Impact of Weather(Fog) on Corona Loss and Its Geographical Variation within Eastern Region

India experiences diverse climatic conditions ranging from tropical in the south to temperate and alpine in the Himalayan north. As the EHV transmission network of India is spread across the length and breadth of the country, it is quite natural that the national grid too is subjected to different climatic conditions. Even different parts of the same overhead 765 kV or 400 kV long line experience different weather conditions at the same time, as the line passes through different weather zones. Depending upon the season, the transmission network is exposed to different extreme weather conditions. Though the overhead lines are well designed to endure these diverse weather conditions while maintaining reliability margin, but their performance is to some extent influenced by the climatic condition. One of the performance indices is its loss. The ohmic loss is dependent on the power flow and not much affected by weather. But corona loss which takes place in EHV transmission network is greatly influenced by the weather condition and seasonal change in the country. This paper aims at identifying the area in the eastern grid of the country where corona loss variation is more in different season. Some measures to minimize such loss are also suggested.