Galloping of conductor is a major hazard to safe operation of transmission lines. This paper introduces the basic galloping stability mechanism of conductor, design method of anti-galloping and the application of anti...Galloping of conductor is a major hazard to safe operation of transmission lines. This paper introduces the basic galloping stability mechanism of conductor, design method of anti-galloping and the application of anti-galloping double pendulum and integral eccentric pendulum in China. Galloping stability mechanism of conductor was established based on vertical galloping mechanism developed by Den Hartog and torsional galloping mechanism developed by O. Nigel. A design method of anti-galloping was derived and anti-galloping double pendulum and integral eccentric pendulum were developed. Applications to several transmission lines including a 500 kV transmission line of large span indicated that they have played important roles in anti-galloping.展开更多
Corona discharge suppression for high-voltage direct-current(HVDC)transmission lines at line terminals such as converter stations is a subject that requires attention.In this paper,a method based on a conductor covere...Corona discharge suppression for high-voltage direct-current(HVDC)transmission lines at line terminals such as converter stations is a subject that requires attention.In this paper,a method based on a conductor covered with dielectric film is proposed and implemented through a bench-scale setup.Compared with the bare conductor,the corona discharge suppression effect of the dielectric-film-covered conductor under positive polarity is studied from the composite field strength and ion current density using a line-plate experimental device.The influences of film thickness and film material on the corona discharge suppression effect are investigated.The charge accumulation and dissipation characteristics of different film materials are also studied.The results show that the conductor covered with dielectric film has excellent ability to inhibit corona discharge.The ground-level composite field strength of the conductor covered with dielectric film is lower than its nominal field strength,and its ion current density is at the nA m^(−2) level.The corona threshold voltage can be promoted by increasing the film thickness,but the ability to inhibit corona discharge becomes weak.The larger the surface electric field strength,the more charge accumulated,but the faster the charge dissipation rate.Compared with polyvinyl chloride film,cross-linked polyethylene film has stronger charge accumulation ability and slower charge dissipation rate,which can better restrain the corona discharge of HVDC transmission lines.展开更多
This paper introduces the current application status and technical level development of large section conductor and heat-resistant conductor transmission technology in China, analyzes the role of the two design scheme...This paper introduces the current application status and technical level development of large section conductor and heat-resistant conductor transmission technology in China, analyzes the role of the two design schemes of large section conductor and heat-resistant conductor in promoting the establishment of power system stability, and analyzes the characteristics of the two transmission technologies combined with the application of the two transmission modes in China's power system advantages and future development space. Due to the shortage of line corridors in some areas of China, in order to meet people's power demand, it is necessary to transform the transmission line, compare the application value, parameter calculation and economic benefits of heat-resistant conductor and large section conductor, so as to contribute to the engineering development of overhead transmission line projects in China.展开更多
As the main part of the transmission line, the conductor is responsible for the long-distance transmission of electric energy. It should not only ensure the safe operation, but also minimize the loss. The proper selec...As the main part of the transmission line, the conductor is responsible for the long-distance transmission of electric energy. It should not only ensure the safe operation, but also minimize the loss. The proper selection of conductors is of great significance to the construction, safe operation, environmental and economic benefits of the power grid. Entering the "14th Five-Year Plan" period, peak carbon dioxide emissions, Carbon Neutralization have been listed as one of the key tasks of the next central economic work conference. It is increasingly urgent to reasonably control carbon emissions and build a low-carbon economy and ecological harmonious development. As the lifeline of the country, power transmission lines account for a large proportion of the construction scale and energy consumption. Therefore, energy conservation and emission reduction are crucial. This study considers the carbon emission index method in the annual fee usage concept, and reasonably quantifies the carbon emission into the whole operation of the project as an analysis factor. In the study, carbon emissions are integrated into the cost management of annual fee, and the optimal scheme is selected from the overall consideration of comprehensive benefits such as technology, ecological environment and economy.展开更多
