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|Title: ||INVESTIGATION OF VSC-HVDC SYSTEM FOR DYNAMIC PERFORMANCE IMPROVEMENT OF EEPCO HIGH VOLTAGE GRID|
|Authors: ||HILAWIE, AHADU|
|Advisors: ||Dr.-Ing. GETACHEW BIRU|
|Keywords: ||Dynamic performance improvement|
bus voltage profiles
|Copyright: ||Jun-2011 |
|Date Added: ||3-May-2012 |
|Abstract: ||The Ethiopian Electric Power Corporation (EEPCO) is, currently, undertaking a huge electric
power generation expansion. The generation capacity under construction is about 7757 MW.
This huge expansion demands existing AC transmission line upgrading and new transmission
line installations. On the other hand, instability problems have occurred frequently within
EEPCo system manifesting themselves in the form of system blackouts.
Considering these two problems this thesis work proposes integration of Voltage Source
Converter Based High Voltage Direct Current (VSC-HVDC) transmission system for
improving future system stability and enhancing power transfer capability.
The thesis investigates the dynamic performance improvements that can be attained through
integrating VSC-HVDC transmission system. The investigation started by developing a
monopolar VSC-HVDC transmission model with a complete control system on Digital
Simulation and Electrical Network calculation program (DIgSILENT power factory) software.
Different controllers are designed including, faster inner current controllers having transient
response specifications: rise time 0.0003 s, settling time 0.000842 s; DC voltage controller
having transient response specifications: rise time 0.00156 s, settling time 0.0132 s; and outer
PQ controllers. Then the performance of the control system is evaluated and found to function
satisfactorily at supporting bidirectional power flow and at maintaining stability during
disturbances. Finally the designed VSC-HVDC link is integrated to North-Western EEPCo
high voltage grid model and time domain simulations are carried out to investigate system
dynamic performance improvement. It is obtained that with the proposed option the system
pre-disturbance bus voltage values are improved from below 0.95 pu to 1 pu and post
disturbance bus voltage values are improved from below 0.9 pu to above 0.95 pu. On the other
hand system low load higher voltage values that go beyond upper limit of 1.05 are managed to
come within the limit. A better damping of generators’ rotor angle oscillations is also attained
showing general system dynamic performance improvement.|
|Appears in:||Thesis - Electrical Engineering|
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