Test Study on Corona Onset Voltage of UHV Transmission Lines Based on UV Detection

Corona discharge is being detected by UV imaging detection technology at home and abroad in recent years. This technology is used in the corona tests of bundled conductors in this paper. In order to further research the corona characteristic, optimize geometry parameters and diameter of sub-conductor, and increase corona onset voltage of transmission lines, corona tests of three mode conductors which are placed inside the outdoor corona cage are conducted. Corona cage could be used to simulate the corona activities on transmission lines under a low voltage and different conditions in an effective and economical way. Photon which was created by UV light as a result of corona discharge on conductors is detected by the UV detection apparatus. The photon number within unit interval, namely photon counting rate is adopted as the parameter of quantifying the intensity of corona discharge. According to the apparent change of photon number, corona onset voltage can be judged. All tests are conducted under almost same atmosphere condition. Using the method, corona onset voltage is acquired. The results indicate that the tests have a good repeatability, in other words, repeat same test twice can acquires same result. The corona onset voltage can be acquired exactly from the curve of applied voltage vs. photon counting rate. Therefore UV detection apparatus can not only used to find discharge point exactly, but also applied on corona discharge research and live detection for power equipments. The method using in this paper is proved that is a new available method.