Study to Upgrade Existing Hvac Transmission Line to Hvdc : Case of Epp’s Hv Transmission Lines
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Date
2015-05
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Addis Ababa University
Abstract
The increased demand for electrical energy due to increased industrialization and
population growth of Dire Dawa and nearby cities has become a challenge to supply
adequate power using the national grid to Eastern region of Ethiopia. One reason for
these power shortages is the insufficient current carrying capacity of existing high voltage
alternating current, (HVAC), transmission lines supplying the area. High voltage direct
current (HVDC) transmission lines are a possible solution as they provide more power
than HVAC lines.
New parallel HVAC lines, or converting the existing HVAC line to HVDC lines are
possible solutions to improve power delivery in the area. This thesis investigates the
technical feasibility of upgrading existing HVAC lines to HVDC. This option allows the
power transmission rating to be more than doubled and the specific transmission losses to
be substantially reduced without having to widen the right-of-way. What is more, such
conversions cost only a one third the cost of building a new line. Thus main contribution
of this thesis work is the evaluation of a HVDC system including study of technical
compatibility of existing system conversion to HVDC as a solution to overcom power
delivery shortages to Eastern region of Ethiopia.
From the technical performance the bipolar HVDC lines has a loss as much as 69.75%
lower compared to the existing transmission lines and the monopolar HVDC line has a
loss as much as 83.02% lower compared to the existing transmission lines. On the other
hand, the transmission powers of the bipolar HVDC line at ± 500 kV increase by 217%
and the monopolar HVDC line at ± 500 kV increase by 75.8% from the power transfer
capacity of the existing HVAC line. From the cost analysis the cost of conversion is
approximately 36% of cost of new HVAC line. Moreover, conversion of the existing
transmission line to DC line is both financially and economically feasible.
Key Words: HVAC, HVDC,LLC,HVDC control, Transmission line efficiency, corona
loss, investment cost, internal rate of return.
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Keywords
Hvdc, Llc, Hvdc control, Transmission line efficiency, Investment cost, Internal rate of return, Corona loss, Hvac