Lightning-Induced Overvoltages Transmitted Over Distribution Transformer With MV Spark-Gap Operation—Part II: Mitigation Using LV Surge Arrester

When the distribution transformers are exposed to lightning overvoltages, it is worthy to study the low-voltage (LV) network response at the customer terminals using an accurate and simplified high-frequency transformer model. The impact of LV network feeder numbers, lengths, types, and loads on the lightning-induced overvoltage reached at the service entrance point is investigated. The high-frequency model representation of distribution transformer and the LV network are combined in a single arrangement in the environment of the Alternative Transients Programs/Electromagnetic Transients Program. Finally, a study is carried out to mitigate the overvoltages by allocating the surge arrester at the secondary side of the distribution transformer concerning the medium-voltage spark-gap operation. A simplified surge arrester model is represented and verified. This study can enhance the overvoltage protection of Finnish LV networks.