ABSTRACT

 This thesis deals with the network reconfiguration for loss reduction in three phase electricity distribution system of the Enugu Electricity Distribution Company (EEDC): A Case Study of the 2X15MVA, 33/11KV Independence-Layout Low Voltage Radial Distribution Network using Exhaustive Search Techniques. The system consist of four feeders viz: New-heaven, Maryland, Presidential and UNEC feeders, feeding sixty seven (67) load distribution substations. The network is characterized with regular power failures, prolonged power outages, high level of power losses : 0.4052MW and 0.6029MVar and low voltage profiles as indicated at the following substations: Nza II 0.6420p.u, Appeal Court 0.8650p.u, Cathedral 0.7720p.u, Nneofia 0.8390p.u, Umuekwumiri 0.8610p.u, INEC 0.7630p.u, NTA 0.8990p.u, EEDC New Store 0.8880p.u, IMT-I 0.8800p.u, IMT-II 0.8710p.u, Nkponkiti-I 0.8650p.u, Nkponkiti-II 0.8620p.u, Ebe Lane-I 0.8560p.u, Ebe Lane-II 0.8540p.u, Ani Street 0.8530p.u, Liberty Estate-II 0.8640p.u, Onyiuke 0.8550p.u, Umuoji 0.8820p.u, Rector Village 0.8990p.u, Bricks-II 0.6410p.u under normal operating conditions which represent voltage violation from the statutory limits of ±5% of base voltage: 0.95 pu/ 1.05 pu. The data for the research work were collected from the EEDC's Independence-Layout Station Enugu from September 2015 to September 2016. Newton-Raphson method of load flow analysis has been employed in studying the system's power flow while bus injection to bus current (BIBC) and branch current to bus voltage (BCBV) matrices alongside a distribution load flow matrix (DLF) are used to solve the reconfiguration problem for optimal solution. The solution converges very early and the execution time is very small. The inputs are given based on the real time data collected from 33/11kV power substation under Enugu Electricity Distribution Company (EEDC). The proposed method has been tested on 70-bus, overhead AC radial distribution network fed by Independence-Layout Station since high level of power dissipation occurs in this system. According to simulation results of load flow analysis, voltage profile enhancement and power loss reduction are revealed in the results. The power loss for the second method "Minimum Voltage Difference Based Reduction" is 0.3222MW and 0.5788MVar. The implementation of the first method: "Minimum Branch Current Based Reduction" produce power loss of 0.3392MW and 0.5909MVar; while the third method: "Voltage Difference Based Closing/Opening" method gave 0.3257MW and 0.5809MVar. The results of the load flow study after simulation of the reconfigured systems showed that "Minimum Voltage Difference Based Reduction" produced the optimal configuration for the 70-bus radial distribution system under study. Power loss reduction in the three reconfigured systems were significant when compared with that of the existing system. From all indications, network reconfiguration is an indispensable method of loss reduction in low voltage radial distribution systems in the foreseen future; especially in developing countries where adequate resources for other methods and manpower are in short supply.