Distribution system expansion planning study with distributed generation (DG)

Abstract

In today's power system, distributed generation is a new solution for meeting electrical demand growth while also meeting operational and technological constraints. Distribution system expansion planning with DG is the best expansion strategies to fulfill the predicted load requirements and to satisfy the operational and technical constraints. The major economical and technical benefits of DG integrated to distribution system are power loss reduction, reduction of complications in expansion planning of distribution network and improving the voltage profile. This thesis focuses on the expansion planning of Nekemte substation with DG. The bus voltage sensitivity analysis method is used for the proper location of DG that to be integrated into the distribution grid network. Peak load demand forecasting is a prerequisite for distribution expansion planning since it predicts demand for the future period. In this thesis, peak load demand forecasting for Nekemte substation distribution system is predicted for the period of 2020 – 2030. The peak load demand forecasting is carried out using least square load demand forecasting techniques. All the compulsory data are collected and distribution system network has been modeled using DigSilent power factory software. To reduce the total power loss of the distribution system network, DG is integrated to distribution system network at proper location with proper capacity. The DG's location and sizing were determined using an analytical approach and load flow analysis. It is shown that the outgoing feeder no-2 and no-3 have the least voltage sensitivity index 0.1379 and 0.1163 respectively and are selected as best location for DG installation. Micro-turbine is chosen as DG from the other DGs in this thesis work based on the availability of the resource and the cost factor. The maximum DG power capacity for feeder no-2 found to be 2.70MW and for feeder no-3 is found to be 3.75MW in MV feeder bus. The result of simulation after integration of DG reveals that active and reactive power loss is reduced to 0.80MW and 2.02MVar with the total loss reduction of 56.76% and 58.18% respectively. Hence, this result shows that even if the load demand increases 8.97% in each year the DG units are able to meet the demand requirements until year-6. After this year the substation should be upgraded to satisfy the load demand