Study on Impacts of Distributed Generation Integration in Medium Voltage Radial Distribution system (Case Study: Sebeta-I Substation)
No Thumbnail Available
Date
2018-10
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
AAU
Abstract
The mission of every electric company is to transmit, distribute and supply electricity in reliable
and efficient manner. However in comparison to the part of the power system supplying energy
(the large generating units and the transmission grid), the distribution system, feeding load, is
very extensive and has high R/X ratio causing more power loss, poor voltage stability and large
voltage drop in the network which results with voltage magnitude at the customer terminal out
of permissible limit. On the other hand, increasing power demands has led to the existing aging
power system operation becoming more challenging from the points of security, reliability,
efficiency and quality of the electric power supply.
To catch up with and possibly overtake these issues, integration of distributed generation into
the distribution system is one possible solution. Integrating distributed generation into the
system at a proper place with a proper size makes the grid capable to distribute and supply
electricity in reliable and efficient manner with improvement of several technical parameters.
The purpose of this study is to investigate the impact of distributed generation integration on a
radial distribution system. The feeder SEB-12 of Sebeta-I Substation of medium voltage radial
distribution system which having 44 buses is taken as a case study area to determine the impact
of distributed generation integration on a radial distribution network. The feeder was selected
due to its highest power interruption frequency and long duration power outage during the two
year recorded data. The impacts of DG integration on total power loss, voltage profile, voltage
stability, loading of line segment, fault level, and protection coordination of the distribution
system were investigated.
Modelling of the case study distribution network is simulated using DIgSILENT
PowerFactory 15.1.7 simulation package. The results of base case balanced and positive
sequence load flow analysis at steady state condition indicated that the feeder has total power
loss of 1.91 MW and 2.07 MVAR with the terminal voltage magnitude at the majority of the
buses being out of acceptable limit. The minimum node voltage magnitude of 0.832 p.u.
(12.479 kV) is found at bus 18 which is far out of allowable voltage range of 1±5%. To reduce
the total power loss of the network, and improve voltage profile of the system to within
allowable range, distributed generator is integrated to the network at a proper place with a
proper size. In this thesis sizing and sitting of DG was performed based on analytical method
and load flow analysis respectively. The proper size of DG was found to be 12.098MW with
the proper place at bus 14. The results of simulation after the integration of DG revealed that
the total real and reactive power loss is reduced to 0.30 MW and 0.28 MVAR with the total
loss reduction of 84.29% and 86.47% respectively, while all node voltages had improved to
within permissible limit of 1±5%.
In general, the impact of DG integration on total power loss, voltage profile, loading of line
segment and voltage stability of the system are positive while there are some negative impacts
such as increase in fault level and miss-coordination of protection devices.
Description
Keywords
Distributed generation, DG proper location, DG proper size, Technical parameters, Technical constraints, Loss reduction, DIgSILENT PowerFactory