The basic task of this diploma thesis is the description of the basic settings of the protection of power plants against direct lightning strikes, with the focus of the work on the description of methods for modeling the arrester system, using an electrogeometric model. In the first part of the thesis, the features of the lightning current are described. From the point of view of protection, the lightning current is the most important quantity, which is why the peak value of the lightning current, the steepness of the lightning current, the charge of the lightning current, the square impulse of the lightning current and the density of the lightning current are described. It also describes the basic protection of power lines and plants using grippers, protective ropes, protective spark arrestors and surge arresters. The second part describes the technical features of the lightning protection system, which serves to reduce physical damage due to a direct lightning strike to the object. The protection system includes the gripper system, the drainage system and the grounding system. Lightning strike models are used for the analytical representation of the lightning strike protection system. There are two classic methods, the protective angle method and the empirical curve method. Based on them, an electrogeometric model was developed, which was further developed and applied, in the form of a modified electrogeometric model, in situations that occur in plants in order to arrive at the rolling ball method. This method is based on rolling an imaginary sphere of radius S over the surface of the plant. In the last part of the thesis, a stochastic model for assessing the effectiveness of lightning protection is described. The stochastic assessment of the effectiveness of lightning protection is based on the application of the Monte Carlo method, that is, on the application of a pseudorandom number generator.