Abstract:
Power systems in many countries arc stressed towards their stability limit. In Ethiopia,
the number of costumers and specific consumption of electricity is rapidly increasing.
Ethiopian Electric Power Corporation (EEPCO) Interconnected System (ICS) is working
very close to its limit. If these stable systems experience any unexpected serious
contingencies, or disturbances, there is a significant risk of instability, which may lead to
wide-spread blackout. Outage of generating units is one of such disturbances. frequency
is a reliable indicator for such instability conditions that exist on the power system;
therefore under-frequency load shedding technique is used to make the power system
stable by shedding some load in case of generation deficit. ln this thesis, first, the power-
frequency dynamics of EEPCO TCS is studied. Then. two conventional Under Frequency
Load Shedding (UFLS) schemes arc designed analytically and one adaptive scheme is
designed using dynamic simulation. Finally, the proposed load shedding schemes are
tested on the detailed model of EEPCO transmission grid using Power System Simulation
for Engineers (PSS/E) simulation software. The test result showed that all the proposed
schemes improve the existing scheme but the adaptive scheme has better performance.
