With the development of energy resources in the central and western regions of China,extra-high-voltage(EHV)and ultra-high-voltage(UHV)transmission project has become the main way of electric energy transmission in high altitude areas.There are a lot of sphere-plane gaps in the valve hall of the converter station in EHV/UHV DC trans-mission projects,and the insulation strength of the air gap decreases with the increase of altitude.In order to ensure the insulation safety of transmission lines in high altitude areas,the positive switching impulse tests of spherical electrodes with diameter of 0.3～1.1 m at gap distance of 1～3 m were carried out in Wuhan(altitude of 20 m)and Kunming(altitude of 2100 m),respectively.The effects of air pressure,spherical electrode size and gap distance on sphere-plane discharge characteristics were analyzed.Moreover,the applicability of the existing discharge voltage correction method for sphere-plate gap at high altitude was discussed.The results show that the existing method based on g parameter has a large error in correcting the discharge voltage of sphere-plane gap at reduced air pressure.Finally,based on the discharge physical process and test data,an improved discharge voltage correction method is proposed,which can provide a basis for reasonably determining the value of sphere-plane air gap under low pressure and ensuring the safe and stable operation of transmission lines in high altitude areas.
关键词
球-板间隙/高海拔/操作冲击/放电特性/电压校正
Key words
sphere-plane air gap/high altitude/positive switching impulse/discharge characteristics/voltage correction
维普
万方数据