USE OF GENETIC ALGORITHMS FOR ASSESSMENT OF SHIELD EFFECT ON ELECTRIC FIELD PROFILE UNDERNEATH

current transmissions are widely used in power systems because it has many advantages compared with extra high voltage alternating current transmissions. But electric fields emitted from these lines are harmful to a human being living adjacent to these transmissions and required large right of way to protect from these fields. Some studies have reported that children living near extra high voltage direct current transmissions had a higher cancer and leukemia incidence than other children far from these lines.Then reducing electric fields emitted from these lines become very important, and then this thesis introduces a new method to minimize electric fields emitted from these transmission lines by using grounded shield wires underneath extra high voltage direct current transmissions.A charge simulation method was used to calculate electric fields of two types of extra high voltage direct current transmissions (monopolar and bipolar) of 400kV with and without grounded shield wires. A soft computer technique namely genetic algorithm was used also to determine the best location and number of grounded shield wires. The genetic algorithm was applied to a 400kV monopolar dc transmission, it shows that the best location of grounded shield wires is at 15m height above ground level for a number of 5 grounded shield wires at spacing of 6m between them.