New concepts on MV distribution from insulated shield wires of HV lines: operation results of an experimental system and applications in Ghana

The authors consider the problem of the most cost-effective power supply to the villages and communities of developing countries located along the route of HV lines which are up to 100 km from HV/MV transformer stations. A novel solution is presented which consists of: insulation of the shield wire(s) of an HV line and wire(s) energization at MV (10 to 34.5 kV) from the closest transformer station: and supply of villages along the line route by means of standard MV/LV distribution transformers connected between the shield wire(s) and ground. Four different schemes are presented, two of them suitable for single-phase distribution, the others for three-phase supply. Results of 33 months of successful operation of an experimental scheme tested in Ghana for supply of single-phase and three-phase loads from the two insulated shield wires of a 161 kV line are presented. The authors describe the distribution schemes along 407 km of new 161 kV lines in northern Ghana, where the novel solution is applied to supply power to both domestic and industrial loads in 12 small towns with a design aggregate load of 5000 kW