This paper presents an efficient generator voltage control method for improvement of voltage-reactive states in transmission networks. This method enables fast and sufficiently accurate definition of generator voltages to realize the favorable voltage-reactive states. In peak load state, this generator voltage control is made to improve the economic operation, e.g. to reduce the active and reactive power losses or to enlarge the reactive reserve of generators. In minimum load state, this voltage control is made to reduce the generator under-excitation states, or to make the favorable redistribution of those under-excitation states. The verification of method proposed is made in context of steady-state and dynamic simulation models, on the examples of realized and perspective states of Serbian transmission network, in own wide environment. .