Direct Lightning Impact Assessment on a Rural Mini-Grid of Nepal

Lightning-related damage to overhead medium-voltage distribution networks is one of the prime concerns in power systems. This paper discusses distribution network modeling techniques required for lightning studies. The presented models of lightning current, line conductors, line insulators, distribution poles, grounding, distribution transformers, and surge arresters have been used for a direct lightning simulation case study. The case study is done in an eight kilometers long rural mini-grid of Nepal, where seven synchronous generators and seven distribution transformers are closely located. From this study, the dead-end low-voltage side and the midway medium-voltage side were found to be most stressed. So, it is recommended to use appropriate arresters at the low-voltage side of dead-end distribution transformers specifically to protect generators and low-voltage consumer appliances. Similarly, higher energy duty arresters can be installed at the medium-voltage bushing of midway transformers for better performance and reliability.