Performance Evaluation of Transmission Lines for Power Loss Minimization and Voltage Profile Enhancement Using FACTS Devices (Case Study: 400kV-230kV Transmission Lines in the Ethiopian Power
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Date
2022-01
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Addis Ababa University
Abstract
The transmission system is responsible for transporting the electric power generated at the
generation station to the distribution system. When a power transmission system works with
severely loaded lines, it suffers from power losses and larger voltage deviations, which can cause
the system to malfunction and eventually collapse. Capacitor banks and STATCOM are used in
this thesis in order to reduce line loss and enhance the voltage of the considered system. The
power flow analysis using the Newton-Raphson algorithm in MATLAB software and particle
swarm optimization techniques are utilized to determine the optimal devices sizing and position.
The result shows that, with proper placement of the Capacitor banks and STATCOM on the
identified candidate buses (68, 65, 27, 20) with their optimal sizes, the active power losses of the
system gets improved by 10.78%, 20.57%, 35.84%, 6.602% and 10.76%, 22.29%, 37.79% ,
7.76% in the scenarios of base load, 25% overload, 50% overload and 75% underload
respectively. In scenarios of base load, 25% overload, 50% overload and 75% underload the
voltage magnitudes of weak buses are also improved by 12.5%, 19.41%, 31.15%, 3.23% and
17.5%, 22.8%, 31.4%, 9.84% after the incorporation of Capacitor banks and STATCOM
respectively. The improvements made by the placements of Capacitor banks and STATCOM in
the 75% underload case are not so much significant as the network is almost in a desirable
operating condition under this scenario. Thus, the placement of those FACTS devices for
underload (75% of base load) is not recommended.
The amount of energy cost saved after installing Capacitor bank is 1,825,856.88726 USD,
2,282,320.79712 USD, 2,518,262.57088 USD with Payback periods of 0.516 years, 0.186 years
and 0.0579 years in the scenarios of base load, 25% overload and 50% overload respectively.
And after installing STATCOM, the amount of energy cost saved is 15,339,987.264 USD,
31,399,157.216 USD, 33,744,416.832 USD with Payback periods of 4.344 years, 2.369 years
and 0.485 years in the scenarios of base load, 25% overload and 50% overload respectively.
In general, for power loss minimization and voltage profile enhancements, STATCOM is
proposed for the system due to its better performance during overload as observed from the
simulation results, manages over voltage at under load case and its dynamic capability to inject
reactive power based on the required reactive load.
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Keywords
Transmission line Loss, STATCOM, Capacitor bank, oltage profile, PSO