Modeling of a Resistant Earth Protection Relay and Comparison of the Neutral Regimes on the HV / MV Transformers

The main challenge in the electricity networks VHV, HV or MV is to satisfy the customer and this by two important factors: the quality and continuity of service, that is why we must ensure the stability of the electricity network, this is the important role played by the protection systems participating to this goal, faced to a various faults affecting the electrical networks sometimes caused by thunderstorms, lightning, short circuits caused by other external objects, as well as earth faults ... In most cases, electrical faults are manifested by mechanical damage, costing a lot of money. To this end we have chosen the neutral protection EHV (Electrical High Voltage), this system is of great importance among others, to preserve the factors raised. In this paper we have evaluated the nature of the faults in direct connection or not to the ground and better understand them by creating a simulation of a protection relay on Simulink MATLAB allowing the best possible to recreate the real phenomenon either the defect or the behavior of system of protection.