Surge protection of generators directly connected to a medium voltage network

The paper presents the results of the surge protection study of a generator in a small hydro power plant that is directly connected to the overhead network. Overhead lines pass through to the area of high isoceraunic activity with high specific resistance of soil. Lightning striking overhead lines produce voltage transients that can harm insulation of a generator winding. The parameters for the generator model were obtained by calculation and measurement. The simulation model is presented, and results of the simulations are given. The improvement of surge protection is achieved by installation of additional surge arresters connected to generator terminals and at neutral point. It is recommended to conduct surge protection analysis for each generator which is designed to be directly connected to the overhead line.