Abstract:
n 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.
