The corona discharge from transmission lines in high-altitude areas is more severe than at lower altitudes. The radio interference caused thereby is a key factor to be considered when designing transmission lines. To ...The corona discharge from transmission lines in high-altitude areas is more severe than at lower altitudes. The radio interference caused thereby is a key factor to be considered when designing transmission lines. To study the influence of altitude on negative corona characteristics, an experimental platform comprising a movable small corona cage was established: experiments were conducted at four altitudes in the range of 1120-4320 m, and data on the corona current pulse and radio interference level of 0.8-mm diameter fine copper wire under different negative voltages were collected. The experimental results show that the average amplitude, repetition frequency and average current of the corona current pulse increase with increasing altitude. The dispersion of pulse amplitude increases with increase in altitude, while the randomness of the pulse interval decreases continuously. Taking the average current as an intermediate variable,the relationship between radio interference level and altitude is obtained. The result of this research has some significance for understanding the corona discharge characteristics of ultra-highvoltage lines.展开更多
Positive corona burst pulses are an unstable pulse mode.They appear in a small range of the onset stage,and their current pulses result from the collective movement of charged species.This paper focused on the connect...Positive corona burst pulses are an unstable pulse mode.They appear in a small range of the onset stage,and their current pulses result from the collective movement of charged species.This paper focused on the connections between these pulses and the collective movement of charged species.The movement of species is divided into four parts with respect to time:the(1)initial growth of species,(2)formation and development of the streamer region and negative ion sheath,(3)dead time(the time interval between the pulses),and(4)rapid re-growth of species.The movement of the species in the four parts and the correspondence with the current pulse were analyzed.The numerical results indicated the following:the rapid rising of the species matched the rising edge of the pulses,the streamer region,and negative ion sheath appeared in the falling edge of the primary pulse,and the rapid re-growth of species matched the re-ignition of the pulses.The results were in qualitative agreement with deductions and experimental observations in the literature.展开更多
The corona onset voltage gradient(COG)of conductors is a key parameter in the design of overhead transmission lines.The commonly used semi-empirical calculation formula proposed by Peek(1910s)at present can roughly es...The corona onset voltage gradient(COG)of conductors is a key parameter in the design of overhead transmission lines.The commonly used semi-empirical calculation formula proposed by Peek(1910s)at present can roughly estimate the COG of single conductors and is not applicable to large cross-section bundle conductors.In this paper,experiments are conducted to investigate the corona characteristics of a whole series of bundle conductors at different altitudes,and a prediction formula is proposed for the COG of large cross-section bundle conductors on AC transmission lines considering the altitude correction.The calculated values using the proposed prediction formula are compared with the experimental values of the COG in two cases:UHV eight-bundle conductors at an altitude of 19 m;500 kV UHV four-bundle conductors in Wuhan,Xining,Geermu,and Nachitai at four different altitudes.The results show that the use of the formula can predict the COG of bundle conductors with the radius of 1.34 cm to 1.995 cm and the number of subconductors of 4 to 12 at altitudes of 19 m to 4000 m above the mean sea level.The research findings can provide a reference for the design of EHV and UHV overhead transmission lines and even those in higher voltage levels.展开更多
Extra or ultra-high voltage transmission lines can exhibit strong corona discharge and generate severe audible noise(AN)at high altitudes,which has become a critical limiting factor for power lines construction.Howeve...Extra or ultra-high voltage transmission lines can exhibit strong corona discharge and generate severe audible noise(AN)at high altitudes,which has become a critical limiting factor for power lines construction.However,the AN data of bundle conductors at high altitudes are very rare,which cannot adequately support the power utilities to make reasonable conductor selections.In this paper,a sound pressure level(SPL)of 14 types of bundle conductors is investigated by using an ultra-high-voltage(UHV)corona cage(8 m×8 m×35 m)at an altitude of 2216 m,where the bundle numbers between 4 and 12 and the conductor types are used in 500 kV,750 kV or 1000 kV power transmission projects.Then a large number of valuable AN data are obtained;the influences of bundle numbers and sub-conductor diameters on an acoustic power density level(LPWL)are analyzed;and an A-weighted LPWL calculation method is proposed.In addition,by comparing the AN data obtained from the low-altitude area(altitude:23 m),the AN altitude correction factor is concluded,and the influences of conductor parameters and the surface electric field strength on correction factors are discussed.The results obtained in this paper can provide important data for the construction of high-altitude AC power lines.展开更多
基金supported by the Science and Technology Project of State Grid Corporation of China (No.5200202155587A-0-5-GC)。
文摘The corona discharge from transmission lines in high-altitude areas is more severe than at lower altitudes. The radio interference caused thereby is a key factor to be considered when designing transmission lines. To study the influence of altitude on negative corona characteristics, an experimental platform comprising a movable small corona cage was established: experiments were conducted at four altitudes in the range of 1120-4320 m, and data on the corona current pulse and radio interference level of 0.8-mm diameter fine copper wire under different negative voltages were collected. The experimental results show that the average amplitude, repetition frequency and average current of the corona current pulse increase with increasing altitude. The dispersion of pulse amplitude increases with increase in altitude, while the randomness of the pulse interval decreases continuously. Taking the average current as an intermediate variable,the relationship between radio interference level and altitude is obtained. The result of this research has some significance for understanding the corona discharge characteristics of ultra-highvoltage lines.
