Techno economic analysis on the use of fully insulated cable for 33kv overhead power distribution system in Sri Lanka

Abstract

Electricity Supply has become a fundamental commodity of present society. Hence, the availability and the reliability of the electricity distribution system have gained an utmost concern. Currently, Sri Lankan electricity distribution system of all over the island other than Colombo and Kandy Cities are networked through the 33kV Bare Overhead (BOH) lines. Ceylon Electricity Board (CEB) is being rapidly expanded 33 kV distribution network to cater rural electrification demands and the urban development demands. 33kV network has been constructed with poles and towers, many 33 kV lines pass through jungles and thick vegetation and further expose to the sea and lightning prone areas. Therefore, nowadays the utility has to face some critical issues along with existing distribution system, especially higher number of feeder tripping during the rainy seasons due to thick vegetation. Even with the new regulations and demands, lines are unable to maintain right-of-way with required safety clearance especially in urban areas. Thus, in my dissertation discussed the 33kV Aerial Bundled Cable (MVABC) system as a more economical alternative to Medium Voltage Bare Overhead (MVBOH) lines. Further, address how to mitigate certain operational, climatic and environmental issues with MVABC. It is presented a comparative economic analysis of MVABC with MVBOH and MVUG systems. The analysis takes into consideration the initial investment costs, net present value (NPV) of operational and maintenance costs and NPV of unserved energy of lines along with their specific lifetime period. Further, an algorithm has been developed that can be used all over the country to make decision for MVABC adaptation on feeders. Finally, a Software Tool is developed to make easy to generate decision for the same and review each case by doing the Sensitivity Analysis. The dissertation concludes with few recommendations, technical issues associated with MVABC can be mitigated by purchasing cables according to the finalized specification. Use of MVABC shall improve availability and the reliability of consumers’ power supply wherever the decision generated by mathematical model is yes.