Improving Voltage Profile and Loss Reduction Of Distribution Substation Using Capacitor Banks Case Study: Kotebe Distribution Substation
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Date
2017-07
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Addis Ababa University
Abstract
Electric transmission and distribution system are the intermediate stages in the transfer
of electrical power from the central generating station to the consumers. Minimization
of power losses and improvement of voltage profile are the most essential concerns of
any electric utility to support increased load requirement. The voltage at buses reduces
due to insufficient amount of reactive power in the network and consequently power
losses increases. There are many numerous activities which have been tried to minimize
distribution loss like upgrading MV and LV distribution conductors, taps changing and
installing new capacitor.
In this thesis work, optimal placements of the capacitors have been suggested. A
methodology to determine the optimal capacitor locations and their sizes to improve
voltage profile and to minimize the line loss of the distribution system has been
developed. The study has been carried out on COTEBE Substation having 42 buses
radial distribution system. The optimal capacitor placement is determined by the
repetitive load flow to achieve the total minimum system loss. DIGSILENT
Powerfactory software is used for Power flow analysis to determine the power loss and
voltage profile of the system. The location of reactive power support allocation has been
studied according to the highest reactive power flow which has been observed. Loss
sensitivity method has been used to determine the optimal capacitor location. The
results of the loss sensitivity are used for the optimal capacitor size selection.
The proposed objective function is the minimization of the total investment cost due to
reactive power support for loss reduction and voltage profile improvement. Different
available capacitors values are used for the test cases, starting from 10KVAr to
10MVAr and the capacitor sizes of 2.2MVAr and 3.3MVAr are selected as an
optimization solution. The selected test case result make that the total grid loss to
decrease from 0.583MW to 0.413MW and the minimum voltage level to increase from
0.905(p.u) to 0.959(p.u). Due to this, the Ethiopian Electric Utility can save 26,132.33$
per annum with the payback period of Fifteen months.
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Keywords
Capacitor Placement, DIGSILENT Powerfactory, Loss Minimization, Voltage Improvement, Cost benefit analysis, Distribution Network in Ethiopia