In this book an electric power system is considered, we design mathematical model for the determination of the increase in operational cost of transmission line caused by reactive power transmission, and decrease the Losses in electric power system by derived mathematical relations to determine an economically justified transmission distance for VARs transmission. Also, detailed analyses to help determine the increase in production costs due to the transmission of reactive power are given. The main purpose of the book is to introduce the detailed analyses of artificial neural networks which help to choosing suitable network based on a prior knowledge of the process and determine the suitable training algorithm to solve the reactive power and voltage control problems to increase the electric network effectiveness, it allows to reduce the electric power losses, substation loading and to improve the electric power quality. Then describes the implementation of this network for active and reactive power transfer allocation. Finally, we applied these modeling and network designer on the substations in west of Iraq country.