Increasing the charging cut-off voltage can significantly enhance the energy density of LiCoO_(2).However,the continuous deterioration of interface structure and transport kinetics under high voltage poses challenges ...Increasing the charging cut-off voltage can significantly enhance the energy density of LiCoO_(2).However,the continuous deterioration of interface structure and transport kinetics under high voltage poses challenges to electrochemical stability.This work proposes to in-situ construct a uniform element gradient modification structure on the surface and subsurface of LiCoO_(2).The modification structure contains an Sb_(2)O_(3)&SbF_(x)composite coating layer and an Sb-F doped spinel-like transition layer,simultaneously.The modified sample maintains an initial discharge specific capacity of 221.2 mA h g^(-1)and a capacity retention of 86%after 200 cycles at 3–4.6 V and 0.5 C.Moreover,it has a discharge specific capacity of163.3 mA h g^(-1)at a high rate of 5 C.Meanwhile,combining highly electronegative Sb^(3+)&F^(-)that widen the Li^(+)transport channel with the amorphous coating of F^(-)doped Sb_(2)O_(3)with higher conductivity improves the interface transport kinetics.This breaks the stereotypical view in traditional concepts that fluorinated coatings or inert metal oxide coatings inhibit Li^(+)transport.Moreover,the inert composite coating combined with Sb–O–F with high bond energy stabilizes the surface structure.A series of characterizations confirm that the joint improvement of interface structure stability and transport kinetics significantly enhances the electrochemical performance of LiCoO_(2).展开更多
In the harsh environment,the structural health of the anti-vibration hammer,which suffers from the coupled effects of corrosion and fatigue damage,is significantly reduced.As part of the conductor structure,the anti-v...In the harsh environment,the structural health of the anti-vibration hammer,which suffers from the coupled effects of corrosion and fatigue damage,is significantly reduced.As part of the conductor structure,the anti-vibration hammer is rigidly attached to the conductor,effectively suppressing conductor vibration.The conductor’s breeze vibration law and natural modal frequency are altered damage to the anti-vibration hammer structure.Through built a vibration experiment platform to simulate multiple faults such as anti-vibration hammer head drop off and position slippage,which to obtained the vibration acceleration signal of the conductor.The acceleration vibration signal is processed and analyzed in the time and frequency domains.The results are used to derive the breeze vibration law of the conductor under multiple faults and propose an anti-vibration hammer damage online monitoring technology.The results show that the vibration acceleration value and vibration intensity of the conductor are significantly increased after the anti-vibration hammer damage.The natural frequency increases for each order,with an absolute change ranging from 0.15 to 6.49 Hz.The anti-vibration hammer slipped due to a loose connection,the 1st natural frequency increases from 8.18 to 16.62 Hz.Therefore,in engineering applications,there can be no contact to determine the anti-vibration hammer damage situation by monitoring the modal natural frequency of the conductor.This is even a tiny damage that cannot be seen.This method will prevent the further expansion of the damage that can cause accidents.展开更多
The authors aim to explore the effectiveness of two-component polyurea materials applied to transmission line towers(on the ground potential side)in improving the insulation performance of the conductor-tower gap.The ...The authors aim to explore the effectiveness of two-component polyurea materials applied to transmission line towers(on the ground potential side)in improving the insulation performance of the conductor-tower gap.The physicochemical and electrical properties of the polyurea materials were first analysed and a conductor-tower gap testing platform was constructed to investigate the effects of the length and thickness of the polyurea layer on the ground potential side under a 50-Hz AC voltage on the breakdown characteristics.Experimental studies revealed that the characteristic breakdown voltages of polyurea layers of different lengths(40,100,200,and 400 cm)are approximate.Compared with the air-insulated gap before the application of polyurea,thinner polyurea layers(1 and 2 mm)showed no significant improvement in the breakdown voltage,whereas thicker layers(3,4,and 5 mm)significantly improved it.In particular,with a polyurea layer thickness of 4 mm and gap distance of 20 cm,the characteristic breakdown voltage increased from 138.43 to 155.71 kV.In addition,the withstand voltage distance decreased from 4 to 3 cm without any breakdown,even when the high-voltage conductor directly contacted the polyurea layer and the layer was not penetrated.The authors provide theoretical support and experimental data for improving the conductor-tower gap insulation performance by applying a polyurea layer on the ground potential side.展开更多
文摘Galloping of conductor is a major hazard to safe operation of transmission lines. This paper introduces the basic galloping stability mechanism of conductor, design method of anti-galloping and the application of anti-galloping double pendulum and integral eccentric pendulum in China. Galloping stability mechanism of conductor was established based on vertical galloping mechanism developed by Den Hartog and torsional galloping mechanism developed by O. Nigel. A design method of anti-galloping was derived and anti-galloping double pendulum and integral eccentric pendulum were developed. Applications to several transmission lines including a 500 kV transmission line of large span indicated that they have played important roles in anti-galloping.
