Progress report on the investigations into the recycling of existing HVAC power transmission circuits for higher power transfers using HVDC technology

Cost effective higher current rated power electronic technology makes possible the economic conversion of an existing HVAC transmission circuit for HVDC employment. The objective is to use an existing transmission line and to operate the installed conductors to its full rated current carrying capacity. The paper reports on the boundary conditions for the proposal to upgrade HVAC to HVDC and the technical implications of introducing HVDC onto an existing HVAC tower and line configuration. In conclusion, a possible application of the proposal is presented. Here an existing 3600 MW thermal power station is being prepared for an additional 2100 MW of generation. System planning promotes additional 400 kV or 765 kV HVAC transmission or to upgrade an existing 400 kV line for 500 kV DC application to yield a 3 GW power transfer capability.