Evaluation of Static Voltage Stability of Ethiopian Grid

A power system is set to operate within its maximum operating limits for better utilization of the existing network facilities. The main factor causing voltage instability is the inability of a power system to meet the demand for reactive power. A system enters a state of voltage instability due to loss of loaded generation unit or transmission line, or a change in loading conditions that causes progressive and uncontrollable decline or rise in voltage. This thesis attempts to evaluate voltage stability problems of Ethiopian high voltage transmission grid. Load flow simulations using PSS/E software has been done for peak load (2,200 MW) and light-load (900 MW) conditions. After conducting load flow simulations, ¿Voltage limit checking¿ results within tolerable range of +/- 0.05 pu is applied to identify the buses/areas with unacceptable low and high voltage values. Low voltage profiles during peak hour are registered around Addis Ababa, and high voltage values are registered at North-western part of Ethiopia, i.e. around Bahirdar & Debre Markos.