基金by State Grid Shandong Electric Power Company(52062618001M)。
文摘Corona discharge suppression for high-voltage direct-current(HVDC)transmission lines at line terminals such as converter stations is a subject that requires attention.In this paper,a method based on a conductor covered with dielectric film is proposed and implemented through a bench-scale setup.Compared with the bare conductor,the corona discharge suppression effect of the dielectric-film-covered conductor under positive polarity is studied from the composite field strength and ion current density using a line-plate experimental device.The influences of film thickness and film material on the corona discharge suppression effect are investigated.The charge accumulation and dissipation characteristics of different film materials are also studied.The results show that the conductor covered with dielectric film has excellent ability to inhibit corona discharge.The ground-level composite field strength of the conductor covered with dielectric film is lower than its nominal field strength,and its ion current density is at the nA m^(−2) level.The corona threshold voltage can be promoted by increasing the film thickness,but the ability to inhibit corona discharge becomes weak.The larger the surface electric field strength,the more charge accumulated,but the faster the charge dissipation rate.Compared with polyvinyl chloride film,cross-linked polyethylene film has stronger charge accumulation ability and slower charge dissipation rate,which can better restrain the corona discharge of HVDC transmission lines.
文摘This paper introduces the current application status and technical level development of large section conductor and heat-resistant conductor transmission technology in China, analyzes the role of the two design schemes of large section conductor and heat-resistant conductor in promoting the establishment of power system stability, and analyzes the characteristics of the two transmission technologies combined with the application of the two transmission modes in China's power system advantages and future development space. Due to the shortage of line corridors in some areas of China, in order to meet people's power demand, it is necessary to transform the transmission line, compare the application value, parameter calculation and economic benefits of heat-resistant conductor and large section conductor, so as to contribute to the engineering development of overhead transmission line projects in China.
文摘As the main part of the transmission line, the conductor is responsible for the long-distance transmission of electric energy. It should not only ensure the safe operation, but also minimize the loss. The proper selection of conductors is of great significance to the construction, safe operation, environmental and economic benefits of the power grid. Entering the "14th Five-Year Plan" period, peak carbon dioxide emissions, Carbon Neutralization have been listed as one of the key tasks of the next central economic work conference. It is increasingly urgent to reasonably control carbon emissions and build a low-carbon economy and ecological harmonious development. As the lifeline of the country, power transmission lines account for a large proportion of the construction scale and energy consumption. Therefore, energy conservation and emission reduction are crucial. This study considers the carbon emission index method in the annual fee usage concept, and reasonably quantifies the carbon emission into the whole operation of the project as an analysis factor. In the study, carbon emissions are integrated into the cost management of annual fee, and the optimal scheme is selected from the overall consideration of comprehensive benefits such as technology, ecological environment and economy.
