People's Democratic Republic of Algeria Ministry of Higher Education and Scientific Research Larbi Ben M’Hidi University, Oum El Bouaghi (Algeria) Faculty of Sciences and Applied Sciences Department of Electrical Engineering A graduation thesis Submitted in partial fulfillment of the requirements for the degree of MASTER Option: ELECTRICAL POWER SYSTEM Theme Overvoltages Evaluation in Transformation Substations under Lightning effect ———– AUTHORS ———– BENDRISS Badreddine ———– SUPERVISOR ———– Dr. BEDOUI Samir -July 2019-