OPTIMAL DISTRIBUTION NETWORK RECONFIGURATION FOR CENTRAL ADDIS-ABABA

Abstract

“Optimal distribution network reconfiguration for Central Addis Ababa” is an engineering issue. The reconfiguration of the distribution network of the city involves classic tools of power systems modeling. The driving criterion in the reconfiguration is minimization of the net present value of the total investment cost of the reconfiguration and the total cost of technical losses of the current distribution system. Loss minimization is essential for an efficient power distribution. Power loss in a distribution network is influenced by factors such as the location of a transformer, loading of a transformer, conductor cross sectional area, length of a conductor, type of a conductor, aging of the network and feeder structure. The cost of investment for reconfiguration of a distribution network mainly focuses on the medium voltage network and installation of sectionalizers. The distribution network in Addis Ababa has a problem of power losses. This power loss in the distribution system occurs due to lack of capacity in substation, distribution line, distribution transformer, improper maintenance, aged equipment that some devices are exceeding their standard lifespan, unbalanced load of distribution transformers, and improper location of distribution transformers, equipment deterioration and improper position of section switches. Therefore, minimizing this power loss by reconfiguration technique is a model case for improving the current power loss situation of the distribution system in Addis Ababa. This thesis proposes distribution power loss minimization using a method of network restructuring. The algorithm used is Feasibility Preserving Simulated Annealing for medium voltage lines. This method is simple and easily understood and is used for complicated radial networks. The result is tested using Windmill software in the Addis Ababa distribution network, which finally optimizes the investment cost for restructuring the distribution network and power loss cost. The major activities in accomplishing the thesis were collecting relevant data from the Addis Ababa distribution network, executing the power loss and power loss cost of the existing network, and reconfiguring the existing network using mathematical analysis, distribution network standards, and software. In this thesis we come up with the result to reduce the power loss of Addis Ababa by 10MVA by means reconfiguration. The base case simulation result indicates that the city encountered a total power loss of 25.94MVA. After reconfiguration, the power loss is reduced to 15.86MVA. Improvement has been recorded in the power flow of the city, xiii which means there is a high reduction in power loss and is expressed in a number of around 61% loss reduction. The cost analysis showed that the amount of money that we lost because of power loss was 81,726,820.00birr annually and the initial investment cost for reconfiguration was 66,810,555.23birr with a return on investment of 0.817 years. Finally, it is recommended distribution networks must have many have many section switches that would be easy for reconfiguration and also it is feasible to invest in the reconfiguration.