Distribution feeders are components of distribution system which transfer power from distributionrnsubstation to distribution transformers located near to customerâ€™s premises. Distribution substationrnfeeders which have poor power factor, large loads beyond itsâ€™ carrying capacity and which travelrnlong distance to feed costumers are not efficient in transferring electrical power to the connectedrncostumers. To improve the efficiency of distribution feeders in terms of power loss and voltagernprofile, loss minimization and voltage profile improvement techniques are required. rnBella distribution substation is one of the distribution substations found in Addis Ababa Ethiopiarnwhich has six outgoing feeders that feed different areas. Among these feeders, feeder four F4 hasrnbeen selected as test system due to its longest rout length and large loads during a year recordedrndata. The selected feeder has been modeled in MATLAB computational tool and DIgSILENTrnsimulating software and load flow analysis has been simulated using Newton-Raphson methodrnimplemented in MATLAB. rnFrom Newton-Raphson load flow simulation of feeder F4, it has been observed that the feeder hasrna power loss of 3.86MW and voltage drop up to 0.3pu at peak load. To reduce power loss andrnvoltage drop of this feeder, capacitors and distributed generation units have been suggested andrnthe impact is investigated. To find optimal size and location of the capacitors and DG, particlernswarm optimization (PSO) and genetic algorithm (GA) have been implemented in MATLAB.rnPSO based capacitor placement resulted in a placement of capacitor sizes(kVAr) (970, 290, 2690,rn1350, 1110, 120, 370, 1070, 320) on buses of F4(36, 62, 34, 35, 37, 61, 59, 51, 50) respectively.rnPSO based DG placement resulted in a placement of DG sizes (kw) (530.1, 255.6, 241.5, 355.2,rn399.9, 321.9, 176.6, 385) on buses of F4(62, 61, 60, 59, 32, 31, 27, 24) respectively and GA basedrncapacitor placement resulted in a placement of capacitors sizes(kVAr) (1041.8, 540.3, 1599.7,rn1930.6, 1415.2, 26.2, 72, 234.2, 767.2, 858.9) on buses (36, 62, 34, 35, 37, 61, 60, 59, 51, 50)rnrespectively. The initial capital investment cost of PSO based capacitor, PSO based DG and GArnbased capacitor placement on F4 requires 3,317,328 Birr, 184,114,566 Birr and 6,698,160 Birrrnwith respective return of investment 0.1664 year, 6.832 years and 0.3361 year respectively. Peakrnload Newton-Raphson load flow simulation of F4 after separate placement of PSO basedrncapacitor, PSO based DG and GA based capacitor results in power loss and voltage drop reductionrnof (37.3%, 15%), (50%, 12%) and (37.2%, 15.7%) respectively. In addition to peak load, the loadrnflow was simulated at load level of 83% of peak load, 60% of peak load and base load. rnIn general, for power loss reduction and voltage profile improvement of distribution feeders, PSOrnbased capacitor placement is recommended due to the reasonably minimum capital investmentrnand better performance improvement in reduction of power loss and voltage drop.