Performance evaluation of distribution and low-voltage networks under direct lightning flashes with paralleled triac-surge arrester

The service continuity of the distribution electrical network faces challenges. Among these challenges is the provision of protection against surge arrester failure, in which it is recommended to be installed instead of the existing spark-gap. The medium-voltage surge arrester (MVSA) is recently recommended to be protected using a power electronic device (triac) to bypass the exceeding dissipated energy. Therefore, the impact of the protected MVSA operation on its dissipated energy as well as the network performance is investigated under direct lightning flashes on the MV network. On the same concept of the study, the effect of the stroked low-voltage network by direct flashes to the customers and the medium-voltage network is evaluated without and with the protection of the MVSA. Thus, the importance of installing a low-voltage surge arrester (LVSA) is investigated. Accordingly, the protected LVSA using a power electronic device is introduced, and its operation impact on the network performance is evaluated. Occurrence of insulator flashover is investigated using a well-known flashover criterion, disruptive effect. This study is conducted under direct strokes based on the IEC standard. These direct flashes are considered as 200 kA and 10/350 mu s for positive first stroke and 50 kA and 0.25/100 mu s for negative subsequent strokes. Additionally, the impact of the low magnitude of the direct lightning stroke of 10 kA and 1.8/50 mu s on the network performance is studied. The Alternative Transient/Electromagnetic transient program (ATP/EMTP) and MATLAB software are used to perform simulations and analyze the results. The results confirm that the operation of the triac at the medium-voltage side produces reliable protection for MVSA. However, dangerous overvoltages are transmitted through the distribution transformer to the customers. Therefore, protection against LVSA failure is also recommended. This study introduces a guarantee of service continuity by replacing the existing spark-gap with a protected surge arrester.