基金supported by National Natural Science Foundation of China(No.51907145)。
文摘Positive corona burst pulses are an unstable pulse mode.They appear in a small range of the onset stage,and their current pulses result from the collective movement of charged species.This paper focused on the connections between these pulses and the collective movement of charged species.The movement of species is divided into four parts with respect to time:the(1)initial growth of species,(2)formation and development of the streamer region and negative ion sheath,(3)dead time(the time interval between the pulses),and(4)rapid re-growth of species.The movement of the species in the four parts and the correspondence with the current pulse were analyzed.The numerical results indicated the following:the rapid rising of the species matched the rising edge of the pulses,the streamer region,and negative ion sheath appeared in the falling edge of the primary pulse,and the rapid re-growth of species matched the re-ignition of the pulses.The results were in qualitative agreement with deductions and experimental observations in the literature.
基金This work was supported by the National Natural Science Foundation of China(51577069,51277073)National Basic Research Programme of China(2011CB209401)+2 种基金the Science and Technology Project of State Grid Corporation of China(SGTYHT/15-JS-191)the Science and Technology Program of EPPEI(K201909-D)the Fundamental Research Funds for the Central Universities(2020MS092).
文摘The corona onset voltage gradient(COG)of conductors is a key parameter in the design of overhead transmission lines.The commonly used semi-empirical calculation formula proposed by Peek(1910s)at present can roughly estimate the COG of single conductors and is not applicable to large cross-section bundle conductors.In this paper,experiments are conducted to investigate the corona characteristics of a whole series of bundle conductors at different altitudes,and a prediction formula is proposed for the COG of large cross-section bundle conductors on AC transmission lines considering the altitude correction.The calculated values using the proposed prediction formula are compared with the experimental values of the COG in two cases:UHV eight-bundle conductors at an altitude of 19 m;500 kV UHV four-bundle conductors in Wuhan,Xining,Geermu,and Nachitai at four different altitudes.The results show that the use of the formula can predict the COG of bundle conductors with the radius of 1.34 cm to 1.995 cm and the number of subconductors of 4 to 12 at altitudes of 19 m to 4000 m above the mean sea level.The research findings can provide a reference for the design of EHV and UHV overhead transmission lines and even those in higher voltage levels.
基金National Natural Science Foundation of China(51907065)the Fundamental Research Funds for the Central Universities(2020MS097)。
文摘Extra or ultra-high voltage transmission lines can exhibit strong corona discharge and generate severe audible noise(AN)at high altitudes,which has become a critical limiting factor for power lines construction.However,the AN data of bundle conductors at high altitudes are very rare,which cannot adequately support the power utilities to make reasonable conductor selections.In this paper,a sound pressure level(SPL)of 14 types of bundle conductors is investigated by using an ultra-high-voltage(UHV)corona cage(8 m×8 m×35 m)at an altitude of 2216 m,where the bundle numbers between 4 and 12 and the conductor types are used in 500 kV,750 kV or 1000 kV power transmission projects.Then a large number of valuable AN data are obtained;the influences of bundle numbers and sub-conductor diameters on an acoustic power density level(LPWL)are analyzed;and an A-weighted LPWL calculation method is proposed.In addition,by comparing the AN data obtained from the low-altitude area(altitude:23 m),the AN altitude correction factor is concluded,and the influences of conductor parameters and the surface electric field strength on correction factors are discussed.The results obtained in this paper can provide important data for the construction of high-altitude AC power lines.
