance power transmission and have attracted significant attention recently due to rapid developments in off-shore wind farm...High-voltage DC(HVDC)cables show more efficiency than high-voltage AC cables over the long distance power transmission and have attracted significant attention recently due to rapid developments in off-shore wind farm.Polypropylene laminated paper(PPLP)insulation based HVDC cables have provided a reliable operation for many years and are the highest voltage level in operation at the moment.In this study,the authors intend to understand the electrical performance of PPLP insulation system by examining space charge in detail,especially at the interfaces.It has been found that the interface between polypropylene and Kraft paper acts as trap for charge carriers,resulting in an optimal electric field distribution in PPLP insulation system.The optimal electric field distribution enhances overall electrical performance of PPLP insulation,including higher dc breakdown strength and lower electrical conductivity.展开更多
基金supported by the National Natural Science Foundation of China under Grant No.11975052,51507135,52107029supported by China Postdoctoral Science Foundation(No.2021M692599).
文摘Due to its excellent insulation and mechanical properties,cross-linked polyethylene(XLPE)is widely used as the insulation candidate of power cables in power transmission and distribution systems.However,its performance can be affected due to various stresses,which endangers safe operation of the power system in service.In this paper,dielectric and insulation properties of XLPE materials of 110 kV cables with the service lives of 0,15,and 30 years were tested and evaluated.Results show that with increase of service life,dielectric loss caused by the polarization process increases significantly,and dielectric strength decreases as well.Power frequency breakdown field strength and crystallinity decrease significantly,and carbonyl index increases.The degradation process of XLPE can be divided into two stages:the structure of the crystalline region of the original sample is relatively complete,and loss can be almost ignored.After long-term service,the crystallization region is destroyed,and thermal oxygen reaction occurs.Intermolecular force is weakened,which makes breakdown easier to occur.However,there is no direct relation between the carbonyl index and macroscopic characteristics.This paper reveals the deterioration law of the XLPE cable insulation,which provides a theoretical basis for evaluating cable aging condition and is of great significance to improve cable operation safety and maintenance quality.
基金the financial support received from UK Engineering and Physical Sciences Research Council(EP/L021560/1-Towards Enhanced HVDC Cable Systems)The further financial support from Shaanxi Electric Power Research Institute,China(SGTYHT/16-JS-200)is also essential.
文摘High-voltage DC(HVDC)cables show more efficiency than high-voltage AC cables over the long distance power transmission and have attracted significant attention recently due to rapid developments in off-shore wind farm.Polypropylene laminated paper(PPLP)insulation based HVDC cables have provided a reliable operation for many years and are the highest voltage level in operation at the moment.In this study,the authors intend to understand the electrical performance of PPLP insulation system by examining space charge in detail,especially at the interfaces.It has been found that the interface between polypropylene and Kraft paper acts as trap for charge carriers,resulting in an optimal electric field distribution in PPLP insulation system.The optimal electric field distribution enhances overall electrical performance of PPLP insulation,including higher dc breakdown strength and lower electrical conductivity.
