The studies undertaken have used the method of Lyapunov of the system theory to evaluate the stability of the electric network starting from the power function depending on the dephasing between voltage and current in time. To carry out these studies, a look into the dynamic stability of the electrical network, and the stability within the meaning of Lyapunov was effected. Then a modelling of our network with application under MATLAB/Simulink was carried out as well as the tests of simulations without disturbances, and another test with disturbances was made. This reveals that the Douala network suffered falls in voltage, increasing instability depending on the critical disturbances, with the network eliminating the faults slowly.