Assessing the Impact of Distributed Generation in Etekwuru 11/0.415 kV Distribution Sub-Station.

Abstract

In electrical distribution systems, it is crucial to employ methods of power flow optimisation due to the nature of connected loads (inductive), which create voltage dips and power losses. Thus, this research work focusses on evaluating the impact of Distributed Generation (DG) on the overall performance of the system, using the Etekwuru 11/0.415kV distribution network as a case study. To find out what was going on with the power system, a load flow analysis was done. The results showed that 6 of the 11 buses had a critical magnitude of under-voltage, and that the total active and reactive power loss was 42.5 kW and 51.8 kVAr, respectively. Thus, the DG was inserted at Bus 6, and a load flow analysis was carried out to verify its impact on the voltage profile of buses and power losses in the system. The results showed that all of the buses were operating within the IEEE voltage range of +/- 5%. At the same time, the active and reactive power losses dropped significantly, from 42.5 kW to 12.3 kW and from 51.8 kVAr to -9.1 kVAr. Also, a short circuit analysis was done both with and without the DG. The results showed that the DG makes the fault current stronger in the system. The total magnitude of maximum fault current at the buses increased from 52.739 kA to 59.976 kA, while the total magnitude of minimum fault current increased from 38.238 kA to 46.356 kA, respectively. Finally, an over-current protection scheme was created using Siemens 7SJ61 relays along with current transformers and circuit breakers, but not the DG. A three-phase fault was added in several places to see how well the scheme worked, and the results were confirmed by the fact that the relays sent out trip signals when they needed to. It was tested with a three-phase fault after the DG was added to see what effect it had. The results showed that the DG caused the relays to trip too often because it caused a short-circuit creating another research gap for future researchers.