References: [1] Regulation, Structure of electrical systems and power lines, 2004. [2] Vasileva, M. (2007). High Voltage Technics, Varna: TU-Varna. [3] Goldstein., Korovin, Y., Prokudin. AV. (2010).Lightning overvoltages and switching surges in electrical systems. [4] Gerasimov, K., Kamenov, J. (2007). Modelling in power systems, Sofia. [5] Genov, L. G. (1974). Wave processes in the coils of the transformers, T.S. [6] Gindullin, F. (1989). Overvoltages in substation 6- 35 kV, M., Energoatom. |