基金supported by the National Natural Science Foundation of China(22075170)employed resources from the BL11B station of the Shanghai Synchrotron Radiation Facility(SSRF,under contract number:2023-SSRF-PT-502681)。
文摘Increasing the charging cut-off voltage can significantly enhance the energy density of LiCoO_(2).However,the continuous deterioration of interface structure and transport kinetics under high voltage poses challenges to electrochemical stability.This work proposes to in-situ construct a uniform element gradient modification structure on the surface and subsurface of LiCoO_(2).The modification structure contains an Sb_(2)O_(3)&SbF_(x)composite coating layer and an Sb-F doped spinel-like transition layer,simultaneously.The modified sample maintains an initial discharge specific capacity of 221.2 mA h g^(-1)and a capacity retention of 86%after 200 cycles at 3–4.6 V and 0.5 C.Moreover,it has a discharge specific capacity of163.3 mA h g^(-1)at a high rate of 5 C.Meanwhile,combining highly electronegative Sb^(3+)&F^(-)that widen the Li^(+)transport channel with the amorphous coating of F^(-)doped Sb_(2)O_(3)with higher conductivity improves the interface transport kinetics.This breaks the stereotypical view in traditional concepts that fluorinated coatings or inert metal oxide coatings inhibit Li^(+)transport.Moreover,the inert composite coating combined with Sb–O–F with high bond energy stabilizes the surface structure.A series of characterizations confirm that the joint improvement of interface structure stability and transport kinetics significantly enhances the electrochemical performance of LiCoO_(2).
基金supported by the National Natural Science Foundation of China(No.52007138)the Natural Science Basis Research Plan in Shaanxi Province of China(No.2022JQ-568)the Key Research and Development Program of Shaanxi Province(No.2023-YBGY-069).
文摘In the harsh environment,the structural health of the anti-vibration hammer,which suffers from the coupled effects of corrosion and fatigue damage,is significantly reduced.As part of the conductor structure,the anti-vibration hammer is rigidly attached to the conductor,effectively suppressing conductor vibration.The conductor’s breeze vibration law and natural modal frequency are altered damage to the anti-vibration hammer structure.Through built a vibration experiment platform to simulate multiple faults such as anti-vibration hammer head drop off and position slippage,which to obtained the vibration acceleration signal of the conductor.The acceleration vibration signal is processed and analyzed in the time and frequency domains.The results are used to derive the breeze vibration law of the conductor under multiple faults and propose an anti-vibration hammer damage online monitoring technology.The results show that the vibration acceleration value and vibration intensity of the conductor are significantly increased after the anti-vibration hammer damage.The natural frequency increases for each order,with an absolute change ranging from 0.15 to 6.49 Hz.The anti-vibration hammer slipped due to a loose connection,the 1st natural frequency increases from 8.18 to 16.62 Hz.Therefore,in engineering applications,there can be no contact to determine the anti-vibration hammer damage situation by monitoring the modal natural frequency of the conductor.This is even a tiny damage that cannot be seen.This method will prevent the further expansion of the damage that can cause accidents.
基金National Natural Science Foundation of China,Grant/Award Number:52207023。
文摘The authors aim to explore the effectiveness of two-component polyurea materials applied to transmission line towers(on the ground potential side)in improving the insulation performance of the conductor-tower gap.The physicochemical and electrical properties of the polyurea materials were first analysed and a conductor-tower gap testing platform was constructed to investigate the effects of the length and thickness of the polyurea layer on the ground potential side under a 50-Hz AC voltage on the breakdown characteristics.Experimental studies revealed that the characteristic breakdown voltages of polyurea layers of different lengths(40,100,200,and 400 cm)are approximate.Compared with the air-insulated gap before the application of polyurea,thinner polyurea layers(1 and 2 mm)showed no significant improvement in the breakdown voltage,whereas thicker layers(3,4,and 5 mm)significantly improved it.In particular,with a polyurea layer thickness of 4 mm and gap distance of 20 cm,the characteristic breakdown voltage increased from 138.43 to 155.71 kV.In addition,the withstand voltage distance decreased from 4 to 3 cm without any breakdown,even when the high-voltage conductor directly contacted the polyurea layer and the layer was not penetrated.The authors provide theoretical support and experimental data for improving the conductor-tower gap insulation performance by applying a polyurea layer on the ground potential side.
